The study of dose distribution of HDR brachytherapy for prostate cancer with glass dosimeter

Purpose: Many international investigations showed that external beam radiotherapy combined with high‐dose‐rate (HDR) brachytherapy will achieve therapeutic effect for prostate cancer. Hence, it is important to determine the treatment precision of in‐vivo dosimetry. However, a number of factors could potentially lead to the discrepancy between the predicted dose and the actually absorbed dose. In this study, in‐phantom measurements simulating the [formula omitted] HDR brachytherapy for the treatment of prostate cancer had been performed. Method and Materials: To validate our in‐vivo dosimetry system, a prostate phantom is designed. The innovative glass dosimeter (GD) and rod thermoluminescence dosimeter (TLD) were used in this study. The calibration of the dosimeter results showed the GD is a suitable dosimeter for radiation therapy dosimetry. Results: In this study, the compatibility factor (measured dose/calculated dose by TPS) was analyzed according to the locations in the phantom. For GDs and TLDs, the mean compatibility factor was 1.00±0.03 (range, 0.97 to 1.04) and 1.01±0.03 (range, 0.95 to 1.04) respectively with single source dwell position. In multiple source dwell positions, the mean compatibility factor was 0.98±0.03 (range, 0.93 to 1.02) for GDs. Conclusion: The results showed that the differences in dose between the measurement and calculation were within ±3% with single source dwell position. The measurements simulating the real clinical situations agree with the calculated values within 5%. In this study, results showed that GD displayed ideal properties for phantom‐dosimetry. Phantom‐dosimetry results show that dose delivery after CT‐based planning can be of clinically acceptable accuracy. © 2007, American Association of Physicists in Medicine. All rights reserved.