JPH01177873A - High voltage power unit for ct scanner - Google Patents

Abstract

PURPOSE:To miniaturize a unit, and to reduct cost thereof by transmitting power to the rotary frame side as intermediate voltage through a voltage transformer from an external power. CONSTITUTION:A high voltage power for a CT scanner is composed of an X ray tube 1, an external AC power 2, a rectifier stack 3, inverters 4-5, a voltage transformer 6, etc., boosting AC outputs (200V) from the inverters 4-5 to intermediate voltage (1-20kV). A secondary side output from the voltage transformer 6 is collected by the rotary frame side by a slip ring 7. The rectifier stack 3, the cathode side inverter A4 and the anode side inverter 5 and the voltage transformer 6 are installed respectively to a fixing section for a rotary frame or outside the frame at that time. On the other hand, high voltage generators 8-9 consist of voltage multiplying circuits (Cockcroft-Walton circuits) loaded to the rotary frame side, and a secondary side output from the voltage transformer 6 collect ed through the slip ring 7 is applied to an anode and a cathode for the X-ray tube 1 from the output side as high voltage when the secondary side output is applied respectively to the input sides.

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, an X
The high voltage power supply device that applies high voltage to the X-ray tube is a high voltage generated from a high voltage generator installed outside the gantry (70 kV on one side of the cathode and anode of the X-ray tube).
There is a high-pressure slip ring method in which the voltage is transmitted to the rotating frame side via a high-voltage slip ring, and a low voltage (e.g. 200~400V)
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 system, 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 ring method, a high voltage generator such as a transformer must be mounted on the rotating frame, so the frame itself must be large to withstand the weight. When a large current (for example, 50 to 20 OA) is passed through the slip ring from the low-pressure part, the slip ring generates a large amount of heat, so it is necessary to provide a separate heat exchanger to cool the heat generating part.

To provide a small and inexpensive high voltage power supply device for a CT scanner that does not require insulation of a slip ring part, reduces the loading weight of a rotating frame, and can apply high voltage to an X-ray tube. With the goal.

[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 a high-voltage power supply device for a CT scanner, a voltage transformer is installed at the fixed 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 transformer that boosts the external power supply voltage to medium voltage. 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 high voltage power supply device of the CT scanner having such a configuration, since medium voltage is transmitted from the external power source through the voltage transformer to the rotating frame side, withstand voltage must be taken into account for the slip ring part. There is no need to provide additional insulation, 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 embodiment 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. 1st
In the figure, reference numeral 1 denotes an X-ray tube supported by a rotating pedestal (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 outputs converted to DC by the rectifier stack 3, respectively, 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 converts the AC outputs (for example, 200V) obtained from the cathode side inverter 4 and the anode side inverter 5 to medium voltage (for example, 1 to 20kV) 1. : A voltage transformer that boosts the voltage, and the secondary output of this voltage transformer 6 is connected to a slip ring 7.
This makes it possible to collect current on the rotating stand side (not shown).

In this case, the rectifier stack 3. Cathode side inverter 4 and anode side inverter 5. The voltage transformer 6 is installed at a fixed portion of the rotary frame or outside the frame. On the other hand, 8 and 9
1 is a high-voltage generator, which is made up of a voltage multiplier circuit 1 mounted on the rotating frame side, such as a Kotscroft-Walton circuit, and these high-voltage generators 8 and 9 are bridges that combine diodes and capacitors as shown in Figure 2. The circuit is constructed in multiple stages and wired as shown in the figure, and when the secondary side output (for example, 5 kV voltage) of the voltage transformer 6, which collects the current through the slip ring 7, is applied to the input side of the circuit, this X
A high voltage (for example, 60 to 70 kV) necessary for ray generation is generated and applied to the cathode and anode of the X-ray tube 1 from the output side.

Thus, in this embodiment, a rectifier stack 3. Inverters 4 and 5 convert the direct current obtained from this rectifier stack 3 into alternating current of a predetermined frequency, and the outputs of these inverters 4 and 5 are
), and the secondary output of the voltage transformer 6 is transmitted to the rotating stand (not shown) via a slip ring 7, and the slip ring 7 collects current on the rotating stand. Input the secondary side output of the voltage transformer 6
The system is equipped with high voltage generators 8 and 9 consisting of Kotscroft-Walton circuits that generate the high voltage (for example, 60 to 70 kV) necessary for line generation.

Therefore, the voltage applied to the slip ring 7 is between 1 and 20
At a medium pressure of kV, there is no need to consider insulation for the slip ring 7 to withstand voltage, as in the conventional high-pressure slip ring system, and there is no need to seal an insulating medium. In addition, the conventional low pressure slip ring method (200 to 40
0V), a large current (50~2V) is applied to the slip ring 7.
00A), so it is necessary to install a heat exchanger to cool the slip ring.However, in the case of medium pressure, the current is about 1/10 of that in the case of low pressure, so the slip ring There is no need for cooling, making the slip ring simple and inexpensive.

In addition, the high voltage generator 8.9, which consists of a Kotsukucroft-Walton circuit mounted on the rotating mount, has a configuration that combines a diode and a capacitor, so it is small and lightweight (can be realized at about 30 kg), and the rotating mount is 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-Walton circuit was used as a 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 for insulation of 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 device for a CT scanner.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram showing an embodiment of a high voltage power supply device for an X1JCT scanner according to the present invention, and Fig. 2 shows details of a high voltage generator using a Kotscroft-Walton circuit as a voltage multiplier circuit in the same embodiment. FIG. 3 is a wiring diagram showing another example of the configuration 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 ... A high voltage generator consisting of a Kotsukucroft Walton circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (1)

[Claims] 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. A voltage transformer is provided, and the rotating frame is equipped with a high voltage generator consisting of a voltage multiplier circuit using 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 the high voltage is converted into a high voltage and applied to the X-ray tube by a high voltage generator comprising a voltage multiplier circuit using a combination of the capacitor and the diode.