115
`United States Patent
`5,889,834
`[11] Patent Number:
`
`[45] Date of Patent: Mar. 30, 1999
`Vilsmeieret al.
`
`US005889834A
`
`[54] BLADE COLLIMATOR FOR RADIATION
`THERAPY
`
`[75]
`
`Inventors: Stefan Vilsmeier, Poing; Michael
`Bertram, Heimstetten; Joseph Doyle,
`Munich,all of Germany; Ueli Graf,
`Mettmenstetten, Switzerland
`
`Assignee: Brainlab Med. Computersysteme
`GmbH, Heimstettn, Germany
`
`Appl. No.: 722,602
`
`Filed:
`
`Sep. 27, 1996
`
`Foreign Application Priority Data
`p. 28,1995
`[DE]
`Germany ....... ee 195 36 188.1
`
`Tint. C10 ooceccccscccsssesssssssssseesssesesssesssssvesenes G21K 1/02
`US. Ch...
`378/147; 378/150; 378/152
`Field of Search oo...ccc 378/146, 147,
`
`78/148, 151, 152, 160
`
`
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,166,531
`5,297,037
`5,433,048
`5,591,983
`
`11/1992 Huntzinger ......eeee 378/152
`3/1994 Ifuku ........
`. 378/152
`
`7/1995 Strasser
`52/288.1
`A/1997 Yoav secesecssenssesseenseenecenneees 378/152
`
`FOREIGN PATENT DOCUMENTS
`
`0 245 768 BI
`4203 610 C1
`
`11/1987 Turopean Pat. Off. .
`8/1994 Germany.
`
`Primary Examiner—Don Wong
`Attorney, Agent, or Firm—Armstrong, Westerman, Hattori,
`McLeland & Naughton
`
`[57]
`
`ABSTRACT
`
`The accuracy of radiation therapyis enhanced with the blade
`collimator of the claimed invention. Particularly, this colli-
`mator includes a support device for supporting at least two
`sets of radiation attenuating blades in a single plane or layer.
`The blades are reciprocally movable within this support.
`Shaping of the therapy maybe increased by constructing the
`blades to include a varying width increasing from the central
`blade toward the exterior blades.
`
`5,012,506
`
`4/1991 Span et ab. vce ereeereee 378/152
`
`24 Claims, 3 Drawing Sheets
`
`
`
`
`
`73
`
`
`
`ViewRay Exhibit 1028
`Page 1 of 8
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`ViewRay Exhibit 1028
`Page 1 of 8
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`

`

`U.S. Patent
`
`Mar. 30, 1999
`
`Sheet 1 of 3
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`5,889,834
`
`
`
`=
`
`Li,
`
`ViewRay Exhibit 1028
`Page 2 of 8
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`ViewRay Exhibit 1028
`Page 2 of 8
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`

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`U.S. Patent
`
`Mar. 30, 1999
`
`Sheet 2 of 3
`
`5,889,834
`
`iN
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`23
`
`P
`
`l
`
`7
`
`OILA
`
`i
`
`24 [yi
`
`
`|fyt| i
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`CokTT hAAY
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`
`Fig.2
`
`ViewRay Exhibit 1028
`Page 3 of 8
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`Page 3 of 8
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`

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`U.S. Patent
`
`Mar. 30, 1999
`
`Sheet 3 of 3
`
`5,889,834
`
`Fig.3
`
`3I
`
`32
`
`36
`
`33
`
`34
`
`35
`
`ViewRay Exhibit 1028
`Page 4 of 8
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`ViewRay Exhibit 1028
`Page 4 of 8
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`

`

`5,889,834
`
`1
`BLADE COLLIMATOR FOR RADIATION
`THERAPY
`
`The invention relates to a blade collimator for radiation
`therapy of the class described in the introductory clausc of
`claim 1.
`Blade collimators are accessories of linear accelerators
`that are used especially to irradiate tumors. They were
`developed to limit the area of radiation,
`to protect vital
`tissues from radiation, and thus to replace the traditional
`shielding blocks, which must be made to order for each
`tumor and are expensive to manufacture. Although these
`shielding blocks, because they are cast separately for each
`tumor, naturally permit very good adjustment to the shapes
`of tumors, it was desirable to create and employrelatively
`adjustable, reusable devices for
`limiting the area of
`radiation, using blade collimator technology, suitable for a
`range of tumor shapes.
`Basically, blade collimators have two sets of separately
`movable blades facing each other;
`their front faces are
`pushed together in such a way that the blades circumscribe
`an open area between the front faces that coincides fairly
`well with the contour of the tumorto be treated. The blades
`can be moved manually, electrically, or mechanically by
`means of spring mechanisms.
`Twobasic classes of blade collimators are knownto prior
`art. In the first class, relatively wide blades, often made of
`tungsten,are usedto treat larger tumors. The width of blades
`for such collimators ranges from 6 mm to 1 cm, which
`permitsirradiation of large areas of great width up to 60 cm.
`The front faces of the blades have a rectangular shape.
`This causes a problem in the use of collimators with wide
`blades: when the front faces are moved toward the contour
`of the tumor, it proves impossible to achieve a satisfactory
`match with the shape of the tumor. If the front faces of the
`blades are moved up to their first point of contact with the
`contour of the tumor, then the staircase pattern thus formed
`leaves open relatively large areas through which radiation
`can strike and damage vital tissue. This becomes an espe-
`cially serious problem whentreating the brain. If the blades
`are moved up in such a way that no vital tissue is left
`exposed to the radiation, this causes the opposite problem:
`the “stair landings” that are formed by the front faces of the
`blades cover parts of the tumor, which then cannot be
`treated. Moreover, the scattering of radiation reaches a high
`level with such collimators;
`the dose gradicnt becomes
`small. Overall, it may be concludedthat the collimators with
`wide blades described above can indeed be used to irradiate
`large areas, but cannot be adequately adjusted to match the
`shape of the object to be irradiated.
`In order to solve this problem, a second class of blade
`collimators that employ very narrow blades was developed.
`Such blades, which are as narrow as 1 mm, in principle
`permit good adjustmentof the localized radiation area to the
`shape of the tumor. Yet there arc substantial disadvantages
`associated with devices of this type, particularly as regards
`the size of the area that can be irradiated.
`The number of bladesthat can be used is limited. This is
`because each blade mustbe able to be independently shifted
`by mechanical means, for which purpose each blade is
`generally equipped with an activating and shifting mecha-
`nism. These shifting mechanisms—which can be electric
`motors, for example—mustall be mounted on the collimator
`or its support. This necessarily places an upper limit on the
`numberof blades because too many of them would make the
`collimator,
`together with its support and activating
`mechanisms, too large and too heavy.
`
`3o
`
`35
`
`40
`
`5o
`
`55
`
`60
`
`65
`
`2
`A limited numberof blades of lesser width restrict such
`a collimator to the irradiation of very small areas. Therefore,
`despite the relatively good adjustment, such a collimator is
`limited to a rather small area of application (e.g. the irra-
`diation of small tumors).
`Acontour collimatorfor radiation therapyis known from
`European patent number specification 0 245 768, which
`describes an effective adjustment device for the blades.
`Another contour collimator is known from German patent
`specification number 42 03 610; it employs a spring mecha-
`nism and a readjustment device for the blades. These two
`collimators of prior art also operate with blades of uniform
`width; that is, they are also beset by the problems associated
`with narrow or wide blades that are described above.
`The goal of the present invention is to provide a blade
`collimator for radiation therapy that solves the aforemen-
`tioned problems. In particular, a blade collimator will be
`suggested that makes possible both good adjustment to the
`contour of the object to be irradiated and irradiation of
`relatively large areas.
`This goal is attained with a blade collimator designed
`according to the characterization part of claim 1.
`The subsidiary claims describe preferred embodiments
`of the blade collimator according to the invention.
`The main advantage of using blades of various widths
`within a blade field of the collimator is that it becomes
`possible to use narrowbladesat those places where a precise
`adjustmentto the contourto be irradiated is necessary, while
`wider blades can be employed at those places where they
`provide adequate adjustment—for example,
`those tumor
`contours that are relatively straight, against which the wide
`blades can be laid lengthwise with a good fit. By using both
`narrow and wide blades,
`it becomes possible to irradiate
`relatively large areas, while precise adjustment can be made
`to the difficult sites with the narrow blades, all while using
`the usual number of blades. ‘his ensures that the diseased
`tissuc is completely irradiated, while vital tissuc 1s shiclded
`from radiation and so remains undamaged. Thus the inven-
`tion incorporates the advantages of the blade collimators
`knownto priorart; it has the good adjustability of the narrow
`blades and the adequate irradiation field size of the wide
`blades, while compensating for the disadvantages described
`above.
`A blade collimator according to the invention can be
`designed in several advantageous ways.
`In onc embodiment, several adjaccnt blades are grouped
`in sets of uniform width. This configuration is especially
`well suited to objects requiring irradiation having a contour
`that is highly irregular in at least one area, but that is regular
`in other places, so that sets of the narrower blades can cover
`the irregular site, while sets of the larger blades cover the
`regularly shaped contours.
`In another advantageous embodiment, the widih of the
`bladesin the collimator increases from inside to outside. The
`shape of many tumors is characterized by irregular contours
`near the center. A collimator whose blade width increases
`from inside to outside can be especially well adjusted to such
`tumors, while the tumors may occupy larger areas. Withthis
`designin particular, the width arrangement of the blades can
`be symmetrical to an axis of symmetry lying in the direction
`of travel. In this way, the drive with its activating elements
`can be executed regularly and therefore inexpensively in
`terms of design, while a wide range of application is
`maintained for using the collimator.
`The possible means for adjusting the blade positions for
`the collimator according to the invention range from shifting
`byhand, through adjustment to a preformed contour model,
`
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`

`

`5,889,834
`
`3
`to very expensively operated adjustment and activating
`mechanisms. In one embodimentof the invention, devices
`are mounted on the blade support for moving the blades
`separately or in sets; these devices are driven by electrical
`and/or mechanical devices, especially by springs, conncct-
`ing rods orelectric motors. This makesit possible to couple
`the shifting devices and their activating mechanisms to a
`control unit, which controls the activation and path adjust-
`ment of the blades by means of stored patient data, espe-
`cially data consisting of x-rays, computer tomograms or
`nuclear spin resonance tomograms. Such a control unit,
`which might operate by means of a computer, works
`together with the blade collimator according to the invention
`to facilitate precise adjustment to the irradiation contour,
`especially when radiation comes from various directions.
`Patient data or contours of the type described above are
`three-dimensional, so that the computer can adjust the blade
`collimatorto the calculated contour with a goodfit from any
`direction of exposure.
`the sets of 2
`In another embodiment of the invention,
`blades are arranged with their support or such that they
`rotate relative to the support. The rotation of the entire array
`(i.c. the sets of bladcs with the support or the scts of blades
`on the support) makes possible a further improvementin the
`adjustability of the exposure boundary to the contour to be
`irradiated. Through such rotation, one can ensure that the
`narrower blades come to rest on irregular points of the
`contour, while regular sites are covered by wide blades.
`Connected with a sensor, which via the control unit monitors
`both the contour of the object
`to be irradiated and the
`rotational angle of the blade arrangement, such adjustments
`can be carried out under computer control.
`While the preceding discussion has assumed that the
`blades are permanently mounted on their support, another
`design according to the invention is conceivable in which
`the blades come as modules so that sets of them are
`interchangeable. With the usc of an activating and shifting
`mechanism suited to all blade modules,a still wider range of
`adjustment to the size and/or contour of the object to be
`irradiated can be ensured through the selection of sets of
`blades of appropriate width.
`Possible end-on radiation through the sets of blades can
`be prevented by giving them a special shape. In particular,
`blades designed according to the invention can be equipped
`with interlocking teeth on their side faces. Another possi-
`bility is to make usc of overfocusing; in othcr words, to
`design the blades such that they are leak-proof and have a
`prismatic shape relative to an imaginary radiation source,
`wherebythe imaginary radiation source lies higher than the
`actual radiation source used in the treatment. This yields
`better radiation absorption in the actual irradiation process.
`In another preferred embodimentof the blade collimator
`according to the invention, an additional blade is inserted
`between two blades; the former is positioned by means of
`mechanical devices such that its front face according to the
`direction of travel of the blades always occupies an essen-
`ially intermediate position between the front faces of the
`wo adjacent blades. In this configuration, the number of
`activating and control mechanisms, as well as the weight,
`can be reduced, because only every other blade requires a
`drive. Yet this arrangementretains the good adjustment to
`he contours without the otherwise usual formation ofsteps.
`Preferably,
`the sets of blades of a blade collimator
`according to the invention consist of 20 to 32 blades, with
`a preferred embodiment equipped with 26 blades. One
`advantageous configuration for 26 blades would be to
`arrange the blades symmetrically from the outside to the
`
`3o
`
`35
`
`40
`
`
`
`55
`
`60
`
`65
`
`4
`inside so that three blades 4 mm in width, three blades 3 mm
`in width and seven 2 mm in width are provided for eachside.
`A configuration such as this is low in overall weight, easily
`controllable, and can block out relatively large irradiation
`contours with a very goodfit.
`Very narrow sets of blades, which in the case of the
`configuration according to the invention come into play
`when very narrow blades of uniform width are used, can
`entail a problem with secondary position measurement.
`Such secondary position measurements are especially
`needed when motor-driven sets of blades are used.
`The drive motors have an encoder which can report back
`the primary blade position; in troublesomecases, the motors
`can cxccute turns, even when the corresponding blade stops
`for any reason, as when it locks up. After such “no-load
`racing,” the encoder reports a position that does not match
`the real position of the blade. In order to adjust for this
`mistake, blade collimators have a secondary position mea-
`surement device that ascertains the real position of the blade
`via rods connected to the blades; the ends of these rods
`communicate with individual movable contacts. These rods,
`as well as the movable contacts, occupy adjacent positions
`in a relatively wide layout that is necessitated by design
`considerations.
`the latter
`Normally,
`in collimators with wide blades,
`could be connected in a simple manner(e.g. directly) to the
`straight rods of the position measurement device. With
`narrow blades, which entail blade areas that are much
`narrower than the overall array of rods belonging to the
`secondary position measurement device, this is not possible.
`In terms of the invention, this problem is solved by a
`blade collimator characterized by individual blades whose
`upper edges, towards the back, are equipped with oblong
`connecting cords whose other ends engage the rods of a
`secondary position measurement device; seen from the
`direction oftravel of the blades, the connecting cords spread
`out upwards in roughly a fan shape up to the rods’ contact
`points, which are more widely separated than the blades.
`In this design, the connecting cords are made of flat
`strips, especially metal strips, which bend in their course
`from the edges of the blades to the contact points on the rods
`of the position measurement device and whose end segments
`are preferablystraight.
`Secondary posilion measurement can be carried out at
`any time with the solutions described above, even with very
`narrow blade ficlds.
`Another problem with narrow blade collimators of this
`type, in which the blades have tapped holes in the direction
`of travel where threaded rods turn during the adjustment
`operation,
`is that narrow blades can accommodate only
`small tapped holes. However, the small-diameter threaded
`rodsthatare inserted into these holes are unstable, especially
`if one recalls that in the vertical position, the weight of a
`blade made of tungsten rests on the threaded rod and that
`frictional forces also come to bear during movement.
`Although the usual blades are offset for radiation shield-
`ing and conveyance by each other, this does not permit the
`tapping of larger-diameter holes because the individual
`sections of the blades all have the same limited thickness.
`The blade collimator according to the invention is
`designed to solve this problem, and for this purpose is
`characterized by blades which, seen from the direction of
`travel, exhibit from top to bottom a cross-sectional shape
`with widened scctions on both sides of the bisecting line of
`the individual blades, and matching narrowed sections. In
`each case, the adjacent, identically shaped blades exhibit
`their widened sections and narrowed sections at correspond-
`
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`

`5,889,834
`
`5
`ing longitudinally displaced sites, so that the side faces of
`the blades nestle against each other in essentially flat con-
`lact. Preferably, holes are tapped as counterparts to a drive-
`threaded rod in each of the widened cross-sectional areas of
`the blades.
`This offset configuration of the blades makesit possible
`to bring the individual blades into proper position relative to
`one another, to provide radiation shielding perpendicular to
`the direction of travel, as well as the tapping of larger-
`diameter holes and thus an increase in stability. Furthermore,
`with this symmetric design, sets of blades can be deployed
`on both sides of the collimator;
`the blades of opposing,
`identically shaped sets can slide by each another with ease
`as necded.
`The arrangement and housing of the separate drive
`motors presents another problem in the blade collimators
`described above, with their narrow blade configuration.
`Electric motors with diameters ofless than approximately 16
`mm are not commercially available. Although the motors are
`arranged in a height-staggered configuration, it is not pos-
`sible to reach each blade in a small blade area in a straight
`line via drive shafts and drive threaded rodsthat are attached
`to the motors. The only traditional solution is to utilize
`flexible threaded rods, which must be made of plastic.
`Unfortunately, they are unstable, and generate abrasion that
`can impair or stop the movementofthe blades. Use of grease
`can clog up the entire apparatus with prolonged use.
`This problem too can be solved by a blade collimator
`according to the invention in which the blades are moved by
`electric motors and each electric motor has a drive shaft and
`a drive threaded rod; the problemis solved bystaggering the
`motors one behind the other in the direction of travel of the
`blades.
`Such a longitudinally staggered configuration of motors
`
`ermits every blade to be driven with a threaded rod running
`
`
`
`in a straight line. More than sufficient room remains between
`motors arranged in the same longitudinal position to permit
`he drive shaft or the threaded rod of a motor situated behind
`it to pass through.
`Embodiments of the blade collimator according to the
`invention are described more fully below with reference to
`he attached figures.
`FIG. 1 is a major cross-section of a blade configuration
`belonging to a blade collimator depicted as an embodiment
`of the invention;
`FIG. 2 shows a vicw of a sct of blades of a collimator
`according to the invention in the direction of travel of the
`blades with connecting strips mounted on the upperside of
`he blades, and these connecting strips engage a position
`measurement device; and
`FIG. 3 is a schematic diagram of a staggered configura-
`ion of motors according to the invention.
`FIG. 1 showsa left set of blades 1 and a right set of
`blades 2. ‘lo simplify the illustration, each set of blades is
`shown with only 16 blades, whercas the collimators accord-
`ing to the invention that are normally produced can have
`very many more blades. The configuration of blades
`depicted in the drawing is variable as regards their displace-
`ment. [lowever, there is a symmetrical number of blades
`relative to two perpendicular axes. The blades in each set can
`be grouped in sets 3, 4 and 5 of uniform width; due to their
`symmetrical arrangement, they are labelled with references
`only in one comer of the drawing.
`Eachsetof blades 1, 2 consists of four outer wide bladcs,
`six medium-width blades adjoining them, and six inner
`narrow blades, which in this manner comprise the outer
`blade sets, the middle blade sets 4 and the inner blade sets 5.
`
`
`
`boan
`
`3o
`
`35
`
`40
`
`50
`
`55
`
`6oa
`
`65
`
`6
`The blades are depicted in section on the right andleft
`sides of the drawing. Adjustment devices (not shown),
`which engage the left and right terminal faces of the indi-
`vidual blades (also not shown), are driven by activating
`mechanisms such as electric motors.
`In this drawing, the blades are shifted toward the middle
`of the collimator from left and right for irradiation of tumor
`contour K. Contour K is drawn in and hatched for purposes
`of illustration.
`The blades are shifted for radiation shielding to match
`the contour of the tumor, so that the inner open area is
`irradiated, while the region shielded by the blades remains
`unexposed, Although the blades are moved separately, they
`can be groupedin blade scts 3, 4 and 5 as described above.
`It is evident that the narrow blades contained in set 5 run up
`against the central part of the tumor, which has a very
`irregular contour. This permits a very good match of the
`radiation shielding to this irregular contour; only very small
`“stair-shaped”radiation steps remain, which meansthe vital
`tissue can be protected very well. For the somewhat less
`irregular contour in the outer middle range,
`the medium-
`width blades of set 4 provide an adequate fit, while the wider
`bladcs of blade sect 3 provide a very good match to the
`regular contours of the outer part of the tumor.
`Rotation ofthe blade field brings it into the best possible
`position for the tumorto betreated.It is clear that a variation
`in the width of the blades facilitates excellent adjustment to
`a contour with the narrow blades, whereas the deployment
`of medium-width and wide blades permit shielding of con-
`tours of relatively large dimensions.
`The use of traditional blade collimators with blades of
`uniform width would present great difficulties in the case
`presented here, becauseif these blades were very narrow, the
`collimator would have to be kept small due to the limited
`selectionof blades, meaning that the entire area could not be
`irradiated. Although in this case the use of traditional wide
`bladcs of uniform width could cover the entire arca of
`exposure, large radiation leaks would occur in areas with
`irregular contours, thus exposing vital tissue to damaging
`radiation.
`The collimator according to the invention solves these
`problemswithits blades of varying width, and combinesthe
`advantages of both classes mentioned above, as becomes
`clear in the illustrated embodiment.
`FIG. 2 shows a view of a set of blades belonging to a
`collimator according to the invention in the direction of
`travel of the blades with connecting strips that engage a
`position measurement device and are mounted on the upper
`side of the blades.
`In the blade collimator depicted here, oblong connecting
`cords (21) are mounted on the upper edges, toward the rear,
`of the individual blades; the other ends of these connecting
`cords engage the rods of a secondary position measurement
`device, which is not shown, via a mechanism such as a ball
`connector (27). Seen from the direction of travel of the
`blades, the connecting cords (21) spread out upwards in
`roughly a fan shape to meet contact points on the rods, which
`are more widely separated than the blades. The connecting,
`cords (21) consist of flat metal strips that bend in their course
`from the edges of the blades to the contact points on the rods
`of the position measurement device (the bend runs perpen-
`dicular to the plane of the drawing and is therefore not
`visible); the end segments of these strips are straight.
`Onc method of connecting the lower ends of the mctal
`strips to the blades is by soldering.
`FIG. 2 also shows that the blades, as seen from the
`direction of travel, exhibit from top to bottom a cross-
`
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`5,889,834
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`7
`sectional shape with widened sections (23) on both sides of
`the bisecting line of the individual blades, as well as
`matching narrowed sections (22). In each case, the adjacent,
`identically shaped blades have their widened sections (25)
`and narrowed sections (26) at corresponding, longitudinally
`displaced sites such that the side faces of the blades nestle
`against each other in essentially flat contact. Tapped holes
`(24) as counterparts to a drive-threaded rod are found in the
`widened cross-sectional areas of each blade. They can be
`relatively wide in diameter and therefore accommodate
`stable threaded rods.
`FIG. 3 is a schematic diagram of a staggered motor
`configuration of the invention. In a blade collimator in which
`the blades are driven byelectric motors (31, 34) and the
`electric motors each have a drive-shaft (32, 35) and a
`drive-connecting rod (33, 36),
`the motors (31, 34) are
`arranged in a slaggered pattern one behind the other in the
`direction of travel of the blades. Depending on the number
`of motors, the stagger can be two-stepor, as illustrated here,
`three-step. ‘he stagger can of course havestill more steps in
`the longitudinal direction. The motors are also usually
`height-staggered—thatis, staggered in the direction perpen-
`dicular to the plane of the drawing.
`It is clear from the schematic diagram of FIG. 3 that with
`a configuration suchasthis, the shaft (32) or the threaded rod
`(33) can pass between the two motors lying in front of it with
`ease, thus permitting a linear drive for the blades.
`We claim:
`1. Blade collimator for radiation therapy, comprising a
`support device,
`two opposing sets of blades mounted in one layer in said
`support device, each blade capable of reciprocable
`movementin said support device and having a dimen-
`sion perpendicular to the movement,
`each set of blades comprising a central blade adjacent to
`the bladesof the other set, an exterior blade, and a blade
`interposed between the central blade and the exterior
`blade, the dimensionof the exterior blade being greater
`than the dimension of the interposed blade and the
`dimension of the interposed blade being greater than
`the dimension of the central blade.
`2. Blade collimator according to claim 1 in whichthe
`dimensions of several adjacent blades of cach sct are equal.
`3. Blade collimator according to claim 1 in which the
`blades are leak-proof against radiation by meansof recip-
`rocal interlocking of teeth.
`4. Blade collimator according to claim 1 in whichthe
`dimensions of the respective blades are symmetrical to an
`axis of symmetry in a direction of the movement.
`5. Blade collimator according to claim 1 in which mecha-
`nisms for moving the blades separately or in sets are
`mounted on the blade support, and the mechanisms are
`activated by at
`least one of electrical and mechanical
`devices.
`6. Blade collimator according to claim 5 in which the
`devices are coupled to a control unit
`that controls the
`activation and path adjustment of the blades by means of
`stored patient data.
`7. Blade collimator according to claim 6 in which the sets
`of blades are arrayed with thcir support or such that they
`rotate relative to it.
`8. Blade collimator according to claim 1 in which sets of
`blades in modular form are interchangeable.
`9. Blade collimator according to claim 1 in which the
`blades arc leak-proof against radiation by means of overfo-
`cusing.
`10. Blade collimator according to claim 1 in which an
`additional blade is inserted between two blades and the
`additional blade is positioned by mechanical devices such
`
`3o
`
`35
`
`40
`
`50
`
`55
`
`60
`
`65
`
`
`
`8
`that its front face in the direction of movementofthe blades
`always occupies an essentially intermediate position
`between the front faces of the two blades adjacentto it.
`11. Blade collimator according to clam 1 in which the
`sets of blades consist of from 20 to 32 blades.
`12. Blade collimator according to claim 11 with 26 blades
`in which eachset has:
`3 blades 4 mm in width,
`3 blades 3 mm in width and
`7 blades 2 mm in width.
`13. Blade collimator according to claim 1, in which an end
`of oblong connccting cords arc mounted on upper cdges,
`toward the rear, of the individual blades, whereby other ends
`of the connecting cords cngage rods of a secondary position
`measurementdevice and the connecting cords, seen from the
`direction of movementof the blades, spread out upwards in
`roughly a fan shape to meet contact points on the rods, which
`are more widely separated than the blades.
`14. Blade collimator according to claim 13 in which the
`connecting cords consist of flat strips that bend in their
`course from the blades to the contact poimts on the rods of
`the position measurement device.
`15. Blade collimator according to claim 1, in which the
`blades, as seen from the direction of movement, exhibit from
`top to bottom a cross-sectional shape with widened sections
`on both sides of a bisecting line of the individual blades, as
`well as matching narrowed sections, whereby the adjacent,
`identically shaped blades exhibit their widened sections and
`narrowed sections at corresponding longitudinally displaced
`positions, so that the side faces of the blades nestle against
`cach adjacent blade in essentially flat contact.
`16. Blade collimator according to claim 15 in which
`tapped holes as counterparts to drive threaded rods are
`created in the widened cross-sectional areas of each blade.
`17. Blade collimator according to claim 5, in which
`the blades are moved by electric motors, and
`the electric motors each have a drive shaft and a drive
`threaded rod, whereby
`the motors are arranged one behind the
`staggered configuration in the direction 0
`of the blades.
`18. Blade collimator according to claim 13, in which
`the blades are moved by electric motors, and
`the electric motors each have a drive shaft and a drive
`threaded rod, whereby
`the motors are arranged one behind the
`staggered configuration in the direction 0
`of the blades.
`19. Blade collimator according to claim 15, in which
`the blades are moved by electric motors, and
`the electric motors each have a drive shaft and a drive
`threaded rod, whereby
`the motors are arranged one behind the
`staggered configuration in the direction 0
`of the blades.
`20. Blade collimator according to claim 5 in which the
`mechanismsare activated by springs.
`21. Blade collimator according to claim 5 in which the
`mechanismsare activated by connecting rods.
`22. Blade collimator according to claim 5 in which the
`mechanismsare activated by electric motors.
`23. Blade collimator according to claim 5 in which the
`stored patient data includes at least one of x-rays, computer
`tomogramsor nuclear spin resonance tomograms.
`24. Blade collimator according to claim 14 in which the
`connecting, cords consist of flat metal strips, and whose end
`segments are straight.
`
`
`
`other in a
`movement
`
`other in a
`movement
`
`other in a
`movement
`
`ViewRay Exhibit 1028
`Page 8 of 8
`
`ViewRay Exhibit 1028
`Page 8 of 8
`
`