JP4231648B2 - X-ray high voltage apparatus and X-ray diagnostic imaging apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray high-voltage apparatus that generates a high voltage for emitting X-rays from an X-ray tube and an X-ray diagnostic imaging apparatus using the same, and in particular, a large X-ray dose from an X-ray tube at a high load factor. The present invention relates to an X-ray high voltage apparatus capable of supplying electric power for radiation to the X-ray tube, and an X-ray diagnostic imaging apparatus capable of performing high-functionality, high image quality, and high throughput imaging using the X-ray high voltage apparatus.
[0002]
[Prior art]
An X-ray imaging apparatus and an X-ray computed tomography apparatus (hereinafter referred to as “X-ray imaging apparatus”) that apply a DC high voltage from an X-ray high-voltage apparatus to an X-ray tube and irradiate the subject with X-rays emitted from the X-ray tube. X-ray CT diagnostic apparatuses) are widely used in the field of medical image diagnostic apparatuses. In recent years, these X-ray diagnostic imaging apparatuses are required to have a so-called high load factor X-ray generator that outputs a large amount of X-rays over a long period of time in order to cope with a new imaging method. In particular, in the X-ray CT apparatus, features such as “a wide range of scanning is possible in a short time”, “continuous data can be obtained in the body axis direction, thereby enabling generation of a three-dimensional image”, etc. Rotational CT called helical scan or spiral scan is popular.
[0003]
In this spiral CT, the X-ray tube and the X-ray detector are continuously rotated, and at the same time, the bed on which the subject is placed is continuously moved in the body axis direction of the subject, so that the X-ray tube and the X-ray The detector is rotated relative to the subject. In this way, during the spiral scan imaging, the imaging position is also changed in parallel with the continuous rotation scan, so that the overall imaging time is shortened. Further, since continuous scanning is also performed in the body axis direction during photographing, three-dimensional data is collected.
[0004]
In this case, in order to realize the rotation scan, it is necessary to continuously rotate the scanner rotating plate supporting the X-ray tube and the X-ray detector. For that purpose, the X-ray tube mounted on the scanner rotating plate is continuously connected. Thus, a means for supplying power is required. As this means, a power transmission mechanism composed of a slip ring and a brush is used, and at least an X-ray tube and a high voltage (hereinafter referred to as a tube voltage) are applied to the X-ray tube on the scanner turntable. A high-voltage generator for applying is mounted, and electric power for generating required X-rays from the X-ray tube is supplied to the high-voltage generator via the power transmission mechanism.
[0005]
Thus, since the high voltage generator is mounted on the scanner turntable and rotated at a high speed, it is desirable that the weight be as light as possible. For this reason, an inverter type X-ray high voltage apparatus that can reduce the size and weight of the high voltage transformer of the high voltage generator and reduce the pulsation of the tube voltage is used for the X-ray high voltage apparatus.
[0006]
This inverter type X-ray high voltage device converts a commercial AC power source into a DC voltage with a converter, converts this DC voltage into an AC voltage with a frequency higher than the commercial power source frequency with an inverter, Is boosted by a high voltage transformer, the boosted AC high voltage is rectified to a DC high voltage by a high voltage rectifier, and the DC high voltage is applied to an X-ray tube to generate X-rays. ing. In order to reduce the size of the high voltage transformer and reduce the pulsation of the tube voltage waveform, the inverter operating frequency is increased to 20 kHz or higher.
[0007]
[Problems to be solved by the invention]
In this case, rotational CT has a long imaging time due to continuous scanning, and in recent years, there is no motion artifact and the heart can be diagnosed. There is a demand for one scan time of 0.5 seconds or less.
[0008]
Therefore, in order for one scan time to correspond to 0.5 seconds, the scanner turntable has to be rotated once in 0.5 seconds, so the unit is inversely proportional to the scanner rotation time compared to the conventional low-speed device. The X-ray dose per hour must be increased.
[0009]
That is, in order to obtain a good tomographic image with less granular noise, a large amount of current flowing between the anode and cathode of the X-ray tube (hereinafter referred to as tube current) is caused to flow in inverse proportion to the scanner rotation speed, and a sufficient X-ray dose is obtained. To generate X-rays to the subject, and the tube current becomes larger than that of the conventional one. For this reason, an X-ray tube with a large allowable load is required due to an increase in tube current due to an increase in scanning time and an increase in imaging time due to a spiral scan, and an X-ray for supplying power to the X-ray tube is required. High output power devices have also become necessary. Specifically, an X-ray generator that can output 60 kW or more continuously for 1 minute or more is required. That is, an X-ray tube having a large X-ray dose and a high load factor and an X-ray high voltage apparatus having a large output and a high load factor are required. In particular, in an X-ray high-voltage device, there is a limit to simply increasing the output of each part constituting the X-ray high-voltage device using conventional techniques, and cooling is also required. Among them, a high voltage transformer that boosts the output voltage of the inverter and a high voltage rectifier that rectifies the output voltage of the high voltage transformer to a DC high voltage include a smoothing capacitor that smoothes the output voltage of the high voltage rectifier, and X Since it is only immersed in insulating oil in a container (hereinafter referred to as a high voltage tank) together with a heating transformer for heating the filament that is the cathode of the ray tube, the temperature of the insulating oil increases. There is a concern that the insulation withstand voltage will be reduced and the electrical components housed in the high voltage tank will fail. Hereinafter, this problem will be described in detail.
[0010]
The main losses occurring in the high-voltage tank in which the high-voltage transformer, high-voltage rectifier, and the like are housed are listed as follows in order of magnitude.
(1) Copper loss that occurs in the primary and secondary windings of the high-voltage transformer
(2) Iron loss that occurs in the magnetic core of the high-voltage transformer
(3) Conduction loss and switching loss in high voltage rectifier
(4) Loss caused by heating transformer
(5) Loss caused by wiring and smoothing capacitor High voltage transformers cause the largest loss of several kilowatts in a short time due to the causes of (1) and (2) above. However, its constituent materials are iron-based magnetic cores, conductors, insulators, etc. Even if the surrounding insulating oil temperature rises to 100 ° C., no seizure or defective breakdown voltage occurs. The same applies to the heating transformer.
[0011]
Further, the smoothing capacitor itself has a small loss, and there is no fear of breakage or shortening of the life if the ambient insulating oil temperature is about 85 ° C., for example.
[0012]
However, the high voltage rectifier is configured by connecting a number of semiconductor elements, here, diodes in series, and conduction loss occurs due to the product of the current flowing through the diode and the voltage drop in the forward direction of the diode at this time. In addition, the high-frequency AC power supplied from the high-voltage transformer causes a switching loss in the diode of the high-voltage rectifier, and the loss of both causes the junction temperature of the diode to be, for example, 50 ° C. from the surrounding insulating oil temperature. It rises by about ℃. The allowable junction temperature of high-voltage diodes capable of high-frequency operation is up to about 130 ° C, so the insulating oil temperature around the high-voltage rectifier must be 130 ° C-50 ° C = 80 ° C or less. If the voltage exceeds the range, there is a concern that the leakage current of the diode inside the high-voltage rectifier increases, and that it is damaged due to thermal runaway.
[0013]
As described above, as the X-ray CT apparatus is used at a higher X-ray dose and higher load factor than before, the possibility of such a problem increases, and the insulating oil temperature around the high-voltage transformer is increased. It may happen that the temperature exceeds 100 ° C., and there is a concern that this high-temperature insulating oil flows into the vicinity of the adjacent high-voltage rectifier and the high-voltage rectifier is damaged.
[0014]
Accordingly, an object of the present invention is to reduce the temperature in the high-voltage tank that houses the components of the high-voltage generator to an allowable temperature or less, and to generate electric power for radiating a large X-ray dose from the X-ray tube at a high load factor. An object of the present invention is to provide an X-ray high voltage apparatus that can be supplied to an X-ray tube and an X-ray diagnostic imaging apparatus that can perform high function, high image quality, and high throughput imaging using the X-ray high voltage apparatus.
[0015]
[Means for Solving the Problems]
The above object is achieved by the following means.
(1) AC power source, a transformer connected to the AC power source and boosting the voltage, a rectifier connected to the transformer and rectifying the boosted AC voltage, and an output voltage of the rectifier supplied to the X-ray tube An X-ray high-voltage device that includes a container (high-voltage tank) that houses at least the transformer and the rectifier, a refrigerant filled in the container, a heat-dissipating cooling device that radiates and cools the refrigerant, A pipe connecting between the container and the heat-dissipating cooling device, a pump for transporting a refrigerant through the pipe to the container and the heat-dissipating cooling device, a first duct built in the transformer and including the transformer , a built-in rectifier and a second duct which is built in the container, as the refrigerant in the first duct is guided to the radiator cooling device, wherein the first duct is connected to the pipe, the the radiator cooling refrigerant in the second duct As derived from the device, in the second X-ray high voltage unit duct is connected to the pipe, the refrigerant in the container is sucked into the first duct, the refrigerant in the second duct The X-ray high-voltage apparatus , wherein the container, the first duct, and the second duct are connected so as to diffuse into the container .
(2), characterized in that shoot by irradiating the X-rays emitted from the X-ray tube output DC high voltage of the X-ray high voltage device is applied to the X-ray tube of (1) to the subject X-ray image diagnostic apparatus.
[0016]
As described above, since the insulating oil in the high voltage tank that houses the components of the high voltage generator of the X-ray high voltage device is cooled by the radiator, the high voltage rectifier and the high voltage in the high voltage tank are The electric power for radiating a large X-ray dose from the X-ray tube at a high load factor can be supplied to the X-ray tube by setting the transformer or the like below the allowable temperature. In particular, for high voltage transformers that have a large loss and the temperature of the surrounding insulating oil is likely to rise, if the insulating oil cooled by a radiator is configured to restrict the flow line of the insulating oil by a duct, the insulating oil The flow rate becomes faster and the heat transfer efficiency from the high voltage transformer to the insulating oil is improved.
[0017]
In addition, the structure in which the insulating oil heated around the high-voltage transformer is directly guided to the radiator via a pump by a duct, so that the high-temperature insulating oil causes thermal damage to other parts of the high-voltage tank. In addition, since the temperature of the insulating oil flowing into the radiator rises, the heat dissipation efficiency by the radiator is dramatically improved, and the temperature of the insulating oil inside the high voltage tank can be further lowered. By using an X-ray high-voltage apparatus equipped with such a high-cooling structure high-voltage generator for an X-ray diagnostic imaging apparatus, it is possible to perform imaging with high functionality, high image quality, and high throughput, This is particularly effective for an X-ray CT apparatus that requires long-time imaging with a large X-ray dose.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall configuration diagram of an X-ray CT apparatus when the X-ray high voltage apparatus according to the present invention is used in an X-ray CT apparatus.
[0019]
In FIG. 1, 101 is an AC power source, 102a and 102b are connected to the AC power source 101, brushes for transmitting the AC voltage of the AC power source 101 to the rotating portion 108 of the scanner, and 111a and 111b are in contact with the brushes 102a and 102b. While the slip ring rotating with the scanner rotating unit 108, 104 is a converter connected to the slip rings 111a and 111b to convert the alternating voltage into direct current, 103 is a capacitor connected to the converter 104 and smoothes the output voltage of the converter, 105 is an inverter that converts the DC voltage smoothed by the capacitor 103 into a high-frequency AC voltage, 106 is a high-voltage transformer that is connected to the inverter 105 and boosts the high-frequency AC voltage that is the output voltage, and 107 is a high-voltage transformer 106 is a rectifier that converts the boosted AC high voltage to DC, 109 is a smoothing capacitor for smoothing the output voltage of the high voltage rectifier 106, and 110 is a high voltage regulator. Connected to the vessel is an X-ray tube for generating X-rays by the application of the DC high voltage. Reference numeral 205 denotes a heating inverter, and this output AC voltage is connected to the heating transformer 201. Further, the secondary side of the heating transformer is connected to the filament on the cathode side of the X-ray tube 110, and to the X-ray tube 110, Control the flowing tube current.
[0020]
Here, the converter 104, the smoothing capacitor 103, the inverter 105, the high voltage transformer 106, the high voltage rectifier 107 and the smoothing capacitor 109 constitute the X-ray high voltage device 100, and the high voltage transformer 106, the high voltage rectifier 107, The smoothing capacitor 109 and the heating transformer 204 are mounted inside the high voltage tank 204 while being filled with insulating oil (not shown). The insulating oil is sucked up by a pump 207 through a duct, which will be described later, and guided to a radiator 206, where the insulating oil is cooled, and this cooled insulating oil is passed through a duct, which will be described later, in the high-voltage tank 204. It is set as the structure sent out to. X-rays radiated from the X-ray tube 110 pass through the subject 118, are detected by the X-ray detector 116 constituting the X-ray detector 115, and are further amplified by the amplifier 117. 111c is a slip ring mounted on the rotating unit 108 of the scanner, 102c is a brush that transmits an X-ray detection signal output from the amplifier 117 while contacting the slip ring 111c, and 112 is an X-ray detection signal transmitted from the brush. An image processing apparatus 113 that generates a tomogram from the image processing apparatus 113 is an image display apparatus that is connected to the image processing apparatus 112 and displays the generated tomogram. The X-ray generator including the X-ray high voltage device 100 and the X-ray tube 110 and the X-ray detection unit 107 are mounted on a scanner rotation unit 108, and the scanner rotation unit 108 and a subject 109 (not shown) are placed thereon. The X-ray CT apparatus is composed of three units including a bed and a console (not shown) including the image processing device 112 and the image display device 110. FIG. 1 shows an example in which the entire X-ray high-voltage apparatus, the pump 207 and the radiator 206 are mounted on the scanner rotating unit 108. However, the present invention is not limited to this, and the X-ray high-voltage apparatus 100 includes As long as at least the high voltage tank 204 can be mounted, the inverter 105 and the high voltage tank 204 may be mounted. Further, the pump 207 and the radiator 206 may not be mounted on the scanner rotating unit 108 but may be provided outside the scanner rotating unit 108. In this case, a means for sending and feeding the insulating oil in the high voltage tank 204 to the pump 207 and the radiator 206 is necessary, but this means is different from the object of the present invention and is omitted here.
[0021]
FIG. 2 shows a first embodiment of the internal structure of the high-voltage tank 204 which is the main part of the present invention.
[0022]
In FIG. 2, 209 is a terminal for connecting the AC output voltage from the inverter 105 to the high voltage transformer 106 in the high voltage tank 204, 202 and 203 are for supplying a DC high voltage to the X-ray tube 110, respectively. Bushing. The high voltage tank 204 contains a high voltage transformer 106, a high voltage rectifier 107, a smoothing capacitor 109, and a heating transformer 201, and is filled with insulating oil.
[0023]
A duct 208 is built in the high-voltage tank 204 and includes the high-voltage transformer 106 and the high-voltage rectifier 107. The duct 208 is filled with insulating oil in the same manner as the entire high-voltage tank 204. 207 is a pump that is connected to the duct 208 and sucks the refrigerant, that is, the insulating oil, and 206 is a radiator that is connected to the pump 207 and releases the thermal energy of the insulating oil in the duct 208. The insulating oil connected to 208 and cooled by the radiator 206 is sent to the duct 208, and the high-voltage transformer 106 and the high-voltage rectifier 107 are cooled by the cooled insulating oil. By configuring the high-voltage tank 204 as shown in FIG. 2, the insulating oil cooled to near the outside temperature by the radiator 206 is circulated around the high-voltage rectifier 107 through the duct 208, so that the high-voltage rectifier 107 Since the ambient temperature is kept near the outside temperature and the high-temperature insulating oil around the high-voltage transformer does not circulate, it is ensured that the diode junction temperature inside the high-voltage rectifier 107 will rise abnormally and cause damage. Can be prevented.
[0024]
In addition, the high-voltage transformer 106 that has the greatest loss and the temperature of the surrounding insulating oil is likely to rise is restricted by the duct 208 and the flow line of the insulating oil is restricted. The heat transfer efficiency to the oil 205 is improved. Furthermore, the insulating oil heated around the high-voltage transformer is guided to the duct 208 and directly to the radiator 206 via the pump 207, so that the high-temperature insulating oil is supplied to the other of the high-voltage tank 204. In addition to causing no thermal damage to the components, the temperature of the insulating oil flowing into the radiator 206 rises, so that the heat dissipation efficiency by the radiator 206 is dramatically improved. As a result, the temperature of the insulating oil 205 inside the high-voltage tank 204 can be kept low even if the converter 104 and the inverter 105 are increased in current, thereby enabling an X-ray high-voltage device corresponding to a large output and a high load factor. It becomes.
[0025]
FIG. 3 shows a second embodiment of the internal structure of the high voltage tank 204, which is the main part of the present invention.
[0026]
The second embodiment of FIG. 3 is obtained by dividing the duct 208 of the first embodiment shown in FIG. 2 into 208 ′ and 208 ″. In the high voltage tank of FIG. 2, a high voltage that can be cooled by a radiator. The only components in the tank were the high-voltage rectifier 107 and the high-voltage transformer 106. Other than that, there was only natural heat radiation from the outer wall of the high-voltage tank 204.
[0027]
In contrast, in the second embodiment shown in FIG. 3, the insulating oil that has been guided by the duct 208 ″ and cooled the high-voltage rectifier 107 is once diffused into the high-voltage tank 204, and again, the duct 208 ′. After the high voltage transformer 106 is efficiently cooled, it is sucked up by the pump 207, radiated by the radiator 206, cooled, and returned to the duct 208 "again. In this case, heat generated by the smoothing capacitor 109 and the heating transformer 201 is also efficiently dissipated by the radiator 206, and the entire high voltage tank 204 is efficiently cooled. Note that the duct of the high voltage rectifier is not necessarily required if heat generation other than in the high voltage transformer is not a problem.
[0028]
In addition, the embodiment shown in FIG. 2 and FIG. 3 circulates the insulating oil cooled by the radiator to cool the high-voltage rectifier that is weak in temperature first, and finally, is tough in temperature and generates heat. The order in which the large high-voltage transformer is cooled and led to the outside is clarified. For this purpose, the duct is used to form a flow path for insulating oil, which is a refrigerant.
[0029]
Therefore, the present invention does not limit the shape of the duct, and may be any shape as long as the order of the external cooling device, the high voltage rectifier periphery, the high voltage transformer periphery, and the external cooling device can be defined. For the same reason, the order of the radiator and the pump may be either, or a pump may be provided inside the high voltage tank. In the above embodiment, in order to efficiently cool the high voltage rectifier and the high voltage transformer having a large calorific value, the high voltage rectifier and the high voltage transformer are surrounded by a duct. If it is not necessary to specifically cool only the voltage rectifier and the high voltage transformer, and it is sufficient to simply cool the inside of the high voltage tank, the pump 207 is used to supply the insulating oil to the radiator 206 outside the high voltage tank 204. The insulating oil cooled by the radiator 206 may be returned to the high voltage tank 204 again.
[0030]
Further, although a radiator is used as the heat radiating device here, a heat pump type cooler, a heat exchanger using another medium, or a cooler using the Peltier effect may be used in combination.
[0031]
As described above, the inside of the high voltage tank is cooled to constitute an X-ray high voltage apparatus corresponding to a large output and a high load factor, and by applying this X-ray high voltage apparatus to the X-ray CT apparatus, scanning can be performed. It is possible to provide an X-ray CT apparatus that contributes to enhancement of functions such as cardiac imaging by speeding up, improvement of throughput by shortening of imaging time, and improvement of image quality by large X-ray imaging.
[0032]
In the above, the case where the X-ray high voltage apparatus of the present invention is used in an X-ray CT apparatus as an example of application to an X-ray diagnostic imaging apparatus has been described. However, the present invention is not limited to this, and the X-ray CT is not limited thereto. Needless to say, the present invention is effective for use in a circulatory X-ray diagnostic apparatus and other X-ray image diagnostic apparatuses that require a high-output X-ray high-voltage apparatus other than the apparatus.
[0033]
【The invention's effect】
As described above, according to the present invention, since the insulating oil in the high-voltage tank that houses the components of the high-voltage generator is cooled by the radiator, the high-voltage rectifier and the high-voltage transformer in the high-voltage tank, etc. The X-ray high voltage apparatus for supplying the X-ray tube with electric power for radiating a large X-ray dose from the X-ray tube at a high load factor can be provided. In particular, for high voltage transformers that have a large loss and the temperature of the surrounding insulating oil is likely to rise, if the insulating oil cooled by a radiator is configured to restrict the flow line of the insulating oil by a duct, the insulating oil The flow rate becomes faster and the heat transfer efficiency from the high voltage transformer to the insulating oil is improved.
[0034]
In addition, the structure in which the insulating oil heated around the high-voltage transformer is directly guided to the radiator via a pump by a duct, so that the high-temperature insulating oil causes thermal damage to other parts of the high-voltage tank. In addition, since the temperature of the insulating oil flowing into the radiator rises, the heat dissipation efficiency by the radiator is dramatically improved, and the temperature of the insulating oil inside the high voltage tank can be further lowered. By using an X-ray high-voltage apparatus equipped with such a high-cooling structure high-voltage generator for an X-ray diagnostic imaging apparatus, it is possible to perform imaging with high functionality, high image quality, and high throughput, This is particularly effective for an X-ray CT apparatus that requires long-time imaging with a large X-ray dose.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an X-ray CT apparatus when the X-ray high-voltage apparatus according to the present invention is used in an X-ray CT apparatus.
FIG. 2 shows a first embodiment of the internal structure of a high-voltage tank which is a main part of the present invention.
FIG. 3 shows a second embodiment of the internal structure of a high-voltage tank, which is a main part of the present invention.
[Explanation of symbols]
100 ... X-ray high voltage device, 101 ... AC power supply, 111a, 111b, 111c ... slip ring, 102a, 102b, 102c ... brush, 104 ... converter, 105 ... inverter, 106 ... high voltage transformer, 107 ... high voltage rectifier , 108: Rotating part of scanner, 109 ... Smoothing capacitor, 110 ... X-ray tube, 112 ... Image processing device, 113 ... Image display device, 115 ... X-ray detector, 116 ... X-ray detector, 117 ... Amplifier, 118 ... Subject, 201 ... Heating transformer, 204 ... High voltage tank, 207 ... Pump, 206 ... Radiator

Claims (2)

AC power source, a transformer connected to the AC power source and boosting the voltage, a rectifier connected to the transformer and rectifying the boosted AC voltage, and an X-ray supplying the output voltage of the rectifier to the X-ray tube A high-voltage device, a container that houses at least the transformer and the rectifier, a refrigerant filled in the container, a heat-dissipation cooling device that radiates and cools the refrigerant, and a space between the container and the heat-dissipation cooling device. a connecting pipe, built a pump for conveying the refrigerant to the container and the heat radiation cooling device through the pipe, a first duct being built into the container incorporates the transformer, the vessel incorporates the rectifier a second duct which is, as the refrigerant in the first duct is guided to the radiator cooling device, wherein the first duct is connected to the pipe, the refrigerant in the second duct Guided from the heat dissipation cooling device To so that, in the X-ray high voltage apparatus in which the second duct is connected to the pipe,
The container, the first duct, and the second duct are connected so that the refrigerant in the container is sucked into the first duct and the refrigerant in the second duct diffuses into the container. An X-ray high voltage apparatus characterized by the above. An X-ray which is obtained by applying an output DC high voltage of the X-ray high-voltage apparatus according to claim 1 to an X-ray tube and irradiating the subject with X-rays emitted from the X-ray tube. Diagnostic imaging device.

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