School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
Phys Med. 2019 Jan;57:72-79. doi: 10.1016/j.ejmp.2018.12.007. Epub 2018 Dec 26.
Rapid technological advances in high-dose-rate brachytherapy have led to a requirement for greater accuracy in treatment planning system calculations and in the verification of dose distributions. In high-dose-rate brachytherapy, it is important to measure the dose distribution in the low-dose region at a position away from the source in addition to the high-dose range in the proximity of the source. The aim of this study was to investigate the accuracy of a treatment plan designed for prostate cancer in the low-dose range using a normoxic N-vinylpyrrolidone-based polymer gel (VIPET gel) dosimeter containing inorganic salt as a sensitizer (iVIPET). The dose response was evaluated on the basis of the transverse relaxation rate (R) measured by magnetic resonance scanning. In the verification of the treatment plan, gamma analysis showed that the dose distributions obtained from the polymer gel dosimeter were in good agreement with those calculated by the treatment planning system. The gamma passing rate according to the 2%/2 mm criterion was 97.9%. The iVIPET gel dosimeter provided better accuracy for low doses than the normal VIPET gel dosimeter, demonstrating the potential to be a useful tool for quality assurance of the dose distribution delivered by high-dose-rate brachytherapy.
高剂量率近距离放射治疗中的快速技术进步，要求治疗计划系统的计算更加准确，并对剂量分布进行验证。在高剂量率近距离放射治疗中，除了在源附近的高剂量范围内，还需要测量远离源的位置的低剂量区域的剂量分布。本研究旨在研究使用含有无机盐作为敏化剂的正常氧 N-乙烯基吡咯烷酮基聚合物凝胶（VIPET 凝胶）剂量计（iVIPET）测量前列腺癌低剂量范围治疗计划的准确性。剂量响应是根据磁共振扫描测量的横向弛豫率（R）进行评估的。在治疗计划验证中，伽马分析表明，从聚合物凝胶剂量计获得的剂量分布与治疗计划系统计算的结果非常吻合。根据 2%/2mm 标准，伽马通过率为 97.9%。iVIPET 凝胶剂量计在低剂量下比正常 VIPET 凝胶剂量计具有更高的准确性，表明其有潜力成为高剂量率近距离放射治疗中剂量分布质量保证的有用工具。
