Temperature effect on a phototransistor used as X-ray beam detector for diagnostic standard radiation qualities

This work presents some temperature effects on the signal-to-noise ratio of a bipolar phototransistor used as X-ray beam detector for diagnostic standard radiation qualities. The temperature of the phototransistor was varied to evaluate how its dark current can decrease and consequently obtain an improvement in the device response. The results show that in the lower temperature such an effect can reduce signal-to-noise ratio in almost 10 dB for the computed tomography radiation quality.