CA1097436A - Tube for irradiation equipment - Google Patents
Tube for irradiation equipmentInfo
- Publication number
- CA1097436A CA1097436A CA300,284A CA300284A CA1097436A CA 1097436 A CA1097436 A CA 1097436A CA 300284 A CA300284 A CA 300284A CA 1097436 A CA1097436 A CA 1097436A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- carrier plate
- lamella
- baseplate
- side wall
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000000670 limiting effect Effects 0.000 claims abstract description 26
- 230000005540 biological transmission Effects 0.000 claims abstract description 20
- 238000006073 displacement reaction Methods 0.000 claims abstract description 7
- 230000000284 resting effect Effects 0.000 claims abstract 5
- 241000446313 Lamella Species 0.000 claims description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 239000003990 capacitor Substances 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 238000010521 absorption reaction Methods 0.000 claims description 4
- 239000000969 carrier Substances 0.000 claims description 4
- 230000005855 radiation Effects 0.000 claims description 2
- 238000010894 electron beam technology Methods 0.000 description 11
- 238000002560 therapeutic procedure Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 238000009432 framing Methods 0.000 description 2
- 229910000897 Babbitt (metal) Inorganic materials 0.000 description 1
- 235000012571 Ficus glomerata Nutrition 0.000 description 1
- 240000000365 Ficus racemosa Species 0.000 description 1
- 235000015125 Sterculia urens Nutrition 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229940000425 combination drug Drugs 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000033001 locomotion Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000001225 therapeutic effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/54—Control of apparatus or devices for radiation diagnosis
- A61B6/548—Remote control of the apparatus or devices
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Radiation-Therapy Devices (AREA)
- Apparatus For Radiation Diagnosis (AREA)
- Particle Accelerators (AREA)
Abstract
TITLE OF THE INVENTION:
TUBE FOR IRRADIATION EQUIPMENT
ABSTRACT OF THE DISCLOSURE
A tube for irradiation equipment for limiting an emergent beam, with a baseplate, possessing a central aperture, intended for attaching to the equipment, as well as four carrier plates, each of which possesses a limiting edge and a sliding edge located at right angles thereto. The carrier plates are located parallel to the baseplate, the limiting edge of each carrier plate resting against the sliding edge of the adjacent carrier plate and each of the two mutually opposite pairs of carrier plates being displaceable, parallel to the direction of its sliding edges and symmetrically to the center of the transmission aperture, for the purpose of continuously varying the transmission aperture defined by the limiting edges, during which displacement each of the displaced carrier plates carries with it the carrier plate, resting against the limiting edge of the former plate, parallel to the direction of the limiting edge of the latter plate.
TUBE FOR IRRADIATION EQUIPMENT
ABSTRACT OF THE DISCLOSURE
A tube for irradiation equipment for limiting an emergent beam, with a baseplate, possessing a central aperture, intended for attaching to the equipment, as well as four carrier plates, each of which possesses a limiting edge and a sliding edge located at right angles thereto. The carrier plates are located parallel to the baseplate, the limiting edge of each carrier plate resting against the sliding edge of the adjacent carrier plate and each of the two mutually opposite pairs of carrier plates being displaceable, parallel to the direction of its sliding edges and symmetrically to the center of the transmission aperture, for the purpose of continuously varying the transmission aperture defined by the limiting edges, during which displacement each of the displaced carrier plates carries with it the carrier plate, resting against the limiting edge of the former plate, parallel to the direction of the limiting edge of the latter plate.
Description
7~3~>
¦! TUBE FOR IRRADIATION EQUIP~IENT
BACKGROUND OF TIIE INVENTION
¦ The present invention relates to a tube for irradiation equipment for limiting an emergent beam.
The term irradiation equipment is in particular applied, in the text which follows, to particle accelerators, electron accelera-tors, gan~na irra- ¦
diation equipment and X-ray equipment. For therapeutic and diagnostic use it is essential to limit the cross-section of the beam emerging from the I i.rradiation equipment to the requisite minilllum and to screen off the irradia-I tion effectively, at the sides, between the outlet aperture of the irradia-tion equipment and the surface of the article to be irradiated. At the sall~etime, when using an electron accelerator the proportion of the secondary X-¦¦ rays and scattered electrons produced by the high speed electrons in the I diaphragm system, and manifesting itself outside the actual field of irradia-¦ tion, should be kept as low as possible in order to reduce the side-effect of the irradiation.
As a further condition, it shollld be possible to choose as many varia-tions of field dimensions as possible withill the range of ~ield sizes imposed ¦ by the irradiation equipment. For this reason a variety of devices have also I already been disclosed and are used with which the cross-section of the ¦ irradiation can be limited and the beam can be screened off laterall ~.
A first known device consists of a set o-f diaphragms, of which each is firmly fixed to a tube. The diaphragm and tube can be fixed detachably to I the casing of the electron accelerator. For example~ the diaphragllls are in ¦ the form of thick lead sheets which have a central aperture which limits the cross-section of the emergent electron beam. The tube serves to limit the electron beam and screen it oFf laterally. This relatively si Dlp le device~
I . I
~1 -2-~097436 suffers from several disadvantages. It is only possible to adjust the beam to fixedly predetermined cross-sections, and the exchangeable diaphragms with attached tube require a great deal of storage space, are expensive, are diffi-cult to handle because of their weight, and must, whenever a change in beam I cross-section is necessary, be exchanged, thereby consuming a relatively large ¦l amount of time.
Another known device comprises a baseplate on which several diaphragms I are located in succession in the direction of the beam. Each of these dia- ¦
¦ phragms has several diaphragm blocks continuously displaceable at right angles¦
¦ to the direction of the beam. This device permits continuous variation of ¦
the diaphragm cross-section and hence of the effective electron beam and does ¦
I not require an additional tube. A disadvarltage of this device is tllat because II of the diaphragms being arranged in sUCcession, a part of the fast electrons ¦¦ is screened off near the object to be irradiated, as a result of which a rela-~ ¦ tively high proportion of gan~lla radiation and secondary electrons is liberated,WhiCtl must be avoided particll1arly in the case of radiatioll therapy, and that if the diaphragm aperture is smal.l the diaphragill blocks project beyond the ¦ cross-section of the useful electron beam, which makes it difficult, or even ¦¦ impossible, to introduce the device into recesses and, for example, to irra-¦I diate the armpits or the throat.Il . Further, a device is already known Which possesses a variable diaphragm ¦¦ built into the accelerator casing, and corresponding tubes of different cross-¦
Ij section which can be attached to the accelerator housing. In this device, ¦I the advantages of the variable diaphraglll can only be utilized partially be-il caus.e the diaphragln must necessarily be set to the dimensions of the available¦I tubes. Furthermore, this device suffers from all disadvantages already men-¦ tioned above for exchangeable tubes.
Il -3-l! I
SU~l~lARY OF THE INVEN~ION
Accordingly, it is the object of the present invention to provlde a tube for irradiation equipment, which tube is of infinitely variable cross-section,¦
¦ and in which the external dimensions of the free end are only slightly greater ¦ than the dimensions of the free aperture at the end of the tube, in order to permit, as far as possible, unhindered approach to the object to be irradiated ll According to the invention, this object is achieved by means of a tube li of the initially described type, whicll is characterized in that on each car-¦¦ rier plate there are provided a side wall and at least one equally high lamel-¦! la, which side wall projects, at the side of the limiting edge which abuts thejsliding edge, at right angles from the carrier plate and which lamella or ¦
lamellae is or are pivotably fastened in the region of the limiting edge and can be laid down on the carrier plate or be erected, as an extension of the side wall, in order to form a side wall of a tube of variable cross-section.
The ne~ tube can be fed to any quadranglllar cross-sectioll Witil dimensions between a minilllum square, the side length of which corresponds to the length of one side wall, and a maximum square, the side length of which corresponds ¦ to the length of one side wall and of the corresponding lamellae. Because Il the lamellae not required to form the tube side walls are laid down on the 1I carrier plates, the external cross-section of the tube is only slightly great-l ¦ er than the internal cross-section, thereby permit-ting unhindered introduction¦
¦l of the tube into recesses. I
! For simpler manual adaptation of the tube walls to the selected cross-Il section, a plurality of magnets can be fixed to each carrier plate, which I magnets hold the lamellae laid down on the carrier plate, while a spring can engage agains~ the base of each lamella, which spring pivots the lamellae, re-~1 4 li .
l I
I . I
:~197436 leased by the holding magnets, into the erect position.
In a preferred embodiment, further measures are provided whicll, on adjust-1 ing the tube cross-section, automatically raise the lamellae or lay them down¦l on the carrier plate. For this purpose there is fixed to each carrier plate¦ along the extension of the lin]iting edge, a tongue, which carries on its end ¦¦ projecting onto the adjacent carrier plate a stop of which one side face rests ¦ against the adjacent erect lamella and prevents its pivoting into the laid-¦ down position, while its other side face has a wedge-shaped challlfer and is I ; -¦ pushed under the adjacent laid-down lamella and, on displacing the carrier ¦ plate in order to increase the transmission aperture, lifts this next lamellaoff the holding magnet. Furthermore, an electromagnetic switch device is fix-ed on each side wall, which possesses a lever which, after the carrier plate has been displaced in order to reduce the transmission aperture, pivots the ¦l lamella adjoining the side wall, on the adjoining carrier plate, into the ¦11 laid-down pOSitiOIl.
BRIEF DESCRIPTION OF THE DRAlllNGS
1¦ A more complete appreciation of the invention and many of the attendant~¦ advantages thereof will be readily obtained as the same becomes better under- ¦
Il stood by reference to the following detailed description when considered in ¦ connection with the accompanying drawings, wherein: ¦
¦ FIGURE 1 shows the schematic representation of an accelerator window with¦
I diaphragms and a tube of the hitherto conventional type, ¦ FIGURE 2 shows the plan view of an embodiment of the new tube, FIGURE 3 shows the section along line III-III through the tube according , to Figure 2, ¦ FIGURE 4 shows the side view, partially in sec-tion, of the tube according _5_ 1~97~36 il ¦I to FIGURE 2, viewed in the direction of the arrow IV, appearing with Figs. 1 ar d 5, and FIGURE 5 shows the schematic representation of a contact switch in the I tube baseplate, appearing with Figs. 1 and 4.
Il 5 1I DESCRIPTION OF THE PREFERRED EMBODIME~TS
! Referring now to the drawings, whereill like referellce numerals designate ¦
¦ identical or corresponding parts throughout the several views, FIGURE 1 shows Il schematically the aperture of an electron accelerator with diaphragms for the I
!~ electron beam, and a tube. Accelerator 10 possesses a window 11 which is in- ¦
lo I tended to transmit a narrow electron beam. At a distance froM the window, in 1I the direction of the emergent electron beam, are located a first scatterer 12 ¦
¦¦ and a main scatterer 13 "~hich broaden the narrow elec-tron beam. In order tolimit the maxinluln diameter of the electron beam issuing from the accelerator ,I casing 14, a first diaphragm 16 is fixed within the casing. Furthermore, a 15 ¦¦ screen 17 is provided, which screens off an anterior diaphragm 18, located in r ¦¦ the region oF the aperture of the casing, and possesses a central aperture 19¦¦ through which the electron beam emerges from the accelerator casing. This ¦I central aperture is framed by a holder device 21, into which an exchangeable Il tube 22 is inserted.
20 I¦ In order to adapt the cross-section of the electron ~eam emerging from ` ¦I the tube to the intended use, it is possible to use, in this arrangement, anterior diaphragms 18 of different free internal cross-sections or a fixedly ¦l built-in anterior diaphraglll with a variable free internal cross-section, as I well as to use exchangeable tubes matching these cross-sections.
I The embodilnent of the tube of variable cross-section, according to the invention, shown in Figures 2 and 3 is built up on a baseplate 30. The base-plate is intended for fixing to the screen 17 and has a large central aperture 1 .
~1 ' I .
:~97~36 ' ~ ' I
¦ 3l. Four carrier plates 32, 33, 34 and 35 are located on the baseplate. Each ¦ carrier plate has at least two edges located at right angles to one another, ¦ namely a limiting edge 37, 3~, 39 or 40 and a sliding edge 42, 43, 44 or 45.
¦ The carrier plates are so located relative to one another that the parts of I the limiting edges which adjoin the sliding edges form the frami1lg of a trans-I mission aperture 47 and the ren~aini1lg part of each limiting edge rests againstj ! the sliding edge of an adjacent carrier plate. The carrier plates can be dis-¦placed parallel to the plane of the baseplate by means of a displacement de-Il vice customary for adjustable anterior diaphragms, which device is known to ¦I those skilled in the art and is therefore only indicated with broken lines 50, 51. This displaceme1lt device permits each oF the two pairs of carrier platesJ
formed by mutually opposi-te carrier plates 32, 34 or 33, 35, to be displaced ¦ syn~netrically to the center of the transmission aperture 47, independently of ¦
I¦ the other pair of carrier plates, and in the direction of its sliding edge.
lS ~¦ During this displacement, the two carrier plates of the other pair of carrier 11 plates are carried with the first pair, so that the contact between adjacent j carrier plates and the framing of the transmission aperture always remains I1 preserved. If, for example, the carrier plates 33, 35 are pushed apart, the ¦¦ carrier plate 34 follows the displacement of the carrier plate 33 and the car-rier plate 32 follows the carrier plate 35. In this way, the square trans 1 -~
mission aperture 47 shown in Figure 2 can be reduced and enlarged or be re- ¦
shaped into an upright or horizontal rectangle of any desired dimensions.
! As can be seen most clearly in Figure 2, a side wall 53, 54, 55 or 56 1l projects from each carrier plate. Each side wall is located along the limit-ing edge and one of its lateral edges terminates in the corresponding sliding ¦ edge af the carrier plate. Each side wall stands at right angles to the carrier plate and the four side walls form a closed tube if the four carrier -~
~ i1 li .
~L~97436 ll l ~¦ plates are pushed together sufficiently far that in their limiting edges frame¦
¦ the smallest envisaged transmission aperture. In the lateral extension of each side wall, and above the limiting edge, there is additionally fixed a I thin shaft 60, 61, 62 or 63. On this shaft a plurality of lamellae are pivot-ably mounted, of which, for clarity, only lanlellae 69 to 71 on the shaft 60 of the carrier plate 32 are identified by reference nunlbers. All lamellae can be pivoted between a laid-down position in which they are located virtually l parallel to the surface of the carrier plate, and an erect position, in which ¦I they are located parallel to the side wall. In FIGURES 2 and 3, the lamellae ¦¦ 65 to 68 on the carrier plate 32 (and the corresponding lamellae of the other !
¦I carrier plates~ are drawn in the erect position, and the lanlellae G9, 70 and ¦ r ¦ 71 on the carrier plate 32 (as well as the correspolldillg lamellae of the other carrier plates) are drawn in the laid-down position. As will be immediately I obvious to anyone skilled in the art, it is possible, by erecting those lanle-llae which are located along the parts of -the limiting edges which form the framing of the transmission aperture, to form a tube the internal cross- ¦ r section of which is virtually of the same size ancl the same shape as the cross-section of the transmission aperture. Because the lamellae not requiredl for broadening the tube walls relnain in their laid-down position, the externalj cross-section of the free end of the tube ;s not much larger than its internal cross-section, that is to say, the cross-section of the electron beam which . ¦ emerges through the tube. This construction makes it possible to introduce ¦I the free end of the tube "Yithout hindrance by projecting side pieces, even ¦ into recesses. As has already been described above, this is particularly im-25 ¦ portant when using irradiation equipment in medicinal diagnostics and therapy,¦
for example if the tube is to be brought into an armpit or against the neck ol a pe ent.
. . .
I I , ,_- ;
~L09~436 If the transmission aperture is set -to a dimension which does not corres-~pond to the grid predetermined by the lateral length of the lamellae, the lastl -erect lamella of each side wall projects partially beyond the corner of the tube. This apparent disadvantage is virtually of no importance if the lateral 5` length of the lamellae is not great. I
As can be seen best in Figure 4, each lamella consists of a steel strip 75, at one lengthwise end of which is located a lamella base 76, while in the ,region of its other lengthwise end there are located several absorption pieces ¦1 77, 78 and 79. The lamella base preferably consists of bearing metal and has ¦! a bore 81, by rneans of which the lamella is pushed onto the shaft 60. The absorption pieces are in particular intended to absorb secondary X-rays ancl Il stray electrons. In a combina-tion whicil is particularly suitable for this iI purpose, the absorption pieces 77, 7~ and 79 consist of light metal, steel or~ Antikorrodal.
1 In the embodiment of the new tube shown in the figures, a plurality of ! small permanent magnets is located on eacll carr-ier pla-te, among which, for l! clarity, only magnets 83 to 89 on carrier plate 32 are identified by refer-il ence numbers. These permanent magnets are provided in orde,- to hold the i~ lamellae which have been laid down on the carrier plate.
As may be seen from Figure 2, the lamellae overlap in cross-section. The result of this is that the tube wall cori~posed of adjacently located lamellae I! is "tight" and that none of the erect lamellae can be laid down as long as ¦, the last erect lamella is locked in its position. For this purpose, a thin ¦ tongue 92 is fixed to each carrier plate (Figure 4) which tongue projects, in ¦ the extension of the limiting edge 38, beyond the adjacent carrier plate 32, 1 ;
¦ and carries a stop 90. This stop rests, with one of its sides, against ;the particul r last lamella 66 of a tube wall, and thereby prevents this lamelld ll li , !! l 7~
¦ from being pivoted ~rom the erect p~sition into the laid-down position. pre- I -¦¦ ferably, this stop is wedge-shaped in the direction of the sliding edge. Thismakes it posssible, when displacing a pair of carrier plates in order to i enlarge the cross-section of the framed transmission aperture 47, to slide 1I the stops, fixed to the two displaced carrier pla-tes, with their wedge-¦¦ shaped surfaces under the lamellae 69 of the adjacent carrier plates 32 and to lift these lamellae off the permanent magnets 87.
To each lamella there is allotted a spring 91 which engages in the region ¦ of the base of the lamella (Figure 4) and pivots it into the erect position ¦ as soon as it has been released from the holding magllet.
In the shown embodilllen-t o-f the tube there is furtherlllore located, on the ¦¦ outside of each side wall 54, an electromagnetic switch device 93 which com-prises a lever 94 which has a virtually vertical rest position and can be I pivoted through about 90 into the working position sho~qn with broken lines ~ in Figure 4. After displacing one pair of carrier plates ;n order to reduce ¦I the cross-section of the transmissioll aperture, the switch devices on the side walls of the displaced carrier plates are actuated, whereupon in each cas~
¦ the last lamella of the adjacent tube wall is pivoted into its laid-down j'l position and is held by the corresponding permanent magnet. Because of the ¦¦ mutual overlap of the lamellae, which has already been mentioned above, laying ¦I down one lamella results in all further lamellae automatically being laid down 1 in the direction facing away from the corresponding side wall. This ensures jl that on reducing the cross-section of the transmission aperture all lamellae lii no longer required to form the tube have been laid down on the corresponding ¦ ¦
ijl carrier plate.
I ¦1 As has already been described above, it is necessary, when using irradia- I
1¦ tion equipment for diagnostics and therapy, to briny the free end of the tube t l! .
Il -10-li I
li . ¦
: ` `
~L097~36 ~ `
as close as possible to the object or to the patient. Because of the large weight of the entire installation, special drive motors are used for the re-quired displacement motions or rotary motiolls of individual parts of the equip ment. In order to ensure that these drive motors are switched off as soon as the tube has been brought to a minimum distance from the patient, special ¦ proximity switches are used. In a first embodiment of such a safety device, ¦
I an insulated electrode 100 is fixed to the free end of each side wall. The il electrodes, numbering four in total, are preferably wired electrically in ¦¦ parallel, and form a capacitor with the tube. This capacitor is connected, ¦I in a known manner, to an HF measuring bridge which is put out of balance as ¦I the tube approaches a patient and switches off the feed voltage for the drive¦ motors! via a comparator/trigger circuit, when a presettable unbalance has been reached.
Il In another embodilnent of this safety device, the baseplate of the tube 11 is fixed in an insulated manner to the accelerator casing, and the entire tube ¦l is used as a capacitor electrode.
In yet another embodinlent, the safe-ty device is actuated not on approach-¦
ing, but only on touching, the object to be irradiated. As is shown schematic Il ally in Figure 5, this embodinlent uses a tube insert 102 which is located ¦
¦I parallel to the baseplate 30 and can be inserted into the holding device 21.¦ A stud bolt 103, which passes through a corresponding bore in the baseplate I¦ 30, is fixed to each of the four corners of this tube insert. In addition, ¦1 an electrical switch is provided, of which one contact 104 is fixed by meansI of an insulating disc 105 to the baseplate, while its other contact 106 is ¦ fixed by means of an insulating disc 107 to the free end of the stud bolt.
Around each stud bolt is inserted, between the tube insert 102 and the base-¦ plate 30, a spring lOû which presses the baseplate away frolll the tube insert Il 11 I
1,1 ' . .
Il . .
1' :~' ¦l and presses the contac-t 104 onto the contact 106. The Four switches are preferably ~ired electrically in series. I~hen, on moYing or turnin.g the in-stallation or the patient, the tube is touched and compressed or tipped against the force of one or more springs, the contacts of the corresponding switches I are separated from one another and a safety circuit is broken and switches offi the feed voltage for the drive motors. .
In an embodiment of the new tube used in practice the side length of each ¦ side wall is 4 cm, which makes it possible to telescope the carrier plate suf-II ficiently that the minimum transmission aperture 47 corresponds to a square ¦I with sides 4 cm long. Furthermore, with this embodilllent 16 lamellae are loca-¦
¦¦ ted on each carrier plate, the side length of each lalllella being 1 cm. Accord ingly, the max;lllunl transmission aperture can be set to correspond to a square¦I with sides 20 cm long. As has already been described in detail above, any ¦I quadrangular transmission aperture with dimensions lying between the two stat-! ed extreme values can be set up with the new tube. In ti~is embodinlent, the r il height of the side walls and lamellae is 17 cm.
ii It has already been mentioned that the preliminary diaphragm 18 must be li set to the cross-section of the tube. Since the object to be irradiated de- ¦termines the cross-section of the tube, this tube cross-section is first set 20 up. This setting can be effected manually or by means of servo-motors. Pref-.. : ¦ erably, an adjust~ble anteribr diaphragm is used, and the cross-section of the ¦¦ tube as well as the apertul-e of the preliminary diaphraglll are picked up by li actual value indicators, For example potentiometers. The ac-tual values are~ ¦I then compared in comparators and the resulting error signal is used to con- ¦
~. 25 il trol the diaphragm servo-motors until the actual values for the diaphragm ll aperture corresponds to the actual values of the tube cross-section. It will ¦
be understood that in this way it is also possible to set up a non-linear re--l2-9~3~ I
lation of tube cross-section to diaphragm aperture.
In a further embodilllent of the new tube, an anterior diaphragm 1~, ¦
¦I forming part of the accelerator, is not required. In this embodinlent, the I¦ distance between the baseplate and the carrier plates is increased, and dia-¦ phragm blocks are nlounted on the surfaces, facing the baseplate, oF each car-rier plate, or the carrier plates are constructed as diaphragm blocks. It will be appreciated that with this embodinlent each adjustment of the tube ¦ cross-section simultaneously also results in an adjustment of the effective I¦ diaphragm aperture.
¦¦ Finally, it is also possible to adjust the tube cross-section and the diaphragm aperture by means of remote control from an operating panel or from ¦l a data store. Appropriate circuits are known to all those skilled in the ¦ art and will therefore not be described in detail.
l Though the new tube has been described in relation to an illustrated i embodilllent which possesses four displaceable baseplates and defines a quadran-¦¦ gular transmission aperture, it will be obvious to all those skilled in the ! art that it is also possible to construct a corresponding tube with three or , five or more baseplates which are displaceable symmetrically to one another.
ll Obviously, numerous modifications and variations of the present invention¦
¦l are possible in light of the above teachings. It is therefore to be under-stood that within the scope of the appended claims, the invention may be i practiced othei^wise than as specifically described herein.
. i~
Il ' I
ll -13-1, . I
il
¦! TUBE FOR IRRADIATION EQUIP~IENT
BACKGROUND OF TIIE INVENTION
¦ The present invention relates to a tube for irradiation equipment for limiting an emergent beam.
The term irradiation equipment is in particular applied, in the text which follows, to particle accelerators, electron accelera-tors, gan~na irra- ¦
diation equipment and X-ray equipment. For therapeutic and diagnostic use it is essential to limit the cross-section of the beam emerging from the I i.rradiation equipment to the requisite minilllum and to screen off the irradia-I tion effectively, at the sides, between the outlet aperture of the irradia-tion equipment and the surface of the article to be irradiated. At the sall~etime, when using an electron accelerator the proportion of the secondary X-¦¦ rays and scattered electrons produced by the high speed electrons in the I diaphragm system, and manifesting itself outside the actual field of irradia-¦ tion, should be kept as low as possible in order to reduce the side-effect of the irradiation.
As a further condition, it shollld be possible to choose as many varia-tions of field dimensions as possible withill the range of ~ield sizes imposed ¦ by the irradiation equipment. For this reason a variety of devices have also I already been disclosed and are used with which the cross-section of the ¦ irradiation can be limited and the beam can be screened off laterall ~.
A first known device consists of a set o-f diaphragms, of which each is firmly fixed to a tube. The diaphragm and tube can be fixed detachably to I the casing of the electron accelerator. For example~ the diaphragllls are in ¦ the form of thick lead sheets which have a central aperture which limits the cross-section of the emergent electron beam. The tube serves to limit the electron beam and screen it oFf laterally. This relatively si Dlp le device~
I . I
~1 -2-~097436 suffers from several disadvantages. It is only possible to adjust the beam to fixedly predetermined cross-sections, and the exchangeable diaphragms with attached tube require a great deal of storage space, are expensive, are diffi-cult to handle because of their weight, and must, whenever a change in beam I cross-section is necessary, be exchanged, thereby consuming a relatively large ¦l amount of time.
Another known device comprises a baseplate on which several diaphragms I are located in succession in the direction of the beam. Each of these dia- ¦
¦ phragms has several diaphragm blocks continuously displaceable at right angles¦
¦ to the direction of the beam. This device permits continuous variation of ¦
the diaphragm cross-section and hence of the effective electron beam and does ¦
I not require an additional tube. A disadvarltage of this device is tllat because II of the diaphragms being arranged in sUCcession, a part of the fast electrons ¦¦ is screened off near the object to be irradiated, as a result of which a rela-~ ¦ tively high proportion of gan~lla radiation and secondary electrons is liberated,WhiCtl must be avoided particll1arly in the case of radiatioll therapy, and that if the diaphragm aperture is smal.l the diaphragill blocks project beyond the ¦ cross-section of the useful electron beam, which makes it difficult, or even ¦¦ impossible, to introduce the device into recesses and, for example, to irra-¦I diate the armpits or the throat.Il . Further, a device is already known Which possesses a variable diaphragm ¦¦ built into the accelerator casing, and corresponding tubes of different cross-¦
Ij section which can be attached to the accelerator housing. In this device, ¦I the advantages of the variable diaphraglll can only be utilized partially be-il caus.e the diaphragln must necessarily be set to the dimensions of the available¦I tubes. Furthermore, this device suffers from all disadvantages already men-¦ tioned above for exchangeable tubes.
Il -3-l! I
SU~l~lARY OF THE INVEN~ION
Accordingly, it is the object of the present invention to provlde a tube for irradiation equipment, which tube is of infinitely variable cross-section,¦
¦ and in which the external dimensions of the free end are only slightly greater ¦ than the dimensions of the free aperture at the end of the tube, in order to permit, as far as possible, unhindered approach to the object to be irradiated ll According to the invention, this object is achieved by means of a tube li of the initially described type, whicll is characterized in that on each car-¦¦ rier plate there are provided a side wall and at least one equally high lamel-¦! la, which side wall projects, at the side of the limiting edge which abuts thejsliding edge, at right angles from the carrier plate and which lamella or ¦
lamellae is or are pivotably fastened in the region of the limiting edge and can be laid down on the carrier plate or be erected, as an extension of the side wall, in order to form a side wall of a tube of variable cross-section.
The ne~ tube can be fed to any quadranglllar cross-sectioll Witil dimensions between a minilllum square, the side length of which corresponds to the length of one side wall, and a maximum square, the side length of which corresponds ¦ to the length of one side wall and of the corresponding lamellae. Because Il the lamellae not required to form the tube side walls are laid down on the 1I carrier plates, the external cross-section of the tube is only slightly great-l ¦ er than the internal cross-section, thereby permit-ting unhindered introduction¦
¦l of the tube into recesses. I
! For simpler manual adaptation of the tube walls to the selected cross-Il section, a plurality of magnets can be fixed to each carrier plate, which I magnets hold the lamellae laid down on the carrier plate, while a spring can engage agains~ the base of each lamella, which spring pivots the lamellae, re-~1 4 li .
l I
I . I
:~197436 leased by the holding magnets, into the erect position.
In a preferred embodiment, further measures are provided whicll, on adjust-1 ing the tube cross-section, automatically raise the lamellae or lay them down¦l on the carrier plate. For this purpose there is fixed to each carrier plate¦ along the extension of the lin]iting edge, a tongue, which carries on its end ¦¦ projecting onto the adjacent carrier plate a stop of which one side face rests ¦ against the adjacent erect lamella and prevents its pivoting into the laid-¦ down position, while its other side face has a wedge-shaped challlfer and is I ; -¦ pushed under the adjacent laid-down lamella and, on displacing the carrier ¦ plate in order to increase the transmission aperture, lifts this next lamellaoff the holding magnet. Furthermore, an electromagnetic switch device is fix-ed on each side wall, which possesses a lever which, after the carrier plate has been displaced in order to reduce the transmission aperture, pivots the ¦l lamella adjoining the side wall, on the adjoining carrier plate, into the ¦11 laid-down pOSitiOIl.
BRIEF DESCRIPTION OF THE DRAlllNGS
1¦ A more complete appreciation of the invention and many of the attendant~¦ advantages thereof will be readily obtained as the same becomes better under- ¦
Il stood by reference to the following detailed description when considered in ¦ connection with the accompanying drawings, wherein: ¦
¦ FIGURE 1 shows the schematic representation of an accelerator window with¦
I diaphragms and a tube of the hitherto conventional type, ¦ FIGURE 2 shows the plan view of an embodiment of the new tube, FIGURE 3 shows the section along line III-III through the tube according , to Figure 2, ¦ FIGURE 4 shows the side view, partially in sec-tion, of the tube according _5_ 1~97~36 il ¦I to FIGURE 2, viewed in the direction of the arrow IV, appearing with Figs. 1 ar d 5, and FIGURE 5 shows the schematic representation of a contact switch in the I tube baseplate, appearing with Figs. 1 and 4.
Il 5 1I DESCRIPTION OF THE PREFERRED EMBODIME~TS
! Referring now to the drawings, whereill like referellce numerals designate ¦
¦ identical or corresponding parts throughout the several views, FIGURE 1 shows Il schematically the aperture of an electron accelerator with diaphragms for the I
!~ electron beam, and a tube. Accelerator 10 possesses a window 11 which is in- ¦
lo I tended to transmit a narrow electron beam. At a distance froM the window, in 1I the direction of the emergent electron beam, are located a first scatterer 12 ¦
¦¦ and a main scatterer 13 "~hich broaden the narrow elec-tron beam. In order tolimit the maxinluln diameter of the electron beam issuing from the accelerator ,I casing 14, a first diaphragm 16 is fixed within the casing. Furthermore, a 15 ¦¦ screen 17 is provided, which screens off an anterior diaphragm 18, located in r ¦¦ the region oF the aperture of the casing, and possesses a central aperture 19¦¦ through which the electron beam emerges from the accelerator casing. This ¦I central aperture is framed by a holder device 21, into which an exchangeable Il tube 22 is inserted.
20 I¦ In order to adapt the cross-section of the electron ~eam emerging from ` ¦I the tube to the intended use, it is possible to use, in this arrangement, anterior diaphragms 18 of different free internal cross-sections or a fixedly ¦l built-in anterior diaphraglll with a variable free internal cross-section, as I well as to use exchangeable tubes matching these cross-sections.
I The embodilnent of the tube of variable cross-section, according to the invention, shown in Figures 2 and 3 is built up on a baseplate 30. The base-plate is intended for fixing to the screen 17 and has a large central aperture 1 .
~1 ' I .
:~97~36 ' ~ ' I
¦ 3l. Four carrier plates 32, 33, 34 and 35 are located on the baseplate. Each ¦ carrier plate has at least two edges located at right angles to one another, ¦ namely a limiting edge 37, 3~, 39 or 40 and a sliding edge 42, 43, 44 or 45.
¦ The carrier plates are so located relative to one another that the parts of I the limiting edges which adjoin the sliding edges form the frami1lg of a trans-I mission aperture 47 and the ren~aini1lg part of each limiting edge rests againstj ! the sliding edge of an adjacent carrier plate. The carrier plates can be dis-¦placed parallel to the plane of the baseplate by means of a displacement de-Il vice customary for adjustable anterior diaphragms, which device is known to ¦I those skilled in the art and is therefore only indicated with broken lines 50, 51. This displaceme1lt device permits each oF the two pairs of carrier platesJ
formed by mutually opposi-te carrier plates 32, 34 or 33, 35, to be displaced ¦ syn~netrically to the center of the transmission aperture 47, independently of ¦
I¦ the other pair of carrier plates, and in the direction of its sliding edge.
lS ~¦ During this displacement, the two carrier plates of the other pair of carrier 11 plates are carried with the first pair, so that the contact between adjacent j carrier plates and the framing of the transmission aperture always remains I1 preserved. If, for example, the carrier plates 33, 35 are pushed apart, the ¦¦ carrier plate 34 follows the displacement of the carrier plate 33 and the car-rier plate 32 follows the carrier plate 35. In this way, the square trans 1 -~
mission aperture 47 shown in Figure 2 can be reduced and enlarged or be re- ¦
shaped into an upright or horizontal rectangle of any desired dimensions.
! As can be seen most clearly in Figure 2, a side wall 53, 54, 55 or 56 1l projects from each carrier plate. Each side wall is located along the limit-ing edge and one of its lateral edges terminates in the corresponding sliding ¦ edge af the carrier plate. Each side wall stands at right angles to the carrier plate and the four side walls form a closed tube if the four carrier -~
~ i1 li .
~L~97436 ll l ~¦ plates are pushed together sufficiently far that in their limiting edges frame¦
¦ the smallest envisaged transmission aperture. In the lateral extension of each side wall, and above the limiting edge, there is additionally fixed a I thin shaft 60, 61, 62 or 63. On this shaft a plurality of lamellae are pivot-ably mounted, of which, for clarity, only lanlellae 69 to 71 on the shaft 60 of the carrier plate 32 are identified by reference nunlbers. All lamellae can be pivoted between a laid-down position in which they are located virtually l parallel to the surface of the carrier plate, and an erect position, in which ¦I they are located parallel to the side wall. In FIGURES 2 and 3, the lamellae ¦¦ 65 to 68 on the carrier plate 32 (and the corresponding lamellae of the other !
¦I carrier plates~ are drawn in the erect position, and the lanlellae G9, 70 and ¦ r ¦ 71 on the carrier plate 32 (as well as the correspolldillg lamellae of the other carrier plates) are drawn in the laid-down position. As will be immediately I obvious to anyone skilled in the art, it is possible, by erecting those lanle-llae which are located along the parts of -the limiting edges which form the framing of the transmission aperture, to form a tube the internal cross- ¦ r section of which is virtually of the same size ancl the same shape as the cross-section of the transmission aperture. Because the lamellae not requiredl for broadening the tube walls relnain in their laid-down position, the externalj cross-section of the free end of the tube ;s not much larger than its internal cross-section, that is to say, the cross-section of the electron beam which . ¦ emerges through the tube. This construction makes it possible to introduce ¦I the free end of the tube "Yithout hindrance by projecting side pieces, even ¦ into recesses. As has already been described above, this is particularly im-25 ¦ portant when using irradiation equipment in medicinal diagnostics and therapy,¦
for example if the tube is to be brought into an armpit or against the neck ol a pe ent.
. . .
I I , ,_- ;
~L09~436 If the transmission aperture is set -to a dimension which does not corres-~pond to the grid predetermined by the lateral length of the lamellae, the lastl -erect lamella of each side wall projects partially beyond the corner of the tube. This apparent disadvantage is virtually of no importance if the lateral 5` length of the lamellae is not great. I
As can be seen best in Figure 4, each lamella consists of a steel strip 75, at one lengthwise end of which is located a lamella base 76, while in the ,region of its other lengthwise end there are located several absorption pieces ¦1 77, 78 and 79. The lamella base preferably consists of bearing metal and has ¦! a bore 81, by rneans of which the lamella is pushed onto the shaft 60. The absorption pieces are in particular intended to absorb secondary X-rays ancl Il stray electrons. In a combina-tion whicil is particularly suitable for this iI purpose, the absorption pieces 77, 7~ and 79 consist of light metal, steel or~ Antikorrodal.
1 In the embodiment of the new tube shown in the figures, a plurality of ! small permanent magnets is located on eacll carr-ier pla-te, among which, for l! clarity, only magnets 83 to 89 on carrier plate 32 are identified by refer-il ence numbers. These permanent magnets are provided in orde,- to hold the i~ lamellae which have been laid down on the carrier plate.
As may be seen from Figure 2, the lamellae overlap in cross-section. The result of this is that the tube wall cori~posed of adjacently located lamellae I! is "tight" and that none of the erect lamellae can be laid down as long as ¦, the last erect lamella is locked in its position. For this purpose, a thin ¦ tongue 92 is fixed to each carrier plate (Figure 4) which tongue projects, in ¦ the extension of the limiting edge 38, beyond the adjacent carrier plate 32, 1 ;
¦ and carries a stop 90. This stop rests, with one of its sides, against ;the particul r last lamella 66 of a tube wall, and thereby prevents this lamelld ll li , !! l 7~
¦ from being pivoted ~rom the erect p~sition into the laid-down position. pre- I -¦¦ ferably, this stop is wedge-shaped in the direction of the sliding edge. Thismakes it posssible, when displacing a pair of carrier plates in order to i enlarge the cross-section of the framed transmission aperture 47, to slide 1I the stops, fixed to the two displaced carrier pla-tes, with their wedge-¦¦ shaped surfaces under the lamellae 69 of the adjacent carrier plates 32 and to lift these lamellae off the permanent magnets 87.
To each lamella there is allotted a spring 91 which engages in the region ¦ of the base of the lamella (Figure 4) and pivots it into the erect position ¦ as soon as it has been released from the holding magllet.
In the shown embodilllen-t o-f the tube there is furtherlllore located, on the ¦¦ outside of each side wall 54, an electromagnetic switch device 93 which com-prises a lever 94 which has a virtually vertical rest position and can be I pivoted through about 90 into the working position sho~qn with broken lines ~ in Figure 4. After displacing one pair of carrier plates ;n order to reduce ¦I the cross-section of the transmissioll aperture, the switch devices on the side walls of the displaced carrier plates are actuated, whereupon in each cas~
¦ the last lamella of the adjacent tube wall is pivoted into its laid-down j'l position and is held by the corresponding permanent magnet. Because of the ¦¦ mutual overlap of the lamellae, which has already been mentioned above, laying ¦I down one lamella results in all further lamellae automatically being laid down 1 in the direction facing away from the corresponding side wall. This ensures jl that on reducing the cross-section of the transmission aperture all lamellae lii no longer required to form the tube have been laid down on the corresponding ¦ ¦
ijl carrier plate.
I ¦1 As has already been described above, it is necessary, when using irradia- I
1¦ tion equipment for diagnostics and therapy, to briny the free end of the tube t l! .
Il -10-li I
li . ¦
: ` `
~L097~36 ~ `
as close as possible to the object or to the patient. Because of the large weight of the entire installation, special drive motors are used for the re-quired displacement motions or rotary motiolls of individual parts of the equip ment. In order to ensure that these drive motors are switched off as soon as the tube has been brought to a minimum distance from the patient, special ¦ proximity switches are used. In a first embodiment of such a safety device, ¦
I an insulated electrode 100 is fixed to the free end of each side wall. The il electrodes, numbering four in total, are preferably wired electrically in ¦¦ parallel, and form a capacitor with the tube. This capacitor is connected, ¦I in a known manner, to an HF measuring bridge which is put out of balance as ¦I the tube approaches a patient and switches off the feed voltage for the drive¦ motors! via a comparator/trigger circuit, when a presettable unbalance has been reached.
Il In another embodilnent of this safety device, the baseplate of the tube 11 is fixed in an insulated manner to the accelerator casing, and the entire tube ¦l is used as a capacitor electrode.
In yet another embodinlent, the safe-ty device is actuated not on approach-¦
ing, but only on touching, the object to be irradiated. As is shown schematic Il ally in Figure 5, this embodinlent uses a tube insert 102 which is located ¦
¦I parallel to the baseplate 30 and can be inserted into the holding device 21.¦ A stud bolt 103, which passes through a corresponding bore in the baseplate I¦ 30, is fixed to each of the four corners of this tube insert. In addition, ¦1 an electrical switch is provided, of which one contact 104 is fixed by meansI of an insulating disc 105 to the baseplate, while its other contact 106 is ¦ fixed by means of an insulating disc 107 to the free end of the stud bolt.
Around each stud bolt is inserted, between the tube insert 102 and the base-¦ plate 30, a spring lOû which presses the baseplate away frolll the tube insert Il 11 I
1,1 ' . .
Il . .
1' :~' ¦l and presses the contac-t 104 onto the contact 106. The Four switches are preferably ~ired electrically in series. I~hen, on moYing or turnin.g the in-stallation or the patient, the tube is touched and compressed or tipped against the force of one or more springs, the contacts of the corresponding switches I are separated from one another and a safety circuit is broken and switches offi the feed voltage for the drive motors. .
In an embodiment of the new tube used in practice the side length of each ¦ side wall is 4 cm, which makes it possible to telescope the carrier plate suf-II ficiently that the minimum transmission aperture 47 corresponds to a square ¦I with sides 4 cm long. Furthermore, with this embodilllent 16 lamellae are loca-¦
¦¦ ted on each carrier plate, the side length of each lalllella being 1 cm. Accord ingly, the max;lllunl transmission aperture can be set to correspond to a square¦I with sides 20 cm long. As has already been described in detail above, any ¦I quadrangular transmission aperture with dimensions lying between the two stat-! ed extreme values can be set up with the new tube. In ti~is embodinlent, the r il height of the side walls and lamellae is 17 cm.
ii It has already been mentioned that the preliminary diaphragm 18 must be li set to the cross-section of the tube. Since the object to be irradiated de- ¦termines the cross-section of the tube, this tube cross-section is first set 20 up. This setting can be effected manually or by means of servo-motors. Pref-.. : ¦ erably, an adjust~ble anteribr diaphragm is used, and the cross-section of the ¦¦ tube as well as the apertul-e of the preliminary diaphraglll are picked up by li actual value indicators, For example potentiometers. The ac-tual values are~ ¦I then compared in comparators and the resulting error signal is used to con- ¦
~. 25 il trol the diaphragm servo-motors until the actual values for the diaphragm ll aperture corresponds to the actual values of the tube cross-section. It will ¦
be understood that in this way it is also possible to set up a non-linear re--l2-9~3~ I
lation of tube cross-section to diaphragm aperture.
In a further embodilllent of the new tube, an anterior diaphragm 1~, ¦
¦I forming part of the accelerator, is not required. In this embodinlent, the I¦ distance between the baseplate and the carrier plates is increased, and dia-¦ phragm blocks are nlounted on the surfaces, facing the baseplate, oF each car-rier plate, or the carrier plates are constructed as diaphragm blocks. It will be appreciated that with this embodinlent each adjustment of the tube ¦ cross-section simultaneously also results in an adjustment of the effective I¦ diaphragm aperture.
¦¦ Finally, it is also possible to adjust the tube cross-section and the diaphragm aperture by means of remote control from an operating panel or from ¦l a data store. Appropriate circuits are known to all those skilled in the ¦ art and will therefore not be described in detail.
l Though the new tube has been described in relation to an illustrated i embodilllent which possesses four displaceable baseplates and defines a quadran-¦¦ gular transmission aperture, it will be obvious to all those skilled in the ! art that it is also possible to construct a corresponding tube with three or , five or more baseplates which are displaceable symmetrically to one another.
ll Obviously, numerous modifications and variations of the present invention¦
¦l are possible in light of the above teachings. It is therefore to be under-stood that within the scope of the appended claims, the invention may be i practiced othei^wise than as specifically described herein.
. i~
Il ' I
ll -13-1, . I
il
Claims (8)
1. A tube for irradiation equipment for limiting an emergent beam comprising:
a baseplate having a central aperture and adapted to be attached to the irradiation equipment;
four carrier plates located parallel to the baseplate, each carrier plate having a beam limiting edge and a sliding edge located at right angles thereto, the limiting edge of each carrier plate resting against the sliding edge of the adjacent carrier plate and means for displacing each of the two mutually opposite pairs of carrier plates parallel to the direction of its sliding edges and symmetrically to the center of a transmission aperture defined by the limiting edges, so as to continuously vary the transmission aperture and so that during which displacement each of the displaced carrier plates carries with it the carrier plate restinq against the limiting edge of the displaced carrier plate parallel to the direction of the limiting edge of the resting carrier plate;
a side wall and at least one equally high lamella provided on each carrier plate, each side wall projecting at the side of the limiting edge abutting the sliding edge at right angles from the respective carrier plate, each lamella being pivotably fastened in the region of the limiting edge and capable of being laid down on the respective carrier plate or of being erected as an extension of the side wall in order to form a side wall of a tube of variable cross-section, each of the carrier plates, side walls, and lamella being opaque to said radiation.
a baseplate having a central aperture and adapted to be attached to the irradiation equipment;
four carrier plates located parallel to the baseplate, each carrier plate having a beam limiting edge and a sliding edge located at right angles thereto, the limiting edge of each carrier plate resting against the sliding edge of the adjacent carrier plate and means for displacing each of the two mutually opposite pairs of carrier plates parallel to the direction of its sliding edges and symmetrically to the center of a transmission aperture defined by the limiting edges, so as to continuously vary the transmission aperture and so that during which displacement each of the displaced carrier plates carries with it the carrier plate restinq against the limiting edge of the displaced carrier plate parallel to the direction of the limiting edge of the resting carrier plate;
a side wall and at least one equally high lamella provided on each carrier plate, each side wall projecting at the side of the limiting edge abutting the sliding edge at right angles from the respective carrier plate, each lamella being pivotably fastened in the region of the limiting edge and capable of being laid down on the respective carrier plate or of being erected as an extension of the side wall in order to form a side wall of a tube of variable cross-section, each of the carrier plates, side walls, and lamella being opaque to said radiation.
2. The tube recited in Claim 1, wherein each lamella includes:
a steel strip;
a lamella base fixed to one end of the steel strip and having a bore for pushing the lamella onto a shaft; and a plurality of absorption pieces for secondary X-rays and stray electrons fixed in the region of the other end of the steel strip.
a steel strip;
a lamella base fixed to one end of the steel strip and having a bore for pushing the lamella onto a shaft; and a plurality of absorption pieces for secondary X-rays and stray electrons fixed in the region of the other end of the steel strip.
3. The tube recited in Claim 1 including:
a plurality of magnets fixed to each carrier plate for holding the lamel-lae laid down on the carrier plate; and a spring engaging at each lamella base to bring the lamellae when releas-ed by the holding magnets into a vertical position.
a plurality of magnets fixed to each carrier plate for holding the lamel-lae laid down on the carrier plate; and a spring engaging at each lamella base to bring the lamellae when releas-ed by the holding magnets into a vertical position.
4. The tube recited in Claim 1 including:
a tongue fixed to each carrier plate in the extension of the limiting edge and carrying a stop on an end thereof projecting onto the adjacent car-rier plate, one side face of the stop resting against the adjacent erect lamella to prevent the erect lamella from being laid down unintentionally, the other side face of the stop having a wedge-shaped chamfer and being pushed under the next lamella so that when the carrier plate is displaced in order to en-large the transmission aperture, the wedge serves to lift the next lamella off the holding magnet.
a tongue fixed to each carrier plate in the extension of the limiting edge and carrying a stop on an end thereof projecting onto the adjacent car-rier plate, one side face of the stop resting against the adjacent erect lamella to prevent the erect lamella from being laid down unintentionally, the other side face of the stop having a wedge-shaped chamfer and being pushed under the next lamella so that when the carrier plate is displaced in order to en-large the transmission aperture, the wedge serves to lift the next lamella off the holding magnet.
5. The tube recited in Claim 1 including:
an electromagnetic switch device located on each side wall and having a lever for laying down the lamella present on an adjacent carrier plate and adjacent to the side wall onto a carrier plate after a displacement of the carrier plate in order to reduce the transmission aperture.
an electromagnetic switch device located on each side wall and having a lever for laying down the lamella present on an adjacent carrier plate and adjacent to the side wall onto a carrier plate after a displacement of the carrier plate in order to reduce the transmission aperture.
6. The tube recited in Claim 1 including:
an insulated electrode for a capacitive proximity switch fixed to the free end of each side wall and forming with the side wall a capacitor; and means for connecting the capacitor to an HF measuring bridge.
an insulated electrode for a capacitive proximity switch fixed to the free end of each side wall and forming with the side wall a capacitor; and means for connecting the capacitor to an HF measuring bridge.
7. The tube recited in Claim 1, including:
means for fixing the entire tube in an insulated manner to the housing of the irradiation equipment to form a capacitive proximity switch; and means for connecting the tube to an HF measuring bridge.
means for fixing the entire tube in an insulated manner to the housing of the irradiation equipment to form a capacitive proximity switch; and means for connecting the tube to an HF measuring bridge.
8. The tube recited in Claim 1 including:
a plate-shaped tube insert attachable to the casing to form a contact switch;
at least three stud bolts projecting from the insert, the baseplate including bores for the stud bolts to pass through;
a plurality of contacts fixed by insulating discs to the baseplate in the region of the bores;
a plurality of contacts fixed by insulating discs to the free ends of the stud bolts and cooperating with the contacts fixed to the baseplate; and a plurality of springs located between the tube insert and the baseplate for pressing the baseplate away from the tube insert and, in order to close the contact switch, for pressing tile contacts fixed to the baseplate onto the contacts fixed to the stud bolts.
a plate-shaped tube insert attachable to the casing to form a contact switch;
at least three stud bolts projecting from the insert, the baseplate including bores for the stud bolts to pass through;
a plurality of contacts fixed by insulating discs to the baseplate in the region of the bores;
a plurality of contacts fixed by insulating discs to the free ends of the stud bolts and cooperating with the contacts fixed to the baseplate; and a plurality of springs located between the tube insert and the baseplate for pressing the baseplate away from the tube insert and, in order to close the contact switch, for pressing tile contacts fixed to the baseplate onto the contacts fixed to the stud bolts.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH418677A CH614549A5 (en) | 1977-04-04 | 1977-04-04 | Tube for an irradiation device |
| CH4186/77 | 1977-04-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1097436A true CA1097436A (en) | 1981-03-10 |
Family
ID=4271390
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA300,284A Expired CA1097436A (en) | 1977-04-04 | 1978-04-03 | Tube for irradiation equipment |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS53123691A (en) |
| CA (1) | CA1097436A (en) |
| CH (1) | CH614549A5 (en) |
| DE (2) | DE2721043C2 (en) |
| FR (1) | FR2386891A1 (en) |
| GB (1) | GB1597077A (en) |
| NL (1) | NL7803554A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2517573B2 (en) * | 1986-12-24 | 1996-07-24 | キヤノン株式会社 | Information recording device |
| US4952814A (en) * | 1989-06-14 | 1990-08-28 | Varian Associates, Inc. | Translating aperture electron beam current modulator |
| JPH057577A (en) * | 1991-07-02 | 1993-01-19 | Fujitsu Ltd | Radiation image converter |
| US6064720A (en) * | 1997-11-26 | 2000-05-16 | Picker International, Inc. | Magnetic support for removable antiscatter grid |
| DE102012214607A1 (en) | 2012-08-16 | 2014-02-20 | Henkel Ag & Co. Kgaa | Water-soluble packaging with bittering agent I |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA514793A (en) * | 1955-07-19 | T. Green Donald | Beam therapy collimating unit |
-
1977
- 1977-04-04 CH CH418677A patent/CH614549A5/en not_active IP Right Cessation
- 1977-05-10 DE DE19772721043 patent/DE2721043C2/en not_active Expired
- 1977-05-10 DE DE19777714834 patent/DE7714834U1/en not_active Expired
- 1977-07-26 FR FR7722951A patent/FR2386891A1/en active Granted
-
1978
- 1978-04-03 CA CA300,284A patent/CA1097436A/en not_active Expired
- 1978-04-03 GB GB1292878A patent/GB1597077A/en not_active Expired
- 1978-04-03 NL NL7803554A patent/NL7803554A/en not_active Application Discontinuation
- 1978-04-03 JP JP3911178A patent/JPS53123691A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE7714834U1 (en) | 1979-01-18 |
| CH614549A5 (en) | 1979-11-30 |
| JPS6128120B2 (en) | 1986-06-28 |
| DE2721043A1 (en) | 1978-10-12 |
| FR2386891A1 (en) | 1978-11-03 |
| DE2721043C2 (en) | 1986-06-26 |
| GB1597077A (en) | 1981-09-03 |
| JPS53123691A (en) | 1978-10-28 |
| NL7803554A (en) | 1978-10-06 |
| FR2386891B1 (en) | 1980-03-14 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |