Tachibana Hidenobu, Watanabe Yusuke, Kurokawa Shogo, Maeyama Takuya, Hiroki Tomoyuki, Ikoma Hideaki, Hirashima Hideaki, Kojima Hironori, Shiinoki Takehiro, Tanimoto Yuuki, Shimizu Hidetoshi, Shishido Hiroki, Oka Yoshitaka, Hirose Taka-Aki, Kinjo Masashi, Morozumi Takuya, Kurooka Masahiko, Suzuki Hidekazu, Saito Tomohiko, Fujita Keiichi, Shirata Ryosuke, Inada Ryuji, Yada Ryuichi, Yamashita Mikiko, Kondo Kazuto, Hanada Takashi, Takenaka Tadashi, Usui Keisuke, Okamoto Hiroyuki, Asakura Hiroshi, Notake Ryoichi, Kojima Toru, Kumazaki Yu, Hatanaka Shogo, Kikumura Riki, Nakajima Masaru, Nakada Ryosei, Suzuki Ryusuke, Mizuno Hideyuki, Kawamura Shinji, Nakamura Mistuhiro, Akimoto Tetsuo
Radiation Safety and Quality Assurance division, National Cancer Center Hospital East, Kashiwa, Chiba, Japan.
School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
Brachytherapy. 2022 Nov-Dec;21(6):956-967. doi: 10.1016/j.brachy.2022.06.006. Epub 2022 Jul 25.
To quantify dose delivery errors for high-dose-rate image-guided brachytherapy (HDR-IGBT) using an independent end-to-end dose delivery quality assurance test at multiple institutions. The novelty of our study is that this is the first multi-institutional end-to-end dose delivery study in the world.
The postal audit used a polymer gel dosimeter in a cylindrical acrylic container for the afterloading system. Image acquisition using computed tomography, treatment planning, and irradiation were performed at each institution. Dose distribution comparison between the plan and gel measurement was performed. The percentage of pixels satisfying the absolute-dose gamma criterion was reviewed.
Thirty-five institutions participated in this study. The dose uncertainty was 3.6% ± 2.3% (mean ± 1.96σ). The geometric uncertainty with a coverage factor of k = 2 was 3.5 mm. The tolerance level was set to the gamma passing rate of 95% with the agreement criterion of 5% (global)/3 mm, which was determined from the uncertainty estimation. The percentage of pixels satisfying the gamma criterion was 90.4% ± 32.2% (mean ± 1.96σ). Sixty-six percent (23/35) of the institutions passed the verification. Of the institutions that failed the verification, 75% (9/12) had incorrect inputs of the offset between the catheter tip and indexer length in treatment planning and 17% (2/12) had incorrect catheter reconstruction in treatment planning.
The methodology should be useful for comprehensively checking the accuracy of HDR-IGBT dose delivery and credentialing clinical studies. The results of our study highlight the high risk of large source positional errors while delivering dose for HDR-IGBT in clinical practices.
通过在多个机构进行独立的端到端剂量输送质量保证测试，对高剂量率图像引导近距离放射治疗（HDR-IGBT）的剂量输送误差进行量化。我们研究的新颖之处在于，这是世界上首个多机构端到端剂量输送研究。
邮政审计在用于后装系统的圆柱形丙烯酸容器中使用了聚合物凝胶剂量计。每个机构都进行了计算机断层扫描图像采集、治疗计划制定和照射。对计划剂量分布与凝胶测量结果进行了比较。审查了满足绝对剂量伽马标准的像素百分比。
35个机构参与了本研究。剂量不确定度为3.6%±2.3%（均值±1.96σ）。覆盖因子k = 2时的几何不确定度为3.5毫米。根据不确定度估计，将容差水平设定为伽马通过率95%，一致性标准为5%（全局）/3毫米。满足伽马标准的像素百分比为90.4%±32.2%（均值±1.96σ）。66%（23/35）的机构通过了验证。在未通过验证的机构中，75%（9/12）在治疗计划中导管尖端与分度器长度之间的偏移输入错误，17%（2/12）在治疗计划中导管重建错误。
该方法对于全面检查HDR-IGBT剂量输送的准确性和对临床研究进行资格认证应是有用的。我们的研究结果突出了在临床实践中进行HDR-IGBT剂量输送时源位置出现大误差的高风险。
