X-ray tube insulator

Abstract

The invention proposes an insulator within an X-ray tube having a vacuum side and an ambient side and a feedthrough substantially coinciding with an axis of symmetry at the vacuum side and an axis of symmetry at the ambient side. The axis of symmetry at the vacuum side and the axis of symmetry at the ambient side have an angle of at least 5°, preferably 90°, with respect to each other. An X-ray source comprising such an insulator is presented as well and the present invention also extends to a medical imaging apparatus for generating X-ray images of a patient thereby using an X-ray source with such an insulator. In an embodiment, an X-ray source is provided wherein the insulator is plugged to an electrical connector at the ambient surface.

Claims

1. An asymmetric X-ray tube insulator for providing an isolation between an electrical ground potential and an electrical potential of a feedthrough in an X-ray tube, the insulator comprising: a vacuum interface configured to be contacted with a vacuum zone of the X-ray tube; an ambient interface configured to be contacted with an ambience of the X-ray tube; a feedthrough channel inside the insulator configured to receive the feedthrough for guiding the electrical potential of the feedthrough from the ambient interface to the vacuum interface, wherein the feedthrough channel extends inside the insulator from the vacuum interface to the ambient interface, wherein the vacuum interface and the ambient interface are angled with respect to each other, wherein a first axis normal to the vacuum interface is angled to a second axis normal to the ambient interface by an angle of at least 5°, wherein the vacuum interface includes a first circular part that has a diameter as viewed in a first direction, and the ambient interface includes a second circular part that has a diameter as viewed in a second direction angled to the first direction, wherein the feedthrough channel extends from the first circular part of the vacuum interface into the insulator along the first direction, wherein the feedthrough channel extends from the second circular part of the ambient interface into the insulator along the second direction, wherein the first direction is parallel to the first axis, and wherein the second direction is parallel to the second axis, and wherein the diameter of the first circular part from which the feedthrough channel extends exceeds the diameter of the second circular part from which the feedthrough channel extends by a factor of at least 2.

2. The asymmetric X-ray tube insulator according to claim 1, further comprising an electrically conductive outer surface configured to carry the ground potential, wherein the electrically conductive outer surface extends from the vacuum interface to the ambient interface.

3. The asymmetric X-ray tube insulator according to claim 2, wherein the electrically conductive outer surface extends from the vacuum interface perpendicularly towards an angled section of the insulator, and wherein the electrically conductive outer surface extends from the ambient interface perpendicularly towards the angled section of the insulator.

4. The asymmetric X-ray tube insulator according to claim 2, wherein the electrically conductive outer surface circumferentially encloses the vacuum interface, and wherein the electrically conductive outer surface circumferentially encloses the ambient interface.

5. The asymmetric X-ray tube insulator according to claim 1, wherein the first axis normal to the vacuum interface is a virtual axis of symmetry, and the second axis normal to the ambient interface is a virtual axis of symmetry.

6. The asymmetric X-ray tube insulator according to claim 1, wherein the insulator is formed of a homogeneous body of isotropic material.

7. The asymmetric X-ray tube insulator according to claim 1, wherein the vacuum interface has a virtual circular symmetry axis, wherein the vacuum interface is embodied as a pancake type of insulator interface being substantially flat and with a structured surface, wherein the ambient interface has a virtual circular symmetry axis or has virtual discrete rotational symmetry axis, and wherein the symmetry axes are angulated with respect to each other.

8. The asymmetric X-ray tube insulator according to claim 7, wherein the symmetry axis of the vacuum interface extends parallel to a direction along which the feedthrough channel extends from the vacuum interface into the insulator, and wherein the symmetry axis of the ambient interface extends parallel to a direction along which the feedthrough channel extends from the ambient interface into the insulator.

9. The asymmetric X-ray tube insulator according to claim 1, wherein the vacuum interface has a virtual circular symmetry axis, wherein the vacuum interface is embodied as a pancake type of insulator interface being substantially flat and with a structured surface, wherein a thickness of the virtual circular symmetry axis is shorter than the diameter of the vacuum interface, and wherein the insulator has a conical shape at the ambient interface.

10. The asymmetric X-ray tube insulator according to claim 1, wherein the insulator has a conical shape at the vacuum interface, wherein the ambient interface has a virtual circular symmetry axis, and wherein the ambient interface is embodied as a pancake type of insulator interface being substantially flat and with a structured surface.

11. The asymmetric X-ray tube insulator according to claim 1, wherein the feedthrough channel inside the insulator is curved and/or angled within the insulator.

12. A medical imaging apparatus for generating X-ray images of a patient, the medical imaging apparatus comprising: an X-ray source, the X-ray source including a vacuum zone and an ambience; and an asymmetric X-ray tube insulator configured to provide an isolation between an electrical ground potential and an electrical potential of a feedthrough in an X-ray tube, the insulator comprising: a vacuum interface contacted with a vacuum zone of the X-ray tube; an ambient interface contacted with an ambience of the X-ray tube; a feedthrough channel inside the insulator receiving the feedthrough for guiding the electrical potential of the feedthrough from the ambient interface to the vacuum interface, wherein the feedthrough channel extends inside the insulator from the vacuum interface to the ambient interface, wherein the vacuum interface and the ambient interface are angled with respect to each other, wherein a first axis normal to the vacuum interface is angled to a second axis normal to the ambient interface by an angle of at least 5°, wherein the vacuum interface includes a first circular part that has a diameter as viewed in a first direction, and the ambient interface includes a second circular part that has a diameter as viewed in a second direction angled to the first direction, wherein the feedthrough channel extends from the first circular part of the vacuum interface into the insulator along the first direction, wherein the feedthrough channel extends from the second circular part of the ambient interface into the insulator along the second direction, wherein the first direction is parallel to the first axis, and wherein the second direction is parallel to the second axis, and wherein the diameter of the first circular part from which the feedthrough channel extends exceeds the diameter of the second circular part from which the feedthrough channel extends by a factor of at least 2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject-matter of the invention will be explained in more detail in the following with reference to the exemplary embodiments which are illustrated in the attached figs, wherein

(2) FIG. 1 shows a cross-sectional view through a prior art insulator typically used in X-ray sources;

(3) FIG. 2 schematically shows a cross-section through an asymmetric insulator according to an exemplary embodiment of the present invention; and

(4) FIG. 3 schematically shows a medical imaging system comprising an X-ray source and an X-ray source insulator according to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(5) FIG. 1 schematically shows a cross-section through an X-ray source comprising an X-ray source insulator of the prior art. The X-ray source 100 is shown with the vacuum zone 101 with the alumina part 102. The vacuum interface is depicted in FIG. 1 by reference sign 106. Furthermore, a silicon slab 103 is comprised, which is an electrically stable interface where a small diameter suffices. Moreover, a plastic insulator 104 is comprised in the setup shown in FIG. 1. The X-ray source 100 also comprises the oil or cable interface 105, which is the interface to the ambience. As can be seen from FIG. 1, the prior art makes use of axisymmetric designs since they are simplifying manufacturing and minimizing thermal or electrical distortions. So far, the skilled persons have considered such axisymmetric and/or concentrical X-ray insulators as beneficial and sufficient since they successfully shield even under adverse conditions at the vacuum side like influencing of ionizing agents like charge carriers, UV or X-rays as well as at the ambient side under oil or flexible bulk insulators.

(6) However, the inventors of the present invention have found during their research that a different geometry of the insulator is beneficial for several different applications of X-ray sources in the future. In an embodiment, the inventors of the present invention suggest the use of angulated isotropic insulators, for example angulated alumina ceramics insulators, which represent the interface between the vacuum and the ambience. This may be applied for X-ray tubes and other vacuum electronic devices.

(7) As a non-limiting example, FIG. 2 shows a cross-section of an asymmetric X-ray tube insulator 200 for providing an isolation between an electrical ground potential 208 and an electrical potential of a feedthrough 207. The insulator comprises a vacuum interface 201 for being contacted with the vacuum zone 211 of the X-ray tube. Moreover, the ambient interface 202 is configured for being contacted with the ambience 212 of the X-ray tube. The feedthrough channel 213 extends inside the insulator and is configured for receiving the feedthrough for guiding the electrical potential of the feedthrough from the ambient interface to the vacuum interface. Electrical connectors and cables may then be applied to the feedthrough or the feedthroughs of the insulator at the vacuum side in order to bring electrical power to several different devices, like for example control devices, sensors or heating devices. As can be seen from FIG. 2, the feedthrough channel 213 extends inside the insulator 200 from the vacuum interface 201 to the ambient interface 202. The vacuum interface 201 and the ambient interface 202 are angled with respect to each other. Hence, a non-coaxial and non-axisymmetric design and geometry is provided. While taking into account the mismatch of required size between both interfaces, the insulator 200 of this embodiment is extremely flat along the symmetry axis 205 of the vacuum interface 201. In other words, the horizontal width, i.e. the axial thickness, of the insulator 200 in the shown cross-sectional view is reduced by means of the asymmetric geometry.

(8) The insulator 200 comprises also an electrically conductive outer surface 214 for carrying the ground potential 208. The electrically conductive outer surface 214 extends from the vacuum interface 201 to the ambient interface 202. The angled configuration of both interfaces 201, 202 is characterized in that the feedthrough channel 213 extends from the 201 into the insulator 200 along a first direction which is angled to a second direction along which the feedthrough channel extends from the ambient interface 202 into the isolator 200. The angle of the exemplary embodiment of FIG. 2 is 90°. However, the technical advantage of reducing the thickness of the insulator along the symmetry axis of the vacuum interface can already be achieved with angles that are at least 5°. Hence, according to other exemplary embodiments, an angulation of 10°, 15°, 20°, 30°, 45°, 50°, 60°, 70°, 80° or 85° can be used to realize this technical effect.

(9) It can also be gathered from FIG. 2 that the vacuum interface 201 has a virtual axis of symmetry 205 and the ambient interface 202 has a virtual axis of symmetry 206. In the embodiment of FIG. 2, the angle between the two symmetry axes is 90°. FIG. 2 also shows two top views 203 and 204. Top view 203 shows the top view of the ambient interface 202, whereas top view 204 shows the vacuum interface 201. The electrically conductive feedthrough 207 which runs along the feedthrough channel 213 can be seen within the cross-sectional view on the right-hand side of FIG. 2 and can also be seen in the top view 204. The vacuum zone 211 is thus brought into contact with the vacuum interface 201 whereas the ambient interface 202 is brought into contact with the ambience 212 when the insulator is applied to the X-ray tube. The angle of 90° of the setup of FIG. 2 is depicted in FIG. 2 with reference sign 210. The body 209 of insulator 200 may be out of isotropic material, for example of alumina.

(10) In an embodiment an X-ray source is provided wherein the insulator 200 is plugged to an electrical connector at the ambient surface.

(11) According to another exemplary embodiment of the present invention, FIG. 3 shows a medical imaging device 300 for generating X-ray images of a patient. It is clear to the skilled person that this is a schematic, simplified drawing. The medical imaging apparatus 300 comprises an X-ray source 302 with an asymmetric X-ray source/X-ray tube insulator 307, which is only depicted schematically and for illustrative purposes only. This C-arm 301 also comprises the X-ray detector 303 and the patient table 304. The medical imaging system 300 shown in FIG. 3 also comprises a display 305 and a control unit 306 to be used by the medical practitioner. Any of the previously mentioned asymmetric insulators of embodiments of the present invention can be applied and used within the medical imaging system 300 shown in FIG. 3.

(12) In the medical imaging device 300 the following exemplary embodiments of the insulator 307 may be used. For example, the entire insulator 307 (comprising vacuum and ambient insulator interfaces) may consist of a single homogeneous block of isotropic material, e.g. alumina. The block may be manufactured from multiple elements, which are later joined, e.g. by sintering or by gluing or other techniques. The insulator or parts of it may be manufactured by 3D printing. In one embodiment, a pancake type of insulator interface at the vacuum side (substantially flat, structured, circular symmetric) would be accompanied by another insulator interface with ambient which has a different symmetry axis (circular symmetry or discrete rotational symmetry), where both axes are angulated w.r.t. each other.

(13) Alternatively, the medical imaging device 300 comprises a pancake insulator interface at the vacuum side accompanied by an angulated conical insulator structure at the ambient side or vice versa.

(14) In another embodiment of medical imaging device 300 a pancake insulator at the vacuum side is accompanied by a substantially different pancake insulator structure at the ambient side or vice versa.

(15) It may be seen as a gist of the present invention that the insulator has a vacuum side and an ambient side and a feedthrough substantially coinciding with an axis of symmetry at the vacuum side and an axis of symmetry at the ambient side wherein the axis of symmetry at the vacuum side and at the ambient side have an angle of at least 5°, preferably 90° with respect to each other.