Circuit arrangement for radiation dose-measurement

Claim 1

X-RAY MEASURING APPARATUS FOR MEASURING THE ENERGY SUPPLIED TO A SPECIMEN IRRADIATED BY A SOURCE OF X-RAYS, COMPRISING AN IONIZATION CHAMBER FOR PRODUCING AN ELECTRICAL CURRENT PROPORTIONAL THERETO DURING A FIRST TIME PERIOD, AN INTEGRATING CAPACITOR COUPLED TO SAID IONIZATION CHAMBER FOR STORING AN ELECTRICAL CHARGE OF A GIVEN POLARITY DURING SAID FIRST TIME PERIOD, TIMING MEANS FOR PRODUCING AN INDICATION OF THE AMOUNT OF RADIATION SUPPLIED BY SAID X-RAY SOURCE, A TRIGGER CIRCUIT, CONTROL MEANS FOR ACTUATING SAID TIMING MEANS TO BEGIN A TIMING OPERATION AT THE END OF SAID FIRST TIME PERIOD, SAID CONTROL MEANS COMPRISING MEANS FOR PRODUCING A VARYING VOLTAGE OF OPPOSITE POLARITY TO SAID GIVEN POLARITY AND MEANS FOR COMBINING SAID VARYING VOLTAGE AND SAID STORED CHARGE AND SUPPLYING SAME AS A CONTROL INPUT TO SAID TRIGGER CIRCUIT, SAID TRIGGER CIRCUIT BEING RESPONSIVE TO THE COMBINED VOLTAGES AT ITS CONTROL INPUT FOR SUPPLYING A CONTROL SIGNAL TO SAID TIMING MEANS THEREBY TO TERMINATE SAID TIMING OPERATION AFTER A PERIOD OF TIME DETERMINED BY THE CHARGE STORED ON SAID CAPACITOR.