JP2001093698A - X-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray tube device capable of miniaturizing or eliminating a blower for cooling. SOLUTION: A pocket 15 for a heat-reserving material is attached on the outer surface of an X-ray tube casing 9, including an X-ray tube 1, an anode support 12, a cathode support 13, insulating oil 7, etc., inside, and a heat reserving material 14 is stored therein. A material with large latent heat of fusion, such as a calcium chloride hydrate, is used as the heat reserving material 14. The heat reserving material 14 is previously frozen in a freezer 16 before taking radiographic photograph. Then the frozen heat reserving material is stored in the pocket 15, and the X-ray tube device is cooled to utilize the latent heat when the heat reserving material 14 is fused. After taking the radiographic photograph, the heat-reserving material 14 is taken out of the pocket 15, frozen in the freezer 16, and recycled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for cooling an X-ray tube apparatus, and more particularly to an improvement in means for cooling insulating oil in an X-ray tube apparatus.

[0002]

2. Description of the Related Art An X-ray tube apparatus is used by being incorporated in a medical X-ray diagnostic apparatus or the like. In the case of examination of digestive organs and the like, an X-ray tube apparatus including a rotating anode X-ray tube as shown in FIG. 2 is generally used. FIG. 2 schematically shows a configuration example of a conventional X-ray tube device. In FIG. 2, an X-ray tube apparatus includes a rotating anode X-ray tube (hereinafter, also referred to as X-ray tube) 1, an X-ray tube container (hereinafter, referred to as tube container) 9 containing the same, and a tube container 9 filled therein. Support that insulates and supports the insulating oil 7 and the anode side of the rotating anode X-ray tube 1 in a tube container 9
12, a cathode support 13 for insulatingly supporting the cathode side of the rotating anode X-ray tube 1 on the inner wall of the tube container 9, and a rotating anode 3 of the rotating anode X-ray tube 1.
And the anode 3 of the rotating anode X-ray tube 1
And a cable receptacle (not shown) for introducing a high voltage applied to the cathode 2.

The rotating anode X-ray tube 1 is composed of a cathode 2 and a rotating anode 3 which are arranged to face each other, and an envelope 6 which supports the electrodes 2 and 3 and hermetically seals them in a vacuum. On the cathode 2, a focusing electrode 11 in which a filament for emitting thermoelectrons is mounted in a focusing groove is disposed at an eccentric position. Rotating anode 3
Is the target plate 4 arranged opposite to the focusing electrode 11.
And a rotating unit 5 that rotatably supports the target plate 4.

When the rotating anode X-ray tube 1 is operated, a high voltage of 40 to 150 kV is applied between the cathode 2 and the rotating anode 3, and a filament heating voltage is applied to the cathode 2 filament. The electrons are emitted and accelerated toward the target plate 4. This flow of thermoelectrons (electron beam)
Are focused by the focusing groove of the focusing electrode 11 to form a focal point (X-ray source) on the target plate 4.

[0005] Most of the input applied to the rotating anode X-ray tube 1 is converted into X-rays and heat at and near the focal point of the target plate 4. X-rays generated at the focal point
The X-ray is taken out of the tube container 9 through an X-ray emission window 10 attached to the X-ray, and is effectively used for X-ray diagnosis and the like.
Since the conversion efficiency of the X-ray tube input to X-ray is less than 1%, most of the X-ray tube input is converted to heat.

The heat generated at the focal point of the target plate 4 and in the vicinity thereof is dissipated by heat radiation from the surface of the target plate 4 and heat conduction through the rotating anode 3. Most of the heat is dissipated by the heat radiation from the target plate 4, and these heats are transferred to the envelope 6, and then the insulating oil 7 surrounding the envelope 6
Heat is transferred by convection.

[0007] In order to rotate the rotating anode 3 of the rotating anode X-ray tube 1, a stator 8 is arranged on the outer periphery of the rotating anode 3. Immediately before the application of a high voltage load to the rotating anode X-ray tube 1, an AC voltage of about 100 to 500 V is applied to the stator 8, and the rotating anode 3 rotates at a maximum rotational speed of 2,700 to 10,000 rpm. At this time, heat is generated in the stator 8 due to copper loss and iron loss, and this heat is also transferred to the insulating oil 7 by convection.

The heat is dissipated using the insulating oil 7 as a heat medium. When the blower 27 is attached to the outside of the tube container 9 and cooled by forced convection as shown in FIG.
The heat accumulated in the insulating oil 7 inside is transferred to the tube container 9 by convection, and is radiated from the outer surface of the tube container 9 to the outside air. In this case, air is blown to the outer surface of the tube container 9 by the blower 27 disposed outside the tube container 9, and forced convection of the air occurs, thereby increasing the cooling effect of the X-ray tube device.

If the X-ray tube 1 is used frequently in a short time,
The amount of heat generated in the X-ray tube device exceeds the amount of heat released to the outside of the X-ray tube device, heat is accumulated in the X-ray tube device, and the insulating oil 7
Temperature rises. The temperature of the insulating oil 7 is limited by the physical properties of the X-ray tube 1, the anode support 12, the cathode support 13, the stator 8, and the like, or the physical properties of the insulating oil 7 itself, especially the dielectric strength, and is generally 70 to 90. C is the upper limit.

When the temperature of the insulating oil 7 reaches the upper limit temperature, the temperature is detected by a temperature detecting mechanism attached to the X-ray tube device, a detection signal is sent to the X-ray device side, and the use of the X-ray tube device is continued. That is, application of a high voltage load to the X-ray tube device is prohibited. In order to avoid such use prohibition of the X-ray tube device, measures are being taken to increase the cooling capacity of the X-ray tube device by increasing the size of the blower 27 or attaching a heat exchanger.

[0011]

As described above, in order to use the X-ray tube apparatus frequently, it is necessary to increase the size of a blower for cooling the X-ray tube apparatus. As a result, the size of the entire X-ray tube apparatus also increases. further,
The noise of the whole X-ray tube device also increases. For this reason, an object of the present invention is to provide an X-ray tube device which can reduce the size of a blower for cooling or omit the blower by improving the cooling means.

[0012]

To achieve the above object, an X-ray tube apparatus according to the present invention comprises an X-ray tube, a container for accommodating the X-ray tube (hereinafter referred to as a tube container), and an X-ray tube. A support member for insulatingly supporting the tube on the inner wall of the tube container, a high voltage introducing means for applying a high voltage to the X-ray tube, and insulating and cooling the X-ray tube filled in the tube container In an X-ray tube device including insulating oil, a heat storage material made of a substance having a large latent heat of fusion is cooled to a state of operation of the heat storage material by cooling means provided outside the X-ray tube device, and the outer surface of the tube container is cooled. To cool the insulating oil in the tube container (claim 1).

In this configuration, since the heat storage material made of a substance having a large latent heat of fusion is attached to the outer surface of the tube container in a state solidified by cooling means such as a refrigerator, the heat storage material has a large heat absorbing ability, and The insulating oil can be cooled via the container. In addition, since the cooling of the insulating oil is performed by the heat storage material, the conventionally used blower becomes unnecessary, or even if it is used, a small capacity can be used. Therefore, the X-ray tube device as a whole is small and compact. And the noise of the X-ray tube device can be reduced.

In the X-ray tube apparatus according to the present invention, a heat storage material container capable of storing the heat storage material is attached to the outer surface of the tube container, and the heat storage material is stored in the heat storage material container. . In this configuration, before the input load is applied to the X-ray tube (during standby), the heat storage material is cooled using the cooling means, and the X-ray tube is cooled.
When the X-ray tube device is used, the solidified heat storage material is stored in the heat storage material container to cool the X-ray tube device. Thus, since the heat storage material is detachable, the heat storage material can be reused.

Further, in the X-ray tube apparatus according to the present invention, the heat storage material is made of a substance having a large latent heat of fusion, such as calcium chloride hydrate, which melts at a temperature lower than the maximum insulating oil temperature when the X-ray tube apparatus is used. . In this configuration, since the heat storage material is melted at a temperature lower than the maximum insulating oil temperature when the X-ray tube device is used, the large latent heat of fusion of the heat storage material can be effectively used, and a large cooling capacity can be exhibited. .

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows the configuration of a first embodiment of the X-ray tube apparatus according to the present invention. FIG. 1 shows a structure of an X-ray tube device in which a heat storage material, which is a main part of the present invention, is mounted on the outer surface of a tube container. In FIG. 1, the X-ray tube 1 is supported on the inner wall of a tube container 9 by a cathode support 13 on the cathode side and by an anode support 12 on the anode side. The X-ray tube 1 comprises a cathode 2 for emitting an electron beam, a target plate 4 for emitting X-rays upon collision of the electron beam, a rotating anode 3 comprising a rotating part 5 for rotatably supporting the same, and a cathode 2. And the rotating anode 3 are insulated and supported at opposite positions and sealed in a vacuum-tight manner.
6 is provided.

An insulating oil 7 is filled in a tube container 9 and an X-ray tube
1 is responsible for the role of insulation and cooling. Rotating part of X-ray tube 1
A stator 8 is arranged around 5, and a motor is configured by a combination of the rotor and the stator 8 included in the rotating unit 5,
This rotating part 5 is rotated at high speed. Along with the rotation of the rotating unit 5, the target plate 4 rotates. At the center of the tube container 9, near the target plate 4 of the X-ray tube 1,
X-ray emission window 10 for taking out the X-rays generated in 4 to the outside
Is attached. A cable receptacle (not shown) for introducing a high voltage applied to the anode 3 and the cathode 2 of the X-ray tube 1 is attached to the anode side and the cathode side in the tube container 9.

In the thus constructed X-ray tube apparatus, when a high voltage is applied between the cathode 2 of the X-ray tube 1 and the rotating anode 3, the electron beam emitted from the cathode 2 collides with the target plate 4. Then, while radiating X-rays, most of the energy of the electron beam is converted into heat and heats the target plate 4. X-rays emitted from the focal point of the target plate 4 are taken out of the X-ray emission window 10 and used for X-ray diagnosis or the like. On the other hand, the heat generated in the target plate 4 is transmitted through the envelope 6 or
The heat is radiated to the insulating oil 7, the temperature of the insulating oil 7 rises, and the heat is stored in the insulating oil 7.

The insulating oil 7 includes, in addition to the heat generated in the target plate 4, a stator for rotating the rotating part 5 of the rotating anode 3.
The heat generated at 8 and the heat from the filament of the cathode 2 are radiated. The heat stored in the insulating oil 7 is transferred to the tube container 9 by convection.
The heat is transferred to the inner wall of the tube case 9, heat is conducted inside the tube case 9, and is radiated from the outer surface of the tube case 9 into the air by natural convection or forced convection.

In the present embodiment, in order to cool the heat accumulated in the insulating oil 7, a method is employed in which the outer surface of the tube container 9 is directly cooled by heat conduction, not by convection.
That is, the heat storage material 14 described below is attached to the outer surface of the tube container 9.
To absorb the heat of the insulating oil 7 in the tube container 9.

In FIG. 1, two heat storage material pockets 15 are provided on the outer peripheral surfaces of the tube container 9 on the cathode side and the anode side, and two heat storage materials 14 are mounted in the heat storage material pockets 15. Have been. The heat storage material 14 is made of a substance that melts at room temperature or slightly below room temperature, for example, several degrees higher than the room temperature of the inspection room in which the X-ray tube device is used, and has a high latent heat of fusion. In the present embodiment, the heat storage material 14 is cooled in a freezer or a refrigerator separately prepared and solidified and mounted in the heat storage material pocket 15 for use. The details of the heat storage material 14 will be described later.

In this embodiment, the heat storage material 14 is filled in a container made of a metal having good heat conductivity and solidified. The metal container is provided with a handle or the like so as to be easily carried when the heat storage material 14 is replaced. When the metal container is housed in the heat storage material pocket 15, one surface comes into contact with the outer surface of the tube container 9, so that only one of the surfaces has improved thermal conductivity. You may.

In the example of FIG. 1, two heat storage materials 14 are mounted. However, the number of heat storage materials 14 may be one or three or more, and a cooling effect corresponding to the number of heat storage materials 14 mounted can be obtained. When only one is mounted, the cooling effect is greater when the insulating oil 7 is mounted on the anode side where the temperature is high.

With respect to the heat storage material 14, the freezer 16
In this state, it is cooled and solidified to maintain a high latent heat of fusion (hereinafter, this state is referred to as having a cooling capacity). Heat storage material 14 having such a cooling capacity
Is attached to the heat storage material pocket 15 installed on the surface of the tube container 9 immediately before the start of use of the X-ray tube device, and the X-ray tube device is cooled. At the end of use of the X-ray tube apparatus and at the time of suspension of use, the heat storage material 14 is removed from the heat storage material pocket 15, and is cooled and solidified in a freezer 16 or the like, and the cooling capacity of the heat storage material 14 is restored to be used again. In the present embodiment, in order to cool and solidify the heat storage material 14, a separately prepared freezer 16 is used.However, the cooling means of the coolant 14 is not limited thereto.
A refrigerator or the like may be used.

In the method of cooling the surface of the tube container 9 with the coolant 14 as in the present embodiment, the X-ray tube device is cooled by natural convection of the insulating oil 7 filled in the tube container 9. Therefore, in this cooling method, for example, when the melting point of the heat storage material 14 is 25 ° C., if the amount of heat generated by the X-ray tube 1 is about 150 W, it can be sufficiently cooled.

Various substances can be considered as the substance constituting the heat storage material 14 used in the present invention. A substance suitable for the heat storage material 14 has a high latent heat of fusion and a melting point lower than the maximum insulating oil temperature when the X-ray tube device is used. A typical example of such a substance is calcium chloride hydrate (melting point: 28 ° C., latent heat of fusion: 200.6 kJ / kg). In addition, ethylene glycol or the like is used.

The freezer 16 for cooling and solidifying the heat storage material 14 needs a capacity for storing the heat storage material 14 used for cooling the X-ray tube device. As for the number of heat storage materials 14, it is preferable to prepare twice the number used for cooling the X-ray tube device. By doing so, when the X-ray tube device is cooled by, for example, two heat storage materials 14, the other two heat storage materials 14 can be frozen and solidified in the freezer 16 during the cooling, so that the X-ray tube device is almost continuously cooled. Thus, the X-ray tube device can be cooled by the two heat storage materials 14.

In the present embodiment, the X-ray tube device can be cooled by attaching a heat storage material pocket 15 in which the heat storage material 14 is mounted on the outer peripheral surface of the tube container 9, so that the forced convection by the conventional blower can be performed. There is no need to attach a large blower to the X-ray tube device as in the case of cooling.
Even if a blower is attached, the cooling by the heat storage material 14 is supplemented, so that a small blower is sufficient. As a result, the cooling capacity of the entire X-ray tube device is improved, and a small and compact device with low noise can be obtained.

[0029]

According to the conventional cooling method using a blower or the like of the X-ray tube device, the cooling capacity is reduced due to an increase in the outside air temperature on the outer periphery of the X-ray tube device. , A substantially constant cooling capacity can be ensured irrespective of a change in the outside air temperature, noise can be reduced, and a compact device can be obtained.

[Brief description of the drawings]

FIG. 1 is a view schematically showing the configuration of a first embodiment of an X-ray tube apparatus according to the present invention.

FIG. 2 is a view schematically showing a configuration example of a conventional X-ray tube device.

[Explanation of symbols]

 1 ... rotating anode X-ray tube (X-ray tube) 2 ... cathode 3 ... rotating anode 4 ... target plate 5 ... rotating part 6 ... envelope 7 ... insulating oil 8 ... stator 9 ... X-ray tube container (tube container) 10 ... X-ray emission window 11 ... focusing electrode 12 ... anode support 13 ... cathode support 14 ... heat storage material 15 ... pocket for heat storage material 16 ... freezer

Claims (1)

[Claims] 1. An X-ray tube, an X-ray tube container (hereinafter abbreviated as a tube container) for accommodating the X-ray tube, and a support member for insulatingly supporting the X-ray tube on an inner wall of the tube container. In an X-ray tube apparatus comprising: a high-voltage introducing means for applying a high voltage to the X-ray tube; and an insulating oil filled in the tube container to insulate and cool the X-ray tube. Cooling a heat storage material made of a large substance to an operation state of the heat storage material by cooling means provided outside the X-ray tube device, attaching the heat storage material to an outer surface of the tube container, and cooling insulating oil in the tube container. Characteristic X-ray tube device.