JPH0963522A - X-ray source movement compensation mechanism for x-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a position of an X-ray source in operation, by equipping a support part supporting a positive electrode with a means capable of controlling expansions/contractions in the opposite direction to the moving direction of the X-ray source due to thermal expansions of a positive electrode member. SOLUTION: An X-ray tube 4 is constituted by disposing a negative electrode member and a rotating positive electrode target 10 so as to stand opposite to each other in a vacuum airtight enclosure 1. An end part 16 of the X-ray tube 4 which supports the positive electrode target 10 via a rotating shaft 12 is fixed to a tube container 6 via a positive electrode supporting part 14. A positive electrode member comprizing the positive electrode target 10, the rotating shaft 12 and the like expands due to heat generated when thermal electrons collide against an X-ray source 8 and cause X rays 9 to be radiated, resulting in a longitudinal position change of the X-ray source 8 occurring. The positive electrode supporting part 14 being composed of a thermally expanding support body 29 of a cylindrical shape which is made of a metal or synthetic resin such as 6 epoxy, heater wire 28 being embeded therewithin, an electric current being supplied thereto from a controller 30, a longitudinal expansion of the thermally expanding support body 29, which is caused by heat generated by the current, cancels the position change of the X-ray source 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray tube apparatus for radiating X-rays to a diagnostic region of a subject in, for example, an X-ray CT apparatus, and particularly to an X-ray source generated by thermal expansion of an anode member in the X-ray tube. The present invention relates to an X-ray source movement amount compensating mechanism of an X-ray tube device capable of canceling the movement amount of the X-ray and maintaining the position of the X-ray source during operation at a constant position.

[0002]

2. Description of the Related Art In a conventional X-ray tube device of this type, as shown in FIG. 9, a cathode member 2 and an anode member 3 are disposed inside an envelope 1 so as to face each other. And an X-ray tube 4 enclosing the cathode member 2 and the anode member 3 in a vacuum-tight manner, and an insulating oil 5 for cooling the X-ray tube 4 and performing high-voltage insulation around the X-ray tube 4. In addition, the tube container 6 enclosing the entire X-ray tube 4 and the anode support portion 14 for supporting the end portion of the anode member 3 of the X-ray tube 4 on the inner wall of the tube container 6 are provided. When a high voltage is applied between the cathode member 2 and the anode member 3 and the thermoelectrons 7 emitted from the cathode member 2 collide with the anode member 3, the X-ray source 8 of the anode member 3 emits X-rays 9. It was like this.

In particular, FIG. 9 shows a rotary anode type X-ray tube apparatus, in which an anode member 3 is arranged to face the cathode member 2, and a rotatable anode target 10 and a central portion of the anode target 10 are provided. A rotor 11 for supporting the rotor, a rotary shaft 12 provided coaxially inside the rotor 11, and a fixed portion for rotatably supporting the rotary shaft 12 via a bearing 13 and being fixed to the anode support portion 14. 15 and. The rear end of the fixed portion 15 of the anode member 3 is fixed to the rear end of the anode support portion 14 via a support end plate 16 and a fixing screw 17. The support of the X-ray tube 4 on the side of the cathode member 2 is
The cathode supporting portion 18 made of an insulating material is provided on the outer diameter portion of the tip portion of the envelope 1, and is fixedly coupled to the inner wall surface of the tube container 6. The anode target 10 of the anode member 3 is composed of a core 19A and a stator coil 19B provided on the inner peripheral surface of the intermediate portion or the front end portion of the anode supporting portion 14 slightly outside the outer peripheral surface of the rotor 11. It's a 19
Rotor 1 rotated by the rotational force generated by the principle of
It is adapted to be rotated by the rotation of 1.

In order to emit X-rays in such an X-ray tube device, the anode target 1 of the cathode member 2 and the anode member 3 is used.
When a high voltage of 100 kV is applied between 0 and 0, the thermoelectrons 7 emitted from the cathode member 2 generate the X-ray source 8 of the anode target 10.
The X-ray 9 is radiated to the outside by colliding with (a focal source on which the thermoelectrons 7 are focused).

However, in such a conventional X-ray tube device, when the X-ray tube 4 radiates X-rays 9, thermoelectrons 7 emitted from the cathode member 2 are directed to the X-ray source 8 of the anode target 10. Due to the collision, the anode target 10 was heated to about 1000 ° C., and the temperature of each part of the anode member 3 was raised, and sometimes reached several hundred ° C. At this time, the anode target 10 and the rotor 11, the rotating shaft 12, the bearing 13, and the fixed portion 15 that constitute the anode member 3 are heated, and the thermal expansion causes the support end plate 16 of the anode support portion 14 as a base point to make the anode target 10 Was moved to the cathode member 2 side. That is, the X-ray source 8 on the anode target 10 approaches the cathode member 2 side, and the amount of movement thereof may reach about 400 μm before and after the load is applied. From this, the position of the X-ray radiation with respect to the radiation center of the X-ray 9 from the tube container 6 in the operation process of the X-ray tube device was displaced, and the dose distribution of the X-ray irradiation to the subject was fluctuated. Therefore, the image quality of the X-ray image collected by the X-ray detector (not shown) arranged opposite to the X-ray tube device with the subject table (not shown) interposed therebetween deteriorates.

As a prior invention for reducing the movement amount of the X-ray source, there is one disclosed in Japanese Patent Laid-Open No. 07-130310. The present invention relates to an improvement in an X-ray tube and a mounting member thereof, which can be achieved by appropriately selecting the thermal expansion coefficients of a member forming an anode of the X-ray tube and an anode supporting member of a tube container. It has a structure that offsets the movement of the X-ray source.

[0007]

According to the result of the simulation and the experiment using the conventional X-ray tube apparatus, the movement of the X-ray source of the X-ray tube apparatus is caused by the movement of each member constituting the X-ray tube apparatus. The direction of movement and the amount of movement are determined by the temperature distribution.
When the X-ray tube device is cold, the amount of movement of the X-ray source rapidly increases immediately after the start of diagnosis. The thermal expansion of the anode member is relatively quick because it directly receives the heat energy due to the negative applied voltage, but the thermal expansion of the anode support part is due to the heat radiation from the anode target, the heat radiation from the envelope, and the anode member. It is due to the heat released due to the heat conduction, etc., so the response of the temperature change is poor, and the movement of the X-ray source due to the thermal expansion of the anode member occurs transiently, which is compensated by the thermal expansion of the anode support part. There was a problem that I could not cut it.

Therefore, the present invention copes with such a problem and cancels the movement amount of the X-ray source caused by the thermal expansion of the anode member in the X-ray tube, which occurs abruptly immediately after the diagnosis is started, and the diagnosis operation is performed. It is an object of the present invention to provide an X-ray source movement amount compensating mechanism for an X-ray tube device that can maintain the position of the X-ray source at a fixed position.

[0009]

The object of the present invention is achieved by the following means. In the X-ray source movement amount compensating mechanism of the X-ray tube device of the present invention, a cathode member and an anode member are disposed inside an envelope so as to face each other, and the inside of the envelope is vacuum-tightly held to prevent the cathode member. And an X-ray tube enclosing the anode member and the X-ray tube.
A container for accommodating insulating oil for cooling the X-ray tube and performing high-voltage insulation around the X-ray tube, and enclosing the entire X-ray tube, and supporting an end portion of the anode member of the X-ray tube. And an anode supporting part fixed to the inner wall of the tube container,
An X-ray tube that emits X-rays from an X-ray source of the anode member by applying a high voltage between a cathode member and an anode member of the X-ray tube and causing thermoelectrons emitted from the cathode member to collide with the anode member. In the apparatus, X due to thermal expansion of the anode member generated by applying a high voltage between the cathode member and the anode member of the X-ray tube.
The anode supporting the anode member is provided with an X-ray source movement amount canceling means that expands and contracts in a direction opposite to the moving direction of the X-ray source in accordance with the movement amount of the X-ray source and can control the expansion and contraction amount. It is provided on the support portion (Claim 1). In this configuration, the movement amount canceling means provided in the anode support portion expands and contracts the anode support portion in a direction opposite to the movement direction of the X-ray source due to thermal expansion of the anode member, and the X-ray source due to thermal expansion of the anode member. It works to offset the movement amount of. As a result, the position of the X-ray source in the operating X-ray tube can be maintained at a fixed position.

In the X-ray source movement amount compensating mechanism of the X-ray tube apparatus of the present invention, further, the X-ray source movement amount canceling means has one end connected to an anode support for fixing and supporting the anode member, and the other end. Is fixed to the inner wall of the tube container, has a cylindrical thermal expansion support, a heater mounted on the thermal expansion support to heat the thermal expansion support, and detects the temperature of the thermal expansion support. And a heater controller for controlling heating of the thermal expansion support by the heater so that the expansion of the thermal expansion support can offset the movement amount of the X-ray source. ). In this structure, the movement amount offsetting means is provided with the thermal expansion support, the heater and the heater.
It consists of three elements of the tacon controller, and the thermal expansion support is heated or cooled by the heater under the control of the heater controller to expand and contract to offset the movement amount of the X-ray source.

In the X-ray source movement amount compensating mechanism of the X-ray tube apparatus according to the present invention, the heater controller further comprises a temperature sensor section for detecting the temperature of the thermal expansion support, and movement of the X-ray source. A calculation processing unit for obtaining the temperature at which the thermal expansion support should rise or fall based on the amount, and a heating current is passed through the heater to increase the temperature of the thermal expansion support, and the thermal expansion support is heated. And a heater current controller for controlling the heating current of the heater when the temperature of the heater is lowered (claim 3). In this configuration, the heater controller includes a temperature sensor section, a calculation processing section, and a heater current control section. Based on the temperature of the thermal expansion support, the current to be passed to the heater is obtained and the data is calculated. The amount of movement of the X-ray source is offset by controlling the heater current according to the data.

Further, in the X-ray source movement amount compensating mechanism of the X-ray tube device of the present invention, the X-ray source movement amount canceling means inserts an elastic layer between the thermal expansion support and the heater. (Claim 4). In this configuration, the thermal expansion support and the heat
Since the elastic body is inserted between the heaters, local heating by the heater is eliminated, and local thermal deformation of the thermal expansion support is prevented.

In the X-ray source movement amount compensating mechanism of the X-ray tube device of the present invention, the heater is a sheet-shaped heater (Claim 5). With this configuration, the entire thermal expansion support can be uniformly heated, and the compensation accuracy of the X-ray source movement amount can be improved.

The X-ray source movement amount compensating mechanism of the X-ray tube apparatus of the present invention further comprises X-ray source movement amount detecting means for detecting the movement amount of the X-ray source due to thermal expansion of the anode member of the X-ray tube. (Claim 6). In this configuration, X-ray source movement amount detection means is added so that the movement amount of the X-ray source can be measured.

In the X-ray source movement amount compensating mechanism of the X-ray tube device according to the present invention, the X-ray source movement amount detecting means is arranged to face the X-ray tube device with the object table interposed therebetween. X
An X-ray transmission limiting member having a slit narrower than the X-ray source width is provided in a part of the X-ray detector, and an X-ray source movement amount detector for detecting a change in dose distribution of X-rays incident through the slit. Is provided (Claim 7). In this configuration, the X-ray source movement amount detection means utilizes that the X-ray dose distribution transmitted through the slit changes according to the movement amount of the X-ray source, and is composed of a slit and an X-ray dosimeter.

In the X-ray source movement amount compensating mechanism of the X-ray tube apparatus of the present invention, the movement amount of the X-ray source due to thermal expansion of the anode member of the X-ray tube is further calculated based on the amount of heat accumulated in the anode of the X-ray tube. (Claim 8). In this configuration, by utilizing the fact that there is a fixed relationship between the amount of movement of the X-ray source and the amount of heat accumulated in the anode of the X-ray tube, the amount of movement of the X-ray source is not actually measured, but instead the X-ray tube The amount of heat stored in the anode can be used.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an enlarged sectional view showing a main part of an X-ray source movement amount compensation mechanism of an X-ray tube device according to the present invention. First, since the overall configuration of the X-ray tube device according to the present invention is the same as that of the conventional example shown in FIG. 9, its structure will be described below with reference to FIG. That is, the X-ray tube device according to the present invention comprises an X-ray tube 4 and a tube container 6, as shown in FIG.

The X-ray tube 4 generates an X-ray tube and emits it to the outside, and the cathode member 2 and the anode member 3 are provided inside the envelope 1.
Are opposed to each other, the inside of the envelope 1 is kept vacuum-tight, and the cathode member 2 and the anode member 3 are enclosed. A negative potential is applied to the cathode member 2 from an external high voltage power source (not shown), and a positive potential is applied to the anode member 3. When a high voltage is applied between the cathode member 2 and the anode member 3, the thermoelectrons 7 emitted from the cathode member 2
Collide with the anode target 10 of the anode member 3 to emit X-rays 9 from the X-ray source of the anode member 3.

In particular, FIG. 9 shows a rotary anode type X-ray tube device, in which the anode member 3 is a rotatable anode target 10 arranged facing the cathode member 2 and a central portion of the anode target 10. A rotor 11 that axially supports the rotor 11, a rotary shaft 12 that is provided coaxially inside the rotor 11, and a fixing portion 15 that rotatably supports the rotary shaft 12 via a bearing 13 and that is fixed to the anode support portion 14. It consists of and. In addition,
The rear end of the fixed portion 15 of the anode member 3 is fixed to the rear end of the anode support portion 14 via a support end plate 16 and a fixing screw 17. Further, the support of the X-ray tube 4 on the cathode member 2 side is connected and fixed to the inner wall surface of the tube container 6 by the cathode support portion 18 made of an insulating material provided on the outer diameter portion of the tip portion of the envelope 1. There is. The anode target 10 of the anode member 3 is composed of a core 19A and a stator coil 19B provided on the inner peripheral surface of the intermediate portion or the front end portion of the anode supporting portion 14 slightly outside the outer peripheral surface of the rotor 11. -Ta 19
Rotor 1 rotated by the rotational force generated by the principle of
It is adapted to be rotated by the rotation of 1.

The tube container 6 serves as a casing of the entire X-ray tube apparatus, and contains the insulating oil 5 for cooling the X-ray tube 4 and performing high-voltage insulation around the X-ray tube 4, and X-ray tube 4
It consists of the whole of.

In order to emit X-rays in the X-ray tube device constructed as described above, a high voltage of several hundred tens kV is applied between the cathode member 2 and the anode target 10 of the anode member 3, and the cathode member is The thermoelectrons 7 emitted from 2 are anode targets 10
The X-ray 9 is radiated to the outside by colliding with the X-ray source 8.

Here, in the present invention, an X-ray source movement amount detecting means and a movement amount canceling means are provided for the X-ray tube device. The X-ray source movement amount detecting means is the X-ray tube 4.
The amount of movement of the X-ray source 8 due to the thermal expansion of the anode member 3 caused by applying a high voltage between the cathode member 2 and the anode member 3 is detected. For example, X shown in FIGS.
In the X-ray CT apparatus, a part of an X-ray detector 23 is arranged to face the X-ray tube device 21 configured as described above with a subject table (not shown) on which the subject 22 is placed. , An X-ray transmission limiting member 25 having a slit 24 (see FIG. 3) narrower than the line width 20 of the X-ray 9, and detecting the change in the dose distribution of the X-ray 9 incident through the slit 24. The source movement amount detector 26 is provided.

More specifically, in the embodiment shown in FIG. 2, X-rays 9 are radially generated from the X-ray source 8 of the anode target 10 in the X-ray tube device 21, and the X-rays 9 are covered by the collimator 27. Narrow the line width passing through the specimen 22,
After that, a tomographic image is constructed from the X-ray dose incident on the X-ray detector 23. In this embodiment, an X-ray source movement amount detector 26 is provided at one end of the X-ray detector 23,
As shown in FIG. 3, an X-ray transmission limiting member 25 having a slit 24 narrower than the line width 20 of the X-ray 9 is provided on the X-ray incident side of the X-ray source movement amount detector 26. X-ray tube device 2
3, the X-ray 9 emitted from the X-ray source 8 passes through the aperture of the collimator 27 and then the slit 24 of the X-ray transmission limiting member 25 in FIG. It is incident on the movement amount detector 26. At this time,
The X-ray 9 has substantially the entire width of the line width 20 extending over the slit 24, and the dose distribution of the X-ray detected by the X-ray source movement amount detector 26 shows a predetermined value. After that, it is assumed that the anode member 3 shown in FIG. 9 thermally expands and the anode target 10 moves to the cathode member 2 side, and in FIG.
Suppose you have moved to the position indicated by. Then, this X-ray source 8A
The X-ray 9A emitted from passes through the diaphragm of the collimator 27, travels along the path indicated by the broken line, passes through the slit 24, and enters the X-ray source movement amount detector 26. At this time, the X-ray 9A has only a part of the line width 20 of the X-ray that is applied to the slit 24, and the dose distribution of the X-ray detected by the X-ray source movement amount detector 26 changes. Then, the relationship between the change in the X-ray dose distribution detected in this way and the amount of movement of the X-ray source 8 at that time is grasped in advance, so that the X-ray source movement amount detector 26 detects it. By knowing the change in the X-ray dose distribution, the amount of movement of the X-ray source 8 can be known.

The movement amount offsetting means is the anode member 3 described above.
The X-ray source 8 due to the thermal expansion of the anode member 3
The expansion and contraction of the anode member 3 of the X-ray tube 4 on the inner wall of the tube container 6, as shown in FIG. 14
Is provided with a thermal expansion support 29 extending in the tube axis direction of the X-ray tube 4 and having the heater wire 28 embedded therein, and the heater wire 28 is energized to adjust the expansion and contraction of the thermal expansion support 29. A heater controller 30 for controlling is provided.

More specifically, the thermal expansion support 2
The heater wire 28 is formed by embedding a spirally wound heater wire 28 in a spacer formed of metal or synthetic resin in a cylindrical shape, and energizing the heater wire 28 by a heater controller 30. Generate heat to heat the spacer, and the entire thermal expansion support 29 extends in a direction away from the cathode member 2 in the tube axis direction of the X-ray tube 4. Now, for example, if the spacer material is made of epoxy resin and has a cylindrical shape with a length of 100 mm, the linear expansion coefficient of the epoxy resin is about 7 × 10 ⁻⁵ , and therefore the temperature of the spacer in the heater wire 28 is about 60. By heating so that the temperature rises by 0 ° C., the thermal expansion support 29 is moved to about 4
It extends by about 00 μm. In this way, the thermal expansion support 29 extends in the tube axis direction of the X-ray tube 4, whereby the anode support 1
Since 4 extends away from the cathode member 2, the anode target 10 can be moved in the direction opposite to the moving direction of the X-ray source 8 via the support end plate 16 and the fixing screw 17. This offsets the movement amount of the X-ray source 8,
The position of the X-ray source 8 during operation can be maintained at a fixed position.

As described above, the entire thermal expansion support 29 of the anode support portion 14 extends in the direction away from the cathode member 2 in the tube axis direction of the X-ray tube 4, so that the X-ray tube 4 is moved. Although a force to move the whole inside the tube container 6 acts, since the central portion 1a of the envelope 1 is made of metal and the base portion 1b is formed in a flat plate shape, both ends thereof are fixed. The flat plate-shaped base portion 1b elastically deforms with a small stress with respect to the force or pressure applied to the member in the vertical direction,
The anode member 3 side of the X-ray tube 4 is movable. In the actual X-ray tube 4, the anode member 3 side is already deformed to the extent of about 500 μm toward the cathode member 2 only by evacuating the inside of the envelope 1. Therefore, the expansion of the thermal expansion support 29 causes the X-ray tube 4 side of the anode member 3 to move in the direction opposite to the cathode member 2. When the envelope 1 is entirely made of glass, or when the base member 1b is formed in a cup shape to increase the rigidity, the X-ray tube 4 is made of a material such as rubber having a small elastic coefficient. It suffices to support the tube container 6.

Further, in order to control the expansion and contraction of the anode support portion 14, it is necessary to know the temperature of the anode support portion 14 (the thermal expansion support 29 in FIG. 1) and to grasp the thermal expansion state. . Therefore, for example, as shown in FIG.
A temperature sensor 31 such as a thermocouple is provided on the side surface or in the vicinity of the thermal expansion support 29 of the anode support portion 14, and a signal from the temperature sensor 31 is taken in to measure the temperature with a thermometer (not shown). It has become.

Next, the movement amount of the X-ray source 8 of the anode member 3 caused by the thermal expansion of the anode member 3 in the X-ray tube 4 by the X-ray source movement amount detecting means and the movement amount canceling means as described above. The operation of canceling the will be described with reference to the flowchart of FIG. First, in FIG. 3, while driving the X-ray tube device 21 to emit X-rays 9 and detect the X-rays transmitted through the subject 22 with the X-ray detector 23, the X-ray transmission limiting member 25
The movement amount of the X-ray source 8 is detected by the X-ray source movement amount detecting means including the X-ray source movement amount detector 26 and the X-ray source movement amount detector 26 (step A). At this time, the slit 2 indicates that the X-ray source 8 has moved to the position 8A due to the thermal expansion of the anode member 3 due to the radiation operation of X-rays.
The X-rays 9 and 9A that are incident through the laser beam 4 are detected by the X-ray source movement amount detector 26, and the movement amount is detected by the change in the dose distribution.

Next, in FIG. 1, the temperature of the thermal expansion support 29 is detected (step B). That is, the temperature sensors 31 and 31A detect the temperature of the thermal expansion support 29 and the insulating oil 5 around it. At this time, the thermal expansion support 2
The relationship between the temperature of 9 and the expansion of the thermal expansion support 29 at that temperature is approximately proportional as shown in the graph of FIG. Thus, by knowing the current temperature of the thermal expansion support 29, it is possible to know the length of the thermal expansion support 29 at that time, and how much temperature is required to further extend the thermal expansion support 29. You can know what to raise. The measurement signals from the temperature sensors 31 and 31A are converted into temperature values by the heater controller 30 or the console.

Next, the X-ray source 8 detected in step A above
The amount of expansion of the thermal expansion support 29 is determined according to the amount of movement (step C). That is, since the current temperature of the thermal expansion support 29 is detected in step B and the length thereof is known, how much further the thermal expansion support 29 should be extended to cancel the movement amount of the X-ray source 8. Calculate whether it is good. This calculation may be performed by placing a calculation processing unit on the heater controller 30 or the console.

Next, the thermal expansion support 29 is expanded / contracted by the movement offsetting means (step D). That is, since the expansion amount of the thermal expansion support 29 is determined in step C above,
For example, using the graph shown in FIG. 5, the thermal expansion support 2
9, the temperature difference Δ of the thermal expansion support 29 corresponding to the expansion amount Δl of 9
The heater controller 30 shown in FIG. 1 is controlled so as to obtain t and generate this Δt. As a result, the current required to generate the temperature difference Δt is supplied from the heater controller 30 to the heater wire 28, and the heater wire 2 is heated.
The heat generation of 8 heats the thermal expansion support 29. Then, the entire thermal expansion support 29 extends in a direction away from the cathode member 2 in the tube axis direction of the X-ray tube 4. At this time, the anode target 10 can be moved in the direction opposite to the moving direction of the X-ray source 8 via the support end plate 16 and the fixing screw 17 shown in FIG. The amount of movement can be offset to maintain the position of the operating X-ray source at a constant position. Hereinafter, the above operation may be repeated.

In the above operation, step B,
The temperature sensor 31, 31A functioning in C and the movement amount calculation processing unit of the X-ray source 8 have been described as independent elements that constitute movement amount canceling means, but the heater controller 3
It is also possible to control the heater controller 30 to control the heater controller 30 by including steps 0 to 0 together.

FIG. 6 is a graph for explaining another example of the method of knowing the movement amount of the X-ray source 8, and the movement amount of the X-ray source corresponding to the heat input state of the anode member 3 is grasped in advance. It shows a method. The graph of FIG. 6 shows the relationship between the passage of time and the accumulated heat capacity of the anode and the movement amount of the X-ray source. When the temperature of the anode member 3 rises with the load input of the X-ray tube 4 and the X-ray source 8 starts to move rapidly, and the heat capacity of the anode member 3 reaches an equilibrium state, the movement amount of the X-ray source 8 also becomes equilibrium state. Become. During cooling, the temperature of the anode member 3 in a high temperature rapidly decreases due to radiation, and the amount of thermal expansion also decreases, so that the amount of movement of the X-ray source 8 also decreases. In FIG. 6, when the anode accumulated heat capacity becomes smaller, the heat conduction becomes dominant in the cooling, and the X-ray source movement amount gradually becomes smaller. And
Grasping the load input and cooling status on the horizontal axis,
Furthermore, calculate the anode accumulated heat capacity on the vertical axis and grasp it,
By storing these values in the storage device in advance,
The amount of movement of the X-ray source 8 at that time can be immediately read and known according to the heating state of the anode member 3. in this case,
The amount of movement of the X-ray source 8 can be easily and quickly detected without using the X-ray source movement amount detection means having a mechanical structure as shown in FIGS.

FIG. 7 is an enlarged sectional view showing another embodiment of the movement amount canceling means. In this embodiment, the linear actuator 3 is attached to the anode support portion 14 shown in the figure as a movement amount canceling means.
2, an actuator rod 33 and an actuator controller 34 are provided. The linear actuator 32 is composed of a motor unit that supports the actuator rod 33 and linearly expands and contracts in the tube axis direction of the X-ray tube 4. The actuator rod 33 actually expands and contracts a member corresponding to the anode support portion 14, and is provided so as to support the support end plate 16 by connecting the linear actuator 32 and the support end plate 16 at several points. The linear actuator 32 is driven to linearly expand and contract to move the support end plate 16 in the tube axis direction. Further, the actuator controller 34 sends a drive control signal to the linear actuator 32 in order to adjust the expansion and contraction of the actuator rod 33.

With this structure, as in the case of the embodiment shown in FIG. 1, the amount of movement of the X-ray source 8 due to the thermal expansion of the anode member 3 is detected, and the actuator is moved by the length corresponding to this amount of movement. An actuator controller 34 generates a control signal for extending the rod 33, and the linear actuator 32 is driven in response to this control signal, whereby the actuator rod 33 is moved from the cathode member 2 in the tube axis direction of the X-ray tube 4. Stretches away. At this time, the anode target 10 can be moved in the direction opposite to the moving direction of the X-ray source 8 via the support end plate 16 and the fixing screw 17 shown in FIG. The amount of movement can be offset to maintain the position of the operating X-ray source at a constant position.

FIG. 8 is an enlarged sectional view showing a third embodiment of the movement amount canceling means. This embodiment is similar to the embodiment of FIG. 1 except that the structures of the thermal expansion support 29 and the heater wire 28 are changed. In FIG. 8, the anode support 1
4 includes a thermal expansion support 29A and a heater 28A, which is similar to the case of FIG. 1, but the thermal expansion support 29A is cylindrical and made of epoxy resin, and the inner circumference of the heater 28A is It is different in that the heater 28A is a sheet-shaped heater and is wound around the outer circumference of the thermal expansion support 29A. As a material for the thermal expansion support 29A, an epoxy resin having a linear expansion coefficient of about 6 × 10 ⁻⁵ or more and good electric insulation is suitable, but the material is not limited to this and an electric insulation equivalent to this is used. Any material can be used as long as it has heat resistance, heat resistance, oil resistance and a large linear expansion coefficient.

A sheet-shaped heater is suitable as the heater 28A, but a heater wire is wound (or directly) around the entire outer circumference of the thermal expansion support 29A through a heat resistant insulator. Is also good. As a result, the entire thermal expansion support 29A can be heated uniformly. Also, since the sheet-shaped heater is used in the insulating oil 5, oil resistance is required.

In FIG. 8, an elastic body 35 is arranged between the thermal expansion support 29A and the heater 28. This elastic body 35 is wrapped around the sheet-shaped heater 28,
It is arranged in the inner and outer layers of 8A. This elastic body 35 improves the thermal expansion response when the thermal expansion support 29A is directly heated by the heater 28A, but the thermal expansion support 29A is improved.
May cause defects in the member due to local thermal deformation, etc., and serves to buffer this.
As the material of the elastic body 35, a material having heat resistance, oil resistance and an appropriate elongation, such as silicone rubber or fluorine rubber, is preferable, and a sheet-like material is used.

The thermal expansion support 29A, the heater 28A, and the elastic body 35 are provided on the outer circumference of the thermal expansion support 29A.
5, the heater 28A, and the elastic body 35 are arranged in this order and adhered and fixed by an adhesive. In some cases, even if the outermost elastic body 35 is deleted, it is functionally acceptable.

The heater controller 30 is connected to the heater 28A and controls the current flowing through the heater 28A. A temperature sensor 31 is attached to the outer peripheral surface of the thermal expansion support 29A to measure the temperature.

The operation as the movement amount canceling means in this embodiment is the same as that of the embodiment of FIG. 1, and is as described in FIG. Further, similar to the embodiment of FIG. 1, the temperature sensor 31 and the X
It is also possible to include a calculation processing unit for the movement amount of the radiation source in the heater controller 30. Further, in the structure shown in FIG. 8, the arrangement of the thermal expansion support 29A and the heater 28A is not limited to this, and the heater 28A can be replaced by the thermal expansion support 29A.
It may be arranged on the inner circumference of.

The X-ray source movement amount detecting means is not limited to the structure shown in FIG. 2 and FIG. 3, and any means can be used as long as it can detect the movement amount of the X-ray source 8 due to thermal expansion of the anode member 3. It may have any configuration. Further, the movement amount canceling means is not limited to the one shown in FIGS. 1, 7 and 8.
Any structure may be used as long as it expands and contracts in the direction opposite to the moving direction of the X-ray source 8 due to thermal expansion of the anode member 3 and its expansion and contraction can be controlled. Further, although the rotary anode type X-ray tube device is shown in FIGS. 1, 7, and 8, the present invention is not limited to this, and is similarly applicable to a fixed anode type X-ray tube device.

[0043]

Since the present invention is constructed as described above,
The X-ray source movement amount detecting means detects the movement amount of the X-ray source due to the thermal expansion of the anode member caused by the high voltage application between the cathode member and the anode member of the X-ray tube, and the X-ray source movement amount detecting means detects the movement amount of the X-ray source. The movement amount offsetting means provided expands and contracts in a direction opposite to the moving direction of the X-ray source due to thermal expansion of the anode member, and controls the expansion and contraction in accordance with the detected moving amount to move the X-ray source. The amount can be offset. This allows
The position of the X-ray source in the operating X-ray tube can be maintained at a fixed position. Therefore, the image quality of the X-ray image collected by the X-rays emitted by the X-ray tube device can be improved without changing the dose distribution of the X-ray irradiation on the subject.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a main part of an X-ray source movement amount compensation mechanism of an X-ray tube device according to the present invention.

FIG. 2 is a front explanatory view showing a configuration example of X-ray source movement amount detection means in an X-ray CT apparatus.

FIG. 3 is an explanatory side view showing a configuration example of X-ray source movement amount detection means.

FIG. 4 is a flow chart for explaining an operation of canceling the movement of the X-ray source of the anode member by the X-ray source movement detecting means and the movement amount canceling means.

FIG. 5 is a graph showing the relationship between the temperature of the anode support and the elongation of the anode support at that temperature.

FIG. 6 is a graph for explaining another example of the method of knowing the movement amount of the X-ray source.

FIG. 7 is an enlarged cross-sectional view showing another embodiment of the movement amount canceling means.

FIG. 8 is an enlarged cross-sectional view showing a third embodiment of the movement amount canceling means.

FIG. 9 is a cross-sectional view showing an overall configuration of an X-ray tube device according to the present invention and a conventional example.

[Explanation of symbols]

 1 Enclosure 2 Cathode member 3 Anode member 4 X-ray tube 5 Insulating oil 6 Insulating container 6 Thermoelectron 8 X-ray source 9 X-ray 14 Anode support 18 Cathode support 21 X-ray tube device 22 Subject 23 X-ray detection Device 24 Slit 25 X-ray transmission limiting member 26 X-ray source movement detector 28 Heater wire 28A Heater 29, 29A Thermal expansion support 30 Heater controller 31, 31A Temperature sensor 32 Linear actuator 33 Actuator rod 34 Actuator controller 35 Elastic body .

Claims (8)

[Claims] 1. An X-ray tube in which a cathode member and an anode member are arranged inside an envelope so as to face each other, and the inside of the envelope is vacuum-tightly sealed to enclose the cathode member and the anode member. A tube container accommodating insulating oil for cooling the X-ray tube and performing high-voltage insulation around the X-ray tube and enclosing the entire X-ray tube, and an end portion of an anode member of the X-ray tube. Having a positive electrode supporting portion fixed to the inner wall of the tube container, applying a high voltage between the negative electrode member and the positive electrode member of the X-ray tube, and generating heat from the negative electrode member. In an X-ray tube device that emits X-rays from an X-ray source of the anode member when electrons collide with the anode member, an anode member generated by high voltage application between the cathode member and the anode member of the X-ray tube. Corresponding to the amount of movement of the X-ray source due to thermal expansion, it expands and contracts in the direction opposite to the moving direction of the X-ray source, and its extension The X-ray source moving amount canceling means capable of controlling the amount, X-rays source moving amount compensating mechanism of the X-ray tube apparatus characterized by comprising the anode support portion for supporting the anode member. 2. An X-ray source movement amount compensating mechanism for an X-ray tube device according to claim 1, wherein the X-ray source movement amount canceling means has one end connected to an anode support for fixing and supporting the anode member. , The other end is fixed to the inner wall of the tube container, a cylindrical thermal expansion support, a heater attached to the thermal expansion support to heat the thermal expansion support, and the thermal expansion support of the thermal expansion support. A heater controller for detecting the temperature and controlling the heating of the thermal expansion support by the heater so that the expansion of the thermal expansion support can offset the amount of movement of the X-ray source. An X-ray source movement amount compensating mechanism for an X-ray tube device. 3. The X-ray source movement compensating mechanism for an X-ray tube device according to claim 2, wherein the heater controller includes a temperature sensor section for detecting the temperature of the thermal expansion support, and the X-ray. A calculation processing unit that determines the temperature at which the thermal expansion support should rise or fall based on the amount of movement of the source, and a heating current is passed through the heater to increase the temperature of the thermal expansion support, An X-ray source movement compensating mechanism for an X-ray tube device, comprising: a heater current control unit for controlling to stop the heating current of the heater when the temperature of the expansion support is lowered. . 4. An X-ray source movement amount compensating mechanism for an X-ray tube device according to claim 2 or 3, wherein said X-ray source movement amount offsetting means is elastic between said thermal expansion support and said heater. An X-ray source movement amount compensating mechanism for an X-ray tube device, characterized in that a body layer is inserted. 5. An X-ray source movement amount compensating mechanism for an X-ray tube device according to any one of claims 2 to 4, wherein the heater is a sheet-shaped heater. X-ray source movement compensation mechanism. 6. An X-ray source movement amount compensating mechanism for an X-ray tube device according to any one of claims 1 to 5, wherein the X-ray source movement detects an X-ray source movement amount due to thermal expansion of an anode member of the X-ray tube. An X-ray source movement amount compensating mechanism for an X-ray tube device, comprising an amount detecting means. 7. An X-ray source movement amount compensating mechanism for an X-ray tube device according to claim 6, wherein said X-ray source movement amount detecting means has an object table interposed between said X-ray tube device and said X-ray tube movement device. An X-ray detecting member having a slit narrower than the width of the X-ray source is provided in a part of the X-ray detectors facing each other, and an X-ray detecting a change in dose distribution of X-rays incident through the slit. X provided with a source movement amount detector
X-ray source movement amount compensation mechanism of the X-ray tube device. 8. An X-ray source movement amount compensating mechanism for an X-ray tube device according to any one of claims 1 to 5, wherein the movement amount of the X-ray source due to thermal expansion of an anode member of the X-ray tube is determined by the anode of the X-ray tube. An X-ray source movement amount compensation mechanism for an X-ray tube device, which is calculated based on an accumulated heat amount.