Correction of MOSFET dosimeter reading for low-energy scattered photons in a physical phantom

Abstract

The MOSFET dosimeter is mainly made of silicon and epoxy and shows some energy dependence for low energy photons; it overestimates absorbed dose for low energy scattered photons when it is used in a physical phantom. This study determines the relative response of the MOSFET dosimeter to the true absorbed dose (to tissue) in a physical phantom by Monte Carlo simulations. The relative responses of the MOSFET dosimeter were calculated as 1.0-1.2 and 1.0-1.1 for 137Cs and 60Co, respectively, considering all the dosimeter locations (in the phantom) and directions and six orthogonal photon beam directions. This result shows that if we do not use appropriate correction factors, the measurement of an organ dose with a MOSFET dosimeter could result in up to 20% of overestimation depending on the detailed measurement conditions.