U.S. patent number 3,737,660 [Application Number 05/078,666] was granted by the patent office on 1973-06-05 for apparatus for taking tomograms of parabolically curved objects.
This patent grant is currently assigned to Hida Denki Kogyo Kabushiki Kaisha, a/k/a Mida Electronic Apparatus. Invention is credited to Shoichi Ando, Shinji Yoshioka.
United States Patent |
3,737,660 |
Ando , et al. |
June 5, 1973 |
APPARATUS FOR TAKING TOMOGRAMS OF PARABOLICALLY CURVED OBJECTS
Abstract
For taking tomograms of parabolically curved objects such as the
dentition, jawbones and other bony structures of the head and
dento-facial region, there are provided an X-ray tube and a
radiographic film holder at both ends of a turnable arm. This arm
is furnished with a plurality of shafts alternately serving as a
pivot therefore, in such a manner that the X-ray tube supported at
one end of the arm turns round a parabolically curved object at an
unvarying distance therefrom, while radiating X-rays which traverse
the object to impinge upon the radiographic film carried by the
aforesaid holder turning in coordination with the turn of the arm.
There are also disclosed herein a device for holding the head of a
patient, a device for minute adjustment of ear-rods and the like
for use in positioning the head, and a device for modification of
the image density of X-rays traversing the head in readily
penetrable directions.
Inventors: |
Ando; Shoichi (Shibuya-ku,
Tokyo-to, JA), Yoshioka; Shinji (Ichikawa-shi,
JA) |
Assignee: |
Hida Denki Kogyo Kabushiki Kaisha,
a/k/a Mida Electronic Apparatus (Tokyo, JA)
|
Family
ID: |
27456650 |
Appl.
No.: |
05/078,666 |
Filed: |
October 7, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Feb 19, 1970 [JA] |
|
|
45/16790 |
Dec 12, 1969 [JA] |
|
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44/118085 |
Dec 1, 1969 [JA] |
|
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44/114226 |
Oct 9, 1969 [JA] |
|
|
44/80982 |
|
Current U.S.
Class: |
378/39;
378/180 |
Current CPC
Class: |
A61B
90/14 (20160201); A61B 6/14 (20130101); A61B
2017/00902 (20130101) |
Current International
Class: |
A61B
19/00 (20060101); A61B 6/14 (20060101); G03b
041/16 () |
Field of
Search: |
;250/65R,50,61.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Church; C. E.
Claims
We claim:
1. In apparatus equipped with a radiant rays source and a
radiographic film holder thereby to take a tomogram of an object in
the shape of an approximately parabolic curve consisting of not
less than two arcs of different curvatures; a head holding device
comprising, in combination:
a column slidably supporting the head holding device proper;
a movable member mounted on a pair of rails within a casing so as
to be capable of moving toward and away from said column, said
movable member having a means thereby to be secured at any desired
position in the course of its travels;
a pair of racks disposed in side-by-side relationship across said
movable member and having their toothed surfaces opposed to each
other;
a pinion provided between said racks so as to be in mesh with both
of them, said pinion having a means thereby to be turned manually
from outside of said casing;
a pair of rods provided downwardly at the opposite ends of said
racks, each of said rods having at the lower end a flanged ear-rods
to be inserted into the outer orifice of the ear;
a chin rest provided to a holding member so as to be vertically
movable, said holding member being installed in a supporting
portion of said casing so as to be movable toward and away from
said column and to be fixed at any desired position in the course
of its travels; and
a head support including means for adjustment of its position in
both vertical and horizontal directions.
2. A head holding device as claimed in claim 1, in which said
holding member is provided with an indicator means, the
calibrations for which are given on said supporting portion, and
said holding member is provided with another set of calibrations
for said chin rest connected slidably thereto, whereby a setting of
said chin rest in both horizontal and vertical directions can be
read numerically.
3. A head holding device as claimed in claim 1, in which said
flanged ear-rods are transparent.
4. A head holding device as claimed in claim 3, in which
illuminating means are provided in the hollowed interiors of said
transparent flanged ear-rods.
5. A head holding device as claimed in claim 1, in which said
movable member is provided with an indicator means capable of
indicating its position in directions toward and away from said
column.
6. A head holding device as claimed in claim 1, in which said
vertical rods are calibrated for indication of the heights of said
ear-rods provided slidably thereto.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to tomography, and in particular
to a novel apparatus capable of taking tomograms of objects in the
shape of an approximately parabolic curve such as a panoramic view,
especially, the dentition, jawbones and other parts of the face and
head. The invention also relates to some improvements designed to
add to the utility of the above apparatus.
There has long been awaited by roentgenologists and related
specialists the advent of apparatus capable of taking curved
surface tomograms of the dentition, jawbones, etc., of the face and
head. Many attempts made conventionally at the provision of such
apparatus have been frustrated, in nearly all cases, due to the
fact that those bony structures in the human face and head
represent a parabolic curve consisting of two or more arcs of
different curvatures.
Another difficulty resides in the correct adjustment and holding of
the head at a position of the greatest convenience for tomographic
examination. It has also been considered no less difficult to
appropriately modify the unsubdued image density of X-rays radiated
through tbe head in its readily penetrable directions. These
intense X-rays will cause unevenness in the tone of a radiographic
film exposed thereto.
Hence, no satisfactory tomograms of the dentition, jawbones and
other desired objects in the face and head have so far been
obtainable.
SUMMARY OF THE INVENTION
It is accordingly a primary object of the present invention to
provide a novel apparatus capable of taking clear and well-defined
panoramic tomograms of tbe dentition, jawbones and other
parabolically curved objects.
Another important object of the invention is to provide a device
for holding the head of a patient at a minutely adjusted and
visually confirmed position of the greatest convenience for its
tomographic examination.
Still another important object of the invention is to provide a
device capable of preventing, as far as feasible, the unevenness in
the density of a radiographic film produced by undesired changes in
the intensity of X-rays depending upon the arrangement of bony
structures or air cavities present in the head.
With these objects in view and the other objects hereinafter set
forth, the invention will now be described in detail with
connection to the accompanying drawings showing several preferred
embodiments thereof, in which like reference characters indicate
like parts.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is an explanatory view showing, in perspective, a parabolic
curve representing the dentition, jawbones, etc., of an
individual;
FIG. 2 is a diagram illustrated by way of explanation of the
operating principles of the apparatus in accordance with the
present invention;
FIGS. 3, 4 and 5 are similar diagrams in which the arm supporting
an X-ray tube and a radiographic film holder at both ends, as shown
in FIG. 2, is turned to different positions for taking tomograms of
different arcs of the parabolic curve;
FIG. 6 is a top view of a device for turning an X-ray tube and a
radiographic film holder of the apparatus of the invention along a
parabolically curved object, the X-ray tube and the radiographic
film holder being in positions shown in FIG. 2;
FIG. 7 is a vertical sectional view of the device of FIG. 6;
FIG. 8 is a top view of the device of FIG. 6, with the X-ray tube
and the radiographic film holder in positions shown in FIG. 4;
FIG. 9 also is a top view of the device of FIG. 6, with the X-ray
tube and the radiographic film holder in positions intermediate
between those shown in FIGS. 3 and 4;
FIG. 10 is a front elevational view of a head holding device in the
apparatus of the invention;
FIG. 11 is a side elevational view of the head holding device of
FIG. 10;
FIG. 12 is a top view of the head holding device of FIG. 10;
FIG. 13 is a perspective view of a device for adjustment of
ear-rods for use in holding the head of an individual to be
tomographically examined by the apparatus of the invention;
FIG. 14 is a sectional view of one of the ear-rods shown in FIG.
13; and
FIG. 15 is a top view showing the arrangement of filter means
adapted to modify the intensity of X-rays traversing the head in
readily penetrable directions.
DETAILED DESCRIPTION OF THE INVENTION
It will redound to the full appreciation of the present apparatus
to clarify the concepts supporting it. So, first of all,
description is given on how a tomogram of a parabolically curved
object with two or more arcs of different curvatures can be taken
with reference to FIGS. 1 through 5.
A parabolic curve 3 shown in perspective in FIG. 1 represents the
dentition, jawbones and other objects in the head of an individual,
and said parabolic curve 3 is indicated by broken lines in FIGS. 2
through 5. Let it be assumed that the parabolic curve 3 consists of
an arc A2-A3 having its center at a point 7 and a radius of r2, an
arc A3-A4 having its center at a point 6 and a radius of r1, and an
arc A1-A2 having its center at a point 8 and a radius r1.
Now, referring to FIG. 2, an arm 42 is disposed as illustrated
which has an X-ray tube 1 at one end and at the other end a screen
5 having a slit 4 therethrough in order to permit the passage of a
beam of the X-rays emitted from a slitted opening of the X-ray tube
1. Inside the screen 5 there is provided a radiographic film holder
2 so as to be turnable in the arrow marked direction a1 in
coordination with the turn of the arm 42 in the arrow marked
direction a2. Hence, a tomogram of the arc A1-A2 can be taken as
the arm 42 turns on its pivot 8 in the clockwise direction a2 to a
position shown in FIG. 3 while the radiographic film holder 2 also
turns in the clockwise direction a1 in coordination therewith.
Then, with the arm 42 at the position shown in FIG. 3, another
pivot of the arm 42 located at a point x which is at a distance (r1
- r2) from the center 8 of the arc A1-A2 is adjusted at the center
7 of the arc A2-A3, a tomogram of which is obtainable by turning
the arm 42 on the above adjusted pivot 7 to the position given in
FIG. 4. At this position, the first mentioned pivot of the arm 42
which was located at the center 8 in FIG. 3 is now brought to the
center 6 of the arc A3-A4, so that a tomogram of this arc A3-A4 can
be taken by turning the arm 42 on this same pivot at 6 to the
position of FIG.5 while also turning the film holder 2 in the same
clockwise direction.
In this manner, a series of tomograms of the parabolic curve 3
consisting of the arcs A1-A2, A2-A3 and A3-A4 can be taken by
turning the arm 42 pivoted at the successive ones of the centers 8,
7 and 6 of those arcs. Described in the following, with reference
to FIGS. 6 through 9, is a device for so turning the arm 42, as
adapted for materialization of the foregoing fundamental concepts
of the present invention.
As seen in the drawings, the arm 42 is turnably supported on a disk
43 by means of self-aligning ball bearings 43a and is provided with
two vertical shafts 8a and xa at positions corresponding to the
center 8 of the arc A1-A2 and the point x of FIG. 2. Further, at
the mid-part of the disk 43, there is provided a hole 44
therethrough, so shaped as to consist of three arcs drawn round the
aforesaid centers 6, 7 and 8 of the arcs A3-A4, A2-A3 and A1-A2. A
means 45 (for example, a spring) is provided whereby either one of
the vertical shafts 8a and xa is temporarily secured to the disk 43
as desired. Roller or ball bearings 46 are provided at the lower
ends of the vertical shafts 8a and xa so as to be in internal
comtact with the hole 44. At one end of the arm 42 there is
provided an X-ray tube 1 having a slit 1a through which X-rays are
emitted, while at the other end there is provided a screen 5 having
a corresponding slit 4 through which the X-rays are admitted to a
film holder 2 supported by the screen 5 so as to be turnable in
coordination with the turn of the arm 42. The desired turn of the
arm 42 is obtained by means of a motor M installed upon a motor
base 48 slidable in accordance with the turn of the arm 42 along a
guide 47 upon the arm 42. The rotation of the motor M is conveyed,
via bevel gears G2 and G3 and a shaft 49, to a pinion G4 which is
in mesh with a ring gear G1. The shaft 49 is provided with a roller
50 which is rotatable in internal contact with the ring gear G1,
while a shaft 51 secured to the motor base 48 is provided with a
roller 52 which is rotatable in external contact with the same ring
gear G1, so that these rollers 50 and 52 sandwich the ring gear G1
there-between. Accordingly, even though the arm 42 will turn on
either one of its pivots located at the points 6, 7 and 8 that are
off the center of the ring gear G1, the motor M slides by the turn
of the arm 42 to such a position that the ring gear G1 is kept in
constant mesh with the pinion G4.
To explain the operations of the above described device of the
invention, the vertical shaft 8a of the arm 42 is secured, while
the other shaft xa is free to move, when the arm 42 is at its
starting position shown in FIG. 6. The rotation of the motor M set
in motion, then, is conveyed to the pinion G4, as already
mentioned. By the rotational force of this pinion G4, which is in
mesh with the ring gear G1, the arm 42 starts turning clockwise, in
FIG. 6, to a position shown in FIG. 8, while taking a tomogram of
the arc A1-A2 on a radiographic film carried by the holder 2.
At the position of FIG. 8, the shaft xa of the arm 42 is located at
the center 7 of the arc A2-A3 (because the distance between the
shaft 8a and the shaft xa is equal to a difference between r1 and
r2). Hence, by resuming the rotation of the motor M upon securing
the shaft xa and releasing the shaft 8a, the arm 42 similarly
starts turning round the shaft xa due to the rotational force
obtained by the intermeshing of the pinion G4 and the ring gear G1,
past the position of FIG. 9, until the shaft 8a of the arm 42
arrives at the center 6 of the arc A3-A4. In the meantime, a
tomogram of the arc A2-A3 is obtained on the radiographic film of
the holder 2. Now, with the shaft 8a of the arm 42 located at the
center 6 of the arc A3-A4, this shaft 8a is secured while the other
shaft xa is released, and the arm 42 is similarly turned round the
shaft 8a to the position shown in FIG. 5, thereby taking a tomogram
of the final arc A3-A4.
It will now be clear how a complete tomogram of the arcs A1-A2,
A2-A3 and A3-A4 is obtained during the turn of the arm 42.
To elaborate further on the above described operations from a
mechanical point of view, the vertical shafts 8a and xa serving as
a pivot for the turn of the arm 42 are secured alternately at the
three points 6, 7 and 8 (which are off the center of the ring gear
G1) within the hole 44 of the disk 43. Consequently, as may be seen
from FIG. 8, a distance between the pivot of the arm 42 and the
intermeshing point of the ring gear G1 and the pinion G4 is subject
to variation along with the turn of the arm 42. Should the motor M
be installed fixedly on the arm 42, therefore, the pinion G4 would
be meshed incompletely with the ring gear G1, either too deep or
disengaged altogether therefrom, thus hampering the smooth turn of
the arm 42. This is the reason why, according to the present
invention, the motor M is installed on the motor base 48 which is
slidable along the guide 47 upon the arm 42 and, further, the ring
gear G1 is provided with the two rollers 48 and 52 which are caused
to rotate in internal and external contact, respectively,
therewith. The motor M is thus enabled to adjust its position
according to the radius of the turn of the arm 42, while the pinion
G4 is always kept in proper mesh with the ring gear G1, so that the
uninterrupted turn of the arm 42 is insured.
While in the above described example of the device for turning the
arm 42 along an approximately parabolic curve in accordance with
the concepts of the invention, the ring gear G1 secured to the disk
43 is kept in constant mesh with the pinion G4 by means of the
motor M that is made slidable along the guide 47 upon the arm 42
simultaneously with the turn of this arm 42, the same purpose can
also be accomplished by securing the ring gear G1 to the arm 42 and
installing the motor M upon the disk 43 so as to be slidable
together with the turn of the arm 42.
The foregoing configurations make possible to take a series of
tomograms of the entire jawbones or the dentition of an individual,
provided, however, that his head is held securely in position. Such
a head holding device in accordance with the invention will now be
described with reference to an example illustrated in FIGS. 10
through 12.
As seen in the drawings, a casing 53 contains rails 54, and
slidably mounted on these rails 54 is a movable member 55 which is
provided with a threaded rod 56 so as to be capable of being
secured at a desired position and further with a pair of racks 57
and 58 (still to be described with reference to FIG. 13) with their
toothed surfaces opposed to each other. Between these racks 57 and
58 there is provided a pinion 59 so as to be in mesh with both of
the racks 57 and 58 and to be turned manually from outside of the
casing 53. Vertical rods 60 and 61 are provided downwardly at the
opposite ends of the racks 57 and 58, respectively, and these rods
60 and 61 are provided at their lower ends with transparent
ear-rods 63, 63 having flanges 62, 62 and so shaped as to fit in
the outer orifice of the ear. A supporting portion 64 (refer to
FIG. 11) connected to the aforesaid casing 53 has a holding member
65 which is caused to be slidable toward and away from a column 9
and to be stopped at any desired position in the course of its
forward and backward travels. The holding member 65 is attached
with a chin rest 68 which may include a vertical portion 66 and a
horizontal portion 67. Further, this same holding member 65 is
provided with an indicator means 69, the graduations 70 for which
are given on the supporting portion 64 (refer to FIG. 12).
A bracket 10 is supported by the aforementioned column 9 so as to
be vertically movable. Adapters 71 and 72 for the ear-rods 63, 63
are so attached to the vertical rods 60 and 61 as to be freely
movable throughout the length thereof and to be fixed at any
desired position, while these rods 60 and 61 are calibrated for
indication of the heights of those ear-rods 63, 63. An indicator
means 73 provided to the movable member 55 is for indication of its
movements toward and away from the mentioned column 9. A worm gear
74, on the same shaft as the aforesaid pinion 59, is in mesh with a
worm 75 which is mounted on a manual rotation shaft 76 so as to be
slidable along its length and also to be rotated together with the
shaft 76. These transmission means, however, may be served as well
by bevel gears and the like. The manual rotation shaft 76 is
provided with a handle 77. The aforesaid chin rest 68 is attached
to the holding member 65 by means of a screw 78 so as to be
vertically movable, to be fixed exactly at a desired position by
means of graduations 79 (refer to FIG. 10) calibrated on the
holding member 65. A head support 80 (refer to FIG. 11) cooperates
with the ear-rods 63, 63 and the chin rest 68 in order to set the
head of a patient at a correct position. This head support 80 is
supported by means of an adapter 81 so as to be vertically movable,
while the position of this adapter 81 is made adjustable in
directions toward and away from the column 9 by means of a screw
82. As seen in FIGS. 10 and 12, the arm 42 is provided at one end
with the X-ray tube 1 and at the other end with the radiographic
film holder 2 and the screen 5, so as to be turnable
altogether.
The operations and functions of the head holding device, described
in the foregoing with reference to FIGS. 10, 11 and 12, are
explained hereinbelow.
For keeping the head of a patient at a proper position, the pinion
59 is first turned manually by means of the handle 77 thereby to
adjust the racks 57 and 58 at their desired positions. Thus, upon
insertion of the ear-rods 63, 63 into the earholes to a depth
determined by their flanges 62, 62, the head is now positioned
without any sideways inclination. The head is then further
readjusted as to its inclinations in front and rearward directions
by means of the chin rest 68 which may consist of the vertical
portion 66 and the horizontal portion 67. These simple operations
are enough to position the head ready for its tomographic
examination, as well as to select desired planes in the head for
that purpose repeatably.
Since the ear-rods 63, 63 are attached to the vertical rods 60 and
61 secured respectively to the different ends of the racks 57 and
58 meshed with one and the same pinion 59, the ear-rods are
adjustable simultaneously in coordinated movements by turning the
handle 77 of the pinion 59. When the ear-rods are inserted into the
earholes of a patient, his head is not only oriented in the proper
direction without any sideways inclination but is located at the
exact position for tomographic examination. In this case, if
ear-rods 63, 63 are made of a transparent material, the ear-rods
63, 63 enable the examiner to visually confirm if they are inserted
properly into the earholes, even though they are provided with the
flanges 62, 62. Further, according to the present invention, the
movable member 55 having all these racks 57 and 58 and the pinion
59 is mounted on the rails 54 so as to be movable toward and away
from the column 9, so that the head held by the ear-rods 63, 63 can
be adjusted at a position most suitable for taking tomograms of
desired planes therein. Accordingly, a series of tomograms thus
taken of a parabolically curved object are extremely clear and
without substantially any duplex portions from one to the other.
Furthermore, the exact positions of the movable member 55 and the
chin rest 68 are clearly indicated on their respective graduations,
so that, even when a patient is to have his head examined at
intervals, the head can be set at the same position as before each
time he sits for foregoing another tomographic examination. It is
accordingly possible to grasp with much appropriateness the
progress of a physical or pathological defect or a difference in
its conditions before and after treatment.
FIG. 13 illustrates another example of a means for the adjustment
of the vertical rods 60 and 61 and, therefore, the ear-rods 63, 63
in accordance with the present invention. In this example, as in
the foregoing one shown in FIG. 10 in particular, the ear-rods 63,
63 having flanges 62, 62 are provided at the lower ends of the
vertical rods 60 and 61. Further, in FIG. 13, the reference numeral
84 indicates a bracket; 86 a holding portion; 85 a shaft rotatably
installed through the holding portion; 87 a turnable disk secured
to the shaft 85; 88 holes formed on the upper surface of the disk
87; and 89 a fixing means provided to the holding portion 86 in
order to fix the turnable disk 87 by being inserted in one of its
holes 88. Two parallel racks 57 and 58 and, fixedly provided
thereto, sliding portions 60a and 61a of the vertical rods 60 and
61 are slidably mounted on a guide 83 secured to the bottom of the
disk 87. Provided between these two racks 57 and 58 is a pinion 92
which is in mesh with both of the racks and which is provided with
a knob 93.
Thus, by appropriately turning the knob 93 of the pinion 92 in
either direction, the racks 57 and 58 and, therefore, the sliding
portions 60a and 61a of the rods 60 and 61 move correspondingly in
the opposite directions so that the ear-rods 63, 63 may fit in the
outer orifices of the earholes of a patient for the proper
adjutment of his head.
Further, with reference to FIG. 14, the ear-rods 63 together with
its flange 62 is made of transparent material as in the foregoing
example, and an electric lamp 90 supplied with power by means of
lead wires 91 is installed therein. By the provision of this
electric lamp 90, the operator can adjust the knob 93 of the pinion
92 while visually inspecting the depth of insertion of the ear-rod
63 in the earhole of a patient. It will be needless to say that the
provision of such an illuminating means only to one of the ear-rods
is enough to serve the above purpose.
Now, in taking tomograms of the dentition, jawbones and other
objects in the head as in the foregoing, consideration should also
be given to the fact that such cavities present therein as the
mouth, the nostrills and the throad permit the penetration of too
much X-rays more than other part when these are radiated in certain
directions. The resultantly produced unevenness in the tone of a
radiographic film containing a series of tomograms prevent the
physician from obtaining correct diagnostic information therefrom.
This defect, however, can be eliminated by another device of the
invention newly introduced herein, in which filter means capable of
limiting the penetration of X-rays is installed on the side of an
X-ray tube and/or a radiographic film, thereby to obtain a tomogram
of uniform tone.
An example of such a device will now be described in detail with
reference to FIG. 15. A hood 94 made of transparent plastics
permitting the penetration of X-rays is supported by parts of the
above described head holding device so as to enclose the jawbones
95, spinal column 96, dentition and other parts of the head as in
the drawing. This hood 94 is attached with filter means 97 and 98
capable of limiting the penetration of X-rays radiated, and made,
for instance, of acrylic resin. Lacking these filter means 97 and
98, more of the X-rays radiated in the arrow marked directions over
widths A and B, for example, would reach a radiographic film
(disposed in front of the hood 94) than those radiated in other
directions, thus rendering the film portions impinged upon thereby
darker than the rest and leaving indistinct images of the jawbones
95 and so forth thereon. This undesirable darkening of parts of the
film can be successfully overcome by the device of the invention,
with its acrylic-resin-made filter means 97 and 98 attached to the
hood 94, either on its inside or outside surface and either closer
to the radiographic film or to the X-ray tube.
The filter means 97 attached to the open end of the hood 94, at the
back of the spinal column 96 in FIG. 15, may be made outwardly
openable by means of hinges 99. This helps a patient to move his
head into and out of the hood 94.
It is also noteworthy that the above described device is capable of
greatly reducing the high doses of X-rays administered hitherto to
a patient throughout a series of radiating operations (from 10 to
14 sheets of radiographic film for an adult) for the intraoral
radiographing examination of his dentition.
Although several specific examples of the various devices proposed
by the present invention have been shown and described in the
foregoing, it will be obvious that many modifications,
substitutions and changes thereof are possible. The invention,
therefore, is not intended to be restricted by the exact showing of
the drawings and the description thereof but is considered to
include other examples coming within the spirit of the
invention.
* * * * *