US2695964A

US2695964A - X-ray apparatus

Info

Publication number: US2695964A
Application number: US183799A
Authority: US
Inventors: Paul F Schepker
Original assignee: KELEKET X RAY CORP
Current assignee: KELEKET X RAY CORP; KELEKET X-RAY Corp
Priority date: 1950-09-08
Filing date: 1950-09-08
Publication date: 1954-11-30
Anticipated expiration: 1971-11-30

Description

Nov. 3o, 1954 P, F, SHEPKER l.2,695,964

X-RAY APPARATUS Filed Sept. 8, 1950 I N VEN TOR.

BY PAUL E SCHEPKEK 60 @WMM-JM ATTORNEYS' VUnited States Patent O X-RAY APPARATUS Paul F. Schepker, South Fort Mitchell, Ky., assignor to Keleket X-Ray Corporation, a corporation of Ohio Application september s, 195o, serial No. 183,799

Claims. (Cl. Z50-62) This inventionk relates to X-ray apparatus and more particularly to the timing of exposures t'o X-ray radiation.

The invention has particular relation to the timing of X-ray exposures by means of photoelectric apparatus in which a uorescent screen is positioned in the path of the X-ray beam after it has passed through the subject, and a phototube is mounted in position to' receive the light from the screen and is connected in a control circuit which acts to terminate the exposure at the proper instant in accordance with the measured response of the phototube. This control circuit is readily adjustable in accordance with the density of the tissues or parts of the body being exposed, and itis particularly useful in radiography to assure that suiiicient radiation will pass through the subject for adequate exposure of the ilm.

Photoelectric timing apparatus of this character is disclosed in Morgan and Hodges Patents 2,401,288 and 2,401,289 issued May 28, 1946, and it has proved satisfactory for many applications. However, its use has been to some extent circumscribed by the physical limitations of space imposed by the construction of conventional pieces of X-ray equipment which provide insufficient clearance for the screen and phototube, and it has accordingly been ditiicult if not impossible in some cases to employ such timing apparatus on existing equipment. Thus in an X-ray table intended for both iiuoroscopy and radiography, the tube carriage for fluoroscopy includes shutters mounted as closely as possible to the under side of the table top for optimum denition without interfering with the mounting for the bucky used in radiography, and the result is to leave very small clearance between the bucky and carriage, for example as little as one-half inch in some cases. Such a space is insufficient to receive the phototube and its associated iiuorescent screen, and since it is not possible or practical to lower the tube carriage further, the expedient has been adopted in some cases of raising the table top to obtain additional space below the bucky, which not only requires considerable revision of the structure of an existing table but has the further disadvantage of raising the table top above the normal height for convenient use by the operator.

One of the primary objects of the present invention is to provide for the use of photoelectric timing apparatus in an existing uoroscopic table, cassette changer or other X-ray apparatus where the limitations of space have heretofore made photoelectric timing difiicult or impractical and without requiring reconstruction or rearrangement of the existing parts of the apparatus.

Another object is to provide a photoelectric timing pickup unit for use with a photoelectric timing device which includes a fluorescent screen of substantial area and which is so constructed that substantially all of the light emitted from the screen in use is concentrated on the phototube to give a highV degree of sensitivity to the unit for accurate timing.

It is also an object of the invention to provide a photoelectric pickup unit for use with a photoelectric timing device which is simple and economical to manufacture, which is easily installed on existing buckys and other pieces of X-r'ay equipment without requiring reconstruction or rearrangement of existing parts, and which accordingly makes it simple to adapt existing X-ray apparatus to use with a photoelectric timing device.

Other objects and advantages of the invention will be apparent from the following description, the accom-v panying drawing and the appended claims.

In the drawing- Fig. 1 illustrates a photoelectric pickup unit in accordance with the invention, the View being in elevation as viewed from the X-ray source and with portions broken away to illustrate details of internal construction;

Fig. 2 is a view partly in side elevation and partly broken away in vertical section showing the unit mounted on a bucky;

Fig.- 3 is an end elevational view of the unit;

Fig. 4 is an enlarged fragmentary section on the line 4-4 of Fig. 1;

Fig. 5 is an enlarged fragmentary View of a portion of the unit;

Fig. 6 is a fragmentary section showing a modied construction of a portion of the unit; and

Fig. 7 is a cassette tray embodying a pickup unit in accordance with the invention.

Referring to the drawing, which illustrates preferred embodiments of the invention, the pickup unit includes a relatively iiat and pan-like casing 11) having a peripheral ange 11 adapted to be secured by screws 12 to the housing 13 of a conventional reciprocating bucky shown fragmentarily in Fig. 2. A gasket 14 of felt or other suitable material for absorbing visible light without ab sorption of X-rays is positioned between the casing 1li and housing 13 to prevent entry of visible light to the interior of the casing 10 from the outside. At the end of the casing 10 is a portion 15 forming a housing for the phototube 16, and this portion of the casing is formed to extend around the end of the bucky housing 13 in such manner that the tube housing is opposite the end of the bucky and does not add any more to the thickness of the bucky than does the casing 10 itself.

The main portion of the casing 10 is thus readily pervious to X-rays traversing the bucky housing 13, within which, as shown diagrammatically in Fig. 2, the bucky diaphragm and panel 21 define a space 22 therebetween for receiving a cassette. The panel 21 is provided with an opening 23 through which the beam passes after traversing the cassette, and a similar opening 24 is provided in the bucky housing in line with opening 23. A lead diaphragm 25 having holes 26 of different sizes and shapes therethrough may be provided between the

openings

23 and 24, and means (not shown) are provided within housing 13 for adjusting this diaphragm 25 in accordance with the density of the tissue being radiographed to control the quantity of rays reaching the pickup unit.

Within the casing 10 is a at plate 30 of transparent material of relatively high refractive index, adapted to pipe light therethrough, satisfactory results having been obtained with a plastic such as Lucite (methyl methacrylate). This plate includes a rectangular portion at one end which is aligned with and of approximately the same area as the opening 24 in the bucky housing 13. The other end portion of plate 30 has its

sides

31 and 32 tapered to converge in the direction of the tube housing 15, and the end portion 33 of the plate is beveled and ground to provide a roughened surface as indicated in Fig. 5. This beveled end portion 33 underlies the phototube 16, and satisfactory sensitivity has been obtained with the phototube arranged with its photosensitive opening parallel with the beveled surface 33 as indicated by the line 35 in Fig. 2.

A fluorescent screen is positioned on each side of the rectangular portion of the plate 30, and the surfaces of this portion of the plate are roughened as indicated at 41 in Fig. 1 to facilitate entry into the interior of the plate by the light emitted from the screens 40. Satisfactory results have been obtained using for each screen 40 a type B-2 Patterson liuoroscopic screen, which comprises a stiff cardboard backing coated with calcium tungstate or other suitable liuorescent material, and the junctions between the screens and the plate 30 are shown as sealed by means of a suitable adhesive tape 42.

The plate 30 and fluorescent screens 40 are effectively Desired internal reflectivity within plate 30 is z obtained by polishing all surfaces of the plate except its

ground surfaces

33 and 41, and these polished surfaces may also be provided with a reflecting coating to reflect back into the plate any light traversing its polished surfaces from within, satisfactory results having been obtained by wrapping the tapered portion of the plate with bright aluminum foil or other suitable highly reflective material.

In operation with this pickup unit, the X-rays which traverse the cassette and bucky and strike the fluorescent screens 4l) cause the latter to emit visible light which is readily transmitted into the interior of the plate 30 through its roughened surface portions 41, and with this plate formed of a transparent material of suitably high reflective index such as glass, methyl methacrylate or polystyrene, the light is totally internally reflected within the plate until it reaches the beveled end portion 33, through which it is transmitted to actuate the phototube. In actual practice, it appears that substantially all of the visible light emitted from the screens ultimately reaches the phototube, since light escaping the plate before reaching the phototube is reflected back by the reflective coating 45, and since the beveled edges of the plate provide a suflicient collimating action to concentrate the light on the phototube.

This pickup device is readily constructed of such overall dimensions, and particularly of such overall thickness, that it may be successfully installed and operated in highly restricted spaces such even for example as in an X-ray table of the construction referred to above wherein only 1/2 inch clearance is available between the bucky and the tube carriage. For example, successful results have been obtained with the plate 30 formed of a sheet of Lucite 1A; inch in thickness and with the casing 10 less than 3/8 inch in overall depth. In this particular unit, the fluorescent screens and ground surfaces 41 of the plate are approximately 51/2 inches square, with the other dimensions being in proportion as shown in the drawing and with the surface 33 beveled at approximately 20 to the length of the plate and approximately 2/3 square inch in area. In addition, since the phototubes are commercially available with a diameter of only about 1.25 inches, the tube housing 1S need not be more than about 1.75 inches in diameter measured lengthwise of casing 10, and when the unit is mounted on a bucky, it does not interfere with the desired full lengthwise travel of the bucky in an X-ray table.

This unit also gives highly desirable results from the standpoint of sensitivity and thus makes possible highly acurate photoelectric timing of X-ray exposures. Instead of requiring the phototube to be positioned in line with the fluorescent screen, usually in line with the center of the X-ray beam, the invention effects' concentration on the phototube of substantially all the light emitted from the entire screen area and without utilizing mirrors or lenses requiring greater expense and a casing of greater size. Furthermore, although only one fluorescent screen could be used satisfactorily, with the use of two screens as shown, the total amount of visible light is correspondingly increased for greater sensitivity, this increased light being readily compensated for by suitable adjustment of the control circuit actuated by the phototube.

Fig. 6 shows fragmentarily a plate 50 which may be substituted for the plate 30 as described. Instead of employing separate fluorescent screens as described in connection with Fig. 4, the plate has crystals 51 of calcium tungstate or other suitable fluorescent material irnbedded in or coated on one or both of its surfaces which are interposed in the path of the X-ray beam. For example, if the plate 50 is composed of Lucite or other suitable plastic, these surfaces may be readily softened by means of a solvent to provide for directly imbedding and adhering the crystalsv in such softened surfaces. With the plate 50 formed in this manner, and substituted for the plate 30, the device will operate in the same manner already described. Also, it is possible to employ larger crystals in connection with the plate 50 than for coating the screens 40, and if this is done, a greater amount of light may be developed for still further increased sensi tivity, the loss of definition resulting from the larger crystals being unimportant since it is desired only to obtain light from the crystals and not to form an image therewith.

Fig. 7 shows a pickup unit in accordance with the invention embodied in a cassette tray for radiographic purposes such as radiographing thehand, foot or other extremity of a patient on an X-ray table. The casing 60 is in general the same as the casing 10 as described, except that it is provided on its upper surface with suitable retaining means 61 for a cassete. Since this device is used in the manner of a tray and is not secured to a casing as shown in Fig. 2, it will be understood that all portions thereof are provided with a suitable light tight cover which is adequately permeable by X-rays at least in the area overlying the fluorescent screen or screens.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufficient to receive said phototube therein, comprising an enclosed casing pervious to X-rays and including a thin portion adapted for insertion in the path of said beam, means on said casing spaced from said thin portion thereof and forming a housing adapted to receive said phototube and having communication with the interior of said casing, said thin casing portion being of substantially less thickness than said housing for insertion in said restricted space while supporting said housing in laterally spaced relation with the path of said beam through said restricted space, fluorescent means within said thin casing portion for emitting light therewithin in response to X-ray radiation incident thereon, a plate of transparent material in said thin casing portion, said plate including one portion 1ocated in the path of light emitted from said fluorescent means to receive light within the interior thereof from said fluorescent means and another portion extending from said one portion to said housing to transmit light to said housing for activating said phototube, said other portion of said plate being of converging effective light transmitting area in the direction of said housing to concentrate said transmitted light on said phototube, and means on the outer surfaces of said other portion of said plate for preventing emission of said transmitted light from said plate in the areas intermediate said fluorescent means and said housing.

2. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufficient to receive said phototube therein, comprising an enclosed casing pervious to X-rays and including a thin portion adapted for insertion in the path of said beam, means on said casing spaced from said thin portion thereof and forming a housing adapted to receive said phototube and having communication with the interior of said casing, said thin casing portion being of substantially less thickness than said housing for insertion in said restricted space while supporting said housing in laterally spaced relation with the path of said beam through said restricted space, fluorescent means within said thin casing portion for emitting light therewithin in response to X-ray radiation incident thereon, and a plate of transparent material in said thin casing portion including one portion located in the path of light emitted from said fluorescent means to receive light within the interior thereof from said fluorescent means and of substantially the same area as said fluorescent means, said plate including another portion extending from said one portion to said housing and having the side edges thereof converging in the direction of said housing to transmit to and concentrate on said phototube light received within said one portion from said phototube.

3. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufficient to receive said phototube therein, comprising an enclosed casing pervious to X-rays and including a thin portion adapted for insertion in the path of said beam, means on said casing spaced from said thin portion thereof and forming a housing adapted to receive said phototube and having a communication with the interior of said casing, said thin casing portion being of substantially less thickness than said housing for insertion in said restricted space while supporting said housing in laterally spaced relation with the path of said beam through said restricted space, fluorescent means Within said thin casing portion for emitting light therewithin in response to` X-ray radiation incident` thereon, a plate of transparent material in said thin casing portion, said plate including one portion located in the path of light emitted from said `fluorescent means to receive light within the interior thereof from said fluorescent means and another portion extending from said one portion to said housing to transmit light to said housing for activating said phototube, and means on the surface of said other portion of said plate for reiiecting back into said plate light traversing said surface from within said plate.

4. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufiicient to receive said phototube therein, comprising an enclosed thin casing perviou's to` X-rays and adapted for insertion in the path' of said beam,means on said casing forming a housing adapted to receive said phototube and having communication with the interior of said casing, said lcasing being of substantiall-y less thickness than said housing for insertion in said restricted space while supporting said. housing in lat erally spaced relation with the path of said beam through said restricted space, a plate of transparent material within said casing, fluorescent means on both surfaces of one portion of said plate for emitting light into said plate in response to X-ray radiation incident thereon, and said plate including another portion extending from said one portion to said housing to transmit said light to said housing for activating said phototube.

5. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufficient to receive said phototube therein, comprising an enclosed thin casing pervious to X-rays and adapted for insertion in the path of said beam, means on said casing forming a housing adapted to receive said phototube and having communication with the interior of said casing, said casing being of substantially less thickness than said housing for insertion in said restricted space while supporting said housing in laterally spaced relation with the path of said beam through said restricted space, a plate of transparent material within said casing for insertion therewith into the path of X-ray radiation into said restricted space, a fluorescent screen carried by said casing and adjacent the surface of one portion of said plate for emitting light into said plate in response to X-ray radiation incident thereon, said plate including another portion extending from said one portion to said housing to transmit said light to said housing for activating said phototube, said other portion of said plate being of converging effective light transmitting area in the direction of said housing to concentrate said transmitted light on said phototube, and means on the outer surfaces of said other portion of said plate for preventing emission of said transmitted light from said plate in the areas inter mediate said fluorescent means and said housing.

6. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insufficient to receive said phototube therein, comprising an enclosed thin casing pervious to X-rays and adapted for insertion in the path of said beam, means on said casing forming a housing adapted to receive said phototube and having communication with the interior of said casing, said casing being of substantially less thickness than said housing for insertion in said restricted space While supporting said housing in laterally spaced relation with the path of said beam through said restricted space, a plate of transparent material within said casing for insertion therewith into the path of X-ray radiation into said restricted space, a plurality of lluorescent crystals imbedded in at least one surface of one portion of said plate for emitting light into said plate in response to X-ray radiation incident thereon, said plate including another portion extending from said one portion to said housing to transmit said light to said housing for activating said phototube, said other portion of said plate being of converging effective light transmitting area in the direction of said housing to concentrate said transmitted light on said phototube, and means on the outer surfaces of said other portion of said plate for preventing emission of said transmitted light from said plate in the areas intermediate said fluorescent means and said housing.

7. A device adapted for use in combination with photoelectric means including a phototube for controlling an X-ray beam in a restricted space insuicient to receive 6 said phototube therein, comprising an enclosed casingv pervious to X-rays and. adapted for insertion i-n the path of. said beam, means on said casing forming a housing adapted to receive said phototube and having communication with the interior of said casing, said casing being of sub-- stantially less thickness than said housing for insertion 1n sald restricted space while supporting said housing inv laterally spaced relation with the path of said beam through said restrictedy space, iluorescent means within sald caslng for emitting light within said casing in response to X-ray radiationv incident thereon, a plate of transparent material in said casing, said plate including one por-A tron arranged to receive light within the linterior thereof from said fluorescent means and vanother portion extendf lng from said one portion into said housing to transmit light to said housing for activating' said phototube, and the end of said other portion of said plate Within said housing belng beveled along the edge thereof adjacent sald phototube to direct said light from said plate towards said phototube.

8. A device adapted for use in `combination with photo'- electric means including a photoelectric tube for control-V ling an X-ray beam in a restricted space insufficient to re- -ceive said phototube therein, comprising an enclosed cas mg pervious to X-rays and including a thin portion adapted for insertion in the path of said beam, means on said casing spaced from said portion thereof and forming a housing for receiving said photoelectric tube and having communication with the interior of said casing, said casing being of substantially less thickness than said housing for insertion in said restricted space while supporting said housing in laterally spaced relation with the path of said beam through said restricted space, a plate of transparent material positioned within said thin casing portion and including a portion of substantial area adapted to be positioned in the path of said beam, fluorescent means on either side of said plate portion for emitting light within said casing in response to X-ray radiation incident there on, the surfaces of said plate portion adjacent said fluorescent means being roughened to effect transmission of said light into the interior of said plate, the remainder of said plate being of decreasing width in the direction of said housing and extending into said housing in close proxirnity to said phototube to concentrate and transmit said light thereto, said plate having a beveled end portion adjacent said phototube, the surface of said beveled portion being roughened to transmit said light to said phototube, and means on said plate between said fluorescent means and said roughened end portion for reiiecting back into said plate light traversing the surface thereof from within said plate.

9. A device adapted for mounting on a bucky including a housing having means thereon for supporting an X-ray lilm for use in combination with photoelectric means including a phototube for timing the exposure of said lm to an X-ray beam, comprising a relatively dat casing adapted to be secured to said bucky housing with a portion thereof aligned with said lm supporting means to receive X-rays passing through said lm, means on said casing forming a housing for said phototube having communication with the interior of said casing, said casing being substantially less thick than said phototube housing for insertion below said bucky housing in a restricted space insufficient to receive said phototube housing while supporting said phototube housing in laterally spaced relation with the path of said beam through said restricted space, said phototube housing being offset vertically with respect to said casing in position to extend around the end of said bucky housing, fluorescent means within said casing for emitting light within said casing in response to X-ray radiation incident thereon, a plate of transparent material mounted in said casing and ncluding one portion located in the path of light emitted from said uorescent means to receive said emitted light within the interior thereof from said uorescent means and another portion extending from said one portion to said tube housing to transmit said light to said housing for activating said phototube, said other portion of said plate being of converging effective light transmitting area in the direction of said housing to concentrate said transmitted light on said phototube, and means on the outer surfaces of said other portion of said plate for preventing emission of said transmitted light from said plate in the areas intermediate said fluorescent means and said housing.

10. A device adapted for use in combination with photoelectric means including a phototube for timing exposure to an X-ray beam in a restricted space insufcient to receive said phototube therein, comprising an enclosed relatively at casing pervious to X-rays on one side thereof and including a portion adapted for insertion in the path of said beam, means adjacent said portion of said casing for receiving and retaining an X-ray film in the path of said beam, means on said casing spaced from said portion thereof and forming a housing adapted to receive said phototube and having communication with the interior of said casing, said casing being of substantially less thickness than said housing for insertion in said restricted space While supporting said housing in laterally spaced relation with the path of said beam through said restricted space, uorescent means within said casing for emitting light within said casing in response to X-ray radiation incident thereon, a plate of transparent material mounted in said casing and including one portion located in the path of light emitted from said fluorescent means to receive said emitted light within the interior thereof from said fluorescent means and another portion extending from said one portion to said tube housing to transmit said light to said housing for activating said phototube, said other portion of said plate being of converging eifective light transmitting area in the direction of said housing to concentrate said transmitted light on said phototube, and means on the outer surfaces of said other portion of said plate for preventing emission of said transmitted light from said plate in the areas intermediate said uorescent means and said housing.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,214,209 Triplett Sept. 10, 1940 2,225,439 Arens et al. Dec. 17, 1940 2,347,665 Christensen et al May 2, 1944 2,358,867 Madan Sept. 26, 1944 2,441,324 Morgan et al. May 11, 1948 2,583,132 Altar et al. Ian. 22, 1952