JPS6346559B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a condenser type X-ray apparatus that includes:
This invention relates to a device that calculates and displays the shooting time prior to actual shooting when setting KV (tube voltage) and mAS (discharged charge amount).

In a capacitor type X-ray device, the imaging conditions are set by setting the charging voltage with the KV setting device and the amount of discharge charge during X-ray exposure with the mAS setting device. It was not possible to know in advance how long the shooting would take. However, in actual X-ray photography, especially when imaging fast-moving areas, the exposure time is extremely important in the imaging conditions, so not being able to know this exposure time is extremely inconvenient. ing.

In view of the above, the present invention provides an imaging time pre-display device for a capacitor type X-ray device that immediately calculates the imaging time from the set values of KV and mAS according to the emission characteristics of the X-ray tube and displays it. The purpose is to

An embodiment of the present invention will be described below with reference to the drawings. First, the discharge characteristics of a high-voltage capacitor are as shown in Figure 1, and the initial voltage
Vn, the voltage after t seconds is V, and the time constant is An, which can be approximated by the following exponential function.

V=Vne ^-Ant Here, the discharge charge amount is set by setting mAS, so if the combined capacitance of the high-voltage capacitor is C, the discharge charge amount during actual X-ray exposure will reach mAS. What I did was mAS/C from Vn.
This means that the voltage drops by 10 seconds, so if this state is reached after t seconds, it can be expressed as V=Vn-mAS/C=Vne ^-Ant . Therefore, e ^Ant =Vn/Vn-mAS/C Ant=log e{Vn/Vn-mAS/C} An=1/tlog e{Vn/Vn-mAS/C}...(1) t=1/Anlog e {Vn/Vn-mAS/C}...(2) Equations (1) and (2) can be derived.

Therefore, as shown in FIG. 2, a CPU (arithmetic unit) 1 and a program memory 2 such as a P-ROM that stores the arithmetic program of equation (2) above are used to store battery backup CMOS-RAM and EP
- Based on the time constant An stored in the discharge time constant memory 3 such as ROM, input the KV and mAS setting values from the KV setting device 4 and mAS setting device 5 through the input ports 6 and 7 and ) calculation is performed, and the calculated imaging time t is displayed on the SEC display 9 via the output port 8. The discharge time constant An to be stored in the memory 3 needs to be determined for each tube, since the emission characteristics of the X-ray tube vary from tube to tube. For this reason, when individually adjusting the X-ray device, the time constant for the tube is measured for each sample value of charging voltage (for example, 10 KV). Specifically, for example, mAS is set such that mAS/C=1/2V, and the X-rays are actually exposed and the imaging time is actually measured using an imaging time meter or the like. Assuming that this actual measurement time is tn and the charging voltage is Vn, see (1) above.
Calculate the time constant An by substituting it into the formula. This is repeated by changing the charging voltage in increments of 10 KV, and the time constant An obtained in increments of 10 KV is stored in the memory 3. This memory 3 is for battery backup.
In the case of CMOS-RAM, write via input port 11 by digital switch 10, P-ROM
In this case, write using a P-ROM writer.

In this configuration, when the imaging conditions are set using the KV setting 4 and the mAS setting device 5, the set KV value and mAS value are read by the CPU 1 via the input ports 6 and 7, and the voltage closest to this KV value is read. The time constant An corresponding to Vn is read out from the memory 3, and the above equation (2) is calculated to calculate the photographing time t. That is, each time the imaging conditions are set, the imaging time is calculated and displayed on the SEC display 9 prior to actual X-ray exposure.

Note that in the above, the time constant is determined and stored every 10 KV, but this is an example of sampling, and the finer the sampling interval, the higher the precision is, and is therefore preferable.

As described above with respect to the embodiments, according to the present invention, it is possible to know the shooting time by setting the shooting conditions using the KV setting device and the mAS setting device. Conditions can be set, which is very effective when photographing parts that move quickly.

[Brief explanation of the drawing]

Figure 1 is a graph showing the discharge characteristics of a capacitor.
FIG. 2 is a block diagram showing the configuration of the embodiment. 1...CPU, 2...Program memory, 3...
...Discharge time constant memory, 4...KV setting device, 5...
...mAS setting device, 6, 7, 11...input port,
8... Output port, 9... SEC display, 10...
Digital switch.

Claims (1)

[Claims] 1. A first memory that approximates the discharge characteristics of a capacitor by an exponential function, measures the discharge time constant for the X-ray tube for each predetermined sample value of the KV value, and stores the measured discharge time constant; a second memory that stores a calculation program for calculating the shooting time based on the discharge time constant stored in the first memory and the set KV according to the calculation program stored in the second memory; value and
Perform calculations using the mAS value and calculate the KV value and m
a calculation device that calculates the shooting time corresponding to the AS value;
An imaging time pre-display device for a capacitor type X-ray apparatus, comprising a display device for displaying the imaging time.