p-channel metal-oxide-semiconductor (pMOS) dosimetric transistors are unique radiation dosimeters that have an extremely small size (the dimensions of the sensor element are less than 1 mm × 1 mm) and allow the measurement of dose in vivo in real time, which are especially important characteristics for radiotherapy. The isothermal, isochronal and UV annealing of pMOS dosimetric transistors have been investigated. The obtained results have shown that the high temperature annealing for thin and UV annealing for thick oxide, respectively, are very useful tools for radiation defect annealing. The spontaneous annealing is high, as a probable consequence of gate material (Al gate). The investigation has also shown that not only the threshold-voltage behaviour but also the behaviour of radiation defects in the oxide and at the oxide interface has to be known. The modelling of isothermal annealing at different temperatures has been performed.