X-RAY TUBE HOUSING
United States Patent 3859534
A housing for an x-ray tube is described in which a tubular liner of higher tensile strength metal, such as steel, is provided on the inner surface of a housing member in order to prevent destruction of the housing member in the event a rotating anode in such tube breaks at high rotation speed. The liner can be a split sleeve of perforated sheet metal which is held in contact with the housing member by pressing a tubular shield of x-ray absorbing material, such as lead, outward to deform the shield until the liner is clamped between such shield and the inner surface of the housing.
US Patent References:
Chi-ray shield
Wappler - August 1932 - 1874672
Port structure for x-ray devices
Fengler - May 1964 - 3134903
Chi-ray shield
Wappler - August 1932 - 1874672
Port structure for x-ray devices
Fengler - May 1964 - 3134903
Application Number:
05/225739
Publication Date:
01/07/1975
Filing Date:
02/14/1972
View Patent Images:
Export Citation:
Assignee:
Picker Corporation (Cleveland, OH)
Primary Class:
Other Classes:
378/125
International Classes:
H01J35/16; H05G1/04; H01J35/00; H05G1/00; H01J35/16
Field of Search:
250/493,503,505,520,523
Primary Examiner:
Lindquist, William F.
Attorney, Agent or Firm:
Blore, Stephen W.
Claims:
I claim
1. A rotary anode x-ray tube housing apparatus comprising:
2. A housing apparatus in accordance with claim 1 in which the liner member is provided on the inner surface of the housing member beneath the shield and is of less thickness than the wall of the housing and the shield.
3. A housing apparatus in accordance with claim 2 in which the liner member is made of perforated sheet metal.
4. A housing apparatus in accordance with claim 1 in which the liner member is made of steel.
5. A housing apparatus in accordance with claim 4 in which the shield is made of lead.
6. A housing apparatus in accordance with claim 5 in which the housing member is made of aluminum.
7. A housing apparatus in accordance with claim 6 in which the window portion is made of a plastic material.
8. A housing apparatus in accordance with claim 1 in which the liner member is a split sleeve.
9. A housing apparatus in accordance with claim 8 in which the shield is a layer of lead which holds the split sleeve liner member in contact with the inner surface of the housing member.
1. A rotary anode x-ray tube housing apparatus comprising:
2. A housing apparatus in accordance with claim 1 in which the liner member is provided on the inner surface of the housing member beneath the shield and is of less thickness than the wall of the housing and the shield.
3. A housing apparatus in accordance with claim 2 in which the liner member is made of perforated sheet metal.
4. A housing apparatus in accordance with claim 1 in which the liner member is made of steel.
5. A housing apparatus in accordance with claim 4 in which the shield is made of lead.
6. A housing apparatus in accordance with claim 5 in which the housing member is made of aluminum.
7. A housing apparatus in accordance with claim 6 in which the window portion is made of a plastic material.
8. A housing apparatus in accordance with claim 1 in which the liner member is a split sleeve.
9. A housing apparatus in accordance with claim 8 in which the shield is a layer of lead which holds the split sleeve liner member in contact with the inner surface of the housing member.
Description:
BACKGROUND OF THE INVENTION
The subject matter of the present invention relates generally to x-ray tube housings and in particular to a housing apparatus containing a tubular liner of metal of a higher tensile strength than the material of the housing member and the x-ray absorbing shield which may be provided as an inner layer over such liner.
The present housing apparatus is especially useful for containing rotating anode x-ray tubes since it prevents destruction of the housing member in the event that the rotating anode breaks at high rotation speed so pieces fly off and shatter the x-ray tube. Previous x-ray tube housings made of aluminum or other lightweight, low tensile strength material and not employing the liner member of the present invention, have broken when the x-ray tube contained in such housings shatters which can cause injury to patients and operating personnel. This is especially hazardous for rotating anode x-ray tubes since, when the anode breaks, it is thrown outward against the housing with great force due to centrifugal force.
It is, therefore, one object of the present invention to provide an improved x-ray tube housing of substantially unbreakable construction which is lightweight and of relatively low cost to manufacture.
Another object of the invention is to provide such a housing which employs a tubular liner of metal of higher tensile strength than the material of the outer housing member and the x-ray absorbing shield contained therein so that such housing member will not be destroyed in the event the x-ray tube breaks.
A further object of the invention is to provide such a housing in which the liner member is in the form of a split sleeve which is held in contact with the inner surface of the housing member by a tubular shield.
Still another object of the invention is to provide an x-ray tube housing for a rotating anode x-ray tube which is not broken when the rotating anode target shatters and pieces fly off against the inside of the housing .
BRIEF DESCRIPTION OF THE DRAWING
Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment thereof and from the attached drawings of which:
FIG. 1 is an oblique plan view of the x-ray tube housing of the present invention;
FIG. 2 is a plan view taken along the line 2--2 of FIG. 1 with parts broken away to show the x-ray tube mounted within such housing;
FIG. 3 is a vertical section view taken along the line 3--3 of FIG. 2 showing the x-ray tube in phantom lines;
FIG. 4 is an oblique section view of one embodiment of the liner member employed in the housing of FIGS. 1 to 3.
DESCRIPTION OF PREFERRED EMBODIMENT
As shown in FIGS. 1 and 2, an x-ray tube housing 10 made in accordance with the present invention includes an intermediate housing portion 12 attached between a pair of end portions 14 and 16 by releasable fluid tight seals to contain an insulating fluid 17 (liquid or gas) within the housing while enabling replacement of the x-ray tube therein. The end portions 14 and 16 have electrical cable connectors 18 and 20, respectively, provided therein for supplying high voltage and current to an x-ray tube 22 supported within the intermediate housing portion 12. The x-ray tube 22 may have a rotating anode 24 and a fixed filament cathode 26 provided within an evacuated glass envelope 28 so that electrons 30 emitted by such filament strike a target portion 31 of the anode and cause x-rays 32 to be emitted therefrom. The target anode 24 is rotated in a conventional manner by a rotor and bearing member 34 provided within the envelope 28 in response to an electromagnetic field produced by field windings (not shown) on the exterior of the envelope. The intermediate portion 12 of the housing includes an x-ray transparent window 36 of polycarbonate resin sold under the trademark "Lexan" or other high impact plastic material provided over an opening in a cylindrical housing member 38 of cast aluminum or other lightweight material. The window 36 is in alignment with the focal spot on the target 31 of anode 24 from which the x-rays 32 are emitted so that such x-rays pass through such window to the exterior of the housing.
As shown in FIGS. 3 and 4, a tubular shield 40 of lead or other x-ray absorbing material is provided within the housing member 38 and covers the inner surface of such housing member except for an opening in alignment with the window 36 to prevent x-rays from being transmitted through the housing member 38 in any areas other than such window. The lead shield 40 may be formed by several layers of lead each on the order of about one-sixteenth inch thick to provide a laminated shield of desired thickness for absorbing x-rays of maximum intensity depending upon the voltage and current of the x-ray tube.
A tubular liner member 42 of steel or other high tensile strength metal is provided within the housing member 38 between the shield 40 and the inner surface of the housing member to provide such housing with greater impact strength. The metal of the liner member 42 has a higher tensile strength than the material of the housing member 38 or the shield 40. For example, the tensile strength of a low carbon steel liner 42 is about 80,000 lbs. per square inch, while an aluminum housing member 38 is about 31,000 lbs. per square inch and a lead shield member 40 is about 6,800 lbs. per square inch.
As shown in FIG. 4, the liner member 42 may be a split sleeve of sheet metal having a longitudinal gap 44 between the ends of such sleeve. The sleeve is rolled into the desired shape and inserted into the cylindrical housing member 38. The tubular lead shield 40 is then inserted inside the liner 42 and pressed outwardly by a roller, pneumatic bag, or other means to deform the lead shield outwardly and thereby urge the liner 42 into intimate contact with the inner surface of the housing member 38. As a result, the liner 42 is clamped in place between the shield and the housing member. The liner member 42 may be provided with a plurality of small holes about 0.3125 inch in diameter having seven-sixteenths inch spaced centers, to reduce the weight of the liner without greatly effecting its strength. It should be noted that a larger opening 48 is provided in the liner 42 and positioned in alignment with the window 36 to enable the x-rays to be transmitted through such liner without attenuation.
Any suitable high tensile strength metal can be employed for the liner 42 including nickel, titanium, molybdenum, stainless steel and other alloys, including low carbon steels. Suitable low carbon steels typically have a chemical composition by weight of 0.05 to 0.10 percent carbon, 0.25 to 0.50 percent manganese, 0.04 percent maximum phosphorous, 0.5 percent maximum sulphur and the balance iron. In one embodiment, the lead shield 40 and the aluminum housing 38 had wall thicknesses of 0.125 inch while the steel liner 42 was about one-fourth that thickness or about 0.03125 inch.
It is possible to make the liner 42 out of a unperforated cylinder of steel rather than the split sleeve shown in FIG. 4, but this would require the outer diameter of the shield to exactly match the inner diameter of the housing member 38. The advantage of the split sleeve embodiment of the liner 42 is that its diameter can be changed to automatically compensate for manufacturing tolerances in the inner diameter of the housing member 38. Also, while the liner 42 is shown only provided on the inner surface of the intermediate portion 12 of the housing surrounding the x-ray tube anode, it is also possible to extend the liner and the lead shield into the end portions 14 and 16 so that they extend throughout the entire length of the housing for maximum safety.
It will be obvious to those having ordinary skill in the art that many changes may be made in the above-described preferred embodiment of the present invention without departing from the spirit of the invention. Therefore, the scope of the invention should only be determined by the following claims.
The subject matter of the present invention relates generally to x-ray tube housings and in particular to a housing apparatus containing a tubular liner of metal of a higher tensile strength than the material of the housing member and the x-ray absorbing shield which may be provided as an inner layer over such liner.
The present housing apparatus is especially useful for containing rotating anode x-ray tubes since it prevents destruction of the housing member in the event that the rotating anode breaks at high rotation speed so pieces fly off and shatter the x-ray tube. Previous x-ray tube housings made of aluminum or other lightweight, low tensile strength material and not employing the liner member of the present invention, have broken when the x-ray tube contained in such housings shatters which can cause injury to patients and operating personnel. This is especially hazardous for rotating anode x-ray tubes since, when the anode breaks, it is thrown outward against the housing with great force due to centrifugal force.
It is, therefore, one object of the present invention to provide an improved x-ray tube housing of substantially unbreakable construction which is lightweight and of relatively low cost to manufacture.
Another object of the invention is to provide such a housing which employs a tubular liner of metal of higher tensile strength than the material of the outer housing member and the x-ray absorbing shield contained therein so that such housing member will not be destroyed in the event the x-ray tube breaks.
A further object of the invention is to provide such a housing in which the liner member is in the form of a split sleeve which is held in contact with the inner surface of the housing member by a tubular shield.
Still another object of the invention is to provide an x-ray tube housing for a rotating anode x-ray tube which is not broken when the rotating anode target shatters and pieces fly off against the inside of the housing .
BRIEF DESCRIPTION OF THE DRAWING
Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment thereof and from the attached drawings of which:
FIG. 1 is an oblique plan view of the x-ray tube housing of the present invention;
FIG. 2 is a plan view taken along the line 2--2 of FIG. 1 with parts broken away to show the x-ray tube mounted within such housing;
FIG. 3 is a vertical section view taken along the line 3--3 of FIG. 2 showing the x-ray tube in phantom lines;
FIG. 4 is an oblique section view of one embodiment of the liner member employed in the housing of FIGS. 1 to 3.
DESCRIPTION OF PREFERRED EMBODIMENT
As shown in FIGS. 1 and 2, an x-ray tube housing 10 made in accordance with the present invention includes an intermediate housing portion 12 attached between a pair of end portions 14 and 16 by releasable fluid tight seals to contain an insulating fluid 17 (liquid or gas) within the housing while enabling replacement of the x-ray tube therein. The end portions 14 and 16 have electrical cable connectors 18 and 20, respectively, provided therein for supplying high voltage and current to an x-ray tube 22 supported within the intermediate housing portion 12. The x-ray tube 22 may have a rotating anode 24 and a fixed filament cathode 26 provided within an evacuated glass envelope 28 so that electrons 30 emitted by such filament strike a target portion 31 of the anode and cause x-rays 32 to be emitted therefrom. The target anode 24 is rotated in a conventional manner by a rotor and bearing member 34 provided within the envelope 28 in response to an electromagnetic field produced by field windings (not shown) on the exterior of the envelope. The intermediate portion 12 of the housing includes an x-ray transparent window 36 of polycarbonate resin sold under the trademark "Lexan" or other high impact plastic material provided over an opening in a cylindrical housing member 38 of cast aluminum or other lightweight material. The window 36 is in alignment with the focal spot on the target 31 of anode 24 from which the x-rays 32 are emitted so that such x-rays pass through such window to the exterior of the housing.
As shown in FIGS. 3 and 4, a tubular shield 40 of lead or other x-ray absorbing material is provided within the housing member 38 and covers the inner surface of such housing member except for an opening in alignment with the window 36 to prevent x-rays from being transmitted through the housing member 38 in any areas other than such window. The lead shield 40 may be formed by several layers of lead each on the order of about one-sixteenth inch thick to provide a laminated shield of desired thickness for absorbing x-rays of maximum intensity depending upon the voltage and current of the x-ray tube.
A tubular liner member 42 of steel or other high tensile strength metal is provided within the housing member 38 between the shield 40 and the inner surface of the housing member to provide such housing with greater impact strength. The metal of the liner member 42 has a higher tensile strength than the material of the housing member 38 or the shield 40. For example, the tensile strength of a low carbon steel liner 42 is about 80,000 lbs. per square inch, while an aluminum housing member 38 is about 31,000 lbs. per square inch and a lead shield member 40 is about 6,800 lbs. per square inch.
As shown in FIG. 4, the liner member 42 may be a split sleeve of sheet metal having a longitudinal gap 44 between the ends of such sleeve. The sleeve is rolled into the desired shape and inserted into the cylindrical housing member 38. The tubular lead shield 40 is then inserted inside the liner 42 and pressed outwardly by a roller, pneumatic bag, or other means to deform the lead shield outwardly and thereby urge the liner 42 into intimate contact with the inner surface of the housing member 38. As a result, the liner 42 is clamped in place between the shield and the housing member. The liner member 42 may be provided with a plurality of small holes about 0.3125 inch in diameter having seven-sixteenths inch spaced centers, to reduce the weight of the liner without greatly effecting its strength. It should be noted that a larger opening 48 is provided in the liner 42 and positioned in alignment with the window 36 to enable the x-rays to be transmitted through such liner without attenuation.
Any suitable high tensile strength metal can be employed for the liner 42 including nickel, titanium, molybdenum, stainless steel and other alloys, including low carbon steels. Suitable low carbon steels typically have a chemical composition by weight of 0.05 to 0.10 percent carbon, 0.25 to 0.50 percent manganese, 0.04 percent maximum phosphorous, 0.5 percent maximum sulphur and the balance iron. In one embodiment, the lead shield 40 and the aluminum housing 38 had wall thicknesses of 0.125 inch while the steel liner 42 was about one-fourth that thickness or about 0.03125 inch.
It is possible to make the liner 42 out of a unperforated cylinder of steel rather than the split sleeve shown in FIG. 4, but this would require the outer diameter of the shield to exactly match the inner diameter of the housing member 38. The advantage of the split sleeve embodiment of the liner 42 is that its diameter can be changed to automatically compensate for manufacturing tolerances in the inner diameter of the housing member 38. Also, while the liner 42 is shown only provided on the inner surface of the intermediate portion 12 of the housing surrounding the x-ray tube anode, it is also possible to extend the liner and the lead shield into the end portions 14 and 16 so that they extend throughout the entire length of the housing for maximum safety.
It will be obvious to those having ordinary skill in the art that many changes may be made in the above-described preferred embodiment of the present invention without departing from the spirit of the invention. Therefore, the scope of the invention should only be determined by the following claims.