U.S. patent application number 14/012072 was filed with the patent office on 2014-07-03 for power system for dosimeter reader.
This patent application is currently assigned to Landauer, Inc.. The applicant listed for this patent is Landauer, Inc.. Invention is credited to Mark S. AKSELROD, Kent J. DILLIN, Vasiliy V. FOMENKO, David F. JOHNSON, Tse-Min LO, Yoshikazu TATSUMI, R. Craig YODER.
Application Number | 20140183378 14/012072 |
Document ID | / |
Family ID | 44763340 |
Filed Date | 2014-07-03 |
United States Patent
Application |
20140183378 |
Kind Code |
A1 |
YODER; R. Craig ; et
al. |
July 3, 2014 |
POWER SYSTEM FOR DOSIMETER READER
Abstract
Described is a portable dosimeter reader that is small in size
and light in weight.
Inventors: |
YODER; R. Craig; (Crown
Point, IN) ; AKSELROD; Mark S.; (Stillwater, OK)
; DILLIN; Kent J.; (Stillwater, OK) ; FOMENKO;
Vasiliy V.; (Stillwater, OK) ; JOHNSON; David F.;
(Placitas, NM) ; TATSUMI; Yoshikazu; (Chicago,
IL) ; LO; Tse-Min; (Glenwood, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Landauer, Inc. |
Glenwood |
IL |
US |
|
|
Assignee: |
Landauer, Inc.
Glenwood
IL
|
Family ID: |
44763340 |
Appl. No.: |
14/012072 |
Filed: |
August 28, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13082494 |
Apr 8, 2011 |
8552403 |
|
|
14012072 |
|
|
|
|
61322418 |
Apr 9, 2010 |
|
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|
Current U.S.
Class: |
250/458.1 ;
250/216; 250/484.5 |
Current CPC
Class: |
G01T 1/10 20130101; G01T
1/115 20130101; G01T 1/105 20130101 |
Class at
Publication: |
250/458.1 ;
250/484.5; 250/216 |
International
Class: |
G01T 1/105 20060101
G01T001/105; G01T 1/10 20060101 G01T001/10 |
Claims
1. (canceled)
2. The device of claim 8, further comprising the one or more
batteries.
3. The device of claim 2, wherein the one or more batteries
comprise four AA batteries.
4. The device of claim 2, wherein the total weight of the one or
more batteries is less than about 100 g.
5. The device of claim 2, wherein the total weight of device
including the one or more batteries is about 2,700 g or less.
6. The device of claim 8, wherein the one or more batteries
comprise four AA batteries.
7. The device of claim 8, wherein the total weight of the device
excluding the one or more batteries is 2,600 g or less.
8. A device comprising: an optically stimulated luminescence (OSL)
reader for reading one or more OSL sensors of a dosimeter sled; a
sled slider that is driven by an engine to position in turn each of
the one or more OSL sensors of the dosimeter sled at a reading
position where the OSL reader reads each respective OSL sensor; a
display for displaying information relating to reading the one or
more OSL sensors; and a battery compartment for retaining one or
more batteries, wherein the OSL reader includes an LED light
source, wherein the battery compartment is electrically connected
to the OSL reader, the engine and the display, and wherein the one
or more batteries provide all of the power required for operating
the OSL reader, the engine and the display, wherein each of the one
or more OSL sensors comprises: an optically stimulated luminescent
material (OSLM) mounted in one or more cylindrical cup-shaped
energy compensating filters; one or more discs of filter material
sandwiched between a filtered side of the OSLM and a selected
cylindrical cup-shaped energy compensating filter of the one or
more cylindrical cup-shaped energy compensating filters.
9. The device of claim 8, wherein the OSLM comprises an
Al.sub.2O.sub.3:C material.
10. The device of claim 8, wherein the device requires a current of
90 mA for less than 1 second to read each of the one or more OSL
sensors.
11. The device of claim 8, wherein the device requires a current of
80 mA or less when in a powered idle state prior to reading the one
or more OSL sensors.
12. The device of claim 8, wherein the device is mounted in a
clamshell case.
13. The device of claim 8, wherein the device includes a handle for
carrying the device in one hand.
14. A device comprising: an optically stimulated luminescence (OSL)
reader for reading one or more OSL sensors of a dosimeter sled; a
sled slider that is driven by an engine to position in turn each of
the one or more OSL sensors of the dosimeter sled at a reading
position where the OSL reader reads each respective OSL sensor; a
display for displaying information relating to reading the one or
more OSL sensors; a battery compartment for one or more batteries;
and a case enclosing the device, wherein when the case is in a
closed configuration, the device has a total volume of about 3,065
cm.sup.3 or less, wherein each of the one or more OSL sensors
comprises: an optically stimulated luminescent material (OSLM)
mounted in one or more cylindrical cup-shaped energy compensating
filters; one or more discs of filter material sandwiched between a
filtered side of the OSLM and a selected cylindrical cup-shaped
energy compensating filter of the one or more cylindrical
cup-shaped energy compensating filters.
15. The device of claim 14, wherein the device includes a handle
for carrying the device in one hand.
16.-38. (canceled)
39. A device comprising: a radiation dosimeter including one or
more optically stimulated luminescence (OSL) sensors; and a strap
member for wrapping around a portion of a body or a portion of an
article of clothing to thereby allow the dosimeter to be worn by an
individual, wherein the dosimeter includes an upper housing and a
lower housing, wherein the upper housing is separable from the
lower housing, wherein the one or more of the OSL sensors each
comprise an optically stimulated luminescent material (OSLM) and
one or more filters, wherein the upper housing includes interior
screw threads that engage exterior screw threads on the lower
housing, and wherein is separable from the lower housing when the
upper housing is turned 90.degree. relative to the lower housing
from a position in which the lower housing is mounted in the upper
housing. wherein the dosimeter includes two loops on opposite sides
of the dosimeter through which the strap member is threaded and
which are graspable by an individual to thereby allow the
individual to turn the upper housing 90.degree. relative to the
lower housing when the lower housing is prevented from rotating,
wherein the lower housing comprises one or more rotation preventing
engagement structures for engaging respective one or more
complementary rotation preventing engagement structures of a
dosimeter reader to prevent rotation of the lower housing when the
lower housing is loaded in the dosimeter reader, and wherein the
lower housing comprises one or more retaining structures for
engaging respective one or more complementary retaining structures
of the dosimeter reader to retain the lower housing that is loaded
in the dosimeter reader from lifting up from the dosimeter reader
when the upper housing of the dosimeter reader is lifted up from
the lower housing.
40. A device comprising: a radiation dosimeter comprising: a
dosimeter sled including one or more optically stimulated
luminescence (OSL) sensors; an upper housing; and a lower housing;
and a clip for attachment to a portion of an article of clothing to
thereby allow the dosimeter to be worn by an individual, wherein
the one or more of the OSL sensors each comprise an optically
stimulated luminescent material (OSLM) and one or more filters,
wherein the upper housing includes interior screw threads that
engage exterior screw threads on the lower housing, wherein the
upper housing is separable from the lower housing when the upper
housing is turned 90.degree. relative to the lower housing from a
position in which the lower housing is mounted in the upper
housing, wherein the dosimeter sled is slidably mounted in the
lower housing, wherein the lower housing comprises one or more
rotation preventing engagement structures for engaging respective
one or more complementary rotation preventing engagement structures
of a dosimeter reader to prevent rotation of the lower housing when
the lower housing is loaded in the dosimeter reader, and wherein
the lower housing comprises one or more retaining structures for
engaging respective one or more complementary retaining structures
of the dosimeter reader to retain the lower housing that is loaded
in the dosimeter reader from lifting up from the dosimeter reader
when the upper housing of the dosimeter reader is lifted up from
the lower housing, wherein the dosimeter includes two loops on
opposite sides of the dosimeter which are graspable by an
individual to thereby allow the individual to turn the upper
housing 90.degree. relative to the lower housing when the lower
housing is prevented from rotating and wherein the clip is attached
to one of the two loops.
41. A device comprising: a radiation dosimeter including one or
more optically stimulated luminescence (OSL) sensors; and a clip
for attachment to a portion of an article of clothing to thereby
allow the dosimeter to be worn by an individual, wherein the one or
more of the OSL sensors each comprise an optically stimulated
luminescent material (OSLM) and one or more filters, wherein the
dosimeter includes an upper housing and a lower housing and wherein
the upper housing is separable from the lower housing, wherein the
upper housing includes interior screw threads that engage exterior
screw threads on the lower housing, and wherein the upper housing
is separable from the lower housing when the upper housing is
turned 90.degree. relative to the lower housing from a position in
which the lower housing is mounted in the upper housing, wherein
the dosimeter includes two loops on opposite sides of the dosimeter
which are graspable by an individual to thereby allow the
individual to turn the upper housing 90.degree. relative to the
lower housing when the lower housing is prevented from rotating and
wherein the clip is attached to one of the two loops, wherein the
lower housing comprises one or more rotation preventing engagement
structures for engaging respective one or more complementary
rotation preventing engagement structures of a dosimeter reader to
prevent rotation of the lower housing when the lower housing is
loaded in the dosimeter reader, and wherein the lower housing
comprises one or more retaining structures for engaging respective
one or more complementary retaining structures of the dosimeter
reader to retain the lower housing that is loaded in the dosimeter
reader from lifting up from the dosimeter reader when the upper
housing of the dosimeter reader is lifted up from the lower
housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority to U.S.
Provisional Patent Application No. 61/322,418 to Yoder, entitled
POWER SYSTEM FOR DOSIMETER READER, filed Apr. 9, 2010, which is
incorporated herein by reference in its entirety. This application
also makes reference to the following U.S. and PCT Patent
Applications: U.S. patent application Ser. No. 12/757,147 filed
Apr. 9, 2010 and PCT Patent Application No: PCT/IB2011/050090,
filed Jan. 10, 2011, entitled PORTABLE DOSIMETER; U.S. patent
application Ser. No. 12/757,132 filed Apr. 9, 2010 and PCT
Application No: PCT/IB2011/050092, filed Jan. 10, 2011, entitled
NOVEL FILTERS FOR USE IN DOSIMETRY; U.S. patent application Ser.
No. 12/757,162 filed Apr. 9, 2010 and PCT Patent Application No:
PCT/IB2011/050093, filed Jan. 10, 2011, entitled DOSIMETER SLED;
U.S. patent application Ser. No. 12/757,140 filed Apr. 9, 2010,
entitled PORTABLE READER FOR A DOSIMETER; U.S. patent application
Ser. No. 12/757,168 filed Apr. 9, 2010 and PCT Patent Application
No: PCT/IB2011/050094, filed Jan. 10, 2011, entitled DATA STORAGE
MECHANISM AND COMMUNICATION MECHANISM FOR PORTABLE DOSIMETER; U.S.
patent application Ser. No. 12/757,194 filed Apr. 9, 2010 and PCT
Patent Application No. PCT/IB2011/050088 filed Jan. 10, 2011,
entitled READING MECHANISM FOR DOSIMETER; U.S. patent application
Ser. No. 12/757,214 filed Apr. 9, 2010 and PCT Patent Application
No: PCT/IB2011/050097 filed Jan. 10, 2011, entitled OPTICAL SYSTEM
FOR DOSIMETER WITH READER; U.S. patent application Ser. No.
12/757,184 filed Apr. 9, 2010 and PCT Patent Application No:
PCT/IB2011/050098 filed Jan. 10, 2011, entitled DOSIMETER WITH RFID
TAG; and U.S. patent application Ser. No. 12/757,224 filed Apr. 9,
2010, entitled NOVEL RFID TAG FOR USE IN DOSIMETRY.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a portable dosimeter
reader.
[0004] 2. Related Art
[0005] Many existing dosimeter readers are relatively large and
heavy and, therefore, are not portable. Many existing dosimeter
readers are also not capable of being run solely by battery
power.
SUMMARY
[0006] According to a first broad aspect, the present invention
provides a device comprising: an optically stimulated luminescence
(OSL) reader for reading one or more OSL sensors of a dosimeter
sled; a sled slider that is driven by an engine to position in turn
each of the one or more OSL sensors of the dosimeter sled at a
reading position where the OSL reader reads each respective OSL
sensor; a display for displaying information relating to reading
the one or more OSL sensors; and a battery compartment for one or
more batteries, wherein the OSL reader includes an LED light
source, wherein the battery compartment is electrically connected
to the OSL reader, the engine and the display, and wherein the one
or more batteries provide all of the power required for operating
the OSL reader, the engine and the display.
[0007] According to a second broad aspect, the present invention
provides a device comprising: an optically stimulated luminescence
(OSL) reader for reading one or more OSL sensors of a dosimeter
sled; a sled slider that is driven by an engine to position in turn
each of the one or more OSL sensors of the dosimeter sled at a
reading position where the OSL reader reads each respective OSL
sensor; a display for displaying information relating to reading
the one or more OSL sensors; a battery compartment for one or more
batteries; and a case enclosing the device, wherein when the case
is in a closed configuration, the device has a total volume of
about 3,065 cm.sup.3 or less.
[0008] According to a third broad aspect, the present invention
provides a device comprising: an optically stimulated luminescence
(OSL) reader for reading one or more OSL sensors of a dosimeter; a
dosimeter drawer slidably mounted in the device, the dosimeter
drawer comprising: a drawer base include two tab openings through
which two retaining tabs extend; and a drawer handle for pushing
and pulling the dosimeter drawer so that that drawer slides in a
first direction and a second direction that are opposite to each
other; first and second loop retainers extending through respective
post openings in the drawer base, wherein the drawer base includes
one or more first engagement structures for engaging one or more
second engagement structures on a lower housing of the dosimeter
when the dosimeter is loaded in the dosimeter drawer whereby the
lower housing is prevented from rotating relative to the drawer
base; wherein the sliding of the dosimeter drawer in the first
direction causes the two retaining tabs engage respective lips and
cutouts of recesses on the lower housing of the dosimeter to retain
the lower housing of the dosimeter on the drawer base when an upper
housing of the dosimeter is separated from the lower housing of the
dosimeter, wherein the first and second loop retaining posts retain
respective first and second loops of the upper housing of the
dosimeter when the upper housing of the dosimeter is rotated
approximately 90.degree. relative to the lower housing to release
the upper housing from the lower housing, wherein the first and
second loop retainers raise the upper housing above the lower
housing when the upper housing is retained by the first and second
loop retaining posts and when the dosimeter drawer is pushed in the
first direction, and wherein the first and second loop retainers
lower the upper housing separated from the lower housing on the
lower housing when the dosimeter drawer is pulled in the second
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings, which are incorporated herein and
constitute part of this specification, illustrate exemplary
embodiments of the invention, and, together with the general
description given above and the detailed description given below,
serve to explain the features of the invention.
[0010] FIG. 1 is an image of the bottom of a radiation dosimeter
according to one embodiment of the present invention;
[0011] FIG. 2 is an image of the top of the radiation dosimeter of
FIG. 1 and of the top of the upper housing of the radiation
dosimeter of FIG. 1;
[0012] FIG. 3 is an image of the bottom of the upper housing of
FIG. 2;
[0013] FIG. 4 is an image of the top of the lower housing of the
radiation dosimeter of FIG. 1;
[0014] FIG. 5 is an image of the bottom of the lower housing of
FIG. 4;
[0015] FIG. 6 is an image of the top of the sled of the radiation
dosimeter of FIG. 1;
[0016] FIG. 7 is an image of the bottom of the sled of FIG. 6;
[0017] FIG. 8 is an image of the reference OSL sensor the sled of
FIG. 6 showing the reference OSL sensor in a disassembled
state;
[0018] FIG. 9 is an image of the reference OSL sensor of FIG. 6 in
an assembled state;
[0019] FIG. 10 is an image of the sled of FIG. 6 being slid into
the lower housing of FIG. 4;
[0020] FIG. 11 is an image of the dosimeter sled of FIG. 6 fully
slid into the lower housing of FIG. 4;
[0021] FIG. 12 is a top perspective view of an upper housing of a
radiation dosimeter according to one embodiment of the present
invention;
[0022] FIG. 13 is a bottom perspective view of the upper housing of
FIG. 12;
[0023] FIG. 14 is a top plan view of the upper housing of FIG.
12;
[0024] FIG. 15 is a bottom plan view of the upper housing of FIG.
12;
[0025] FIG. 16 is a cross-sectional view of the upper housing of
FIG. 12 taken along line A-A of FIG. 14;
[0026] FIG. 17 is a top perspective view of a lower housing of a
radiation dosimeter according to one embodiment of the present
invention;
[0027] FIG. 18 is a bottom perspective view of the lower housing of
FIG. 17;
[0028] FIG. 19 is a top plan view of the lower housing of FIG.
17;
[0029] FIG. 20 is a bottom plan view of the lower housing of FIG.
17;
[0030] FIG. 21 is a cross-sectional view of the lower housing of
FIG. 17 taken along line B-B of FIG. 19;
[0031] FIG. 22 is a cross-sectional view of the lower housing of
FIG. 17 taken along line C-C of FIG. 20;
[0032] FIG. 23 is a cross-sectional view of the lower housing of
FIG. 17 taken along line D-D of FIG. 21;
[0033] FIG. 24 is a cross-sectional view of the lower housing of
FIG. 17 taken along line E-E of FIG. 22;
[0034] FIG. 25 is a top perspective view of a dosimeter sled body
of a dosimeter according to one embodiment of the present
invention;
[0035] FIG. 26 is a bottom perspective view of the dosimeter sled
body of FIG. 25;
[0036] FIG. 27 is a top plan view of the dosimeter sled body of
FIG. 25;
[0037] FIG. 28 is a bottom plan view of the dosimeter sled body of
FIG. 25;
[0038] FIG. 29 is a side view of the dosimeter sled body of FIG.
25;
[0039] FIG. 30 is a cross-sectional view of the dosimeter sled body
of FIG. 25 taken along line E-E of FIG. 27;
[0040] FIG. 31 is an end view of the dosimeter sled body of FIG.
25;
[0041] FIG. 32 is an end view of the dosimeter sled body of FIG. 25
of the opposite end of the dosimeter sled from the end shown in
FIG. 31;
[0042] FIG. 33 is a cross-sectional view of the dosimeter sled body
of FIG. 25 taken along line F-F of FIG. 28;
[0043] FIG. 34 is bottom plan view of a dosimeter sled according to
one embodiment of the present invention;
[0044] FIG. 35 is a cross-sectional view of the dosimeter sled of
FIG. 34 taken along line G-G of FIG. 34.
[0045] FIG. 36 is a top perspective view of an upper housing of a
radiation dosimeter according to one embodiment of the present
invention;
[0046] FIG. 37 is a top perspective view of an upper housing of a
radiation dosimeter according to one embodiment of the present
invention;
[0047] FIG. 38 is an exploded view of a radiation dosimeter
according to one embodiment of the present invention;
[0048] FIG. 39 is a bottom plan view of the dosimeter sled body of
the radiation dosimeter of FIG. 38;
[0049] FIG. 40 is an image of the dosimeter sled of the radiation
dosimeter of FIG. 38;
[0050] FIG. 41 is a top perspective view of an upper housing of a
radiation dosimeter according to one embodiment of the present
invention;
[0051] FIG. 42 is a bottom perspective view of the upper housing of
FIG. 41;
[0052] FIG. 43 is a top plan view of the upper housing of FIG.
41;
[0053] FIG. 44 is a bottom plan view of the upper housing of FIG.
41;
[0054] FIG. 45 is a cross-sectional view taken along line H-H of
FIG. 43;
[0055] FIG. 46 is a top perspective view of a dosimeter sled body
of a dosimeter according to one embodiment of the present
invention;
[0056] FIG. 47 is a bottom perspective view of the dosimeter sled
body of FIG. 46;
[0057] FIG. 48 is a top plan view of the dosimeter sled body of
FIG. 46;
[0058] FIG. 49 is a bottom plan view of the dosimeter sled body of
FIG. 46;
[0059] FIG. 50 is a side view of the dosimeter sled body of FIG.
46;
[0060] FIG. 51 is a cross-sectional view of the dosimeter sled body
of FIG. 46 taken along line I-I of FIG. 48;
[0061] FIG. 52 is an end view of the dosimeter sled body of FIG.
46;
[0062] FIG. 53 is an end view of the dosimeter sled body of FIG. 46
of the opposite end of the dosimeter sled from the end shown in
FIG. 51;
[0063] FIG. 54 is a cross-sectional view of the dosimeter sled body
of FIG. 46 taken along line J-J of FIG. 49;
[0064] FIG. 55 is a close-up perspective view of the FNTD holder of
the dosimeter sled body of FIG. 46;
[0065] FIG. 56 is a cross-sectional view of a lower housing of a
dosimeter, the upper housing of FIG. 41 and the dosimeter sled body
of FIG. 46 assembled together;
[0066] FIG. 57 is a cross-sectional view of a sealing engagement
between the lower housing and upper housing of FIG. 56;
[0067] FIG. 58 is a top plan view of an OSL sensor according to one
embodiment of the present invention;
[0068] FIG. 59 is a cross-sectional view of the OSL sensor of FIG.
58 taken along line K-K:
[0069] FIG. 60 is a top plan view of an inner filter in which is
mounted an OSLM of the OSL sensor of FIG. 58;
[0070] FIG. 61 is a cross-sectional view of an inner filter and
OSLM of FIG. 60 taken along line L-L of FIG. 60:
[0071] FIG. 62 is a top plan view of a retaining ring of the OSL
sensor of FIG. 58 with the retaining ring shown in a relaxed
state;
[0072] FIG. 63 is a cross-sectional view of the retaining ring of
FIG. 58 taken along line M-M of FIG. 62:
[0073] FIG. 64 is a top plan view of a cylindrical cup-shaped outer
filter of the OSL sensor of FIG. 58;
[0074] FIG. 65 is a cross-sectional view of the outer filter of
FIG. 61 taken along line N-N of FIG. 64:
[0075] FIG. 66 is an image of a radiation dosimeter of the present
invention with a wristband according to one embodiment of the
present invention with the wristband threaded below the lower
housing of the radiation dosimeter;
[0076] FIG. 67 is an image of a radiation dosimeter of the present
invention with a wristband according to one embodiment of the
present invention with the wristband threaded above the upper
housing of the radiation dosimeter;
[0077] FIG. 68 is an image of a radiation dosimeter of the present
invention with a clip according to one embodiment of the present
invention;
[0078] FIG. 69 is an image of a dosimeter reader according to one
embodiment of the present invention;
[0079] FIG. 70 is a close-up image of a dosimeter reader body of
the dosimeter reader of FIG. 69;
[0080] FIG. 71 is an image of a dosimeter reader case and the
dosimeter reader body of the dosimeter reader of FIG. 69;
[0081] FIG. 72 is an image of a dosimeter drawer of the dosimeter
reader of FIG. 69;
[0082] FIG. 73 is a close-up image of one of two loop retainers
extending through a drawer base of the dosimeter drawer of FIG.
72;
[0083] FIG. 74 is a close-up image of the other loop retainer
extending through a drawer base of the dosimeter drawer of FIG.
72;
[0084] FIG. 75 shows two spring tabs extending through openings in
the drawer base of the dosimeter drawer of FIG. 72;
[0085] FIG. 76 is an image of the dosimeter reader of FIG. 69 with
a housing cover removed to provide a close-up image of the RFID tag
reader of the dosimeter reader of FIG. 69;
[0086] FIG. 77 image of the dosimeter reader body of the dosimeter
reader of FIG. 69 with the housing cover removed to show details of
a ready region housing, a reader housing and an OSL reader of the
dosimeter reader of FIG. 69;
[0087] FIG. 78 is an image showing a sled slider of the OSL reader
of FIG. 77;
[0088] FIG. 79 is an image showing a sled slider motor of the OSL
reader of FIG. 77 and a wall of the reader housing;
[0089] FIG. 80 is an image of the OSL reader of FIG. 77 with the
slider positioned so that the optical light pipe of the OSL reader
may be seen;
[0090] FIG. 81 is a close-up image of the optical light-pipe of
FIG. 80;
[0091] FIG. 82 is a schematic drawing that shows how a dosimeter
sled blocks the light path of a photo-optic sensor according to one
embodiment of the present invention when the dosimeter sled is not
in a reading position for an OSL sensor;
[0092] FIG. 83 is a schematic drawing that shows how a notch in the
dosimeter sled opens the light path of the photo-optic sensor of
FIG. 82 when the dosimeter sled in a reading position for an OSL
sensor;
[0093] FIG. 84 is an image of the underside of the dosimeter reader
body of the dosimeter reader of FIG. 69;
[0094] FIG. 85 is an image of the underside of the OSL reader of
FIG. 77;
[0095] FIG. 86 is an image of the loop retainer elevator of an
elevator carriage of the dosimeter reader body of FIG. 84 in a
fully lowered position;
[0096] FIG. 87 is an image of the loop retainer elevator of FIG. 87
in an intermediate raised position;
[0097] FIG. 88 is an image of the loop retainer elevator of FIG. 87
in a fully raised position;
[0098] FIG. 89 is an image of the elevator carriage of the
dosimeter reader body of FIG. 84;
[0099] FIG. 90 is an image showing a pinion gear of the elevator
carriage and two retaining tabs slidably mounted in curved slots in
the pinion gear;
[0100] FIG. 91 is a close up image of the pinion gear and retaining
tabs of FIG. 89;
[0101] FIG. 92 is an image of the photo-optical engine frame of the
dosimeter reader of FIG. 69;
[0102] FIG. 93 is an image of the photo-optical engine frame of
FIG. 92 from a different angle;
[0103] FIG. 94 is an exploded view of a photo-optical engine of the
OSL reader of the dosimeter reader of FIG. 69;
[0104] FIG. 95 is a partially exploded view of the photo-optical
engine of FIG. 94 with the filter optical assembly shown in
simplified form in an assembled state and the sides of the body of
the photo-optical engine made transparent to better show interior
detail;
[0105] FIG. 96 is a perspective view of the photo-optical engine of
FIG. 94 in a partially assembled state with various features of the
photo-optical engine made transparent to better show interior
detail;
[0106] FIG. 97 is a side view of the partially assembled
photo-optical engine of FIG. 96 with various features of the
photo-optical engine made transparent to better show interior
detail;
[0107] FIG. 98 is a perspective view of an LED interconnect PCB
assembly of the photo-optical engine of FIG. 94;
[0108] FIG. 99 is an exploded view of the LED interconnect PCB
assembly of FIG. 98 with the PCB of the LED interconnect PCB
assembly shown in a simplified form;
[0109] FIG. 100 is a side view of the photo-optical engine of FIG.
94 in an assembled state with part of the photo-optical engine
broken away to show interior details;
[0110] FIG. 101 is a cross-sectional view of the circled region of
the photo-optical engine in FIG. 99.
[0111] FIG. 102 is a schematic diagram of the OSL reader and RFID
tag reader of the dosimeter reader of FIG. 69;
[0112] FIG. 103 is an image of a radiation dosimeter of the present
invention loaded in the dosimeter drawer of the dosimeter reader of
FIG. 69 with the radiation dosimeter in a starting position;
[0113] FIG. 104 is a close-up image of the radiation dosimeter and
dosimeter drawer of FIG. 103;
[0114] FIG. 105 is an image showing the radiation dosimeter of FIG.
103 rotated to a rotated position where the upper housing of the
radiation dosimeter is released from the lower housing of the
radiation dosimeter;
[0115] FIG. 106 is a cross-sectional view of a portion of the lower
housing of the radiation dosimeter of FIG. 103 and the two spring
tabs of the dosimeter reader of FIG. 69 showing how the two spring
tabs of the dosimeter reader retain the lower housing of the
radiation dosimeter on the drawer base of the dosimeter drawer of
FIG. 103 as dosimeter drawer and radiation dosimeter are pushed
towards a dosimeter ready region of the dosimeter reader;
[0116] FIGS. 107, 108 and 109 are images showing the radiation
dosimeter and dosimeter drawer of FIG. 103 being pushed into the
ready region housing of the dosimeter reader of FIG. 69 and the
upper housing of the radiation dosimeter being raised above the
lower housing of the radiation dosimeter;
[0117] FIG. 110 is an image showing the radiation dosimeter and
dosimeter drawer of FIGS. 106, 107 and 108 fully pushed into the
ready region housing;
[0118] FIG. 111 shows the dosimeter reader in the state shown in
FIG. 110 in which the housing cover is removed to show interior
details including the radiation dosimeter in the ready region
housing;
[0119] FIG. 112 shows the radiation dosimeter reader in the state
shown in FIG. 111 with the upper housing removed to show the slider
of the OSL reader engaging the dosimeter sled of the radiation
dosimeter;
[0120] FIG. 113 shows the dosimeter sled of FIG. 112 being pulled
out of the lower housing of the radiation dosimeter and being
pulled into the OSL reader housing by the puller pusher of the OSL
reader;
[0121] FIG. 114 shows the dosimeter sled of FIG. 113 pulled by the
slider of the OSL reader to a reading position for the comparator
OSL filter of the dosimeter sled;
[0122] FIG. 115 shows the dosimeter sled of FIG. 114 pulled by the
slider of the OSL reader to a reading position for the reference
OSL filter of the dosimeter sled;
[0123] FIG. 116 is a graph of a photon energy response of Al, CuT
and CuP filters;
[0124] FIG. 117 is a graph of a photon energy response of Al, CuT
and CuP filters relative to Cs-137; and
[0125] FIG. 118 is a graph of a photon energy response of Al and
CuP filters relative to CuT.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Definitions
[0126] Where the definition of terms departs from the commonly used
meaning of the term, applicant intends to utilize the definitions
provided below, unless specifically indicated.
[0127] For the purposes of the present invention, directional terms
such as "top", "bottom", "upper", "lower", "above", "below",
"left", "right", "horizontal", "vertical", "upward", "downward",
etc., are merely used for convenience in describing the various
embodiments of the present invention.
[0128] For the purposes of the present invention, a value or
property is "based" on a particular value, property, the
satisfaction of a condition, or other factor, if that value is
derived by performing a mathematical calculation or logical
decision using that value, property or other factor.
[0129] For the purposes of the present invention, the term "angle
of incidence" refers to the angle between the direction of the
radiation trajectory and a line perpendicular (normal) to the
detector surface.
[0130] For the purposes of the present invention, the term "close
proximity" refers to a distance comparable with the penetration
range of charged particles in a particular medium.
[0131] For the purposes of the present invention, the term
"comparator OSL sensor" refers an OSL sensor that includes a
reference filter material and is used to adjust the dose determined
by the reference sensor at very low energies of x-rays or gamma
rays. In some embodiments of the present invention, the reference
filter material of a comparator OSL sensor may be applied as a thin
coating on an OSLM or be mounted as a thin film or disc adjacent to
the OSLM in a reference OSL sensor OSL sensor. In one embodiment of
the present invention, the reference filter material may be in the
form of a disc that is mounted between the OSLM and the base of a
cylindrical-cup shaped filter in which the OSLM is mounted. In one
embodiment of the present invention, the OSLM of a comparator OSL
sensor may be mixed with the reference filter material so that the
OSLM is embedded or suspended in the reference filter material.
[0132] For the purposes of the present invention, the term
"converter material" refers to a converter material that can
convert non-ionizing neutron radiation into recoil or knockout
protons, which can be detected by an OSL sensor or include a
fluorescent nuclear track detector (FNTD). An example of a
"converter material" is high-density polyethylene (HDPE). Another
example of a "converter material" is polyethylene (PE). In some
embodiments of the present invention, a converter material may be
applied as a thin coating on an OSLM or be mounted as a thin film
or disc adjacent to the OSLM of a neutron-sensitive OSLM sensor. In
one embodiment of the present invention, the converter material may
be in the form of a disc that is mounted between the OSLM and the
base of a cylindrical-cup shaped filter in which the OSLM is
mounted. In one embodiment of the present invention, the body of a
dosimeter sled made of a converter material such as HDPE or PE so
that the entire dosimeter sled may act as converter material for an
OSLM or an FNTD mounted in the dosimeter sled. In another
embodiment of the present invention, the OSLM may be mixed with the
converter material so that the OSLM is embedded or suspended in the
converter material.
[0133] For the purposes of the present invention, the term
"cylindrical cup-shaped" refers to a filter having the general
shape of a right cylinder with the top or bottom of the cylinder
removed i.e. the filter has a disc-shaped bottom or top and a
cylindrical wall extending therefrom. The walls, top or bottom may
be formed from the same material or different materials depending
on the angular and energy compensation response to radiation
desired for the dosimeter.
[0134] For the purposes of the present invention, the term
"dosimetric parameter" refers to the value or the number determined
from processing the fluorescent image or signal of irradiated
luminescent material and is directly related to the dose of
radiation absorbed by the detector.
[0135] For the purposes of the present invention, the term "energy
compensating material" refers to a material that when placed
between an OSLM and a source of gamma radiation or x-ray radiation
alters the response over a range of gamma energies or x-ray
energies compared to the OSLM exposed with no compensating or
filtering material. Examples of energy compensating materials are
copper and aluminum.
[0136] For the purposes of the present invention, the term "fast
neutron" refers to the conventional meaning of the term "fast
neutrons", meaning neutrons with energies above 10 keV.
[0137] For the purposes of the present invention, the term "filter"
refers to any structure that is located between a radiation sensing
material, such as an OSLM, and a source of radiation and affects
the radiation experienced by the radiation sensing material. For
example, a filter may be an energy compensating filter, a
converter, a reference filter, a conformal disc etc. In one
embodiment of the present invention, the energy compensating filter
may be a cylindrical cup-shaped filter. Although the filters of the
present invention are primarily described below as being used with
optically stimulated luminescent materials, the filters of the
present invention may be used with other types of radiation sensing
materials, such as thermoluminescent dosimetry (TLD) materials. In
one embodiment of the present invention in which an OSL sensor
comprises an OSLM disc mounted in a cup-shaped filter, one or more
filter material discs may be located between the OSLM disc and the
base of the cylindrical cup-shaped filter. Each of the filter
material discs would constitute a filter.
[0138] For the purposes of the present invention, the term "filter
material" refers the material or materials of which a filter is
comprised. For example, depending on the type of filter, a filter
material may be an energy compensating material, a converter
material, a reference filter material, a conformal material, etc.
Although the filter materials of the present invention are
primarily described below as being used with optically stimulated
luminescent materials, the filter materials of the present
invention may be used with other types of radiation sensing
materials, such as thermoluminescent dosimetry (TLD) materials.
[0139] For the purposes of the present invention, the term "heavy
charged particle (HCP)" refers to nuclei or ions with masses equal
to or greater than a proton. Some representative, but nonlimiting
examples of heavy charged particles include: alpha particles,
tritium ions, protons, recoil protons, etc.
[0140] For the purposes of the present invention, the term
"indirectly ionizing radiation" refers to x-rays, gamma rays or
neutrons.
[0141] For the purposes of the present invention, the term
"ionizing radiation" refers to any particulate or electromagnetic
radiation that is capable of dissociating atoms into a positively
and negatively charged ion pair. The present invention may be used
to determine doses of both directly ionizing radiation and
indirectly ionizing radiation.
[0142] For the purposes of the present invention, the term
"irradiation" refers to the conventional meaning of the term
"irradiation", i.e., exposure to high energy charge particles,
e.g., electrons, protons, alpha particles, etc., or electromagnetic
radiation of wave-lengths shorter than those of visible light,
e.g., gamma rays, x-rays, ultraviolet, etc.
[0143] For the purposes of the present invention, the term "low
penetrating radiation" refers to radiation from heavy charged
particles having penetration range that is less than 100 microns
(100.mu.) in a radiation sensing material or absorber. Examples of
low penetrating radiation are: alpha particles, recoil protons,
etc.
[0144] For the purposes of the present invention, the term "maximum
penetration range" or "penetration range" refers to the distance in
the medium at which a directly ionizing particle comes to rest.
[0145] For the purposes of the present invention, the term
"moderated neutrons" refers to neutrons produced by slowing fast
neutrons by a hydrogen or deuterium containing moderator and having
a large contribution of low energy neutrons in the energy range
from about 0.025 eV to about 10 keV.
[0146] For the purposes of the present invention, the term "neutron
to proton converter" refers to a hydrogen-containing material, such
as high-density polyethylene (HDPE) that may be used to convert
non-ionizing neutron radiation into recoil or knockout protons,
which can be detected by a radiation sensor.
[0147] For the purposes of the present invention, the term
"neutron-sensitive OSL sensor" refers to an OSL sensor that detects
neutrons. A neutron-sensitive OSL sensor may also detect other
types of radiation such as x-ray and gamma rays.
[0148] For the purposes of the present invention, the term "OSL
reader" refers to a device that emits a wavelength of light that
stimulates an OSLM in an OSL sensor to emit light. Under a
specified stimulation regime (continuous stimulation, reading
wavelength and intensity, and pulsed stimulation with various pulse
durations, pulse frequency, pulse shape and time between pulses)
the intensity of the emitted light is proportional to the radiation
exposure in a range from about 0.01 mGy (1 mrem) to over about 100
Gy (10,000 rads).
[0149] For the purposes of the present invention, the term "OSL
sensor" refers to a radiation sensor that is made from or includes
an OSLM. OSL sensors may be read using an OSL reader.
[0150] For the purposes of the present invention, the term "passive
detection" refers to the detection technique that does not require
any active electronic circuitry and a supply of electrical power to
detect the radiation and/or integrate the radiation absorbed
dose.
[0151] For the purposes of the present invention, the term
"penetrating photon radiation" refers to short wavelength
electromagnetic radiation with energies equal to or higher than 10
keV as might originate from radioactive nuclear decay, from space
or produced by accelerating or decelerating of charge particles,
for example, in an X-ray machine or in an accelerator.
[0152] For the purposes of the present invention, the term
"penetrating beta radiation" refers to electrons with energies
equal to or greater than 10 keV as might originate from radioactive
nuclear decay, from space, produced by radiation-induced ionization
of atoms or by acceleration in an electric field.
[0153] For the purposes of the present invention, the term
"portion" refers to any portion of an object or material, including
the entire object and material. For example, a converter that
covers a "portion" of a luminescent material may cover part or all
of one or more surfaces of the luminescent material.
[0154] For the purposes of the present invention, the term
"radiation dosimetry" refers to the conventional meaning of the
term "radiation dosimetry", i.e., the measurement of the amount of
radiation dose absorbed in a material, an object or the body of an
individual.
[0155] For the purposes of the present invention, the term
"radiation sensing material" refers to a material used to sense
radiation in a radiation sensor. Examples of radiation sensitive
materials including optically stimulated luminescent materials for
OSL sensors, thermoluminescent materials for thermoluminescent
dosimetry (TLD) sensors, etc.
[0156] For the purposes of the present invention, the term "recoil
protons" refers to those protons that are generated by the
collision of neutrons with a converter containing a source of
hydrogen atoms, e.g. polyethylene or high-density polyethylene.
[0157] For the purposes of the present invention, the term
"reference filter material" refers to a non-hydrogen containing,
carbon based material with certain optical absorption and
reflection properties that has a filtering effect on x-rays and
gamma rays that is similar to the radiation filtering and optical
absorption and reflection effects of an organic converter material
on x-rays and gamma rays. For example, the "reference filter
material" fluorinated plastic polytetrafluoroethylene (sold under
the trade name Teflon.RTM. by DuPont), which has a filtering effect
on x-rays and gamma rays that is similar to the neutron-to-proton
converter material high-density polyethylene (HDPE). A reference
filter material acts on both optical stimulation and luminescence
light and is used to enhance the effectiveness of the method
according to one embodiment of the present invention.
[0158] For the purposes of the present invention, the term
"reference OSL sensor" is an OSL sensor that includes a reference
filter material and is used to determine the effects of a converter
material on x-ray and gamma ray detection by another OSL sensor
that is identical to the reference OSL sensor, except for the
substitution of the converter material for reference filter
material. In some embodiments of the present invention, the
reference filter material of a reference OSL sensor may be applied
as a thin coating on an OSLM or be mounted as a thin film or disc
adjacent to the OSLM in a reference OSL sensor. In one embodiment
of the present invention, the reference filter material may be in
the form of a disc that is mounted between the OSLM and the base of
a cylindrical-cup shaped filter in which the OSLM is mounted. For
many radiation dosimeters, which employ three OSL sensors arranged
in a row, the best angular response for the radiation dosimeter is
often improved when the reference OSL sensor is the center OSL
sensor. In one embodiment of the present invention, the OSLM of the
reference OSL sensor may be mixed with the reference filter
material so that the OSLM is embedded or suspended in the reference
filter material.
Description
[0159] In existing personal radiation monitoring devices, the
radiation sensors are generally captured in a holder containing one
or more filters that alter the amounts, energies and types of
radiation able to reach the sensors. These filters typically
sandwich the sensors to achieve correct assessments when the
radiation enters the dosimeter from various angles of incidence. To
analyze the sensors, they must be removed from between the filters
and holder and physically presented to the processing system
required to elicit the quantitative attribute exhibited by the
sensor following exposure to radiation.
[0160] For example to analyze a film dosimeter generally involves
the following steps: 1. Removing the film packet from the holder
where it is sandwiched between the filters; 2. Unwrapping
protective packaging that protects the film from light fogging and
physical damage; 3. Developing the films in chemicals; 4. Measuring
the density of the film by placing it between a light source and a
light detector and comparing the transmission of light through the
film to a reference condition where there is nothing placed between
the light source and light detector, and; 5. Relating the density
to radiation exposure in one or more areas of the film
corresponding to the areas where the film was sandwiched between
the filters.
[0161] Similarly radiation sensors based on thermoluminescent
dosimetry (TLD) must be removed from the holder and their position
between the filters and presented to a very high temperature
environment necessary to cause the sensor to emit luminescence and
measure the amount of such luminescence whose intensity is
proportional to the radiation dose. The required temperatures will
typically burn the holder and any identifying labels, thereby
necessitating the removal of the sensors from the TLD dosimeter.
Most common metallic filters also create incandescence and other
interfering light at the very high temperatures, e.g. 200 to
300.degree. C. The disassembly process involves a number of
mechanical steps that create operating inefficiencies. Also,
because of the multiple steps in the disassembly process for a TLD
dosimeter, a complex identification system is required to link a
specific TLD sensor or sensors to the holder that is needed to
establish an unbroken chain of custody whereby the results of the
radiation dose analysis can be related to a particular person or
place being exposed to radiation. The sequence of steps in
disassembling a TLD dosimeter also introduces a risk of damaging or
losing the sensors during the movement of the sensors to the
processing instruments and incorrect reassembly of the dosimeter
when such sensors can be reconditioned for reuse.
[0162] In contrast, radiation sensors based on optically stimulated
luminescence, OSL sensors, only require an optical path whereby a
stimulating beam of light can illuminate the OSL sensor(s) and the
resultant radiation induced luminescence can be routed back through
the same or alternate optical path to a light detector such as a
photomultiplier tube that quantifies the amount of luminescent
light. In one embodiment, the invention employs an optical path
whereby an external beam of light can enter the interior of the
holder, illuminate each OSL sensor and enable the luminescent light
to exit the holder along the same optical path without need to
remove the sensors from their normal position with respect to any
filters or converting materials. The optical path may be either an
optical fiber or an uninterrupted air channel through which light
can travel.
[0163] For more information on OSL materials and systems, see, U.S.
Pat. No. 5,731,590 issued to Miller; U.S. Pat. No. 6,846,434 issued
to Akselrod; U.S. Pat. No. 6,198,108 issued to Schweitzer et al.;
U.S. Pat. No. 6,127,685 issued to Yoder et al.; U.S. patent
application Ser. No. 10/768,094 filed by Akselrod et al.; all of
which are incorporated herein by reference in their entireties. See
also Optically Stimulated Luminescence Dosimetry, Lars
Botter-Jensen et al., Elesevier, 2003; Klemic, G., Bailey, P.,
Miller, K., Monetti, M. External radiation dosimetry in the
aftermath of radiological terrorist event, Rad. Prot. Dosim., in
press; Akselrod, M. S., Kortov, V. S., and Gorelova, E. A.,
Preparation and properties of Al.sub.2O.sub.3:C, Radiat. Prot.
Dosim. 47, 159-164 (1993); and Akselrod, M. S., Lucas, A. C., Polf,
J. C., McKeever, S. W. S. Optically stimulated luminescence of
Al.sub.2O.sub.3:C, Radiation Measurements, 29, (3-4), 391-399
(1998), all of which are incorporated herein by reference in their
entireties.
[0164] Passive sensors, such as film, TLD or OSL sensors as
described above, accumulate and store the dose within the molecular
structure of the sensor without any need of electrical power. This
characteristic makes passive sensors ideal for situations where the
risk of a power interruption is unacceptable. Optically stimulable
crystals and radiation scintillation sensors have been connected to
the ends of fiber optic cables so that the sensors can be attached
to the measurement instrument without removing the sensors from
their locations in the radiation field. The sensors are integrally
sealed to the ends of the optical fiber to prevent stray light from
interfering with the measurement. The optical fibers connect to the
light measurement instrument via a mechanical connector that mates
the fiber to the optical pathway created in the instrument. As a
single sensor is attached to a single fiber, radiation dosimeters
requiring multiple sensors must have multiple fiber connectors that
must be individually linked to the photonics system in the
instrument. The physical size of the connectors and the need to cap
the free end when not joined to the measurement instrument make
dosimeters with multiple fiber leads impractical and inconvenient
for the wearer.
[0165] In one embodiment of the present invention, the design of
the radiation dosimeter enables the OSL sensors to be enclosed with
the dosimeter being analyzed, until the OSL sensors are read. The
radiation dosimeter also provides a means of protecting the OSL
sensors and light path from dirt or other things that may alter or
affect the amount of stimulating and luminescent light able to
travel to and from the OSL sensor(s) and the analytical instrument
(dosimeter reader). The design permits the OSL sensors to be
permanently embedded in a sled so that the sensor(s) can be carried
by the sled to the stimulation light source and luminescence
collector without having to separate the OSL sensors from the sled.
This aids chain of custody because the singularity of the dosimeter
sled and OSL sensors allows the same identification label or tag to
apply to all parts. The design also reduces the number of parts and
mechanical complexity of having a means to open dosimeter so that
sensors can be removed for analysis. Also, because the sled also
contains the filters, the positional arrangement of all the
critical elements of the dosimeter are fixed and not disassembled
for analysis.
[0166] In one embodiment, the present invention eliminates a number
of physical steps thereby improving productivity and enabling
simpler automated handling of large numbers or dosimeters. The
design allows better exploitation of the very fast stimulation and
luminescence processes that make the analysis of optically
stimulated luminescence radiation sensors a very rapid analytical
method, again providing greater productivity in terms of units
analyzed per unit of time. Radiation sensors based on measuring
electrical signals such as current, voltage or resistance that are
changed as a result of exposure to radiation can be connected to a
measurement instrument such as an electrometer, voltmeter or pulse
counter via wires or other types of conducting pathways. Therefore
the sensors may be packaged permanently into the device worn by the
user. Such devices generally require a source of power to establish
the voltage gradients needed to attract the ionization created by
the radiation in the sensor to an electrode or solid-state
collector. These types of devices are generally classed as active
in that they can provide an instantaneous indication of the
radiation exposure rate. If provided a memory capability, active
devices can integrate the rate data to provide an estimate of the
accumulated dose.
[0167] One of the most difficult tasks in radiation dosimetry is
discrimination of the dose created by different radiations,
especially neutrons. Accordingly, the neutrons need to be converted
to directly ionizing radiation, such as alpha particles, energetic
protons, etc., to be detected by such crystals. For dosimetry of
fast neutrons, recoil protons from hydrogen rich plastics, such as
high-density polyethylene, are preferred because they are similar
to the interactions with water that occur in the body. These
converters of neutrons may be associated with, attached to or
otherwise in contact with the luminescent material, may be mixed or
merged with the luminescent material or may be even be part of or
incorporated into the luminescent material. Alpha and beta
particles and protons originated from radionuclides and accelerator
facilities, as well as heavy charged particles of cosmic rays,
usually do not need any conversion.
[0168] In one embodiment of the present invention, each OSL sensor
comprises an assembly composed of one or more cylindrical cups that
act as energy compensating filters that alter the energy or gamma
rays and x-rays able to reach the OSL material (OSLM). The cups can
be formed from one material or have a top and sides of different
materials depending on the angular response desired for the
dosimeter. The thickness of the top and walls may be different from
each other depending on the angular response desired for the
dosimeter. The shape of the cup walls and top need not be flat or
uniform but can be curved and of varying thickness depending on the
angular response desired. The cups may be designed in concert with
the upper and lower housings as these also act as energy
compensating filters.
[0169] In one embodiment of the present invention, the radiation
dosimeter may be worn in a fashion similar to a watch. For such a
radiation dosimeter, the curve structured of the upper housing
combined with the right cylinder cups permits this dosimeter to be
worn on the wrist and still assess the dose to the body as if the
dosimeter were worn on the body.
[0170] In one embodiment of the present invention, the lower
housing contains energy compensating filters that are flat either
as discs aligning with the openings of the cup or as a plate
extending all dimensions of the cup openings. The sequence of the
metal used in the cups imparts the optimum energy shaping as the
lower atomic number elements remove photoelectrons created in the
higher atomic number elements by lower energy x-rays. The
photoelectrons can impart an undesired response in the OSLM. The
cups may be held in place on the sled by compression fit, adhesives
or molded in place so that the sled encompasses the cups.
[0171] When multiple cups are used for one sensor, they can be held
together via a crimping action, compression fit or adhesive. In
many embodiments of the present invention, no more than two cups
would be used with one contained by the other. This keeps the
overall height, cost and assembly at practical values.
[0172] Within the cup are converting filters that convert the
indirectly ionizing radiations into directly ionizing particles,
mainly electrons from gamma rays and x-rays, and recoil protons for
neutrons. In addition, the converters create a reflective condition
whereby the stimulation light passing through the OSLM is reflected
into the OSLM thereby gaining more effective use of the stimulation
light. Similarly, the converters reflect the luminescence light
traveling inwards into the cup back out into the cup opening and
into the light pipe of the photo-engine in the dosimeter
reader.
[0173] In one embodiment of a neutron-sensitive OSL sensor of the
present invention, the thickness of the HDPE converter that
converts the neutrons into recoil protons and the gamma rays/x-rays
into electrons is optimized at 1 mm to create a maximum number of
recoil protons and electrons. A separate thin piece of HDPE may be
added to provide better contact between the OSLM and HDPE.
[0174] In one embodiment of the present invention, the thickness of
the PTFE used in the reference OSL sensor and the comparator OSL
sensor is such that it converts the gamma rays/x-rays into a
similar number of electrons. In this case its thickness is also 1
mm. The tolerance of the thicknesses of both converters may be
.+-.0.1 mm.
[0175] The converters and filters may be retained inside the cups
either by adhesives, compression fit or retaining rings that also
retain the OSLM in contact with the converters. The retaining ring
may be a 0.6 mm diameter wire that fully wraps around the interior
diameter of the inner cup. The retaining ring defines the optical
readout area of the stimulation light illuminating the OSLM.
[0176] Although the converters and filters described below and
shown in the drawings are flat in other embodiments, the converters
may be parabolic to enhance the optical reflection into the light
pipe but with added cost.
[0177] The combined construction of the energy compensating filter
cups and radiation converting filters is such that when mounted
into the sled, all of the OSLM is at the same height in the sled
and therefore the same distance from the exit of the light pipe of
the optical engine.
[0178] Each sensor may be individually calibrated as the reflection
and light absorption properties of the HDPE and PTFE are slightly
different. This also permits visual distinction of the sensors
needed for accurate assembly of the dosimeter.
[0179] The grain size of the aluminum oxide particles in an OSLM
according to one embodiment of the present invention may be
selected based on the range of the recoil protons in the aluminum
oxide. Based on Monte Carlo simulations and experimental
confirmation tests, this grain size is between 30 and 40 microns
for the fast neutron environments of most concern in radiation
protection dosimetry. Once the recoil protons have deposited their
energy in the aluminum oxide grain, any greater size would not
increase the proton response but since the electrons have a greater
range, the response due to the gamma rays/x-rays would increase
thereby reducing the neutron to gamma ray/x-ray signal ratio.
Conversely, smaller grains would not fully capture the recoil
proton energy thereby also reducing the neutron to gamma ray/x-ray
signal ratio.
[0180] The coating of the aluminum oxide grains onto a clear film
may be done with binders that have minimal hydrogen so that the
reference sensor response is only due to gamma rays and x-rays.
[0181] In one embodiment of the present invention, a minimal binder
coating is used on top of the grains so as to not to interfere with
the recoil protons depositing their energy into the aluminum
oxide.
[0182] In one embodiment of the present invention, the film on
which the aluminum oxide is coated may be transparent to blue and
green light and have a thickness ranging between 0.05 and 0.15
mm.
[0183] In one embodiment of the present invention, the OSL sensors
are mounted in a dosimeter sled that slides in contact with the
plate in the OSL reader to which a photo-optical engine of the
present invention is attached. The dosimeter sled, combined with
the OSL sensors, maintains the OSLM material in each of the OSL
sensors at a constant distance from the exit of the optical light
pipe of the OSL reader to assure uniform stimulation and collection
of luminescence light. In one embodiment of the present invention,
an end side of the dosimeter sled is curved to ensure that the
circular optical light pipe is completely blocked when the OSL
sensor mounted closest to the curved end side is read.
[0184] In one embodiment of the present invention, the dosimeter
sled in which the OSL sensors are mounted may be made of PE or HDPE
allowing part of its surface to be used to convert the neutrons to
recoil protons in that area where the FNTD sensor is mounted on the
underside recess in the sled.
[0185] In one embodiment of the present invention, the centers of
each sensor may be aligned along a straight line parallel to the
long axis of the sled and along the axis of travel into and out of
the rail system in the OSL reader of the dosimeter reader that
guides the slide and in turn the sensors over the light pipe of the
photo-engine in the OSL reader.
[0186] In one embodiment of the present invention, the dosimeter
sled may be engraved with an identification number that is
reproduced in an RFID tag.
[0187] In one embodiment of the present invention, the dosimeter
sled has a recess over the comparator OSL sensor where the RFID tag
is placed. The RFID tag may be held in place by an adhesive
transfer tape such as 3M adhesive tape with 300SLE adhesive or
alternatively with a UV curable adhesive liquid placed along the
edge of the tag. The placement of the RFID tag is such that the
metal filters do not impede the RF field created by the RFID tag
reader thereby permitting correct reading and writing to the RFID
tag.
[0188] In one embodiment of the present invention, the OSL sensors
are mounted in openings in the dosimeter sled that include
respective ledges that locate the height of the OSL sensors. The
combination of these ledges and the cylindrical-cup shaped filters
are also designed to maintain the OSLM in each OSL sensor at the
same height.
[0189] In one embodiment of the present invention, in addition to
the three OSL sensors described above, the radiation dosimeter may
also include a fluorescent nuclear track detector (FNTD) mounted in
the dosimeter sled. The FNTD provides an alternative method of
dosimetry under alternate conditions of analysis. Examples of
suitable fluorescent nuclear track detectors are described in U.S.
patent application Ser. No. 12/258,035 to Akselrod, et al.,
entitled "METHOD OF LUMINESCENT SOLID STATE DOSIMETRY OF MIXED
RADIATIONS" filed Oct. 24, 2008, the entire contents and disclosure
of which is incorporated herein by reference.
[0190] In some embodiments of the present invention, in addition to
the three OSL sensors described above or in place of one of the OSL
sensors described above, the dosimeter sled may include an OSL
sensor that has a second type of OSLM that is different from the
OSLM in the other OSL sensors.
[0191] In one embodiment of the present invention, the underside of
the dosimeter sled may include a recess that houses an FNTD
(fluorescence nuclear track detector) or a polyallyldicarbonate
plastic (PADC sold under the trade name CR-39) to alternately
assess the dose from neutrons. Within the recess are two wells into
which are placed a piece of PTFE and a piece of LiF or Li loaded
plastic. These align with the upper surface of the recess creating
a uniform surface on which the FNTD or PADC is placed. They are
held into place either by a compression fit or with an adhesive.
The PTFE acts as a reference converter in a way similar to its role
with the OSL sensors. The HDPE surface created by the sled acts as
a neutron converter similar to the way that an HDPE disc may be
used as a converter material disc in an neutron-sensitive OSL. The
lithium converter preferentially converts thermal and slow energy
neutrons into recoil alpha particles and tritium ions from the
Li-6(n,.alpha.)H-3 reaction. Both the FNTD and the PADC are held in
place by small tabs that hook over the edges of the sensors. The
FNTD or PADC may be engraved with ID numbers matching that of the
sled and RFID tag.
[0192] In one embodiment of the present invention, the long sides
of the dosimeter sled have protruding rails that are inserted into
corresponding slots in the lower housing. The rails have beveled
edges to permit easy movement into and out of the lower housing and
provide a space for small amounts of dirt or dust to accumulate
without impeding the sliding motion.
[0193] One rail has semicircular notches that align with the
centers of each of the sensors. These permit a photodiode to sense
when the sled is in the correct position for analysis in the OSL
reader. The correct position is that which allows the stimulation
light to fully illuminate the area of the OSLM in the sensor.
[0194] The trailing edge of the sled has a semicircular edge that
provides extra light protection when reading the third sensor in
the OSL reader. The rounded edge provides added extension of the
sled beyond the edge of the light pipe thereby preventing stray
light from entering the light pipe from the trailing edge of the
sled into and out of the OSL reader. Some embodiments may omit this
feature.
[0195] The leading edge has a U-shaped detent and a tang that
engages with a tang and U-shaped detent, respectively, on a slider
that pulls the dosimeter sled into and out of the housing for the
OSL reader.
[0196] The openings over the sensors permit visual and electronic
verification of the correct placement of the sensors by automated
assembly equipment. An electrical contact is made to verify correct
placement and a color sensor may be used to verify that a filter of
a sensor is copper instead of aluminum or vice versa.
[0197] The upper housing is circular but may have molded facets to
provide visual differentiation as to where the dosimeter is to be
worn, e.g. circle for wrist, hexagonal facets for wearing on the
body, etc.
[0198] The upper housing may have opposed loops of slots into which
a strap of belt may be inserted for wearing on the wrist or other
body part. One loop may be omitted so that a clip is inserted
through the slot for attachment to clothing like an identification
badge.
[0199] The housing will have a product identification or model
number embossed or engraved.
[0200] The housing may have an alignment symbol to aid in properly
positioning the dosimeter onto the dosimeter drawer of the
dosimeter reader.
[0201] The housing may have a curved arrow showing the direction of
rotation to disengage the threads holding the upper and lower
housings together.
[0202] The housing may be constructed of polyoxymethylene (POM
trade name Delrin.RTM. by Dupont), polycarbonate (Lexan),
acetylbutylstyrene (ABS) or other suitable plastic material.
[0203] The upper housing will have a flat inner surface at an angle
of 15 to 25 degrees from the bottom plane of the housing below the
threads that will mate to a sealing material located on the lower
housing so as to provide a watertight seal.
[0204] The upper housing will be threaded so that a 90.degree.
counterclockwise rotation will disengage the housing from the lower
housing permitting the two pieces to be separated from each
other.
[0205] In one embodiment, the present invention provides a
radiation dosimeter with three OSL sensors: (1) a neutron-sensitive
OSL sensor that senses gamma, x-ray and neutron radiation, (2) a
reference sensor that senses only x-ray and gamma radiation and (3)
a comparator OSL sensor for the reference sensor. The
neutron-sensitive OSL sensor includes an OSLM that is mounted in an
inner filter made of a first energy compensating material, such as
aluminum. The inner filter is in turn mounted in an outer filter
made of a second energy compensating material, such as copper.
Placed between the inner compensating filter and the OSLM, either
as a thin disc, thin layer or thin coating, is a converter
material, such as high-density polyethylene, that converts neutrons
into recoil protons that can be sensed by the neutron-sensitive OSL
sensor. The reference OSL sensor is identical to the
neutron-sensitive OSL sensor, except that instead of the converter
material being placed between the inner compensating filter and the
OSLM, a reference filter material, such as polytetrafluoroethylene,
is placed between the inner compensating filter and the OSLM either
as a thin disc, a thin layer or as a thin coating on the OSLM. The
comparator OSL sensor is identical to the reference OSL sensor,
except that the comparator OSL sensor does not include the outer
filter of the reference OSL sensor.
[0206] In one embodiment, the neutron-sensitive OSL sensor, the
reference OSL sensor, and the comparator OSL sensor may be mounted
in a dosimeter sled that may be slid out of the radiation dosimeter
to allow the three OSL sensors to be read using an OSL reader. The
design of the dosimeter sled allows the three OSL sensors to be
read from the same side, the exposed side of each OSL sensor where
there is no filter covering the OSLM of the OSL sensor. Although in
the embodiments shown below, the three OSL sensors are mounted in
the dosimeter sled in the order: (1) neutron-sensitive OSL sensor,
(2) reference OSL sensor, and (3) comparator OSL sensor, the three
OSL sensors may be mounted in the dosimeter sled in any order.
[0207] In one embodiment of the present invention, the OSLM used in
the OSL sensors is a specialized carbon-doped aluminum oxide
(Al.sub.2O.sub.3:C) material manufactured by Landauer, Inc.
(Glenwood, Ill.), and is similar to that marketed in dosimeters
with trade names LUXEL+ and INLIGHT. The OSLM consists of specially
formulated, proprietary, powderized Al.sub.2O.sub.3:C. For use in
the OSL sensors of the present invention, the Al.sub.2O.sub.3:C
material may be in the form a disc-shaped pellet.
[0208] Exposure of the Al.sub.2O.sub.3:C material in each of the
three OSL sensors to ionizing radiation releases electrons that are
trapped in defects in the material's crystal structure. The
electrons are released from the traps when stimulated with
520.+-.10 nm wavelength light (i.e. green). As they return to the
ground state, 420.+-.10 nm wavelength light (i.e. blue) is emitted.
It should be noted that other light wavelengths could be employed,
as could a pulsed stimulation system in reading the OSL sensors of
the present invention.
[0209] The dosage of gamma ray and x-ray radiation received by the
dosimeter and the individual who has been wearing the dosimeter may
be determined from the emitted light from the second or reference
OSL sensor and may be modified based on the results of reading the
third comparator OSL sensor. The dosage of neutron radiation may be
determined by subtracting the dosage value from reading the second
OSL sensor from the dosage value from reading the first OSL sensor
and multiplying the result by a calibration factor appropriate for
the expected neutron energy spectrum.
[0210] In one embodiment of the present invention, a radiation
dosimeter or part of a dosimeter, such as a dosimeter sled,
includes an RFID tag. The RFID tag includes a radiofrequency (RF)
antenna that allows the RFID tag to communicate with the RF antenna
of an RFID tag reader to allow information/data to be read from the
RFID tag by the RFID tag reader and to allow the RFID tag reader to
store information on the RFID tag. In one embodiment of the present
invention, the RFID tag includes a non-volatile data storage
device, such as flash memory, that allows the RFID tag to store
information about the radiation dosimeter and the wearer of the
radiation dosimeter that enables the reading out of the radiation
dosimeter by any reader without having to access a database to
retrieve data needed to calculate the dose. When the RFID tag is
part of a dosimeter sled, the RFID tag may be read while the sled
is in the dosimeter. The dosimeter does not need to be disassembled
nor the dosimeter sled removed to read data from and/or write data
to the RFID tag. The RFID tag may be read when the dosimeter sled
is in a reading position for one of the OSL sensors of the
dosimeter sled or at a separate reading position for the RFID
tag.
[0211] Although the RFID tag of the present invention is described
for use with particular radiation dosimeters in the embodiments of
the present invention are described below, the RFID tag may also be
used with other types of radiation dosimeters. For example, the
RFID tag may be used with badge-type, case-type and slide-type
radiation dosimeters manufactured and sold by Landauer, Inc under
the trade name InLight.TM.. The RFID tag may also be used with
radiation dosimeters employing a variety of dosimeter materials
and/or dosimeter reading methods, including the dosimeter materials
and dosimeter reading method described in: U.S. Pat. No. 5,354,997
to Miller, entitled "Method for Increased Sensitivity of Radiation
Detection and Measurement," issued Oct. 11, 1994; U.S. Pat. No.
5,567,948 to Miller, entitled "Composite Material Dosimeters,"
issued Oct. 22, 1996; U.S. Pat. No. 5,569,927 to Miller, entitled
"Composite Material Dosimeters," issued Oct. 29, 1996; and U.S.
Pat. No. 5,731,590 to Miller, entitled "Metal Oxide Composite
Dosimeter Method and Material," issued Mar. 24, 1998, and the
entire contents and disclosures of these patents are incorporated
herein by reference.
[0212] The RFID tag may store the results of the last several
readouts, thereby enabling the dose history experienced by the
wearer to be retrieved. The RFID tag may carry identification, date
and time data to establish a chain of custody regarding who was
assigned the dosimeter and when certain actions were performed on
the dosimeter. In one embodiment of the present invention, the RFID
tag may carry the following information: identification information
for the dosimeter model, dosimeter serial number and an
identification number for the individual to whom the dosimeter is
assigned, calibration data for each OSL sensor, date and time
information needed to estimate the buildup of background radiation
dose, the total radiation dose and the dose from gamma rays and the
dose from neutrons, date and time information regarding the
assignment of the dosimeter to an individual, date and time
information when the dosimeter was readout, and reader quality
control data depicting the operability of the dosimeter reader
during the analysis of the dosimeter including the unique reader
identification number.
[0213] The RFID tag of the present invention may be read and
written to using an appropriate RFID antenna and deciphering code
either by the dosimeter reader or by a stand-alone RFID tag reader
connected to a PC or other data input device. When the dosimeter is
returned to a laboratory from the field, the dose results may be
separately read out to verify the field results and the recent
history of the dosimeter results obtained in the field reviewed to
establish an accredited radiation dose record for archiving.
[0214] In one embodiment of the present invention, the RFID tag
enables the dosimeter to be analyzed in remote areas where there is
no access to databases containing information needed for the
correct analysis of the dosimeter. The RFID tag carries the history
of the analysis of the dosimeter so that a dose reconstruction can
be performed. The RFID tag has a limited range of readout to avoid
detection of the dosimeter during covert operations.
[0215] In one embodiment, the dosimeter reader may communicate with
a database separated from the dosimeter reader. The dosimeter
reader may communicate with the separate database in a variety of
ways such as: wireless communication, communicating via an optical
fiber, communicating over a wire, communicating over the Internet,
communicating over a phone line, etc.
[0216] In some embodiments of the present invention a dosimeter may
be given to and worn by an individual before the dosimeter is
assigned to the individual in the database. In such cases, the
database may be updated with the name and other identification such
as social security number, dog tag number, etc., for the individual
to whom the dosimeter has been assigned at a later date. The
database may even be updated the first time that the dosimeter is
read by a dosimeter reader.
[0217] In one embodiment, the dosimeter reader of the present
invention is battery operated and can be moved during analysis. The
dosimeter reader displays the results of the analysis, performs
Pulsed Optically Stimulated Luminescence (POSL) processes, stores
results of analyses, writes results of dosimeter analysis to an
RFID chip on the dosimeter sled, has an output mechanism, such as a
USB plug, whereby data may be downloaded into a remote database or
PC and reader settings may be uploaded to the dosimeter reader. The
dosimeter reader may be light-weight and/or water-tight and/or
floatable. The dosimeter reader may be read out at various angles
from the horizontal and includes a display and buttons for
operation.
[0218] In one embodiment of the present invention, the dosimeter
reader includes stimulation light monitoring and ambient light
monitoring. Stimulation light monitoring may be conducted by a
photodiode to which a fraction of the stimulation light is routed.
The response of the photodiode is monitored and compared to a
reference value obtained for the correct stimulation light level.
Ambient light monitoring may be conducted by performing the
luminescence counting routine without applying any stimulation
light to the OSL sensor. The dosimeter reader of the present
invention may employ pulses of varying duration and frequency. The
dosimeter reader may also check for luminescence intensity to
select an alternative POSL scheme. Luminescence intensity may be
used to select an alternative POSL scheme by performing the
analytical process for a small fraction of the normal analysis time
and comparing the result to a reference value that instructs the
reader to operate the stimulation light at a given frequency and
pulse duration that increases or decreases the luminescence light
created by the stimulation light thereby maintaining an optimum
amount of light for the light sensing system e.g. photomultiplier
tube. The measurement off the luminescence intensity may be very
brief, i.e. less than about 10% of the time required to read an OSL
sensor.
[0219] FIGS. 1 and 2 show a radiation dosimeter 102 according to
one embodiment of the present invention including an upper housing
104 and a lower housing 106 mounted in upper housing 1. FIG. 1
shows bottom 112 of radiation dosimeter 102, and FIG. 2 shows top
114 of dosimeter 102. Upper housing 104 includes a circular body
120 and two generally trapezoidal-shaped loops 122 and 124 located
on respective opposite sides 126 and 128 of circular body 120. A
dashed orientation line 130 is shown drawn through the middle of
and perpendicular to loops 122 and 124. Lower housing 106 has three
circular recesses 142, 144 and 146 between opposite sides 148 and
150 of lower housing 106. A dashed orientation line 152 is shown
drawn through the middle of circular recesses 142, 144 and 146.
[0220] FIGS. 2 and 3 show upper housing top 202 and upper housing
bottom 204 of upper housing 104. Upper housing top 202 corresponds
to top 114 of radiation dosimeter 102. Loops 122 and 124 have
respective openings 216 and 218 through which a strap member (not
shown) may be threaded so that radiation dosimeter 102 may be worn
on the wrist of an individual. Upper housing top 202 has a flat
circular upper surface 220 and includes a curved arrow 222 and a
circular alignment symbol 224. Also included on upper housing 104
are etched alphanumeric identification indicia 232. Circular
interior wall 234 of upper housing bottom 204 includes interior
screw threads 236. Interior wall 234 surrounds a circular recess
242 with a flat bottom 244.
[0221] The Identification indicia may identify the radiation
dosimeter and/or the individual wearing the radiation
dosimeter.
[0222] The body of upper housing of FIGS. 2 and 3 is made of
polyoxymethylene (POM) sold under the trade name Delrin.RTM. by
Dupont. However, in other embodiments, the body of the upper
housing may be made of polycarbonate, polyethylene, styrene or
other durable plastic materials.
[0223] FIGS. 4 and 5 show a lower housing top 400 and a lower
housing bottom 402 of lower housing 106. Lower housing 106 has a
circular base 404 and an upper structure 406. Upper structure 406
has a circular exterior wall 408 that has screw threads 410 spaced
around the circumference thereof. Lower housing top 400 includes a
generally punch card-shaped sled recess 412 having two opposite
lateral sides 414 and 416, an end wall 418 perpendicular to lateral
sides 414 and 416, a slanted corner wall 420 and an open end 422.
Lateral side 414 includes an indentation 424. Lateral side 416
includes an indentation 426. Lateral side 414 includes a groove 432
and an upper lip 434 that run along the length of lateral side 414.
Lateral side 416 includes a groove 436 and an upper lip 438 that
run along the length of lateral side 416. Lower housing upper
structure 406 includes an upper flat surface 442 and a lower flat
surface 444. Lower flat surface 444 is exposed by sled recess 412
and the absence of upper flat surface 442 in exposed edge region
448. Lower housing bottom 402 has a flat bottom surface 452,
circular recesses 142, 144 and 146, a C-shaped groove 454 and two
lozenge-shaped recesses 456 and 458. Opposite ends 462 and 464 of
C-shaped groove 454 are separated by a gap 466. Respective circular
copper filter discs 472 and 474 are inserted in circular recesses
142 and 144 and serve as energy compensating filters. Copper filter
discs 472 and 474 are held in place in circular recesses 142 and
144 by press fitting, by being molded in place or by using an
adhesive.
[0224] The body of the lower housing of FIGS. 4 and 5 is made of
polyoxymethylene (POM) sold under the trade name Delrin.RTM. by
Dupont. However, in other embodiments, the body of the lower
housing may be made of polycarbonate, polyethylene, styrene or
other durable plastic materials.
[0225] FIGS. 6 and 7 show dosimeter sled 600 according to one
embodiment of the present invention including a sled body 602, a
sled top face 604 and a sled bottom face 606 that are opposite each
other. Sled body 602 includes three openings 608, 610 and 612.
Openings 608, 610 and 612 include respective top portions 614, 616
and 618 and respective bottom portions 620, 622 and 624. A
neutron-sensitive OSL sensor 626, a reference OSL sensor 628 and a
comparator OSL sensor 630 are mounted in openings 608, 610 and 612,
respectively, and are held in place by pressing neutron-sensitive
OSL sensor 626, reference OSL sensor 628 and comparator OSL sensor
630 into sled body 602. Because top portions 614, 616 and 618 are
smaller than respective bottom portions 620, 622 and 624 of
respective openings 608, 610 and 612, neutron-sensitive OSL sensor
626, reference OSL sensor 628 and comparator OSL sensor 630 abut
respective circular ledges (not visible in FIGS. 6 and 7) formed
openings 608, 610 and 612 by top portions 614, 616 and 618,
respectively.
[0226] Although the OSL sensors in the embodiment of the present
invention of FIGS. 6 and 7 are held in the sled by press fitting,
in other embodiments the OSL sensors may be held in place with an
adhesive. In other embodiments, the OSL sensors may be molded in
place so that the OSL sensors are each fully captured by the
plastic sled.
[0227] Neutron-sensitive OSL sensor 626 includes a disc-shaped
pellet of OSLM 632, a converter material disc (not visible in FIGS.
6 and 7), a cylindrical cup-shaped inner filter 634 and a
cylindrical cup-shaped outer filter 636. OSLM 632 and the converter
material disc are held in place in inner filter 634 by a retaining
ring 637. The converter material disc is sandwiched between OSLM
632 and inner filter 634. Retaining ring 637 is a spring-type
retaining ring and is held in place in inner filter 634 by
compression. When retaining ring 637 is compressed in inner filter
634, ends 638 and 639 of retaining ring 637 abut each other. Inner
filter 634 is mounted and held in outer filter 636 by press fitting
inner filter 634 into outer filter 636. OSLM 632 has a filtered
side (not visible in FIGS. 6 and 7), the side of OSLM 632 filtered
by the converter material disc, inner filter 634 and outer filter
636. Neutron-sensitive OSL sensor 626 has an exposed side 640,
shown in FIG. 7, which allows the combined dosage of x-ray, gamma
and neutron radiation to which OSLM 632 has been exposed to be read
by an OSL reader. Retaining ring 637 is mounted on exposed side 640
of OSLM 632. OSLM 632 comprises an Al.sub.2O.sub.3:C material.
Inner filter 634 is made of aluminum. Outer filter 636 is made of
copper. Retaining ring 637 is made of stainless steel. The
converter material disc is a thin disc made of high-density
polyethylene.
[0228] Reference OSL sensor 628 includes a disc-shaped pellet of
OSLM 642, a reference filter material disc (not visible in FIGS. 6
and 7), a cylindrical cup-shaped inner filter 644 and a cylindrical
cup-shaped outer filter 646. OSLM 642 and the reference filter
material disc are held in place in inner filter 644 by a retaining
ring 647. The reference filter material disc is sandwiched between
OSLM 642 and inner filter 644. Retaining ring 647 is a spring-type
retaining ring and is held in place in inner filter 644 by
compression. When retaining ring 647 is compressed in inner filter
644, ends 648 and 649 of retaining ring 647 abut each other. Inner
filter 644 is mounted and held in outer filter 646 by press fitting
inner filter 644 into outer filter 646. OSLM 642 has a filtered
side (not visible in FIGS. 6 and 7), the side of OSLM 642 filtered
by the reference filter material disc, inner filter 644 and outer
filter 646. OSLM 642 has an exposed side 650 that establishes an
optical pathway, shown in FIG. 7, which allows the combined dosage
of x-ray and gamma radiation to which OSLM 642 has been exposed to
be read by an OSL reader. Retaining ring 647 is mounted on exposed
side 650 of OSLM 642. OSLM 642 comprises an Al.sub.2O.sub.3:C
material. Inner filter 644 is made of aluminum. Outer filter 646 is
made of copper. Retaining ring 647 is made of stainless steel. The
reference filter material disc is a thin disc made of
polytetrafluoroethylene.
[0229] Comparator OSL sensor 630 includes a disc-shaped pellet of
OSLM 652, a reference filter material disc (not visible in FIGS. 6
and 7), and a cylindrical cup-shaped filter 654. OSLM 652 and the
reference material filter disc are held in place in filter 654 by a
retaining ring 655. The reference filter material disc is
sandwiched between OSLM 652 and filter 654. Retaining ring 655 is a
spring-type retaining ring and is held in place in inner filter 644
by compression. When retaining ring 655 is compressed in filter
654, ends 656 and 657 of retaining ring 655 abut each other. OSLM
652 has a filtered side (not visible in FIGS. 6 and 7), the side of
OSLM 652 filtered by the reference filter material disc and filter
654. OSLM 652 has an exposed side 658, shown in FIG. 7, which
allows the combined dosage of x-ray and gamma radiation to which
OSLM 652 has been exposed to be read by an OSL reader. Retaining
ring 655 is mounted on exposed side 658 of OSLM 652. OSLM 652
comprises an Al.sub.2O.sub.3:C material. Filter 654 is made of
aluminum. Retaining ring 655 is made of stainless steel. The
reference filter material disc is a thin disc made of
polytetrafluoroethylene.
[0230] Neutron-sensitive OSL sensor 626 is identical to reference
OSL sensor 628, except for the substitution of the
polytetrafluoroethylene disc in reference OSL sensor 628 for the
high-density polyethylene disc in neutron-sensitive OSL sensor 626.
Comparator OSL sensor 630 is identical to reference OSL sensor 628,
except that filter 654 is not mounted in an outer filter. In
comparator OSL sensor 630, filter 654 functions as an outer
filter.
[0231] Neutron-sensitive OSL sensor 626, reference OSL sensor 628
and comparator OSL sensor 630 are similar to each other in that
they have the same OSLM disc, the same cylindrical cup-shaped inner
filter and the same retaining ring. Neutron-sensitive OSL sensor
626, reference OSL sensor 628 and comparator OSL sensor 630 also
each include a disc of filter material sandwiched between the OSLM
disc and the inner filter. This similarity in the components making
up each of the OSL sensors maintains a consistent optical condition
of reflection and scattering of the stimulation and luminescence
light within the sensor.
[0232] Mounted in a nearly circular recess 659 in sled top face 604
is a round Radio Frequency ID (RFID) tag 660. RFID tag 660 is held
in place in recess 659 by a double-sided contact adhesive film
manufactured by 3M. RFID tag 660 includes an antenna 661 and a
memory chip 662. Sled body 602 has two parallel lateral sides 663
and 664, two parallel straight end sides 666 and 668, and two
slanted corner sides 670 and 672. Between neutron-sensitive OSL
sensor 626 and straight end side 666 end is a region 673. Lateral
side 663 includes a rail 674 along the length of lateral side 663
on the bottom half of lateral side 663. Rail 674 protrudes from
lateral side 663. Lateral side 664 includes a rail 676 along the
length of lateral side 664 on the bottom half of lateral side 664.
Rail 676 protrudes from lateral side 664. Lateral side 663 includes
a U-shaped detent 678 and a tang 679 near end side 668. Rail 674
includes three semicircular positioning notches 680, 682 and 684.
Sled bottom face 606 includes a recess 686 including indentations
688, 690, 692, 694 and 696. Sled top face 604 includes alphanumeric
identification indicia 698 that match alphanumeric identification
indicia 232 on upper housing 104.
[0233] Although a double-sided contact adhesive film is used to
hold the RFID tag in place on the dosimeter sled in embodiment of
the present invention are described above and shown in FIGS. 6 and
7, the RFID tag may be held on the dosimeter sled by other means.
For example, the RFID tag may be adhered to the dosimeter sled
using a UV cured adhesive placed along the outside of the RFID
tag.
[0234] In one embodiment of the present invention, when OSL sensors
626, 628 and 630 are being read in turn by a dosimeter reader,
positioning notches 680, 682 and 684 may be used to properly
position each OSL sensor in turn within an OSL reader. Positioning
notch 680 may be used to properly position neutron-sensitive OSL
sensor 626 within the dosimeter reader. Positioning notch 682 may
be used to properly position Reference OSL sensor 628 within the
OSL reader. Positioning notch 684 may be used to properly position
comparator OSL sensor 630 with the dosimeter reader.
[0235] In one embodiment of the present invention, the positioning
notches may be used to align the OSL sensors with the optical path
of the OSL reader so that the stimulation light and luminescence
light are consistently applied and captured. As the dosimeter sled
is moved into the OSL reader, the notches open up a light path for
a photo-optic sensor to complete an electrical circuit whereby the
dosimeter reader control system knows that the OSL sensor is
correctly positioned over the photo-engine of the OSL reader to
permit analysis.
[0236] FIG. 8 shows reference OSL sensor 628 in a disassembled
state with inner filter 644 removed from outer filter 646. FIG. 9
shows reference OSL sensor 628 in an assembled state with inner
filter 644 mounted in outer filter 646. Not visible in FIGS. 8 and
9 is the disc of polytetrafluoroethylene sandwiched between OSLM
642 and inner filter 644. Due to glare in the images of FIGS. 8 and
9, retaining ring 647 is not easily visible in FIGS. 8 and 9.
[0237] In FIG. 8, the combination of OSLM 642, the
polytetrafluoroethylene disc (not visible in FIG. 8), inner filter
644 and retaining ring 647 also corresponds to the assembled state
of comparator OSL sensor 630.
[0238] FIG. 10 shows dosimeter sled 600 being slid into sled recess
412 of lower housing 106. Rail 674 of dosimeter sled 600 slides in
groove 432 beneath upper lip 434 of lower housing 106. Rail 676 of
dosimeter sled 600 slides in groove 436 beneath upper lip 438 of
lower housing 106.
[0239] FIG. 11 shows dosimeter sled 602 fully slid into sled recess
412 so that end side 666 of dosimeter sled body 602 abuts end wall
418 of lower housing 106 and slanted corner side 670 of dosimeter
sled 602 abuts corner wall 420 of lower housing 106, i.e.,
dosimeter sled 602 has a shape that complementarily fits sled
recess 412. In the configuration shown in FIG. 11, dosimeter sled
602 is considered "mounted" in lower housing 106. In the
configuration shown in FIG. 11, copper filter discs 472 and 474 of
lower housing 106 are positioned directly below neutron-sensitive
OSL sensor 626 and reference OSL sensor 628, respectively of
dosimeter sled 602 and circular recess 146 of lowering housing 106
is positioned directly below comparator OSL sensor 630 of dosimeter
sled 602.
[0240] There is no copper filter disc in circular recess 146,
because comparator OSL sensor 630 may be used to adjust the dose
determined by reference OSL sensor 628 at very low energies of
x-rays. Therefore, unlike for neutron-sensitive OSL sensor 626 and
reference OSL sensor 628, it is undesirable for there to be a
filter mounted in lower housing bottom 402 beneath comparator OSL
sensor 630.
[0241] In an alternative embodiment of the present invention,
instead of using two copper filter discs, a rectangular filter
plate may be mounted in a rectangular plate recess in the sled
recess of the lower housing. As with the copper filter discs, the
filter plate shields are located between the neutron-sensitive OSL
sensor and the reference OSL sensor when the dosimeter sled is
fully slid into the sled recess. By mounting the filter plate in a
less exposed position in the lower housing, the filter plate is
better protected than the copper filter discs which are externally
exposed on the bottom of the lower housing of the dosimeter.
[0242] Lower housing 106, with dosimeter sled 602 slid/mounted
therein, may be mounted in upper housing 104 by screwing lower
housing 106 into upper housing 104 using threads 236 of upper
housing 104 and screw threads 410 of lower housing 106. Lower
housing 106 is held in place in upper housing 104, when orientation
line 130 of upper housing 104 is parallel to orientation line 152
of lower housing 106. Upper housing 104 can be separated from lower
housing 106 by grasping loops 122 and 124 and turning upper housing
90.degree. counterclockwise so that upper housing 104 and lower
housing are oriented as shown in FIG. 1. In the configuration shown
in FIG. 1, orientation line 130 is perpendicular to orientation
line 152 and upper housing 104 is in a released position relative
to lower housing 106.
[0243] FIGS. 12, 13, 14, 15 and 16 show an upper housing 1200 of a
radiation dosimeter according to one embodiment of the present
invention. FIGS. 12 and 14 show upper housing top 1202. FIGS. 13
and 15 show upper housing bottom 1204. Upper housing 1200 includes
a circular body 1206 and two generally trapezoidal-shaped loops
1212 and 1214 located on respective opposite sides 1216 and 1218 of
circular body 1206. Loops 1212 and 1214 have respective openings
1226 and 1228 through which a strap member (not shown) may be
threaded so that the dosimeter may be worn on the wrist of an
individual. Upper housing top 1202 has a circular contoured portion
1230 and a flat circular upper surface 1232 and includes a curved
arrow 1242, a circular alignment symbol 1244 and a shallow rounded
rectangular recess 1246. In one embodiment of the present
invention, a label with alphanumeric identification indicia (not
shown) may be adhered to upper housing top 1202 in shallow rounded
rectangular recess 1246. In another embodiment of the present
invention, alphanumeric identification indicia (not shown) may be
engraved in shallow rounded rectangular recess 1246. Circular
interior wall 1254 of upper housing bottom 1204 includes interior
screw threads 1256. Interior wall 1254 surrounds a circular recess
1262 with a flat bottom 1264.
[0244] FIGS. 17, 18, 19, 20, 21, 22, 23 and 24 show a lower housing
1700 according to one embodiment of the present invention. FIGS. 17
and 19 show a lower housing top 1702. FIGS. 18 and 20 show a lower
housing bottom 1704. Lower housing 1700 includes a circular lower
housing base 1706, a circular disc-shaped platform 1708 having a
circular lower exterior wall 1710 that has screw threads 1712
spaced around the circumference thereof. Platform 1708 has a flat
upper surface 1714 with a rectangular filter plate recess 1716. A
thin rectangular energy compensating filter plate (not shown FIGS.
17, 18, 19, 20, 21, 22, 23 and 24) may be mounted in filter plate
recess 1716. On top of upper surface 1714 are two upper structures
1718 and 1720, which have respective upper surfaces 1722 and 1724.
Upper structure 1718 includes a curved exterior rail 1726. Upper
structures 1718 and 1720 define a sled recess 1728 having two
opposite lateral sides 1730 and 1732, an end wall 1734, a slanted
corner wall 1736 and an open end 1738. End wall 1734 includes a
curved wall portion 1740. Lateral side 1730 includes an indentation
1744. Lateral side 1732 includes an indentation 1746. Lateral side
1730 includes a groove 1752 and an upper lip 1754 that run along
the length of lateral side 1730. Lateral side 1732 includes a
groove 1756 and an upper lip 1758 that run along the length of
lateral side 1732. Lower housing bottom 1704 has a flat bottom
surface 1772, a C-shaped groove 1774, two lozenge-shaped recesses
1776 and 1778, and an etched arrow 1780. Opposite ends 1782 and
1784 of C-shaped groove 1774 are separated by a gap 1786.
Lozenge-shaped recess 1776 includes a lip 1790 and an undercut 1792
at an outside end 1794 of lozenge-shaped recess 1776.
Lozenge-shaped recess 1778 includes a lip 1796 and an undercut 1798
at an outside end 1800 of recess 1778. Filter plate recess 1716 is
located within sled recess 1728 so that a filter plate (not shown)
mounted in filter plate recess 1716 will provide shielding to the
neutron-sensitive OSL sensor and the reference OSL sensor of a
dosimeter sled (not shown FIGS. 17, 18, 19, 20, 21, 22, 23 and 24)
slid into sled recess 1728.
[0245] FIGS. 25, 26, 27, 28, 29, 30, 31, 32 and 33 show a dosimeter
sled body 2502 according to one embodiment of the present
invention. FIGS. 25 and 27 show a sled body top face 2504 of
dosimeter sled body 2502. FIGS. 26 and 28 show a sled body bottom
face 2506 of dosimeter sled body 2502. Sled body top face 2504 and
sled body bottom face 2506 are opposite each other. Dosimeter sled
body 2502 includes three openings 2510, 2512 and 2514. Openings
2510, 2512 and 2514 include respective top portions 2518, 2520 and
2522 and respective bottom portions 2524, 2526 and 2528. Because
top portions 2518 and 2520 are smaller than respective bottom
portions 2524 and 2526 of openings 2510 and 2512, circular ledges
2540 and 2542 formed within openings 2510 and 2512 by top portions
2518 and 2520. Because top portion 2522 is smaller than bottom
portion 2528 of opening 2514, a circular ledge 2544 within openings
2514 is formed by top portion 2522. A round RFID tag (not shown)
may be mounted in a nearly circular recess 2556 in sled body top
face 2504. Dosimeter sled body 2502 has two parallel lateral sides
2562 and 2564, a curved end side 2566, a substantially straight end
side 2568, and two slanted corner sides 2570 and 2572. Lateral side
2562 includes a rail 2574 along the length of lateral side 2562 on
the bottom half of lateral side 2562. Rail 2574 protrudes from
lateral side 2562. Rail 2574 has beveled edges 2575. Lateral side
2564 includes a rail 2576 along the length of lateral side 2564 on
the bottom half of lateral side 2564. Rail 2576 protrudes from
lateral side 2564. Rail 2576 has beveled edges 2577. Lateral side
2562 includes a U-shaped detent 2578 and a tang 2579 near end side
2568. Rail 2574 includes three semicircular positioning notches
2580, 2582 and 2584. Sled body bottom face 2506 includes a bottom
face recess 2586. Bottom face recess 2586 includes indentations
2588, 2590, 2592, 2594 and 2596. Sled top face includes
alphanumeric indicia 2598. A FNTD (not shown) may be mounted in
bottom face recess 2586. Indentations 2588, 2590, 2592, 2594 and
2596 in the bottom face recess 2586 aid in mounting an FNTD in
bottom face recess 2586 and removing an FNTD from bottom face
recess 2586.
[0246] The beveled edges of the rails of the dosimeter sled provide
channels between the rails and the sled recess in the lower housing
to allow small amounts of dust and dirt to accumulate without
impeding the sled's traveling in and out of the sled recess.
[0247] FIGS. 34 and 35 show a dosimeter sled 3402 including
dosimeter sled body 2502. In dosimeter sled 3402, neutron-sensitive
OSL sensor 3410, reference OSL sensor 3412 and comparator OSL
sensor 3414 are mounted in respective openings 2510, 2512 and 2514
of dosimeter body 3502 and held in place by press fitting OSL
sensor 3410, reference OSL sensor 3412 and comparator OSL sensor
3414 into respective openings 2510, 2512 and 2514.
Neutron-sensitive OSL sensor 3410, reference OSL sensor 3412 and
comparator OSL sensor 3414 abut respective circular ledges 2540,
2542 and 2544. Neutron-sensitive OSL sensor 3410 is the OSL sensor
closest to curved end side 2566
[0248] Because OSL sensor 3410 is near curved end side 2566, curved
end side 2566 is curved to expand a region 3416 between OSL sensor
3410 and end side 2566, in comparison to the narrower region 673
between neutron-sensitive OSL sensor 626 and straight end side 666
of dosimeter sled 600, to ensure that the circular optical light
pipe of the OSL reader (not shown in FIGS. 34 and 35) is fully
covered when neutron-sensitive OSL sensor 3410 is read by the OSL
reader. There is enough distance between end side 2568 and OSL
sensor 3414 to cover the optical light pipe of the OSL reader, so
it is not as important to make end side 2568 curved.
[0249] Neutron-sensitive OSL sensor 3410 includes a disc-shaped
pellet of OSLM 3422, a converter material disc 3424, a cylindrical
cup-shaped inner filter 3426 and a cylindrical cup-shaped outer
filter 3428. OSLM 3422 and converter material disc 3424 are held in
place in inner filter 3426 by a retaining ring 3430. Converter
material disc 3424 is sandwiched between OSLM 3422 and inner filter
3426. Retaining ring 3430 is a spring-type retaining ring and is
held in place in inner filter 3426 by compression. Compressed in
inner filter 3426, ends 3432 and 3434 of retaining ring 3430 abut
each other. Inner filter 3426 is mounted and held in outer filter
3428 by press fitting inner filter 3426 into outer filter 3428.
OSLM 3422 has a filtered side 3436, the side of OSLM 3422 filtered
by converter material disc 3424, inner filter 3426 and outer filter
3428. Neutron-sensitive OSL sensor 3410 has an exposed side 3438
that allows the combined dosage of x-ray, gamma and neutron
radiation to which OSLM 3422 has been exposed to be read by an OSL
reader. Retaining ring 3430 is mounted on exposed side 3438 of OSLM
3422.
[0250] Reference OSL sensor 3412 includes a disc-shaped pellet of
OSLM 3442, a reference filter material disc 3444, a cylindrical
cup-shaped inner filter 3446 and a cylindrical cup-shaped outer
filter 3448. OSLM 3442 and reference filter material disc 3444 are
held in place in inner filter 3446 by a retaining ring 3450.
Reference filter material disc 3444 is sandwiched between OSLM 3442
and inner filter 3446. Retaining ring 3450 is a spring-type
retaining ring and is held in place in inner filter 3446 by
compression. Compressed in inner filter 3446, ends 3452 and 3454 of
retaining ring 3450 abut each other. Inner filter 3446 is mounted
and held in outer filter 3448 by press fitting inner filter 3446
into outer filter 3448. OSLM 3442 has a filtered side 3456, the
side of OSLM 3442 filtered by reference filter material disc 3444,
inner filter 3446 and outer filter 3448. Reference OSL sensor 3412
has an exposed side 3458 that allows the combined dosage of x-ray
and gamma radiation to which OSLM 3442 has been exposed to be read
by an OSL reader. Retaining ring 3450 is mounted on exposed side
3458 of OSLM 3442.
[0251] Comparator OSL sensor 3414 includes a disc-shaped pellet of
OSLM 3462, a reference filter material disc 3464 and, a cylindrical
cup-shaped filter 3466. OSLM 3462 and reference filter material
disc 3464 are held in place in filter 3466 by a retaining ring
3468. Reference filter material disc 3464 is sandwiched between
OSLM 3462 and filter 3466. Retaining ring 3468 is a spring-type
retaining ring and is held in place in filter 3466 by compression.
Compressed in inner filter 3466, ends 3470 and 3472 of retaining
ring 3468 abut each other. OSLM 3462 has a filtered side 3474, the
side of OSLM 3462 filtered by reference filter material disc 3464
and filter 3466. Comparator OSL sensor 3414 has an exposed side
3478, which allows the combined dosage of x-ray and gamma radiation
to which OSLM 3462 has been exposed to be read by an OSL reader.
Retaining ring 3468 is mounted on exposed side 3478 of OSLM
3462.
[0252] Neutron-sensitive OSL sensor 3410 is identical to reference
OSL sensor 3412, except for the substitution of reference filter
material disc 3444 of reference OSL sensor 3412 for converter
material disc 3424 in neutron-sensitive OSL sensor 3410. Comparator
OSL sensor 3414 is identical to reference OSL sensor 3412, except
filter 3466 is not mounted in an outer filter. In comparator OSL
sensor 3414, filter 3466 functions as an outer filter.
[0253] In the dosimeter sled of FIG. 34, the OSLM of one of the OSL
sensors has a converter material coated on the filtered side of the
OSLM allowing the OSLM to function as an OSL sensor that senses
gamma radiation and neutron radiation. The OSLM of a second OSL
sensor has a filter reference material coated on the filtered side
of the OSL that allows the OSLM to function as an OSL sensor for
gamma radiation.
[0254] In one embodiment of the present invention, when dosimeter
sled 3402 is positioned under an OSL reader (not shown in FIGS. 34
and 35), positioning notches 2584, 2582 and 2580 may be used to
properly position, in turn, OSL sensors 3414, 3412 and 3410
relative to an optical light pipe of a photo-optical engine (not
shown in FIGS. 34 and 35) the OSL reader. Positioning notch 2580
may be used to properly position neutron-sensitive OSL sensor 3410
over the optical light pipe of the OSL reader. Positioning notch
2582 may be used to properly position reference OSL sensor 3412
over the optical light pipe of the OSL reader. Positioning notch
2584 may be used to properly position comparator OSL sensor 3414
over the optical light pipe of the OSL reader.
[0255] Dosimeter sled 3402 may be slid into and out of sled recess
1728 of lower housing 1700 in a fashion similar to the way that
dosimeter sled 600 slides into and out of sled recess 412 of lower
housing 106. Rail 2574 of dosimeter sled 3402 slides in groove 1752
beneath upper lip 1754 of lower housing 1700. Rail 2576 of
dosimeter sled 3402 slides in groove 1756 beneath upper lip 1758 of
lower housing 1700. When fully slid into dosimeter sled 3402,
curved end side 2566 abuts curved wall portion of lower housing
1700. Etched arrow 1780 of lower housing 1700 indicates the
direction that a dosimeter sled 3402 may be slid out of lower
housing 1700.
[0256] When dosimeter sled 3402 is slid into lower housing 1700, a
thin rectangular energy compensating filter (not shown in FIG. 34)
mounted in filter plate recess 1716 shields neutron-sensitive OSL
sensor 3410 and reference OSL sensor 3412 from radiation, similar
to the way that copper filter discs 472 and 474 shield
neutron-sensitive OSL sensor 3410 and reference OSL sensor 3412,
respectively. In one embodiment, the thin rectangular energy
compensating filter may be molded into filter plate recess 1716. In
one embodiment, the thin rectangular energy compensating filter may
be made of copper.
[0257] Lower housing 1700, with dosimeter sled 3402 fully
slid/mounted therein, may be mounted in upper housing 104 by
screwing lower housing 106 into upper housing 1200 using screw
threads 1256 of upper housing 1200 and screw threads 1712 of lower
housing 1700. Lower housing 1700 may mounted in upper housing 1200,
when line A-A, associated with upper housing 1200, in FIG. 14 is
parallel to line B-B, associated with lower housing 1700, of FIG.
19. Upper housing 1200 may be released from lower housing 1700 by
grasping loops 1212 and 1214 and turning upper housing 90.degree.
counterclockwise, so that A-A is perpendicular to line B-B in which
upper housing 1200 is in a released position relative to lower
housing 1700.
[0258] FIG. 36 shows an upper housing top 3602 of an upper housing
3604 of a radiation dosimeter according to one embodiment of the
present invention. Upper housing 3604 includes a circular body 3606
and two generally trapezoidal-shaped loops 3612 and 3614 located on
respective opposite sides 3616 and 3618 of circular body 3606.
Loops 3612 and 3614 have respective openings 3626 and 3628 through
which a strap member (not shown) may be threaded so that the
dosimeter may be worn on the wrist of an individual. Upper housing
top 3602 has a contoured portion 3630, a flat pentagonal upper
surface 3632 and five (5) faceted regions 3634. Upper surface 3632
includes a curved arrow 3642, and a circular alignment symbol 3644.
A label with alphanumeric identification indicia (not shown) may be
adhered to upper housing top 3602 or alpha-number identification
indicia may be etched into upper housing top 3602. Upper housing
3604 includes a circular interior wall (not shown) including
interior screw threads (not shown). Upper housing 3604 may be used
with a lower housing of the present invention in a fashion similar
to the way that upper housing 104 may be used with lower housing
106 or upper housing 1200 may be used with lower housing 1700.
[0259] FIG. 37 shows an upper housing top 3702 of an upper housing
3704 of a radiation dosimeter according to one embodiment of the
present invention. Upper housing 3704 includes a circular body 3706
and two generally trapezoidal-shaped loops 3712 and 3714 located on
respective opposite sides 3716 and 3718 of circular body 3706.
Loops 3712 and 3714 have respective openings 3726 and 3728 through
which a strap member (not shown) may be threaded so that the
dosimeter may be worn on the wrist of an individual. Upper housing
top 3702 has a contoured portion 3730, a flat octagonal upper
surface 3732 and eight (8) faceted regions 3734. Upper surface 3732
includes a curved arrow 3742, and a circular alignment symbol 3744.
A label with alphanumeric identification indicia (not shown) may be
adhered to upper housing top 3702 or alpha-number identification
indicia may be etched into upper housing top 3702. Upper housing
3704 includes a circular interior wall (not shown) including
interior screw threads (not shown). Upper housing 3704 may be used
with a lower housing of the present invention in a fashion similar
to the way that upper housing 104 may be used with lower housing
106 or upper housing 1200 may be used with lower housing 1700.
[0260] FIG. 38 shows a radiation dosimeter 3802 according to one
embodiment of the present invention. Radiation dosimeter 3802
includes an upper housing 3804, a lower housing 3806 and a
dosimeter sled 3808 that slides into and out of lower housing 3806.
Upper housing 3804 includes two loops 3812 each having an opening
3814. Upper housing 3804 includes interior screw thread 3816. Lower
housing 3806 includes an external screw thread 3818 and a sled
recess (not visible in FIG. 38). A rectangular copper filter plate
3820 is mounted in a rectangular plate recess (not shown) of lower
housing 3806. A neutron-sensitive OSL sensor 3822 is mounted in an
opening 3824 of dosimeter sled 3808. A reference OSL sensor 3826 is
mounted in an opening 3828 of dosimeter sled 3808. A comparator OSL
sensor 3830 for reference OSL sensor 3826 is mounted in an opening
3832 of dosimeter sled 3808. A fluorescent nuclear track detector
(FNTD) 3842 is mounted in a bottom face recess 3844 of a bottom
face 3846 of dosimeter sled 3808. Dosimeter sled 3808 includes a
rail 3848. A bottom face 3850 of lower housing 3806 includes two
lozenge-shaped recesses 3852 and a C-shaped recess 3854.
[0261] Neutron-sensitive OSL sensor 3822 comprises a cylindrical
cup-shaped outer filter 3856, a cylindrical cup-shaped inner filter
3858, a converter material disc 3860, a conformal disc 3862, an
OSLM disc 3864 and a retaining ring 3866. Retaining ring 3866 holds
OSLM disc 3864, conformal disc 3862 and converter material disc
3860 in inner filter 3858. Inner filter 3858 is mounted in outer
filter 3856. Outer filter 3856 is mounted in opening 3822.
[0262] Reference OSL sensor 3826 comprises a cylindrical cup-shaped
outer filter 3870, a cylindrical cup-shaped inner filter 3872, a
reference filter material disc 3874, an OSLM disc 3878 and a
retaining ring 3880. Retaining ring 3880 holds OSLM disc 3878 and
reference filter material disc 3874 in inner filter 3872. Inner
filter 3872 is mounted in outer filter 3870. Outer filter 3870 is
mounted in opening 3826.
[0263] Comparator OSL sensor 3830 comprises a cylindrical
cup-shaped filter 3882, a reference filter material disc 3884, an
OSLM disc 3886 and a retaining ring 3888. Retaining ring 3888 holds
OSLM disc 3886 and reference filter material disc 3884 in filter
3882. Filter 3882 is mounted in opening 3830.
[0264] Although the OSLM discs shown in FIG. 38 are colored yellow
for illustration purposes, the OSLM discs are actually whitish in
color.
[0265] Conformal disc 3862, which is made of PE, is thinner and
more pliable than the thicker converter material disc 3860, which
is made of HDPE. In one embodiment of the present invention,
converter material disc 3860 may be made by punching out converter
material disc 3860 from a piece of HDPE material, which may lead to
converter material disc 3860 having a concave or convex shape. When
converter material disc 3860 has such a concave or convex shape, a
small gap is formed between converter material disc 3860 and OSLM
3864. Conformal disc 3862 may be used to fill this gap. The
combination of conformal disc 3862 and converter material disc 3860
may be viewed as functioning as a "composite converter material
disc". Conformal disc 3862 ensures that there is more intimate
contact between this "composite converter material disc" and OSLM
3864. Outer filters 3856 and 3870 are made of copper. Inner filters
3858 and 3872 and filter 3882 are made of aluminum. OSLM discs
3864, 3878 and 3886 are made of an Al.sub.2O.sub.3:C material.
Retaining rings 3866, 3880 and 3888 are made of stainless
steel.
[0266] FIG. 39 shows a sled body bottom face 3902 of a dosimeter
sled body 3904 of dosimeter sled 3808. Dosimeter sled body 3904 is
similar to dosimeter sled body 602. Openings 3824, 3828 and 3832
include respective top portions (not shown) and respective bottom
portions 3924, 3926 and 3928. Because the top portions are smaller
than respective bottom portions 3924, 3926 and 3928 of openings
3824, 3828 and 3832, neutron-sensitive OSL sensor 3822, reference
OSL sensor 3826 and comparator OSL sensor 3830 mounted in openings
3824, 3828 and 3832 abut respective circular ledges 3940, 3942 and
3944 formed within openings 3824 and 3828 by the top portions of
these openings. A round RFID tag (not shown) may be mounted on the
top (not shown) of dosimeter sled body 3904. Dosimeter sled body
3904 has two parallel lateral sides 3962 and 3964, two
substantially straight end sides 3966 and 3968, and two slanted
corner sides 3970 and 3972. Lateral side 3962 includes a rail 3848
along the length of lateral side 3962 on the bottom half of lateral
side 3962. Rail 3848 protrudes from lateral side 3962. Lateral side
3964 includes a rail 3976 along the length of lateral side 3964 on
the bottom half of lateral side 3964. Rail 3976 protrudes from
lateral side 3964. Lateral side 3962 includes a U-shaped detent
3978 and a tang 3979 near end side 3968. Rail 3848 includes three
semicircular positioning notches 3980, 3982 and 3984. Sled body
bottom face 3902 includes a bottom face recess 3844. Bottom face
recess 3844 includes indentations 3988, 3990, 3992, 3994 and 3996.
Indentations 3988, 3990, 3992, 3994 and 3996 in bottom face recess
3844 aid in mounting FNTD 3842 in bottom face recess 3844 and in
removing FNTD 3842 from the bottom face recess 3844.
[0267] A sled top face (not shown) of sled 3808 may include
alphanumeric indicia (not shown).
[0268] FIG. 40 shows dosimeter sled 3808 with FNTD 3842 mounted in
bottom face recess 3844. As can be seen in FIG. 40, FNTD 3842 is
punch card-shaped.
[0269] In the dosimeter sled of FIGS. 38, 39 and 40, the recess is
constructed so that one part of the FNTD is in contact with the
sled. Examples of suitable fluorescent nuclear track detectors are
described in U.S. patent application Ser. No. 12/258,035 to
Akselrod, et al., entitled "METHOD OF LUMINESCENT SOLID STATE
DOSIMETRY OF MIXED RADIATIONS" filed Oct. 24, 2008, the entire
contents and disclosure of which are incorporated herein by
reference. The recess also has facets where a PTFE reference filter
is placed and a LiF or other Li based compound is placed. That is,
there are three, adjacent filtered areas over the single FNTD
sensor. When the dosimeter sled is made of HDPE, that area senses
neutrons in the form of recoil protons and gamma rays/x-rays. The
area filtered by the PTFE senses only gamma rays/x-rays. The Li
filtered area senses neutrons using an alternative neutron
interaction process whereby the lithium captures the neutron and
splits into an alpha particle and a tritium or H-3 ion. The alpha
particle and tritium ion as well as the recoil proton from the HDPE
create tracks in the FNTD that once counted or otherwise quantified
can be related to the neutron dose. The FNTD is more sensitive than
the OSLM to neutrons but not to gamma rays and x-rays. The FNTD may
be used as a back-up or secondary dosimeter, because its signal is
more robust. However, because the FNTD cannot be read in a compact
portable reader, the FNTD may be removed from the sled and read in
a special reader at another location, such as a laboratory.
[0270] FIGS. 41, 42, 43, 44 and 45 show a dosimeter upper housing
4100 of a radiation dosimeter according to one embodiment of the
present invention. FIGS. 41 and 43 show upper housing top 4102.
FIGS. 42 and 44 show upper housing bottom 4104. Dosimeter upper
housing 4100 includes a circular body 4106 and two generally
trapezoidal-shaped loops 4112 and 4114 located on respective
opposite sides 4116 and 4118 of circular body 4106. Loops 4112 and
4114 have respective openings 4126 and 4128 through which a strap
member (not shown) may be threaded so that the dosimeter may be
worn on the wrist of an individual. Upper housing top 4102 has a
circular contoured portion 4130 and a flat circular upper surface
4132 and includes a curved arrow 4142, a circular alignment symbol
4144 and a shallow rounded rectangular recess 4146. In one
embodiment of the present invention, a label with alphanumeric
identification indicia (not shown) may be adhered to upper housing
top 4102 in a shallow rounded rectangular recess 4146. In another
embodiment of the present invention, alphanumeric identification
indicia (not shown) may be engraved in shallow rounded rectangular
recess 4146. Circular interior wall 4154 of upper housing bottom
4104 includes interior screw threads 4156, a circumferential gasket
4158 and a protrusion 4160. Interior wall 4154 surrounds a circular
recess 4162 with a flat bottom 4164.
[0271] The gasket may be made of a suitable gasket materials such
as rubber, silicone, etc.
[0272] In one embodiment of the present invention, in addition to
screw threads, the lower housing and/or upper housing has a raised
surface consisting of a gasket material, such as silicone or
rubber, so that the two housings when screwed together provide a
water-tight seal.
[0273] FIGS. 46, 47, 48, 49, 50, 51, 52, 53, 54 and 55 show a
dosimeter sled body 4602 according to one embodiment of the present
invention. FIGS. 46 and 48 show a sled body top face 4604 of
dosimeter sled body 4602. FIGS. 47 and 49 show a sled body bottom
face 4606 of dosimeter sled body 4602. Sled top face 4604 and sled
body bottom face 4606 are opposite each other. Dosimeter sled body
4602 includes three openings 4610, 4612 and 4614. Openings 4610,
4612 and 4614 include respective top portions 4618, 4620 and 4622
and respective bottom portions 4624, 4626 and 4628. Because top
portions 4618 and 4620 are smaller than respective bottom portions
4624 and 4626 of openings 4610 and 4612, circular ledges 4640 and
4642 are formed within openings 4610 and 4612 by top portions 4618
and 4620. Because top portion 4622 is smaller than bottom portion
4628 of opening 4614, a circular ledge 4644 within openings 4614 is
formed by top portion 4622. A round RFID tag (not shown, similar to
RFID tag 660) may be mounted in an RFID tag recess 4656 in sled
body top face 4604. RFID tag recess 4656 includes a flat outer
portion 4657 for receiving a flat circumferential part of an RFID
tag including an antenna (not shown) and a curved inner portion
4658 for receiving a protruding memory chip of the RFID tag. RFID
tag recess 4656 also includes indentations 4659 and 4560 for
receiving respective adhesive dots used in mounting the RFID tag in
RFID tag recess 4656. Dosimeter sled body 4602 has two parallel
lateral sides 4662 and 4664, a curved end side 4666, a
substantially straight end side 4668, and two slanted corner sides
4670 and 4672. Lateral side 4662 includes a rail 4674 along the
length of lateral side 4662 on the bottom half of lateral side
4662. Rail 4674 protrudes from lateral side 4662. Rail 4674 has
beveled edges 4675. Lateral side 4664 includes a rail 4676 along
the length of lateral side 4664 on the bottom half of lateral side
4664. Rail 4676 protrudes from lateral side 4664. Rail 4674 has
beveled edges 4677. Lateral side 4662 includes a U-shaped detent
4678 and a tang 4679 near end side 4668. Rail 4674 includes three
semicircular positioning notches 4680, 4682 and 4684. Sled body
bottom face 4606 includes a bottom face recess 4686. Bottom face
recess 4686 includes indentations 4688, 4690, 4692, 4694 and
4696.
[0274] A FNTD (not shown) may be mounted in bottom face recess 4686
in and a FNTD holder 4702 that includes a raised bed 4704 and a
spring flange 4706. Bottom face recess 4686 also includes a
retaining lip 4708. Spring flange 4706 and retaining lip 4708 are
used to retain an FNTD in FNTD holder 4702. Spring flange 4706 may
be pushed outwardly to allow the FNTD to be placed in FNTD holder
4702. Spring flange 4706 then springs back to force the FNTD
against a wall 4710 of bottom face recess 4686 below retaining lip
4708. Indentations 4688, 4690, 4692, 4694 and 4696 in the bottom
face recess of the sled body aid in mounting an FNTD in bottom face
recess 4686 and in removing an FNTD from bottom face recess 4686.
Sled top face 4604 includes alphanumeric indicia 4712.
[0275] The beveled edges of the rails of the dosimeter sled provide
channels between the rails and the sled recess in the lower housing
to allow small amounts of dust and dirt to accumulate without
impeding the sled's traveling into and out of the sled recess.
[0276] Because an OSL sensor mounted in opening 4610 would be the
closest OSL sensor to curved end side 4666, curved end side 4666 is
curved to expand a region 4714 between opening 4610 and curved end
side 4666, in comparison to the narrower region 673 between
neutron-sensitive OSL sensor 626 and straight end side 666 of
dosimeter sled 600, to ensure that the circular optical light pipe
of the OSL reader (not shown in FIGS. 34 and 35) is fully covered
when the OSL sensor mounted in opening 4610 is read by the OSL
reader. There is enough distance between end side 4668 and opening
4614 to cover the optical light pipe of the OSL reader, so it is
not as important to make end side 4668 curved.
[0277] For the FNTD, there are three (3) filter materials. In the
embodiment of the present invention shown in FIGS. 46, 47, 48, 49,
50, 51, 52, 53, 54 and 55, one filter material is the raised bed of
the FNTD holder that is part of the dosimeter sled made of HDPE
and, therefore, acts as neutron converter. A second filter material
is made of PTFE and is placed in the bottom face recess and acts as
a reference filter material. A third filter material is a lithium
fluoride crystal that converts low energy neutrons into recoil
alpha particles and tritium particles.
[0278] FIG. 55 shows a dosimeter lower housing 5502 screwed into
dosimeter upper housing 4100. Lower housing 4402 is similar to
lower housing 1700. Exterior screw threads 5512 of lower housing
5502 engage interior screw threads 4156 of upper housing 4100.
Gasket 4158 provides a seal between a sealing shelf 5522 of upper
housing 4100 and a sealing shelf 5524 of lower housing 5502.
Dosimeter sled body 4602 is shown slid into lower housing 5502 with
an RFID tag 5514 mounted in RFID tag recess 4656. FIG. 57 shows
greater detail of how gasket 4158 provides a seal between a sealing
shelf 5522 of upper housing 4100 and a sealing shelf 5524 of lower
housing 5502. As shown in FIG. 57, gasket 4158 is circumferentially
mounted in a circular groove 5702 in sealing shelf 5522.
[0279] FIGS. 58, 59, 60, 61, 62 and 63 show an OSL sensor 5802 and
the component parts of OSL sensor 5802 according to one embodiment
of the present invention. OSL sensor 5802 includes a disc-shaped
pellet of OSLM 5810, a filter material disc 5812, a cylindrical
cup-shaped inner filter 5814 and a cylindrical cup-shaped outer
filter 5816. OSLM 5810 and filter material disc 5812 are held in
place in inner filter 5814 by a retaining ring 5818. Filter
material disc 5812 is sandwiched between OSLM 5810 and inner filter
5814. Retaining ring 5818 is a spring-type retaining ring and is
held in place in inner filter 5814 by compression. Compressed in
inner filter 5814, ends 5820 and 5822 of retaining ring 5818 abut
each other. Inner filter 5814 is mounted and held in outer filter
5816 by press fitting inner filter 5814 into outer filter 5816.
OSLM 5810 has a filtered side 5836, the side of OSLM 5810 filtered
by filter material disc 5812, inner filter 5814 and outer filter
5816. OSLM 5810 has an exposed side 5840. Retaining ring 5818 is
mounted on exposed side 5840 of OSLM 5810.
[0280] OSL sensor 5802 has a width/diameter 5842 and a height 5844.
OSLM 5810 has a width/diameter 5852 and a height 5854.
[0281] For the OSL sensor of FIGS. 58 and 59, if the outer filter
is made of copper, the inner filter is made of aluminum, the OSLM
comprises an Al.sub.2O.sub.3:C material and the filter material
disc is made of high-density polyethylene, then the OSL sensor
corresponds to neutron-sensitive OSL sensor 626 of FIGS. 6 and 7.
In FIGS. 58 and 59, if the outer filter is made of copper, the
inner filter is made of aluminum, the OSLM comprises an
Al.sub.2O.sub.3:C material and the filter material disc is made of
polytetrafluoroethylene, then the OSL sensor corresponds to
reference OSL sensor 628 of FIGS. 6 and 7.
[0282] For the OSL of FIGS. 58 and 59, if the filter material disc
is made of a converter material, then the OSL sensor corresponds to
neutron-sensitive OSL sensor 3410 of FIGS. 34 and 35. In FIGS. 58
and 59, if the filter material disc is made of a reference filter
material, then the OSL sensor corresponds to reference OSL sensor
3412 of FIGS. 34 and 35.
[0283] In one embodiment of the present invention, the OSL sensor
has a width/diameter of about 7.7 mm to about 7.8 mm. In one
embodiment, the OSL sensor has a width/diameter of about 6.8 mm to
about 6.9 mm.
[0284] In one embodiment of the present invention, the OSLM has a
height of about 0.135 mm to about 0.145 mm.
[0285] In one embodiment of the present invention, the OSLM has a
width/diameter of about 5.9 mm to about 6 mm.
[0286] In one embodiment of the present invention, the OSLM has a
height of about 0.135 mm to about 0.145 mm.
[0287] FIGS. 60 and 61 show OSLM 5810 mounted in inner filter 5814.
Inner filter 5814 includes a circular base 6012 having a
cylindrical wall 6014 extending therefrom forming a recess 6016 in
which OSLM 5810 is mounted. Inner filter 5814 has a width/diameter
6022 and a height 6024. Circular base 6012 has a thickness 6026.
Cylindrical wall 6014 has a thickness 6028. Recess 6016 has a
width/diameter 6032 that is the same as width/diameter 5852 of OSLM
5810.
[0288] In one embodiment of the present invention, the inner filter
has a width/diameter of about 6.8 mm to about 6.9 mm. In one
embodiment of the present invention, the inner filter has a height
of about 2.4 mm to about 2.5 mm. In one embodiment of the present
invention, the base of the inner filter has a thickness of about
0.2 mm to about 2.1 mm. In one embodiment of the present invention,
the cylindrical wall of the inner filter has a width of about 0.2
mm to about 0.21 mm. In one embodiment of the present invention,
the recess of the inner filter has a minimum width/diameter of
about 6.1 mm to about 6.2 mm.
[0289] FIGS. 62 and 63 shows retaining ring 5818 in a relaxed state
having a gap 6212 between ends 5820 and 5822. Retaining ring 5818
has a maximum diameter of 6214, a x-thickness 6216 and a
y-thickness 6218. Maximum diameter 6214 is slightly greater than
the width/diameter 6032 of recess 6016 of inner filter 5814.
[0290] In one embodiment of the present invention, the retaining
ring has an x-thickness of about 0.6 mm to about 0.62 mm. In one
embodiment of the present invention, the retaining ring has an
y-thickness of about 0.6 mm to about 0.62 mm.
[0291] FIGS. 64 and 65 show outer filter 5816. Outer filter 5816
includes a circular base 6412 having a cylindrical wall 6414
extending therefrom forming a recess 6416. Outer filter 5816 has a
width/diameter 6422 and a height 6424. Circular base 6412 has a
thickness 6426. Cylindrical wall 6414 has a thickness 6428. Recess
6416 has a width/diameter 6432 that is substantially the same as
the width/diameter 6222 of inner filter 5814.
[0292] In one embodiment of the present invention, the outer filter
has a width/diameter of about 7.7 mm to about 7.75 mm. In one
embodiment of the present invention, the outer filter has a height
of about 3 mm to about 3.1 mm. In one embodiment of the present
invention, the base of the outer filter has a thickness of about
0.36 mm to about 0.37 mm. In one embodiment of the present
invention, the cylindrical wall of the outer filter has a width of
about 0.4 mm to about 0.41 mm.
[0293] Although cylindrical cup-shaped filters used in the
embodiments of the OSL sensors of the present invention are
described above and shown in the drawings, the filters of the
present invention may be any of a variety of shapes. An advantage
of cylindrical cup-shaped radiation filters is that they are able
to measure a high angle of incidence of radiation. Instead of
having a circular base, the filters of the present invention may
have bases of other shapes such as oval, triangular, square,
rectangular, pentagonal, hexagonal, octagonal, etc. A filter of the
present invention may be solid, in which case the filter is mounted
above one side of the OSLM or mounted on the OSL. Or, similar to
the OSL sensor of FIGS. 58 and 59, the filters may have a recess in
which the OSLM may be mounted. The cross-sectional shape of the
recess may be similar to the shape of the base, such as the
circular cross-sectional shape of the recesses of FIGS. 58, 59, 60,
61, 62 and 63.
[0294] An OSL sensor of the present invention may include one, two,
three or any other number of filters. When the filters are
cup-shaped, the filters may nest, one within each other, as shown
in FIGS. 7, 34, 35, 58, 59, 60 and 61. Although cup-shaped filters
having circular cross-sections are shown in FIGS. 7, 34, 35, 58,
59, 60, 61, 62 and 63, cup-shaped filters having other
cross-sectional shapes such as oval, triangular, square,
rectangular, pentagonal, hexagonal, octagonal, etc. may also be
nested in each other.
[0295] In one embodiment of the present invention, an OSL sensor
may use only one cylindrical cup-shaped filter for the
neutron-sensitive OSL sensor and the reference OSL sensor as long
as both OSL sensors respond similarly to gamma radiation and x-ray
radiation.
[0296] Although disc-shaped pellets of OSLM used in the embodiments
of the OSL sensors of the present invention are described above and
shown in the drawings, the OSLM used in the OSL sensors may have a
variety of shapes and cross-sections. When mounted in a filter, the
OSLM may have a shape that is complementary to the shape of the
filter, such as a disc-shaped pellet of OSLM mounted in a
cylindrical cup-shaped filter or a cube or rectangular box-shaped
pellet of OSLM mounted in a filter with a rectangular box-shaped
recess.
[0297] In one embodiment of the present invention, the OSLM may be
poured into a cup-shaped filter in a liquid form. When the OSLM
solidifies, the OSLM takes on the shape of the recess in the
cup-shaped filter.
[0298] In one embodiment, the OSLM of the present invention may be
a disc-shaped pellet comprising Al.sub.2O.sub.3:C made from
particles having a grain size of 30-40 .mu.m. The thickness of the
pellet may vary depending on the particular application.
[0299] Although the filters of the present invention in the
embodiments described above and shown in the drawing figures are
made of copper and aluminum, the filters of the present invention
may be made of other materials that are sensitive to radiation. In
one embodiment, the filters may be made of plastic having dispersed
therein metal particles or a metal powder. The type of metal used
in such a plastic/metal filter and the size of the particles may
vary depending on the function of the filter. For example, metals
having a large atomic weight may be desirable if the filter is used
to remove the presence of low energy x-rays. The degree of x-ray
absorption can be adjusted by changing the concentration and grain
size of the metal particles in the plastic/metal filter. Metals
having smaller atomic weights may be used in filters designed to
provide less energy compensation. The degree of x-ray absorption
can be adjusted by changing the concentration and grain size of the
metal particles in the plastic/metal filter.
[0300] In one embodiment of the present invention the filters
carried by a dosimeter sled may include plastic/metal filters each
having different types of metal particles and/or having different
concentrations of metal particles and/or having metal particles of
different grain sizes dispersed in the plastic material of each
filter.
[0301] Although in the embodiments shown there are three OSL
sensors in the dosimeter sled, in some embodiments of the present
invention there may be one, two, or four or more OSL sensors in the
dosimeter sled. If necessary, four or more sensors may be
accommodated in the dosimeter sled by making each of the OSL
sensors smaller or making the dosimeter sled longer, thicker or
wider.
[0302] If necessary, additional sensors and additional types of
radiation sensors may be accommodated in the dosimeter sled by
making each of the OSL sensors smaller or making the dosimeter sled
longer, thicker or wider.
[0303] In one embodiment of the present invention, a converter
material disc has a thickness of 1 mm to about 1.1 mm. In one
embodiment of the present invention, the converter material may be
a film or sheet having a thickness of 0.1 mm to about 0.2 mm. In
one embodiment the converter material may be a film of polyethylene
having a thickness of less than 1 mm.
[0304] In one embodiment the present invention, a reference filter
material coating has a thickness of 1 mm to about 1.1 mm. In one
embodiment of the present invention, the reference filter material
may be a film or sheet having a thickness of 0.1 mm to about 0.2
mm. In one embodiment of the present invention, the reference
filter material may be a film of polytetrafluorethylene having a
thickness of less than 1 .mu.m.
[0305] In various embodiments of the present invention, including
the embodiments shown above and described in the drawings, the
radiation dosimeter may include an RFID tag that identifies the
radiation dosimeter and the individual associated with the
radiation dosimeter i.e. the individual who has been wearing the
radiation dosimeter. The identification information from the RFID
tag allows an RFID tag reader that is part of a dosimeter reader to
access information about the radiation dosimeter and the individual
from a database. Such information may include: the identity of the
individual who has been wearing the radiation dosimeter, the last
time the radiation dosimeter was read, the serial number of the
reader used for the last dosage measurement, a record of the
results of previous readings of the dosimeter, a record of the
individual's cumulative exposure to various types of radiation, an
alphanumeric serial number assigned to the dosimeter, an
alphanumeric serial number assigned to the upper housing, an
alphanumeric serial number assigned to the lower housing, an
alphanumeric serial number assigned to the dosimeter sled, etc. In
some embodiments, the dosimeter reader may also transmit
information to the database to update the information for the
radiation dosimeter and the individual in the database. The
database may be stored in the dosimeter reader or stored at another
location such as a personal computer, a networked computer, a
centralized record database, etc.
[0306] Although the identification indicia/alphanumeric serial
number assigned to the dosimeter sled and upper housing are
identical in the embodiments described above and shown in the
drawings, in other embodiments the dosimeter sled and lower housing
may be assigned different alphanumeric serial numbers. The
dosimeter as a whole and the upper housing may also be assigned
alphanumeric serial numbers that are the same as or different from
the serial numbers assigned to the lower housing and dosimeter
sled.
[0307] FIG. 66 shows a radiation dosimeter 6602 according to one
embodiment of the present invention including a strap member 6604
threaded through openings 6612 and 6614 of respective loops 6616
and 6618 of radiation dosimeter 6602. Strap member 6604 is threaded
beneath the lower housing (not shown) of radiation dosimeter 6602.
Strap member 6604 includes a buckle 6632 and loop 6634 through
which an end 6636 may be slipped so that radiation dosimeter 6602
may be worn on an individual's wrist, similar to the way that a
wristwatch is worn. Strap member 6604 may be easily removed from
radiation dosimeter 6602 to allow radiation dosimeter 6602 to be
read.
[0308] FIG. 67 shows a radiation dosimeter 6702 according to one
embodiment of the present invention including a strap member 6204
threaded through openings 6712 and 6714 of respective loops 6716
and 6718 of radiation dosimeter 6702. Strap member 6704 is threaded
above upper housing 6722 of radiation dosimeter 6702. Strap member
6704 includes a buckle 6732 through which an end 6734 may be
slipped so that radiation dosimeter 6702 may be worn on an
individual's wrist, similar to the way that a wristwatch is worn.
Strap member 6704 may be easily removed from radiation dosimeter
6702 to allow radiation dosimeter 6702 to be read.
[0309] FIG. 68 shows a radiation dosimeter 6802 according to one
embodiment of the present invention that is attached to a clip
6804. Clip 6804 includes a strap member 6812 that is looped through
an opening 6820 of a loop 6822 of radiation dosimeter 6802. Strap
member 6812 is fastened back on itself by a snap fastener 6832.
Attached to strap member 6812 by a bolt 6834 is a spring clip 6836.
Spring clip 6836 may be used to clip radiation dosimeter 6802 to a
shirt or pants pocket, a shirt lapel, a necklace worn by an
individual, etc. Strap member 6812 may be easily removed from
radiation dosimeter 6802 to allow radiation dosimeter 6802 to be
read.
[0310] Although in the embodiment shown, the strap member is a
one-piece strap member, in other embodiments of the present
invention, the strap member may be a two-piece strap member.
[0311] Various types of strap members, both adjustable and
non-adjustable, may be used with the dosimeter of the present
invention. For example, the strap member may be a one-piece elastic
strap. The strap member may also be an adjustable strap where the
two ends of the strap are buckled together in a fashion similar to
the way that a belt is buckled around an individual's waist or a
wristwatch is buckled around an individual's wrist. In such a
configuration, one end of the strap member includes a buckle
through which the second end of the strap member is inserted. The
strap member may also be an adjustable strap member in which one
end of the strap member includes a buckle through which the second
end of the strap is threaded, thereby allowing the length of the
strap member to be adjusted by sliding the second strap through the
buckle, similar to the adjustable two-piece straps used in
backpacks, shoulder bags, fanny packs, etc. An example of such a
two-piece strap member is described in U.S. Pat. No. 5,632,429 to
Cantwell, the entire contents and disclosure of which are
incorporated herein by reference. The strap member may also be an
adjustable strap member whose ends are adjustably fastened together
using hook-and-loop fasteners (e.g. Velcro.RTM.) with a strip of
hooks on one end of the strap member and a strip of loops on the
other end of the strap member. Using hook-and-loop fasteners to
fasten the strap member together also allows the size of the strap
member to be adjusted by making the strip of hooks and/or the strip
of loops long enough that the strips may be fastened together to
form a strip member of various lengths. Various other types of
adjustable and non-adjustable strip members may also be used with
the dosimeter of the present invention.
[0312] The dosimeter of the present invention may be worn by an
individual in a variety of ways. For example, the dosimeter may be
worn on a strap around a user's wrist, arm, shoulder, head, waist,
ankle, leg, etc. The dosimeter may also be worn on a strap around
an article of the individual's clothing such as a helmet,
shirtsleeve, pants leg, etc. The dosimeter may also be carried in
an individual's shirt pocket, pants pocket, etc.
[0313] FIGS. 69, 70 and 71 show a portable dosimeter reader 6902
according to one embodiment of the present invention that comprises
a dosimeter reader body 6904 mounted in a clamshell type dosimeter
reader case 6906. Dosimeter reader body 6904 includes a dosimeter
reader chassis 6908, a dosimeter drawer 6910, a battery compartment
6912, a display 6920 and control buttons 6922, 6924 and 6926.
Control buttons 6922, 6924 and 6926 may be used by an individual
to: turn on and off the power for dosimeter reader 6902, initiate
an analytical sequence for dosimeter reader 6902, and turn on a
back light for display 6920 for viewing the results in low light.
Control buttons 6922, 6924 and 6926 may also be used cycle through
various screen displays on display 6920 of: dose results, raw data,
calibration factors and other information used in analyzing the
results from reading a dosimeter (not shown in FIGS. 69, 70 and
71). Dosimeter reader body 6904 has three regions: a dosimeter
loading/unloading region 6932, a dosimeter ready region 6934 and a
dosimeter reading region 6936. A housing cover 6940 covers
dosimeter ready region 6934 and dosimeter reading region 6936.
Contained in battery compartment 6912 are four (4) AA batteries
(not visible in FIGS. 69, 70 and 71) that provide power for
dosimeter reader 6902. Dosimeter reader case 6906 has an upper
shell 6952 and an lower shell 6954 that are pivotably connected to
each other by pivot joints 6956 and 6958. Upper shell 6952 includes
latches 6960 and 6962 that engage latch receiving structures 6964
and 6966 on lower shell 6954 to hold upper shell 6952 and lower
shell 6954 together when upper shell 6952 is pivoted to cover lower
shell 6954. A handle 6968, which may be used to carry dosimeter
reader 6902, is pivotably mounted on lower shell 6954.
[0314] Pivot joint 6956 is comprised of upper pivot structures 6972
and 6974 of upper shell 6952, lower pivot structures 6976, 6978 and
6980 of lower shell 6954, and a pin (not visible in FIGS. 69, 70
and 71) that extends through pivot structures 6972, 6974, 6976,
6978 and 6980. Pivot joint 6958 is comprised of upper pivot
structures 6982 and 6984 of upper shell 6952, lower pivot
structures 6986, 6988 and 6980 of lower shell 6954, and a pin (not
visible in FIGS. 69, 69 and 70) that extends through pivot
structures 6982, 6984, 6986, 6988 and 6990. Upper shell 6952
includes operating instructions 6992 for dosimeter reader 6902.
Dosimeter reader body 6904 is mounted in a clamshell type dosimeter
reader case 6906 by screws 6994 being screwed through openings 6996
into threaded opening 6998 in a frame 7002 mounted in lower shell
6954.
[0315] Upper shell 6952 includes a peripheral groove 7012 around a
peripheral edge 7014 of upper shell 6952. Lower shell 6954 includes
a peripheral ridge 7022 around a peripheral edge 7024 of lower
shell 6954. When dosimeter reader case 6906 is closed, peripheral
ridge 7022 engages peripheral groove 7012 to form a seal that makes
dosimeter reader case 6906 air-tight and water-tight. Lower shell
includes a pressure relief valve 7032 that allows dosimeter reader
case 6906 to be easily opened when the atmospheric or altitudinal
pressure is different during opening than when the dosimeter reader
case 6906 is closed. If the pressure inside dosimeter reader case
6906 is much less that the outside pressure, dosimeter reader case
6906 may be hard to open.
[0316] FIGS. 72, 73, 74 and 75 show details of dosimeter drawer
6910 and dosimeter loading/unloading region 6932. Dosimeter drawer
6910 includes a drawer base 7202 (a dosimeter receiving surface)
and a drawer handle 7204. Drawer handle 7204 is part of a hollow
drawer housing 7206. A top face 7208 of drawer base 7202 includes a
C-shaped ridge 7212. Two retaining tabs 7218 and 7220 extend
through respective openings 7222 and 7224 in drawer base 7202.
Retaining tab 7218 includes an exterior leg 7232 and interior leg
7234. Leg 7232 includes a foot 7236. Retaining tab 7220 includes an
exterior leg 7242 and interior leg 7244. Leg 7242 includes a foot
7246. An exposed kidney-shaped dosimeter loop retainer 7256 extends
through an opening 7258 in drawer base 7202. A covered
kidney-shaped dosimeter loop retainer 7260 extends through an
opening 7262 in drawer base 7202 and is covered by drawer housing
7206. Dosimeter loop retainer 7260 is slightly longer than
dosimeter loop retainer 7256. Dosimeter loop retainer 7256 includes
a receiving slot 7264, an end wall 7266, a base 7268 and a spring
tab 7270. Dosimeter loop retainer 7260 includes a receiving slot
7272, an end wall 7274, a base 7276 and a spring tab 7278. Drawer
housing 7206 includes an alignment dot 7282 at a curved edge 7284
of drawer housing 7206. Another alignment dot 7286 is located on
dosimeter reader chassis 6908 adjacent to drawer base 7202. Also
visible in FIGS. 72, 73 and 75 is an entrance 7292 into a ready
region housing 7294 covered by housing cover 6940. To one side of
entrance 7292 there is a piece of foam cushioning 7296. Drawer base
7202 also includes a loop stop 7298. Drawer base 7202 is slidably
mounted an opening 7402 in dosimeter reader chassis 6908. Opening
7402 is located between edges 7404 and 7406. A screw 7412 is used
to mount an axis mount (not visible in FIGS. 72, 73, 74 and 75) on
a bottom face (not visible in FIGS. 72, 73, 74 and 75) of drawer
base 7202. Exterior leg 7232 has an exterior leg top 7532, interior
leg 7234 has an interior leg top 7534, exterior leg 7242 has an
exterior leg top 7542 and interior leg 7344 has an interior leg top
7544.
[0317] In FIG. 76 housing cover 6940 is removed to show a reader
housing 7602 and RFID tag reader 7604 in dosimeter reading region
6936 that are usually covered by housing cover 6940. RFID tag
reader 7604 includes an RF antenna 7606. RF antenna 7606 may be
used to communicate with the RF antenna of an RFID tag of a
dosimeter sled (not shown) that is positioned below RFID tag reader
7604.
[0318] In FIG. 77 housing cover 6940 is removed to show ready
region housing 7702 and reader housing 7602 that are normally
covered by housing cover 6940. Ready region housing 7702 has three
walls 7704, 7706 and 7708. RFID tag reader 7604 is removed to show
OSL reader 7712. OSL reader 7712 includes a sled slider 7714 that
travels on rails 7716 and 7718 of slide rail base 7720. Sled slider
7714 is moved back and forth on rails 7716 and 7718 by drive
mechanism 7722. In FIG. 77 a distal end 7732 of drawer base 7202 is
at entrance 7292 of ready region housing 7294. Reader housing 7602
includes walls 7742, 7744, 7746 and 7708. Wall 7708 is shared with
ready region housing 7702.
[0319] FIG. 78 shows drive gear 7802, return wheel 7804 and toothed
belt 7806 of drive mechanism 7722. Toothed belt 7806 is driven by
drive gear 7802 and travels around drive gear 7802 and return wheel
7804. Sled slider 7714 is mounted on toothed belt 7806 by a
carriage 7812.
[0320] FIG. 79 shows a sled slider motor 7912 mounted on dosimeter
reader chassis 6908. Sled slider motor 7912 includes a rotating
drive shaft (not visible in FIG. 79) on which drive gear 7802 (not
visible in FIG. 79) is mounted. Sled slider motor 7912 drives drive
gear 7802 using the rotating drive shaft, thereby controlling the
motion of sled slider 7714 (not visible in FIG. 79). FIG. 79 also
shows PCB 8420 of OSL reader 7712 mounted underneath dosimeter
reader chassis 6908 using screw posts 7922 and screws 7924. Only
two screw posts 7922 and two screws 7924 are visible in FIG. 79,
but four screw posts 7922 and four screws 7924 are used to mount
PCB 8420 to dosimeter reader chassis 6908. PCB 8420 is spaced from
dosimeter reader chassis 6908 by screw posts 7922 to allow motor
7912 to be located between dosimeter reader chassis 6908 and PCB
8420. In addition, FIG. 79 shows a USB port 7942 in wall 7744 of
reader housing 7602. USB port 7942 allows dosimeter reader 6902 to
communicate with other electronic devices, such as a computer, a
data storage device, a printer, a monitor, etc. using a USB cable
(not shown) plugged into USB port 7942.
[0321] Although one way of moving the sled slider is described
above and show in the drawings, the motion of the sled slider may
be moved in other ways. For example, the sled slide may be moved
back and forth using a rack and pinion drive system in which a
rotatable pinion gear is mounted on the sled slider and the sled
slider is moved back and forth by rotating the pinion gear along a
toothed rack.
[0322] FIGS. 80 and 81 show additional details of OSL reader 7712.
Visible in FIGS. 80 and 81 is an optical light pipe 8012 of OSL
reader 7712. Alignment marks 8022, 8024, 8026 and 8028 on rail 7716
and alignment mark 8030 may be used to position sled slider 7714
for various functions. Sled slider 7714 includes a bifurcated tang
8034 that includes prongs 8036 and 8038 on either side of rail
7716. Sled slider 7714 also includes a pusher end 8040. Between
bifurcated tang 8034 and pusher end 8040 is a U-shaped detent 8042.
Prior to a dosimeter sled (not shown in FIGS. 80 and 81) being
pushed by dosimeter drawer 6910 into ready region housing 7294,
sled slider 7714 travels through an opening 8052 in wall 7708 so
that a respective U-shaped detent and tang of a dosimeter sled,
such as U-shaped detent 678 and tang 679 of dosimeter sled 600,
will be pushed to engage bifurcated tang 8034 and U-shaped detent
8042, respectively.
[0323] Each OSL sensor is moved to a respective reading position by
dosimeter reader 6902 determining the distance that sled slider
7714 has moved the dosimeter sled. The slider motor includes an
encoder that counts the number of revolutions or steps the drive
shaft of the motor makes. This information may be correlated to a
movement distance. Alignment marks 8022, 8024, 8026 and 8028 on
rail 7716 and alignment mark 8030 correspond to a number of steps
from a reference point.
[0324] In one embodiment of the present invention, the dosimeter
reader may include a photo-optic sensor for sensing when each of
the OSL sensors of the dosimeter sled are aligned with the optical
light pipe of the dosimeter reader. The photo-optic sensor may be
mounted below one of the rails on which the slider slides and may
be aligned with an alignment mark on one of the rails. FIGS. 82 and
83 show how the positioning notches of a dosimeter sled may be used
to align the OSL sensors with the optical path of an OSL reader so
that the stimulation light and luminescence light are consistently
applied and captured. FIG. 82 shows a dosimeter sled 8202 having a
sled body 8204 and three OSL sensors 8212, 8214 and 8214 in a
non-reading position. OSL sensor 8212 is aligned with a
semicircular positioning notch 8222, OSL sensor 8214 is aligned
with a semicircular positioning notch 8224 and OSL sensor 8216 is
aligned with a semicircular positioning notch 8226. A light path,
shown by dashed circle 8232, of the photo-optic sensor is blocked
by sled body 8204, indicating an optical light pipe 8234, the
position of which is shown by a dashed circle, is not aligned with
any of the three OSL sensors. Sled body 8204 has a curved end side
8242. OSL sensor 8212 is the closest OSL sensor to curved end side
8242. Between OSL sensor 8212 and curved end side 8242 is a region
8244. FIG. 83 shows a reading position for OSL sensor 8214. Notch
8224 creates an open space through which the light path, shown by
solid circle 8332, of the photo-optic sensor may pass, indicating
that optical light pipe 8234, the position of which is shown by a
double dashed circle, is aligned with sensor 8212. Notches 8224 and
8226 may be used in a similar way to indicate the reading positions
for OSL sensor 8214 and 8216, respectively. Curved end side 8242
ensures that region 8244 between OSL sensor 8212 and curved end
side 8242 is large enough so that optical light pipe 8234 is fully
covered when OSL sensor 8212 is read. As shown in FIGS. 82 and 83,
optical light pipe 8012 is about the same diameter as the interior
diameter of each of the OSL sensors.
[0325] FIG. 84 shows underside 8402 of dosimeter reader body 6904
including an elevator carriage 8412, control electronics 8414, a
photo-optical engine frame 8416, an electronic connector 8418 to
battery compartment 6912 and a printed circuit board (PCB) 8420 for
OSL reader 7712. A proximal mounting strip 8422 and screws 8424 and
8426 are used to mount drawer housing 7206 on a bottom face 8428 of
drawer base 7202 at a proximal end 8430 of drawer base 7202. Screws
8424 and 8426 are screwed into screw posts 8432 and 8434 of
proximal mounting strip 8422. Mounting strip 8422 and screws 8424
and 8426 are also used to mount a proximal flap 8440 on drawer base
7202 proximal end 8430 of drawer base 7202. Proximal flap 8440
includes edges 8442 and 8444. Slide tracks 8452 and 8454 are
mounted on dosimeter reader chassis 6908. One edge (not visible in
FIG. 84) of drawer base 7202 slides in a slide groove (not visible
in FIG. 84) in slide track 8452 and a second edge (not visible in
FIG. 84) of drawer base 7202 slides in a slide groove (not visible
in FIG. 84) in slide track 8454, thereby allowing drawer base 7202
to slide when pushed and pulled by drawer handle 7204. Edges 8442
and 8444 of proximal flap 8440 also slide in the slide grooves of
slide tracks 8452 and 8454, respectively. As can be seen by the
bending of proximal flap 8440 is flexible, allowing proximal flap
to bend or curl downwardly when forced against dosimeter reader
case 6906 by dosimeter drawer 6910 moving from dosimeter ready
region 6934 towards dosimeter loading/unloading region 6932.
Mounted on slide track 8452 is a proximal spring stop 8456. Mounted
on slide track 8454 is a proximal sensor switch 8458. Proximal
spring stop 8456 prevents elevator carriage 8412 from moving beyond
proximal spring stop 8456 and proximal sensor switch 8458 when
elevator carriage 8412 moves in the direction from dosimeter ready
region 6934 to dosimeter loading/unloading region 6932. Proximal
sensor switch 8458 is part of a sensor device 8462 that senses when
screw post 8434 contacts sensor switch 8458, indicating that drawer
housing 7206 is in dosimeter loading/unloading region 6932.
[0326] FIG. 85 is a close-up view of PCB 8420 for OSL reader
7712.
[0327] FIGS. 86, 87, 88 and 89 show the operation of elevator
carriage 8412. In FIGS. 86, 87, 88 and 89, dosimeter reader 6902 is
shown upside down so that motion of elevator carriage 8412 from
left to right corresponds to elevator carriage 8412 and dosimeter
drawer 3914 moving from loading/unloading region 6932 toward
dosimeter ready region 6934. Elevator carriage 8412 includes a
barrel 8614 and a loop retainer elevator 8612. Loop retainer
elevator 8612 includes two kidney-shaped posts 8616 and 8618. Post
8616 is part of loop retainer 7256. Post 8618 is part of loop
retainer 7260. Barrel 8614 includes a pinion gear 8622 mounted on
barrel top 8624 of barrel 8614. Teeth 8626 of pinion gear 8622
extend through an opening 8628 in loop retainer elevator 8612 to
mesh with teeth 8632 of a rack 8634. Looking at inner barrel from
underneath dosimeter reader body 6904, as pinion gear 8622 rotates
counterclockwise, elevator carriage 8412 travels along rack 8634
from dosimeter loading/unloading region 6932 toward dosimeter ready
region 6934 until elevator carriage 8412 reaches the position shown
in FIG. 86. As elevator carriage 8412 moves towards dosimeter ready
region 6934 from dosimeter loading/unloading region 6932, a tongue
(not shown) on an inner side (not shown) of loop retainer elevator
8612 travels in a groove 8642 on an exterior wall 8644 of barrel
8614 and loop retainer elevator 8612 is driven upward, thereby
causing loop retainers 7256 and 7260 to move upwards i.e. up
through respective openings 7258 and 7262 in drawer base 7202. FIG.
86 shows elevator carriage 8412 at dosimeter loading/unloading
region 6932 with loop retainer elevator 8612 at lowered position.
FIG. 87 shows elevator carriage 8412 between dosimeter
loading/unloading region 6932 and dosimeter ready region 6934 with
loop retainer elevator 8612 at a partially raised position. FIGS.
88 and 89 show elevator carriage 8412 moved fully towards dosimeter
ready region 6934 with loop retainer elevator 8612 at a fully
raised position.
[0328] FIG. 89 shows rack 8634 and slide track 8452 mounted on
chassis edge 7404 using screws 8912 and 8914. Slide track 8452 is
sandwiched between rack 8634 and chassis edge 7404. FIG. 89 also
shows a bottom face 8922 of loop retainer elevator 8612 a circular
opening 8924 in loop retainer elevator through which barrel 8714
extends. Screws 8932 and 8934 are used to mount pinion gear 8622 on
barrel 8714. An axis post 8942 extends through an opening 8944 in a
circular bearing 8946. A spacer clip 8948 ensures that space is
maintained between circular bearing 8946 and a base 8952 of axis
post 8942 as barrel 8714 and pinion gear 8622 rotate around post
8942. Axis post 8942 is part of an axis mount (not visible in FIG.
89) that is mounted in a fixed position on drawer base 7202.
[0329] The process shown in FIGS. 86, 87, 88 and 89 may also be
reversed. As elevator carriage 8412 moves from dosimeter ready
region 6934 towards dosimeter loading/unloading region 6932, the
tongue on the inner side of loop retainer elevator 8612 travels in
a groove 8642 on an exterior wall 8644 of barrel 8614, loop
retainer elevator 8612 is driven downward, thereby causing loop
retainers 7256 and 7260 to move downward i.e. down through
respective openings 7258 and 7262 in drawer base 7202.
[0330] FIGS. 90 and 91 details of retaining tab 7218, retaining tab
7220, pinion gear 8622 and drawer base 7202. As shown in FIG. 91,
retaining tab 7218 has a pin 9012 that extends from a tab base
9014. Retaining tab 7218 also has an upper body 9016 that extends
from tab base 9014. Exterior leg 7232 and interior leg 7234 extend
from tab upper body. Retaining tab 7220 has a pin 9022 that extends
from a tab base 9024. Retaining tab 7220 also has an tab upper body
9026 that extends from tab base 9014. Exterior leg 7242 and
interior leg 7244 extend from tab upper body. Retaining tab 7218 is
slidably mounted in curved slot 9032 of pinion gear 8622 using pin
9012. Retaining tab 7220 is slidably mounted in curved slot 9034 of
pinion gear 8622 using pin 9012. Tab bases 9014 and 9024 rest on
top of respective curved slots 9032 and 9034, so that exterior leg
top 7532, interior leg top 7534, exterior leg top 7542 and interior
leg top 7544 are maintained at the same height above pinion gear
8622 as pins 9012 and 9022 travel in curved slots 9032 and 9034,
respectively. Curved slot 9032 includes a flat portion 9042 and a
curved portion 9044. Curved slot 9034 includes a flat portion 9046
and a curved portion 9048. As pinion gear 8622 rotates along rack
8634, retaining tabs 7218 and 7220 are prevented from moving with
pinion gear 8622 by openings 7222 and 7224 in drawer base 7202,
respectively, and, therefore, pins 9012 and 9022 travel in
respective curved slots 9032 and 9034 as pinion gear 8622 rotates
along rack 8364.
[0331] When elevator carriage 8412 and pinion gear 8622 are in
dosimeter loading/unloading region 6932, pins 9012 and 9022 are in
flat portion 9042 of curved slot 9032 and flat portion 9046 of
curved slot 9034, respectively. As pinion gear 8622 rotates along
rack 8634 from dosimeter loading/unloading region 6932 to dosimeter
ready region 6934, pins 9012 and 9022 are forced to move along
curved portion 9044 of curved slot 9032 and curved portion 9048 of
curved slot 9034, respectively. Because curved portions 9044 and
9048 are farther apart from each other than flat portions 9042 and
9046, when pins 9012 and 9022 travel in curved portions 9044 and
9048, retaining tabs 7218 and 7220 are forced to spread outwardly
from each other as shown in FIG. 106 and described below.
[0332] FIGS. 90 and 91 also show additional features of pinion gear
8622 and drawer base 7202. Pinion gear 8622 includes openings 9052
and 9054 through which screws 8932 and 8934 (not shown in FIGS. 90
and 91) are screwed to mount pinion gear 8622 on barrel 8614 of
elevator carriage 8412. An axis mount 9062 includes axis post 8942
on which pinion gear 8622 rotates. Axis mount 9062 is mounted in a
recess 9064 in bottom face 8428 of drawer base 7202 using screw
7412 (not visible in FIGS. 90 and 91). A distal mounting strip 9072
including screw posts 9074 and 9076 is mounted on bottom face 8428
of drawer base 7202 using screws 9078 and 9080. Mounted on slide
track 8452 is a distal spring stop 9082. Mounted on slide track
8454 is a distal sensor switch 9094. Distal spring stop 9082
prevents elevator carriage 8412 from moving beyond distal spring
stop 9082 and distal sensor switch 9084 when elevator carriage 8412
moves in the direction from dosimeter loading/unloading region 6932
to dosimeter ready region 6934. Distal sensor switch 9084 is part
of a sensor device 9088 that senses when screw post 9076 contacts
distal sensor switch 9084, indicating that drawer housing 7206 is
in dosimeter ready region 6934.
[0333] Also visible in FIG. 90 is a slide groove 9092 of slide
track 8454. Slide track 8452 includes an identical slide groove
(not visible in FIG. 90). One edge of drawer base 7202 slides in
slide groove 9092 and a second edge of drawer base 7202 slides in
the slide groove of slide track 8452, thereby allowing drawer base
7202 to slide when pushed and pulled by drawer handle 7204.
[0334] In FIG. 90, pinion gear 8622 is separated from barrel 8614
and is shown resting on bottom face 8922 of loop retainer elevator
8612.
[0335] FIGS. 92 and 93 show photo-optical engine frame 8416, LED
board assembly base 9208 mounted on a bottom face 9210 of
photo-optical engine frame 8416 by screws 9212, a photomultiplier
tube (PMT) mount plate 9214, a PMT 9216, an LED interconnect PCB
assembly 9220 is mounted on a side face 9222 of photo-optical
engine frame 8416 using screws 9224, and a filter panel 9234
mounted on photo-optical engine frame 8416. LED interconnect PCB
assembly 9220 includes a power jack 9236.
[0336] FIGS. 94, 95, 96, 97, 98, 99 and 100 show a photo-optical
engine 9402 and various components of photo-optical engine 9402 of
OSL reader 7712. An optical light pipe assembly 9406 that includes
optical light pipe 8012 that extends through an optical light pipe
mount 9408 is mounted on a top face 9410 of photo-optical engine
frame 8416 using screws 9412 so that optical light pipe 8012
extends into opening 9414. A slide rail base 7720 is mounted on
optical light pipe mount 9408 using screws 9416. A photodiode
printed circuit board (PCB) assembly 9418 including a photodiode
9420 is mounted on a side face 9422 of photo-optical engine frame
8416 using screws 9424 so that photodiode 9420 extends into opening
9426. An LED board assembly 9428 including LED board assembly base
9208 is mounted on bottom face 9210 of photo-optical engine frame
8416 using screws 9212. A photomultiplier tube (PMT) lens 9430, a
PMT lens gasket 9432 and a blue glass filter 9434 are mounted in an
opening 9436 in a side face 9438 of photo-optical engine frame
8416. PMT mount plate 9214 is mounted on PMT 9216 using screws
9440. PMT mount plate 9214 and PMT mount plate gasket 9442 are
mounted on side face 9438 of photo-optical engine frame 8416 using
screws 9444. LED interconnect PCB assembly 9220 mounted on a side
face 9222 of photo-optical engine frame 8416 using screws 9224. PMT
mount plate includes an opening 9446 and PMT mount plate gasket
9442 includes an opening 9448 that is aligned with (PMT) lens 9430
and blue glass filter 9434. PMT 9216 includes photocathode
9450.
[0337] An OSL filter optic assembly 9452 includes an assembly mount
bottom 9454, an open circle-shaped lower gasket 9456, a green glass
filter 9458, an open circle-shaped middle gasket 9460, a dichroic
mirror 9462 aligned with green glass filter 9458, an open
circle-shaped upper gasket 9464 and an assembly mount top 9466.
Assembly mount top 9466 fits over assembly mount bottom 9454, and
together assembly mount top 9466 and assembly mount bottom 9454
enclose the remaining components of OSL filter optic assembly 9452:
lower gasket 9456, green glass filter 9458, middle gasket 9460,
dichroic mirror 9462 and upper gasket 9464. When OSL filter optic
assembly 9452 is mounted in an opening 9468 in a side face 9470 of
photo-optical engine frame 8416. Mounted in an opening 9468,
assembly mount top 9466 and assembly mount bottom 9454 are held
together by a lozenge-shaped interior wall 9472 of opening 9468,
thereby holding together the remaining components of OSL filter
optic assembly 9452 so that: lower gasket 9456 is sandwiched
between assembly mount bottom 9454 and green glass filter 9458,
middle gasket 9460 is sandwiched between green glass filter 9458
and a dichroic mirror 9462 and upper gasket 9464 is sandwiched
between dichroic mirror 9462 and assembly mount top 9466. When held
together, OSL filter optic assembly 9452 has a shape that
complentarily engages interior wall of 9472 of opening 9468.
Assembly mount bottom 9454 has a circular opening 9474 and assembly
mount top 9404 has a circular opening 9478 that allows light to
travel through OSL filter optic assembly 9416. Assembly mount top
9466 has two curved ends 9482 and 9484. OSL filter optic assembly
9452 in held in place in opening 9468 by filter panel 9234 and
filter panel gasket 9488 that are mounted on side face 9470 of
photo-optical engine frame 8416 using screws 9490.
[0338] The various gaskets of the present invention may be made of
a resilient material such as rubber or plastic. Each gasket shown
in FIGS. 94 and 95 used in connection with a filter, lens or mirror
includes an opening therein through which light may pass.
[0339] LED board assembly 9428 includes a LED (not shown) that
transmits the stimulation light used in photo-optical engine
9402.
[0340] Photodiode PCB assembly 9418 includes photodiode 9420 that
functions as an activity sensor. Photodiode PCB assembly 9418
includes a female electrical connector 9492 for connecting with a
male power jack (not shown) to provide photodiode PCB assembly 9418
with power.
[0341] As shown in FIGS. 97, 98 and 99, LED interconnect PCB
assembly 9220 includes a PCB 9722 that is electrically connected by
an electrical connection 9724 to LED board assembly 9428. LED
interconnect PCB assembly 9220 includes a power jack 9236 to
provide LED 10242 of LED board assembly 9428 with power. LED
interconnect PCB assembly 9220 includes an assembly body 9732,
having an opening 9734 in which power jack 9236 is mounted.
Assembly body 9732 includes a complementary recess 9736 in which
PCB 9722 is mounted and openings 9738 for receiving screws
9224.
[0342] The OSL filter optic assembly of FIGS. 94, 95, 96, 97, 100
and 101 is more compact than many previous filter optic assemblies
for OSL readers and less subject to becoming misaligned by motion
or vibrations, because the OSL filter optic assembly is also
mounted in an opening so that the OSL filter optic assembly does
not substantially move or vibrate when the photo-optical engine is
moved or vibrated.
[0343] Although a particular type of optical filter is described
above as being used in the filter optical assembly, optical filters
filtering a variety of different colors may be used in the optical
filter assembly of the present invention depending on the
wavelength used as a light source for the stimulation light and the
wavelength at which the OSLM of the OSL sensor absorbs light. Also,
although a particular type of optical filter is described above as
being used as a filter for the emitted light detector detecting
emitted light from the OSL sensor, optical filters filtering a
variety of different colors may be used with the emitted light
detector of the present invention depending on the wavelength at
which OSLM of the OSL luminesces.
[0344] FIG. 100 shows photo-optical engine 9402 in an assembled
configuration with a portion 10012 broken away to show a
cross-sectional view of OSL filter optic assembly 9452. A circled
region 10014 of portion 10012 of FIG. 100 is shown in greater
detail in FIG. 101. FIG. 101 provides a cross-sectional view of OSL
filter optic assembly 9452 showing: lower gasket 9456 sandwiched
between assembly mount bottom 9454 and green glass filter 9458,
middle gasket 9460 sandwiched between green glass filter 9458 and
dichroic mirror 9462 and upper gasket 9464 sandwiched between
dichroic mirror 9462 and assembly mount top 9466.
[0345] The alignment of lenses, mirrors and filters of the
photo-optical engine of FIGS. 94, 95, 96, 97, 98, 99, 100 and 101
is also not significantly affected by vibrations when a dosimeter
reader including photo-optical engine is moved, because all the
components of the photo-optical engine are fixed in place on or in
the photo-optical engine frame. These components include: the OSL
filter optic assembly, the optical light pipe assembly, the blue
glass filter, PMT, activity sensor, LED board assembly, etc. In one
embodiment of the present invention, an OSL reader employing the
photo-optical engine of FIGS. 94, 95, 96, 97, 98, 99, 100 and 101
may even be used to read an OSL while the OSL reader is being
moved. The lens, mirrors and filters of the photo-optical engine
are less subject to misalignments caused by vibrations than the
lenses, mirrors and filters of other OSL readers because the small
distances between components maximize the solid angles through
which the various light beams must pass for correct transmission
through the optical pathway. The close arrangement of the
components minimizes losses due to dispersion
[0346] In one embodiment of the present invention, four (4) AA
batteries provide all the power required for operating the
dosimeter reader including the power to operate: the OSL reader,
the engine that drives the drive gear that controls the motion of
the sled slider, the electronic controls of the dosimeter reader,
the electronic sensors of dosimeter reader, the display of the
dosimeter reader, and the communications port for interfacing with
external databases. Battery life depends on the number of analyses
performed, the stimulation protocol employed and the time between
analyses in which the reader is idle but still powered. Typically,
more than 250 analyses can be performed for one set of four AA
batteries. In one embodiment of the present invention, other types
of chargeable and non-chargeable batteries may be used as a power
supply for the dosimeter reader. For example, one or more alkaline
batteries, one or more lithium batteries, etc. may be used as a
power supply for the dosimeter reader. In one embodiment, the total
weight of the one or more batteries is less than about 100 g.
[0347] In one embodiment of the present invention, the dosimeter
reader requires a current of about 90 mA or less for about 1 second
to read an OSL sensor. In one embodiment of the present invention,
the dosimeter reader requires 80 mA or less of current when the
dosimeter reader is powered and in an idle state and ready to read
a radiation dosimeter. In one embodiment, when the dosimeter reader
is turned on, the current in the dosimeter reader may be 235 mA or
less for less than 10 seconds.
[0348] In one embodiment of the present invention, the dosimeter
reader, with the dosimeter case in a closed configuration, has a
maximum depth of about 19 cm or less, a maximum width of about 23.5
cm or less and a maximum height of about 11 cm or less. In one
embodiment, the dosimeter reader, with the dosimeter case in a
closed configuration has a total volume of about 3,065 cm.sup.3 or
less.
[0349] In one embodiment of the present invention, the dosimeter
reader, including the dosimeter reader case, has a weight of less
than about 2,600 g, excluding the weight of the one or more
batteries that power the dosimeter reader, thereby allowing the
dosimeter reader to be carried by a single individual. In one
embodiment of the present invention, the dosimeter reader,
including the dosimeter reader case, of the present invention has a
weight of less than about 2,700 including the weight of the one or
more batteries that power the dosimeter reader, thereby allowing
the dosimeter reader to be carried by a single individual.
[0350] FIG. 102 shows OSL reader 7712 and RFID tag reader 7604 of
dosimeter reader 6902 in operation reading a dosimeter sled 10204.
For simplicity of illustration with respect to OSL reader 7712,
only photo-optical engine 9402 of OSL reader 7712 are shown and
other components of OSL reader 7712, such as sled slider 7714, are
omitted from FIG. 102. Dosimeter sled 10204 includes three OSL
sensors: OSL sensor 10212, OSL sensor 10214 and OSL sensor 10216
and an RFID tag 10218. OSL sensors 10212, 10214 and 10216 include
an OSLM (not shown) comprising an Al.sub.2O.sub.3:C material.
Dosimeter sled 10204 is pulled out of a radiation dosimeter (not
shown) by sled slider 7714 in the direction shown by arrow 10222 so
that OSL sensor 10212, OSL sensor 10214 and OSL sensor 10216 are
each in turn read by OSL reader 7712 at a reading position 10226.
FIG. 102 shows OSL sensor 10212 in the process of being read.
[0351] OSL reader 7712 includes an LED 10242 that is part of LED
board assembly 9428. LED 10232 is a source of transmitted green
stimulation light 10234 having a wavelength of about 520 nm. Green
stimulation light 10234 is concentrated by a concentrator 10236
that is part of LED board assembly 9428 and then passes through
green glass filter 9458 and dichroic mirror 9462 aligned with green
glass filter 9458. Green glass filter 9458 filters out non-green
light from green stimulation light 10234, i.e., green glass filter
9458 is a green filter that passes green light. Green stimulation
light 10234 is then channeled by optical light pipe 8012 so that an
OSL sensor at reading position 10226, OSL sensor 10212 in FIG. 102,
is exposed to green stimulation light 10234, causing the OSLM
material in OSL sensor 10212 to luminesce and emit blue emitted
light 10246 with a wavelength of about 420 nm. Blue emitted light
10246 is reflected by dichroic mirror 9462, passes through a blue
glass filter 9434 that filters out non-blue light from blue light
in blue emitted light 10246, i.e., blue glass filter 9434 is a blue
filter that passes blue light. Blue glass filter 9434 also filters
out any stray light or green stimulation light 10234 that is not
removed by green glass filter 9458. Blue emitted light 10246 is
then detected and measured by photocathode 9450 of photomultiplier
tube (PMT) 9216. PMT 9216, operating in a photon counting mode,
quantifies the luminescence created in the OSL sensor based on the
detected blue emitted light 10246. A portion of transmitted green
stimulation light 10234 is reflected back by dichroic mirror 9462
through green glass filter 9458 so that green reflected light 10272
is detected by activity sensor/photodiode 9420.
[0352] Green stimulation light 10234 in FIG. 102 defines a light
path from LED 10242 to OSL sensor 10212. Blue emitted light 10246
defines a light path from OSL sensor 10212 to photocathode 9450.
Stimulation light 10234 exits optical light pipe 8012 at an exit
10282 and travels a distance 10284 from exit 10282 to OSL sensor
10212.
[0353] Before, during or after OSL sensor 10212 is read, RFID tag
reader 7604 reads RFID tag 5418 to retrieve identification
information stored in the RFID tag as shown by arrow 10224. This
information may be displayed on display 6920 (not shown in FIG.
102) or on a separate display in data communication with the
dosimeter reader 6902. After OSL sensor 10212, OSL sensor 10214 and
OSL sensor 10216 are read by OSL reader 7712, RFID tag reader 7604
updates RFID tag 10218 with information based on the readings of
OSL sensor 10212, OSL sensor 10214 and OSL sensor 10216. RFID tag
reader 7604 may also transmit updated information as each OSL
sensor of the three OSL sensors is read. After OSL sensor 10212,
OSL sensor 10214 and OSL sensor 10216 have been read, sled slider
7714 pushes dosimeter sled 10204 in the direction of arrow 10230
and back into the radiation dosimeter.
[0354] A database 10292 may optionally be in communication with
dosimeter reader 6902 or be a part of dosimeter reader 6902.
Information about the radiation dosimeter and/or individual wearing
the radiation dosimeter may be retrieved from database 10292 as
shown by dashed arrow 10294. Updated information about the
radiation dosimeter and/or individual wearing the radiation
dosimeter may be sent to database 10292 as shown by dashed arrow
10296.
[0355] In one embodiment of the present invention, the OSLM in each
OSL sensor at the reading position for the OSL sensor is
approximately 1 mm from the exit of the light guide/optical light
pipe.
[0356] The activity sensor/photodiode of the photo-optical engine
of FIG. 102 is designed to determine that the photo-optical engine
is functional when a non-zero reading is received by the activity
sensor/photodiode due to stimulated light reflected back to the
activity sensor/photodiode.
[0357] In one embodiment of the present invention, the emitted
light detector in FIG. 102 is part of a PMT that uses a high
sensitivity counting system. The amount of blue light emitted
during optical stimulation by the green stimulation light is
directly proportional to the radiation dose and the intensity of
the green stimulation light. A dose calculation algorithm is then
applied to the measurement to determine exposure results.
[0358] The photo-optical engine of FIG. 102 may employ stimulation
light having various pulse rates. The photo-optical engine of FIG.
102 may also employ various pulse durations of stimulation
light.
[0359] Although in FIG. 102 a particular photo-optical engine
employing particular transmitted and detected light wavelengths to
determine the dosages of various types of radiation to which a
particular type of OSLM is exposed, photo-optical engines
transmitting and detecting different wavelengths may be used with
different optically stimulated luminescent materials may be
employed. The photo-optical engine may also be a pulsed stimulation
system.
[0360] FIGS. 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
114 and 115 shown an example of a reading process of the present
invention using radiation dosimeter 102.
[0361] FIGS. 103 and 104 show radiation dosimeter 102 placed in a
starting position 10302 in loading/unloading region 6932. An
individual places radiation dosimeter 102 in starting position
10302 so that C-shaped ridge 7212 (not visible in FIGS. 103 and
104) engages C-shaped groove 454 (not visible in FIGS. 103 and 104)
of radiation dosimeter 102. Lozenge-shaped recesses 456 and 458
(not visible in FIGS. 103 and 104) of radiation dosimeter 102 (not
visible in FIGS. 103 and 104) fit over retaining tabs 7218 and 7220
(not visible in FIGS. 103 and 104), respectively, of dosimeter
reader 6902. Circular alignment symbol 224 of upper housing 104 is
aligned with alignment dot 7282. Curved arrow 222 indicates the
direction in which upper housing 104 should be rotated to release
upper housing 104 from lower housing 109 (not visible in FIGS. 103
and 104).
[0362] FIG. 105 shows upper housing 104 of radiation dosimeter 102
rotated so that radiation dosimeter 102 is in a rotated position
10502 in loading/unloading region 6932. By grasping loops 122 and
124, an individual rotates upper housing 104 approximately
90.degree. until circular alignment symbol 224 is aligned with
alignment dot 7286 so that radiation dosimeter 102 is in rotated
position 10502 where upper housing 104 is released from lower
housing 106. As upper housing 104 is rotated, loop 122 rotates into
and engages receiving slot 7264 of dosimeter loop retainer 7256.
Loop 122 is prevented from rotating further by end wall 7266 of
dosimeter loop retainer 7256 and loop stop 7298. Loop 122 also
engages spring tab 7270 and rests on base 7268 of loop retainer
7256. Also, as upper housing 104 is rotated, loop 124 rotates into
and engages receiving slot 7272 of dosimeter loop retainer 7260
(not visible in FIG. 105). Loop 124 is prevented from rotating
further by end wall 7274 (not visible in FIG. 105) of dosimeter
loop retainer 7260 and loop stop 7298. Loop 122 also engages spring
tab 7278 (not visible in FIG. 105) and rests on base 7276 (not
visible in FIG. 105) of loop retainer 7260. While upper housing 104
is rotated, lower housing 106 (not visible in FIG. 105) is
prevented from rotating by the engagement of C-shaped ridge 7212
(not visible in FIG. 105) with C-shaped groove 454 (not visible in
FIG. 105) of radiation dosimeter 102 and the engagement of
lozenge-shaped recesses 456 and 458 (not visible in FIG. 105) with
retaining tabs 7218 and 7220 (not visible in FIG. 105),
respectively, of dosimeter reader 6902. FIG. 105 shows drawer base
7202 in a position that corresponds to the position of elevator
carriage 8412 shown in FIGS. 88 and 89.
[0363] A user pushes drawer handle 7204 of dosimeter drawer 3914 so
that radiation dosimeter 102 is moved by drawer base 7202 into
ready region housing 7294. As radiation dosimeter 102 is pushed
into ready region housing 7294, retaining tabs 7218 and 7220 spread
outwardly so that foot 7236 of exterior leg 7232 retaining tab 7218
and foot 7246 of exterior leg 7242 of retaining tab 7220 engage
undercuts 10602 and 10604 of lozenge-shaped recesses 456 and 458,
respectively as shown in FIG. 106. Retaining tabs 7218 and 7220 are
spread outwardly from each other due to the interactions of
retaining tabs 7218 and 7220 with openings 7222 and 7224 of drawer
base 7202 and curved slots 9032 and 9034 of pinion gear 8622, as
described in greater detail above with respect to FIGS. 90 and 91.
In the state shown in FIG. 106, foot 7236 captures lip 10612 of
lozenge-shaped recess 456, and foot 7246 captures lip 10614 of
lozenge-shaped recess 458, thereby allowing retaining tab 7218 and
retaining tab 7220 to hold lower housing 106 on drawer base 7202 as
upper housing 104 (not shown in FIG. 106) is lifted up from lower
housing 106 as radiation dosimeter 102 is moved from dosimeter
loading/unloading region 6932 to dosimeter ready region 6934.
Retaining tabs 7218 and 7220 are spread outwardly by the
interaction of retaining tabs 7218 and 7220 with respective curved
slots 9032 and 9034 of pinion gear 8622 as pinion gear 8622 travels
along rack 8634, as described above with respect to FIGS. 93 and
94.
[0364] Although a particular combination of complementary lower
housing rotation preventing engagement structures, i.e. a C-shaped
recess on the lower housing engaging a C-shaped ridge on the drawer
base, are used in the embodiment of the present invention shown in
FIGS. 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114
and 115, other combinations of rotation preventing engagement
structures may be used in the present invention. For example, the
drawer base could includes two or more posts and the lower housing
could includes recesses for receiving and engaging the posts.
[0365] Although a particular combination of lower housing retaining
structures, i.e. the retaining tabs engaging the lips and undercuts
of the lozenge-shaped recesses, are used in the embodiment of the
present invention shown in FIGS. 103, 104, 105, 106, 107, 108, 109,
110, 111, 112, 113, 114 and 115, other combinations of lower
housing retaining structures may be used in the present
invention.
[0366] FIG. 107 shows radiation dosimeter 102 in rotated position
10502 of FIG. 105 from the side. FIG. 108 shows radiation dosimeter
102 is moved by drawer base 7202 into ready region housing 7294. As
shown in FIG. 108, upper housing 104 has been lifted above lower
housing 106 by loop retainers 7256 and 7260 being elevated by loop
retainer elevator 8612 (not visible in FIG. 108) as radiation
dosimeter 102 moved by drawer base 7202 into ready region housing
7294. FIG. 109 shows radiation dosimeter 102 moved further by
drawer base 7202 into ready region housing 7294 and upper housing
104 being lifted further above lower housing 106 by loop retainers
7256 and 7260 being further elevated by loop retainer elevator 8612
(not visible in FIG. 109). Foam cushioning 7296 is removed in FIG.
109 to show greater detail of upper housing 104 and lower housing
106.
[0367] FIGS. 110, 111 and 112 show drawer base 7202 fully pushed
into ready region housing 7294. Housing cover 6940 is shown removed
in FIG. 111 to show radiation dosimeter 102 in a dosimeter ready
position 11102 in dosimeter ready region 6934 of radiation
dosimeter reader 6902. In dosimeter ready position 11102, radiation
dosimeter 102 is fully shielded from light by ready region housing
7294, housing cover 6940 and drawer housing 7206. Upper housing 104
is fully raised above lower housing 104 by loop retainers 7256 and
7260 at dosimeter ready position 11102. FIGS. 110, 111 and 112 also
show how proximal flap 8440 forms a floor beneath opening 7402.
[0368] FIG. 112 shows radiation dosimeter 102 at dosimeter ready
position 11102 with upper housing 104 removed to show how lower
housing 106 and dosimeter sled 600 interact with various components
of dosimeter reader 6902 at dosimeter ready position 11102. At
ready position 11102, bifurcated tang 8034 of sled slider 7714
engages U-shaped detent 678 of dosimeter sled 600, U-shaped detent
8042 of sled slider 7714 engages tang 679 of dosimeter sled 600,
and a pusher end 8040 of slider 7714 abuts end side 668 of
dosimeter sled 600. The engagement of bifurcated tang 8034 with
U-shaped detent 678 and the engagement of U-shaped detent 8042 with
tang 679 allows slider 4214 to pull dosimeter sled 600 in a linear
direction into reading region 6936. At dosimeter ready position
11102, lower housing 106 continues to prevented from rotating by
C-shaped ridge 7212 engaging C-shaped groove 454. At dosimeter
ready position 11102, lower housing 106 continues to be held on
drawer base 7202 by retaining tabs 7218 and 7220 continuing to
capture lips 10612 and 10614 of lozenge-shaped recesses 456 and
458, respectively.
[0369] The position of drawer base 7202 shown in FIGS. 110, 111 and
112 corresponds to the position of elevator carriage 8412 shown in
FIGS. 88 and 89.
[0370] FIG. 113 shows dosimeter sled 600 being pulled out of sled
recess 412 of lower housing 106 by sled slider 7714 (not visible in
FIG. 113) through opening 8052 in wall 7708 and into dosimeter
reading region 6936.
[0371] FIG. 114 shows dosimeter sled 600 pulled to a reading
position 11402 for comparator OSL sensor 630 where OSL reader 7712
(not visible in FIG. 114) is directly beneath OSL sensor 630 so
that exposed side 658 of OSLM 652 (not visible in FIG. 114) is
exposed to OSL reader 7712. Positioning notch 684 (not visible in
FIG. 114) is aligned with alignment mark 8022 and alignment mark
8030. At reading position 11402, RFID tag 660 is also read by RFID
tag reader 7604 (which is removed in FIG. 114 to show greater
detail inside dosimeter reading region 6936).
[0372] FIG. 115 shows dosimeter sled 600 pulled to a reading
position 11502 for reference OSL sensor 628, where OSL reader 7712
(not visible in FIG. 115) is directly beneath OSL sensor 628 so
that exposed side 650 of OSLM 642 (not visible in FIG. 115) is
exposed to OSL reader 7712. Positioning notch 682 (not visible in
FIG. 115) is aligned with alignment mark 8022 and alignment mark
8030. At reading position 11502, an etched alignment mark 11512 on
dosimeter sled 600 for OSL sensor 628 is aligned with alignment
mark 8022 and alignment mark 8030. FIG. 115 also shows an etched
alignment mark 11514 on dosimeter sled 600 for OSL sensor 626.
[0373] After reference OSL sensor 628 is read, slider 7714 pulls
dosimeter sled 600 to a reading position (not shown) where
neutron-sensitive OSL sensor 626 is in position to be read above
OSL reader 7712. In the reading position for neutron-sensitive OSL
sensor 626, exposed side 640 of OSLM 632 is exposed to OSL reader
7712. At the reading position for OSL sensor 626, positioning notch
680 is aligned with alignment mark 8022 and alignment mark 8030.
Also, at the reading position for OSL sensor 626, etched alignment
mark 11514 is aligned with alignment mark 8022 and alignment mark
8030.
[0374] After comparator OSL sensor 630, reference OSL sensor 628
and neutron-sensitive OSL sensor 626 have each been read by OSL
reader 7712, sled slider 7714 pushes dosimeter sled 600 back into
sled recess 412 of lower housing 106 in a configuration identical
to the one shown in FIGS. 110, 111 and 112. By pulling on drawer
handle 7204, drawer handle 7204 may then be pulled back so that
drawer base 7202 is at dosimeter loading/unloading region 6932 in a
configuration identical to the one shown in FIGS. 105 and 107. As
drawer base 7202 is moved towards dosimeter loading/unloading
region 6932, dosimeter upper housing 104 is lowered by loop
retainers 7256 and 7260 being lowered by loop retainer elevator
8612. Also, as radiation dosimeter 102 drawer base 7202 is moved
towards dosimeter loading/unloading region 6932, retaining tabs
7218 and 7220 retract inwardly so that foot 7236 of exterior leg
7232 retaining tab 7218 and foot 7246 of exterior leg 7242 of
retaining tab 7220 no longer engage undercuts 10602 and 10604 of
lozenge-shaped recesses 456 and 458, respectively. Once radiation
dosimeter 102 has been moved back to dosimeter loading/unloading
region 6932, upper housing 104 may be then screwed onto lower
housing 106, by grasping loops by an individual grasping loops 122
and 124 and rotating upper housing 104 90.degree. in a direction
opposite to curved arrow 222 so that radiation dosimeter 102 is in
the configuration shown in FIGS. 103 and 104. Radiation dosimeter
102 may then be removed from drawer base 7202.
EXAMPLE
Example
[0375] Dosimeter tests were conducted to determine the responses of
three OSL sensors to radiation of different energies.
[0376] Groups of five dosimeters each were irradiated to a deep
dose (defined as Hp10, or the dose occurring at a depth of 10 mm in
tissue) of 500 mrem (5 mSv) from gamma or x-rays with mean energies
of 53 keV, 73 keV, 118 keV, 162 keV and 662 keV. The dosimeters
were mounted on a cylindrical phantom representing the wrist
composed of polymethymethacrylate that is 7.3 cm in diameter and 45
cm tall. After exposure, the dosimeters were read out using a
dosimeter reader of the type described above and shown in the
drawings. FIG. 116 plots the mean luminescence in units of photon
counts per mrem of delivered deep dose for each of the three OSL
sensors in the dosimeter. The sensor labeled Al refers to the OSL
sensor consisting of a single energy compensating cup composed of
aluminum with a PTFE conversion filter between the OSLM and the
aluminum cup. Likewise, the sensor labeled CuT refers to the OSL
sensor consisting of an inner energy compensating cup of aluminum
and an outer energy compensating cup of copper with a PTFE
conversion filter between the OSLM and the inner cup of aluminum.
The sensor labeled CuP is similar to the CuT sensor except that an
HDPE neutron conversion filter is substituted for the PTFE
conversion filter. The Al sensor shows an increasing response to
x-rays with energies below 100 keV, demonstrating the energy
compensation effect of the copper outer cup. FIG. 117 portrays the
same data normalized to the response for the 662 keV gamma rays.
This demonstrates the energy compensation effect of the filters to
create the same response per unit dose at all energies tested. FIG.
118 portrays the relative response of the Al and CuP sensors to the
reference sensor, CuT. This graph demonstrates the equality of the
gamma ray and x-ray response between the CuT and CuP sensors so
that any response in the CuP that is greater than that measured for
the CuT can be attributed to the neutron dose.
[0377] While the present invention has been disclosed with
references to certain embodiments, numerous modifications,
alterations, and changes to the described embodiments are possible
without departing from the spirit and scope of the present
invention, as defined in the appended claims. Accordingly, it is
intended that the present invention not be limited to the described
embodiments, but that it has the full scope defined by the language
of the following claims, and equivalents thereof.
* * * * *