JPS6233720B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray apparatus equipped with a detector for detecting the amount of radiation emitted from an X-ray tube.

In a conventional X-ray apparatus, as shown in the block diagram of FIG. 1, a high voltage generator 2 is driven based on a signal from an X-ray controller 1.
X-rays are emitted from the X-ray tube 3 by applying high voltage, and the radiation is transmitted through the subject 7 placed on the top plate 8 via the movable aperture device 6, and the amount of transmitted X-rays at this time is calculated. The X-ray imaging system 9 converts the signal into a video signal to perform a desired diagnosis.
At this time, an ionization chamber type flat radiation detector 4, for example, is placed on the subject 7 side of the aperture device 6, and the output X-ray dose is measured by this detector 4, and the result is transmitted as a detection signal, for example. The signal is appropriately processed in the processing unit 5 and displayed and recorded in the X-ray dose monitor circuit 12, and when the value reaches a predetermined value or more, a warning signal is generated and applied to the X-ray controller 1 to start X-ray exposure. stop,
This prevented the exposure dose to patients from becoming excessive.

However, since this detector 4 uses a free air type ionization chamber radiation detector that is not isolated from the outside air, it is easily affected by external environmental conditions (particularly humidity). ,
There were problems such as the need for a high-voltage power supply to operate the detector. Furthermore, when used in combination with a movable diaphragm with a light emitter, the outer circumference and electrodes of the detector must be transparent so as not to interfere with the use of the emitter, which increases manufacturing costs. This caused problems such as design constraints.

The present invention has been made in view of the above circumstances, and is inexpensive and unaffected by environmental conditions.
An object of the present invention is to provide an X-ray device equipped with a ray detector.

The present invention will be specifically explained below using Examples.

FIG. 2 is a block diagram showing an example of the X-ray apparatus of the present invention. In the figure, 1 is an X-ray controller,
2 is a high voltage generator driven by the output signal of the X-ray controller 1, 3 is an X-ray tube controlled by the high voltage generator 2, and 6 is an X-ray movable aperture device. 7 is a subject placed on the top plate 8, and 9 is an X-ray imaging system. In the present invention, in particular, a semiconductor radiation detector 4 is disposed at the radiation opening of the X-ray tube 3, that is, at the connection between the X-ray movable aperture device 6 and the X-ray tube 3, and its output terminal is connected to the detection signal processing section. The output terminal of the detection signal processing section 5 is connected to the input terminal of the X-ray dose monitor circuit 12. Such detectors 4 and
A specific example of the relationship between the ray tube 3 and the X-ray movable aperture device 6 is shown in FIG. As shown in the figure, the X-ray tube 3 is composed of an anode 3-1 and a cathode 3-2, and the X-ray movable diaphragm device 6 attached to the bottom of the tube consists of multistage blades arranged in three stages, upper, middle, and lower. 6-1, light source 6-3
and a light projector consisting of a mirror 6-2. A detection unit 10 and a preamplifier 11 (feedback resistor R ₁
A semiconductor radiation detector consisting of an operational amplifier (with an operational amplifier) is installed. The detection unit 10 of this semiconductor radiation detector is constituted by, for example, a surface barrier semiconductor element used in a non-biased state, and there is
When a radiation is incident, an output electrical signal proportional to the incident X-ray dose is output, and the electrical signal is sent to the preamplifier 11.
It will be amplified by This situation can be seen in the fifth
This will be explained in more detail with reference to the characteristic diagram shown in the figure. The figure shows the logarithm of the X-ray dose rate (R/min) on the horizontal axis and the logarithm of the output voltage of the preamplifier on the vertical axis (here, the feedback resistance R ₁ is measured as 10KΩ). did). As is clear from the figure, it will be understood that the semiconductor detection element 10 generates an output electrical signal proportional to the dose over a wide range of incident X-ray doses.

By the way, since the distances of the subject 7 and the detection element 10 from the X-ray tube focal point 3-3 are different, the amount of X-rays incident between them also differs according to the inverse square law.
Regarding this, it is usually expressed as the product R・S of unit area S and dose R (hereinafter referred to as area dose).
Regardless of the position of the detection element 10, the detection element 1
It is only necessary to obtain the effective detection area of 0. still,
The detection element 10 is surrounded by electrical and optical shielding. Additionally, due to the characteristics of semiconductor devices, as the area increases, the stray capacitance also increases, leading to deterioration of the rising characteristics of the detected waveform.
When the detection element 10 is disposed at the radiation opening of -3, a relatively small area is sufficient, and the rising characteristics of the detected waveform will not deteriorate. Such a semiconductor detection element 10 is made of a silicon plate having a thickness of about 300 to 500 μm.

The output of the semiconductor detector 4 described above is applied to a detection signal processing unit 5 having a configuration as shown in FIG.
displayed and monitored. That is, as shown in the figure, in the detection signal processing section 5, the output of the preamplifier 11 of the detector 4 is amplified by an inverting amplifier consisting of an input resistor _R2 , a feedback resistor _R3 , and an operational amplifier _OP2 .
It is integrated by an integrator consisting of an operational amplifier OP ₃ , a resistor R ₄ , a relay R _y1 , and a capacitor C ₁ , and is introduced into the X-ray dose monitor circuit 12 via a voltage follower consisting of an operational amplifier OP ₄ and displayed on the display DS. . In the X-ray dose monitor circuit 12, the output of the operational amplifier _OP4 is introduced into a comparison operational amplifier _OP5 via an input resistor _R5 , and is compared with _a reference voltage _E.sub.S. to drive the lamp or buzzer LM. At the same time, the output of the operational amplifier _OP5 is sent to the X-ray exposure interlock circuit of the X-ray controller 1.

Such an X-ray device is used in the following manner.

First, X-ray exposure (radiation) conditions are set by the X-ray controller 1 and the high voltage generator 2, and the X-ray tube 3
X-rays are emitted from the This X-ray dose is detected by a semiconductor detector 4 installed at the radiation port, converted into an electrical signal, and input to the detection signal processing section 5. This detection signal processing section 5 converts the detected electric signal into an inverting amplifier.
After amplification by OP ₂ , R ₂ , R ₃ , integrator OP ₃ , C ₁ ,
It is integrated by R ₄ and R _y1 and output via the voltage follower OP ₄ , and is recorded or displayed as an area dose value on the display DS in the X-ray monitor circuit 12, and the value is also displayed on the comparison operational amplifier OP ₅ . When becomes equal to or higher than the reference voltage E _S corresponding to a predetermined X-ray dose or X-ray dose rate value, a warning signal is output from the operational amplifier OP ₅ , and the lamp or bougie LM is driven via the transistor Tr. It's becoming like that. When the output of the operational amplifier _OP5 is applied to the X-ray controller 1, an interlock circuit (not shown) is activated, and X-ray exposure is stopped. This makes it possible to prevent the radiation dose to the subject from becoming excessive. Incidentally, the integration time of the integrator and its timing are determined by the operation of the relay _Ry1 driven by the signal output from the X-ray controller 1.

Since the X-ray apparatus described above uses a combination of the semiconductor radiation detection element 10 and the amplifier 11 as a detector, it is not affected by environmental conditions. In addition, the semiconductor radiation detector 4 is used in a non-biased state, or even if a bias is applied, a very small voltage is sufficient, so it does not require a high-voltage power source as in the conventional case. Furthermore, even when combined with the movable diaphragm device 6 with a light projector as in the embodiment described above, since the detector is installed at the X-ray emission opening, the light projecting function of the projector will not be inhibited. Therefore, there is no need for the detector to be made of a transparent material as in the past, and since the detector is a small-area semiconductor radiation detector, the cost can be reduced and there are no restrictions on design.

In the above embodiment, the detection signal processing section 5
In the above, the detection signal is converted into an X-ray dose or an X-ray dose rate, and this is displayed or recorded in the X-ray dose monitor circuit 12, and a warning signal is generated. However, the present invention is not limited to this. It can also be applied to stabilize X-ray output.

That is, the output signal of the detection signal processing unit 5 (the output signal of the operational amplifier OP ₂ or the operational amplifier OP ₄ ) is fed back to the tube voltage control system of the X-ray controller 1, and as a result, the tube voltage is set and the X-ray output is obtained. Continuous control.

For example, a high voltage generator 2 as shown in FIG.
However, in a device using a phase control method using a thyristor SC to adjust the primary side voltage of the high voltage transformer HT, the output signal of the detection signal processing section 5 is given as the control signal of the well-known phase control circuit 1'. By doing so, the X-ray output of the X-ray tube 3 is stabilized at a predetermined value.

In addition, a high voltage generator 2 as shown in FIG. 7 inserts high voltage electron tubes (for example, tetrode tubes) TT ₁ and TT ₂ into the secondary side of a high voltage transformer HT, and generates voltage from the grid bias voltage generating circuit GG. In a system in which the internal resistance of the high-voltage electron tubes TT ₁ and TT ₂ can be variably controlled by appropriately controlling the grid bias voltage of the grid control circuit 1'', the tube voltage can be adjusted as a result. By giving the output signal of the detection signal processing section 5 to the grid control circuit 1'' as a control signal for the grid bias voltage of the high-voltage electron tubes TT ₁ and TT ₂ , the X-ray output can be stabilized in the same manner as described above. It is possible.

According to the present invention described in detail above, an X-ray detector equipped with an X-ray detector that is inexpensive and unaffected by environmental conditions.
line equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional X-ray device, FIG. 2 is a block diagram showing an example of the X-ray device of the present invention, and FIG. 3 is a cross-sectional diagram showing an example of the arrangement of the detectors. 4 is a block diagram showing an example of a specific configuration of the detector control section, FIG. 5 is a characteristic diagram of a semiconductor radiation detector, and FIGS. 6 and 7 are block diagrams showing an example of a specific configuration of the detector control section. FIG. 2 is an electric circuit diagram showing an example when used to stabilize X-ray output. 1...X-ray controller, 2...High voltage generator, 3...X
Wire tube, 4...detector, 5...detection signal processing section, 6...X
Line movable aperture device, 7... Subject, 8... Top plate, 9... X
Ray imaging system, 12...X-ray dose monitor circuit.

Claims (1)

[Claims] 1. An X-ray tube device controlled by an X-ray controller, an X-ray movable aperture device that limits the irradiation field of X-rays emitted from this X-ray tube device, and an X-ray a semiconductor radiation detector disposed between a movable aperture device and a radiation opening of the X-ray tube device; a detection signal processing unit that converts a detection signal of the semiconductor radiation detector into an X-ray dose or an X-ray dose rate; An X-ray apparatus characterized in that the output signal from the detection signal processing section is used as an exposure dose measurement signal to a subject or a feedback signal to an X-ray output control system in an X-ray controller. . 2. The semiconductor radiation detector according to claim 1, wherein the semiconductor radiation detector has a surface barrier type structure that generates an electromotive force by X-rays and is used in a non-biased state. line equipment.