EP0063190A1 - Microfocus X-ray tube - Google Patents
Microfocus X-ray tube Download PDFInfo
- Publication number
- EP0063190A1 EP0063190A1 EP81301744A EP81301744A EP0063190A1 EP 0063190 A1 EP0063190 A1 EP 0063190A1 EP 81301744 A EP81301744 A EP 81301744A EP 81301744 A EP81301744 A EP 81301744A EP 0063190 A1 EP0063190 A1 EP 0063190A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ray tube
- target anode
- electron beam
- microfocus
- rays
- 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.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J35/00—X-ray tubes
- H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
- H01J35/28—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by vibration, oscillation, reciprocation, or swash-plate motion of the anode or anticathode
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05G—X-RAY TECHNIQUE
- H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
- H05G1/08—Electrical details
- H05G1/66—Circuit arrangements for X-ray tubes with target movable relatively to the anode
Definitions
- This invention relates to microfocus X-ray tubes such as are used to take medical X-rays.
- the electron beam is focused on an extremely small point on the target, which has the medical advantage that the X-ray silhouette is very clear and crisp.
- the highly dense, small spot of electrons quickly melts the target no matter what kind of cooling device is used, and therefore either the X-ray target is consumed in one use or fewer electrons are used in the beam than would otherwise be desirable.
- the exposure time must be relatively long to get enough X-rays to form the picture because the rate of X-ray production is so small.
- X-ray tubes of the type used in taking medical X-rays are known in which similarly elaborate devices are employed to bring a cooling fluid into thermal contact with the target anode during impingement of the electron beam.
- the cooling fluid may, for example, be water or air.
- X-ray tubes not suitable for use in taking medical X-rays, but suitable for use in X-ray crystalography, are known in which the target anode can be moved between impingements of the electron beam.
- Typical of these are the devices shown in U.S. patent no. 2,298,335, issued October 13, 1942, to Atlee, and U.S. patent no. 3,753,020, issued August 4, 1973, to Zingaro.
- Such devices include a plurality of separate target anodes made of different materials, and the devices permit the operator to alternate from one target anode to another to obtain different readings from the different types of anodes.
- U.S. patent no. 3,290,540, issued December 6, 1966 discloses an electron discharge tube having a movable cathode tape.
- the tape serves as an emissive element, and the tape can be incremented after it has become pitted from use.
- the pitting of an emissive cathode from use is very different, both physically and conceptually, from the melting of a portion of a target anode due to the impingement of an electron beam.
- the presently preferred embodiment of the subject invention comprises a conventional evacuated glass envelope 10 and a high voltage line 12, filament current wires 14, a heater cathode 16, and an electron beam collimator 18 which together constitute means for producing a dense, narrow electron beam 20.
- the subject X-ray tube preferably has a target anode in the form of a ribbon 22 trained around two spools 24 mounted within the X-ray tube on bracket 26.
- the ribbon 22 is preferably made of tungsten, but in any event the working surface of the ribbon 22 is made of a single anode material.
- a stepping motor 28 which is operatively connected to the spools 24 via a drive belt 30. Power for the motor 28 is supplied by motor wires 32, and the motor 28 and the target anode 22 are grounded by ground wire 34.
- the roughened portions of the ribbon 22 caused by impingement of the electron beam 20 are, of course, greatly exagerated in size for clarity.
- the roughened portions are approximately 50 microns in diameter, and their center-to-center distance (i.e., the amount by which the stepping motor 28 increments the ribbon 22 each time it is actuated) is approximately 100 microns.
- activation of the heater cathode 16 and the motor 28 is coordinated so that the ribbon 22 is stationary during production of X-rays 36, but a fresh portion of the surface of the ribbon 22 is presented to the electron beam 20 each time the X-ray tube is used.
- Each use of the X-ray tube therefore melts at least the surface portion of the spot on the ribbon 22 on which the electron beam 20 is focused, but the ribbon 22 is then moved on by a short distance, much in the fashion of a typewriter ribbon, before the X-ray tube is used again.
- FIG. 2 shows in schematic form exemplary means for coordinating the electron producing means and the ribbon advancing means.
- Such means comprises three ganged switches 38, 40, and 42 and three circuits, one of which is controlled by each of the switches.
- the ganged switches may be operated simultaneously by a single push button (not shown).
- One of the three circuits comprises a voltage source 44, the switch 42, and the filament current wires 14.
- Another of the three circuits comprises a high voltage generator 46 grounded at 48, the switch 40, and the high voltage line 12. Since these circuits are conventional, they will not be described further.
- the third circuit is not conventional, for it is the circuit which coordinates the first two circuits and the stepping motor 28. It comprises the switch 38, a battery 40 (which may be the same as battery 44), a timer 52, which may for instance be a two second timer, a pulse generator 54, a driver card 56, and motor wires 32.
- Activation of the ganged switches 40 and 42 causes generation of an electron beam lasting less than 1/10 of a second in the conventional manner.
- actuation of the switch 38 actuates the two-second timer 52.
- the pulse generator 54 emits a pulse which actuates the driver card 56, and the driver card 56 causes the stepping motor 28 to increment.
- the increment of the stepping motor 28 may, for instance, be 1.8°, and the spools 24 and the take-off spool connected to the stepping motor 28 are sized so that a 1.8° increment of the stepping motor causes the ribbon 22 to advance by approximately 100 microns. Since the time elapse between X-rays is much more than two second, the illustrated apparatus insures that a fresh portion of the surface of the ribbon 22 is presented to the electron beam upon each actuation of the beam.
- the target anode may take on shapes other than the illustrated ribbon shape. It may, for instance, be in the shape of a wheel or a cone. No matter what its shape, however, the common feature of'the invention is that the target is moved intermittently to present a new target area for each shot, but remains stationary during each shot.
- a particular advantage of the subject invention is that it is reusable, yet it generates a relatively large number of X-rays in a relatively short period of time from a narrowly focused electron beam.
- Another advantage of the subject invention is that it produces X-ray silhouettes which are very clear and crisp. In particular, since the X-ray silhouettes are made in a short time exposure, motion of the patient's organs does not smear the picture.
Abstract
Description
- This invention relates to microfocus X-ray tubes such as are used to take medical X-rays. In such X-ray tubes, the electron beam is focused on an extremely small point on the target, which has the medical advantage that the X-ray silhouette is very clear and crisp. However, the highly dense, small spot of electrons quickly melts the target no matter what kind of cooling device is used, and therefore either the X-ray target is consumed in one use or fewer electrons are used in the beam than would otherwise be desirable. In particular, it is highly desirable in medical X-ray work to use an extremely short exposure time so that the motion of the patient or of the patient's inside organs does not smear the picture. However, with prior-art microfocus tubes, the exposure time must be relatively long to get enough X-rays to form the picture because the rate of X-ray production is so small.
- The problems suggested in the preceding paragraph are not intended to be exhaustive, but rather are among many which tend to reduce the effectiveness of prior-art microfocus X-ray tubes. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that microfilm X-ray tubes appearing in the prior-art have not been altogether satisfactory.
- It is, therefore, a general object of the invention to provide a microfocus X-ray tube which will obviate or minimize problems of the type previously described.
- It'is a particular object of the invention to provide such a device which,is reusable, yet which generates a relatively large number of X-rays in a relatively short period of time using a narrowly focused electron beam.
- It is a further object of the invention to provide a microfocus X-ray tube wherein the X-ray tube comprises means for moving the target anode so that it is stationery during production of X-rays but a fresh portion of the surface of the target anode is presented to the electron beam each time the X-ray tube is used.
- It is another object of the invention to provide a microfocus X-ray tube wherein the target anode is in the form of a ribbon.
- Other objects and advantages of the present invention will become apparent from the detailed description of a preferred embodiment given hereinafter taken in conjunction with the accompanying drawings.
- Many X-ray tubes of the type used in taking medical X-rays are known which employ more or less elaborate devices to move the target anode during impingement of the electron beam, thereby distributing the heat generated by the electron beam over a portion of the surface of the target anode far in excess of the cross-sectional area of the electron beam. Representative of the awkward designs others skilled in the art have resorted to remove and deconcentrate the heat generated by the action of the electron beam on the target material is the device disclosed in U.S. patent no. 3,825,786, issued July 23, 1974, to Einighammer et al.
- Many other X-ray tubes of the type used in taking medical X-rays are known in which similarly elaborate devices are employed to bring a cooling fluid into thermal contact with the target anode during impingement of the electron beam. The cooling fluid may, for example, be water or air.
- Other types of X-ray tubes not suitable for use in taking medical X-rays, but suitable for use in X-ray crystalography, are known in which the target anode can be moved between impingements of the electron beam. Typical of these are the devices shown in U.S. patent no. 2,298,335, issued October 13, 1942, to Atlee, and U.S. patent no. 3,753,020, issued August 4, 1973, to Zingaro. Such devices, however, include a plurality of separate target anodes made of different materials, and the devices permit the operator to alternate from one target anode to another to obtain different readings from the different types of anodes. However, they do not cause the automatic substitution of one target anode for another after each use, and the operator could (an in many cases would) use the same segment of the same target anode many times before switching to a different target anode. Moreover, devices such as are disclosed in Atlee and Zingaro do not cause a different portion of each target anode to be used each time the user returns to a given target anode. If a fresh portion of the target anode is presented to the electron beam when a given target anode is used on a subsequent occasion, it would be accidental or incidental, not caused deliberately and consistently.
- Finally, U.S. patent no. 3,290,540, issued December 6, 1966, discloses an electron discharge tube having a movable cathode tape. The tape serves as an emissive element, and the tape can be incremented after it has become pitted from use. However, the pitting of an emissive cathode from use is very different, both physically and conceptually, from the melting of a portion of a target anode due to the impingement of an electron beam.
-
- Figure 1 is a perspective view of the presently preferred embodiment of an X-ray tube according to the invention.
- Figure 2 is a schematic diagram of control means for the X-ray tube shown in Figure 1.
- The presently preferred embodiment of the subject invention comprises a conventional evacuated
glass envelope 10 and ahigh voltage line 12, filamentcurrent wires 14, aheater cathode 16, and anelectron beam collimator 18 which together constitute means for producing a dense,narrow electron beam 20. Instead of the conventional conical target anode, however, the subject X-ray tube preferably has a target anode in the form of aribbon 22 trained around twospools 24 mounted within the X-ray tube onbracket 26. Theribbon 22 is preferably made of tungsten, but in any event the working surface of theribbon 22 is made of a single anode material. - Also mounted within the X-ray tube is a
stepping motor 28 which is operatively connected to thespools 24 via adrive belt 30. Power for themotor 28 is supplied bymotor wires 32, and themotor 28 and thetarget anode 22 are grounded byground wire 34. - The roughened portions of the
ribbon 22 caused by impingement of theelectron beam 20 are, of course, greatly exagerated in size for clarity. In fact, the roughened portions are approximately 50 microns in diameter, and their center-to-center distance (i.e., the amount by which the steppingmotor 28 increments theribbon 22 each time it is actuated) is approximately 100 microns. - In use, activation of the
heater cathode 16 and themotor 28 is coordinated so that theribbon 22 is stationary during production ofX-rays 36, but a fresh portion of the surface of theribbon 22 is presented to theelectron beam 20 each time the X-ray tube is used. Each use of the X-ray tube therefore melts at least the surface portion of the spot on theribbon 22 on which theelectron beam 20 is focused, but theribbon 22 is then moved on by a short distance, much in the fashion of a typewriter ribbon, before the X-ray tube is used again. - Figure 2 shows in schematic form exemplary means for coordinating the electron producing means and the ribbon advancing means. Such means comprises three ganged
switches voltage source 44, theswitch 42, and the filamentcurrent wires 14. Another of the three circuits comprises ahigh voltage generator 46 grounded at 48, theswitch 40, and thehigh voltage line 12. Since these circuits are conventional, they will not be described further. The third circuit, however, is not conventional, for it is the circuit which coordinates the first two circuits and thestepping motor 28. It comprises theswitch 38, a battery 40 (which may be the same as battery 44), atimer 52, which may for instance be a two second timer, apulse generator 54, adriver card 56, andmotor wires 32. - Activation of the ganged
switches switch 38 actuates the two-second timer 52. After elapse of the two seconds, thepulse generator 54 emits a pulse which actuates thedriver card 56, and thedriver card 56 causes thestepping motor 28 to increment. The increment of thestepping motor 28 may, for instance, be 1.8°, and thespools 24 and the take-off spool connected to the steppingmotor 28 are sized so that a 1.8° increment of the stepping motor causes theribbon 22 to advance by approximately 100 microns. Since the time elapse between X-rays is much more than two second, the illustrated apparatus insures that a fresh portion of the surface of theribbon 22 is presented to the electron beam upon each actuation of the beam. - Although not illustrated, it is within the contemplation of the invention for the target anode to take on shapes other than the illustrated ribbon shape. It may, for instance, be in the shape of a wheel or a cone. No matter what its shape, however, the common feature of'the invention is that the target is moved intermittently to present a new target area for each shot, but remains stationary during each shot.
- From the foregoing description of a microfocus X-ray tube in accordance with a preferred embodiment of the invention, those skilled in the art will recognize several advantages which singularly distinguish the subject invention from previously known devices. Some of those advantages are set forth below. However, while the following list of advantages is believed to be both accurate and representative, it does not purport to be exhaustive.
- A particular advantage of the subject invention is that it is reusable, yet it generates a relatively large number of X-rays in a relatively short period of time from a narrowly focused electron beam.
- Another advantage of the subject invention is that it produces X-ray silhouettes which are very clear and crisp. In particular, since the X-ray silhouettes are made in a short time exposure, motion of the patient's organs does not smear the picture.
- While the present invention has been illustrated by a detailed description of a preferred embodiment thereof, it will be obvious to those skilled in the art that various changes in form and detail can be made therein without departing from the true scope of the invention. Accordingly, the invention must be measured by the claims appended thereto and not by the foregoing preferred embodiment.
Claims (10)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE8181301744T DE3171782D1 (en) | 1981-04-21 | 1981-04-21 | Microfocus x-ray tube |
EP81301744A EP0063190B1 (en) | 1981-04-21 | 1981-04-21 | Microfocus x-ray tube |
AT81301744T ATE14953T1 (en) | 1981-04-21 | 1981-04-21 | MICROFOCUS X-RAY TUBE. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP81301744A EP0063190B1 (en) | 1981-04-21 | 1981-04-21 | Microfocus x-ray tube |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0063190A1 true EP0063190A1 (en) | 1982-10-27 |
EP0063190B1 EP0063190B1 (en) | 1985-08-14 |
Family
ID=8188281
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP81301744A Expired EP0063190B1 (en) | 1981-04-21 | 1981-04-21 | Microfocus x-ray tube |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0063190B1 (en) |
AT (1) | ATE14953T1 (en) |
DE (1) | DE3171782D1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0181194A2 (en) * | 1984-11-08 | 1986-05-14 | Hampshire Instruments, Inc | X-ray generating system |
CN103943443A (en) * | 2013-01-18 | 2014-07-23 | 通用电气公司 | X-ray source with moving anode or cathode |
US9520262B2 (en) | 2012-06-14 | 2016-12-13 | Siemens Aktiengesellschaft | X-ray source, method for producing X-rays and use of an X-ray source emitting monochromatic X-rays |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3290540A (en) * | 1964-04-16 | 1966-12-06 | Westinghouse Electric Corp | Electron discharge tube having a movable cathode tape |
GB1232160A (en) * | 1968-08-17 | 1971-05-19 | ||
US3753020A (en) * | 1971-11-26 | 1973-08-14 | Philips Electronics And Pharm | Multi-anode x-ray tube |
US3825786A (en) * | 1972-02-02 | 1974-07-23 | R Hauke | Method for increasing the power x-ray tubes and apparatus for carrying out the method |
US3836804A (en) * | 1971-11-19 | 1974-09-17 | Philips Corp | Slotted anode x-ray tube |
GB1436872A (en) * | 1972-05-08 | 1976-05-26 | Albert R D | X-ray source |
GB1505587A (en) * | 1974-05-15 | 1978-03-30 | Philips Ltd | Method of manufacturing an anode for an x-ray tube |
-
1981
- 1981-04-21 AT AT81301744T patent/ATE14953T1/en not_active IP Right Cessation
- 1981-04-21 DE DE8181301744T patent/DE3171782D1/en not_active Expired
- 1981-04-21 EP EP81301744A patent/EP0063190B1/en not_active Expired
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3290540A (en) * | 1964-04-16 | 1966-12-06 | Westinghouse Electric Corp | Electron discharge tube having a movable cathode tape |
GB1232160A (en) * | 1968-08-17 | 1971-05-19 | ||
US3836804A (en) * | 1971-11-19 | 1974-09-17 | Philips Corp | Slotted anode x-ray tube |
US3753020A (en) * | 1971-11-26 | 1973-08-14 | Philips Electronics And Pharm | Multi-anode x-ray tube |
US3825786A (en) * | 1972-02-02 | 1974-07-23 | R Hauke | Method for increasing the power x-ray tubes and apparatus for carrying out the method |
GB1436872A (en) * | 1972-05-08 | 1976-05-26 | Albert R D | X-ray source |
GB1505587A (en) * | 1974-05-15 | 1978-03-30 | Philips Ltd | Method of manufacturing an anode for an x-ray tube |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0181194A2 (en) * | 1984-11-08 | 1986-05-14 | Hampshire Instruments, Inc | X-ray generating system |
EP0181194A3 (en) * | 1984-11-08 | 1988-04-06 | Hampshire Instruments, Inc | X-ray generating system |
US9520262B2 (en) | 2012-06-14 | 2016-12-13 | Siemens Aktiengesellschaft | X-ray source, method for producing X-rays and use of an X-ray source emitting monochromatic X-rays |
CN103943443A (en) * | 2013-01-18 | 2014-07-23 | 通用电气公司 | X-ray source with moving anode or cathode |
CN103943443B (en) * | 2013-01-18 | 2018-07-10 | 通用电气公司 | X-ray source with movement anode or cathode |
Also Published As
Publication number | Publication date |
---|---|
DE3171782D1 (en) | 1985-09-19 |
ATE14953T1 (en) | 1985-08-15 |
EP0063190B1 (en) | 1985-08-14 |
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