Characterization of a floating-gate radiation sensor for X-ray dose detection

An ionizing radiation sensor based on a floating-gate capacitor with output in current mode has been tested as X-ray dose monitor for radiotherapy applications. The sensor had been initially designed for gamma rays dose detection in space missions proving its usefulness. In this new application the sensor has been tested with 6 MeV X rays at constant dose rate up to 3.6 krad of total dose. The measured sensitivity is -11.4 μA/krad. Once the output is corrected for ambient temperature variations the lowest detectable dose has been found to be 2 rad. Additionally, the sensor sensitivity to ambient temperature and supply voltage has been measured; we have found that both sensitivities are zero at specific total doses.