U.S. patent number 3,652,852 [Application Number 04/812,688] was granted by the patent office on 1972-03-28 for method of superimposing the radiation emission from a radioactive tracer on an x-ray image.
This patent grant is currently assigned to Tokyo Shibaura Electric Co., Ltd.. Invention is credited to Tatsuo Miyazawa, Masashi Sato.
United States Patent |
3,652,852 |
Miyazawa , et al. |
March 28, 1972 |
METHOD OF SUPERIMPOSING THE RADIATION EMISSION FROM A RADIOACTIVE
TRACER ON AN X-RAY IMAGE
Abstract
A system for taking a radiograph of a foreground subject in
which a radioactive material is distributed on a film by an X-ray
radiographic apparatus having a spark chamber. The radiograph
consists of an X-ray transmission image of said subject and a
discharge image indicating the distribution of said radioactive
material. Said both images have the same scale and are superposed
on each other.
Inventors: |
Miyazawa; Tatsuo (Yokohama-shi,
JA), Sato; Masashi (Yokohama-shi, JA) |
Assignee: |
Tokyo Shibaura Electric Co.,
Ltd. (Kawasaki-shi, JA)
|
Family
ID: |
26359314 |
Appl.
No.: |
04/812,688 |
Filed: |
April 2, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Apr 5, 1968 [JA] |
|
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43/22138 |
Apr 5, 1968 [JA] |
|
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43/22141 |
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Current U.S.
Class: |
378/63;
250/363.01; 250/385.2; 378/175 |
Current CPC
Class: |
G03B
42/02 (20130101); A61B 6/4258 (20130101); G01T
1/2935 (20130101) |
Current International
Class: |
G01T
1/00 (20060101); G01T 1/29 (20060101); G03B
42/02 (20060101); G03b 041/16 () |
Field of
Search: |
;250/65,71.5S |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"Advances In Medical Scanning" by D. B. Sodee from Nucleonics, Vol.
22, No. 9, Sept., 1964, pages 47-51..
|
Primary Examiner: Lindquist; William F.
Claims
What we claim is:
1. A method of taking a radiograph of a portion of a body
comprising the steps of accumulating a radioactive tracer in a
section of said body portion, placing X-ray film in a position
enabling it to be responsive to radiation emanating from the body
portion, directing a collimated beam of X-rays through the body
portion onto the film, whereby an X-ray image of the body portion
is formed on the film, collimating energy from the accumulated
radioactive tracer into collimated rays directed parallel to and in
the same direction as the collimated X-rays directed onto the film,
placing a gaseous spark discharge chamber between the film and body
in the path of the collimated rays from the radioactive tracer,
whereby columnar light rays are derived from the spark chamber in
accordance with the distribution of radioactive tracer in the body
portion, exposing the film to the columnar light rays with the film
in the same position as when the X-ray image is formed thereon,
whereby the light ray and X-ray images are superimposed on the film
with the same scale, developing the film prior to exposing it to
the columnar light rays, then exposing the developed film to the
columnar light rays, and observing the developed film while it is
exposed to the columnar light rays.
2. The method of claim 1 further including the step of
photographing the developed film while it is exposed to the
columnar light rays.
Description
The present invention relates to radiographic methods and apparatus
and more particularly to methods and apparatus for taking a
radiograph of a foreground subject in which there is distributed a
radioisotope.
In the medical field, there is generally practiced a diagnostic
method which consists in introducing a minute amount of a specific
radioisotope into a living body by means of, for example,
intravenous injection or oral intake, and detecting the abnormal or
affected tissues of the specific parts, for example, internal
organs of a living body, utilizing the nature of such radioisotope
of selectively gathering in any particular affected area. The
aforementioned use of a radioisotope are required to define exactly
what part of a given internal organ has actually failed.
Heretofore, however, the position of the internal organ could only
be inferred from the particular bone structure related to said
organ. Since the size of the organ or the relative position of said
organ and associated bone structure varies with individuals, the
prior method failed accurately to locate the site of the organ, or
clearly to find what part of the organ became diseased.
The present invention provides a method for eliminating the
aforementioned drawbacks encountered with the conventional
radioisotope diagnostic process and unfailingly disclosing the
location of an affected organ, particularly what part of said organ
has developed an abnormal state.
The method of the present invention enables the image of a diseased
organ itself (or the image of its neighboring part if it is
impossible fully to obtain the image of the entire organ) and also
the image of the affected part of said organ (namely, an image
indicating the distribution of a radioisotope applied) to be
obtained, in a state superposed in the same size, using an X-ray
radiographic apparatus and a device involving a spark chamber.
Insofar as the present invention is concerned, where it is
impossible to obtain an image covering the whole of a given organ
as is the case with, for example, a living body whose tissues are
permeable to X-rays, the outline of the organ under consideration,
if defined substantially clearly by the image of its neighboring
bone structure, for example, may be deemed as an X-ray transmission
image of a foreground subject.
This invention can be more fully understood from the following
detailed description when taken in connection with the accompanying
drawings, in which:
FIG. 1 is a schematic cross section of an apparatus of the present
invention shown for the better understanding of the principle of
the invention and said apparatus;
FIG. 2 is a schematic diagram of a circuit for actuating a spark
chamber involved in the present apparatus;
FIG. 3 is a perspective view of the scene where a patient is
actually photographed using an X-ray image pickup apparatus
according to an embodiment of the invention;
FIGS. 4 to 10 are enlarged views of the various elements of the
image pickup apparatus of FIG. 3. FIG. 4 is a perspective view of a
support stand; FIG. 5 is a perspective view of a camera obscura;
FIG. 6 is a perspective view of the various parts of the camera
obscura shown in FIG. 5 where they are opened; FIG. 7 is a
perspective view of an assembly of an X-ray photographic film and a
cassette for holding said film; FIG. 8 is a perspective view of a
spark chamber; FIG. 9 is a perspective view of the spark chamber of
FIG. 8 when dismembered; and FIG. 10 is a perspective view of an
assembly of an X-ray generator and collimator; and
FIG. 11 is a quenching circuit for actuating the spark chamber of
the image pickup apparatus.
There will now be described an embodiment of the present invention
by reference to FIG. 1. Numeral of reference 11 denotes a camera
obscura or dark box made of radiation shielding material such as
lead, numeral 12 a bed, 13 a human body, and 14 a foreground
subject i.e., a portion of the body on which medical information is
desired such as an internal organ like a liver. Now let it be
assumed that there is selectively accumulated in the particular
effected tissue of the liver 14 a minute amount of a specified
radioisotope, for example, Au-198 which was injected as a tracer
into the human body 13 through the blood vessels. Numeral 15 is a
housing made of X-ray shielding material, such as lead which
contains an X-ray generator 16, for example, an X-ray tube. Numeral
17 is an X-ray collimator taking out X-rays 18 emitted in a
prescribed direction, which consists of, for example, a lead plate
perforated with a large number of through holes arranged in the
same direction. Numeral 19 is a cassette for holding an X-ray film
20 and exposure shutter 21. Between the foreground subject 14 and
cassette 19 is detachably fitted the later described spark chamber
22. Between the foreground subject 14 and spark chamber 22 is
detachably positioned another collimator 23 having substantially
the same construction as the first mentioned collimator 17. The
collimator 23 is used in taking out those rays 24 of radiation, for
example, gamma rays emitted by the radioisotope Au-198 distributed
in the foreground subject 14, which travel in a prescribed
direction, namely, parallel to the aforementioned X-rays 18.
As shown in FIG. 2, the spark chamber 22 comprises a first
electrode 25 prepared from a transparent conductive plate member,
for example, Nesa glass which consists of a glass plate and a thin
film of tin oxide coated on one surface thereof, or a metal plate
readily emitting secondary electrons when bombarded by radiation
and a second transparent conductive electrode 26 electrically
insulated by an insulating wall 27 formed of, for example, Teflon
or bakelite, thus forming a discharge chamber 28. In this discharge
chamber 28 is filled inert gas such as helium, neon or a mixture
thereof. Across both electrodes 25 and 26 of the spark chamber 22
is connected a DC source 30 through a quenching circuit 29. When
radiation 24 is introduced into the spark chamber from the side of
the first electrode 25 thereof, the electrons released from said
electrode 25 or those generated by ionization of the filled gas,
are accelerated by the electrical field defined by both electrodes
25 and 26, with the resultant occurrence of columnar discharges 31.
To describe more concretely, when the space between both electrodes
25 and 26 is 5 mm., the potential difference is 1.6 kv. and the
quenching circuit has a resistance of 10 to 20 M.OMEGA., then the
aforesaid column of discharges is 0.2 to 1.0 mm. in diameter. The
columnar discharges have a density distribution corresponding to
that of the incoming radiation flux, so that if light beams from
the columnar discharges are accumulated at a specified part for a
prescribed length of time, then it will be possible to observe from
the side of the second electrode 26 the distribution of radiation
in the foreground subject 14.
There will now be described the case of taking an X-ray radiograph
of a foreground subject 14 using the aforementioned radiographic
apparatus. First, the spark chamber 22 and collimator 23 are
removed from the apparatus. Then X-rays are released from the X-ray
generator 16, and allowed to be transmitted through the foreground
subject 14 via the collimator 17 to record the life-size image of
the foreground subject 14 on the film 20. (At this time, the
shutter 21 is of course opened.) With the foreground subject 14 and
film 20 kept in situ (in this case, they may be shifted in the
direction of the arrow 32 of FIG. 1 in their relative position
within a range of about 20 cm.), the spark chamber 22 and
collimator 23 are set in place as illustrated. When the spark
chamber 22 is actuated, namely, when there is impressed a
prescribed potential difference across the electrodes 25 and 26,
then only those rays of the radiations released from the foreground
subject 14 which travel in a prescribed direction, namely, parallel
to the X-rays 18 are introduced into the spark chamber 22.
Accordingly on the upper electrode 26 is formed the life-size
discharge image of the foreground subject 14 in accordance with the
distribution of a radioisotope therein. Then the shutter 21 is
operated to cause the discharge image to be superposed on the X-ray
image of the foreground subject 14 previously recorded in the film
20.
The sequential steps of the aforementioned procedure may be
reversed in the order, namely, the radiographing of a discharge
image may precede that of an X-ray image. Or the radiographing of
these images may be performed at the same time. In the case of
simultaneous radiographing it may be advisable, for example, to
coat the surface of the first electrode 25 of the spark chamber 22
with a material such as a film of lead capable of suitably
attenuating incoming X-rays or to select such material or thickness
of both electrodes 25 and 26 as to allow adequate amounts of
incoming X-rays to be transmitted therethrough.
As mentioned above, the present invention enables an X-ray
transmission image indicating the outline of a foreground subject
and a discharge image presenting the distribution of a radioisotope
in the foreground subject such as I-125, I-131, Tc-99m, Au-198,
Cr-51, Hg-203, Hg-197 or Cs-131 to be superposed in the ratio of
1:1. Accordingly, the present invention will render prominent
contributions not only to the aforementioned medical field, but
also in industrial applications such as non-destructive
testing.
Further the present invention allows X-ray image and discharge
image proportioned in the ratio of 1:1 to be observed either
directly by the naked eye, or by means of a camera, instead of
recording them in a single film.
To do this, an X-ray transmission image is first picked up in a
film held in a cassette. After being developed, the film is put
back to its original position in the pickup apparatus. Next the
spark chamber is actuated to cause the discharge image to be
projected on the developed film. The images thus superposed are
observed from above by the naked eye. If, in this case, there is
set a camera above the film, these superposed images may, of
course, be photographed.
There will now be concretely described by reference to FIGS. 3 to
10 an apparatus used in the image picking up method according to
the present invention. The same parts of these figures as those of
FIG. 1 are denoted by the same numerals.
FIG. 3 is a schematic perspective view of the scene where a patient
is diagnosed by the present apparatus. Numeral 40 denotes a support
pole capable of allowing a camera obscura or dark box 11 to be
vertically moved. Numeral 41 is a camera, and 42 is a circuit
connected to an X-ray source to generate X-rays. As shown in FIG.
4, the support pole 40 is fixed at the bottom end to a support base
43. On the support base 43 is mounted a housing 15 accommodating
the X-ray source 16 (FIG. 10). At the intermediate position of the
support pole 40 is fitted a holding frame 44, on which there is
mounted the camera obscura 11. As shown in FIG. 5, the dark box 11
is allowed freely to open at the top end face. This opening enables
the film placed therein to be observed by the naked eye or
photographed. The camera obscura 11 is further made separable into
two upper and lower parts 45 and 46 as shown in FIG. 6. Above the
lower part 46 is placed a cassette 19 to hold the film. Into the
cassette 19 are detachably fitted the X-ray film 20 and exposure
shutter 47 (FIG. 7). At the lower part 46 of the box 11 are
provided two drawers 48 and 49 one atop another. The upper drawer
48 holds the spark chamber 22 and the lower drawer 49 receives the
collimator 23. In front of the part of the box 11 containing these
drawers 48 and 49 is set a light shade so as to prevent external
light from entering the camera at this part. To the bottom of the
container 45 is fitted a flange perforated with screw holes so as
to fix the container by screwing the flange to the aforesaid
holding frame 44.
The first and second electrodes 25 and 26 of the spark chamber
(FIGS. 8 and 9) consist of a transparent glass plate bearing Nesa
coating. Between the electrodes 25 and 26 is interposed a frame 27
made of insulating material, part of said frame being provided with
inert gas outlets. Outside of the electrodes 25 and 26 are disposed
outer frames 51 and 52 respectively, which are screwed together to
assemble the spark chamber 22 as shown in FIG. 8.
FIG. 10 presents the housing 15 containing the X-ray source 16 and
collimator 17. The collimator 17 consists of a lead plate of a
prescribed width perforated with a large number of through holes
and is detachably fitted with respect to the housing 15 because it
is received in the drawer 53. The housing 15 is formed of X-ray
impermeable material, for example, lead. The X-ray source 16
contained therein may consist of a broad X-ray tube, or a plurality
of ordinary X-ray tubes arranged parallel. Further, it is possible
to form a slit above the X-ray tube and carry out scanning by
moving the slit and X-ray tube together in a crosswise
direction.
With the spark chamber involved in the image pickup apparatus of
the present invention, any circuit may be usable if it is of such a
type as is capable of actuating said chamber in a desired
condition. For illustration, there will now be concretely described
such circuit by reference to FIG. 11. The same parts of FIG. 11 as
those of the foregoing embodiment are denoted by the same numerals
and description thereof is omitted. The leakage resistance and
specific static capacity of the spark chamber 22 are designated by
R.sub.O and C.sub.O respectively. Between the electrodes 25 and 26
is connected a condenser C whose capacity C is so defined as to
have a relationship of C>>C.sub.O with respect to the
specific static capacity C.sub.O of the spark chamber. There is
serially connected an AC or DC source 30 through a resistor R.sub.T
between the electrodes 25 and 26, the first electrode 25 being
grounded. Parallel to said source 30 is connected a stabilizing
resistor R.sub.L. For illustration, when there was used a spark
chamber of C.sub.O = 2 .times. 10.sup.-.sup.10 F and R.sub.L = 3
M.OMEGA., then there resulted R.sub.T = 20 M.OMEGA. and C = 5
.times. 10.sup.-.sup.10 F.
* * * * *