Investigation of Dosimetric Characteristics of a MOSFET Detector for Clinical Electron Beams

Objective: Studying of the fundamental dosimetric characteristics of metal oxide semiconductor field effect transistor (MOSFET) detectors to evaluate its use in clinical electron beam irradiations. Materials and Methods: In this study, GE-MS Saturne-43 linear accelerator was used . At first, Mosfet dedectors were calibrated for all electron energies. The fundamental dosimetric characteristics such as dose-linearity, reproducibility, angular dependence and field size dependence of MOSFET detectors were studied for 4,6,9,12,16 and 18 MeV electron energies. Results: Good linearity of the MOSFET dedector in the dose range of 10-500 cGy showed that it could be reliable detector for all electron applications. The energy dependence of a MOSFET dedector was within 3.0% for 6–18 MeV electron beams and 8% for 4 MeV ones. The results of the measurements performed using a spherical wax mini fantom demonstrate that the angular dependence of the MOSFET detector is small. MOSFET reproducibility is within 2%. Conclusion: This study shows that MOSFET detectors are suitable for dosimetry of electron beams in the energy range of 4–18 MeV. From the results observed it can be concluded that by applying proper calibration and correction factors, MOSFET may be used as in vivo detector for the dose verification for patients undergoing electron beam radiotherapy.