Evaluation of precalibrated implantable MOSFET radiation dosimeters for megavoltage photon beams.

We have studied the response of factory calibrated implantable MOSFET detectors to absorbed doses from 100 to 400 cGy. The average measured dose is quite close to the true delivered dose, with the standard deviation falling between 1.4 and 3.6%. The measured dose tends to be slightly underestimated for smaller doses, while it tends to be slightly overestimated for larger doses. Thus, although the calibration of the detector is most accurate for doses close to the calibration dose of 200 cGy, it may be used over the range of commonly used doses in fractionated radiotherapy.