TLD-based quality audit for radiotherapy dosimetry under reference and non-reference condition in Henan province

Objective: To verify the reliability of radiotherapy dosimetric parameters in reference and non-reference conditions using thermoluminescent dosimeters (TLDs). Methods: Using the established TLD method, the dose variations with different radiation field sizes and 45° wedge plate were verified for 10 photon beams of 6 MV, together with dosimetric parameters at the point of maximum axial dose for 4 electron beams of 9 MeV under reference and non-reference conditions. Comparisons were made between TLD results and finger ionization chamber results. Results: The average relative deviation, for 6 MV photon beams, between TLD results and finger ionization chamber measurements was 4.7%, within ±7% as required by the IAEA. The average relative deviation, for 9 MeV electron beam, between TLD results and plane parallel ionization chamber measurements was 2.4%, not beyond ±5% permitted by IAEA. Conclusions: Using TLD method to verify the radiotherapy dosimetric parameters in reference and non-reference conditions was reliable, simple and feasible. (authors)