Exposure preset apparatus for a particle accelerator

The present invention relates to the output measurement of a particle accelerator and a preset apparatus for accurately presetting the exposure during short-term irradiation. In the conventional apparatus there were cases when the preset value of the dosage was not correctly applied to the target. Furthermore, timers added to improve the operation were in effective for irradiation intervals of the order of 0.5 seconds. The present invention is designed to allow presetting at the pulse number of the smallest unit of exposure and to minimize exposure errors during short-term irradiation. The preset apparatus is characterized by an irradiation monitor capable of pulse action, an integrating circuit which integrates the output of the monitor, an exposure dose rate indicating device, a counter which counts the pulse number of the monitor's pulse output, and a device capable of halting irradiation when the counter's value reaches a given value. Thus this invention provides a preset apparatus for linear electron accelerators used in nondestructive tests of medical treatment, whereby exposure during short-term irradiation can be accurately controlled. (Hiroshige, T.)