US 3389253 A
Description (OCR text may contain errors)
June 18, 1968 P. w. KOK 3,389,253 X-RAY APPARATUS FOR SELECTIVELY PRODUCING A STEREOSCOPIC 0R MONOSCOPIC X-RAY BEAM 2 Sheets-Sheet 1 Filed June 10, 1965 Fin 2 57mm N 28 l o f F/LANEA/T .SUPPL Y 30/ INVENTOR.
PIETER IV- KOK AGENT June 18, 1968 P. w. KOK
X-RAY APPARATUS FOR SELECTIVELY PRODUCING A STEREOSCOPIC OR MONOSCOPIC X-RAY BEAM 2 Sheets-Sheet 2 Filed June 10, 1965 Fly- 3 5 m. R M 0 4 R w 5 0 a I i r V n H mm TA w a 3 mm 2 44 m m m L 6 7 4 L 4 Q 000 E w PIETER W KOK AGE NI United States Patent 3,389,253 X-RAY APPARATUS FOR SELECTIVELY PRODUC- 12 STEREOSCOIIC 0R MONOSCOPIC X-RAY 4 Pieter Willem Kolr, New Milford, N.J., assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed June 10, 1965. Ser. No. 462,804 8 Claims. (Cl. 250--61) ABSTRACT OF THE DISCLOSURE A stereoscopic X-ray device is constructed with three electron generating cathodes cooperating with three corresponding anode focal spots. Two of the spots serve as stereoscopic beam emanation points because their respective associated cathodes are coupled to an alternating phase displaced voltage. The third cathode-anode focal spot generates a monoscopic X-ray beam having a higher intensity relative to either of the stereoscopic beams. A switching mechanism serves to selectively couple either stereo or monoscopic cathodes to the appropriate energizing source.
This invention relates to stereoscopic X-ray apparatus and particularly to the design of an X-ray tube employing a stereoscopic mode of operation.
Multiplane stereographic X-ray techniques are ex tremely valuable in performing various types of diagnostic analysis. One example would be cardiovascular studies wherein an accurate perspective or depth measurement would be crucial in providing a satisfactory cardiographical indicator.
A disadvantage of conventional stereographic techniques is the danger of providing a patient with dual X- ray beam irradiation, necessary to obtain a bi-level radiographic view. Further, the method of alternating between a pair of single X-ray beams necessitates the inconvenience of having to take dual radiographs of a single area at separate times therey causing inconvenience as well as nullifying the cardinal advantage of stereoscopy; a simultaneous biplanar view.
In certain applications, it becomes desirable to utilize conventional X-ray techniques in conjunction with or alternately to stereoscopic viewing, for instance, where a monoscopic or single 'high intensity X-ray beam projection is desired. In such instances, a second apparatus employing a high intensity beam and thereby requiring a second high potential source is necessary at obviously greater expense and inconvenience.
Various techniques have been developed which provide X-ray stereoscopic effects. An example of such a technique may be found in co-pending US. application Ser. No. 429,377, filed Feb. 1, 1965 and assigned to the assignee of the present invention. In the co-pending application, a switching circuit is provided to control two X-ray tubes for a stereoscopic effect.
An object of the present invention is to provide a single X-ray analysis tube capable of stereoscopic effect.
A further object of the invention is to provide a tube capable of either stereoscopic X-ray analysis or conventional monoscopic X-ray analysis.
A still further object of this invention is to provide a circuit wherein the operation of an X-ray tube may be selectively switched from stereoscopic analysis to conventional X-ray analysis.
Another object of the invention is to provide a high intensity monoscopic conventional X-ray apparatus in the same X-ray envelope as the stereoscopic X-ray beam generator.
3,389,253 Patented June 18, 1968 These and further objects of the invention will appear as the specification progresses and will be pointed out in the claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and the best mode contemplated of applying that principle.
In accordance with the operational principle of our invention, a highly evacuated X-ray tube envelope is pro vided with an anode and three cathodes. A two position switching circuit in its first position transmits a pair of oppositely phased alternating high voltage potentials to a corresponding pair of cathodes within the X-ray tube envelope. In this manner an alternating, phase-displaced, dual X-ray beam is derived from the tube for stereoscopic analysis purposes. When conventional monoscopic X-ray beams are desired for cinefluorographic analysis and the like, the switching circuit may be placed in its alternate position, thereby placing a constant potential difference between a third cathode and the anode. The stereoscopic cathodes are now electrically isolated, and the potential difference between the third cathode and anode generates a single conventional X-ray beam.
In an alternative embodiment, control grids are utilized to control the anode-cathode current flow. In further embodiments, a combination of switching and controlling grid circuits may be used.
The invention will now be described in greater detail with reference to the accompanying drawing wherein:
FIG. 1 shows a symbolic representation of the relative positioning of the beam focal points on the face of an anode in accordance with the invention.
FIG. 2 shows a preferred form of switching circuit compatible with the multicathode X-ray tube in accordance with the present invention. I
FIG. 3 shows a dual tube X-ray tank unit utilized f0 stereoscopic analysis in accordance with the present invention.
FIG. 4 shows an alternative form of X-ray tube control and switching circuit in accordance with the present invention.
Referring to FIG. 1 of the drawing, a symbolic representation of a target anode 10 is shown having thereon the relative position locations of a pair of stereo X-ray focal spots 12 and 14 spaced one from the other by a predetermined distance which may, by way of example, be approximately three inches. When the tube is operated in a conventional X-ray mode, a third focal spot 16, emitting X-rays of greater intensity relative to the X-rays emitted from the pair of stereo focal spots 12 and 14 is formed on the anode surface 10. As shown, for maximum effectiveness and full loadability, the location of the third focal spot is preferably along the center line of the target anode.
Referring to FIG. 2, there is shown an X-ray tube 18 having an anode 20 which may be of the rotating type, with forced air or liquid cooling, and having a suitable target material such as tungsten. The tube also includes first and second stereo cathodes 22 and 24 and a conventional high intensity X-ray cathode 26. The cathodes are directly heated by a standard filament power supply, not shown. Filament power isolation transformers 28, 30 and 32 are provided for the respective cathodes. The selective operation of the X-ray tube is determined by a two positioned ganged switching section 34 having a first position for stereoscopic mode and a second position for cine or conventional X-ray mode. The synchronous switching section 34 comprises a first switch A, a second switch B, a third switch C, and a fourth switch D. A fifth switch E is provided to disconnect the filament supply to certain cathodes as will be discussed in greater detail below. The circuit switches of the ganged switching section 34 is illustrated in the stereoscopic mode.
A high voltage transformer is provided having a primary winding (not shown) and a secondary winding 36 with a grounded center tap 38. A first alternating high voltage level appears along the output line 40 of the transformer and, during stereo mode, is directed to a stereo cathode 24 through switch B of the switching section 34. A second counterphased alternating high voltage level, of the same magnitude as the first but phase displaced 180 degrees therefrom, appears along the output line 42 of the transformer and is connected to the other stereo cathode 22 through switch D of the switching section 34. During this period switch A serves to place the anode 20 at ground potential, while switch C places the conventional X-ray cathode 26 at ground potential.
A full wave rectifier 44 is connected across the transformer secondary 36. When the switching section 34 is placed in cine or conventional X-ray mode position, a high DC positive potential level is placed on the anode 20 through switch A while a high DC negative potential is placed on the conventional X-ray cathode 26 through switch C. At the same time, switches B and D serve to electrically connect the stereo cathodes 24 and 22 to the cathode 26, thereby placing each at the same potential level. Discharge of the stereoscopy cathodes 22 and 24 during cine mode is prevented by disconnecting the cathodes 22 and 24 from the filament power source in any conventional manner. For example, the cathodes 22 and 24 could be disconnected by the provision of a further switch E which may be mechanically synchronized with the switching section 24 for convenience if desired.
In operation, and assuming by way of example an alternating potential operating level of 75 kv. appearing at the secondary 36 of the transformer, when the switching section 34 is in the stereo mode, a relative anode-cathode potential difference of 75 kv. appears alternately on each of the stereo cathodes. When the switching section 34 is placed in the cine or conventional X-ray mode, a relative anode-cathode potential difference of 150 kv. appears on the conventional X-ray cathode 26. The increased potential difference over that of the stereo cathodes results in the projection of a very high intensity single X-ray beam for conventional X-ray projection.
It will be understood that the anode may be positioned in any known manner for beam. projection. For example, the cathodes may be aligned with respect to the tube envelope while the anode is set on an angle to produce the necessary incidence angle for the X-ray beam.
In an alternative embodiment shown in FIG. 3 the stereoscopic effect may be created by utilizing an X-ray tank unit 46 having therein a high voltage transformer having a primary winding (not shown) and a secondary winding 36, a first X-ray tube 48 and a second X-ray tube 50 mounted in counterphase with the first tube. It is apparent that the two tubes may be combined within a single glass envelope or used separately as desired. An alternating potential 52 of preferably 60 cycles per second is supplied from the secondary 54 of the high voltage transformer. The unit is self-rectifying due to the diode nature of the X-ray tubes and two X-ray beam sources are thereby created having an aggregate output of 120 pulses per second. The tubes may be physically positioned so that the resultant stereoscopic beam foci are as shown in FIG. 1. The conventional X-ray source if desired could be switched in by means of a third X-ray tube, operated as described in connection with FIG. 2.
Referring to FIG. 4 of the drawings, there is disclosed an alternative embodiment of the invention wherein a pair of stereoscopic control grids 54 and 56 are inserted between the anode 20 and the stereoscopic cathodes 22 and 24 respectively. A conventional X-ray beam control grid 58 is inserted between the anode 20 and the conventional X-ray cathode 26. A grid bias control unit 60 receives a pulsating potential B, having, for example, a repetition rate of 100 kilocycles, on the primary of an isolation transformer 62. The secondary of the transformer 62 applies the bias potential via a rectifying diode 64 and a smoothing capacitor 66 to the control grid 56. Similarly constructed units 68 and 70 apply biasing potentials to control grids 58 and 54 respectively. A constant direct potential V is impressed along anode line 72 and cathode lines 74, 76 and 78, and the resultant electron flow between anode and cathodes is controlled by means of the bias levels of the bias control units. The anodecathode potentials may, by way of example, be kv. and 75 kv., respectively.
In operation, when stereoscopic X-ray beam generation is desired, the bias levels of control units 60 and 70, and therefore of control grids 56 and 54, respectively, are varied synchronously at a phase difference of degrees so that a stereo X-ray beam is produced per unit cycle as was explained in connection with FIGURE 2. The bias level of control unit 68, and therefore of control grid 58, is maintained at a maximum negative level so as to suppress the fiow of electrons from the cathode 26, the conventional X-ray beam cathode. When conventional X-ray beam generation is desired, control units 60 and 70 place a negative bias on control grids 56 and 54 respectively, thereby suppressing the flow of electrons from the stereoscopic cathodes 24 and 22 to the anode 20. A varying potential bias is placed on the control grid 58 from the control unit 68 thereby allowing only a single electron flow path from the cathode 26 to the anode 20, and only one beam is generated, the conventional X-ray beam.
It will be apparent to those skilled in the art that other modes of effecting the changeover between conventional X-ray beam generation and stereoscopic beam generation are feasible. For example, a combination of the above described modes may be employed wherein control units and control grids are provided for the stereoscopic cathodes only, the conventional cathode 26 being switched in or out of the circuit as desired by high potential cathode switching or filament supply switching. Alternately, only one control unit and grid is supplied for the conventional X-ray cathode while the two stereoscopic cathodes are switched in or out of the circuit as desired by similar high potential cathode switching or filament supply switching.
While we have described our invention in connection with specific embodiments and applications thereof, other modifications will be apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.
What I claim is:
1. X-ray apparatus for selectively producing a stereoscopic X-ray beam and a. monoscopic X-ray beam, comprising an X-ray unit having at least one anode with first, second and third focal spots, first, second and third cathodes each defining respectively, a first, second and third electron discharge path respectively corresponding to said first, second and third focal spots on said anodes, first means applying a potential across said first and second electron discharge paths to provide a pair of alternating stereoscopic X-ray beams emanating from said first and second anode focal spots, and second means applying a potential along said third electron discharge path to provide a controlled monoscopic X-ray beam emanating from said third focal spot with a respectively greater intensity than either of said stereoscopic X-ray beams.
2. The combination of claim 1 wherein said third electron discharge path focal spot is positioned on said anode substantially along an axis passing through the geometric center of said anode.
3. X-ray apparatus for selectively producing a stereoscopic X-ray beam and a monoscopic X-ray beam, comprising an X-ray tube having an anode with first, second and third focal spots, first second and third cathodes, each defining respectively a first, second and third electron discharge path each said path respectively corresponding to said first, second and third focal spots on said anodes, a source of potential, first control means selectively connecting said source of potential between said anode and said first and second cathodes to apply energy from said source along said first and second electron discharge paths to provide a pair of alternating stereoscopic X-ray beams emanating from said first and second focal spots, and second control means selectively connecting said source of potential between said anode and said third cathode to apply a potential from said source along said third electron discharge path to provide a conventional X-ray beam emanating from said third focal spot with a relatively greater intensity than either of said stereoscopic X-ray beams.
4. X-ray apparatus for selectively producing a stereoscopic X-ray beam and a monoscopic X-ray beam, comprising an X-ray tank unit having at least one anode having first, second and third focal spots, first and second cathodes for applying electrons to said anode to produce a pair of phase-displaced and spatially separated stereoscopic X-ray beams emanating from said first and second focal spots, and a third cathode for applying electrons to said anode to produce a monoscopic X-ray beam, a source of potential, switching means selectively connecting said source of potential to said first and second cathodes for producing said pair of phase-displaced and spatially separated stereoscopic X-ray beams, and to said third cathode for producing said monoscopic X-ray beam.
5. The combination of claim 4 wherein there is provided a plurality of anodes, each of which forms an electron path with an associated one of said cathodes.
6. X-ray apparatus for selectively producing a stereoscopic X-ray beam and a monoscopic X-ray beam, comprising an X-ray tube having first and second electron discharge paths defined by first and second electron emitting cathodes and first and second anode focal spots for generating said stereoscopic X-ray beam from said first and second anode focal spots, and a third electron discharge path defined by a third electron emitting cathode and a third anode focal spot for generating said monoscopic X-ray beam from said third anode focal spot, a pair of counterphased alternating voltages, a source of bi-polar voltage, switching means connecting each of said counterphased alternating voltages along said first and second electron discharge paths respectively for producing said stereoscopic X-ray beam, and alternatively connecting said source of bi-polar voltage to said third electron discharge path respectively for producing said monoscopic X-ray beam, said bi-polar voltage having a magnitude relatively greater than either of said pair of counterphased alternating voltage thereby resulting in said monoscopic X-ray beam emanating from said third focal spot with a relatively greater intensity than either of said stereoscopic X-ray beams.
7. X-ray apparatus for selectively producing a stereoscopic X ray beam and a monoscopic X-ray beam. comprising an X-ray tube having an anode with first, second and third focal spots, first and second cathodes for producing an electron flow resulting in a stereoscopic X-ray beam, emanating from said first and second focal spots, and a third cathode for generating an electron flow resulting in a monoscopic X-ray beam emanating from said third focal spot, each of said cathodes together with said anode defining respective electron discharge paths, control means for varying the discharge in each of said electron discharge paths, first energizing means supplying a pair of oppositely phased alternating potentials, means connecting each of said pair of alternating potentials to a respective one of said control means for producing said stereoscopic X-ray beam from said first. and second cathode electron discharge paths, second energizing means, and means connecting said second energizing means to said control means for producing said monoscopic X-ray beam from said third cathode electron discharge path and emanating from said third focal spot with a relatively greater intensity than either of said stereoscopic X-ray beams.
8. The combination of claim 7 wherein at least one of said control means comprises a control gn'd.
References Cited UNITED STATES PATENTS 3,158,745 11/1964 Stanhope 250-99 3,244,878 4/1966 Stein et al. 250-- 3,250,916 5/1966 Rogers 250-60 3,309,519 3/1967 Euler et al. 250-60 RALPH G. NILSON, Primary Examiner. A. L. BIRCH, Assistant Examiner.