Dose distribution of ¹⁹²Ir high-dose-rate brachytherapy of prostate cancer

The clinical procedure of Ir-192 high-dose-rate (HDR) brachytherapy for the treatment of prostate cancer is quite complicated. It is an important issue to choose a suitable dosimetry system for HDR brachytherapy. In this study, in-phantom measurements simulating the ¹⁹²Ir HDR brachytherapy for the treatment of prostate cancer were performed. In this study, in-phantom measurement simulating the Ir-192 HDR brachytherapy for the treatment of prostate cancer was performed. The innovative glass dosimeters (GDs) and thermoluminescence dosimeters (TLDs) were calibrated and used for in-phantom measurement. The discrepancy between measurements and doses calculated by treatment planning system (TPS) was analyzed. The signal uniformity of the batch RPLGD is within 2.05% (coefficient of variation). The reproducibility of each GD was 1.58%, and the dose corresponded to the delivered dose showed a good linear dependence. The reproducibility of readout value from each GD was 0.67%, and showed no fading effect within 35 days. The GD also showed energy independence with the photon energy greater than 200 keV. For in-phantom study, the compatibility (measured dose/calculated dose by TPS) was analyzed according to the location inside the phantom. For GDs and TLDs, the mean compatibility was 1.001 ± 0.03 (range, 0.97 to 1.04) and 1.01 ± 0.03 (range: 0.96 to 1.05), respectively, with single source dwell position. In multiple source dwell positions, the mean compatibility was 0.981 ± 0.03 (range: 0.93 to 1.02) for GDs. These results showed that the differences between the experimental and TPS calculated values were within ±5%. Results from the calibration of the dosimeters showed that GD was a suitable system for dosimetric measurement in radiation therapy.