Feasibility study of glass dosimeter postal dosimetry audit of high-energy radiotherapy photon beams

AuthorIntroductionThe characteristics of a glass dosimeter were investigated for its potential use as a tool for postal dose audits. Reproducibility, energy dependence, field size and depth dependence were compared to those of a thermoluminescence dosimeter (TLD), which has been the major tool for postal dose audits worldwide.Materials and methodsA glass dosimeter, GD-302M (Asahi Techno Glass Co.) and a TLD, TLD-100 chip (Harshaw Co.) were irradiated with γ-rays from a 60Co unit and X-rays from a medical linear accelerator (4, 6, 10 and 20 MV).ResultsThe dosimetric characteristics of the glass dosimeter were almost equivalent to those of the TLD, in terms of utility for dosimetry under the reference condition, which is a 10 × 10 cm2 field and 10 cm depth. Because of its reduced fading, compared to the TLD, and easy quality control with the ID number, the glass dosimeter proved to be a suitable tool for postal dose audits. Then, we conducted postal dose surveys of over 100 facilities and got good agreement, with a standard deviation of about 1.3%.ConclusionsBased on this study, postal dose audits throughout Japan will be carried out using a glass dosimeter.