Quality Assurance Program of Electron Beams Using Thermoluminescence Dosimetry / 의학물리

ABSTRACT

The purpose of this study has been performed to investigate the possibility of external audit program using thermoluminescence dosimetry for electron beam in korea. The TLD system consists of LiF powder, type TLD-700 read with a PCL 3 reader. In order to determine a calibration coefficient of the TLD system, the reference dosimeters are irradiated to 2 Gy in a (60)Co beam at the KFDA The irradiation is performed under reference conditions is water phantom using the IAEA standard holder for TLD of electron beam. The energy correction factor is determined for LiF powder irradiated of dose to water 2 Gy in electron beams of 6, 9, 12, 16 and 20 MeV (Varian CL 2100C). The dose is determined according to the IAEA TRS-398 and by measurement with a PTW Roos type plane-parallel chamber. The TLD for each electron energy are positioned in water at reference depth. In this study, to verify of the accuracy of dose determination by the TLD system are performed through a 'blind' TLD irradiation. The results of blind test are 2.98%, 3.39% and 0.01% (1sigma) at 9, 16, 20 MeV, respectively. The value generally agrees within the acceptance level of 5% for electron beam. The results of this study prove the possibility of the TLD quality assurance program for electron beams. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.