| 摘要 |
The present invention relates to a radiation monitoring device which is utilized to measure the voltage supplied to an x-ray generator of an x-ray machine in terms of kVp units. The device includes a pair of detectors which are simultaneously exposed to an x-ray beam. The x-ray beam is filtered by a first amount before being supplied to the first detector, and is filtered by a second amount, greater than the first amount, before being supplied to the second detector. Both detectors generate an output signal having a magnitude proportional to the amount of radiation energy received. The ratio between the detector output signals is proportional to the amount of voltage supplied to the x-ray generator. The output signal of the first detector is an input to a first integrator which generates a voltage ramp output signal as an input to a trigger circuit. The output of the second detector is supplied to a second integrator which generates a second voltage ramp output signal as an input to a sample/hold circuit. When the magnitude of the ramp output signal of the first integrator reaches a predetermined reference level, the trigger circuit generates a signal to the sample/hold circuit which then stores the value of the output of the second integrator. The ratio between the stored value and the predetermined reference level corresponds to the ratio between the outputs the first and second detectors. The stored value is then biased to yield a voltage proportional by a multiple of ten to the actual kVp of the beam, such that a conventional voltmeter can be used to directly indicate the voltage in kVp units.
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