US3091696A - Collimator - Google Patents

Description

L. F. PEYSER May 28, 1963 COLLIMATOR 4 Sheets-Sheet 2 Filed May 17. 1960 INVENTOR LEONARD F. PEYSER 1%.- 4 1:5

ATT o RNEY May 28, 1963 1.. F. PEYSER 3,091,696

COLLIMATOR Filed May 17, 1960 4 Sheets-Sheet 3 INVENTOR LEONARD "F. PEYSER BY I gF ORNEY Stats This invention relates to improvements in collimators for use with X-ray machines.

It is an object of the invention to provide a collimator capable of sharp definition of rectangular fields, and which is compact so as to permit attachment to various X-ray machines while permitting angular movement about a hori- Zontal axis Without interference between collimator and the rails of the machine.

A second object is to provide a collimator having means for adjusting a rectangular field by means of a single adjustment while maintaining a fixed proportion between the long and short sides of the field rectangle.

Another object is to provide an adjustment of the character just indicated while permitting uncoupling of collimating elements to permit the selection of fields having different ratios between sides, when desired.

Another object is to provide an improved centering light and margin light illuminating arrangement for the collimator.

A collimator embodying the invention in a preferred form will now be described with reference to the accompanying drawing, and the features forming the invention will then be pointed out in the appended claims.

In the drawing:

FIG. 1 is an isometric showing the collimator device of the invention in position on an X-ray machine;

FIG. 2 is a side elevation of the collimator of FIG. 1;

FIG. 2A is a fragmentary view, similar to FIG. 2, but showing the parts in a different position;

FIG. 3 is an enlarged bottom elevation of the collimator of FIG. 1;

FIG. 4 is a section on the line 44 of FIG. 3;

FIG. 5 is a fragmentary section, similar to FIG. 4, showing the movement of the parts;

FIG. 6 is a schematic diagram showing the aperture adjustment;

FIG. 7 is a schematic fragmentary view similar to FIGS. 4-6 but showing a modified collimator bar linkage or mounting; and

FIG. 8 is a view similar to FIG. 7, but showing the parts in another position of adjustment.

The collimator comprises a casing 10, easily attached to an X-ray unit 11, by thumb screws 12, and fitting between the usual rails 13 on which the unit 11 is carried.

The collimator casing includes an upper housing section 14 having a top cover 15 which carries a centering light mirror 16 (constructed as shown in prior Peyser application, Serial No. 708,027, filed January 9, 1958, for X-ray Gone). The body 17 of this upper housing section carries the thumb screws 12, previously referred to, and has a central aperture 18 accommodating a rotatable ring 19 which is held up in place by plate 20 secured to the body 17. A ball spring detent 21 serves to hold the ring 19 releasably in one or more predetermined angular positions by engaging in a notch or notches 22 in the ring 19, as shown. The lower housing section 23 has a central upper opening with inward facing lip 24 which is secured to the ring 17 by a central tubular r-ivet member 25, so that the lower casing section 23 is securely held to the upper housing but may be turned about the axis of the collimator.

The upper part 23' of the lower casing section 23 is reduced in diameter, as shown, while the lower part 23 is of larger diameter, for accommodating the operating tent ice

mechanism about to be described. This mechanism comprises a pair of aperture plate arms 30 swingable in one plane and a second pair of arms 31 swingable in a plane at right angles thereto, the four arms serving to define a rectangular beam, by means of upper aperture plates 32 and lower aperture plates 33 and bars 34, carried by the arms. Two points of support for each arm assembly 30 or 31 are provided, the first being a pivot bracket 35 secured to a masking plate 36 fixed in the upper part of the lower casing element 23, as by means of the posts 37 and the second being a pin 38 carried by a link 60 pivotally mounted in a bell crank 61 by pin 62, which bell crank is pivotally mounted at 63 on a block 64 secured to the housing wall (FIG. 4). Pin 38 passes through a rubber grommet 41 in a hole in the aperture plate 33, allowing limited movement of the pin relative to the plate.

The mounting of arms 30 (and 31) comprises a linkage assuring the proper positioning of the collimating elements as the diameter of the opening is varied. The linkage comprises for each arm 30 a main support arm or link 45 pivotally supported by the bracket 35 and pivotally attached at 46 to a block 47 secured to the arm 30, so that the axis of the pivot 46 can move in the arc 48, indicated in FIG. 4, and is confined to movement in this arc. The angle between link 45 and arm 30 and the various positions of the link is determined by linkage elements comprising a cam arm '50 mounted to the link 45 on a pivot 51. One end of the cam arm 50 carries a pin or roller 52 which rides in a slot 53 parallel to the arm 30 and fixed to the pivot block 47 previously referred to.

As will be apparent, determination of the angular position of arm 50 relative to link 45 also determines the angle between link 45 and arm 30. The upper end of the cam arm or link 50 is formed as a hook 54, the inner surface of which rides against a pin mounted on the support bracket 35. As will be apparent, the engagement of the cam surface on the inside of the hook 54 and pin 55 will, in any angular position of the link 45, determine the angle of link 50 relative thereto and, hence, the angle of the aperture plate arm 30. A spring 56 attached to the arm 30 at 57 and to the arm 45 at 58 passes around a roller 59 carried by the arm 45 and serves to pull the arm '30 towards the link 45, thus also by reason of the engagement of pin 52 in slot 53, pressing the hook 54 against pin 55. As will now be apparent, movement of pin 38 will move the lower aperture plate 33 in or out to the required position for regulating the opening and at the same time will cause arm 45 to swing about the pivot at its upper end, while arm 30 also swings about its pivot 46, this compound movement positioning the aperture plates and bars in proper collimating relation. The effect is, as shown in FIG. 6, that the arms 30 swing about a common pivot center which may be at the emission center of the X-ray machine and which point is located above the collimator housing.

Pin 38, previously referred to, is carried by a short connecting arm or link 60, the other end of which is pivotally connected to a bell crank 61 by pin 62. Bell crank 61is, in turn, pivotally mounted at 63 on a block 64 secured to the housing wall and its other arm carries a pin 65 which is received in cam slots 66 formed in rotatable drive ring 67, so that the turning of the ring 67 causes the bell crank 61 to swing about its pivot 63 and thus through link and pin 38 move the arm 30 as required. The arrangement for moving the arms 31 is similar, except that the pins are somewhat longer and pass through cut outs 68 in the ring 67 so as to be received in cam slots 66' formed in an upper rotatable ring 67'. The cam slots are formed so as to give about inch of movement to pin 65 or pin 65' in 60 or less rotation of the ring, and the bell crank arms are formed so as to obtain up to about an inch and A3 of movement of the lower aperture plate 33. Each ring 67, 67' is formed with gear teeth on a part of its circumference and a pinion 69 or 69' turned by means of a hand wheel '78 or 74? serves for adjusting the rotary position of the two gear wheels and, hence, the pair of collimator arms 38, as desired.

A scale 71 carries suitable indicia for indicating the film size or sizes of exposed field at various distances, these distances being, in the case illustrated, 36, 40, 48 and 72 inches, respectively, and a horizontal line being provided on the scale for each of these distances. Associated with each line are numerals above the line (which may be in red for further distinguishing them) and numerals below the line (which may be in black), the upper numerals being read against a transparent index strip 72 which is aflixed to the ring 67, and a transparent pointer strip 72 afiixed to the ring 67'. These two rings are shown as having, respectively, horizontal and vertical arrows and these arrows may be in black and red, respectvely, as also the adjacent index lines 73, 73' on the transparent strips. The numerals above and below the respective horizontal lines on the scale 71 indicate the dimensions of the size of the exposure rectangle or film size obtained when the lines 73, 73 are registered with the marks associated with the numerals. For example, setting the transparent index strip lines over the extreme left hand mark on the 36 inch line of the scale will give a proper size field for exposing a -5 x 7 film. While setting the index lines over the mark toward the other end of the horizontal line will give proper collimation for a 14 x 17 film.

It will be observed that setting the lines of the transparent pointers on a common mark will collimate for the film sizes indicated on the scales, and means is provided for coupling the two rings 67, 67 and, hence, their index pointers together so they may be moved as a unit by using only one of the knobs 70, 70. This means comprises a spring pressed plunger or catch 75 vertically movable in a housing 76 attached to the upper ring 67' and accommodated in a slot in the collimator casing. Attached to the catch pin 75 is a head 77 having a rib 78 adapted to seat in a groove 79 in the pin housing 76, as shown in FIG. 2-A of the drawing, or when turned at right angles to sit above it, as shown in FIG. 2. The head 77 and pin 75 are preferably urged downwardly by a spring (not shown) within the casing 76. With the catch in the position of FIG. 2-A, the pin 75 enter-s an aperture in the lower ring 67, thus locking the rings 67 and 67' together for rotation as a unit, the aperture being positioned so that this movement collimates to a rectangle of proportions above indicated. If the catch is set in the upper position of FIG. 2, the two rings may be turned independently for selecting rectangles of any other desired proportions as may from time to time be necessary. For the bulk of actual work, film sizes in the indicated dimensions will he used, so that the device is normally employed in the locked arrangement of FIG. 2-A, requiring only the setting of a single knob and reading of a single scale, thus speeding up the procedure and minimizing errors.

The mounting of the lower casing half 23 for rotation about the collimator axis with respect to the upper casing structure 17, etc. permits the turning of the film exposed as desired. In particular, the grooves 22 cooperating with ball dete-nt 21, previously referred to, will normally be located in two positions 90 apart so as to permit easy and automatic setting in either of two positions at right angles to each other. It will be observed that the upper aperture plates 32. which are enclosed within the upper part of the housing are of consider-ably greater diameter in their outward position than the opening in rivet 25 so that the housing has a neck or narrow portion of less than the diameter required to accommodate the upper aperture plates and moreover that the arms 3%, 30" are located at the inward edges of the aperture plates so as to require the least possible space. In consequence, the casing between the upper aperture plates and rings 67, 67 may be made, as shown, of reduced diameter and of less diameter than the upper housing 17. In View of this, considerable clear ance is provided between the housing '23 and the rails of the X-ray machine, thus permitting tilting of the X-ray unit about a horizontal axis for exposures requiring this position. The upper cover 15 which may conveniently he made of aluminum alloy and the housing structure generally provide filtering and shielding against soft radiation, while the upper and lower plates 32, 33, bars 34 and stationary plates 36 provide complete blocking of off focus radiation for protecting the patient outside the radiographi-c area, together with maximum field definition. Each of the aperture defining elements being formed, as indicated, as a laminated structure utilizing lead sheeting for maximum blocking of radiation in conjunction with aluminum alloy and aluminum alloy layer or layers for obtaining the required mechanical strength and durability of the parts.

The arms 3%, 31 are preferably made of copper, as this material is X-ray absorbent and non-reflective. The lower bars 34 serve to block any radiation passing through the cut outs in the aperture plates accommodating the bars and also to clean up any residual scattered radiation which passes the lower aperture plates 33.

The visual optical system of the collimator includes a center light which comprises a light and lens unit mounted in one wall of the housing 23 and projecting a generally horizontal beam to a mirror 81 set midway between a pair of bars 30, 31 and reflecting the beam upwardly to mirror 16, previously referred to, the angle being such that the beam is then reflected vertically downward along the axis A of the collimator. The visual optics include also means outlining the field of exposure and these comprise for each collimator arm 30 a projector unit 85 including a housing fixed to the arm 30 or 31 adjacent the bar 34 and containing a light and lens system for projecting a line of light in substantial parallel-ism to the arm 30 or 31 as the case may be. The angle of the edge defining means E with relation to the arms 30 is selected so as to obtain precise indication of the field at an intermediate exposure distance, such, for example, 48 inches, the panallax area at other exposure distances being negligible.

FIGS. 7 and 8 show a modified form of linkage or mounting which does not require springs for moving the elements in either direction and which may be constructed without pin and slot connections. In this structure, the casing and general opera-ting elements may be the same as in the construction previously described and are identified 'by similar reference numerals so that specific description appears unnecessary.

Collimator bar 31 (the linkage for the bars 30 being similar is not illustrated) is constructed similarly to the bar 3-1 of FIGS. 4 and 5 and carries upper and lower aperture plates 32, 33 as before, the adjustment motion being imparted to this bar by means of pin 38 operated by the stud 65' and adjusting ring element 67', as before. The collimator bar is, however, suspended in a dilferent manner. Secured to or formed with the bar 31 is a bracket having a pivot connection 9 1 to the lower end of link 92, the upper end of which has a pivot connection 93 to an anchor block 94 which is fixedly mounted on stationary element 36, pivot axis 91, accordingly, swings in a fixed are around the axis of pivot 93 and the bar 31 swings accordingly. Formed on the anchor 94 is a gear tooth sector 95 meshing with corresponding gear teeth 96 formed on an arm 97 having a pivotal mounting 98 on the arm 92. The opposite end of arm 97 has a pivot connection 9% to a short link 100, the other end of which has a pivot connection 101 to the bracket 90 previously referred to and which is secured to or forms part of the collimator bar 3-1. When the aperture is adjusted, movement is imparted through end 38 to the collimator bar 31 and, hence,

to the pivot connection 91, swinging the link 92 around the axis of pivot 93. At the same time, due to the meshing of teeth 95 and 96, arm 97 will be rotated with reference to arm 92, thus swinging bar 3-1 with reference to 92 around the pivot point 91. The positioning of the pivot points and the ratio of the gearing 95-96 are selected to give the required position of the aperture plates in any position of adjustment.

Considering FIGS. 7 and 8, it will be apparent that when the arm 92 is swung through any angle (as, for example, from the position of FIG. 7 to that of FIG. 8), the pivot 91 moves from one determinate position to another. At the same time, gear sector 96 rolls around fixed gear sector 95, thus also moving through a determinate angle and causing the element 97 to rotate with reference to arm 92 and, hence, acting through link 100 to swing the collimator bar 31 through a determinate angle with reference to the arm 92, so that position of the collimator bar is determined. That the adjustment is a fixed and predictable one is apparent from the following considerations: With the parts in the position of FIG. 8 and leaving the element 38 in fixed position, if it be attempted to swing the bar 31 about the pivot 91, it will be apparent that a rotation of arm 97 about pivot 98 will be required. Since the meshing teeth 95 are fixed, this rotary movement is prevented so that there is one and only one position of bar 31 with reference to the arm 92 which is permitted. Similarly, if it be attempted to swing the arm 92 about its pivot (pin 38 remaining in fixed position as before) it will be apparent that this motion also is prevented. As will be apparent, this swinging movement would require an angular movement of bar 31 with respect to arm 93 in a retrograde direction and through an angle comparable to the angle of movement of the bar 92. However, the resultant movement at pin 38 is about the remote pivot point 93 in one case and the close pivot point 91 in the other, so that arm 92 cannot be moved from the position of FIG. 8 or FIG. 7 without movement of the pin 38.

What is claimed is:

1. An X-ray collimator comprising a housing, two pairs of collimator bars, a plurality of aperture plates carried by each said bar and spaced therealong, and means mounting the said pairs of bars in the housing for movement in two axial planes at right angles to each other, whereby each said pair of bars adjustably defines the opposite sides of a rectangular radiation beam, the said mounting means for a bar comprising a linkage supporting the said bar for swinging movement about a center located on the collimator axis and above the collimator housing, and in which the said linkage comprises an arm pivotally supported from the housing at one end and pivotally supporting the bar at its other end, and cam means for swinging the bar about its axis of pivotal attachment to the said arm in predetermined angular relationship thereto.

2. An X-ray collimator according to claim 1, in which the said cam means comprises a second arm pivoted intermediate its length to an intermediate point on the first said arm, a pin and slot connection between one end of the second said arm and the bar and a cam connection between the other end of the said arm and the housing.

3. An X-ray collimator according to claim 2, in which the said linkage cam means comprises also spring means acting between the first said arm and the bar and opposing the action of the cam.

4. An X-ray collimator according to claim 3, in which the said spring means comprises a spring attached at one end to the first said arm, a roller carried by the said arm and spaced from the said spring, the said spring passing around the roller and having its other end attached to the said bar, whereby the total length of the spring is a multiple of the distance from the said roller to the point of attachment of the spring to the bar.

5. An X-ray collimator comprising a housing, two pairs of collimator bars, a plurality of aperture plates carried by each said bar and spaced therealong, means mounting the said pairs of bars in the housing for movement in two axial planes at right angles to each other, whereby each said pair of bars adjustably defines the opposite sides of a rectangular radiation beam, the said mounting means for a bar comprising a linkage supporting the said bar for swinging movement about a center located on the collimator axis and above the collimator housing, and means for adjusting the aperture comprising a pair of superposed operating ring plates, cam slots in the said ring plates and pins in the said slots for operating the said bars, the pins in one said ring plate being connected to one opposed pair of bars and those in the other said ring plate to the other said pair, one of the said ring plates having also apertures accommodating the pins in the cam slots of the other said ring plate.

6. An X-ray collimator comprising a housing, two pairs of collimator bars mounted therein for respectively adjustably defining the opposite edges of a rectangular radiation beam, an operating member and aperture indicating scale for one said pair of bars and an operating member and aperture indicating scale for the second said pair of bars, means for operating the said members independently to adjust the aperture and releasable coupling means for locking the two said members together for moving in unison, the two said members having operating ranges through which equal movements of the members produce substantially proportional changes in the two dimensions of the radiation beam, the said proportional changes being in the ratio of 4:5.

7. An X-ray collimator according to claim 6, in which the scales are coincident through the said ranges, With the indicia thereof in the ratio of 4:5 and comprising transparent pointer means connected to the said members and superposed when the two said members are locked toge-ther by the said coupling means.

8. An X-ray collimator comprising a housing, two pairs of collimator bars mounted therein and carrying spaced aperture plates for respectively adjustably defining the opposite edges of a rectangular radiation beam, the collimator bars being positioned at the edges of the said beam and the aperture plates extending outwardly from the bars to cut off radiation outside the edges of the beam and means for pivotally moving the said bars about a center above the housing to adjust the aperture, the said housing comprising upper and lower portions of a width sufficient to accommodate the aperture plates and an intermediate narrower neck portion, whereby said neck portion provides clearance between the rails of an X-ray machine for bodily swinging the collimator.

9. An X-ray collimator according to claim 8, comprising means rotatively supporting the said narrower neck portion from the said upper housing portion for permitting angular movement of the neck portion and lower housing portion about the collimator axis, and in which the collimator bars are mounted in the angularly movable part of the housing for movement therewith.

10. An X-ray collimator comprising a housing, two pairs of collimator bars, a plurality of aperture plates carried by each said bar and spaced therealong, and means mounting the said pairs of bars in the housing for movement in two axial planes at right angles to each other, whereby each said pair of bars adjustably defines the opposite sides of a rectangular radiation beam, the said mounting means for a bar comprising a linkage supporting the said bar for swinging movement about a center located on the collimator axis and above the collimator housing, and in which the said linkage comprises a first arm pivotally supported from the housing at one end and pivotallysupporting the collimator bar at the other, a second arm pivotally carried by the first said arm, a link pivotally connected to the said second arm and to the collimator bar for angularly moving the collimator bar with reference to the first said arm, and means for angularly moving the said second arm with reference to the said first arm in predetermined relation to the angular movement of the said first arm.

11. An X-ray collimator according to claim 10; in which the means for angularly moving the said second arm comprises cooperating gear segments, respectively, concentric about the first arm pivotal axis and the second arm pivotal axis and fixed, respectively, to the housing and to the said second arm.

12. An X-ray collimator linkage comprising a collimator bar having aperture plates for defining an X-ray beam, a first arm, a pivot supporting the said arm for angular movement about the pivot axis, a pivot connecting the collimator bar to the said arm for angular movement with respect thereto, a second arm pivotally carried on the said first arm and a link connecting the second said arm to the collimator bar for fixing the angular position thereof with respect to the said first arm, a fixed gear sector concentric about the pivotal axis of the said first arm and a gear sector meshing therewith and carried by the said second arm concentrically about its pivotal axis.

13. An X-ray collimator link-age comprising a collimat-or bar having aperture plates for defining an X-ray beam, a first arm, a pivot supporting the said arm for angular movement about the pivot axis, a pivot connecting the collimator bar to the said arm for angular movement with respect thereto, a second arm pivotally carried on the said first arm and a link pivotally connected to the second said arm and to the collimator bar for fixing the angular position thereof With respect to the said first arm, a fixed gear sector concentric about the pivotal axis of the said first arm and a gear sector meshing therewith and carried by the said second arm concentrically about its pivotal axis.

References Cited in the file of this patent UNITED STATES PATENTS I-Iaupt Nov. 1, 1955 Barrett July 7, 1959 Green Nov. 8, 1960

Claims (1)

1. AN X-RAY COLLIMATOR COMPRISING A HOUSING, TWO PAIRS OF COLLIMATOR BARS, A PLURALITY OF APERTURE PLATES CARRIED BY EACH SAID BAR AND SPACED THEREALONG, AND MEANS MOUNTING THE SAID PAIRS OF BARS IN THE HOUSING FOR MOVEMENT IN TWO AXIAL PLANES AT RIGHT ANGLES TO EACH OTHER, WHEREBY EACH SAID PAIR OF BARS ADJUSTABLY DEFINES THE OPPOSITE SIDES OF A RECTANGUALR RADIATION BEAM, THE SAID MOUNTING MEANS FOR A BAR COMPRISING A LINKAGE SUPPORTING THE SAID BAR FOR SWINGING MOVEMENT ABOUT A CENTER LOCATED ON THE COLLIMATOR AXIS AND ABOVE THE COLLIMATOR HOUSING, AND IN WHICH THE SAID LINKAGE COMPRISES AN ARM PIVOTALLY SUPPORTED FROM THE HOUSING AT ONE END AD PIVOTALLY SUPPORTING THE BAR AT ITS OTHER END, AND CAM MEANS FOR SWINGING THE BAR ABOUT ITS AXIS PIVOTAL ATTACHMENT TO THE SAID ARM IN PREDETERMINED ANGULAR RELATIONSHIP THERETO.

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