Application of pMOS dosimeters in low-field mode for radiation dose measurements which could be used in radiotherapy

Abstract

The pMOS dosimeters sensitivity (Tyndall National Institute, Cork, Ireland) to gamma and X-ray irradiation and 2000 h fading at room temperature is presented. The radiation fields were created using a 60Co source for two dose ranges (1-5 Gy and 10-50 Gy) as well as for X-ray units of a 280 kV spectrum for a single dose range from 0.1 to 1 Gy. Irradiation was performed in low-field mode (no gate bias during irradiation, Virr = 0 V), sensitivity characterized by the threshold voltage shift as a function of the absorbed radiation dose and time after irradiation. Linear dependence between the threshold voltage shift and the absorbed radiation dose was only established for pMOS dosimeters which were irradiated by gamma rays in the dose range of 1 to 5 Gy. Obtained results show that the sensitivity of these components is much higher in case of X-ray radiation than in that of gamma ray radiation. Moreover, the fading of irradiated pMOS dosimeters with X-rays is higher than in the ones irradiated with gamma rays. [Projekat Ministarstva nauke Republike Srbije, br. 171007]

Keywords

• pMOS dosimeter
• radiation dose
• threshold voltage shift
• fading
• in vivo dosimetry