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Publication numberUS2959680 A
Publication typeGrant
Publication dateNov 8, 1960
Filing dateMar 28, 1956
Priority dateMar 28, 1956
Also published asDE1062350B
Publication numberUS 2959680 A, US 2959680A, US-A-2959680, US2959680 A, US2959680A
InventorsDonald T Green
Original AssigneePicker X Ray Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Adjustable collimator for radiation therapy
US 2959680 A
Abstract  available in
Images(7)
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Claims  available in
Description  (OCR text may contain errors)

Nov. 8', 1960 2,959,680

D. T. GREEN ADJUSTABLE COLLIMAIOR FOR RADIATION THERAPY Filed March 28, 1956 7 Sheets-Sheet 2 Nov. 8, 1960 D. T. GREEN 2,959,630

ADJUSTABLE COLLIIVATOR FOR RADIATION THERAPY Filed March 28, 1956 7 Sheets-Sheet 3 ITTGRNE/J Nov. 8, 1960 I ,1', GREEN 2,959,680 I ADJUSTABLE COLLiMATOR FOR RADIATION THERAPY Filed March 28, 1956 '7 Sheets-Sheet 4 I 1-" INVENTOR.

banana 7, 604'! arm/num- Nov. 8, 1960 D. T. GREEN 2,959,680

ADJUSTABLE COLLIMATOR FOR RADIATION THERAPY 7 Filed March 28, 1956 7 Sheets-Sheet 5 INVENTOR. Dow/71.0 7? 6/95! Nov. 8, 1960 D. 1'. GREEN 2,959,680

ADJUSTABLE COLLIMATOR FOR RADIATION THERAPY Filed March 28, 1956 7 Sheets-Sheet 6 INVENTOR.

Domino 2' 6-0:!

Now.v 8, 1960 D. 'r. GREEN ADJUSTABLE COLLIMATOR FOR RADIATION THERAPY 7 Sheets-Sheet 7 Filed March 28, 1956 m T m m Dom no 7 6IN drawn/vi);

United States Patent C) ADJUSTABLE COLLHVIATORFOR RADIATION.

THERAPY r Donald T. Green, Cleveland, Ohio, assignor to Picker X-Ray Corporation, Waite; Manufacturing Division, Inc., Cleveland, Ohio, 21 corporation'offlhio Filed Mar. 2a, 1956, s Nb. 574,523 20 Claims. or. 250-105 This invention relates to improvements in an adjustable collimator for high'energy rays emanating from a source adapted for radiationitherapy.

An object of the present invention is to. provide means for controlling high energy rays of the type described by the use of a plurality of ray absorbing diaphragms, movably mounted and arranged progressively from the source outwardly, and mechanisms for holding the inner sides of an imaginary cone or polygonal pyramid whose.

longitudinal axis isthrough the source of high energy rays in all adjusted positions of the diaphragms, and more especially where the apex of said cone or pyramid is located approximately at said source.

A further object of the present invention is to provide an other-than-point source of high energy rays and to provide mechanisms for holding a series of movable diaphragms invarious adjusted positions, and in each of these positions the inner edges of these diaphragms are substantially aligned along the slanting sides of an imaginary cone or pyramid, the sides of which extend approximately through the lateral edges of the source,

A further object of the present invention is to provide. a plurality of ray absorbing diaphragms contained Within an expandable housing with the change in shape of the housing capable of moving one or more of the dia particularly, with an expandable frame for supporting said sets.

A further object of the present invention is to provide an adjustable collimator for high energy .rays. having ray absorbing diaphragms adapted to be'moved tochange the shape of the beam emanating from the, collimator, and having an indicator responsive to the positions of said diaphragms and actuated independent of the means for moving said diaphragms, whereby backlash'error is eliminated.

A further object of the present inventionis to provide a light source having a light beam coincidingwitha beam of high energy rays and to provide crossed cables in the center offsaid beams for. locating bysaid light beam the center of said ray beam duringuse.

A further object of the present invention is to provide an adjustable collimator for highenerg'y rays characterized by its structural simplicity,-compactncss of assem- Patented N ov. 8, 1 960 2. bly, efiicient ray. absorption of stray rays, ease ofopera: tion, wide range of beam shapes, sharp definition of the edges of the beam, minimum size housing for a given beam size, and smoothly fashioned housing contour even though the changing shape of the housing causes the changes in beamfshape.

Other features of this invention reside in the arrange ment and design of the parts for carrying out their appropriate functions.

Other objects and. advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set forth inthe appended claims.

In the drawings,

Fig. 1 is a side elevational view of the adjustable collimator of the present invention;

Fig. 2 is a bottom view taken along the line 2-2 of Fig. 1;

Fig. 3 is a vertical longitudinal sectional view taken along the line 33 of Fig. 2;

Fig. 3a is an enlarged top plan View of a modified form of diaphragm;

Fig. 3b is a vertical sectional view taken alongthe line 3b-3b of Fig. 3a;

Fig. 4 is a horizontal sectional view taken along the line 4 4 of Fig. 3 inside the bottom cover, below the expandable frame for supporting the diaphragms, and below the crossed cables;

Fig. 5 is a horizontal sectional view taken along the line 55 of Fig. 3 looking upwardly at the bottom most diaphragms, of the pile supported by the adjustable frame;

Fig. dis a horizontal sectional view taken along the line 66 of Fig. 3;

Fig." 7 is a bottom view similar to Fig. 4 but with. the

diaphragms in the expandedposition shown in Fig. 8;.

Fig; 8 is a vertical :sectionjal view taken along 'theline S8 of "Fig. 7 across corners of the collimator;

Fig. 9 is a horizontal sectional view taken along the line 99 of Fig.8;

Fig. 9a is a horizontal sectional view, similar to Fig. 9,

. of a modified form of corner. member and spring attachment;

Fig. 10 is a vertical sectional view taken generally along the line Ill-10 ofFig. S'Wi'th parts omittedl for clarity and other parts partially cutaway; I

Fig. 11 is a vertical sectional view taken generally along the line 11-' -11 of Fig. 3'with portions thereof partially cut away and with parts omitted'for clarity;

Fig. 12 is a sectionalview taken along the line 12--12 of Fig. 11; while Figs. 13 and 14 are pictorial representations of the shape andsize ranges of. high energy'raybeams that may be achieved by adjustment" of the collimator of the presently disclosed embodiment of my invention with Figs. 13 and 14 respectively disclosing the size ranges of beams of square and rectangular transverse cross sections.

Before theapparatus here illustrated is specifically described; it is to'be understood that the invention here involved is not limited to the structural details or arrangement of parts he're'shown sincej adjustable collimators embodying the present inventionlmaytakevarious rays where a diirect'ed beamof the rays'is required. The present inventionis directed to this problem. Wherever in the specification and" claims the term highienergy rays is used, or theequivalennit is' intended to include X-rays in the two to"three million volt region'rays from Cobalt, gamma rays or rays of a similar character or more penetrating than that. The present invention is described in connection with a Cobalt source.

The invention will be described with respect to the use of the rays from a therapeutic point of view for treating human beings, although it will be understood that the invention is useful for controlling high energy rays for any use whatever.

The mounting and control of the source forms no part of the present invention except insofar as it provides a fixed primary aperture in combination with the adjustable secondary aperture or opening in the collimator of the present invention. Any suitable mounting and control may be provided, such as disclosed in the copending US. patent application filed by Harold E. Johns and John A. MacKay on May 18, 1954, Serial No. 430,- 584, now US. Patent No. 2,844,736, entitled Collimator for High Energy X-Ray Beam.

The high energy ray source in the present disclosure is a plurality of cobalt discs 20. The diameter of these discs is a matter of compromise. It is a question of balancing the disadvantages of a large source with the economic advantages in a large source of low specific activity. A source between one and three centimeters in diameter seems to be a suitable compromise with these two considerations in mind. This is the basis for the use of the phrase other-than-point source hereinafter mentioned.

Although the adjustable collimator is disclosed as forming the rays into a beam of square or rectangular transverse cross section, they may be formed into a beam having any desired shape in transverse cross section with a closed perimeter. The shape obtained would depend upon the shape of the beam defining surfaces, the number of diaphragms, and the arrangement of the diaphragms in the collimator.

The description hereinafter will be directed toward describing in detail the adjustable collimator for forming into a beam high energy rays emanating from the source 20 with this beam taking any desired shape or size, depending upon the characteristics of the collamator.

A mounting is provided for the collimator to connect it to the source and to permit rotation of the collimator about a vertical central axis in Fig. 3 extending longitudinally of the ray beam. Here, source 20 is in a shield 21 consisting of a mass of encasing lead, tungsten alloy or other heavy metal surrounded by a steel case 22. A bearing ring 24 is secured to case 22 by a plurality of circumferentially spaced screws 25. A main collimator bearing ring 26 has an auxiliary ring 27 secured thereto by screws 28 to form the inner half of the cylindrical raceway for ball bearings 29. Naturally, rings 24, 26 and 27 are all generally annular in shape so that collimator main ring 26 may be rotated about its central axis and concentric with respect to the source 20. Collimator main ring 26 is secured to a collimator base sleeve 31 in Figs. 3 and 6 by a plurality of circumferentially spaced screws 33. Collinator base 32, secured in any suitable manner within the bore of the base sleeve 31, such as by bolts (not shown), is formed of an upper base portion 32a, preferably formed of dense material such as tungsten alloy to provide a fixed aperture and to control leakage radiation outside the collimator, secured to a lower base portion 32b by screws 32c and having a central conical bore 32d to permit downward passage of the rays from the source 20.

The collimator includes the collimator base 32 and the structure described hereinafter in detail. It has a plurality of spaced diaphragm sets, here shown as 6 /2 sets but of any satisfactory number, arranged in pile formation in 13 layers along, and at right angles to, the axis of the beam. The extra half set is provided to give the desired dimensions and operating characteristics in the specifically illustrated construction.

Each set is composed of a plurality (here shown as four) of L-shaped, ray absorbing movable diaphragms 35, 36, 37 and 38 in Figs. 3, 5, 7 and 8. Diaphragms 35 and 36 are located in one plane or zone extending transverse to the beam axis while diaphragms 37 and 38 are located in an adjacent plane or zone. In each plane, the L-shaped diaphragms are nested together to form a pair, so that when they are assembled in the manner shown in Fig. 5, they fit together to leave a square opening in the center thereof.

Since each diaphragm is substantially identical, only diaphragm 35 in Fig. 5 will be described in detail. This diaphragm has two legs 35a and 35b joined at a vertex with leg 35a being shorter so as to form the horizontal leg of the L-shape, as viewed in Fig. 5. These legs respectively have inner, beam-defining edges 35c and 35d for forming the rays emanating from the source 20 into a ray beam. Diaphragm 35 at the upper left in Fig. 3 is formed of joined layers consisting of an inner lead plate 35c having stainless steel facing plates 35f on top and bottom surfaces thereof. Also, at the vertex, a vertically extending through sleeve 35g (Figs. 5 and 8) is located, preferably being of brass material.

A modified form of diaphragm is shown in Figs. 3a and 3b at 135, which may be substituted for the dia phragms in the bottom four layers in Fig. 3. It has tungsten alloy inserts 135p, 135g mounted by screws and forming beam defining edges 1350, 135d. Tungsten, be ing dense, sharpens the penumbra of the beam. Facing plates 135 may have bearing portions 135f bent over the outer edge of the inner lead plate to serve as a hearing surface for relative movement with the inside surface of the surrounding housing. Similar bearing portions may be formed by bent extensions of plates 35 in Fig. 3, if so desired.

In each set, the four diaphragms 35 to 38 are arranged so that they are progressively displaced degrees about the axis of the beam; note diaphragms 35, 37, 36 and 38 in Fig. 5. However, this so-called progressive displacement need not be in immediately following or clocltwise order, as illustrated. It should be readily apparent that the number of diaphragms in each set, the shape of the opening 40 defined by the inner edges thereof, and the shape of the diaphragms (other than L-shape) may be a matter of choice; and that diaphragms may be arranged to define an opening with any type closed perimeter capable of forming, by the inner edges thereof, the source rays into a ray beam.

Since there are four diaphragms in each set, there are four diaphragm groups with each group having correspondingly positioned diaphragms, such as one group with all the diaphragms 35, a second group with all of the diaphragms 36, etc.

The collimator is provided with interconnected operating mechanisms for moving the diaphragms between the positions shown in Figs. 3 and 8. In the illustrated form, there are four operating mechanisms, interconnected by base 32, with each mechanism operatively connected with correspondingly positioned diaphragms in each set forming one of the four diaphragm groups. Each mechanism adjusts all of the correspondingly positioned diaphragms in its group simultaneously, and adjustment of all four op erating mechanisms will move or adjust all of the diaphragms.

Collimator base 32 has a housing supported thereby and hanging therefrom for enclosing and supporting the diaphragms 35, 36, 37 and 38. This housing has four sides generally forming a square prism in Fig. 3 and expandable into generally a square pyramid in Fig. 8 while maintaining an unbroken enclosure on its periphery for the diaphragms. The diaphragms are constrained to move with the walls of the housing so that the shape of the housing will determine the shape of the beam opening 40. See Figs. 3, 8, 13 and 14.

In the present disclosure, the housing includes in Fig. 5 a plurality of housing side wall members 41, 42, 43

ndMapivotally connectedra't 41a, 42a, q-.and\44a. in,

Figs; 1; 3 and ;5 to, base ;32: to, permit relative pivotal movement. '[;]1e ;hinge center ,lines of these pivots in the present construction define asquare, but may within the scope, of ,this inventiondefine any other rectangle, Whose, sides are paralleljo the sides of the ray beam forming'opening 40 of the diaphragms with the square lying in a plane perpendicular to the beam axis, centered onthetbeam axis, and located as near the source 20 as practicable so that the inner edges of the diaphragms will linev up well withthe edges ofsource 20. Since each side wall member has basically the same construction, onlyjside wal1 =member 43 wil1'be described in detail. Side wall member '43 has an arm- 43b in Fig. 3 having pivot pin 43a at:its upper end and secured at its lower end to a side wallformed by an outer plate 43c and an. inner plate 43d secured together and maintained in spaced relationship by a plurality of spacers 432 and screws :43f.

A plurality o fcorner members (here shown as four in number) 51, 52., 53 and;54' operatively connect adjacent side wall members to complete the formation of the housing in Fig. around the diaphragm sets. Each corner member'isan angle member with theplanar walls thereof. operatively connected tornovere'spectively in the planes of the. adjacent"side wall members. Since each corner member is identical, only the corner member willbedescribecl in detail. It includes two angularly. disposed plates 51a and'5l b;conn ected together by. a corner forming connectingportion 51c. nection between'cornerimember 51 and the adjacent side wall members 41 aim-1,142 is provided by having plate 51a telescoped intgjthefspace between platesA-l'c and 41d (1 having plate '51b 'telescoped into the space between p ates 42 c and 42 1 The contacting side wallsrof these plates are maehined. fiat so that the cornermembers and side wall jme mbers may move telescopically relative to each other between theFdg. 3 and 8 positions in the manner ,showninfFig. 11 by the. dotted andfull line positions. i

Although four side, wall members and four corner members are illustrated, it should be readily understood,

that any desired number may be assembled together to form a housing depending upon the mode of operation.

of the collimator desired and the shape of the ray beam forming opening 40.

Means are providedfor operatively connecting a group. of correspondingly positioned diaphragms to the vertex of each corner member so that the diaphragms are constrained to follow the movement of the housing during expansion and contraction thereof. This is shown in Fig. 5 by having all diaphragms 35 connected to corner member 51 diaphragms 38 to corner member 52, diaphragms 36 to corner member 53, and diaphragms 37 to corner member 54. At each corner, a connecting construction is provided including control bars 61, 62, 63 and 64. Since each [is identical, only control bar' 61 'in Fig. 8 will be described. Control bar 61 includes tie bar 'or cylindrical rod'61a having stop pin 61b adjacent at' least its lower end and a plurality of spherical beads 61c and spacers 61d alternately arranged 'in telescopic relation over tie bar 61a with pin 61b preventing telescopic disassembly. Each of the beads 610, preferably formed of brass or other bearing material, has a generally spherical peripheral surface to form the inner member of a universal joint connection. Every other one of these beads 610 is located in one of the diaphragm sleeves 35g,

while the remainder are locatedin spacer and spring The operative conp r m 35 q io le l i ov me 0 the ne memw,

ber 51.3 Hence,;the outer edges of diaphragm legs 35a andz 35b in 5 are pulled respectively against the innersurfaces of side wall member plates 42d and 41d so that'theorientation and location of ray defining edges 35d and 350 of opening 40in each diaphragm 35: is determined byv the side walls41 and 42.

As analternate construction, control bar 61 may be of one piece construction with a periphery resembling thatknob 71tomove sidewall members 42 and 44in and out. Each drive unit gisjsubstantially identical so only one will be described,namely, the onecontrolled by knob 71., Knob 71 drives a shaft 71a in Fig- 3 having a pinion 72 thereon in Fig. 10 rotatably carried in side,

wall member 41. Pinion 72 meshes with and drives,

gear 73 which in turn drives gear 74, carrying reSPQctivelypinions "73a and 74a,' all'rotatably mounted in side wall member 41'. In Fig. '11, the corner'member plates 51a and 54a have sector gears 75and 76 respec-i tively secured thereto and adapted to be driven by pinions 7% and 73a respectively. Back-up rollers 77 and 78 keep the racks engaged against their respective pinions with these rollers rotatably carried by s'ide wall member 41 In the opposite side wall member 43 in Fig. 3 are located similar gears, pinions, sector gears andback-up rollers with the drive between them being provided through gears73', 79,30 and81 in Fig. '11; gear 81, universal joint 82, cross shaft 83, universaljoint 84 and gear 85 in Fig. 6; and gears 85, 86 and 87in Fig.3.

A similar gearing and drive construction is provided between control knob 70 'and side wall members '41 Hence, one pair of opposite side Wall members, such as 42 and 44, may be swung in or out by knob 71 independently'of the'other sidewall members 41 and '43 to contract orrexpand the ray bea'm forming opening 40 in'only one dimension,such as dimension A inFig; 5L"

The other dim'ension' B is controlled by knob 70; Rota tioh of gears 73 and 74 in Fig; 1 1 will drive corner member plates 51a and '54b'either into or out of'their' respective sidewall'rnember 41. By properly correlating and phasing movements of control knobs 70 and 71,- the housing may be changed in shape from a square prism in Fig. 3 to either'a square or rectangular'pyramid so as to obtain all the different beam'shapes shown in.

Figs. 13 and 14; It should be noted that after a pair of these opposite side walls are properly assembled equidistant from the longitudinal central axis of the beam, the teeth of gears 73, 73a, 74, 74a, 75 and 76 will maintain this equidistant relationship.

The weight of all of these diaphragms 35, 36, 37 and 38 is slidably supported by an expandable frame when-the ray beam is directed downwardly from the source 20 in the manner shown in the drawings. The frame is probably best shown in Figs. 3, 5, 7 and -8. Four bottom frame corners 91, 92, 93 and 94 are provided with four pairs of bottom frame guide rods 95 and 96 telescopical-. ly connected in aligned holes in adjacent corners to-permit the expansion thereof. Between each pair of adjacent corners, a hinge construction is provided. These four hinges have respectively upper leaves 101, 102, 103 and 104 pivotally connected by hinge pins, 105.. to lower leaves.97, 98, 99 and 100.v The upper leaves serve as the spacer between'the inner and outer plates of the respective side wall members 41, 42 43 and 44, while the lower. leaves are bottom frame supports with .each rigidlyrse-i cured to one pair of guide rods 95 and 96. Therefore as the side wall members and corner members move outwardly from the Fig. 3 to the Fig. 8 position, the bottom frame corners 91 to 94 move from the Fig. 4 position in contact with the bottom frame supports 97 to 100 outwardly to the Fig. 7 position by telescoping over their associated guide rods 95 and 96. The expandable frame is rigidly carried by the side wall members and is centrally located with respect thereto by means of bottom frame supports 97-100 and their respective guide rods 95 and 96. The bottom frame corners 91-94 provide support for the lower ends of the control bars 61-64 and for the diaphragms 35-38.

A bottom cover for the collimator is provided by four cover plates 111, 112, 113 and 114 of identical construction, as shown in Figs. 1 and 2. For example, plate 111 has a bottom wall 111a and a turned-up side flange 111b, as shown in Fig. 1. These plates 111, 112, 113 and 114 are secured respectively by screws to bottom frame supports 97, 98, 99 and 100 in Fig. 7 so that the space between them always corresponds with the proper opening 40 for the ray beam because these cover plates will move in and out with the expandable frame.

It has been found that a suitable design is obtained with the present construction with the following dimensions. The treatment distance from source 20 to the skin is about 40 centimeters while the lower end of the collimator, designated by cover plates 111114, is approximately 25 centimeters from the source 20. The range of field sizes formed by opening 40 is from 4 x 4 cm. square to 15 x 15 cm. square. Also, any rectangle having either dimension between 4 and 15 cm. is obtainable. Of course, collimators of this design for other field sizes and treatment distances could be easily produced. Any field size, (square, rectangular, or any other suitable shape) may be obtained. The stack of diaphragms 35-38 is formed in thirteen layers with each being one-half inch thick and each diaphragm having overall dimensions of 4% by 2 inches. The stack is 6% inches high. When the collimator diaphragms are in the Fig. 3 and Fig. 5 position, prismatic beam C in Fig. 13 is produced. When they are expanded into the Fig. 7 and 8 position, a beam of square pyramid form D in Fig. 13 is produced with the slope of the pyramid sides equal to the slope of the side wall members 41-44 of the housing. In this pyramid form, the sides and edges of the pyramid (the edges being shown by lines D1 and D2 in Fig. 8) run through the lateral edges of the source 20 in the manner shown in Fig. 8. This is especially true when an other-than-point source 20 is used. It should be noted that the sides of the prism in Fig. 3 also extend through the lateral edges of the source in a similar manner. This is also true of the intermediate adjusted positions of the collimator.

This construction provides good shielding from stray rays emanating from source 20 and also provides a collimator of compact overall length along the axis of the beam. It should be noted that at least some portions of the diaphragms in each set overlap in every adjusted position, including the maximum spread apart position in Fig. 7. These diaphragms not only overlap along the axial length of the beam but also are in contact with the axially adjacent diaphragms to provide a dense relationship to reduce leakage. The inner edges of the diaphragms form opening 40 with a closed perimeter for forming the rays emanating from the source into a ray beam. The overall height, or length along the axis of the beam, of the stack of diaphragms 35-38 remains constant during adjustment between the Fig. 3 and 8 positions because the diaphragms slide one upon the other and the expandable frame supporting them at the bottom is pivotally connected by hinge pins 105 to the side wall members.

The diaphragm sets are slidably mounted and supported by the adjustable frame. Each set is slidably supported by its adjacent sets with the sets arranged in layers along the length of the beam. Each diaphragm has stainless steel facing plates, such as plates 35 on top and bottom so that sliding of the layers takes place at the junction of the steel surfaces with minimum friction and minimum wear while the lead plate center section, such as 35e, provides maximum ray absorption. Frame corners 91-94 have suflicient contact with the terminal edges of the diaphragms to support their weight even in the expanded position of Fig. 8.

When the diaphragms are in the fully expanded position of Fig. 7 or Fig. 8, it is desirable to provide spacers located axially between the diaphragms along the length of the beam to support correspondingly positioned diaphragms in different layers. As the diaphragms move outwardly, voids are created in other places than in the central opening 40; note Fig. 7. Two difierent type spacers are provided to give proper support.

First, sleeves 66 around the control bars 61, 62, 63 and 64 serve not only as spring holder sleeves but also as spacer sleeves since the axial dimension of each is equal to the thickness of the transversely aligned diaphragm adjacent thereto. These spacer sleeves 66 are provided in two opposite corners of each layer and in all four corners in each diaphragm set. Each spacer remains in the same relative position to its associated corner of the housing for the different collimator adjustment sizes between the Fig. 3 and Fig. 8 positions. They thus maintain the proper spacing between the diaphragm in the expanded position of Fig. 8 that is provided by the diaphragms themselves in the fully closed position shown in Figs. 3 and 5. Each L-shaped diaphragm has a notch, such as notch 35 in diaphragm 35, cut out of the outer surface of its longer leg to provide clearance for the associated spacer when the collimator is fully closed.

Second, the short leg of each L-shaped diaphragm helps support and maintain the spacing between the long legs of the adjacent diaphragms. Note how short leg 35a in Fig. 7 helps support long 38b of diaphragm 38 in the fully expanded position of Fig. 7. Also, the inner edge of this short leg forms a portion of the wall of the opening 40 in all positions of adjustment and is always less than or equal to the dimension of the opening 40 parallel thereto. Compare dimension B in Fig. 5 with the horizontal dimension of the largest square opening 40 in Fig. 7.

The edges of the beam are sharply defined in all positions of adjustment. This is true because all portions of the inner edges of each L-shaped diaphragm forming the ray beam lie in a plane perpendicular to the axis of the beam in every position of adjustment. Hence, the edges of the beam will be sharply defined on a fiat target arranged perpendicular to the beam axis. If some of the portions of a beam defining straight edge were in different planes, the beam edge formed thereby would be a fuzzy instead of sharp.

L-shaped diaphragms normally do not lend themselves to form both rectangular and square beams because of adjustment problems. However, in the present construction, one dimension of rectangular beam opening 40 may be changed while another dimension remains constant. Also, the illustrated construction permits adjusting each diaphragm in two ditferent perpendicular directions both lying in .a common plane transverse to the beam axis.

Two different types of corner member constructions are illustrated in Figs. 9 and 9a. The basic difference between the two is in the connecting portion 51c or 151a. Connecting portion 510 forms a hinge along the vertex of the corner or along the edge of the pyramid formed by the housing. Hinge plate 51a has a generally cylindrical socket end 51:11 wrapped around a cylindrical pivot pin end 51111 formed on hinge plate 51b. Hence, this construction permits relative movement of the walls 51a and 51b not only pivotally about the longitudinal hinge axis of end 51b1 but also along the longitudinal hinge axis, if such last mentioned movement is required during the change in shape of the housing. An inwardly aoaaeso directed lug 51:12 :istormed onthe. periphery ofiithe socket lporti'omextending lalon'gthe. length iof .-.the, .hingelini responding respectively to-plates 51a and' 51b in Fi gJ9a The slot 151d has made the folding operation easier and more accurately performed. The slot, having also had its-side wallsfolded inwardly, forms a dovetail slot or groove running along the length of and inside the vertex of the corner member. A slide memb er, taking the form of the head of a rivet 152 in the presentdisclo'sure, is slidably retained in the groove lSld fortravelalong the length of the grooveif necessary. The opposite ends of each spring 67 are adapted to be detachablysecured to one of the rivets 152 so that the spring 67 Wl l1 pull its associated diaphragm into the vertex of the corner inember. This corner member 151is of rigidangularformw tion so that its construction is much simp'ler thanthe corner member shown in Fig. 9. 'With the Fig. 9a construction, the centers of curvature of the sector gears 75 and 76 in Fig. 11, and those in the other three housing wall members, preferably coincide with .thehing'e axes of pivot pins 41a44a so that relative movement between the hinge plates 151a and 1 51b is not necessary during adjustment of the housing between theFig. 3 and Fig. 8 positions.

However, the hinge construction in ,Fig. 9 does not necessarily needthis coincidence of the pier axes. and the centers of curvature of the sector gear si since relatiye movement is possible between the hinge plates in two different directions. i i i i Alternate constructions within the scope of the present invention readily suggest themselves. First, in Fig. 5, inner plate 51a is carried by cQrner member 5 1 ;while straddling plates 41c and 41d are carried byv side Wall member 41. However, cornermember 51 may be formed. with the straddling plates while side wall. member 41 has the singleintermediate plate, ifso desired," Second, in Fig. 5, correspondingly positioned diaphragms 3 are connected to corner member 51, 38 to 52, 36;;to 53 and 37 to 54. However, correspondingly positioneddiaphragms may be connected with one'of .their associated side walls instead of a corner member. This is especially true if the diaphragms have a straight single beam defining edge instead of being L -shaped.

Indicators are provided for registeringthe size of the opening 40-independently of the gear type driving or operating mechanisms shown in Fig. 11. Here, two identical indicator constructions are provided, one for the housing side wall members controlled by knob 71 and the other for those controlledby knob 70. Since these indicator constructions are identical, only, one is shown in detail and will be described in detail. Adjacentknob 71 in Fig. is the.indicator,120. for. registering movement of side wall members 41 and 43 by. control knob .70. Indicator 120 has an indicia bearing disk.121 ,.in Figs. 3 and 10 with a series of numbers thereonand isadapted to rotate about a central shaft carried by side Wall: member 41, which is carried with the ray beamdefining inner.

edges 35d of correspondingly positioneddiaphnagms 35; Therindiciaisadapted to alignwith a scale: on, the edge of anfopening 1 22 inside wall member 41,upon rotation of.

the disk'121. A cable 123 in Fig. 3 is wrappedaround a drum. 121a coaxiallyv carriedby the disk 121 inFig. 3 ,v

extendsv downwardly ab ont anidler pulley 124i rotatably mounted on a pivot pm 105 in Figs. 7, extends across the center of the ray beam opening 40, is anchored eliminated from the cable. carried by. the opposite side wall'rriember 43, its position will be a function of the inner raybeam, defining edge of diaphragm 36. Therefore, the readingon indicator 121 in window 122 will beat functionof the dimension B in Fig. 5 of ray beam opening 40." In similar manner, the

dimension A'lin Fig. 5 willbe shown by its indicator operatively connected to the cable 123 in a similar man-v ner in Fig. 7. These indicators will register the size of the opening 40. independently of the gear drives in Fig.'

11 so as to eliminate. any back lash error that may occur during movement of the'housing between the different adjusted positions. 7

These crossed cables in Fig. 7 serve another function. The cables 123 and 123- always cross'the center of the path of the beam through the opening 40- at the end of the collimator most remote from the source 20 (at the bottom in Fig. 3) because each cable" is positioned centrally with respect to the opposite side wall members 41 and 43 or 42-and 44 by its associated-pulley 124 and nut 125. In Fig. 3, a light source is provided in the base 32 adjacent the ray source 20 for providing with the helpof mirror 131, extending across base opening 32d, a downwardly extending light beam through the opening 40 coincidingwith the high energy ray beam. If the light source 130 throws downwardly a light beam during use of'the high energy ray beam, the shadow cast upon the target by the crossed cables 123 and 123" will indicate the center of the ray beam to aid in its usage. The cross idifiired will be sharply defined since the cables are fairly near the target and remote from' the light source 130.

Variouschanges in details and arrangement of parts can be made by one skilled in the art without departing from either the spirit of this invention or the scope of the appended claims.

What is claimedis:

1'. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing mow/able diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms with each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly and aplurality of housing side wall me'rnbers pivotally connected to said'base', and including means operatively connecting respectively one side wall member to each group of correspondingly positioned diaphragms.

2. A collimatdr 'for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing' movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms with each mechanism operatively connected with correspondingly positioneddiaphragms in each set for adjusting all or said correspondingly positioned diaphragms simultaneously; said mechanisms including an 'even number of housing sidewall members, including means 'operatively connecting one side Wall member toeach group of correspondingly positioned diaphragms, and including means for swinging opposite side wall members in orout independently of the other side wallmembers to contractor expand saidopening in only one dimension.

3-. A- collimator for high energy rays emanating from a m comprising: .pl rality fi p d di p a m;

ing movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms with each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly positioned diaphragms simultaneously; said mechanisms including a plurality of housing side wall members operatively connected together for relative pivotal movement, and including resilient means operatively connecting respectively one side wall member to each group of correspondingly positioned diaphragms to make them follow their associated side wall member.

4. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms with each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly positioned diaphragms simultaneously; said operating mechanisms including a plurality of side wall members, including a plurality of corner members each operatively connecting adjacent side wall members to form a housing therewith around said sets, and including means operatively connecting at least one corner member to a group of correspondingly positioned diaphragms.

5. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms with each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly positioned diaphragms simultaneously; said operating mechanisms including a plurality of side wall members, including a plurality of corner members each operatively connecting adjacent side wall members to form a housing therewith around said sets, and including drive means operatively connecting each side wall member to at least one of its adjacent corner members for causing relative movement therebetween.

6. The combination of claim wherein said drive means includes meshing pinion and sector gears connected respectively to adjacent members.

7. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms With each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly positioned diaphragms simultaneously; said operating mechanisms including a plurality of side wall members, including a plurality of corner members each operatively connecting adjacent side wall members to form a housing therewith around said sets, including a control bar extending through aligned holes in a group of correspondingly positioned diaphragms, and including means for resiliently pulling said bar toward one of said corner members and said last mentioned diaphragms against side wall members adjacent said last mentioned corner member.

8. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of a plurality of ray absorbing movable diaphragms defining an opening with a closed perimeter for forming said rays into a beam, and operating mechanisms With each mechanism operatively connected with correspondingly positioned diaphragms in each set for adjusting all of said correspondingly positioned diaphragms simultaneously; said operating mechanisms including a plurality of sidewall members,

including a plurality of corner members each operatively connecting adjacent side wall members to form a housing therewith around said sets, and at least one of said corner members is an angle member with the planar walls thereof operatively connected to move respectively in the planes of the adjacent side wall members.

9. The combination of claim 8, wherein said last mentioned corner member is of rigid angular formation.

10. The combination of claim 8, wherein said side wall members are four in number with each pivotally mounted along an axis and said axes define a rectangle around said beam in a plane normal to said beam, all of said corner members are of rigid angular formation and each is pivotally mounted to swing about either of two of said axes.

11. The combination of claim 8, wherein said last mentioned corner member is hinged along its vertex.

12. The combination of claim 11, wherein said hinge is constructed to permit relative movement of said planar walls along the hinge axis.

13. The combination of claim 8, wherein means operatively connects correspondingly positioned diaphragms in each set to the vertex of said last mentioned corner member.

14. The combination of claim 13, wherein said last mentioned corner member is of rigid angular formation and has a groove running along the length of and inside the vertex thereof, and said connecting means includes a slide member slidably retained by said groove for travel along said groove and a flexible connector operatively connecting said slide member and at least some of said correspondingly positioned diaphragms.

15. The combination of claim 8, wherein said operative connection between the wall of one corner member and one side wall member includes one member having a plate telescoped between two plates spaced apart on the other member.

16. A collimator for high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets, each set being composed of four ray absorbing movable diaphragms defining a rectangular opening for forming said rays into a ray beam, operating mechanisms with each mechanism operatively connected with correspondingly positioned diaphragms in each set forming one of four diaphragm groups for adjusting all of said correspondingly positioned diaphragms in one group simultaneously, two indicators connected respectively one to each of adjacent correspondingly positioned diaphragm groups, two cables with one for each indicator, each cable having one end carried by a diaphragm in the group positioned opposite the indicator and the other end operatively connected to said indicator for actuation thereof responsive to the size of said opening, said indicators and cables being arranged so that said cables cross the center of said ray beam at the end of said sets remote from said ray source, a light source adjacent said source providing a light beam through said opening corresponding with the high energy ray beam, and means for adjusting at least some of said diaphragms to change the size of said opening while automatically maintaining in each adjustment said cables crossing the center of the path of said beam and opening, whereby the shadow cast by said cables indicates the center of said beams.

17, A collimator for high energy rays emanating from a source, comprising a plurality of L-shaped ray absorbing movable diaphragms defining a closed rectangular opening for forming said rays into a beam, andmeans operatively connected with said diaphragms on opposite sides of said rectangular opening for relatively moving some of them in rectilinear motion parallel to one side of said rectangular opening, and for moving others of said diaphragms in rectilinear motion in the direction at right angles to said first motion, whereby to change each dimension of said rectangular opening independently of its other dimension.

18. A collimator for forming into a beam high energy rays emanating from a source, comprising a plurality of spaced diaphragm sets of two pairs each, said pairs in adjacent layers, said diaphragms all having L-shaped beam defining edges with the vertexes of the edges of .one pair lying at two opposite corners of a rectangle and with the vertexes of the edges of the adjacent pair lying at the other two opposite corners of said rectangle, said diaphragms having legs in adjacent pairs lying along the same side of said rectangle and extending in opposite directions along said side and overlapping each other, and means operatively connected with said diaphragms on opposite sides of said rectangular opening for relatively moving them in rectilinear motion in the direction of one side of said rectangular opening and for moving others of said diaphragms in rectilinear motion in the direction at right angles to said first motion, whereby to change each dimension of said rectangular opening independently of its other dimension.

19. A collimator as in claim 18 wherein the dia phragms in all of said layers are flat and slidingly engage the diaphragms in adjacent layers to provide a dense beam-shielding relationship.

20. A collimator as defined in claim 17 including two indicators, cables carried respectively one by one of said diaphragms which is movable in the direction of one side 14 of said rectangle and the other by one of said diaphragms which is movable at right angles to said first motion, and each of said cables operatively connected to one of said indicators to actuate the latter responsive to the dimension of said opening in the direction of the associated rectilinear motion, said cables intersecting at the center of said rays passing through said collimator at the end thereof remote from said source, and a light source adjacent said ray source providing a light beam through said opening coinciding with the axial center of said rays, whereby the shadow cast by said cables indicates the center of said collimated rays.

References Cited in the file of this patent UNITED STATES PATENTS 1,909,118 Raab May 16, 1933 1,976,179 Mannl Oct. 9, 1934 2,181,620 Haupt Nov. 28, 1939 2,187,246 Nerwin Jan. 16, 1940 2,542,196 Haupt Feb. 20, 1951 2,544,779 Daly Mar. 13, 1951 2,614,224 Wright Oct. 14, 1952 2,675,486 Green et a1. Apr. 13, 1954 2,844,736 Johns et al. July 22, 1958 2,881,329 Peyser Apr. 7, 1959

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Classifications
U.S. Classification378/152, 378/206, 976/DIG.430
International ClassificationG21K1/04, G21K1/02, A61N5/10
Cooperative ClassificationA61N5/10, G21K1/04
European ClassificationG21K1/04, A61N5/10