US 3149257 A
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Description (OCR text may contain errors)
219-121 MTROS Sept. 15, T1964 l I I I D. E. WINTERMUTE X-RAY DEVICES FOR USE ON THE E-IUMAN BODY Filed April 25, 1962 I If A TTDRNE'YS .iinite This invention relates to new and useful improvements in X-ray devices for use on the human body.
The invention is particularly concerned with new and improved X-ray tubes or X-ray generating apparatus adapted for use on the human body and which may be employed for generating or supplying continuous X-rays of conventional intensity or intermittent X rays of considerably reduced irradiation properties.
Medically speaking, there are two principal uses of X-rays as far as examination of human beings is concerned, the first being the use of X-rays for exposing an X-ray film negative in somewhat the manner that conventional photographs are taken. The second primary use is in the fluoroscopy of persons in which an instantaneous X-ray image is temporarily formed upon a suitable, sensitive screen elernent. In the first instance, the exposure periods are relatively short, and, within reason, no irradiation hazards are involved. In the second instance, however, using X-rays of the same intensity, the irradiation hazard is considerably increased for the reason that the exposure times are much greater. It is not feasible to vary the nature of the power supply to the X-ray tube in order to reduce the radiation hazard for the longer exposures since alteration of the electrical current and especially the electrical voltage will result in the production of X-rays of a nature quite harmful to human tissue. On the other hand, it is quite possible to obtain a completely adequate fluoroscopic examination utilizing X-rays of a nature as to expose the subject to greatly decreased irradiation.
In general there are two considerations in determining the conservative or medically safe amount of X-ray exposure to which a person may be exposed without ell'ects harmful to a degree as to be contraindicated. An excessive application of X-rays at any one time tends to result in almost immediate and permanent tissue damage. and hence, the first consideration is the amount of X-ray emanation to which a person may be safely subjected during one treatment or examination. X-ray emanations also have a cumulative eiiect, and therefore the second consideration is the total quantity of X-ray exposure a person may safely receive on any portion or area of his or her body over the space of normal life expectancy.
This invention does not seek to alter or change the degree of X-ray exposure involved in the obtaining of conventional X-ray films or film negatives, but it does accomplish a marked reduction in such exposure during fiuoroscopy or other medical procedures requiring less intensity of quantity of exposure and does so while permitting use of the same X-ray tube or apparatus for both or all such procedures.
It is, therefore, one object of this invention to providean improved X-ray apparatus for use upon the human body with which the operator may selectively and readily obtain continuous X-rays of a conventional nature, or intermittent X-rays of greatly reduced intensity.
atent Another object of the invention is to rovide an imparable to conventional X-ray tubes now presently available on the open market.
Still another object of the invention is to provide improved X-ray devices of the character described which may be readily employed in existing X-ray equipment in conjunction with or for replacing conventional X-ray tubes.
An important object of the invention is to provide an improved X-ray tube employing a revolving anode having a continuous emitting surface and an intermittent emitting surface, coupled with means for eiectrostatically deflecting the electron beam flowing from the cathode to the anode so as to cause the beam to impinge selectively upon the continuous or the non-continuous portions of the anode for production of continuous and conventional X-ray or intermittent X-rays.
A further object of the invention is to provide an improved X-ray device for use on the human body with which the X-ray emanations of a conventional X-ray tube may be employed for normal X-ray film exposure, or in the alternative, with which emanations of reduced intensity may be produced for iiuoroscopy and similar uses.
A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.
The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing wherein examples of the invention are shown, and wherein:
FIG. 1 is a vertical, longitudinal sectional view or' an X-ray tube constructed in accordance with this invention,
FIG. 2 is a front elevational view of the anode of the tube shown in FIG. 1, the view being taken on the line 2-2 of FIG. 1,
FIG. 3 is a schematic view of a modified X-ray device constructed in accordance with this invention and adapted to carry out the objects thereof, and
FIG. 4 is a top plan view of the intermitter element of the modification shown in FIG. 3 and taken upon the line 4- 3 of FIG. 3.
In the drawings, the numeral 10 designates in general an X-ray tube of the revolving anode type, the general arrangement of such tube being shown in US. Letters Patent No. 2,233,194, issuedto Atlee et al., and in US. Letters Patent No. 2,648,025, issued to Agule. The tube structure in general includes an enclosing envelope 11, a fixed cathode 12 and a revolving anode 13 operated by a motor rotor 14 completely enclosed within the envelope 11 and actuated inductively by external coils 15. The anode 13 is disk-like in shape with a beveled or chamfered peripheral portion 16 facing the cathode 12 and forming the target area for the electron stream flowing from the cathode 12 and generating X-rays which are propagated or emitted laterally or transversely of the X- ray tube.
In my improved form of a revolving anode X-ray tube the beveled target area of the anode is divided into a continuous target area or section 17 and an intermittent target area or section 18. Although the intermittent area may be formed by means of suitably sized and spaced perforations in the radially inwardly disposed portion of the target area 16, it is more readily and economically formed by means of a plurality of peripheral notches 19 cut into the radially outwardly disposed portion of the target area 16 as shown in FIG. 2. The notches 19 may be suitably dimensioned and spaced in accordance with the degree to which the X-ray emission is to be modified or reduced. The tube is also provided with an auxiliary electrode 20 disposed adjacent the path 21 of the electron stream flowing from the cathode 12 whereby a negative charge may be placed upon the electrode 20 to cause the electron stream 21 to deflect from its normal path and away from the electrode 26, or a positive charge may be placed on the electrode 20 to cause the electron stream 21 to deflect away from its normal path and toward the electrode 20. Thus, depending upon whether the notches 19 are employed, or more inwardly positioned openings, the electrode stream may normally fall upon either the continuous or the intermittent portions of the target area 16 and may be deflected inwardly or outwardly as may be desired to fall upon the second portion of the target area.
With this arrangement, the X-ray tube may be operated with the electron stream falling upon the continuous portion 17 of the target area 16 to produce conventional and continuous X-ray emission, or by suitably charging the electrode 20, the electron stream 21 may be deflected to fall upon the intermittent portion of the target area 16 and thus produce intermittent X-rays which necessarily are of reduced, cumulative radiation values. Obviously, the notches 19 may be made very narrow to reduce the X-ray emission intensity very slightly, or they may be made very wide with divergent side walls to bring the X-ray emission intensity to a very low value. Obviously, intermediate values may also readily be obtained as may be desired, these values being a" function of the size and shape of the notches l9 and the speed of revolution of the anode 13.
No attempt has been made to show complete and conventional shielding of the X-ray tube, there being shown more or less schematically an auxiliary target 22 upon which those portions of the electron beam passing through the notches 19 may impinge and with which any resultant emanations are directed into a suitable shielded trap 23. Such shielding and trapping of stray X-ray emanations is conventional and well-known in this art. Further, the tube may be supplied in conventional manners with suitable coolants directed to one or more locations, and obviously, the means for driving or revolving the anode 13 may be of any suitable or desirable nature.
In the operation of the tube, the electrode 20 is suitably charged or not charged, dependent upon the design of the tube, to cause the electron stream 21 emanating from the cathode 12 to fall upon the continuous portion 17 of the target area 16 of the revolving anode. With this arrangement, the tube is functioning as any other revolving anode tube and producing X-rays suitable for very short ex posures of X-ray film. Now, assuming that a fluoroscopic examination of a patient is to be carried out, the electrode 20 is suitably charged or uncharged, again in accordance with the particular mode of operation selected for the tube, to cause the electron stream 21 to impinge upon the intermittent portion 18 of the target area 16 whereby conventional and relatively unharmful X-rays are produced, but are produced in an intermittent fashion so that the overall cumulative exposure of the patient to the X-rays is greatly reduced, and yet, by means of which X-rays of sufiicient intensity are supplied to enable a fluoroscopic examination to be carried out. As pointed out hereinabove, such examinations are normally of considerably longer duration than occur in the taking or exposing of X-ray films, and yet the intermittent nature and reduced intensity of these fluoroscopic X-rays is reduced to the point that the well being of the patient is not endangered even though there is exposure to X-rays over a somewhat longer period of time. There are certain limits as to permissible variation in the nature of X rays being employed upon human beings, and it is not a matter of riifcingthe intensity of the X-rays in the same manner that one woulddim an incandescent electric light bulb by means of a rheosta?The X-rays must be generated under certain minimum values of voltage if the patient is not to be endangered, and the present invention allows the maintenance of these minimum values minimizing the total exposure of the patient to X-rays at one time as well as the total cumulative exposure of the patient to X-rays over a period of months or years. 1
In both settings or adjustments of the subject tube, the continuous or intermitent X-rays are directed laterally through the side wall of the envelope 11, in the particular embodiment shown, the continuous rays following the fiow path 24 and the intermittent rays following the flow path 25. e
The invention may also be applied to a conventional X- ray tube not having a revolving anode, such a tube being shown at 26 in FIG. 3 and having a cathode 27 emanating an electron beam against an anode 28 for lateral emission of X-rays as indicated at 29. A screen 30 formed of lead or other suitable material restricts the X-ray beam and directs it through the peripheral notches 31 of a revolving screen or shield plate 32. As shown in FIG. 4, the peripheral notches 31 of the plate 32 may be suitably dimensioned and spaced to provide the desired diminution of intensity of the X-rays, the plate assembly 32 being provided with a suitable driving or revolving element 33 and the entire assembly being retractable, as by the screwthreaded rod 34 and handle 35 for withdrawal of the peripheral portion of the plate 32 from the path of the X-rays and the production of continuous and conventional X-ray emission. The functioning of this second form of the invention is the same as that of the first described form, the operator being enabled to utilize conventional and continuous X-ray emission or intermittent emission of such intensity as may be required. Of course, a number of the plates 32 may be provided with peripheral notches of different sizes and different spacings for differing alteration in the intensity of the X-ray emission.
In both forms of the invention, the size of the notches 19 of the revolving anode 13, or of the notches 31 of the a revolving shield plate 32, may be so correlated with the speed of revolution of the anode or the shield plate that the X-rays are not blocked oil for a period of time greater than that for which the human eye is capable of retaining a retinal image. Thus, though the picture obtained during fiuoroscopy is actually intermittent, it appears to the human observer to be continuous. Obviously, in taking motion pictures of a fluoroscope screen suitable synchronization of the camera may be utilized if necessary.
The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.
What I claim and desire to secure by Letters Patent is:
I. An X-ray tube for use upon the human body including a tube envelope, a cathode Within the envelope for emitting a stream of electrons, a revolving anode in the envelope having a target area upon which the stream of electrons impinges, said target area including a continuous section and a non-continuous section for selective emission of continuous X-ray emanations and intermittent X-ray emanations, and means for shifting the path of the stream of electrons from one section of the target area of the anode to the other section thereof for selective continuous and intermittent emission of X-ray emanations.
2. An X-ray tube for use upon the human body including, a tube envelope, a cathode in the envelope for emission of an electron stream, an anode mounted for revolution in the envelope, means for revolving the anode in the envelope, the anode having a target area for impingement of the electron stream flowing from the cathode, said target area of the anode including a continuous section and a non-continuous section, and means for shifting the path of the stream of electrons flowing from the cathode to the anode to cause the stream of electrons to impinge selectively upon the continuous section and the non-continuous section of the target area of the anode.
3. An X-ray tube for use upon the human body including, a tube envelope, a cathode in the envelope for emitting a stream of electrons, an anode mounted for revolution in the envelope, means for revolving the anode in the envelope, the anode having an annular target area for impingement of the electron stream flowing from the cathode, the annular target area of the anode including a continuous section and an non-continuous section for selective impingement of the electron stream upon said sections for continuous and non-continuous emission of X-ray emanations, and means for shifting the path of the electron stream flowing from the cathode to the anode for selective impingement upon the continuous and non-continuous sections or" the target area of the anode.
4. An X-ray tube at set forth in claim 3 wherein the non-continuous section of the annular target area of the anode is formed by cutaway portions extending inwardly from the periphery of the anode toward the continuous section.
5. An X-ray tube for use upon the human body including, a tube envelope, a cathode in the envelope for emitting a stream of electrons, an anode mounted for revolution in the envelope, means for revolving the anode in the envelope, the anode having an annular marginal target area for impingement or the electron stream thereon, the target area including an inner annular continuous section for continuous imningenient of the electron stream and continuous emission of X-ray emanations, the target area also having an outer annular non-continuous section formed by notches cut radially inwardly from the periphery of the anode toward the continuous impingement section, the outer non-continuous impingement section being positioned for impingement of the electron stream thereon and the intermittent emission of X-ray emanations, and means for deflecting the electron stream from one impingement section to the other.
6. An X-ray tube as set forth in claim 5, and emanation trap means for trapping emanations caused by those portions of the electron stream passing through the peripheral notches.
References Cited in the tile of this patent UNITED STATES PATENTS 2,594,564 Kehril Apr. 29, 1952