US3735130A

US3735130A - Diaphragm-type high speed spot film device

Info

Publication number: US3735130A
Application number: US00166394A
Authority: US
Inventors: J Bock; M Sivertsen
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1971-07-27
Filing date: 1971-07-27
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22

Abstract

Radiographic film is transported intermittently between a pressure-producing diaphragm and a platen, each of which has an x-ray fluorescent screen on its face. The diaphragm constitutes a wall of a chamber which is subject to being depressurized when the film is in transport and to being pressurized when the film is in radiographic position. The film contact pressure chamber is supplied and exhausted through flexible hoses which lead to a stationary pump. The pump has a chamber and a diaphragm which is displaced in one direction to generate pressure and is retracted in the other direction by an electromagnet to relived the pressure.

Description

United States Patent [191 Bock et al.

[451 May 22,1973

[54] DIAPHRAGM-TYPE HIGH SPEED SPOT FILM DEVICE [75] Inventors: John W. Bock, Greendale; Marvin L. Sivertsen, Milwaukee, both of Wis. [73] Assignee: General Electric Company, Schenectady, NY.

[22] Filed: July 27,1971

[21] Appl. No.: 166,394

[52] US. Cl ..250/66, 250/68 [51] Int. Cl.....G01n 21/34, GOln 23/04, HOlj 37/22 [58] Field of Search ..250/66, 68

[56] References Cited UNITED STATES PATENTS 2,468,381 4/1949 Sussin ..250/66 3,535,518 10/1970 Fischer ....250/66 3,153,145 10/1964 Yerkovich ..250/68 1,938,455 12/1933 Kelley ..250/66 X Primary Examiner-James W. Lawrence Assistant Examiner-T. N. Grigsby Attorney- Ralph G. Hohenfeldt, Jon Gealow and Arthur V. Puccini [57] ABSTRACT Radiographic film is transported intermittently between a pressure-producing diaphragm and a platen, each of which has an x-ray fluorescent screen on its face. The diaphragm constitutes a wall of a chamber which is subject to being depressurized when the film is in transport and to being pressurized when the film is in radiographic position. The film contact pressure chamber is supplied and exhausted through flexible hoses which lead to a stationary pump. The pump has a chamber and a diaphragm which is displaced in one direction to generate pressure and is retracted in the other direction by an electromagnet to relived the pressure.

9 Claims, 5 Drawing Figures PATENTEU IW 3,735,130

sum 1 OF 3 1 2:1 5 9 1 60 E 57 g2 I MOTOR T: CONTROL 3?) 5) I TTTTTT I 55 53 52 l 6A 8 56 M 34 O l 65 ii 48 49 T a i 46 5O LOGIC CONTROL x30 INVENTORS JOHN W BOCK Y MARVIN L. SIVERTSEN 2) 23 B 24 w 25 )U/ 'r CA;

AT TOR N EYS MQE INVENTORS JOHN W. BOCK MARVIN L. SIVERTSEN ATTORNEYS SHEET 2 BF 3 PATENTEL EH22 I975 PATENTED MY 2 2 I973 SHEET 3 OF 3 lllllh INVENTORS JOHN W. BOCK MARVIN L. SIVERTSEN 1 DIAPHRAGM-TYPE HIGH SPEED SPOT FILM DEVICE BACKGROUND OF THE INVENTION Conventional x-ray spot film devices comprise a housing which is equipped with a fluorescent device such as an x-ray image intensifier or a fluorescent screen. A film is held in storage outside of the x-ray beam. When the examining radiologist observes on the fluorescent device something of diagnostic interest which he would like to permanently record on the film, he operates a control which projects the film into the x-ray beam after which he makes an exposure. To shorten the exposure, x-ray fluorescent screens are usually positioned on opposite sides of the film. It is desirable to have high uniform contact pressure between the screens and film because blurred zones appear on the film wherever contact pressure is imperfect as is well known.

Several different methods have been employed for creating contact pressure between screens and film. The most common method is to install intensifying screens permanently within a cassette along with layers of resilient material which are subject to compression by closure of the cassette cover.

Another method is to enclose the film in a plastic bag between two screens and two light-impervious sheets. When the bag is evacuated, atmospheric pressure presses the screens against the film.

Still another method is to transport radiographic film between two closed loop belts which are in contact with each other andwhich are coated with fluorescent material. In a practical device, means are provided for tensioning the belts simultaneously to develop contact pressure with the intervening film.

Although fairly consistent results have been obtained with the above methods, it is well known that none of them create truly high contact pressure between the film and screen consistently nor do they develop anywhere near the compressive stress which the film is capable of withstanding. Another disadvantage of prior spot film devices which use cassettes or evacuated plastic bags is that they are limited to use of individual sheets of film and are not readily adaptable to use of roll film. The belt-type spot film device is capable of using roll film although it is inherently pressure limited.

SUMMARY OF THE INVENTION A general object of this invention is to overcome the above-cited and other disadvantages by providing a spot film device which presses the x-ray fluorescent screens and film together during an xray exposure by means of a metal or other suitably pliable diaphragm which may be quickly distended and retracted to respectively create and relieve contact pressure between radiographic film and fluorescent screens.

A further object is to provide a diaphragm-type spot film device wherein the fluorescent screens are mounted permanently on the diaphragm and on a platen.

Another object of this invention is to sequentially pressurize and depressurize the film contacting diaphragm by means of a pump that is simple and compact and adapted for being located in the limited space which is available in x-ray spot film devices associated with diagnostic x-ray tables.

A more general object of the invention is to provide an air pressure operated device for creating high uniform contact pressure between x-ray fluorescent screens and radiographic film and which is adapted for being installed in the conventional spot film tunnel above an x-ray t able or within an x-ray table beneath the table top and in other diagnostic x-ray apparatus.

How the foregoing and other more specific objects are achieved will appear from time to time throughout the course of the detailed description of a preferred embodiment of the invention which will be set forth hereinafter.

Briefly stated, the new spot film device comprises a housing with an x-ray transparent window. Aligned with the window in the housing is a platen on which an x-ray fluorescent screen is mounted. There is a diaphragm with a fluorescent screen adhered to it in substantial parallelism and spaced from the platen. The diaphragm is supported in a rigid chamber which has a small air volume so that introduction of a small amount of air under pressure will distend the diaphragm appreciably. Means are provided for transporting film between the screens from a feed cassette to a take-up cassette. Means are also provided for slicing the film at any time so that the take-up cassette may be removed along with the exposed film which it contains and sent to the darkroom for development.

In the preferred embodiment, a diaphragm-type pump is proposed for delivering and exhausting pressurized air to and from the film contact pressure diaphragm chamber. The pump diaphragm is distended with a spring and is retracted by an electromagnet. Distension of the pump diaphragm displaces air which is delivered by means of flexible hoses to the film contact pressure generating chamber.

An illustrative embodiment of the invention will now be described in reference to the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 4 is a vertical cross sectional view of an actual v embodiment of the new spot film device; and

FIG. 5 is a plan view, with parts omitted, showing the spot film device in a forward active radiographic posi' tion together with the means for advancing the device between active and parked positions.

DESCRIPTION OF A PREFERRED EMBODIMENT The new spot film device may be used in a diagnostic x-ray table such as is illustrated in FIG. 1. The table comprises a body 10 which has an x-ray transparent patient supporting top 11. In the depicted arrangement, there is an x-ray tube, not shown, within table body 10 and positioned to project its beam through table top 1 1 and through a subject who may be reposed upon the table top. The x-ray tube is supported on a column 12 which is adapted for being translated longitudinally of the x-ray table body in a well-known manner. The central ray of the x-ray beam coincides with the center of an x-ray image intensifier tube, not visible, but which is located within a housing 13.

The optical image which results from conversion of the x-ray image by the intensifier within housing 13 is viewed by a TV camera, not shown, which is contained in a housing 14. With a closed circuit TV chain, the op tical image may thus be displayed on a TV monitor, not shown, in which case the radiologist may visualize a portion of the patients anatomy on a TV screen, in a manner that is analogous to using a conventional direct viewing fluoroscopic device.

Image intensifier housing 13 is mounted on a spot film tunnel 15 in such manner that the x-ray image may be intercepted by the intensifier in housing 13 without appreciable absorption. The new spot film device is normally parked in the rear part 16 of tunnel 15. In F 1G. 1, only the cylindrical film feed cassette 17 of the spot film device is visible. The feed cassette 17, as well as the take-up cassette on the other side may be made accessible through an access door, not shown, in the side of tunnel housing 18. The spot film device may be projected from its parked position in the rear part 16 of housing 15 to a forward position in housing 18 in which case the x-ray image which was formerly projected to the intensifier on housing 13 is intercepted by a film in the spot film device. As is well known, the x-ray tube, the spot film device and the image intensifier are sometimes conversely arranged in diagnostic x-ray tables; that is, the x-ray tube is mounted over the x-ray table top and the spot film device is movably mounted under the x-ray table top within the table body and the intensifier is mounted under it in such manner that the x-ray tube and intensifier will remain in alignment when their supporting column is shifted longitudinally of the table. These constructions and modes of operation are generally known in the art and need not be elaborated further.

Attention is now invited to FIG. 2 which shows schematically the principal elements of the new spot film device in conjunction with some schematically represented components of an x-ray table. The table includes a top 1 1 as explained earlier. Within the body of the table which is not shown in this figure is an x-ray tube which is symbolized and marked with the numeral 21. The x-ray tube usually cooperates with x-ray

field defining shutters

22 and 23 which are coupled for joint operation as indicated by the dashed line 24 and driven by a servo motor 25. A logic control 30 adjusts the shutters on command of the operator so that only that portion of the patients body which is to be examined or radiographed is subjected to x-radiation. The logic control may also adjust the shutters in accordance with the amount by which the radiographic film is advanced in the spot film device so that double or overlapping exposures are prevented. Shutter control systems of the type just outlined are known in the art and need not be described in further detail.

The spot film device in FIG. 2 is adapted to expose incremental lengths of a roll of radiographic film a fragment of which is marked with the numeral 31 in FIG. 2. The film may be advanced by driving a sprocket 32 with a motor 34. A motor control 33 is adapted for energizing motor 34 and thus advancing the film on push button command of the operator or automatically depending on its setting. In actual case, the adjustable motor control 33 and logic control 30 are interconnected so that the film 31 will be advanced and the

shutters

22 and 23 will be opened or closed coordinately depending on the size of the film area 31 which was last exposed and on the size of the field which is to be exposed next.

The spot film device shown in FIG. 2 is adapted for permitting unrestricted intermittent advancement of the film between exposures and for compressing the film 31 uniformly over the entire exposure area between two x-ray fluorescent screens during an x-ray exposure interval.

For the purposes just mentioned, the spot film device is provided with a stationary platen 37 which is rigid but does not absorb appreciable radiation. Adhered to the platen is a thin layer of felt 38 or other cushion type material which has an x-ray fluorescent sheet or screen 39 adhered to it. When film 31 is being advanced, it bears lightly on lower screen 39 whereas during exposure intervals, the film is clamped or in uniform high pressure contact with fluorescent screen 39.

A thin metal or other suitably pliable diaphragm 40 is used to develop contact pressure between the fluorescent screens and the film. Diaphragm 40 has a depressed channel 41 inwardly of its edges so that its central area 42 will be more free to distend when pressurized air or gas is applied to the top of the diaphragm as shown in FIG. 2. Bonded to the bottom of central area 42 of diaphragm 40 is a thin aluminum sheet 43 which is contoured slightly convex in the downward direction. Adhered to the convex face of aluminum sheet 43 is another x-ray fluorescent sheet or screen 44. Thus, screen 44 also assumes a slightly convex configuration. When the central area 42 of diaphragm 40 is distended under the influence of air pressure, the center of screen 44 will make first contact with film 31 thereby initiating the process of pressing the latter against the platen. An instant after air pressure is applied to the top of diaphragm 41 and film contact is made, the contacting area enlarges and radiates outwardly to the edges of the film until there is uniform contact over its entire exposure area. At this time the diaphragm 41 central area 42 is substantially flat rather than convex due to its reaction against screen 39, cushion material 38 and the underlying rigid platen 37. Making central contact first permits atmospheric air to be squeezed out from the center to the edges between the interfaces of film 31 and

fluorescent screens

39 and 44 which are on opposite sides of the film.

Diaphragm 40 constitutes the bottom of a chamber whose top may be an impervious metal plate such as 45 which is shown fragmentarily in FIG. 2. Plate 45 is spaced a small distance from diaphragm 40 to create a small volume air pressure chamber which is marked 46. It should be understood that the perimeter of air chamber top 45 is sealed with respect to the perimeter of diaphragm 40 to define the closed air space or pressure chamber 46. It is desirable to reduce the pressurized air space 46 above the diaphragm as much as possible so that the diaphragm 40, and particularly its central region 42, will start to distend when a small quantity of pressurized air is introduced into the chamber 46.

Chamber 46 communicates with a header 47 to which two

flexible hoses

48 and 49 are connected. These hoses are coupled to a T-fitting 50 which has one branch 51 connected to a plate 52 that forms the bottom of a pump chamber 53 which is part of a pump assembly that is generally designated by the reference numeral 54. By virtue of pump 54 being connected with the spot film device by means of

flexible hoses

48 and 49, the pump may be fixedly mounted in the spot film tunnel of an x-ray table and the spot film device may be transferred from its parked position to its forward or active position without severing its connection with the pump.

Pump 54 is a diaphragm type which is distinguished by being quick-acting, without frictional surfaces and compact, making it suitable for use in x-ray apparatus where space is at a premium. Pump 54 comprises bottom 52 and side walls 55 which are split into two sections between which a thin metal or other suitably pliable diaphragm 56 is sealed. Bonded onto the top of diaphragm 56 is a rigid pressure plate 57. Pump diaphragm 56 has a marginal downwardly curved channel 58 for increasing its flexibility and capability for distending or being displaced. The space above pump diaphragm 56 is enclosed by planar top 59 which may be opened to the atmosphere and need not-be leakproof since no useful pressure is developed above the pump diaphragm 56. Fastened to the top of rigid pressure plate 57 by means of a flange 60 is a solenoid plunger or armature 61 which extends freely through the top 59 of the pump. A compression spring 62 surrounds armature 61 and is interposed between the bottom of top 59 and pressure plate 57 so as to bias the pressure plate and diaphragm 56 downwardly and thereby displace air from lower pump chamber 53. Armature 61 is surrounded by an electromagnet coil 63 which can be energized from a d-c source, not shown. When coil 63 is energized, armature 61 is attracted upwardly and diaphragm 56 is raised to thereby depressurize pump chamber 53 in which case air will be drawn into the pump chamber. Thus, it will be seen that pump 54 has the properties of a single stroke reciprocating piston type pump except that there is no opportunity for leakage sincediaphragm 56 is impervious.

In FIG. 2, it will be evident that when pump diaphragm 56 is displaced downwardly, air under pressure will be driven to the spot film device through

hoses

48 and 49, thereby pressurizing film 31 under the influence of diaphragm 40 between

fluorescent screens

39 and 44. If there were a leak in the system, subnormal pressure would develop in pump chamber 53 when its diaphragm 56 is retracted to relieve the pressure on the spot film device. During quickly successive operation, the pump would encounter lower and lower pressure and might eventually be incapable of developing sufficient contact pressure between the film and screens. To preclude this possibility, a check valve assembly 64 is provided. This assembly junctions with branch 51 of T-fitting 50. If pressure in chamber 53 is below atmospheric pressure when pump diaphragm 56 is retracted, air will be drawn in through an orifice 65 of the check valve assembly to make up for any air that may have been lost due to a leak, if any.

An actual embodiment of the new spot film device and its associated pump are shown in FIGS. 3, 4 and 5, respectively. In these figures, parts which have been discussed in connection with the previous figures are given the same reference numerals.

In FIG. 4 where the device is seen in cross section looking toward the rear, near its bottom one may see that the spot film device comprises opposite sides 70 and 71 of a base member in which there is an x-ray transparent window opening 36 over which there is a platen 37. The platen may be a rigid polymer or suitably x-ray transparent metal such as aluminum. A pliable compressible layer 38 of flexible foam or felt is adhered to platen 37 and the lower x-ray intensifying screen 39 is adhered on the layer. The left base member is integral with a channel box 72 to which a detachable cylindrical take-up film cassette 73 is attached. Box 72 is slotted at 74 to create a passageway for film 31, which exits from the spot film device through the passageway and is taken up in an exposed condition in cylindrical take-up cassette 73. In the bottom of take-up cassette 73 is a felt strip 75 which cooperates with a long semi-cylindrical element 76 to provide a light seal. Semi-cylindrical element 76 is coated with velvet and it flat on one side. When element 76 is rotated through a half circle by an external manual knob 95, see FIG. 5, its circular periphery will bear on film 31 and felt strip 75 to effectuate a light seal. Thus, when film 31 is cut by means which will be described, cassette 73 along with block 72 may be detached in a lighted room without there being any possibility of light entering through passageway 74 which would cause fogging of the film.

The film feed cassette 17 shown in hidden lines in FIG. 1 and in section at the right side of the assembly in FIG. 4 is similar to take-up cassette '73 and is attached to member 69 which has a film exit passageway or slot 77 in it. There is a semi-cylindrical light seal 78 inside of cassette 17 which can be tumed manually and cooperates with a felt pad 79 to effectuate a light seal when the cassette 17 is being transported.

Means for transporting film 31 intermittently through the spot film device will now be described. The film advance mechanism includes a sprocket 32 whose teeth engage sprocket holes in the edge of the film. The sprocket is on a spline shaft which, as can be seen in FIG. 5, extends from the front to the rear of the spot film device. Spline shaft 100 is joumaled in a front bearing 101 and a rear bearing 102. A gear 103 is fastened to the spline shaft adjacent the rear bearing. This gear is meshed with one or more gears such as 104 in a gear train which is driven by a film drive motor 34 which was mentioned earlier in connection with discussing the FIG. 2 schematic diagram of the spot film device. The interval during which motor 34 is driven and, hence, the amount of film advance is governed by the setting of a motor control 33 or logic circuit which was mentioned earlier in connection with discussing FIG. 2. Sprocket 32 is joumaled in the spot film device and remains engaged in the sprocket holes of film 31 at all times. The sprocket merely slides on spline shaft 100 when the spot film device is moved back and forth longitudinally within its housing. This arrangement permits the film to be advanced when the device is in transport from active to parked position or vice versa. Thus, there is no delay between the time that the spot film device reaches its active radiographic position and the making of an exposure.

The mechanism for advancing the spot film device to its active position and for retracting it to its parked position will now be described in reference to FIGS. 4 and 5. Toward the rear of the spot film tunnel or housing 18 is a carriage drive motor on whose shaft there with its central portion broken away in FIG. 5 but it will I be understood that one side of the chain is fastened by means of clamps 114 and 1 15 to an upwardly extending member 116 which is integral with the spot film device. Thus, when the chain 1 13 is translated under the influence of reversible motor 110, the spot film device will move forwardly or backwardly depending on the direction of motor rotation which is commanded.

The spot film device is on sliding bearings which operate with guides for enabling the device to be transported rapidly between its parked and active positions with minimum energy. For instance, upwardly extending block 116 is provided with an internal bushing 117 which slides on a fixed shaft 1 18 that extends longitudinally of the spot film tunnel or housing 18. This ar rangement offers sliding support of the spot film device on one of its sides. It is further supported for sliding on its other side on a laterally extending flat track 1 19. An edge of track 119 registers in a slot 120 of a downwardly extending bearing block 121 which is fastened to and travels with the spot film device.

Immediately to the left of film advance sprocket 32 in FIG. 4 there is another velvet coated semi-cylindrical light seal 82 which cooperates with a felt strip 83 to effectuate a light seal similarly to the light seals which have been described. Semi-cylinder 82 is also rotatable manually by an external knob, not shown. The purpose of light seal 82 is to prevent entry of light into the unexposed film within the spot film device when the film has been cut off and take-up cassette 73 has been removed.

The film may be cut by the shearing action between a movable blade 86 and a stationary blade 87. The movable blade 86 is normally displaced away from the edge of the film so as to not interfere with transport of the latter. Blade 86 is mounted on a guided translatable mechanism 88 which is mounted in downwardly extending channel 72. Channel 72 is integral with the spot film device and transports with it. Mounted on the top of the channel, as can be seen in FIG. 5, is a small motor 89 which is mechanically coupled with the transport mechanism 88. Thus, when motor 89 is driven at the command of the operator, blade 86 is translated crosswise of the film, thereby shearing it. The film shearing mechanism is known in the art and can be variously devised by a skilled designer so it need not be described in any greater detail.

Aligned with x-ray window opening 36 in the bottom of the spot film device and immediately below it is a plastic x-ray transparent palpator 124 of a type which is known in the art and is commonly used for imposing pressure on the body of a patient during an x-ray examination. The palpator 124 may be caused to press the patient by raising and lowering the entire spot film device on its supporting column 12 which may be seen in FIG. 1. The palpator 124 is located beneath the x-ray image intensifier 13 at all times. The palpator 124 slides into grooves 125 in parts 126 so it may be removed at will. Grooves are also provided to insert masks and grids, not shown. An intermediate member 127 is fastened to the stationary spot film device housing 18, allowing space for a phototimer 128.

The construction of the film contact pressure diaphragm and its cooperating parts will now be recapitulated in reference to FIG. 4 using the same reference numerals where possible as were used in reference to the schematic showing of the invention in FIG. 2. FIG. 4 illustrates that the central x-ray beam may pass upwardly through the center of downwardly protruding plastic palpator 124 and through the center of window opening 36. A relatively stiff plastic or x-ray transparent metal platen 37 extends across window opening 36 and provides a support for resisting film contact pressure. A thin layer of pliable material such as felt or polyurethane foam 38 is adhered to platen 37 and is coextensive in area with it. A thin x-ray intensifying screen 39 is adhered to the top surface of pliable layer 38. Film 31 runs parallel with the planar intensifying screen 39.

The film pressure producing diaphragm is located above the film passageway and is generally designated by the reference numeral 40. This thin metal or plastic diaphragm has a continuous downwardly depending perimetral indentation near its edge to make the diaphragm less resistant to deflection when its top is subjected to a pressurized fluid such as air. The lower face of diaphragm 40 has a thin sheet of comparatively rigid material such as aluminum or a plastic adhered to it. Sheet material 43 is slightly convex downwardly and has the upper x-ray intensifying screen 44 adhered to it so that the screen assumes a similar slightly convex contour. It will be evident that when the top of diaphragm 40 is subjected to air pressure its central region will be distended downwardly and, due to the slight convexity of sheet 43 and intensifying screen 44, the center of the intensifying screen will make first contact with film 31 thus squeezing air out of the interfaces between film 31 and upper and lower intensifying

screens

44 and 39. As the application of pressure proceeds, the contact area enlarges toward the edges of the screens thereby squeezing the remaining air outwardly toward the edges. Eventually, that is in a few milliseconds, flat or planar contact is established between the intensifying screens and the film and the making of an unblurred exposure is possible. The added flexibility imparted to the diaphragm by its marginal depression 41 enables planar contact to be established. The edges of diaphragm 40 are sealed in an airtight fashion with epoxy resin or any suitable means. The top 45 of the air chamber is impervious and defines an air pressure space or volume 46 above diaphragm 40. As can be seen in FIG. 3, space 46 communicates with a cavity in header 47 which is supplied from an air hose 48 which leads back to pump 54. Note that air receiving chamber 46 is very thin and has relatively low volume so it requires admission of only a small quantity of air to distend diaphragm 40 appreciably. A few pounds per square inch of gauge pressure is adequate for getting good air bubble free contact pressure between the film and intensifying screens.

FIG. 3 shows the pump assembly 54 which is used to generate and relieve pressurized air in diaphragm chamber 46. The pump assembly 54 is preferably located in the rear part 16 of the spot film device housing or tunnel 18. As can be seen in FIG. 3, pump 54 is mounted at an elevation above that of the spot film device so that the latter may move under it when it is returned to its parked position. Pump 54 may be conveniently supported on a plurality of brackets such as 91 which are bolted at 92 to the rear part 16 of housing 18 and are also held by means of machine screws 93 to the top 59 of the pump.

Connected to the bottom plate 52 of pump 54 is the T-fitting 50 to which

hoses

48 and 49 are connected. Only the hose 48 which is on the right side of the pump assembly is apparent in viewing FIG. 3 but it will be understood that the other hose 49 which appears in FIG. 2 is also used to effectuate delivery of air from pump 54 to the film contact pressure diaphragm 40 with minimum impedance. One may also see in FIG. 3 that there is a check valve assembly 64 which contains a spring 94 that acts on aball 95 in cooperation with the seat of an orifice 65. As explained earlier, this check valve assembly permits drawing in air to make up for any air that may be lost through a small leak when the diaphragms in both the spot film device and the pump are under pressure and distended. Since the system is essentially closed, the loss of air during a pressurized interval must be made up rapidly during a non-pressurized interval or sub-atmospheric pressure will develop within the pumping chamber. However, leakage, even after extended use, is very improbablebecause it is relatively easy to avoid leaks where diaphragms are used as opposed to pumps and pressure creating devices that have relatively movable parts.

In summary, a new spot film device that permits use of either roll film or sheet film and avoidance of the use of a cassette has been described. The spot film device is mounted for bi-lateral translation between a parked position and an active or radiographic position in a spot film tunnel or housing which may be above or below a patient supporting surface. Roll film cassettes are easily attached and detached so that exposed film may be removed for development at any time. The large quantity of unexposed film which can be stored in the feed cassette makes possible the taking of an extended series of radiographs without necesitating cassette handling. The spot film device is distinguished by generating uniform film contact pressure with a quick-acting air driven diaphragm which squeezes air out from the center toward the edges of the film. The device is simple, quiet in operation and durable. No massive components need be moved to effectuate application and relief of film contact pressure.

Air for operating the film contact pressure creating diaphragm is obtained in the preferred embodiment from a diaphragm-type pump in which the diaphragm is distended by a spring during pressure delivery so that the pressure is always substantially the same. The return stroke of the pump diaphragm is effectuated with an electromagnet or solenoid which also compresses the spring and puts it in readiness for the next ensuing pressure stroke. Those skilled in the art will appreciate, however, that the film contact pressure diaphragm may be operated from a pressurized air or gas tank if desired. This, of course, is expensive because it involves equipment for regulating pressure as well as a valve system for applying and relieving pressure at appropriate times during operation of the spot film device. Other types of pumps could also be substituted at the expense of sacrificing the simplicity, compactness and absence of moving parts in the diaphragm-type pump.

Although a preferred embodiment of the invention has been described in considerable detail, such description is to be considered illustrative rather than limiting, for the invention may be variously embodied and is to be limited only by interpretation of the claims which follow.

We claim:

1. In a spot film device for selectively positioning film in the path of an x-ray beam in diagnostic x-ray apparatus including a housing,

guide means in said housing,

a spot film device that is mounted for being moved unitarily and selectively in and out of an x-ray beam path on said guide means within said housing, a. the improvement in said spot film device includ- 1. x-ray transmissive platen means disposed substantially normal to the x-ray beam path, said platen means being movable in said housing,

2. means adapted to transport film in substantial parallelism with said platen means,

3. a film compression chamber substantially aligned with and movable jointly with said platen means and having a diaphragm means in a side thereof which is substantially parallel with said platen means thereby defining a film pathway between said diaphragm means and said platen means,

4. means for supplying pressurized gas to said chamber to distend said diaphragm means and thereby press a film intervening between said platen means and said diaphragm means toward said platen means,

b. pump means comprising a chamber and a flexible pump diaphragm means sealingly closing said chamber,

c. spring means biasing said pump diaphragm means in one direction that effects a certain volume and pressure with said chamber,

. electromagnetic means operatively coupled with said pump diaphragm means to urge said pump diaphragm means in an opposite direction and thereby effect a different volume and pressure in said pump chamber,

e. conduit means communicating between said film compressionchamber and said pump chamber, and

f. said electromagnetic means being selectively energizeable to oppose said spring means whereby to alternately pressurize and depressurize said chambers.

2. The invention set forth in claim 1 including:

a. a thin metal back-up plate adhered to said diaphragm and having an area that is substantially equal to but slightly less than said diaphragm means and is juxtaposed therewith, said back-up plate being normally convex toward said film path away from said diaphragm means and being rigid but thin enough to flatten outwardly from its center when said diaphragm means is subjected to gas pressure.

3. The invention set forth in claim 1 including:

a. planar x-ray fluorescent screen means which are in substantial parallelism with said diaphragm means and said platen means and are on opposite sides, respectively, of said film path.

4. The invention set forth in claim 3 including:

a. a layer of compressible material disposed on said platen means, the said fluorescent screen which is on the platen side of said film path being adhered to said layer.

5. The invention set forth in claim 1 wherein:

a. said pump means is stationary relative to said film compression chamber in said housing means, and

b. said conduit means is a flexible hose.

6. In diagnostic x-ray apparatus including a spot film device located on a side of the patient-supporting surface of an x-ray table which is opposite to the side on which an x-ray source is located,

stationaryfluoroscope means positioned to receive an x-ray image from a subject supported on the table and to convert said x-ray image to an image which may be visualized, said spot film device being selectively movable between a storage position and an active position in a plane between said fluoroscope means and the tabie top,

an exposed film cassette on one side of said transportable means and an unexposed film cassette on the other side thereof,

means on said transportable means adapted to selectively convey film from one cassette to the other, the improvement in said spot film device comprismg:

a. a movable gas operated film compression chamber, said chamber having a diaphragm sealingly installed in a side thereof, said diaphragm being distensible toward a film path in response to gas pressure being applied to the interior of said chamber and said diaphragm being retractable when said pressure is reiieved,

b. platen means in substantial parallelism with said diaphragm means and defining said film path therewith,

c. means for selectively applying and relieving pressurized gas to and from said film compression chamber, whereby to alternately press a film against said platen means and to release the film for conveyance,

d. relatively stationary pump means comprising a chamber and a flexible pump diaphragm means sealingly enclosing said chamber,

e. spring means biasing said pump diaphragm means in one direction that effects a certain volume and pressure within said chamber,

f. electromagnetic means operatively coupled with said pump diaphragm means to urge said pump diaphragm means in an opposite direction and thereby effect a different volume and pressure in said pump chamber,

g. conduit means communicating between said film compression chamber and said pump chamber, and

h. said electromagnetic means being selectively energizeable to oppose said spring means whereby to alternately pressurize and depressurize said chambers.

7. The invention set forth in claim 6 including:

a. x-ray fluorescent screens attached to said platen means and said diaphragm means, respectively.

8. The invention set forth in claim 6 including:

a. a thin flexible back-up plate means adhered to and distensible with said diaphragm means and having an area slightly less than said diaphragm means and being slightly convex toward said film path, and

b. a fluorescent screen adhered to said back-up plate means.

9. The invention set forth in claim 6 including:

a. a compressible layer adhered to said platen means,

and

b. an x-ray fluorescent screen adhered to said layer.

Claims

1. In a spot film device for selectively positioning film in the path of an x-ray beam in diagnostic x-ray apparatus including a housing, guide means in said housing, a spot film device that is mounted for being moved unitarily and selectively in and out of an x-ray beam path on said guide means within said housing, a. the improvement in said spot film device including: 1. x-ray transmissive platen means disposed substantially normal to the x-ray beam path, said platen means being movable in said housing, 2. means adapted to transport film in substantial parallelism with said platen means, 3. a film compression chamber substantially aligned with and movable jointly with said platen means and having a diaphragm means in a side thereof which is substantially parallel with said platen means thereby defining a film pathway between said diaphragm means and said platen means, 4. means for supplying pressurized gas to said chamber to distend said diaphragm means and thereby press a film intervening between said platen means and said diaphragm means toward said platen means, b. pump means comprising a chamber and a flexible pump diaphragm means sealingly closing said chamber, c. spring means biasing said pump diaphragm means in one direction that effects a certain volume and pressure with said chamber, d. electromagnetic means operatively coupled with said pump diaphragm means to urge said pump diaphragm means in an opposite direction and thereby effect a different volume and pressure in said pump chamber, e. conduit means communicating between said film compression chamber and said pump chamber, and f. said electromagnetic means being selectively energizeable to oppose said spring means whereby to alternately pressurize and depressurize said chambers.

2. The invention set forth in claim 1 including: a. a thin metal back-up plate adhered to said diaphragm and having an area that is substantially equal to but slightly less than said diaphragm means and is juxtaposed therewith, said back-up plate being normally convex toward said film path away from said diaphragm means and being rigid but thin enough to flatten outwardly from its center when said diaphragm means is subjected to gas pressure.

3. The invention set forth in claim 1 including: a. planar x-ray fluorescent screen means which are in substantial parallelism with said diaphragm means and said platen means and are on opposite sides, respectively, of said film path.

4. means for supplying pressurized gas to said chamber to distend said diaphragm means and thereby press a film intervening between said platen means and said diaphragm means toward said platen means, b. pump means comprising a chamber and a flexible pump diaphragm means sealingly closing said chamber, c. spring means biasing said pump diaphragm means in one direction that effects a certain volume and pressure with said chamber, d. electromagnetic means operatively coupled with said pump diaphragm means to urge said pump diaphragm means in an opposite direction and thereby effect a different volume and pressure in said pump chamber, e. conduit means communicating between said film compression chamber and said pump chamber, and f. said electromagnetic means being selectively energizeable to oppose said spring means whereby to alternately pressurize and depressurize said chambers.

4. The invention set forth in claim 3 including: a. a layer of compressible material disposed on said platen means, the said fluorescent screen which is on the platen side of said film path being adhered to said layer.

5. The invention set forth in claim 1 wherein: a. said pump means is stationary relative to said film compression chamber in said housing means, and b. said conduit means is a flexible hose.

6. In diagnostic x-ray apparatus including a spot film device located on a side of the patient-supporting surface of an x-ray table which is opposite to the side on which an x-ray source is located, stationary fluoroscope means positioned to receive an x-ray image from a subject supported on the table and to convert said x-ray image to an image which may be visualized, said spot film device being selectively movable between a storage position and an active position in a plane between said fluoroscope means and the table top, an exposed film cassette on one side of said transportable means and an unexposed film cassette on the other side thereof, means on said transportable means adapted to selectively convey film from one cassette to the other, the improvement in said spot film device comprising: a. a movable gas operAted film compression chamber, said chamber having a diaphragm sealingly installed in a side thereof, said diaphragm being distensible toward a film path in response to gas pressure being applied to the interior of said chamber and said diaphragm being retractable when said pressure is relieved, b. platen means in substantial parallelism with said diaphragm means and defining said film path therewith, c. means for selectively applying and relieving pressurized gas to and from said film compression chamber, whereby to alternately press a film against said platen means and to release the film for conveyance, d. relatively stationary pump means comprising a chamber and a flexible pump diaphragm means sealingly enclosing said chamber, e. spring means biasing said pump diaphragm means in one direction that effects a certain volume and pressure within said chamber, f. electromagnetic means operatively coupled with said pump diaphragm means to urge said pump diaphragm means in an opposite direction and thereby effect a different volume and pressure in said pump chamber, g. conduit means communicating between said film compression chamber and said pump chamber, and h. said electromagnetic means being selectively energizeable to oppose said spring means whereby to alternately pressurize and depressurize said chambers.

7. The invention set forth in claim 6 including: a. x-ray fluorescent screens attached to said platen means and said diaphragm means, respectively.

8. The invention set forth in claim 6 including: a. a thin flexible back-up plate means adhered to and distensible with said diaphragm means and having an area slightly less than said diaphragm means and being slightly convex toward said film path, and b. a fluorescent screen adhered to said back-up plate means.

9. The invention set forth in claim 6 including: a. a compressible layer adhered to said platen means, and b. an x-ray fluorescent screen adhered to said layer.