US2593526A - X-ray shutter - Google Patents

Description

Ap 1952 s. BELL ETl'AL 2,593,526

X-RAY SHUTTER Filed June 23, 1950 2 SHEETS-e-SHEET l INVENTORS. LOClLf/V 5.5ELL, TRUMAN W MAL 71 5K Patented Apr. 22, 1952 Locklin Savage Bell, Hales Corners, and Truman. Winner. Maltby,. West Allis, Wis., assignors to General Electric Company, a corporation of New'York Applicationiune 23, 1950, Seria1-.No., 169584;? Claims. Cl. 250-105) The present invention relates in general to X-ray protective shutter means, and has moreparticular reference to a. shutter construction. for multiple window X-ray tubes of the sort commonly provided for diifraction analysis procedures, as inspectrogoniometer apparatus.

An important object of the invention is to provide a simple, efficient shutter construction for normally closing the X-ray emission window of an X-ray; tube. in fashion substantially prevent.- ing X-ray emission, and readily operable to. uncover thewindow to permittheexit therethrough of X-raysfor useful purposes.

Another important object is to provide an X-ray tight shutter for X.-ray. tubes of ,thecharacter mentioned, and adapted for operation in conjunction with thecollimator tube. of spectrogoniometer apparatus, whereby the shutter may normally operate to prevent the escape of X-rays from the X-ray tube when closed, said shutter being operable for thereception of a collimator, tube in position allowing the escape. of Xi-rays fromtheX-ray tube only through the positioned collimator tube; a further object being to arrange the. shutter. to accommodate variations,

within limitations, in the alinedposition of. the

collimator. tube.

Another important object is to provide an X-ray shutter structureof the character men,- tioned, comprising a shutter, assembly adapted for removable attachment on. an X-ray tube,.

whereby the shutter structure may be. readily transferred from a tube, attheend. oftheservice life of the tube, and applied upon a replacement. tube.

Another important object of. the invention. is to provide shutter apparatus for multiple window X-ray tubes, comprising an individual shutter assembly for, each window the several assemblies being adapted to interfit each. withanadiacent assembly, to form an Xeray opaque sheath. about the X-ray emissionportionsof the tube.

Another" important. object is to. provide. an X-ray shutter structure comprising, amounting plate adapted for attachment on an X-ray tube at the. ray emitting window thereof, a block interflttingl'y assembled onthemounting plate and formed with an opening. for the transmission.

of X-rays therethrough, including a socket for the reception of a. collimator tube in alinement with said opening, said block being movable within limits on themounting plate in position overlyingthe emission window. ofthe X-ray tube, whereby to accommodate variationsin the alinement. ofthe collimator tube, and. a spring pressed" shutter plate. on said block and normally, urged into position covering said opening, and. socket.

The foregoing and numerousother important objects, advantages, and inherent functions, of

the invention will become apparent as the same is more fully understood from the following description. which,. taken in. connection with the.

accompanying drawings," discloses a preferred embodiment of the invention- Referring to the drawings;

Fig. 11 is a. perspective view of spectrogon'iometer apparatus containing anX ray tube fitted with shutter means. embodying the present invention;

Fig. 2. is any enlargedperspective view of the X-ray tube. and theshutter means;

Fig. 3- is anexploded perspective view of, the

shutter means. and the X-rayv emitting. portions Fig. 11 is a top view of" a collimator tube mounting socket and X-raywindow formed in" the block element'illustrated in Fig.6; and

Fig. 12 is a sectional view taken" substantially along the line |2l2 in Fig. 7. I

To illustrate the-invention, the-drawings -show spectrogoniometer apparatus I-3-, comprisinga frame forminga mountinglt for amX-raytube:

l5, acentralj turnable-pedestal mounting. It for supporting a specimen in positionto beexposed to. Xerays A emitted from the tube l 5 for spectre analysis; and'isuitable detector apparatus; l'l'car ried' in a frame 3 turnab'le with" respect toithe axis. of'rotation of the specimen-mounting pedes- 122;]; I6.

It should be understood that a specimen 'may be analyzed for itsXeray difiraction characteristics' by adjustably turning thesameat the axis of the support pedestal I6, and" by adj ustably turning the detector. equipment" l1 about said axis and observing or recording the resulting spectrographic data by means of'th'e detecting;

apparatus, while applying: X-rays. upon the pedestal mounted specimen. To this end, the X-ray tube I is supported in the mounting M in position such that X-rays, emitted from the tube [5, will be directed toward the specimen under examination. Accordingly, the tube I5 is supported in fixed position to emit X-rays radially inwardly toward the axis of the pedestal lb. Suitable graduated scale means may be provided for indicating the relatively turned or angular position of the pedestal l6 about its axis, and the position of the detector equipment IT.

The X-ray tube I5 may comprise a sealed envelope including a glass portion is at one end, and a metal portion 28 at the other, said metal portion comprising a hollow sleeve of rectangular sectional configuration sealed to the glass portion H], as at 2|, said metal sleeve having a preferably cylindrical bearing portion 22 formed thereon, adjacent the seal 2|, and adapted to fit into a support clamp in the pedestal it, whereby the tube maybe turnably adjusted in said support clamp and secured in adjusted position with any desired one of the several sides of the sleeve portion 20 facing inwardly toward the axis of the pedestal l6.

The end of the sleeve 29 remote from the hearing portion 22 is closed by means of a cover 23 suitably sealed upon the end of the sleeve, and an anode target is disposed in the sleeve inwardly of said cover in position for bombardmcnt, within'the sleeve, by electrons emitted from a suitable cathode supported on the glass portion 19, in position within the sleeve 20 spaced from and facing said anode target. The walls of the sleeve 20 inwardly of the end cover 23 may be formed with X-ray transparent windows 24 disposed opposite the anode target, through which said w.ndbwsX-rays generated at the target, as a result of electron bombardment thereof, may be transmitted outwardly of the tube. As shown, the sleeve 20 is provided with three such X-ray transmitting windows, there being a window in each of three of the four sides of the sleeve 20. The windows are preferably centered in the sides of the sleeve. The fourth side of the sleeve is not provided with a window, but metal tubes 25 extend along said side from the bearing 22 at the medial portionsof the tube to the end cover 23, said tubes being connected through channels in said cover with a cavity in heat exchange relationship with the anode target, whereby cool ing fluid-may be circulated through said tubes into heat exchange relation with the target, to

aid in cooling the same. The tubes may be retained upon the wall of the sleeve 28 by means of a cover plate 26.

din-order to confine the X-ray beam against dissipation laterally thereof after the rays have passed outwardly of the sleeve through a window 24, the beam is directed through a so-called collimator tube 21, the same comprising a tube of preferably X-rayopaque metal. In the spectrogoniometer apparatus, the collimator tube 21 is mounted on the main frame or table in position extending radially of the axis of the specimen pedestal It. The collimator tube is supported in such. position on a suitable bracket. In this connection, it should be understood that spectro analysis requires the substitution of X-ray generating tubes in the apparatus, depending upon the nature of the specimen being examined. This requirement, together with the circumstances that a multiple window tube may be adjusted in the support [4 to present any selected one of its windows in position to apply X-rays upon the specimen, results in possible limited mis-alinement of the collimator tube 27 with respect to the window 24.

It is highly desirable, if not essential, for the sake of protecting operating personnel against irradiation, to provide means for preventing X-ray emission from the tube except through the collimator tube 21, when the apparatus is in operation for spectro analytical purposes. To this end, the present invention contemplates the provision of relatively simple and inexpensive, yet highly effective, shutter structure 28 adapted for attachment on the tube 15 at the X-ray emitting portions thereof, said structure normally enclosing said X-ray emitting portions for the substantially complete prevention of X-ray emission from the tube. The shutter means, however, is readily operable to allow application of a collimator tube to any of the windows 24, in fashion precluding the escape of rays outwardly of the collimator tube at the X-ray window abutting end thereof, said shutter means being formed to accommodate any slight variation in the alined position of the collimator tube, and

operating automatically to close up the shutter means against X-ray emission instantly upon removal of the collimator tube from window abutting position.

To this end, the shutter structure 28 may comprise a shutter assembly 29 for each of the X-ray Each of the assemblies 2e emission windows 2 may conveniently comprise a mounting plate or frame 39, formed with a central, preferably rectangular opening 3i and adapted preferably for and some of said side edges may be notched or removable attachment on the wall of the sleeve 20 in position overlying a window opening 24, with the window opening disposed preferably at the central axis of said opening adjacent one end thereof; a block member 32 supported on the frame for limited movement in the opening 31, said block having an opening 33, therein, in alinement with the window 24, and a collimator tube end seating socket 34 surrounding said opening 33; and a shutter plate 35 shiftably 1 mounted upon the block 32 and normally urged thereon, as by means of a spring 35, into position normally covering said opening 33 and socket 3 3, said shutter plate 35 being retractable on the block member 32 against the influence of the spring 35 to uncover said seat socket 34 and the opening 33 to permit application of the end of a collimator tube in the socket 34, in alinement with the opening 33 and the window opening 2 of the X-ray tube on which the shutter structure is mounted.

The mounting member 3!! may comprise a rectangular frame sized to cover the entire side wall portion of the sleeve 28, containing a window 24. The member may be formed with openings 3's, outwardly of the central opening 3!, for the accommodation of fastening screws for the attachment of the member on the sleeve 26. The side edges of the plate, also, may be beveled, as at 38,

undercut, as at 33, while others may be truncated, as at 43, to interfittingly engage in a notched portion 39 of the mounting plate of a shutter assembly adjacently mounted on the sleeve 23. Thus, where the shutter structure is provided for attachment on a sleeve 26 of rectangular section, in which cooling pipes 25 extend along a windowless side wall of the sleeve, shutter structures, having mounting plates 30a formed with undercut notches 39 in the opposite side edges thereof, may be provided for attachment on the sleeve walls immediately adj ace'n-t the windowless wall, whereby the projecting side edges of the cooling tube cover plate 26 may extend in said grooves 39, along one-side of said plates 30a, as shown clearly in Fig. 90f the drawings.

A "shutter assembly, having a mounting plate 30?) formed with truncated side edges 40, maybe provided for application upon the remaining side wall of the sleeve'20 opposite fromthe'windowless side wall, so that said truncated edges 40 of the mounting plate may extend interfittingly in the grooves 39, along the Opposite sidesof the plates 30a, as also shown in Fig. 9 of the drawmgs.

The plate 26 and the plates 38a and 3%, as well as the blocks 32 and 'shutterplates 35, are preferably formed of X-ray opaque material, such brass, which may be nickel plated ii desired. and the block members 32 are interfitted with the mounting plates 30 in such fashion as to nose the central openings 3| against X-ray penetration therethrough. As a consequence, theseveral plates 33 and the shutter structure thereon form, with the cover plate 26, a substantially X-ray Itight band about the X-ray emitting sleeveportions of the'X-ray tuba-by virtue of the interfitment of the abutting edges of the plates 26 and 3 0. The end cover 23 is'also preferably formed ofmateriaIsubstantially opaque to X-rays and. has edges 4 projecting outwardly beyond the outer surfaces of the side walls of the sleeve 20, whereby to overlie the outer end edges of the plates 26 and 30 and thus prevent the escape of X-rays where the plates 23 and 30 so abut the projecting edges of the end plate 23. a

Each of the plates 3i| is preferablyformed with a relatively thin web 42 therein at one end of the opening-3|, and each plate-is preferably undercut in its inner or sleeve facin surface, at the opposite'end of the opening 3|, to form a seat 43 for a retaining plate M.

The block member 32 preferably comprises an elongated, generally rectangular bar of substantial'thickness at one end, and undercut at the otheren'd to provide a portion of lesser thickness. The opening 33 is formed adjacent the end of the bar in its relatively thick portion, said opening being preferably elongated in a direction transversely of the bar. The collimator tube end receiving socket 34 encircles the opening 33 and opens upwardly in the bar 32. The upper surface o'f'the bar is preferably formed toprovide a slideway for slidingly receiving the shutter slide 35, said slideway being closed at the relatively thick end of the m'embe r 32 andopen at the opposite end, said 'slideway being defined by an inturn'ed lip-orrib 45 extending atthe margin of said slideway, "including the closed end thereof. This inturned lip 45 is adapted to slidingly engage and interfit in a correspondinggroove 36 formed in theshiitter member '35 in the marginal side edges arrears end ed'gethereof.

elongated slot 4'! preferably formed in the relatively thinnerpor'tions "of the her 32 from adjacent the end thereof to the medial portions ofthe bar 32, s'aidslot being adapted to accommodate the "spring 36-, which is mounted at one end on "an anchor pin 48'disposed in the slot medially of the bar 32, the other end of the spring 36 being attached to a projection 49 on the underside of the slide member 35, said projection 49 preferably comprising a screw member adapted to be attached on the slide member after the same has been mounted inthe slideway of the member 32. The spring operates in tension "to normally urge the slide member 35 into relatively closed position on the member 32, in which the distal-end of the slide member snugly engages in the closed end of the slideway in position covering the socket 34 and the X-ray transmitting opening 33. said slide being retractable at Will in the slideway to uncover said socket and opening.

The member 32 is formed with outwardlyezv tending lateral flanges 50 at and along the lowermost side edges of its relatively thick portion,

through which the opening 33 formed. The

end of the bar, also, is formed with a transverse slot 5| extending immediately above the flanges 5D, said slot being adapted to slidingly receive and interfit with theweb 42 of the mounting plate. The opening 3| of said mounting plate isslightly wider between its lateral edges than the widthof the bar member 32. Said opening 3|, also, between the web 42 iand'the remoteend of said'opening, is slightly larger than the relatively thickpor tion of the bar 32. Accordingly, said bar may beinterfittingly assembled on a plate 30 by introducing the relatively thin end of the bar 32 through the opening 3| from the under side of the plate 30. The relatively thinend of the'm'e'rnber 32 may thus be drawn upwardly through the opening until the relatively thick portion of the member is alined with the opening 3|,whereupon the member 32 may be rocked into position "to aline the slot 5| with the web 42.

In such position, the flanges 50 will underlie the portions of the plate 30 defining the lateral edges of the opening3|,"which said portions may be undercut, as at 52, to slidingly accommodate and interfittinglyreceive the flanges 5|] behind the plane of the lower surface of the plate 30. Thereupon, the member 32 may be moved on the plate 38 in a direction to interfittingly receivethe web 42 within the slot 5|. The member 32 may then be secured in mounted position on the plate 30 by applying the retaining plate $4 in its mounting socket 43, the same being secured in position as by means of fastening screws 53, applied through the mounting plate 30 from the upper or outer face thereof.

The mountingplate M, when so attached, provides an abutment for the shoulder defining the end of the relatively thick portion of the bar 32, at its junction with the relatively thin portion of saidbar, so that the bai- 39 may not thereafter, save by detachment of the member 4'4, be moved to a position in the opening 3| disengaging the web 42 from the notch 5|.

-From the foregoing, it will be seen that the member 32 is mounted for limited longitudinal and lateral movement on the mounting plate 30, but tha't the opening 3| is substantially closed by the member 32 regardless of the'longitudinally or laterally adjusted position of the member on the plate, the opening 3| being so closed by virtue of the interfitment of the web 42 in the slot 5|, and by the overlapping relationship'of the flanges 50 w'ith 're'spect to thesi'de edges of the opening 3|. It' will'be hotedalsojthat no portion of the menu"- berezge ten'ds beyondthe plane of the lower surface or the plate 31],when mounted thereon, so that when said plate 36 is attached on the sleeve 2i|;th'e' member 32 will beheld on said sleeve with the opening 33 in alinement with the X-ray emittingwindow24, the member 32 being freely adjustable laterally and longitudinally on the sleeve Within limits defined by said side edges of the opening 3|, the web 42 and slot 5|, and the retaming plate 44. Such adjustment is sufiicient to accommodate slight axial eccentricity of :a

awam

collimator tube to which the X-ray tube may be applied, for the delivery of X-rays through the shuttered window '24 and into the collimator tube through an end thereof disposed in the socket 34 in alinement with said window.

If desired, a disk or plate 35 of material such as tantalum. relatively highly resistant to X-ray transmission therethrough, may be inserted in the under side of the shutter plate 35 in position to cover the opening 33 when the plate is in closed position on the block 32. Such an insert permits use of a relatively thin shutter plate 35.

A feature of the present invention resides in the utilization of the shutter plate carrying block 32, relatively shiftable on the frame 39, which not only accommodates mis-alinement of the collimator tube when inserted in the pocket 34, but

also accommodates the collimator tube in the various radial positions of adjustment in which it may be disposed in the spectrogoniometer.

Since the distance from the X-ray emission ports 24 of the X-ray tube to the end cover 23 is of necessity limited, because of radial movement of the spectrogoniometer, the stackedslide arrangement of the present invention utilizes this space to best advantage as compared with a single slide shutter, which would have to project beyond the end cover 23, thereby interfering with the functioning of the spectrogoniometer. The present invention further not only provides a direct cover for preventing direct radiation through the ports 24 when the shutter plates 35 are in closed position, but the interfltting members 39, 32, 35, and the marginal edges El of the member 23, overlap to such a degree and in such fashion as to require at least two right angle turns in all possible X-ray leakage paths, so that such leakage radiation as may occur comprises tertiary or weaker than tertiary radiation.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A shutter structurefor X-rays and the like comprising a mounting frame, member defining an opening, a ported member on said frame member in said opening, said ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said ported and frame members having interfitting portions allowing limited relative movement thereof to adjust the position of said seat with respect to said frame member, and a shutter member shiftableon said ported member between port covering and uncovering positions.

2. A shutter structure for X-rays and the like comprising a mounting frame member defining an opening, a ported member on said frame member in said opening, said ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said members having interfitting flange means closing said opening around said ported member while allowing limited relative movement thereof in said opening to adjust the position of said seat with respect to said frame member, and a shutter member shiftable on said ported member between port covering and uncovering positions.

3. A shutter structure for X-rays and the like comprising a mounting frame member defining an opening, a ported member on said frame member in said opening, said ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said opening having rectangular configuration and said frame having a web portion at an end of said opening, said ported member comprising a rectangular block having a transverse slot at an end thereof for slidingly receiving said web, abutment means attachable on said mounting member, at the other end of said opening, in position to limit movement.

of the block in a direction to disengage the web from the slot, and a shutter member shiftable on said ported member between port covering and uncovering positions.

n (l. A shutter structure for X-rays andthe like comprising a mounting frame member defining an opening, a ported member on said frame member in said opening, said ported member having, a ray port formed therein and a collimator tube end seat surrounding said port, said ported member comprising a block having laterally projecting flange means slidably underlying the frame memher at the sides of the opening to close the same around the block while permitting limited movement of the block in the opening to adjust the position of said seat with respect to said frame member, and a shutter member shiftable on said ported member between portcovering and uncovering positions.

5. A shutter structure for X-rays and the like comprising a mounting frame "member defining an opening, a ported member on said frame member in said opening, said ported member having a ray port formed therein and a collimator tube and seat surrounding said port, said ported member comprising a block sized to fit loosely in said opening and mountable therein from one side of the frame member, projecting flange means on the block in position to slidingly underlie the frame at the sides of the opening to close the same around the block, interengaging means on said block and frame member for holding the block in mounted position on the frame member, and

a shutter member shiftable on said ported member between port covering and uncovering positions.

' 6. A shutter structure for X-rays and the like comprising a mounting frame member definingan opening, a ported member on said frame member in said opening, said ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said opening hav ing rectangular configuration and said frame member having a web portion at one end of the opening, said ported member comprising a rectangular block having a transverse slot at one end thereof for sliding interfitment with said web, said block being sized for assembly in said opening from the underside of the frame, into position registering the web with said slot, lateral flanges on and projecting outwardly of said block below said slot in position to underlie and engage flange seats on the frame at the sides of the opening, whereby the web and slot may be slidingly interfitted by moving the block on said frame member to slide said flanges on said flange seats, a retaining plate mountable on theiframe member in posi tion extending in the end of said opening remote from said web to limit movement of the block on the frame member in a direction to disengage the web from the slot, said ported member bein formed with a slideway providing a shutter seat having an open andclosed end, an inturned shutthe closed end of said shutter'seat,.said port and collimator tube end seat opening in said shutter seat, adjacent the closed end thereof, a shutter member in said seat and having a groove in its side edges and an end edge thereof for receiving said lip, and spring means connected between said portedand shutter membersnormally urging said shutter memggr toward closed position in said seat overlying said port and collimator tube end seat therein, said spring lying in a pocket formed in saidshutter seat.

7. The combination, with a ray source having an envelope portion formed with a ray transmitting window, of a shutter structure for controlling ray emission outwardly of said envelope portion comprising a mounting frame member defining a central opening, means to removably secure said frame member on said envelope portion around said window, a ported member havin ray port formed therein and a' collimator tube end seat surrounding said port, said members having interfitting portions securing said ported member on said frame member with said port in alinement with said window, said interfitting portions affording limited relative movement of said members to adjust said seat laterally of said window in all radialdirections, and a shutter member shiftable on said ported member between port covering and uncovering positions.

8. The combination as set forth in claim 7, wherein said interfitting means comprises flange means on said members and having relative sliding engagement to close said opening around said ported member while allowing limited relative movement thereof in said opening.

9. The combination as set forth in claim 7, wherein said opening has rectangular configuration and said frame has a web portion at an end of said opening, said ported member comprising a rectangular block having a transverse slot at an end thereof for slidingly receiving said web, and abutment means attachable on said mounting member, at the other end of said opening, in position to limit movement of the block in a direction to disengage the web from the slot.

10. The combination as set forth in claim 7, wherein said ported member comprises a block sized to fit loosely in said opening and mountable therein from one side of the frame member, projecting flange means on the block in position to slidingly underlie the frame at the sides of the opening to close the same around the block, and interengaging means on said block and frame member for holding the block in mounted position on the frame member.

11. A shutter structure for a ray source having an envelope portion provided with a plurality of spaced apart ray transmitting windows, comprising a shutter assembly for each window, said assemblies being adapted for adjacent mounting on said envelope portion, each said assembly comprising a mounting frame member defining a central opening, means to removably secure said frame member on said envelope portion around a said window, a ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said members having interfitting portions securing said ported member on said frame member with said port in aline ment with said window, said interfitting portions afiording limited relative movement of said members to adjust said seat laterally of said window in all radial directions, and a shutter member shiftable on said ported member between port -.covering. and uncovering positions, the lateral edges of a said mounting frame member being formed for interfltti-ng engagement with the abutting edge. of the mounting frame member of a shutter assembly. adjacently mounted on said envelope.

12. A shutter structure for a ray source having a sleeve-like envelqpe portion of rectangular sectional configuration providing adj acently disposed fiat sides formed with a ray transmitting window in each of several of said adjacently disposed sides, said shutter structure comprising a shutter assembly foreach of said windows, said assemblies being adapted for mounting each on, a said fiat side, each said assembly comprising a mounting frame member definin a central opening,

means. to removably secure said frame member on a flat side of said envelope portiona'round said window, a ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said members having interfitting portions securing said ported member on said frame member with said port in alinement with said Window, said interfitting portions aifording limited relative movement of said members to adjust said seat laterally of said window in all radial directions, and a shutter member shiftable on said ported member between port covering and uncovering positions, said mounting frames having lateral edges extending at and outwardly of the lateral edges of the flat sides on which mounted, the lateral edges of a said mounting frame member being formed for interfitting engagement with the abutting edge of the mounting frame member of a shutter assembly adjacently mounted on said envelope.

13. An X-ray tube having an envelope portion formed for X-ray emission through said envelope portion, a shutter structure for controlling such X-ray emission and. comprising a mounting frame member defining a central opening, means to removably secure said frame member on said envelope portion, a ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said members having interfitting portions securing said ported member on said frame member, said interfitting portions affording limited relative movement of said members to adjust said seat laterally of said mounting frame in all radial directions, and a shutter member shiftable on said ported member between port covering and uncovering positions.

14. An X-ray tube having an envelope portion formed with an X-ray emission window therein, a shutter structure for controlling X-ray emission outwardly of said envelope portion comprising a mounting frame member defining a central opening, means to removably secure said frame member on said envelope portion around said window, a ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said members having interfitting portions securing said ported member on said frame member with said port in alinement with said window, said interfitting portions aifording limited relative movement of said members to adjust said seat laterally of said window in all radial directions, and a shutter member shiftable on said ported member between port covering and uncovering positions.

15. An X-ray tube having an envelope sleeve portion formed with a plurality of X-ray emission windows therein, a shutter structure for controlling X-ray emission outwardly of said envelope portion comprising mounting frame means formed for removable attachment on said sleeve portion at said windows, said frame means defining an opening at each of said windows, a ported member on said frame means in each of 'said windows, each ported member having a ray port formed therein and a collimator tube end seat surrounding said port, said: frame means and ported members having interfitting portions securing the ported members on said frame means, with said ports in alinement with said windows, said interfltting portions allowing limited relative movement of the ported members on the frame means to adjust said seats laterally of said windows in allradial directions, and a shutter member on each ported member and shiftable thereon between port covering and uncovering positions.

LOCKLIN SAVAGEBELL.

TRUMAN WINNER MAL'IBY.

12 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,094,103 Horsley et al. Sept. 28, 1937 2,168,801 Lee et a1.v Aug. 8, 1939 2,181,620 Haupt 'Nov. 28, 1939 2,331,586. Waisco Oct. 12, 1943 2,430,969' Young Nov, 18, 1947 2,453,798 Kloos Nov. 16, 1948

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