JP2002164197A - X-ray generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray generator capable of simply and more exactly detecting a tube current even in an X-ray generator using a grounded-plate X-ray tube. SOLUTION: DC voltage outputted from a high voltage generator which generates DC high voltage is supplied to a grounded-plate X-ray tube to emit X-rays. A tube current detecting loop is provided between a positive terminal and an earth terminal of the high voltage generator of the X-ray generator, and a current flowing in the tube current detecting loop is detected to detect a current flowing in the grounded-plate X-ray tube. The current flowing in the tube current detecting loop is detected by providing a Hall element type current detector, a resistor, which detects voltage drop, or the like in this loop, and the value detected by these is amplified to detect the tube current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray generator using a grounded anode X-ray tube, and more particularly, to a device capable of easily detecting a current flowing through the X-ray tube (hereinafter referred to as a tube current). X-ray generator.

[0002]

2. Description of the Related Art An X-ray generator is used to apply X-rays to a diagnosis site of a subject.
An X-ray tube that emits X-rays for irradiating X-rays, and a high-voltage generator that generates a DC high voltage (hereinafter, referred to as a tube voltage) applied to the X-ray tube; Consists of The high voltage generator is based on JIS Z4702 (Japanese Industrial Standards Committee: General rules for medical X-ray high voltage equipment, published by Japan Standards Association, 19
As described in (September 27, 1999), a neutral voltage high voltage generator has been mainly used. X-ray high-voltage equipment is tested according to the test method described in JIS Z 4702, and the error of tube voltage and tube current is ± 10% each.
Below, it is determined to be ± 20% or less.

On the other hand, with the increase in capacity and withstand voltage of the X-ray generator, for example, a grounded anode X-ray tube described in Japanese Patent Application Laid-Open No. 08-315758 has been used. . With the anode grounded X-ray tube, by grounding the rotating rotor of the anode, the degree of freedom in designing the anode is increased, the heat radiation design is facilitated, and the heat radiation efficiency can be drastically improved. Therefore, a large-capacity X-ray tube becomes possible.

[0004]

SUMMARY OF THE INVENTION As described above,
The measurement of the tube current is determined based on the tube current characteristics test method of JIS Z 4704, and measures the current flowing through the high voltage cable on the anode side or the current flowing on the ground side of the high voltage rectifier on the anode side. Is supposed to.

However, the anode-side cable does not exist in the anode grounded X-ray tube, and it is impossible to measure the tube current.
The cathode has a DC current of several mA to 1A, and several A to
Since an AC filament current of several tens A flows, it is difficult to accurately measure the current. Further, in order to calibrate the tube current, the measuring device needs to be independent of the device.

Accordingly, the present invention solves the above-mentioned problems of the conventional apparatus, and provides an X-ray generator capable of easily and more accurately measuring a tube current even in an anode grounded X-ray tube. The purpose is to:

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a high voltage generator for generating a DC high voltage, and a grounded anode X-ray tube which emits X-rays when the DC voltage of the high voltage generator is applied. In the X-ray generator, a tube current detection loop is provided between the anode side terminal of the high voltage generator and the ground terminal, and a current flowing through the tube current detection loop is detected so that the anode grounded X-ray tube is provided. This is achieved by detecting the flowing current. The current flowing in the tube current detection loop is configured to detect a Hall element type current detector, a resistor that generates a voltage drop, and the like in the loop, amplify the detected value, and detect the tube current.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of the overall configuration showing an embodiment of an X-ray generator according to the present invention. This X-ray generator irradiates a diagnostic site of a subject with X-rays. As shown in FIG. 1, a high-voltage generator 1 that generates a DC high voltage;
An anode grounded X-ray tube 2 for applying an output voltage of the high voltage generator 1 to irradiate X-rays.

The high-voltage generator 1 of this embodiment is connected to a commercial AC power supply 10 and converts a voltage of the AC power supply 10 into a DC voltage. A capacitor 102 smoothes an output voltage of the converter 101. An inverter 103 that converts this DC voltage into a high-frequency AC voltage; a high-voltage transformer 104 that boosts the high-frequency AC voltage; a high-voltage rectifier 105 that rectifies the output voltage of the high-voltage transformer 104; A tube current detection loop 110 is connected to the positive output and one is connected to ground (ground), and the negative output of the high voltage rectifier 105 is connected to the cathode (cathode) terminal of the anode grounded X-ray tube. . The X-ray tube 2 includes a filament 201 and a rotating anode 202, and the filament 201 serves as a cathode (cathode) terminal.
Connect to line generator. The rotating anode is the anode (anode) and is connected to earth (ground). This anode grounded X-ray tube rotates with a large surface area and volume for heat dissipation, but since the anode is grounded, the withstand voltage design is easy and heat transfer directly to a metal chassis with a large heat capacity. By contacting a highly efficient metal, the heat capacity of the anode can be dramatically increased.

Reference numeral 3 denotes a tube voltage / tube ammeter which is connected only at the time of calibration in order to calibrate the high voltage generator 1. The tube voltage / tube ammeter 3 for the anode grounded X-ray tube detects the voltage between the anode and the earth (AE), that is, the tube voltage by the voltage divider 302, and outputs the tube voltage V ₍ via the amplifier 303 (a). _AC) is output or displayed. Further, the tube current is detected by the Hall element type current detector 301 connected to the tube current detection loop 110,
The tube current I _(A) is output or displayed via the amplifier 303 (b).

The present invention provides a tube current detecting means. According to the present embodiment, the anode 202 of the X-ray tube 2 is provided.
The current flowing from the ground connected to the X-ray tube 2 flows to the anode 202 and the cathode 201 of the X-ray tube 2 (tube current), and the high voltage generator 1
Of the tube current flowing into the high-voltage rectifier 105 and flowing to the ground through the tube current detection loop 110. To be

The tube voltage and tube current errors of the medical X-ray generator are determined to be ± 10% or less and ± 20% or less according to JIS Z 4702, respectively. It is stipulated that calibration be performed.

The tube voltage / tube ammeter 3 for calibrating the high-voltage generator 1 has a form that can be easily removed because it is connected only when performing calibration, and is usually used for relaying a high-voltage cable. And the tube voltage / tube current is measured. The tube voltage / tube ammeter according to the present invention can easily detect the tube current by detecting the current of the tube current detection loop 110 provided outside the high-voltage generator, in addition to the tube voltage measurement method similar to the conventional one. Can be measured.

The tube current detection loop 110 in the present embodiment
Is connected to the positive output of the high-voltage rectifier 105 by wiring and only one is connected to the ground (ground), but the tube current is detected by the Hall element type current detector 301 of the tube voltage / tube ammeter 3. Because it is possible, it can be detected in a non-contact manner, and since the potential is near the ground, handling is easy.

FIG. 2 shows a main part of an X-ray generator according to a second embodiment of the present invention. The tube current detection loop 110 and the tube ammeter of the tube voltage / tube ammeter 3 in the first embodiment. Only shown.

In this embodiment, a current detecting resistor 111 is inserted in the tube current detecting loop 110. When the tube current flows, a voltage is generated across the resistor 111. The tube ammeter is
The tube current is measured by measuring this voltage.

A current detecting resistor 111 is connected to the tube current detecting loop 110.
, The current detecting means of the tube ammeter can be made simpler, and more accurate and have good high-frequency characteristics.

FIG. 3 shows a main part of an X-ray generator according to a third embodiment of the present invention. The tube current detecting loop 110 and the tube ammeter of the tube voltage / tube ammeter 3 in the first embodiment. Only shown. This example corresponds to the current detection resistor 11 in the second embodiment.
1 is replaced with a plurality of current detecting resistors 304 incorporated in the tube ammeter, and a gain switch 306 is provided so that the measurement gain can be switched according to the magnitude of the tube current.

In this embodiment, an accurate tube current can be obtained, and a good tube current waveform can be obtained in a wide range of several mA to several A by a plurality of current detecting resistors and gain switches. Can be. However, since the tube voltage / tube ammeter is connected and calibrated only when calibrating the tube voltage and tube current, it is not always connected. Need to work. As described above, in a state where there is no tube current detection loop other than at the time of calibration, the anode end is open, and there is a risk of outputting a high voltage.Therefore, in order to prevent overvoltage, the voltage limiting means 112, in this example, a zener diode is used. It is inserted between the anode terminal and the ground terminal to form a loop through which current flows.

FIG. 4 shows a main part of an X-ray generator according to a fourth embodiment of the present invention, in which the tube current detection loop 110 and the tube ammeter of the tube voltage / tube ammeter 3 in the first embodiment are shown. Only shown.

In this embodiment, in the first embodiment, the ground end of the current detection loop is connected to the inside of the tube ammeter, so that the tube ammeter can be easily connected. Also in this example, as in the third embodiment, the voltage limiting means 112 for preventing an overvoltage is essential, and a loop in which a current flows between the anode terminal and the ground is formed. In this example, the tube ammeter has a structure using the Hall element type current detector shown in the first embodiment, but it may have a structure using a current detection resistor as shown in the third embodiment. Good.

Although FIG. 1 shows an inverter type high voltage device, the same applies to all types of X-ray high voltage devices. A current detection loop is provided between the positive output of the high voltage transformer and the ground terminal. This can be realized by providing

[0024]

As described above, the tube current detection loop extending from the anode side terminal of the high voltage generator to the ground terminal is provided to detect the tube current flowing through the X-ray tube. Since it is possible, it is easy to measure the tube current even in an X-ray generator using an anode grounded X-ray tube, and it is possible to irradiate X-rays while confirming that the tube current is accurate. A line generator can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of an overall configuration showing a first embodiment of an X-ray generator according to the present invention.

FIG. 2 is a diagram showing a main part of an X-ray generator according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a main part of an X-ray generator according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a main part of an X-ray generator according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... High voltage generator, 2 ... X-ray tube, 3 ... Tube voltage / tube ammeter, 1
0 ... commercial AC power supply, 101 ... converter, 102 ... capacitor, 103 ... inverter, 104 ... high voltage transformer, 105 ... high voltage rectifier, 110 ... tube current detection loop, 111 ... shunt resistor, 112 ... voltage limiting means, 201 ... Cathode filament, 202
... Rotating anode, 301 ... Current detector, 302 ... Voltage divider, 303 ... Amplifier, 304 ... Shunt resistor, 305 ... Switcher

Claims (1)

[Claims] 1. A high voltage generator for generating a DC high voltage;
An X-ray generator comprising an anode grounded X-ray tube that emits X-rays when a DC voltage of the high voltage generator is applied,
Providing a tube current detection loop between the anode terminal and the ground terminal of the high voltage generator, detecting a current flowing through the tube current detection loop and detecting a current flowing through the anode grounded X-ray tube. Characteristic X-ray generator.