Kim Jung-In, Chun Minsoo, Wu Hong-Gyun, Chie Eui Kyu, Kim Hak Jae, Kim Jin Ho, Park Jong Min
Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea.
Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea.
Oncotarget. 2017 Jun 16;8(44):76076-76084. doi: 10.18632/oncotarget.18530. eCollection 2017 Sep 29.
To report a single-institution experience of gamma evaluations with 2%/1 mm for stereotactic ablative radiotherapy (SABR) delivered with volumetric modulated arc therapy (VMAT) technique, from January 2014 to January 2016. A total of 168 SABR VMAT plans were analyzed with a gamma criterion of 2%/1 mm, a threshold value of 10%, and a tolerance level of 90%. Of the 168 cases, four cases failed with 2%/1 mm. The average passing rate was 97.0% ± 2.5%. Three of the four failed cases showed passing rates higher than 90%, which was achieved by shifting the measuring device by 1 mm in the left-to-right or anterior-to-posterior directions. One failed case showed a passing rate higher than 90%, which was achieved by changing the threshold value from 10% to 5%, leading to an increase in the number of tested points from 26 to 51. Concerns regarding the high susceptibility of the gamma criterion of 2%/1 mm to setup errors of the measuring device are unnecessary based on our two-year experience, since only four cases failed with the 2%/1 mm from a total of 168 clinical cases. Therefore, the gamma criterion of 2%/1 mm could be successfully applied in the clinic with its high sensitivity to detect errors in VMAT plans.
报告2014年1月至2016年1月期间，采用容积调强弧形放疗（VMAT）技术进行立体定向消融放疗（SABR）时，使用2%/1 mm伽马评估的单机构经验。共分析了168个SABR VMAT计划，伽马标准为2%/1 mm，阈值为10%，耐受水平为90%。在168例病例中，有4例在2%/1 mm标准下失败。平均通过率为97.0%±2.5%。4例失败病例中有3例通过将测量设备在左右或前后方向移动1 mm，通过率高于90%。1例失败病例通过将阈值从10%更改为5%，使测试点数从26个增加到51个，通过率高于90%。根据我们两年的经验，基于2%/1 mm伽马标准对测量设备设置误差的高敏感性的担忧是不必要的，因为在总共168例临床病例中，只有4例在2%/1 mm标准下失败。因此，2%/1 mm伽马标准因其对检测VMAT计划中的误差具有高敏感性，可成功应用于临床。
