US1617267A - X-ray apparatus - Google Patents

Description

Feb. 1927. l 617 67 M. monmsou X-RAY APPARATUS Filed April 21. 1923 2 Sheets-Sheet 1 d I I mvsmqn Feb. 8, 1927. ,267

M. MORRISON I X-RAI AYPARA'I'US Filed April 1'. 1923 2 Sheets-Sheet 2 Patented Feb. 8, 1927.

UNIT En s1" MONTFORD MORRISON,

OF CHICAGO, ILLINOIS.

x -RAY APPARATUS.

Application filed April 21, 1923. Serial No. 633,712.

The present invention comprises a new apparatus for holding X-ray tubes particularly when they are in operation.

Some of the objects of my invention are, first; to provide an improved means for holding X-ray tubes particularly while in operation, second; to proviglg an i mppov ed means for in operatiop third; to provide an improved means for stabilizing the tube operation, fourth; to provide improved electrical protectionfor animal life from the high voltage circuit, fifth; to provide adequate X-ray protection for animal tissue not intended to be exposed to the X rays, sixth; to provide improved voltage protection for the X-ray tube, seventh; to provide a substantially coronaless electric circuit in accordance with my application Serial No. 460,835, filed April 21, 1921, on rectifiers for electric current.

As a means for holding X-ray tubes while in operation, in theprior art they have been clasped along their glass stems by materials of different specific inductive capacity than the medium surrounding the glass tube, and since the said glass stems contain electrodes which have a high potential difference above ground impressed upon them, there results a concentration or distortion of the electric field within and about the glass tube in a neighborhood of not only these clasps but in the neighborhood of all other materials incorrectly disposed, I have discovered.

In the prior art these ,clasps and other materials incorrectly disposed prevent not only the proper cooling of the glass due to their deflecting the cooling medium from its proper course but also said clasps prevent the glass from expanding and contracting in accordance with its natural inclination, thus causing fractures and other damage, I have discovered.

The use of clasps and improperly shaped objects disposed in the neighborhood of the glass tube, in distorting the field within-and about the X-ray tube, tend to cause or exaggerate erratic behavior in the operation of the said tube, I have discovered.

In the prior art the high tension electrical circuits of such X-ray apparatus as herein disclosed, have not been adequately protected by ground shields or sufiiciently remotely disposed to avoid danger from electrical shock, I find.

The use of X-ray-opaque shields, of forms different from those which are symmetrical about the axis or axes of the electrodes, are ineifective and inefficient with respect to their apparent value, judged from their thickness and material, I find.

X-ray tubes operated at very high voltages are very sensitive and liable to rupture by voltages above those for which the tube is constructed; and due to surges, traveling waves and the like, I find that voltage protective devices remotely disposed from the tube are inefficient and inadaquate.

X-ray tubes operated at very high voltages, particularly those which are operated for long periods of time, are placed in holders, containers and, or circuits, which due to the formation of corona give out great volumes of nitrous acid and ozone, which are very nauseating to animal life and very active chemically, which results in not only the production of sickness but also in the destruction of property.

It is, among other things, with the above mentioned disadvantages of prior art in mind that I have made the invention and discovery set forth in this disclosure, and among the objects of my invention are the substantial reduction in those disadvantages above set forth in the prior art and an improved X-ray apparatus as a whole.

In the accompanying drawings, Fig. 1, is an illustrative sketch of one form of my invention as'yiewed in its side elevation in part section, and Fig. 2 is a section taken through a right plane at a b in Fig. 1, Figs.

3 and 4 are cross-section details of the tube terminal socketsin Fig. 1, and Figs.5 and 6 are respectively endand side views of a table which I may use in the therapeutic application of my invention.

Referring to Figs. 1 and 2, the form of my invention illustrated therein consists of means 1 for supporting the tube holder ,2 and in the form shown, the part 2 consists physicallymofahollomcylinder having one or more openings 3 for the emission of X-. rays, and one Quanta. neaiaasieatari Possible ntakemeranataat at. a g

medium causedutoflow,by means ofadevice Well as affording a cushioning effect for the {i The hollow cylinder 2 is provided with longitudinal expansion and contraction of end shields 6 and 7, which close or nearly the X-ray tube. close the otherwise open ends of said hollow It will be appreciated by those skilled i cylinder. the art to which my invention appertains i Alternating current source 33 feeds curupon reference to Fig. 1, that I may use a rent to step up transformer 34 and the ciraperture,,anl;raystranslucent material cuit of which current may be supplied. with filter and make my apparatus otherwise liq a switch 35, said step up transformer is con- 11i( ti ht: except at such places as where I nected up to preferably a rectifier 36 and to might desire the liqu igl tp esca 3e thereby high voltage conductors 87 as disclosed in utilizing a ligaid cgplin 1d ating my patent application, Serial Number 160; 835, filed April 12, 1921.

In the case of the use of a hot cathode X- ray tube, alternating current generator 83 ,catamaran.usearlerisesubstanti y as illustrated, and utilize all or other gases as msulatlngand cool ng mednuns.

Aittiit ioii i s directed to the fact at this 8 or other means may supply regulator 38 and point that X-ray tubes and the like, oper- X-ray, tube filament heating transformer ated in holders of the prior art, which have 39, heating current for the filament of the clasps about the stems, and other materials X-ray tube 16, as is well understood in the in the near vicinity of the glass envelope, art. have the inner walls of the said glass en- The high voltage electric current is led velope more or less non-uniformly deposited into and out of said hollow cylinder by with metallic vapor and the like, which dismeans of terminals 8 and 9 which have contort the electrostatic field within and about vent-ional insulators 10 and 11. Ter1ninal"-tl1e said X-ray tube, causing more or less parts 8 and 9 are electrically connected to ierratic or exaggerated misbehavior in the spheres or other surfaces of large curvature operation of the said tube, and sometimes 12 and 13, which in turn are connected to rupture and other disastrous results. terminals 14 and 15 of X-ray tube 16, thus Referring again to Fig. 1, it will be apforming the electric circuit from terminal 9, preciated that electrically an X-ray tube is O for instance, to surface13, thence through substantially a small electrical conductor the tube to surface 12, and then to terminal formed by electrode 22, electron emission 8, and through Whatever high voltage or stream 23 and anode 24, and if I choose to combination of voltage circuits that may be operate my apparatus with a aseous coolrequired or used externally with my invening medium, and uit'iiss tion. been operated i ii a prior art tube-holder, the 100 Fig. 3 is a cross section of the surface-figeffect of the glass envelope around the tube ure 13, and consists of a general surface as would not, because of the substantial idendisclosed in my before-mentioned patent tity of the specific inductive capacity of the application of any form Whatever, and into space within the tube and without the tube, one side of-Which figure is a socket or rehave any material influence upon the dis- 105 ceptacle-17, for receiving and-holding-one tribution of the electrostatic field within of the Xray tube'terminals, and comprises the tube, in the absence of substantial gas means 18, 19 and the like for supplying one ionization within the tube. or more insulated electrical conductors as So that in order to operate a tube under that X-ray tube terminal which it receives its most favorable conditions the electroand holds may require. static field within the tube and about it Fig. 1 is a cross section of the surfaceshould be as uniformly distributed as posfigure 12, and I have illustrated a form of sible, and in the case of a tube having electube socket or receptacle which may be comtrodes lying in the same straight line, such bined With or used separately with the conas X-ray tube 16 illustrated in Fig. l l eagj m ll struction illustrated in Fig. 3, and which inview of thecon ditions set socket or receptacle provideslongitudinal foregoing, produce a very uniform field adjustment and compensation for longituaround the tube by surrounding the eleg; dinal positioning and longitudinal varia- 9 5 tions of the tube, as well as automatic means thus in effect estabhsl for allowing for the longitudinal expansion Satstaatiailvfttatif and contraction of the tube during heating cylindersw 10h a ,1 and cooling, and without imparting unnecana pn sil essary mechanical strains upon the tube. fora Fig. it comprises a surface of any general Ho *ever, let it be understood that in disform as aforementioned for Fig. 3, and a closing my invention it is only incidental receptacle 20,Y-which has adjustment longithat a concentric cylinder is illustrated be tudinal With the tube and means, such as the cause of the fact that the X-ray tube ilspring or elastic device 21, for taking up the lustrated herein has its terminals in one 65 slack out of the longitudinal adjustment as straight line, but in reality my invention A ,anasincr acu Z 0-111 sen eatherein. O

calls for a substantially more uniform field about the tube than heretofore used, and if some other form of tube be employed, the form of my electrostatic shield will change in accordance with the physical figure, dimensions and directions of the electrodes such as to produce a more uniform field than heretofore employed.

It will be appreciated that the absence of imped ments around and about the X-ray tube 16, cooling medium of whatever form it maybe and in whatever direction or directions it may flow, will produce more effective cooling by unimpaired contact with, flow by, or to and from the walls of the X- 'ay tube envelope, the terminals and whatever means or devices are supplied w'th or form a part of the tube terminals or elec trodes, to effect or improve the cooling of the target and other parts of the tube.

lVith the form of my invention illustrated herein, I @lllllQllfiLllQllQliQ i I t1 I whichrcaiises the flow of air or other gases about the terminal or cooling surface 12, around the stems and spherical surface of the X-ray tube, thence around the surface 13, and thence substantially uniformly through the opening 1, or the flow considered vice versa.

It is not fundamental to my invention to have the cooling medium flow in any particular direction, or to have it taken in or exhausted at any particular place or places, but to have it flow freely about the envelope and, or the terminals of the tube.

However, I consider as a preferable blower, one blowing in* the longitudinal d rection of the tube, and as illustrated on the anode terminal or cooling surface and substantially uniformly around the tube; thence in a direction longitudinal with the tube, and finally through an opening which is substantially symmetr' cal as a figure of revolution taken about the axis of the tube. It willbe appreciated that the cooling medium for ed in by means 0 nst tihe cotiling surface 12 is the whole cylinder 2 and does not necessarily have its whole heat contained or carried along in the immediate neighborhood of the walls of -the glassenvelope of the X-ray tube.

I have spoken largely of glass tubeabut of course my fnvention is applicable toany form of X-ray or vacuum tube envelope 5 ,5,which' as a ivhole or as a part;possesses the iiiedequate su ati lilllllslc wllfi 1 1v 10 the const ctio n o e tube.

I have found that by surrounding an X- m ray tube with anelectrostatic shield ofsuch a form as to give a substantial uniform electric field around the tube, there is a decided stabilizing act'on in this construction over and above what would be experienced by clasping the tube about its stems, or having other improperly designed or shaped objects 'shielcL glhat the said in the near vicinity of the tube during operation.

I have found that an X-ray tube operated in a holder of the design employed in the prior art may become erratic and uncertain in its behavior and operation, and the same said tube when placed within electrostatic shieldof the kind which I have invented, becomes more stable, moreccrtain in its operation and gives a longer l'fe to the tube, which is an important factor in consideration of the present high cost of X-ray tubes, and in particular where they are used for almost continuous service in the therapeutic destruction of cancerous tissue and the like, on human beings. This stabilizing action also provides a more satisfactory and efiicient treatment due to the lack of interruption, variations in the treatment and the like.

' In the disclosure of my invention let it be understood that I have not invented solely an improved devicefor the therapeut c use of X-ray tubes, as it will be appreciated by those familiar with the art to which my invention appertains, that my apparatus is suitable for any and all uses to which high voltage X-ray or vacuum tubes are or may be put.

Referring back to Figs. 1 and 2, it wI-ll be observed that only the tops or corona guards of terminals 8 and 9 are dangerous electrical conductors, and that nowhere else are electrical conductors exposed or accessible to human touch, and in my invention I so disposed these terminals as to make them inaccessible to physicists, operators or pa-. tients by remotely disposing them in such at manner as to render them harmless. El ec trostatic shield 2 and electrostatic gga rds 25% 1 and 26 maybe all grounded or operated at, substantially ground potential-, thus elimri nating elegtrrc al danger. W i M It will be appreciated, in the absence o f direct metallic grounc mg; of electrostatic shield will assume some potential between that of the tube terminals 12 and 13 depending upon the electrostatic capacity between the said terminals 12 and 13 and the shield 2. since the terminal 12 forms with electrostatic shield 2 an electrostatic condenser and shield 2 with terminal 13 likewise forms another electrostatic condenser. The potential of shield'2 in the absence of the said ground being at the center plate of two condensers in series, assumes a potential between that of the two said terminals and the potential of said shield 2 will, therefore, depend upon the relative capacities of the two condensers in series together with some influence caused by the wave-form ofthe impressed electro-motive force and leakage of the circuit.

In the use of substantially X-ray-opaque materials for the protection of workers,

manna Tit operators and patients, against burning of X-rays where the burning is not desired, the effectiveness of the X-ray protection with reference to the weight of the material may be improved by having the X-rays fall upon this X-ray opaque material at such an angle as would make this angle more constant than has been heretofore employed by the prior art. That is to say, if one thickness of material is used over any considerable range of surface, the more uniform the extent of the angle of the X-rays over this surface, the more efiicient is the X-ray opaque material with reference to its total weight. Thus by employing a means for accomplishing this I have improved the X-ray protective device of the prior art. The ends of my devices such as at the opening 4:, are so baflicd as to prevent the escapcment of X- rays at any such point.

Electrostatic shields, 25 and 26, are of such a form and thickness andhave such apertures so disposed as to prevent the escape of any X-rays which originate in the neighborhood of the focal spot from passing through the insulating materials and thence through the openings through which the insulating materials protrude. In some cases I make terminals 10 and 11 with concentric substantially X-ray-opaque-material sheets, of such forms as are commonly employed in the so-called condenser terminals, which further prevent the escape of any X-raythrough the apertures of the corona guard 25 and 26.

On all extremely high voltage circuits, surges, traveling waves and the like are apt to produce voltages at one part of the high voltage circuit different from that of another part, and voltage protective devices remotely disposed from the tube terminals do not always give adequate voltage protection, in view of which I have associated an adjustable parallel spark-over gap, 27, very closely with the tube terminal, thereby improving the voltage protection of the tube over the prior art, by having a substantial, definite safety gap closely associated with the terminals of the X-ray tube.

All those familiar with the protracted use of very high voltage X-ray tubes as well as those familiar with the operation of very high voltage apparatus, appreciate the extreme disadvantage of the continuous generation of large quantities of ozone and nitrous acid by the high voltage conductors in other parts of the circuit.

Following the invention disclosed with my before mentioned patent application I have provided the same means in this invention for substantially reducing this corona and nitrous acid. It will be appreciated, particularly by those familiar with the artof X-ray therapy, that patents become extremely nauseated, sometimes unbearably so, by the production of the aforesaid ozone, and

nitrous acid, and that in many installations it has been necessary to construct an elaborate means for exhausting the air rapidly from the room in which the X-ray tube is operated, or provide elaborate systems for removing the ozone and nitrous acid from about, and from the neighborhood of, the

X-ray tube. Both ozone and nitrous acid are very active chemically and react chemically not only upon the delicate parts of the human anatomy but upon the metals and furnishings in the room sufficiently so as to impair their use and value.

I have discovered that if the corona guard 2, surfaces 12 and 13, terminals 8 and 9, and other electrical parts are of such proper design and proportions substantially as set forth in my before mentioned patent application, the corona and nitrous acid are so materially reduced that the air in room in which the X-ray tube is operated may be circulated by means of a blower or exhaust fan 5, within the room itself, without the detection of any undesirable or harmful amount of ozone and nitrous acid, and the tube may be operated continuously in an apparatus built after my invention, in a hospital treatment room, or the like, without the slightest inconvenience, and with the perfect comfort of the patient, which is a striking improvement over the prior art.

As illustrative of how my invention is used in hospitals and the like, I have shown a table illustrated in Figs. 5 and 6, which may be raised and lowered by a motion established at 28, and transmitted by means of' mechanical devices, such as 29, 30 and 31,

and the like. The patient lies on the table surface 32, and the said table is placed with such reference to apperture 8 in Fig. 1 as will allow the X-rays to impinge upon the desired anatomical part of the patients body.

about the axis of the tube.

It will be appreciated upon reference" to Fig. 2, and in general, that the tube-holder and patient may be moved in such ways and by such means with reference one to the other, as to give the desired X-ray dosages at such angles and in such positions as the operator may desire.

What I claim is:

1. In an X-ray device, means for supporting an X-ray tube and surface-characteristicmeans for substantially eliminating the production of corona about said tube at operating voltage thereof.

2. In an electrical circuit, the combination of an X-ray tube, and an electrostatic shield external of said tube at a potential between that of the electrodes of the said tube and having surface-characteristic-means for substantially eliminating the production of corona at operating voltages of said tube.

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3. In a high voltage apparatus, an electrostatic shield, an X-ray tube with surfaces and terminals co-operative with said electrostatic shield having geometrical figures of such physical contour as to substantially eliminate ionization at operating voltages of the said apparatus, thereby practically eliminating corona.

4. In an apparatus of the class described comprising an electrostatic shield, an X-ray tube co-operative with said electrostatic shield and an electric potential source for causing such co-operation, said tube and said shield having surfaces of curvature sulficiently remote from the curvatures which generate substantial corona at the applied potential under operation to substantially eliminate objectionable corona.

5. In a high voltage apparatus comprising an X-ray tube, means for holding same, said tube and said means comprising a plurality of parts being provided with surface-characteristic-means for collectively reducing the density of the electrostatic field determining the corona-formation point of said field, at operating voltages of said tube.

6. In a high potential apparatus of the class described comprising an X-ray tube, an electrostatically co-operative shield and an electrical potential source causing such cooperation, certain parts of said tube and said shield being of opposite polarity when the said tube is being operated, and being spaced laterally and longitudinally, and having surfaces of curvature sufficiently near the corona point and sufliciently removed from the spark-over point of the electrostatic field of the said curved surfaces in their predetermined space relations, to prevent substantial formation of corona in and about the said apparatus under operating voltages thereof.

7. In an X-ray device, means for supporting an X-ray tube and a cylindrical electrostatic shield disposed thereabout and forming an X-ray protective screen for the 'X-rays generated by the said tube, and comprising means for improving the electrostatic-fielduniformity about the walls of the said tube.

8. An electric discharge apparatus comprising the combination with an electric discharge device, of a hollow body surrounding said device, said body having such dimensions and such form relative to the shape of said device and being so disposed with respect thereto as to equalize the electrostatic field distribution in and about said apparatus when high potentials are impressed upon said device.

9. An electric discharge apparatus comprising the combination with an electric discharge device, of an electrostatic shield surrounding said device, said shleld having such dimensions and such form relative to the shape of said device and being so disposed with respect thereto as to equalize the electrostatic field distribution in and about said apparatus when high potentials are impressed upon said device.

10. In an X-ray device, means for supporting an X-ray tube and an electrically-com ductive X-ray protective shield about said tube and at a potential between that of the electrodes of said tube, substantially con centrically cylindrical with the axis of the electrodes of said tube and remotely disposed therefrom, whereby intense electrostatic-field distribution about the walls of the said tube is substantially eliminated.

11. In an X-ray device, a hollow cylindrical member of electrically conductive material at ground potential, electrical insulating wall bushings projecting through said member and supporting an X-ray tube of fixed over-all dimensions within aforesaid member and with space relations between said tube and said shield, whereby the electrostatic field about the said tube is substantially equalized.

12. In an X-ray device, an X-ray tube, means for supporting same within a substantially concentric hollow cylindrical electrostatic shield and X-ray absorbing screen, Wall bushings passing through said shield and electrical conductors in said bushings supplying excitation energy for said tube from a high potential source, and means for supply and exhaust of cooling medium to said tube; whereby said tube may operate within equalized electrostatic fields and said medium may flow unobstructedly to and by the walls of the said tube.

.13. In an X-ra device means for: supportin an u fifia'fimi electrostatic shield of le lly conductiuamaterial at a pt entialjgetween that of theelectrodes 6 siaid ltpbe and surrounding said tube and high tension terminals remotely disposed from the field of X-ray action and passing through said shield.

14:. In a device of the class described, an X-ray tube with members co-operating electrostatically with neighboring members of an electrostatic shield at differences of elec trical potential, said tube and said members integral over all configurations presenting rounded contours on substantially all portions efiectively within the high potential electrostatic field caused by the said dilferences of electric potential, whereby corona is substantially eliminated, one member forming a terminal for the said tube and being hollow.

15. In a device of the class described, an X-ray tube and X-ray tube supporting members having configurations presenting a rounded contour on substantially all portions effectively within the high potential electrostatic field, said members comprising hollow conducting shells.

16. In a device of the class described, X- ray tube-terminal supporting members comprising shells with rounded sections and recessed to receive terminals of the X-ray tube.

17. In an electric discharge apparatus, the combination with an electric discharge device, of electrically conductive means for supporting said device and. means associated with said supporting means permitting expansion and contraction of said device While maintaining electrical contact therewith, said supporting means having a geometric configuration of such a nature as to prevent corona.

MoN'rFoan MORRISON.

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