JPH056800B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field This invention relates to a tube current control circuit for a pulse X-ray fluoroscope. (B) Prior art A pulsed X-ray fluoroscopy device emits X-rays in a pulsed manner, stores a fluoroscopic image obtained by the pulsed X-rays in a video memory device, and detects the difference between pulsed X-rays. During the period, the pre-pulse X-ray images stored in the video memory device are displayed on a TV monitor so that they can be observed as continuous fluoroscopic images, reducing the patient's exposure dose. It is also extremely effective in expanding fluoroscopy ability using high-power pulsed X-rays, especially for surgical X-rays.
It is useful as a line device. By the way, the interval between these pulsed X-rays, or the pulse rate (normally the number of pulses per second; expressed as P/S), needs to be optimized for the examination depending on the part to be examined of the patient. However, even if this pulse rate is fixed or variable, the fluoroscopy conditions, that is, the tube voltage and tube current of the X-ray tube are fixed, making it difficult to use. In addition, although it is possible to manually set the fluoroscopy conditions, the disadvantage is that the operation is complicated and inefficient. (C) Purpose This invention can control the pulsed X-rays to automatically generate the maximum tube current considering the X-ray tube load factor using the set pulse rate and tube voltage, thereby improving inspection efficiency and It is an object of the present invention to provide a tube current control circuit for a pulsed X-ray fluoroscope that can improve the fluoroscopy ability. (D) Configuration The tube current control circuit of the pulsed X-ray fluoroscope according to the present invention generates a signal regarding the optimal tube current in consideration of the maximum load characteristics of the X-ray tube for each combination with the set tube voltage for pulsed X-rays. The present invention is characterized in that, in response to input of the pulse rate setting signal and tube voltage setting signal, a discriminating circuit is arranged to output a signal regarding the optimum tube current corresponding to the combination thereof. (E) Example Generally, the maximum load curve of an X-ray tube is expressed as shown in Figure 1. In a pulse fluoroscope, if the pulse width of one pulse is constant, each pulse is represented by a different curve depending on the pulse rate. If the values of the pulse rate P/S, tube voltage KV, and tube current mA are selected according to FIG. 1, the X-ray tube will be utilized to the maximum. Therefore, as shown in FIG. 2, the tube voltage setting signal generated from the tube voltage setting circuit 1 and the pulse rate setting signal from the pulse rate setting circuit 2 are input to the discrimination sequence circuit 3. The optimum tube current corresponding to the tube voltage setting signal and the pulse rate setting signal is selected at , and the selection signal is sent to the tube current setting circuit 4. The tube voltage KV and pulse rate P/S are usually manually set on the control panel of the X-ray high voltage device, and are set to values in the range of 40 to 100 KV and 3 to 0.25 P/ST, respectively. In this embodiment, the tube voltage setting circuit 1 sets this range to 40 to 49, 50 to 59, 60, for example.
~69,...6 ranges from 90 to 100KV, and a signal indicating which of them corresponds to the set tube voltage is output. On the other hand, the pulse rate setting circuit divides the above pulse rate range into, for example, 0.25, 0.5, 1, 1.5, 2, 2.5, and 3, and determines which of them it corresponds to. The signal is sent to the discrimination sequence circuit 3. The discrimination sequence circuit 3 is configured by, for example, as shown in FIG. Only the NAND circuit 5 at the point where the tube voltage line and the pulse rate line intersect produces a "0" output. And each output 1 of a large number of NAND circuits 5
1, 12, ...21, 22, ... are the maximum tube currents m allowed for each combination of tube voltage and pulse rate.
The current is input to each of the tube current setting circuits 4 set to be A. In this example, mA is 2, 3,
4, . . . 10, and the tube current setting circuit 4 includes nine tube current settings, each of which is set to the nine types of mA. According to each combination of tube voltage KV and pulse rate P/S thus set, tube current mAG as shown in the following table is obtained. In addition, as shown in this table, P/S; 0.5,
KV; 40-49, P/S; 0.25, KV; 50
~59, it will be the same 9mA, so output 1
2 and 2 are connected to the same tube current setting circuit.

[Table] Note that in the above embodiment, the tube voltage setting was manually established on the control device panel, but automatic setting may also be used. All you have to do is enter 3. In the case of pulse X-ray fluoroscopy equipment with IBS (TV brightness automatic adjustment system), the tube voltage is automatically set to the lowest KV, while the tube current is automatically set to the maximum mA with the tube current control described above. ,
A fluoroscopic image with good contrast due to maximum mA and KV is automatically obtained. (C) Effect According to the tube current control circuit of the pulsed X-ray fluoroscope of the present invention, the discrimination circuit determines the current of the X-ray tube for each combination of the set pulse rate for pulses and X-rays and the set tube voltage. Since it holds a signal regarding the optimal tube current that takes into account the maximum load and characteristics, once the pulse rate and tube voltage are set, this discrimination circuit will determine the optimal tube current corresponding to the combination of that pulse rate and tube voltage. Since the optimum tube current is automatically set based on the output signal, it is easy to use without any troublesome operation, and the inspection rate is improved. Further, since pulsed X-rays are always emitted at the maximum tube current of the X-ray tube load factor, it is possible to use an efficient pulsed X-ray fluoroscope.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the maximum load curve of the X-ray tube, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is a block diagram showing one specific circuit example of the discrimination sequence circuit 3 of FIG. 2. 1...Tube voltage setting circuit, 2...Pulse rate setting circuit, 3...Discrimination sequence circuit, 4...Tube current setting circuit, 5...NAND circuit.

Claims (1)

[Claims] 1. Exposing X-rays in a pulsed manner and storing a fluoroscopic image obtained by the pulsed X-rays in a video memory device,
The period between the pulsed X-rays is determined by the pulsed A signal related to the optimum tube current is held in consideration of the maximum load characteristics of the X-ray tube for each combination of the set pulse rate and the set tube voltage, and the pulse rate setting signal and tube voltage setting signal are input. A tube current control circuit characterized by comprising a discrimination circuit that outputs a signal regarding an optimum tube current corresponding to a combination thereof depending on the combination of the tube currents.