In-Phantom Peripheral Organ Doses from Prostate Irradiation Using 18 MV External Beam Radiotherapy Measured with 6LiF:Mg,Cu,P & 7LiF:Mg,Cu,P Glass-Rod TLDs

A radiation dosimetry technique based on pairs of 6 LiF:Mg,Cu,P and 7 LiF:Mg,Cu,P glass-rod TLDs was developed for measuring peripheral photon and neutron doses in the humanoid Rando phantom as a result of prostate irra- diation using the 18 MV three-dimensional conformal radio- therapy (3D-CRT). The peripheral doses for different organs were estimated from TLD measurements and the risks of radiation-induced second malignancy were estimated using the competitive risk and linear no-threshold models. It was observed that following 80 Gy prostate irradiation using 18 MV 3D-CRT technique, both photons and neutrons doses ranged from approximately 97 mSv (in thyroid) to 807 mSv (in colon). Using the competitive risk model, the estimated risk of second malignancy was found to be ranging from 0.5% (for lungs) to 3.3% (for colon). Due to low doses ( 10 MV) linac. The measured peripheral doses can be used to evaluate the risk of second malignancy in the irradiated distant organs. In this study, a radiation dosimetry technique based on novel 6 LiF;Mg,Cu,P and 7 LiF:Mg,Cu,P glass-rod thermoluminescence dosimeters (TLDs) has been developed to carry out measurements of peripheral photon and neutron doses simultaneously in the Rando phantom irradiated to 80 Gy dose using 4-field 3D- CRT delivered by the 18 MV Varian iX linac.