JPH0143277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that generates radiation, and in particular, a safety mechanism that determines whether the generated radiation is output according to a preset intensity and determines whether or not the device can continue operating. It is prepared.

FIG. 1 shows the configuration of a linear electron accelerator as an example of a radiation generating device. In Figure 1, 1 is an electron gun that generates an electron beam, 2 is an acceleration tube that accelerates the electron beam, and 3 is a deflection system that deflects the accelerated electron beam. There may be no. 4 is a radiation generating mechanism that generates radiation by an electron beam; 5 is the generated radiation. 6 is a detector for monitoring the output of radiation, 7 is an amplifier for electrical signals proportional to the detected radiation intensity, 8 is a display unit for radiation output intensity, and 9 is for measuring the generated radiation dose. The integration circuit 10 is a display section for the integrated radiation dose. 11
1 is an output setting mechanism for setting the output intensity of radiation, 12 is an output stabilization circuit, 13 is a pulse trigger generator, 14 is a high voltage pulse modulator, 15a, 1
5b is a pulse transformer, and 16 is a high power microwave generator.

Further, FIG. 2 shows an example of a mechanism for stopping generated radiation. 17 is an integrated radiation setting mechanism that sets the integrated amount of radiation to be irradiated; 18 is a comparator that determines whether the output value of the integrating circuit 9 has reached the value specified by the integrated radiation setting mechanism 17; In the example shown in the figure, when the output value of the integrating circuit 9 is less than the value specified by the integrated radiation setting mechanism 17, the comparator 18 outputs logic circuit "1", and the output value of the integrating circuit 9 is less than the value specified by the integrated radiation setting mechanism 17. When the value exceeds the value, "0" is output. 19 is a time mechanism that sets the maximum duration of radiation generation; 20 is a timer mechanism that measures time simultaneously with radiation generation; and 21 is a display unit for displaying the time of radiation generation. 22 is a comparator similar to 18, but when the output of the timer mechanism 20 is less than the value specified by the time setting mechanism 19, it outputs "1", and when the output value of 20 exceeds the specified value of 19. Outputs “0”. 23 is a switch mechanism that turns on/off radiation generation. Switch mechanism 2 that outputs “1” when radiation generation is turned on.
3 instructs the device to generate radiation, the timer mechanism 20 starts measuring time. 24 is a sequence section for radiation generation, which is shown here as an AND circuit. That is, when the outputs of comparators 18 and 22 are both "1", when radiation generation is turned on by the switch mechanism, the output of comparator 24 becomes "1",
At the same time that the output of the comparator becomes "0", the 24 output becomes "0". 25 is a control unit that controls ON/OFF of radiation generation of the radiation generating device. 26 does not show the relationship with other parts, but before radiation generation, the display part 1
Reset the display of 0, 21 to the initial value, and 9,
If a value is held in the circuit 21 due to the previous radiation generation, this is also a reset mechanism that resets it to the initial value.

Next, the operation will be explained. Although the example in FIG. 1 shows a linear electron accelerator, a pulse trigger generator 13 generates a pulse based on the output of the output stabilizing circuit 12. The output stabilizing circuit 12 stabilizes the radiation output, and in this case, stabilization can be achieved by controlling the pulse repetition frequency. This pulse trigger operates the high voltage pulse modulator 14, and when a high voltage pulse is generated, it is boosted to a predetermined voltage by each of the pulse transformers 15a and 15b and applied to the electron gun 1 and the microwave generator 16. At the same time as the electron beam is generated, high-power microwaves are generated.
In the acceleration tube 2, the electron beam is accelerated by microwaves, and if a deflection system is provided, the accelerated electron beam is deflected by the deflection system 3 and enters the radiation generating mechanism 4. Radiation 5 is generated from here. When this radiation 5 is detected by the detector 6, the detection signal is amplified by the amplifier 7, the output intensity of the radiation is displayed on the display section 8, and the output stabilization circuit 12
, and forms a feedback circuit that is stabilized at the output set by the output setting mechanism 11. On the other hand, the output of the amplifier 7 is input to an integration circuit, which calculates the integrated value of the generated radiation and displays this value on the display unit 10.

FIG. 2 shows an example of the function of stopping the radiation generation of the radiation generating device. Radiation generators are usually equipped with either or both of a mechanism for setting the cumulative radiation dose and a mechanism for setting the duration of radiation generation, or a similar function. Figure 2 explains the interlock mechanism that stops the generation of radiation when the radiation dose set by the cumulative radiation dose setting mechanism is reached, or when the radiation generation time is reached. . The comparator 18 functions as a logic circuit that generates a "0" output when the output value of the integration circuit 9 reaches the value set by the integrated radiation setting mechanism 17 or more, and operates as a first interlock circuit that stops the generation of radiation. It constitutes a mechanism. Similarly, comparator 2
2, when the value of the radiation generation time by the timer mechanism 20 reaches the value set by the radiation generation time setting mechanism 19, the second circuit becomes a logic circuit that generates a "0" output and stops the generation of radiation. It constitutes an interlock mechanism. The display unit 21 displays the time measured by the timer mechanism 20. When the reset mechanism 26 resets the integrating circuit 9, timer mechanism 20, and display sections 10, 21 to their initial values before turning on the radiation generation switch, the outputs of the comparators 18, 22 become "1" and the sequence section consisting of an AND circuit. 24, if the switch mechanism 23 is turned on, radiation can be generated.

In the manner described above, radiation can be generated by the switch mechanism 23.

Next, to stop the radiation, switch mechanism 23 is activated.
This can be achieved by turning off the comparator 18 or 22 and outputting "0" from either of the comparators 18 and 22. That is, radiation is stopped depending on whether the integrated value of the generated radiation reaches the planned integrated radiation dose or the time during which the radiation is being generated reaches the planned radiation generation duration time.

In this type of apparatus, even if there is an abnormality in the equipment, the operation of the apparatus will not be stopped until the scheduled time has elapsed, and it takes time until the abnormality is recognized.
For this reason, particularly in radiation generating apparatuses used as treatment machines, there has been a drawback that there is a possibility that patients may be exposed to unnecessary radiation that does not comply with the treatment plan.

This invention was made in order to eliminate the drawbacks of the above-mentioned devices, and uses a mechanism to set the radiation output of the device, so that the radiation output intensity obtained by operating the device is adjusted according to the planned radiation output. To provide a device having a mechanism that instantly stops the generation of radiation when the amount changes beyond an allowable amount, thereby preventing generation of unnecessary radiation that does not follow the planned radiation output. The purpose is to

An embodiment of this invention will be described below. FIG. 3 is a diagram showing an interlock mechanism used in the present invention, and FIG. 4 is a diagram showing an embodiment of the present invention in which the function of FIG. 2 is added to the device of FIG. 3. In FIGS. 3 and 4, 30 is an upper limit setting calculation section, 31 is a lower limit setting calculation section, 32 is a comparator, and 33 is also a comparator. 34, 35 are
It is an AND circuit.

The upper limit setting calculation unit 30 sets the upper limit of the output fluctuation allowed for the radiation output value determined by the radiation output setting mechanism 11, and the lower limit setting calculation unit 31 similarly sets the permissible lower limit of the output fluctuation. Set. The comparator 32 determines whether or not the radiation output exceeds the permissible upper limit set by the upper limit setting calculation section 30, and the comparator 33 similarly determines the permissible lower limit.

The operation will be explained below. In FIGS. 3 and 4, the output intensity of the radiation 5 is stabilized at a value determined by the output setting mechanism 11, and the system is operated. However, if for some reason the radiation output becomes too high or too low, the device according to the present invention can immediately stop the generation of radiation.
That is, in the upper limit setting calculation section 30, the output setting mechanism 11
For the radiation output X _S determined by , the allowable output fluctuation value △X _V is calculated, and X _S + △X _V is calculated.
For example, if a fixed bias is added to the output of the output setting mechanism 11, △X _V becomes a constant, and no matter what value of X _S , the constant △X _V becomes the allowable output error. Alternatively, if the upper limit setting calculation unit 30 is a calculation amplifier with an amplification degree of (1+k) times, △X _V changes according to the X _S value, and X _S + △X _V = (1 + k) X _S The allowable output error is the set output multiplied by a certain percentage. Therefore, the upper limit setting calculation unit 30 can be set to calculate a value that determines the upper limit of allowable fluctuation of the output radiation intensity with respect to the set output. The lower limit setting calculation unit 31 is similar, and can be set to calculate a value X _S −ΔX _D that determines the lower limit of the permissible variation of the output radiation intensity with respect to the set output.

In FIG. 5, the upper limit setting calculation section 30 is composed of an arithmetic amplifier with an amplification degree of (1+k) times, and the lower limit setting arithmetic section 31 is composed of an arithmetic amplifier with an amplification degree of (1-k) times. This is a diagram showing the relationship between the radiation output and the set value X _S when the upper limit X _S (1+k) and the lower limit X _S
The radiation output is limited within the permissible range determined by (1-k).

Next, regarding the relationship with the output radiation, the output of the amplifier 7 is proportional to the output radiation intensity, so let this be X _O , and if the radiation generator is normally operated, then X _O = X _S. It has been stabilized. In other words, in such a case, the relationship is X _S −△X _D <X _O <X _S <△X _V. It is preferable that the comparator 32 obtains a logic circuit output of "1" when X _O <X _S +ΔX _V.
That is, when X _O >X _S +ΔX _V , the output of the comparator 32 becomes the logic circuit output "0". Similarly, in comparator 33
When X _S −△X _D <X _O , the output is logic circuit output “1”
Therefore, when X _S −△X _D > X _O , the logic circuit output is set to “0”. In the AND circuit 34, when both outputs of the comparators 32 and 33 are "1", the output becomes "1". When the output of the AND circuit 34 is "1", the control unit 25 that controls ON/OFF of radiation generation can turn on the radiation generation, and when the output of the AND circuit 34 is "0", the radiation generation can be turned OFF. That is, the output of both comparators 32 and 33 is "0".
When this occurs, radiation generation is stopped, forming a third interlock mechanism.

Note that the mechanism for stopping the generation of radiation when the cumulative amount of radiation exceeds a set value and when the duration of radiation exceeds a set value has been explained with reference to FIG. 2, and will therefore be omitted here.

Therefore, especially when using a radiation generating device for treatment, even if the radiation output becomes excessive or insufficient for some reason, and even when the radiation reaches a certain time or a predetermined cumulative dose, Since the generation can be stopped immediately, there is no need for unnecessary irradiation.

It can be applied to any radiation generating device, and does not need to have the output stabilizing circuit 12. Also, since the above explanation is directed to a linear accelerator, the pulse generator 13 is shown in FIG. Although shown, it can be used in any radiation generating device as a mechanism for determining the radiation output.

As described above, according to the present invention, when the radiation output becomes too high or too low, it is possible to immediately stop the radiation, and when the radiation output becomes too high or low compared to the allowable level, it is possible to stop the radiation as expected in the irradiation plan. It is possible to prevent the generation of unnecessary radiation. Furthermore, even when the radiation generation time exceeds a predetermined time or the cumulative amount of radiation exceeds a predetermined amount, radiation is immediately stopped, thereby preventing a mass exposure accident. In particular, for treatment equipment, improving the accuracy of treatment for patients,
This is an essential mechanism for performing treatment according to the treatment plan.

[Brief explanation of drawings]

Figure 1 is a block diagram of the linear electron accelerator, Figure 2
The figure is a block diagram showing an example of the generated radiation stopping mechanism.
Fig. 3 is a block diagram of a generated radiation stopping mechanism used in this invention, Fig. 4 is a block diagram of an embodiment according to this invention, and Fig. 5 is an example of the upper and lower limits of the output of the radiation generating device according to this invention. FIG. In the figure, 6...detector, 7...amplifier, 1
1... Output setting mechanism, 12... Output stabilization circuit,
25... Radiation generation ON/OFF control unit, 30...
Upper limit setting calculation section, 31...Lower limit setting calculation section, 32
. . . comparator, 33 . . . comparator, 34 . . . AND circuit. Note that the same reference numerals in the figures represent the same parts.

Claims (1)

[Claims] 1. A mechanism that generates radiation, a detector that detects the radiation generated by this mechanism, an output setting mechanism that variably sets the output intensity of radiation, and an integration circuit that measures the radiation dose detected by the detector. , an integrated radiation setting mechanism that sets the integrated amount of radiation to be irradiated, and a first interlock mechanism that stops the generation of the radiation when the output value of the integrating circuit exceeds the value set by the integrated radiation setting mechanism. a timer mechanism that simultaneously measures the generation time of the radiation, a time setting mechanism that sets the maximum duration of radiation generation, and an output of the timer mechanism that measures the value set by the time setting mechanism. The upper limit of the output fluctuation value △X _V that is allowed according to the radiation output value X _S determined by the second interlock mechanism that stops the generation of radiation when exceeding the above output setting mechanism (X _S + _△ ), and a lower limit setting that sets the lower limit of the allowable output fluctuation value △X _D according to the radiation output value X _S determined by the output setting mechanism (X _S − _△ a third interface that stops the generation of the radiation when the output intensity of the radiation detected by the detector exceeds the upper limit (X _S + △X _V ) or the lower limit (X _S + △X _D ); A radiation generating device equipped with a lock mechanism.