JPH0441611B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is a CT scanner in which an external power source is connected to an X-ray tube attached to a rotating frame via a support column via a slip ring. The present invention relates to a high voltage power supply device that applies voltage.

(Prior Art) In a conventional CT scanner, a high voltage power supply device that applies high voltage from an external power supply to an X-ray tube attached to a rotating mount via a support column via a slip ring is a mount. A high-voltage slip-ring system that transmits the high voltage (70 kV on each side of the cathode and anode of the X-ray tube) generated by a high-voltage generator installed externally to the rotating frame via a high-voltage slip ring, and the frame. A low voltage (e.g. 200 to 400 V) is applied to the rotating frame from the low voltage part of the externally installed high voltage generator via the low voltage slip ring.
There is a low-pressure slip-ring system that transmits

(Problem to be solved by the invention) However, in the former high-pressure slip ring method, the voltage at the slip ring part is high, so gas insulation or oil insulation is required in consideration of withstand voltage, but the slip ring is sealed from the insulating medium. It is difficult to do so, and the slip ring itself must have a special structure, making it expensive.

In addition, in the latter low-voltage slip-spring method, a high voltage generator such as a transformer must be mounted on the rotating pedestal, so the pedestal itself must be large in order to withstand the weight. Furthermore, when a large current (for example, 50 to 200 A) is passed through the slip ring from the low-pressure part, the amount of power generated from the slip ring is large, so it is necessary to provide a separate heat exchanger to cool the heat generating part.

The present invention does not require insulation of the slip ring part, and is small and inexpensive, and can reduce the loading weight of the rotating frame and apply high voltage to the X-ray tube.
The purpose is to provide high voltage power supply equipment for CT scanners.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above objects, the present invention applies a high voltage from an external power source to an X-ray tube supported on a rotating frame via a slip ring. In the high-voltage power supply device of the CT scanner, a voltage transformer is installed at the fixing part of the rotating mount or outside the mount to step up the external power supply voltage to medium voltage, and the rotating mount is equipped with a voltage multiplier circuit consisting of a combination of a capacitor and a diode. Equipped with a voltage generator, the voltage obtained from the voltage transformer is transmitted to the rotating frame side via a slip ring, and is converted into a high voltage by a high voltage generator consisting of a voltage multiplier circuit using a combination of the capacitor and diode. The X-ray tube is configured to apply the same to the X-ray tube.

(Function) Therefore, in the case of the high voltage power supply device of the CT scanner having such a configuration, since the medium voltage is transmitted from the external power source through the voltage transformer to the rotating frame side, the withstand voltage is high for the slip ring part. There is no need to provide insulation that takes into account cooling, and the slip ring itself does not need to have a special structure that takes cooling into consideration, making the slip ring simple and inexpensive. In addition, the high voltage generator mounted on the rotating mount uses a voltage multiplier circuit consisting only of diodes and capacitors to apply high voltage to the X-ray tube, so the loading weight of the rotating mount is light. , it becomes possible to make the entire device smaller and cheaper.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram showing an example of the overall system configuration of a high voltage power supply device for a CT scanner according to the present invention. In FIG. 1, reference numeral 1 denotes an X-ray tube supported by a rotating mount (not shown) of a CT scanner via a support column. Further, 2 is an external AC power supply, 3 is a rectifier stack that converts the AC output obtained from the external AC power supply 2 into DC, and 4 and 5 are the rectifier stacks that convert the output converted into DC by the rectifier stack 3 into AC of a predetermined frequency. These are inverters corresponding to the cathode side and the anode side of the X-ray tube 1 to be converted. 6 is an AC output (for example,
200V) to a medium voltage (for example, 1 to 20kV), and the secondary output of this voltage transformer 6 can be collected by a slip ring 7 on the side of a rotating frame (not shown). In this case, the rectifier stack 3, the cathode side inverter 4, the anode side inverter 5, and the voltage transformer 6 are installed at a fixed part of the rotating frame or outside the frame, respectively. On the other hand, reference numerals 8 and 9 are voltage multiplier circuits mounted on the rotating frame side, such as high voltage generators consisting of Kotsukuroft-Walton circuits, and these high voltage generators 8 and 9 are composed of diodes and capacitors as shown in FIG. This is a bridge circuit in which multiple stages of bridge circuits are provided and connected as shown in the figure, and the secondary side output (for example, 5 kV voltage) of the voltage transformer 6 whose input side is collected via the slip ring 7 is When this is applied, a high voltage (for example, 60 to 70 kV) necessary for X-ray generation is generated and applied to the cathode and anode of the X-ray tube 1 from the output side.

As described above, in this embodiment, a rectifier stack 3 that converts the output of the AC power supply 2 into DC, and an inverter that converts the DC obtained from the rectifier stack 3 into AC of a predetermined frequency are installed on the fixed part of the rotating gantry of the CT scanner or on the outside of the gantry. 4 and 5, and a voltage transformer 6 that boosts the output of these inverters 4 and 5 to medium voltage (1 to 20 kV) is installed, and the secondary side output of this voltage transformer 6 is connected via a slip ring 7 (not shown). The secondary output of the voltage transformer 6, which is collected by the slip ring 7, is input to the rotating mount to generate the high voltage (e.g. 60~
The system is equipped with high voltage generators 8 and 9 consisting of Kotsukucroft-Walton circuits that generate 70kV).

Therefore, the voltage applied to the slip ring 7 is a medium voltage of 1 to 20 kV, and there is no need to consider insulation for the slip ring 7 to withstand voltage, unlike in conventional high voltage slip ring systems. Seals are also no longer required. In addition, in the case of the conventional low-pressure slip ring method (200 to 400 V), a large current (approximately 50 to 200 A) flows through the slip ring 7, so it is necessary to install a heat exchanger to cool the slip ring part. In the case of medium pressure, the current is about 1/10 of that in the case of low pressure, so there is no need to cool the slip ring, making the slip ring simple and inexpensive.

In addition, the high voltage generators 8 and 9, which are made up of Kotsukucroft-Walton circuits and are mounted on the rotating mount, have a configuration that combines diodes and capacitors, so they are small and lightweight (can be realized at about 30 kg), and the rotating mount can be It can be installed without being particularly large.

As a result, the entire high-voltage power supply system of the CT scanner can be made smaller and economically advantageous.

In the above embodiment, a case was described in which a Kotscroft-Walnton circuit was used as the voltage multiplier circuit, but recently, a voltage multiplier circuit using a combination of a capacitor and a diode has been proposed, for example, by the Institute of Electronics and Communication Engineers, September 11, 1985. There are many configurations as announced in ``About a new voltage doubler rectifier circuit'', and the same implementation as described above can be performed using these circuits. FIG. 3 shows an example of one of the circuit configurations.

[Effects of the Invention] As described above, according to the present invention, there is no need to insulate the slip ring part, and the loading weight of the rotating frame is reduced, and a high voltage can be applied to the X-ray tube. It is possible to provide an inexpensive high voltage power supply for a CT scanner.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing an embodiment of a high voltage power supply device for an X-ray CT scanner according to the present invention, and Fig. 2 shows a high voltage generator using a Cockcroft-Walton circuit as a voltage multiplier circuit in the same embodiment. FIG. 3 is a wiring diagram showing other configuration examples of the voltage multiplier circuit. 1... X-ray tube, 2... AC power supply, 3... Rectifier stack, 4, 5... Inverter, 6... Voltage transformer, 7... Slip ring, 8, 9... From Kotscroft-Walton circuit A high voltage generator.

Claims (1)

[Claims] 1. In a high voltage power supply device for a CT scanner that applies high voltage from an external power source to an X-ray tube supported on a rotating pedestal via a slip ring, the external power supply voltage is boosted to medium voltage at the rotating pedestal fixing part or outside the gantry. The rotating frame is equipped with a high voltage generator consisting of a voltage multiplier circuit made up of a combination of a capacitor and a diode, and the voltage obtained from the voltage transformer is transmitted to the rotating frame via a slip ring. A high voltage power supply device for a CT scanner, characterized in that a high voltage generator comprising a voltage multiplier circuit using a combination of the capacitor and the diode converts the voltage into a high voltage and applies it to the X-ray tube.