CA1147069A - Shield device for controlling the dose of x-rays applied in an x-ray machine - Google Patents
Shield device for controlling the dose of x-rays applied in an x-ray machineInfo
- Publication number
- CA1147069A CA1147069A CA000368740A CA368740A CA1147069A CA 1147069 A CA1147069 A CA 1147069A CA 000368740 A CA000368740 A CA 000368740A CA 368740 A CA368740 A CA 368740A CA 1147069 A CA1147069 A CA 1147069A
- Authority
- CA
- Canada
- Prior art keywords
- shield
- rays
- cylinder
- shield device
- ray
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 210000002414 leg Anatomy 0.000 description 12
- 210000003423 ankle Anatomy 0.000 description 7
- 244000309466 calf Species 0.000 description 3
- 210000004072 lung Anatomy 0.000 description 3
- 210000000689 upper leg Anatomy 0.000 description 2
- 210000003484 anatomy Anatomy 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 210000003625 skull Anatomy 0.000 description 1
- 210000004872 soft tissue Anatomy 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
- G21K1/04—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/06—Diaphragms
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
- G21K1/04—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers
- G21K1/043—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators using variable diaphragms, shutters, choppers changing time structure of beams by mechanical means, e.g. choppers, spinning filter wheels
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Medical Informatics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Molecular Biology (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Radiology & Medical Imaging (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Apparatus For Radiation Diagnosis (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A shield device for use with an X-ray machine. The shield device comprises a shaped shield preferably mounted with a transparent cylinder which is rotated about a longitudinal axis transverse to the path of X-rays produced by the machine to block out these X-rays for a longer period of time in some areas of the subject being X-rayed than in other areas during the time the X-ray picture is taken. This shield device can advantageously be used for obtaining differential X-ray exposure in one single shot.
A shield device for use with an X-ray machine. The shield device comprises a shaped shield preferably mounted with a transparent cylinder which is rotated about a longitudinal axis transverse to the path of X-rays produced by the machine to block out these X-rays for a longer period of time in some areas of the subject being X-rayed than in other areas during the time the X-ray picture is taken. This shield device can advantageously be used for obtaining differential X-ray exposure in one single shot.
Description
~7~69 The p~esent invention relates a shield device for use with an X-ray machine to control the dose of X-rays applied to a patient.
In taking X-rays~ particularly of people, a problem exists due to the variations in thickness and/or density of the different anatomical parts. The thighs or hips of a person by way of example, are thicker than his calves or ankles. Thus, in order to obtain a fairly uniform X-ray picture of a person, from the waist down, a higher dose of X-rays should be applied to the hip-thigh area than to the calf-ankle area. If this is not done, and a sufficient dose of X-rays is applied to obtain a suitable picture of the hip and thigh area, this same dose overexposes the calf and ankle area. Similarly, if a dose of X-rays is applied to obtain a suitable picture of the calf and ankle area, then this same dose underexposes the hip and thi~h area.
To overcome the above problem of providing the approximate proper dose of X-rays to areas requirin~ different doses, it is known to employ filters which are thicker in those areas requiring a small dose of X-rays and thinner in those areas requiring a larger dose of X-rays. The filter is interpo-sed between the source of X-rays and the subject being X-rayed.
Filters however reduce the power of the X-rays pass-ing through them so that more power is required to take the same picture than the power required without a filter.
Thus it is an object of the present invention to provide an improved shield for use with an X-ray machine, which shield can control the dose of X-rays applied to hy the mach.ine in different areas o~ the picture without affecting the power of the X-rays.
In accordance with the present invention this object ~._ ~L7~69 is achieved with a shield especially designed and positioned to intercept the X-rays for longer or shorter periods in different areas during the taking of the picture, but not for the whole period of time necessary for taking this picture.
Each area of the subject being X~rayed, is exposed to full power X-rays. However~ owing to the shield, the areas that require smaller dose, receive these full power X-rays for a shorter portion of the full period of time required to take the picture while the other areas that require larger dose of X-rays, receive the full power X-rays for a longer portion of the full period of time required to take the picture.
To ensure this differential exposure, the shield is placed through the path of the X-rays and rotated about an axis which is generally transverse to the direction of travel of the X-rays to cut out some of said X~rays for different portions of the period of time necessary for taking the picture. The shield is preferably shaped to intercept X-rays for a longer period in some areas than in others depending on the required doses. A plurality of differently shaped shields can be provided to suit different picture taking situations.
The invention is particularly directed toward a shield device for use with an X-ray machine comprising an X-ray shield and means for rotating the shield about a longitudinal axis transverse to the path of the X-rays produced by the machine to intercept some of these X-rays in taking an X-ray picture of a subject for part of the time period during which the X-rays are produced.
The shield preferably has a uniform thickness and is shaped to intercept more X-rays in one area of the subject than in another.
Preferably, the shield is mounted within a transparent cylinder rotatable about its longitudinal axis, said cylinder
In taking X-rays~ particularly of people, a problem exists due to the variations in thickness and/or density of the different anatomical parts. The thighs or hips of a person by way of example, are thicker than his calves or ankles. Thus, in order to obtain a fairly uniform X-ray picture of a person, from the waist down, a higher dose of X-rays should be applied to the hip-thigh area than to the calf-ankle area. If this is not done, and a sufficient dose of X-rays is applied to obtain a suitable picture of the hip and thigh area, this same dose overexposes the calf and ankle area. Similarly, if a dose of X-rays is applied to obtain a suitable picture of the calf and ankle area, then this same dose underexposes the hip and thi~h area.
To overcome the above problem of providing the approximate proper dose of X-rays to areas requirin~ different doses, it is known to employ filters which are thicker in those areas requiring a small dose of X-rays and thinner in those areas requiring a larger dose of X-rays. The filter is interpo-sed between the source of X-rays and the subject being X-rayed.
Filters however reduce the power of the X-rays pass-ing through them so that more power is required to take the same picture than the power required without a filter.
Thus it is an object of the present invention to provide an improved shield for use with an X-ray machine, which shield can control the dose of X-rays applied to hy the mach.ine in different areas o~ the picture without affecting the power of the X-rays.
In accordance with the present invention this object ~._ ~L7~69 is achieved with a shield especially designed and positioned to intercept the X-rays for longer or shorter periods in different areas during the taking of the picture, but not for the whole period of time necessary for taking this picture.
Each area of the subject being X~rayed, is exposed to full power X-rays. However~ owing to the shield, the areas that require smaller dose, receive these full power X-rays for a shorter portion of the full period of time required to take the picture while the other areas that require larger dose of X-rays, receive the full power X-rays for a longer portion of the full period of time required to take the picture.
To ensure this differential exposure, the shield is placed through the path of the X-rays and rotated about an axis which is generally transverse to the direction of travel of the X-rays to cut out some of said X~rays for different portions of the period of time necessary for taking the picture. The shield is preferably shaped to intercept X-rays for a longer period in some areas than in others depending on the required doses. A plurality of differently shaped shields can be provided to suit different picture taking situations.
The invention is particularly directed toward a shield device for use with an X-ray machine comprising an X-ray shield and means for rotating the shield about a longitudinal axis transverse to the path of the X-rays produced by the machine to intercept some of these X-rays in taking an X-ray picture of a subject for part of the time period during which the X-rays are produced.
The shield preferably has a uniform thickness and is shaped to intercept more X-rays in one area of the subject than in another.
Preferably, the shield is mounted within a transparent cylinder rotatable about its longitudinal axis, said cylinder
- 2 -I
~47~9 being positioned -transverse to the path oE the X-rays, and positively connected -to the rotating means of the device so as to be rotated about its longitudinal axis by said rotating means during operation of the X-ray machine, said rota-tion of the cylinder ensuring rotation of the shield transverse to the path of the X-rays.
Some preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings in which:
Fig. 1 is a perspective, partially ex loded, view of a shield device;
Fig. 2 is an elevation view, in partial section, of the shield device shown in Fig. l;
Fig. 3 is an elevation view of another embodiment of shield cylinder that can be used in the shield device of Fig. l;
Fig. 4 is an elevation view of a further embodiment of shield cylinder that can be used in the shield device of Fig.
/
Figs. 5, 6 and 7 are perspective views schematically showing the shield cylinders shown in Figs. 2,3, and 4 respectively in use;
Fig. 8 is a perspective view of still another embodiment of shield cylinder tha t can be used in a shield device; and Figs. 9a, 9b and 9c are top plan views schematically showing three different combinations of two shield cylinders in use~ respectively.
The shield device 1 as shown in Figs. 1 and 2 has a supporting enclosure 3. The enclosure 3 has side walls 5, a bottom walI 7 and a top wall 9. The top wall 9 of the enclosure can be made smaller than the bottom wall 7. The upper portion of the side walls 5 can then be sloped inwardly to connect the smaller top wall9 with the bottom wall 7 as shown, with the ~7~9 top wall centered with respect to the bottom wall. A large central opening or port 11 is provided in the bottom wall 7 and a smaller central opening or port 13 is provided in the top wall 9. An adapter plate 15 is provided outside the enclosure
~47~9 being positioned -transverse to the path oE the X-rays, and positively connected -to the rotating means of the device so as to be rotated about its longitudinal axis by said rotating means during operation of the X-ray machine, said rota-tion of the cylinder ensuring rotation of the shield transverse to the path of the X-rays.
Some preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings in which:
Fig. 1 is a perspective, partially ex loded, view of a shield device;
Fig. 2 is an elevation view, in partial section, of the shield device shown in Fig. l;
Fig. 3 is an elevation view of another embodiment of shield cylinder that can be used in the shield device of Fig. l;
Fig. 4 is an elevation view of a further embodiment of shield cylinder that can be used in the shield device of Fig.
/
Figs. 5, 6 and 7 are perspective views schematically showing the shield cylinders shown in Figs. 2,3, and 4 respectively in use;
Fig. 8 is a perspective view of still another embodiment of shield cylinder tha t can be used in a shield device; and Figs. 9a, 9b and 9c are top plan views schematically showing three different combinations of two shield cylinders in use~ respectively.
The shield device 1 as shown in Figs. 1 and 2 has a supporting enclosure 3. The enclosure 3 has side walls 5, a bottom walI 7 and a top wall 9. The top wall 9 of the enclosure can be made smaller than the bottom wall 7. The upper portion of the side walls 5 can then be sloped inwardly to connect the smaller top wall9 with the bottom wall 7 as shown, with the ~7~9 top wall centered with respect to the bottom wall. A large central opening or port 11 is provided in the bottom wall 7 and a smaller central opening or port 13 is provided in the top wall 9. An adapter plate 15 is provided outside the enclosure
3 adjacent the top wall 9. The adapter plate lS has a rectangu-lar shape with a central opening or port 17 therein adapted to be aligned with the opening 13 in the top wall 9 when the plate 15 is fastened to the enclosure 3.
A U-shaped mounting bracket 19 is provided within the enclosure 3 adjacent the top wall 9. The mounting bracket 19 has a rectangular shaped base 21 with a narrow central opening or port 23 therein, and side legs 25 and 27 at the ends of the base 21. Threaded mounting holes 29 are provided at the corners of the bracket base 21. Threaded screws 31, which pass through holes 33 in the adapter plate 15, and through holes (not shown) in the top wall 9 of the enclosure 3 securely join the plate 15 and bracket 19 together with the top wall between them, and with their ports 13, 17 and 23 generally aligned.
The adapter plate 15 is used to connect the device 1 :
to an X-ray machine, with the ports 11 and 13 in the enclosure 3, the port 17 in -the plate 15, and the port ~3 in the bracket 19 all aligned with the source S, or outlet, of X-rays in the X-ray machine. The ports are shown generally elongated and the device 1 is generally mounted with the long direction of the ports aligned with the long direction of the X-ray source S, if it has a long direction. However means could be provided between the adaptor plate 15 and the X-ray machine to rotate the device through 90 to move the ports transversely to the long direction of the X~ray source, and thus to narrow the field of exposure, if desirable.
Mounted between the legs 25 and 27 of the bracket 19 ~ 4 -~7~6g is a shield cylinder 35. The shield cylinder 35 has a transpa-rent tubular body 37. One end of the body 37 is closed with a first cap 39 fixed to the body. A conical mounting depression 41 is provided in the center of the outer surface of the firs-t closure cap 39. The other end of the tubular body 37 is closed with a second closure cap 43 fixed to the body. A
pulley 45 is fixed to the outer surface of the cap 43.
The outer surface of the pulley 45 which is centrally located on the surface of the cap 43,has a conical mounting depression 47, similar to the depression 41 in first cap 39 formed in its center.
The shield cylinder 35 is mounted for rotation about its longitudinal aY~is between the legs 25 and 27 of the bracket 19 using the mounting depressions 41 and 47. A first, threaded, mounting pin 51 is screwed through a mounting hole 53 in one side leg 25 of the mounting bracket 19. The front end of the pin 51 enters the depression 41 in the first closure cap 39 of the cylinder 35, which is located closely adjacent to the bracket leg 25. A nut 55 is threaded onto the pin 51 tight a~ainst the outside surface of the leg 25 to lock the pin Sl in place. A set screw 57 can be threaded through a hole in the nut 55 to lock the nut 55 tight onto the pin 51. A
second threaded mounting pin 59 is screwed through a mounting hole 61 in the other side leg 27 of the mounting bracket. The front end of this second mounting pin 59 enters the mounting depression 47 on the outer surface of the pulley 45 at the other end of the cylinder 35. The pulley 45 is located closely adjacent the side leg 27. The two mounting pins 51 and 59 are aligned and an imaginery line 63 joining them is generally parallel to the base 21 of bracket 19. A lock nut 65 and a set screw 67 lock the mounting pin 59 in pl~ce.
It will be seen that the shield cylinder 35 is ~73~
rotatably mounted in bracket 19 between the pins 51 and 59.
When mounted, the cylinder 35 is interposed between the bottom opening 11 in enclosure 3 and the top opening 13.
Suitable means are provided for rotating the shield cylinder 35. These means comprise a motor 71 fixed to a plate 73 movably mounted on the outer surface of the bracket leg 27.
The p]ate 73 can move up and down relative to the bracket leg 27, via slots in the plate (not shown) and bolts 75 passing through the slots to connect to the bracket leg 27. When the bolts 75 are loosened, the plate 73 can be adjusted relative to the leg 27. Once adjusted, the bolts 75 are tightened to lock the plate 73 in place. An elongated opening (not shown) can be provided in the central upper portion of the plate 73 through which the second mounting pin 59, nut 65 and set screw 67 project so as to avoid interfering with the movement of the plate 73 during its adjustment. The shaft 77 of the motor 71 projects through an opening in the plate 73 and a pulley 79 is fixed to the end of the shaft 77. The pulley 79 is aligned with the pulley 45 on the shield cylinder 35 and a belt 81 connects the two pulleys 79 and 45 together. The belt 81 is tightened by adjusting the plate 73. Power is provided to the motor 71 by a cord 83 from a suitable external power source.
In accordance with the invention, a shield 91 is mow~ted on the shield cylinder 35. Preferably the shield 91 is fixed to one end of the closure cap 43 and projects therefrom into the transparent tubular body 37. Preferably also, the shield 91 is curved to follow close to the inner surface of the body 37. The shield 91 is made of suitable material, such as lead, which blocks out X-rays. The shield 91 is shaped to block out X-rays in selected areas, or in a selected pattern, during a portion of the time the X~ray machine, to which the device is attached, is taking a picture. For example, the shield 91 shown ~ 6 -~7~9 in Fiys. 1 ancl 2 tape~s from a wide portion 93 at one end adjacent cap 43, t.O a narrow portion 95 at its other end located slightly past the middle of the tube 37 along a spiral axis.
This shield is designed for taking a picture of the lower body por-tion oE a person where less X-ray dosage is required at the ankles than at the hips to obtain a relatively uniform picture. The wide portion 93 of the shield intercepts X-rays for a relatively ]ong portion of the total period of time during which the picture is taken, in the area of the ankles while the narrow portion 95 of the shield intercepts X-rays for a relatively short portion of the total period of time in the area of the hips.
In operation, the shaped shield 91 is rapidly rotated during the taking of the X-ray picture by rotation of the cylinder 35 via the motor 71 and belt 81. As the shield 91 rapidly rotates it blocks out some of the X-rays generated during the taking of the picture with more of the X-rays being blocked out by the wide end of the shield at the ankle area than are blocked out by the narrow end of the shield at the hip area. Indeed, the ankle area is exposed to full power X-rays for a shorter period of ~ime than is the hip area.
Different shaped shields can be provided depending on the subject to the X-rayed. Thus, for example, the curved, spiral shaped, triangular shield 91 shown in Figs. 1 and 2 can be used in orthopedy for taking a partial or even complete picture of the skeleton of an adult or a child with a differen-tial X-ray exposure in one single shot, as is schematically illustrated in Fig. 5. Another curved, vial-shaped shield 91' as shown in Fig. 3 can be used in a cylinder 35' for taking X-ray picture of the skull and face of a person in orthodonty as is schematicall~ illustrated in Fig. 6. The shield 91~
which has a symetrical, large surface area, blocks out a large - 7 ~
~7~169 number of the X-rays o~ex the side-face o the person~s head for a relatively long period of time when the shield is rotated, and -thus allows taking of a picture of both the brain-pan and the soft tissue of the patient's face. The same shield 91' can also be used for taking a X-ray picture of a child, such a picture requiring much less exposure to full power X-rays than that of an adult. The cylinder 35' can easily replace the existing cylinder 35 in the device by loosening the drive belt 81 and the mounting pins 51 and 59.
In a similar manner, an additional shield made of two recessed, cylindrical end portions 91" as shown in Fig. 4 can be used in a cylinder 35" for taking X-ray picture of the lungs, spinal column and heart of a person in one single shot, as is schematically illustrated in Fig. 7. Indeed, the recessed parts of the shield 91" that are located at both ends of the cylinder 35" respectively, block out a large number of X-rays laterally over the lungs of the person for a relatively long period of time when the shield device is rotated and thus allow immediate "compensation" of the picture areas correspond-ing to the spinal column, heart and lungs which must in practice be each exposed to a different X-ray power to be seen on a X-ray pic~ure.
In each of the above described and illustrated shield devices, the shield 91r 91' or 91" is curved to follow close the inner surface of the cylinder 35, 35' or 35"
respectively. This feature however is not critical. Indeed, use could also be made of one or more flat, shutter-shaped shield 91"' fixed into a cylinder or cylindrical support 35"' either radially or not, as is shown in Fig. 8, with the same advantageous results as above.
It should be noted that the present invention is not restricted to the above described shaped shields but includes anyiother kind of shields mounted in rotation about ~7~6~
a longitudinal axis transverse to the path o:E the X-rays, with or without the presence of a supporting cylinder. It should also be noted that the present invention is not restric-ted in scope to the use of one shield only but includes any combination of two or more shields mounted in "para~llel" or in "series" with respect to the path of the X-rays as is schemati-cally illustrated in Figs. 9a, 9b and 9c.
The shields used in such combinations may have shap~s different from each other or identical to each other depending on the required pattern of differential exposure and may be positioned in parallel or perpendical relationship with respect to each other, as is shown in Figs. 9a, 9b and 9c.
.~ .
-
A U-shaped mounting bracket 19 is provided within the enclosure 3 adjacent the top wall 9. The mounting bracket 19 has a rectangular shaped base 21 with a narrow central opening or port 23 therein, and side legs 25 and 27 at the ends of the base 21. Threaded mounting holes 29 are provided at the corners of the bracket base 21. Threaded screws 31, which pass through holes 33 in the adapter plate 15, and through holes (not shown) in the top wall 9 of the enclosure 3 securely join the plate 15 and bracket 19 together with the top wall between them, and with their ports 13, 17 and 23 generally aligned.
The adapter plate 15 is used to connect the device 1 :
to an X-ray machine, with the ports 11 and 13 in the enclosure 3, the port 17 in -the plate 15, and the port ~3 in the bracket 19 all aligned with the source S, or outlet, of X-rays in the X-ray machine. The ports are shown generally elongated and the device 1 is generally mounted with the long direction of the ports aligned with the long direction of the X-ray source S, if it has a long direction. However means could be provided between the adaptor plate 15 and the X-ray machine to rotate the device through 90 to move the ports transversely to the long direction of the X~ray source, and thus to narrow the field of exposure, if desirable.
Mounted between the legs 25 and 27 of the bracket 19 ~ 4 -~7~6g is a shield cylinder 35. The shield cylinder 35 has a transpa-rent tubular body 37. One end of the body 37 is closed with a first cap 39 fixed to the body. A conical mounting depression 41 is provided in the center of the outer surface of the firs-t closure cap 39. The other end of the tubular body 37 is closed with a second closure cap 43 fixed to the body. A
pulley 45 is fixed to the outer surface of the cap 43.
The outer surface of the pulley 45 which is centrally located on the surface of the cap 43,has a conical mounting depression 47, similar to the depression 41 in first cap 39 formed in its center.
The shield cylinder 35 is mounted for rotation about its longitudinal aY~is between the legs 25 and 27 of the bracket 19 using the mounting depressions 41 and 47. A first, threaded, mounting pin 51 is screwed through a mounting hole 53 in one side leg 25 of the mounting bracket 19. The front end of the pin 51 enters the depression 41 in the first closure cap 39 of the cylinder 35, which is located closely adjacent to the bracket leg 25. A nut 55 is threaded onto the pin 51 tight a~ainst the outside surface of the leg 25 to lock the pin Sl in place. A set screw 57 can be threaded through a hole in the nut 55 to lock the nut 55 tight onto the pin 51. A
second threaded mounting pin 59 is screwed through a mounting hole 61 in the other side leg 27 of the mounting bracket. The front end of this second mounting pin 59 enters the mounting depression 47 on the outer surface of the pulley 45 at the other end of the cylinder 35. The pulley 45 is located closely adjacent the side leg 27. The two mounting pins 51 and 59 are aligned and an imaginery line 63 joining them is generally parallel to the base 21 of bracket 19. A lock nut 65 and a set screw 67 lock the mounting pin 59 in pl~ce.
It will be seen that the shield cylinder 35 is ~73~
rotatably mounted in bracket 19 between the pins 51 and 59.
When mounted, the cylinder 35 is interposed between the bottom opening 11 in enclosure 3 and the top opening 13.
Suitable means are provided for rotating the shield cylinder 35. These means comprise a motor 71 fixed to a plate 73 movably mounted on the outer surface of the bracket leg 27.
The p]ate 73 can move up and down relative to the bracket leg 27, via slots in the plate (not shown) and bolts 75 passing through the slots to connect to the bracket leg 27. When the bolts 75 are loosened, the plate 73 can be adjusted relative to the leg 27. Once adjusted, the bolts 75 are tightened to lock the plate 73 in place. An elongated opening (not shown) can be provided in the central upper portion of the plate 73 through which the second mounting pin 59, nut 65 and set screw 67 project so as to avoid interfering with the movement of the plate 73 during its adjustment. The shaft 77 of the motor 71 projects through an opening in the plate 73 and a pulley 79 is fixed to the end of the shaft 77. The pulley 79 is aligned with the pulley 45 on the shield cylinder 35 and a belt 81 connects the two pulleys 79 and 45 together. The belt 81 is tightened by adjusting the plate 73. Power is provided to the motor 71 by a cord 83 from a suitable external power source.
In accordance with the invention, a shield 91 is mow~ted on the shield cylinder 35. Preferably the shield 91 is fixed to one end of the closure cap 43 and projects therefrom into the transparent tubular body 37. Preferably also, the shield 91 is curved to follow close to the inner surface of the body 37. The shield 91 is made of suitable material, such as lead, which blocks out X-rays. The shield 91 is shaped to block out X-rays in selected areas, or in a selected pattern, during a portion of the time the X~ray machine, to which the device is attached, is taking a picture. For example, the shield 91 shown ~ 6 -~7~9 in Fiys. 1 ancl 2 tape~s from a wide portion 93 at one end adjacent cap 43, t.O a narrow portion 95 at its other end located slightly past the middle of the tube 37 along a spiral axis.
This shield is designed for taking a picture of the lower body por-tion oE a person where less X-ray dosage is required at the ankles than at the hips to obtain a relatively uniform picture. The wide portion 93 of the shield intercepts X-rays for a relatively ]ong portion of the total period of time during which the picture is taken, in the area of the ankles while the narrow portion 95 of the shield intercepts X-rays for a relatively short portion of the total period of time in the area of the hips.
In operation, the shaped shield 91 is rapidly rotated during the taking of the X-ray picture by rotation of the cylinder 35 via the motor 71 and belt 81. As the shield 91 rapidly rotates it blocks out some of the X-rays generated during the taking of the picture with more of the X-rays being blocked out by the wide end of the shield at the ankle area than are blocked out by the narrow end of the shield at the hip area. Indeed, the ankle area is exposed to full power X-rays for a shorter period of ~ime than is the hip area.
Different shaped shields can be provided depending on the subject to the X-rayed. Thus, for example, the curved, spiral shaped, triangular shield 91 shown in Figs. 1 and 2 can be used in orthopedy for taking a partial or even complete picture of the skeleton of an adult or a child with a differen-tial X-ray exposure in one single shot, as is schematically illustrated in Fig. 5. Another curved, vial-shaped shield 91' as shown in Fig. 3 can be used in a cylinder 35' for taking X-ray picture of the skull and face of a person in orthodonty as is schematicall~ illustrated in Fig. 6. The shield 91~
which has a symetrical, large surface area, blocks out a large - 7 ~
~7~169 number of the X-rays o~ex the side-face o the person~s head for a relatively long period of time when the shield is rotated, and -thus allows taking of a picture of both the brain-pan and the soft tissue of the patient's face. The same shield 91' can also be used for taking a X-ray picture of a child, such a picture requiring much less exposure to full power X-rays than that of an adult. The cylinder 35' can easily replace the existing cylinder 35 in the device by loosening the drive belt 81 and the mounting pins 51 and 59.
In a similar manner, an additional shield made of two recessed, cylindrical end portions 91" as shown in Fig. 4 can be used in a cylinder 35" for taking X-ray picture of the lungs, spinal column and heart of a person in one single shot, as is schematically illustrated in Fig. 7. Indeed, the recessed parts of the shield 91" that are located at both ends of the cylinder 35" respectively, block out a large number of X-rays laterally over the lungs of the person for a relatively long period of time when the shield device is rotated and thus allow immediate "compensation" of the picture areas correspond-ing to the spinal column, heart and lungs which must in practice be each exposed to a different X-ray power to be seen on a X-ray pic~ure.
In each of the above described and illustrated shield devices, the shield 91r 91' or 91" is curved to follow close the inner surface of the cylinder 35, 35' or 35"
respectively. This feature however is not critical. Indeed, use could also be made of one or more flat, shutter-shaped shield 91"' fixed into a cylinder or cylindrical support 35"' either radially or not, as is shown in Fig. 8, with the same advantageous results as above.
It should be noted that the present invention is not restricted to the above described shaped shields but includes anyiother kind of shields mounted in rotation about ~7~6~
a longitudinal axis transverse to the path o:E the X-rays, with or without the presence of a supporting cylinder. It should also be noted that the present invention is not restric-ted in scope to the use of one shield only but includes any combination of two or more shields mounted in "para~llel" or in "series" with respect to the path of the X-rays as is schemati-cally illustrated in Figs. 9a, 9b and 9c.
The shields used in such combinations may have shap~s different from each other or identical to each other depending on the required pattern of differential exposure and may be positioned in parallel or perpendical relationship with respect to each other, as is shown in Figs. 9a, 9b and 9c.
.~ .
-
Claims (8)
1. A shield device for use with an X-ray machine comprising an X-ray shield and means for rotating said shield about a longitudinal axis transverse to the path of the X-rays produced by the machine to intercept some of said X-rays in taking an X-ray picture of a subject for a portion of the period of time during which said X-rays are produced.
2. A shield device as claimed in claim 1, wherein the shield has a substantially uniform thickness and is shaped to intercept more X-rays in one area of the subject than in another.
3. A shield device as claimed in claim 2, wherein the shield is mounted within a transparent cylinder rotatable about its longitudinal axis, said cylinder being positioned trans-verse to the path of the X-rays and positively connected to the rotating means of the device so as to be rotated about its longitudinal axis by said rotating means during operation of the X-ray machine,said rotation of the cylinder ensuring rotation of the shield transverse to the path of the X-rays.
4. A shield device as claimed in claim 3, including means for removably attaching the transparent cylinder to the X-ray machine.
5. A shield device as claimed in claim 4, wherein the shield mounted within the transparent cylinder is curved to lie adjacent the surface of said cylinder.
6. A shield device as claimed in claim 5, wherein the shield mounted within the transparent cylinder extends radially inwards said cylinder.
7. A shield device as claimed in claim 4, 5 or 6, including a plurality of shield-mounting cylinders, each cylinder having a shield shaped different from the other shields to intercept X-rays in a different pattern from said other shields.
8. A shield device as claimed in claim 2 or 4, wherein the shield is in the shape of a curved, spiral-shaped triangle, a curved vial or a set of two recessed, end-portion cylinders.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000368740A CA1147069A (en) | 1981-01-16 | 1981-01-16 | Shield device for controlling the dose of x-rays applied in an x-ray machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000368740A CA1147069A (en) | 1981-01-16 | 1981-01-16 | Shield device for controlling the dose of x-rays applied in an x-ray machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1147069A true CA1147069A (en) | 1983-05-24 |
Family
ID=4118945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368740A Expired CA1147069A (en) | 1981-01-16 | 1981-01-16 | Shield device for controlling the dose of x-rays applied in an x-ray machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1147069A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0290165A1 (en) * | 1987-05-07 | 1988-11-09 | Picker International, Inc. | Radiography apparatus |
| US4905268A (en) * | 1985-10-25 | 1990-02-27 | Picker International, Inc. | Adjustable off-focal aperture for x-ray tubes |
| EP0373285A1 (en) * | 1988-12-16 | 1990-06-20 | Siemens Aktiengesellschaft | Diaphragm for an X-ray diagnostic apparatus |
-
1981
- 1981-01-16 CA CA000368740A patent/CA1147069A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4905268A (en) * | 1985-10-25 | 1990-02-27 | Picker International, Inc. | Adjustable off-focal aperture for x-ray tubes |
| EP0290165A1 (en) * | 1987-05-07 | 1988-11-09 | Picker International, Inc. | Radiography apparatus |
| EP0373285A1 (en) * | 1988-12-16 | 1990-06-20 | Siemens Aktiengesellschaft | Diaphragm for an X-ray diagnostic apparatus |
| US4947417A (en) * | 1988-12-16 | 1990-08-07 | The University Of Virginia Alumni Patents Foundation | Adjusting arrangement for radio-diagnostic equipment |
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| MKEX | Expiry |