US2901632A - Photo tube energizer - Google Patents

Description

Allg- 25, 1959 R. J. sTAvA ETAL 2,901,632

PHOTO TUBE ENERGIZER Filed sept. s, 1953 5 sheets-sheet 2 Allg. 25, 1959 R J. STAVA ETAL 2,901,632

PHOTO TUBE ENERGIZER Filed Sept. 3. 1953 5 Sheets-SheOt 3 IN VEN TOR.

Aug- 25, 1959 R. J. sTAvA ETAL PHOTO TUBE ENERGIZER 5 Sheets-Sheet 4 Filed sept. 3. 1953 we H United States Patent() M' PHOTO TUBE ENERGIZER Robert J. Stava, University Heights, Walter G. Reininger,

Cleveland Heights, and Gunter G. Wilkens, East Cleveland, Ohio, assignors to Picker X-Ray Corporation, Vgatlei Mfg. Div. Inc., Cleveland, Ohio, a corporation o o Application September 3, 1953, Serial No. 378,368

1S Claims. (Cl. Z50- 95) This invention relates to an apparatus for controlling radiant energy and more particularly to a device for guiding a directed beam of radiant energy in a confined path to an energy responsive control element displaced from the directed beam.

The utilization of radiant energy in a given application may be readily controlled by means of a radiation responsive control element whose response is related to the radiant energy in a predetermined manner. For example, in an X-ray apparatus a radiation sensitive element may be utilized to control the time exposure of radiographic film in response to energization by a predetermined amount of the X-rays. the radiation is directed towards a subject and the radiographic film and radiation sensitive element are operatively interposed in the directed path of the radiation. In this and other applications, space and operating limitations make it desirable that the radiation responsive element be physically positioned at some location displaced from the directed path of the radiations. Accordingly, one of the objects of this invention relates to a reduction in the over-all table height of an X-ray apparatus.

A further object of this invention relates to the provision of a device for guiding radiant energy from a directed path to a radiation responsive control element displaced from such path.

A still further object of this invention is to permit location of a radiation responsive control element in relation to the source and other operative members of an X-ray apparatus to prevent interference and operating difficulties.

Briefiy, in accordance with this invention there is provided a guide for intercepting a directed beam of radiant energy and guiding such energy in a confined path towards a displaced radiation responsive control element. The guide embodies a solid light confining member which is positioned to accept fluorescent illumination from a screen intercepting the beam for guided direction towards a photo-sensitive control element displaced from the directed path of the beam. The accepting surface of the guide member is preferably roughened to improve the sensitivity and overall transmission eiiiciency, and the physical configuration of the guide is such as to permit a reduction in the space requirements of the apparatus.

In the drawings,

Fig. 1 illustrates an X-ray apparatus embodying the invention;

Fig. 2 is a view taken along the lines 2-2 in Fig. l;

Fig. 3 is a view taken along the lines 3 3 in Fig. 2 and showing in cross section the energy guide of this invention;

Fig. 4 is a partial View taken along the lines 4 4 in Fig. 1 illustrating the energy guide;

Fig. 5 is an enlarged view of a modified portion of the cross section of Fig. 3;

Figs. 6, 7 and 8 are partial sectional views of different embodiment of the energy guide and screen; v

In an application of this type, Y

Patented Aug. 25, 1959 Fig. 9 diagrammatically illustrates a spot-film type of X-ray apparatus;

Fig 10 is a top view of the iiuoroscopic screen arm of the apparatus in Fig. 9;

Fig. 1l diagrammatically illustrates a section taken along the lines 11-11 in Fig. 10;

Figs. 12 through 14 are sectional views diagrammatically illustrating modified arrangements of the apparatus of Fig. 11;

Fig. 15 is a view taken along the lines 15-15 in Fig. 14.

Referring now to the drawings the invention is shown in an exemplary environment of an X-ray apparatus which in Fig. l embodies a table for supporting a subject for exposure to a source of X-ray radiation in the form of an X-ray tube head 12 which is operatively disposed above the table by means of a supporting column 13. The X-ray tube head 12 and supporting column 13 may be positioned for movement along the table to enable the operator to scan different areas of the patient. Whenever such an area is located, it may be observed through a fluoroscopic screen, not forming part of this invention and, therefore, not shown, or it may be exposed to a radiographic film for subsequent analysis. The radiographic film is usually carried in a cassette 15 which is preferably positioned within a reciprocating bucky carriage 16 in a well-known manner.

As best shown in Fig. 1, the bucky carriage and cassette are carried within the top of the table, adjacent the subject, for alignment with the directed source of X-ray radiation. As hereinbefore noted, exposure of the radiographic film to the source of X-ray passing through the subject may be controlled by a radiation responsive control element which may be positioned to intercept the path of the X-rays as they pass through the subject and radiographic film. Heretofore, the control element and its housing have been located beneath the bucky carriage or on an arm adapted to be positioned into the path of the X-ray beam under the carriage. However, space and operating limitations render it desirable that the control element be located in some position displaced from the directed path of the X-rays. The feasibility of such displacement, however, depends upon the ability to transfer the directed path of X-rays towards the displaced control element.

As shown in Figs. 1 and 2, this has been accomplished by providing guide 20 indicated by dotted lines, which has the characteristic of intercepting the normal path of the radiated beam and directing it in a confined path towards the displaced control element 25.

The energy guide 20 is shown in greater detail in Figs. 3, 4 and 5 and preferably embodies a solid elongated member made of a material having a high degree of transparency to light and provided with selected highly polished surfaces to coniine the light within the body of the guide for direction along its length. Various materials, such as quartz, have the desired characteristics and certain thermo-plastic materials, particularly polyrnerized methylmethacrylate resin, otherwise commonly known to the trade as Lucite, and the thermo-plastic acrylic (methylmethacrylate) resin, otherwise known as Plexiglas, have an almost perfect transparency to light so that, when highly polished, any light accepted by the material remains within the body of the material even to the extent of following the body around limited turns and bends.

To use such a guide it is necessary to convert the radiated X-ray energy into suitable light energy for acceptance by the guide body. This may be accomplished by placing a iiuorescent screen 30 in the path of the radiated X-ray beam adjacent the accepting surface of the guide 20 as shown in Fig. 3. A more efficient guide may be attained by providing two uorescent screens in Contact with the intercepting portion of the guide 20 as best shown in the enlarged section of the guide in Fig. 5 of the drawings. One screen 30 in contact with the upper surface of the guide and another screen 31 in Contact with the lower surface of the guide.

We have found that when a fluorescent screen is placed in this manner in contact with the guide 20 there is a tendency that the light emitted closer to the photosensitive element reaches that element with greater intensity than the light accepted by the farther portions of the guide 20. This results in a non-uniform sensitivity along the guide which provides unsatisfactory film exposures. Hence, the surface of the intercepting portion of the guide is preferably roughened or serrated in the manner shown in Figs. 3 and 5. This faceting of the intercepting surface acts to scatter the light within the guide in such a manner that the intensity of the light reaching the photo-sensitive element represents more nearly the average of that transmitted by the guide from the entire surface of the screen.

The faceting of the guide 20 is accomplished by providing grooves 21 having sharp saw-tooth edges with a high polish on both groove sides. We have found that the at or long groove side 22 should preferably be about 30 with respect to the longitudinal axis of the guide and that the short side 23 be vertical or transverse to the longitudinal axis of the guide. The faceting thus provides a plurality of opaque angles for scattering the accepted light energy from the iluoroscopic screen in the body of the guide.

Both the overall and average sensitivity along the guide can be further improved when using two screens by roughening the intercepting upper and lower surfaces adjacent the screens in staggered parallel zones as shown in Fig. 6 of the drawings. We have found that when using a guide approximately 1/4 thick and 18" long with a 41/2" square intercepting surface the best overall and average sensitivity was obtained by using 1/2" roughened Zones staggered as indicated above.

Further experiments and tests indicate that satisfactory results were obtainable with only one screen. In Fig. 7 of the drawings the screen is placed in contact with a smooth intercepting surface of the guide with a serrated opposite intercepting surface. The sensitivity of this arrangement was substantially the same whether the serrated intercepting surface was positioned towards or away from the X-ray source.

In order to approach the greater sensitivity available with two screens and yet permit the use of only one screen, we found that satisfactory results were obtainable by replacing one of the screens with a mirror as shown, for example, in Fig. 8 of the drawings. In this arrangement, the guide 20 is provided with a serrated intercepting surface facing the X-ray source and a screen 30 is placed in contact with the serrations while a mirror 40 is placed in contact with the smooth lower intercepting surface. `Satisfactory results were also obtainable with the guide reversed so that the mirror 40 was placed in contact with serrated intercepting surface of the guide. The arrangement and construction of the guide and screen thus takes advantage of the high degree of transparency of the material from which the guide is made to utilize the lightpiping effects of such material in a highly ei`n`cient manner. Light energy proportional to the radiated X-ray beam is thus accepted and directed in a confined path different in direction than the radiated beam and towards a displaced photo-sensitive control element.

In the preferred form, the light guide 20, along with the screen and mirror, if used, is masked by a light opaque material 35, which isolates the-light path from extraneous sources of light and aids in the transmission of-substantially all of the converted energy to the .photo-sensitive element. The mask of Fig. 3 has an opening 36 adjacent the photo-sensitive control element through which the directed illumination passes. For mounting purposes, the masked guide and screen are further mounted in a flat elongated housing 37 which is provided with suitable edge anges 38 that may be secured together about the guide and screen and mounted in the X-ray table in operative position relative to the X-ray tube head and to the radiographic film.

The photo-sensitive control element 25 is usually coupled to an electrical control circuit which actually carries out the function of terminating the exposure of the radiographic lm. The control circuit does not form part of this invention and is therefore not shown. However, the magnitude of the control current is proportional to the light emitted by the screen and, therefore, to the intensity of the X-rays that induced the light rays in the screen. The radiation actually intercepted by the screen varies with the density of the anatomical or other structure under examination and it is known that better control results are obtainable when the energy that reaches the screen or the control element is limited in some way to the particular rays passing through the region of interest.

Therefore, the apparatus illustrated in Figs. 1 and 2 includes a device for varying the radiation incident at the surface of the screen in accordance with the structure under examination. The device is best shown in Fig. 2 of the drawings in the form of a rotatable disc 50 carrying X-ray or light absorbent stops which may be selectively positioned beneath the film tray to define the X-ray beam or the area over which the photo-sensitive element is scanning and thereby to provide a plurality of differently dimensioned detectors.

Each of the stops in the disc assembly 50 are provided with differently arranged and sizes of openings depending upon the particular structure under examination, so that the area scanned is defined by the stops. The disc may be turned by means of an electric motor to select any particular opening for presentation to the primary beam.

The same objectives and advantages are obtainable regardless of the form the X-ray apparatus takes. Thus, as shown in Figs. 9 through l5 of the drawings, the guide 2) may be adapted for use with an apparatus having a spot film feature which is adapted for both fluoroscopy and radiography. A complete apparatus having such a device is shown generally in Fig. l0 and includes a base 60 which supports a tiltable table 61. An X-ray tube 62 is movably disposed for transverse movement within the table in a movable carriage 63 which is adapted to traverse the length of the table in conjunction with a column 65. The column 65 has a bracket 66 slidably mounted thereon, while an arm 68 is pivotally supported by the bracket.

The arm 68 is hollow and contains the spot film apparatus. A fluoroscopic screen and lead glass 69 is mounted over an opening in the top of the arm 68 for fluoroscopic examination. Provision is made for receiving and supporting a film cassette carrier or tray 70 and for moving the carrier from an isolated position to an active radiographic position within the hollow arm as shown by the dotted lines at 70A in Figs. l0 and 11. The mechanism for moving the tray 70 does not form part of this invention and therefore is not shown, however, suitable mechanism for automatically positioning the tray to permit film exposures either singly or serially is shown in a co-pending application tiled April 5, 1949, Serial No. 85,686 entitled X-Ray Apparatus.

In accordance with this invention, the radiation responsive timing control element 25 is mounted within the exposure end of the hollow arm 68 out of the path of the directed X-ray beam and a light guide 20 is operably positioned Within the hollow arm so that its light intercepting portion is adapted to be positioned into the path of the directed beam to accept and guide the corresponding light energy to the control element 25. The guide member-20 may be pivotally mounted within the arm 68 and coupled for movement to the film tray moving mechanism for automatic positioning into active position represented by the dotted lines at 20A in Fig. 10.

Such mechanism does not form part of this invention and, for convenience of illustration and description, is not shown, although, as 1nereinbefore noted, suitable mechanism for accomplishing such positioning is shown in the co-pending application, Serial No. 85,686. Thus, the guide member 20 shown in Figs. 10 and ll permits timing control of a film in any section of the cassette by proper orientation and positioning of the tray 70 and the guide 20.

In the preferred form shown in Figs. and 11, the guide 2G is diagrammatically shown located intermediate the cassette tray 70 and the visual fluorescent screen 69 so that it will not effect the'radiograph and is out of the way in liuoroscopy. Variations in the guide location and conguration are shown in greater detail in the sectional views of Figs. 12 through 15, the principal difference residing in the fact that the guide 20 is located between the cassette tray 70 and the X-ray tube 62. This latter arrangement is permissible if the liuorescent screen or coating 30 which is adjacent the intercepting portion of the guide is sufiiciently thin so that the effect on the radiograph would be negligable.

In Fig. l2 the guide member 20 represents a combination of previously discussed types in that it has opposite intercepting surfaces serrated in accordance with the form shown in Fig. 5 and is provided with a fluorescent screen 3@ and a mirror 40 in accordance with the form shown in Fig. 8. The complete guide member is attached to the cassette tray 70, rather than being independently pivoted as in Fig. 10, and thus, is positioned into and out of active radiographic position with the cassette tray. This form is limited to use with a single central cassette position, since the guide 20 must butt up against the control elernent 25 when in active position.

In order that the tray 70 may be variously positioned for exposure of different iilm areas, the arrangement shown in Fig. 13 utilizes a -tray which carries the liuorescent screen 3() on its underside and the guide 20 is xedly mounted in an enlarged sheet 75 of light transparent material `such as quartz or lucite, as best shown in Fig. 15 of the drawings. The sheet 75, having very little light filtration, will have little effect on the fluoroscopic image. The intercepting portion of the guide Ztl is limited in size to the desired pick-up area by masking the outside edges of the guide member with the light opaque material 35 which prevents the light from scattering through the edges throughout the sheet 75. Fluoroscopic indication of the junction can be eliminated by tapering the outside edges of the guide 20.

A modified form of this arrangement is shown in Fig. 14 in that the fluorescent screen 3i) is disposed directly adjacent the serrated intercepting surface of the guide and is thus fixed in position at all times during both fluoroscopic and radiographic examinations.

Thus, We have provided an energy guide for transmitting radiated energy from a directed path through a confined path to a radiation responsive control element which may be displaced away from the path of the directed oeam to permit a reduction in space requirements and in interference with other elements and operations of the overall apparatus.

We have shown and described what we consider to be the preferred embodiments of our invention along with similar modified forms and it will be obvious to those skilled in the art that other changes and modifications, particularly with respect to the configuration and arrangement of the guide body and the illuminating screen, may be made without departing from the scope of our invention as defined by the appended claims.

We claim:

l. A device for guiding light energy in a coniined path from a source of light to a light responsive element comprising, a solid guide member made of material having a high degree of transparency to light, said guide member having a light accepting portion and a light emitting portion displaced therefrom and including selected external surfaces adapted for guiding light in confined path from the accepting portion to the emitting portion at least one of said external surfaces of said accepting portion being serrated for coaction with another of said surfaces in a predetermined manner to ytransmit a maximum of light energy substantially uniformly from the entire accepting portion to the emitting portion.

2. In an X-ray apparatus having a directed beam of X-rays and a light responsive control element displaced from the path of the beam, means -in the path of the beam for intercepting and converting the X-rays into a proportional amount of light energy, a guide member made of light transparent material and forming a light transmitting path between said X-ray converting means and said control element, said guide member having a light accepting portion with a physical configuration for optically providing a substantially uniform transmission of a maximum of light energy to the control element.

3. In an X-ray apparatus having a directed beam of X-rays and a light responsive control element displaced from the beam, a fluorescent screen in the path of the beam for converting the X-rays to light, a solid light guiding member having a light accepting portion in the path of the beam and adjacent the screen and a light emitting portion adjacent the light responsive control element, said guide member having means for guiding the accepted light in a confined path from the accepting portion to the emitting portion to energize the light responsive control element, and said accepting portion having a surface configuration forming optical means for scattering the accepted light therein to provide a substantially`uniform transfer of light intensity from the entire exposed surface of the screen.

4. The apparatus of claim 3 wherein the accepting portion of the guiding member includes a surface roughened in a predetermined manner to form the optical means which coacts for substantially uniform transmission of a maximum of light form the accepting portion to the emitting portion.

5. The apparatus of claim 3 wherein the accepting portion of the guiding member includes external surfaces displaced from each other in the direction of the beam and wherein one of said surfaces is polished and the other is roughened in a predetermined manner to form said optical means, and the screen is operatively positioned adjacent the polished surface.

6. The apparatus of claim 3 wherein the accepting portion of the guiding member includes external roughened surfaces displaced from each other in the direction of the beam to form said optical means and wherein a liuorescent screen is operatively positioned adjacent each external roughened surface.

7. The apparatus of claim 3 wherein the accepting portion of the guiding member includes external surfac displaced from each other in the direction of the beam and wherein each surface is roughened as by serrations in parallel zones spaced from each other in the direction of light transmission to form said optical means, the zones on one surface aligned with the spaces on the other surface in the direction of the beam, and a fluorescent screen operatively positioned against each roughened external surface.

8. The apparatus of claim 3 wherein the accepting portion of the guiding member includes external surfaces displaced from each other in the direction of the beam and wherein at least one external surface is roughened as by serrations to form said optical means, and wherein a fluorescent screen is operatively positioned adjacent one external surface and a mirror is operatively positioned adjacent the other external surafce.

9. The apparatus of claim 3 wherein the fluorescent screen is spaced from the accepting portion of the guide member and wherein a masking member is operatively positioned for selective movement into the space to de- 7. iine and limit the amount of energy transmitted through the guide to the control element.

10. In an X-ray apparatus having a patient supporting table with a iilm carrier operatively disposed relative thereto for exposure to a directed beam of X-rays, a light responsive control element mounted adjacent one side of the carriage and displaced from the directed beam, a lightl opaque housing having a relatively narrow dimension in the direction of the table height mounted beneath the carrier and extending towards an open end at the side of the carriage adjacent the control element, a light guide member having a light accepting portion and a light-emitingting portion and including a physical coniguration of the accepting portion forming optical means for guiding maximum of light in a confined path from the accepting portion to the emitting portion, a fluorescent screen, said screen and guide member operatively disposed within the housing with the screen adjacent the light accepting portion of the guide in the path of the beam and the emitting portion adjacent the open end of the housing to guide the accepted light energy to the control element and thereby control the film exposure.

1l. In an X-ray apparatus having a patient supporting table top with a tilm carrier operatively disposed therein forA exposure to a directed beam of X-rays, a light responsive control element for controlling the film exposure mounted adjacent the carrier and displaced from the beam, a device mounted beneath the carrier to intercept and convert the X-ray beam to light, and optical means for intercepting the light from said device and guiding a maximum of light in a confined path towards the displaced control element, said optical means including a guide member having a light accepting portion with a physical configuration for providing a substantially uniform transmission of a maximum of light energy to the control element.

12. The apparatus of claim 11 wherein said last-mentioned means includes a solid light guiding member made of a material having a high degree of transparency to light and having selected polished surfaces with a roughened light accepting portion adapted to intercept the light from said device and a light emitting portion adapted to release the light at the control element.

13. In an X-ray apparatus having a hollow fluoroscopic screen arm operably supporting a movable lm tray adapted to be removably positioned into the path of a directed X-ray beam for exposure, a light responsive exposure timing control element mounted adjacent the exposure position of said tray and displaced from the directed path 0f the beam, a fluorescent screen in the path of said beam for intercepting and converting the X-ray beam to light, a light guiding member movably supported within the arm, said guide member having a light accepting portion and a light emitting portion and adapted to be positioned with the light accepting portion adjacent said iiuorescent screen in the path of the beam and the emitting portion positioned adjacent the control element when the tray is in the exposure position, said light accepting portion of the guide member having a physical configuration for optically providing a substantially uniform transmission of a maximum of light energy from the entire exposed surface of the fluorescent screen, and means coacting therewith to guide the accepted light in a confined path from the accepting portion to the emit ting portion to energize the control element.

14. The apparatus of claim 13 wherein said fluorescent screen and said guide member are operably carried by the tray and are adapted to be positioned for coaction between the control element and the X-ray beam consequent upon said tray being positioned into the path of the beam for exposure.

15. A light guiding device having a light accepting portion and a light emitting portion displaced therefrom and respectively adapted to receive and transmit light from an exposed iluorescent screen surface to a light re sponsive control member, said light accepting portion having a serrated configuration forming an optical sur face coacting therewith to transmit a substantially uniform intensity of light from the entire exposed surface of the fluorescent screen, and integral means for confining the transmitted light within the device for guidance toward the emitting portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,441,324 Morgan et al May 11, 1948 2,640,160 Collins et al. May 26, 1953 2,666,145 Eversole et al. Jan. 12, 1954 2,695,964 Schepker Nov. 30, 1954 2,840,716 Godbarsen June 24, 1958

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