Apparatus and method for improving diagnostic X-rays

The present invention is especially suited for tomographic X-ray studies wherein dozens of exposures are required. A film cassette spacer having selected dimensions and having selected markings thereon is placed adjacent to the film cassette on a mechanically centering bucky tray in an X-ray machine. By use of the collimating means in the X-ray head, the number of exposures on the film can be maximized but still maintaining quality exposures for reading.

BACKGROUND OF THE INVENTION 
The present invention relates to x-ray machines, and, in particular, to 
x-ray machines having film trays that mechanically center the film 
cassette laterally upon the x-ray table. 
It is well known that many x-ray machines have examination tables with film 
cassette (bucky) trays therein that mechanically center the film cassettes 
of varying sizes on a longitudinal center line of the table. The bucky 
tray can move longitudinally on the table, but not laterally except for 
the purpose of inserting and removing film cassettes. Another feature is a 
collimating means located in the x-ray head. By use of the collimating 
means, the area of exposure may be adjusted to minimize unnecessary 
exposure to the patient where a reticle is projected onto the table. The 
size of the projected reticle is controlled by a diaphragm therein. The 
x-ray source is typically positioned on the longitudinal center line of 
the x-ray table. 
If one desired to take multiple exposures on one sheet of film, each 
exposure was always centered on the film because of the bucky tray 
centering device. Depending upon the film size and the collimated area, 2 
or 3 exposures could be placed on One sheet of film. It is clear from this 
standard practice that a significant amount of film area was wasted. 
Prior devices, for example, to maximize film usage are as follows: U.S. 
Pat. No. 1,219,965 discloses a partially enclosed tray having a 
rectangular opening therein. The film is moved within the tray to expose 
selected areas. This device has a fixed opening size therein. The opening 
is fixed within the tray and limited to a certain film size. U.S. Pat. No. 
2,545,899 discloses a partially enclosed film tray having movable openings 
to produce multiple exposures. The size of the openings are fixed as well 
as the distance from the center thus only a particular film size would 
produce optimum results. U.S. Pat. No. 3,955,656 discloses a film tray 
moveable under an aperture on an x-ray table. The tray is marked for a 
fixed size of film cassette and is able to produce multiple exposures by 
adjusting the cassette in the tray according to the guide lines thereon. 
These patents fail to address the problem of the present invention wherein 
film cassettes of various sizes are used in a buck tray having a fixed 
mechanically centering device therein. 
The need exists for an apparatus and method for being able to take multiple 
exposures of a size to be determined by the medical procedure and to 
optimize this size to the size of the film being used in a mechanically 
operated x-ray machine. 
SUMMARY OF THE INVENTION 
The present invention is directed at an apparatus and method to optimize 
film usage in an x-ray machine. 
An x-ray machine having a bucky tray, i.e., one where a single film 
cassette is mechanically centered, may use film cassettes of various 
sizes; the invention uses cassette spacers corresponding to various film 
cassette sizes which are placed into the bucky tray next to the film 
cassette and aligned therewith in the centering device. As a result 
thereof, the film cassette is shifted a predetermined distance away from 
the center line of the x-ray table. A plurality of markings on the 
cassette spacers allows one to position the exposures on the film 
accurately without the use of masks such as illustrated in U.S. Pat. Nos. 
2,545,899 and 3,050,656, for example. The use of the invention's masks 
would be applicable to x-ray machines without optical collimating means 
therein which projects a lit area onto the x-ray table. The film cassette 
and cassette spacers are moved for each exposure. After the required 
number of exposures are taken in one column, the cassette spacer is moved 
to the other side of the film cassette so as to shift the cassette. The 
next column of exposures are taken resulting in two columns of exposures 
rather than one which resulted from past techniques. If a collimator is 
not available on the x-ray head to localize and minimize the exposure, 
masks can be placed on the film cassette. 
It is therefore one object of the present invention to maximize the number 
of appropriate exposures on the film of any given size. 
Another object of the present invention is to provide an apparatus and 
method that saves film, reduces developing chemicals, reduces exam time, 
and reduces the time needed to examine the film. 
Another object of the present invention is to provide an apparatus and 
method for minimizing radiation exposure and improving the x-ray quality. 
Another object of the present invention is to provide an apparatus and 
method for use in tomographic studies. 
These and many other objects and advantages of the present invention will 
be readily apparent to one skilled in the pertinent art from the following 
detailed description of the invention and the related drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 3, a conventional x-ray machine 10 is shown. This machine 
10 may be a General Electric model, Siemens model, etc., having a 
mechanically operated cassette (bucky) tray 12 which normally centers a 
film cassette 16, FIG. 1, on a center line 18 of an x-ray table 20. An 
x-ray head 22 houses the source of x-rays, not shown, and, preferrably, a 
collimating means 24 which can be used to adjust the exposure size. 
Typically, the collimating means 24 includes a light source for projecting 
a reticle structure onto the table 20. Machine 10 may further include a 
drive means 26 for moving head 22 in an arcuate path for taking 
tomographic pictures, for example. It is understood that tomographic x-ray 
pictures are those that picture details at a particular area at a 
multitude of layers for determining the injury, for example, or defect. 
Because of this procedure, many pictures are required by the examining 
radiologist to study the problem in question. 
The time required to take these pictures by the radiologic technician can 
be extensive. The patient, as a result, may move and cause pictures to be 
blurry or marginal thus making the diagnosis more difficult resulting in 
additional pictures and exposure to x-rays. One would desire a technique 
to minimize the time required and still obtain quality x-ray pictures. 
Other benefits resulting from this invention will be evident. 
Referring to FIG. 1, the bucky tray 12 is shown in a top view as seen 
without the x-ray table top thereon. The bucky tray 12 has a platform 28 
with appropriate wheels 30 thereon which travel on tracks, not shown, in 
the table 20. In the platform 28 is a lateral slot 32 having projecting 
above the platform 28 a pair of movable clamps 34 that move in unison to 
or away from the center line 18 by action of a lever 36; the mechanical 
means connecting the lever 36 to the clamps 34 is not shown but considered 
conventional. 
The view of bucky tray 12 is that shown when the technician stands at a 
location 38, FIGS. 1 and 3 and looks down on the table 20, if the bucky 
tray 12 were visible from above. 
An x-ray film cassette spacer 40 is shown abutted against the film cassette 
16 on its left lateral side. The length, L, and the width, W, FIGS. 1 and 
2A, of the spacer 40 is determined by the size of the film and the 
cassette size as herein detailed. In practice the film size ranges from 
18.times.24 cm., 24.times.24 cm., 24.times.30 cm., and 30 .times.35 cm. 
The corresponding sizes for the spacer 40 are 8.57.times.26.67 cm., 
1.75.times.26.67 cm., 11.75.times.33.02 cm. and 13.65.times.38.10 cm. The 
spacer 40 is typically as long as film cassette the width is equal to 
one-half of the width of the film cassette. The length should be as close 
to the length of the film cassette 16 so that it can be quickly placed 
adjacent thereto and aligned thereon at the edges with the use of one's 
fingers. 
In practice, the film cassette width should be less than about two-thirds 
the maximum opening between the clamps 34 and the spacer 40 width, W, is 
about one-half the film cassette width. 
Referring to FIG. 2A, the spacer 40 is shown with guide marks on one side 
thereon. A guide line 4 indicates that there will be 4 pictures on a side 
with 8 total on each sheet of a size. 
In order to insure that each picture falls in the proper area, the bucky 
tray 12 is pulled out of the table 20 so that the spacer 40 is visible 
thereon. The x-ray head 22 is moved near to the operator's position and a 
collimating reticle 42, shown in outline in FIG. 2A is adjusted so that 
the reticle 42, for example, occupies one-quarter of the spacer 40 and is 
centered on the first guide line 4 by moving the combination of the spacer 
40 and the film cassette 12 horizontally. The bucky tray 12 is pushed into 
the x-ray table 20. Before this occurs the patient's body part is placed 
under the x-ray head 22. The size of the area to be exposed is determined 
by the technician which dictates how many pictures can be put on one 
sheet, if possible. After the exposure, the bucky tray 12 is pulled out 
and the spacer 40 and film cassette 16 are shift to the left, for example, 
till the next guide line 4 is centered on slot 32 or the center line 
running laterally in the bucky tray 12. This process is repeated 2 more 
times, for example. After this the spacer 40 is placed on the other 
lateral side of the film cassette 16 and the lever 36 is closed to center 
the combination as noted above. The first guide line 4 is then aligned 
with the slot 32, the exposure taken, and then the combination is shifted 
to the left and the above repeated until all 4 pictures are taken on this 
side. At this point there are 8 exposures on the sheet. 
Referring to FIG. 2B, another embodiment of the spacer 41 is shown having 
guide line markings on opposite sides to reduce confusion. 
These markings are used to allow the x-ray technician to accurately 
collimate and center the x-ray beam to the proper area on the film. The 
markings may be Of different colors in order to avoid confusion when doing 
exams. The lines may be made of permanent ink or paint put into etches in 
the spacer. Line A on side one of the spacer 41 would be a different color 
than line B. These lines are used to allow the technician to select the 
number of exposures desired. On side 1, the technician would initially 
center the reticle on the line A to place four exposures on one sheet. The 
reticle would be centered on line B to place two exposures on one sheet. 
On side 2 the reticle would be centered in the open area for placing six 
exposures on one sheet of film. Alternately on side 2, there could be 
three lines A and the reticle could be centered on these. The sides would 
be marked to indicate the number of exposures per sheet: 2 on one, 4 on 
one, 6 on one and 8 on one as appropriate. The number of lines on each 
spacer will depend on the number of exposures possible for that film size. 
It is seen from the above that there are several variables in this process 
to minimize film use. A skilled radiologic technician should be able to 
determine the area to be x-rayed, the number of exposures, and the size of 
film. 
The spacers 40 can be made from a stock 2.times.4.times.1/4 sheet of 
polyethylene, for example. The guide lines can be scribed thereon and 
appropriately colored and/or numbered. 
If the x-ray machine 10 does not have a high quality collimating means, 
lead masks covering one-half side of the film cassette and in contact 
thereon can be used. Additional masks having a quarter corner removed from 
a mask that covers the whole film cassette can be used to place four 
exposures on a sheet. These would be used in combination with the spacer 
40 to center the exposure on the appropriate area. 
This apparatus and method significantly reduce the cost of x-ray films in 
such procedures as in tomography studies. This results in fewer films 
without any loss in details or quality, saves films, film storage space, 
exam time and helps the radiologist study the films. 
With the GE x-ray machine, more than two exposures can be placed on 
18.times.24 cm., 24.times.24 cm., and 24.times.30 cm. film. On the 
30.times.35 cm. film, the spacer does not re-center the film so only two 
exposures can be made thereon. 
Examples of film and money savings when using the film spacers for 
tomographic studies are herein noted: 
Ankle Tomogram AP and Lat Tomos: 24.times.30 cm. film is used. Without the 
spacer 2 exposures were put on one film. Required 24 films costing $16.32. 
With the spacer 4 exposures were put on one film. Required 12 films 
costing $8.16. Savings are $8.16 per exam. 
TMJ Tomograph open and closed Laterals, both sides: 18.times.24 cm. film 
used. Without the spacer, put 2 to 3 exposures on one film. Required 36 
exposures using 12 films costing $5.04. With the spacer, 9 exposures were 
put on one film. Used 4 films costing $1.68. Savings are $3.36 per exam. 
Lumbar Spine Tomograms Ap and Laterals: 24.times.30 cm. film used. Without 
the spacer, one exposure per film. Required 30 exposures costing $20.40. 
With the spacer, two exposures per film. Required 15 films costing $10.20. 
Savings are $14.55 per exam. Using 30.times.35 cm. film, the savings per 
exam are $14.55. 
Generalized savings on multiple exams: 
10 Ankle tomos on 24.times.30 cm. film saved $81.60; 
10 TMJ tomos on 18.times.24 cm. film saved $33.60; 
10 Lumbar tomos on 24.times.30 cm. film saved $102.00; and 
10 Lumbar tomos on 30.times.35 cm. film saved $145.00. 
These savings do not reflect the time in manhours or the savings in 
chemicals used to develop the additional film as well as the wear and tear 
on the processors and x-ray tubes. 
Clearly, many modifications and variations of the present invention ar 
possible in light of the above teaching and it is therefore understood 
that within the inventive scope of the inventive concept, the invention 
may be practiced otherwise than specifically claimed.