Evaluation Of Two-Dimensional Dosimeter Based On Thallium (I) Bromide For Measurement Of Surface Dose In Radiotherapy

In radiotherapy, side effects can occur on the skin because each patient's skin has a different level of sensitivity to radiation. Therefore, in clinical practice, point dose is measured to verify skin doses, although there is a problem, in that it is difficult to analyse the dose distribution for the body surface area. In this study, we constructed a film dosimeter based on polycrystalline thallium (I) bromide, evaluated its performance, and analysed the electrical properties according to the number of bending cycles to evaluate the mechanical flexibility. Further, an array dosimeter was constructed, and the dose distribution was analysed to evaluate the clinical effectiveness. As a result of the performance evaluation, reproducibility, linearity, and dose-rate dependence all satisfied the evaluation criteria. Percent depth dose showed similar results, and a difference of 0.027 when the slope of the depth in the range of 20-10 cm was compared with that of the thimble chamber. With regard to mechanical flexibility, as the number of bending cycles increased, the sensitivity tended to decrease. The clinical efficacy evaluation showed that the difference in dose distribution between the boundary field and non-field was approximately >= 40%, which decreased exponentially as the distance from the boundary field increased. The gap dose distribution showed an average difference of approximately >= 47% compared with the beam profile central axis. This suggests the possibility of application as a radiotherapy digital dosimeter, as well as the possibility of analysing the dose distribution on the body surface.