Development of Multi-Channel Dosimeter System for Measurement of Dose Distribution in Therapeutic Photon Beams

We investigated the characteristics of the multi-channel dosimeter (MCD) system for dose distribution by the moving wedge in clinical photon beams. Also we developed an electrometer for the multi-channel dosimeter system for radiation therapy. In dynamic field irradiation, the virtual wedge technique and its fraction methods are available through the computer-controlled asymmetric independent collimator. The modified MCD system consists of an electrometer, a solid detector and an array phantom. The MCD is used for the point dose measurement and the field size scanning. Thus, we evaluated the dosimetric characteristics of the virtual wedge and the conventional fixed wedge by the radiation field analyzer (RFA). In our analysis for the 6 and 10 MV photon beams, the maximum dose in the virtual-wedge and the fixed-wedge factors varied from 1.2 % to 1.6 % for square collimator setting ranging from 10 to 20 cm, respectively. We constructed the modified MCD system with the developed electrometer for radiation the...