US2329318A

US2329318A - X-ray generator

Info

Publication number: US2329318A
Application number: US409934A
Authority: US
Inventors: Zed J Atlee; Howard W Brackney
Original assignee: General Electric X Ray Corp
Current assignee: General Electric X Ray Corp
Priority date: 1941-09-08
Filing date: 1941-09-08
Publication date: 1943-09-14
Anticipated expiration: 1960-09-14
Also published as: GB559004A; FR942895A

Description

Sept. 14, 1943. 2. J. ATLEE ElAL.

X-RAY GENERATOR Filed Sept. 8, 1941 INVENTORQA Zed J 14 5196 {1% Patented Sept. 14, 1943 2,329,313 X-RAY GENERATOR Zed J. At1ee, Elmhurst, andglloward W. Brackncy,

Chicago; 111., assignors to General ElectricX- Ray Corporation, Chicago, 111., a corporation of New York Application September 8, 1941, Serial No. 499,934 I f4 Claims. (01.250429) This invention relates in generaljto electronics and has more particular reference to the'construction of X ray generators, more especially a generator for use in the application of X-rays in body cavities for'therapeutic and other purposes.

An important object is to provide an pX-ray generator"fori'contact andc'avity therapy, and to this end to provide a shock proof generator having facilities for cooling the same whereby to prevent patientdiscomfort when under treatment in contact with the generator.

Another importaht'object islto provide a generator of the character mentioned having a generating. anode formed for insertion as in a body cavity includingImeans to jacket the anode for heat dissipation without materially reducing effective X-rays emitted by said anode when the generator is in operation; aiurther object being to utilize-jacketing *meanshaving a window at the Y-ray emittingcrpo'rtion of thea'node'and formed of material substantiallytransparent to X-raysp'a stillfurther object'being to form the jacket window of beryllium. i V

1 A still further object is to form the jacket as a tube of'suitable material surrounding the pro jecting anode and having a beryllium disc securedin fluidtightr fashion at the end of the tube adjacent to the X-rayemitting end of the anode; Another important object is to utilize a pair of concentric tubes around the :projecting anode whereby to accomplish *jacketing by flowv and counterflowsof a suitable cooling'fiuid through the concentric anode jacketing' tubes. 1 1- Another important object isto'fo'rm the-gprojecting anode-as a tube of metallicmaterial' such as copper having-an anodevtarget fitted at the projecting encloi the tube; a further objectbeing toutilizegold es atarget material; a-still further object being to utilize as a target a plate of gold, orother suitable material, made just thick enough to stop arsubstantial percentage of primary electronsfto thereby maintain X-ray ab-' so-rption at a minimum; yet another object being to support the target plate upon a beryllium disc sealed in the end of the tube and carrying the target material plated thereon to the-desired thicknessof the order of 0.00004 inchor 2.0 microns, which. is the thicknessl of gold capable of stopping 90% of the electron beam applied on the target at 70 kvrpJ o Another important object is to form the anode as a metal tube preferably comprising copper having a monel bushing silver solderedat' the end of the tube and upon which bushing is secured a window. disczof beryllium brazed to the bushing pr ferablywvith copper silver soldered 'andhav ing a thin'gold plated film upon the inner surface of the window disc. I

Another important object of the invention is to provide an improved electrode conf guration and relationship, and more particularly to immerse the cathode in the anode whereby to ensure that the electron source at the cathode and'the entire electronbeam between the source andthe anode target are completely shielded from the-intense o electrid'charges that collectupon the walls of the generator envelope during operation, thereby eliminating completely the biasing effect that would otherwise be imposed bysaid' wall charges on the electron beam and result in fldeflection thereof. I I p Another important object resides'in providing a generator comprising a tubular projecting anode mounted in a collar or flange forming a support frame, the flange carrying an annular rim extending on the side'of the flange opposite from the tube and supporting, a preferably glass envelope having a glass-to-metal seal with said rim, the glass envelopeserving to supportthe cathode structure therein in alignment with the anode tube and said flange carryinga sleeve-likeshield in concentric alignment with the anode tube,;the cathode being supported in 7 position with its electron emitting element immersed withinvthe shield j v Another important object is to provide a shock proof supporting casing forthe generator including facilities for jacketing the projecting anode for the circulation of a cooling fluid such as i water thereabtout; a further object beingfto ing for a generator of the character mentioned wherein the casing comprises cooperating parts including a preferablytubular portion forming a container in which the generator maybe insulated as by immersion in oil and' anexternal' housing adapted to enclose the casingand generator including the projecting anode portion of the generator, the external housing carrying facilities for cooling the projecting anode portion of the generator and for focusing the electron beam therein when the generator is in operation; a further object being .to form the inner casing as a cylindrical tube affording a mounting at one end for the generator and a mounting at the other end of the casing for a bushing containing electrical connections for powering the mounted generator from an external source of electrical energy.

Another important object resides in providing means to compensate for the expansion and contraction of insulating oil within the inner casing; a further object being to utilize expansion means preferably comprising synthetic rubber forming a bellows within the insulating chamber.

Among the numerous other important objects of the invention is to provide a safe X-ray genorator for contact and cavity thereapy; a generator of simplified design having an improved anode structure in combination with an immersed cathode thereby improving the operating characteristics of the device more particu' larly with respect to uniformity of electron flow; a device of the character mentioned having a shock proof casing in which all high voltage parts are oil immersed and thus safely insulated, the casing including novel means to compensate for expansion and contractions of the insulating oil therein; a device in. which the anode structure is jacketed for cooling the same without impairing X-ray emitting efficiency, ,and' wherein, more particularly the anode and its cooling jacket is sized for insertion easily as in a body. cavity to thereby facilitate X-ray treatment of body tissues in direct contact with the X-ray generating source.

The foregoing and numerous other important objects, advantages and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in .connectionwith the accompanying drawing, discloses a preferred embodiment of the invention.

Referring to the drawing:

Figure 1 is a, sectional view taken longitudinally through an X-ray generator and casing embodying the present invention;

Figure 2.isa sectional viewqalong the line 22 of the .X-raygenerator shown in Figure ,1; and

Figure 3 is' a'sectional view taken substantially along the line 3-3 in Figure 1. e

To illustrate the invention the drawing shows an X-ray' generator ll comprising an anode .l3,

acathode 1.5 and enveloper'neans Ii enclosing the anode and cathode.

The anode I3 preferably comprisesla disc [9 of material, such as beryllium, which is .s'ubstan'- tially transparent to X-rays. The. disc is sealed in the end of a preferably-copper tube 2| which forms a part of the hermetic envelope The beryllium disc l9 may be secured at the end of the tube 2| by brazing it with preferably -50 copper silver solder to a bushing 23 preferably made of monel metal, which is secured as bysilver solder in the end of the tube 2L It will be understood that X-rays generated at thedisc 19 by electronic impact thereon will be projected through the disc and outwardly of a body cavity in order to allow treatment of tissues within the cavity. In order to develop,

X-rays at the disc l9 it is necessary to provide a suitable target for the reception of electrons and capable of developing X-rays in response to electron impingement thereon. To this end the target may comprise any suitable target material but we prefer to employ gold for the purpose. Consequently, the. surface of the disc I9 facing into the tube 2i carries a layer of gold 25 thereon for the purpose of providing an anode target. The gold forming thetarget 25 is preferably applied on the beryllium disc l9 by electroplating the gold thereon to a thickness of the order of 2.0 microns or 0.00004 inch, which is thethickness of gold capable of stopping substantially all electrons impinging X rays substantially all of which may. escape outwardly through the disc l9.

The end of the tube 2| opposite from the end in which the disc 19 is fitted, is sealed in an opening .21 formed through a plate 29 which forms a part of the envelope l1 and which provides a means formounting the.

generator in operating position.

The generator envelope H, in addition tozthe tube .21 and plate 29, comprises a preferably cylindrical portion 3| which may conveniently comprise glass, the portion '2l being sealed ,at one end by means of an annular glass-to-metal seal 33 upon the rim of a metallic sealing'member 35 which has an inwardly flanged portion sealed asat 31 upon an annular seat formed in The cathode structureylS comprises a head 45 formed with a socket" in alignment and facing toward the plate mounted end of the tube 2|.

An electron emittingelement',preferably a filament 49, is supported on the'headfl adjacent the bottom of the socket :41. The'headli is supported as'iby. the intermediate frames 5| and 53 on a stem 55 which projects through and which is sealedin a central opening formed in the bottom of the cup shaped end seal member 43. The head 45 and the support members 5| and 53 are hollow to accommodate electrical conductors 51 which are connected with the filament 49 and which extend thence'through the head and the hollow sup ort members and through seals formed in the-bottom of the seal member 43; The, member 5| may also carry a cylindrical skirt 59 which surrounds and en closes the support member 53, the seal member 43 and theglass-to-metal seal 4| for the purpose of shielding the seal M from impingement by stray electrons. The skirt 59 also ,defines a chamber in which may be disposed gettering means 6| illustrated as a hollow metallic wire containing a 'gettering medium such as barium, one end of the wire being grounded as on the frame member'53and the other endbeing connected to a conductor 63 which extends through a sealin the member 43.

In conditioning an X-ray generator for operation, it is necessary to remove all gas present within the envelope, and also any gas occluded inthe electrodes and in the material of the envelope itself. If such occluded gases are not substantially entirely removed, they will gradually be released withinthe envelope and impair thereon thereby providing for the efiicient generation of.

the exhausted condition at whichthe .devlceris designed to operate. Removal of gases from the envelope is accomplished by baking or otherwise heat treating the entire device at/atem'perature short of the softening point'of the glass, while maintaining the envelope in connection witha; suitable exhaust pump, and by heating the electrodes to a high temperature, either by'electron bombardment or by placing the electrodes in a magnetic field fluctuating at frequencies .at the order of radio frequency After all gas including occluded gases and other impurities have thus been removed from the envelope; the exhaust connection may be sealed oil, as at '65, and as -a-final step the get-' tering material may be volatilized within the en'- velopein order to form gettering end'products in which any trace of gas or other impurities are combined with the gettering material to form inert and innocuous material which remainswithin the envelope' during 'the service life of the device in the form of a film-like deposit upon the ;inner surfaces of the" skirt 59" upon which the gettering end products condenseas a result of thegettering operation? I The gettering material, which is preferably barium and/or 'magnesium-'contained in the hollow wire 6| maybe volatilized by applying electrical potential between the conductor- 63 and the stem 55 thereby heati 'igfthe wire M and vaporizing the I gettering'i materialcontained therein, the wirehaving aweak'en'edwall-poring 'the :electron streamLIrom the electrostatic effects ofenvelope wall charges.

" ZIt will beseen'from the foregoing that our in;

ventionicontemplatesitheprovision of an X-i-ay generator having 'an anode target vforming an X-ray source; arrangedin a fashion tope'rmit the same to'b e inserted asiini:a"'body cavity for the treatment of the tissues of th'ecavity; andvit will be seen that the arrangementof the anode Y target at the end of. the relatively, slender elongated tube 2|, which may be anywhere from 6 to 18:inchesin length, laflords a convenienttreat ment'of body cavitytissuesu It 'should'be understood, however. thatthe operation of an X-raygenerator is accompanied tion longitudinally thereof through which w'eali v ened wall portion 'the'vaporizedfgettering'jmaterial may be expelled into the chamber enclosed by the skirt 59. I y I I It should be understood that anX-ray generator functions to produce X-rays at the target 25 by the impingement thereon of electrons-gen eratedand emitted at the cathodeelenient dil and directed as a stream eupjon 'the target' under the influence of electricalpotential applied between the cathode'fllament andthe' anode target. The cathode is energized'for electronernission by the application-of filament energizing poten tial between the 'conducto'rsi'l. j I

' Although the operating potentialv appli'eclTb e'a tween cathode filament and anode'target' 'serves to direct the electrons in a stream focused upon the target, various disturbances i may cause some: of thenelectrons to escape from the stream "and become stray electrons within the" envelope, which stray electrons impinging on the envelope by the generation of appreciable quantities of heatparticularly where the generator is designed forhighgtension operation. We contemplateapplication of our present invention in high voltage generators adapted to operate at voltages of the 0rder-of;; 70.;-kv.' p. and; our invention embraces means not only for-rendering the device shock proof but also forcooling the anode structure to enable the device to belused for therapeutic purposes in body cavities withoutwcausing undue pa tienttdiscomfort'. To. this end we provide casing means serving not only to render the device. shock proof but alsov to cool the anode structure. e

, ,The casing means comprisesapreferably cylindrical shell II for. receiving the generator, the

shell preferably comprising relativelyfthinsheet metal stockandhaving amounting ring 13 sealingly secured, at oflelend of the shell II in posi:

tion to form anannular support for the marginal edge of the generator mountingplat'e 29. The

plate 29 may be secured on the mounting ring as by means of. the' f astening; screws'lfi to support the" generator with itsanode structure projecting walls and particularly upon the glass po-rtionsiof 1 the envelope may build up charges having de leterious effects upon the generator; Such charges may etch andweakenthe walls 'andmay puncture the envelope particularly. at; the end seals 33 and 4|; Furthermore, when operated at high voltage, the charges built up on the walls as a result of stray electron impingementmay exert electrostatic effects upon the electron stream-and cause it to deviate from'the deslredflowpathbetween the cathode and' the target25. In order to minimize the'effects oi strayelectronswe i'ni-f.

outwardly o he p anin; l ia on? d h r the J cathode end of y the generator including theenvelopeportion 3| andjthe seal member' being enclosed within the shell-ll, and the mounting plate 29 forming a sealed closureat the end of the shell H. The other end of the she'llllhas a mounting ring ll sealed thereto in position'to form supportgfor a cable bushing lfli 'which may be secured in place 'by means of a clamp ring I 8| and fastening screws 83 to receive a standard cable plug 85. The bushing 19, of course, may be provided with contact means 81 adapted to form electrical fconne'ction with the conductors '51 which are suitably anchored Ona t'erminalblock 89 carried the stem outward of the generator in-position-to engage the bushing contacts 81.

The shell 1 l'forms a charn'ber'Ql within which the generator is enclosed preferablyin position immersed in a'suitable insulating 'mediumsuch as oil. I'he chamber 9| around the generator may be charged with .oil through a filling opening defined by a bushing 93 which is normally sealed as by means of a closure-plug 95; -In order to accommodate for expansion and contraction of the insulating oil within the chamber 9l-we provide compressible means}?! in the form of an inflation device within the chamber.-.7Thisinflation device comprises, in the illustrated embodiment, a hollow annular expansionelement filled ,Witha. suitable gas under slight pressure, the inflation device being adapted to expandunderthe influence of the gas therein and accommodate any contraction of the insulating oil within the chamber 9h "The inflation device I941 preferably comprises an annular membenof rub- :ber-like material such as neoprene,- or other e t lez l st c eete elsvrbiqe; emanate electronsrinxthe envelopebut also aids in guarda'ndzn'ot rsubject to deterioration inf contact with oil. Theannular member 91 ispreferablyas sembled in the shellliiin positionembraclng the generator and may be conveniently-anchored by forming the member: '91 with an annular groove 99 at one end imposition tor: receive 'an'annular flange I8 I formed on the mounting ring I3.

The device is 'r'ender'ed: substantially shockproof byzg'rounding the shell 'II and the anode structure of the generator mounted thereon and by applying the high-operating potentials to the generator :through the shock proof insulated structure comprising the plug 1 device"85* and the bushing I9 on the high tensionconductors'.

" For the purpose of cooling the anodestructure,

we provide "jacketing means I03 surrounding the anodetube-2|, together Withfacilities for circul'a tildg a Cooling fluid T through "the" jacketing means and around the anode. The jacketing means comprises apair of concentric tubes IiIS andWllI interconnected by spacing means Hill which also carries a beryllium and closure disc I u atone e'ndof, the tubular jacket structurel'The tubes I05 and IiI'I at the other endof" the jacket structure are secured in a support "collar: -II'3 which in turn may be anchoredon the generator mounting plate 29 as'by means of scretvs '-'II5.

The support collar II3 also carries an inlet pipe I I 1 and an outlet pipe I ISffor' the ci'rculationlof a cooling "fluid," preferably Water, to andfif'ornfthe jacket structure; I03. To thisend the inlet ipipe III is'connected through the outer jacket tube I05 and into theinner tube I01 'to'deliver the cooling fluid within the innentube and directly upon the outer surfaces of the" anode tube "2!, near the plate. anchored end of, said anode tube. The coolin fluid may now thence toward and around the target end of the tube M and pass thence between the inner tube I01 and the outer tube I05 to the outlet pipe I. I B Which is fitted into the outer tube adjacent the mountingIplate 29. The pipes II! and H9 extend radially from, the jacket structure to the marginal edge of the I mounting plate 29 and thence extend longitiidinally of the shell 'II to the remote end thereof where they maybe fitted with means for connec- .tion to suitable apparatus forcirculating the V coolingfluid.

- For the, purpose of focusing the-electron stream upon a localized'area of the target we-mount an annular magnet I2'I in position encircling the anode tube ZI near the end thereofwhiohis secured on the plate 29. 'Ihisfocusing magnet I2l may comprise merely an annular ring of magnetic material forminga permanent'magnet ormay take, the form of an electromagnet com prisin'gcooperating members I23 and Informing an annular shell'containing a winding I21 adapted to' be energized through conductors I29.

I The focusing magnet 'IZI has ac'entral opening through which the'anode tube 2| and the jacketing shells Ill5 and IO'I extend so that the magnet may be mounted against thepip'e carrying collar I I3; and the magnetmaybe enclosed inmounted position by an outer casing l 3i having cylindrical walls 133' enclosing the casing II and the-pipes ill and -II9,' and a p0rti0nI35 enclosing the magnet I2I and formed with an opening through which the j'acketing meansI I13 and the anode tube 21 extends; The casing I3Iat its end remote from the magnet'enclosing portion I maybe secured to the casing H by suitable fastening devices. v e i It will be seenthat the'device of our present invention is of simplified construction affordin convenient means forcontact and cavity therapy;

that the several 'partsmay bereadily torn down for repair or repl'acementfthat all parts are" thoroughly insulated to. thereby afford maximum protection against electrical shock; that'effective means is provided for adequately cooling the anode to permit'the application thereof in contact with body tissues without discomfort; and that the device aifords a convenient means fo'rthe accomplishment of X-ray therapy. I

It is thought that the invention and its numerous attendantadvantageswill be clearly under-I,

stood from, the foregoing description; and it is obvious that numerous changes may be'm'ade in theform, constructionandarrangement of the several parts without departing from the spirit and scope of the invention, and without sacrificing its attendant advantages, the form herein dis closed'being inerely'for the purpose'of demonstrating the inventionL I The inventionis hereby claimed 1. An X-ray generator comprising a cathode; an anode, an envelope enclosing the anode and cathode, saidenvelope comprising a'metaltube having an end facing said cathode, said anode being supported at the other end of the tube and comprising a plate of material substantially transparent to X-rays closing'the end of the tube and carrying a layer of target -material' thereon whereby X-rays' generated at said layer may be projected throughsaidi" plate and out Wardly of the end of the tube in a direction axially thereof. jacketingmeansenclosing said tube including the plate carryingend thereof for the circulation of cooling fluid around said tube and anode, said jacketing means comprising a pair of concentricsleeves disposed about said tube and affordin-g, therewith,a channel for circu-" lating acooling fluid from an inlet near the cathode facing end of the tube to its plate carrying end, and a concentric channel for returning said I fluid from the plate 1 carrying .end of the t wardly of the end of the tube in a direction axial ly thereof; jacketing means enclosing said tube including the plate carrying end thereof for the circulation of cooling fluid around said tube and anode, said jacketing means comprising a pair of concentric sleeves disposed about said tube, and affording, therewith, a channel for circulating a cooling fluid from an inlet near the cathode facing end ofv the tube to it plate carrying end, and a concentric channel for returning I said fluid from the plate carrying end of the tube to an outlet near its cathode facing end;

including afrarne on the plate carrying end of thetube, said frame forming seats for receiving the ends of the sleeves to maintain concentric spaced relationship of the sleeves and tube.

'3. X-ray generator comprising a cathode, an anode, an envelope enclosing the anode and cathode, said envelope comprising a metal tube having an end facing said cathod said anode being supported at theIother' end of the tube and-compris'ing-a plate of material'substantially as follows I I I the end of the the end of the tube in a direction axially thereof, jacketing means enclosing said tube including the plate carrying end thereof for the circu-' I lation of cooling fluid around said tube and anode, said ja-cketing means comprising a pair of concentric sleeves disposed about said tube and affording, therewith, a channel for circulating a cooling fluid from an inletnear the cathode facing end of the tube to its plate carrying end, and a concentric channel for returning said fluid from the plate carrying end'of the tube to an outlet near its cathode facing end, including a frame on the plate carrying end of the tube, said frame forming seats for receiving the ends'of the sleeves to maintain concentric spaced relationship of the sleeves and tube, said frame being formed with ducts interconnecting said concentric channels at said frame, said frame carrying. means forming a cover enclosing said plate.

4. An X-ray generator comprising a cathode, an anode, an envelope enclosing the anode and cathode, said envelope comprising a metal tube having an end facing said cathode, said anode being supported at the other end of the tube and comprising a plate of material substantially transparent to X-rays closing the end of the tube and carrying a layer of target material thereon whereby X-rays generated at said layer maybe projected through said plate and outwardly of the end of the tube in a direction axially thereof, jacketing means enclosing said tube including the plate carrying end thereof for e the circulation of cooling fluid around said tube and anode, said jacketing means comprising a pair of concentric sleeves disposed about said tube and affording, therewith, a channel for circulating awcooling fluid from an inlet near the cathode facing end of the tube to its plate carry ing end, anda concentric channel for returning a said fluid from the plate carrying end of the tube to an outlet near its cathode facing end,ineluding a frame on the plate carrying end of the tube, said frame forming seats for receiving the ends of the sleeves to maintain concentric spaced relationship of the sleeves and tube, said frame being formed with ducts interconnecting said concentric channels at said frame, saidframe carrying means forming a cover enclosing said plate and; said cover comprising material substantially transparent to X-rays.

ZED J. ATLEE. HOWARD W. BRACKNEY