Department of radiation oncology, Cancer centre, West China Hospital, Sichuan University, Chengdu 610041, China.
Radiat Oncol. 2010 Feb 27;5:19. doi: 10.1186/1748-717X-5-19.
To study the set-up errors, PTV margin and toxicity of cone beam CT (CBCT) guided hypofractionated radiotherapy with active breathing control (ABC) for patients with non-small cell lung cancer (NSCLC) or metastatic tumors in lung.
32 tumors in 20 patients were treated. Based on the location of tumor, dose per fraction given to tumor was divided into three groups: 12 Gy, 8 Gy and 6 Gy. ABC is applied for every patient. During each treatment, patients receive CBCT scan for online set-up correction. The pre- and post-correction setup errors between fractions, the interfractional and intrafractional, set-up errors, PTV margin as well as toxicity are analyzed.
The pre-correction systematic and random errors in the left-right (LR), superior-inferior (SI), anterior-posterior (AP) directions were 3.7 mm and 5.3 mm, 3.1 mm and 2.1 mm, 3.7 mm and 2.8 mm, respectively, while the post-correction residual errors were 0.6 mm and 0.8 mm, 0.8 mm and 0.8 mm, 1.2 mm and 1.3 mm, respectively. There was an obvious intrafractional shift of tumor position. The pre-correction PTV margin was 9.5 mm in LR, 14.1 mm in SI and 8.2 mm in AP direction. After CBCT guided online correction, the PTV margin was markedly reduced in all three directions. The post-correction margins ranged 1.5 to 2.1 mm. The treatment was well tolerated by patients, of whom there were 4 (20%) grade1-2 acute pneumonitis, 3 (15%) grade1 acute esophagitis, 2 (10%) grade1 late pneumonitis and 1 (5%) grade 1 late esophagitis.
The positioning errors for lung SBRT using ABC were significant. Online correction with CBCT image guidance should be applied to reduce setup errors and PTV margin, which may reduce radiotherapy toxicity of tissues when ABC was used.
研究非小细胞肺癌（NSCLC）或肺部转移瘤患者应用主动呼吸控制（ABC）的锥形束 CT（CBCT）引导的亚分次放疗中的摆位误差、PTV 边界和毒性。
20 名患者的 32 个肿瘤接受治疗。根据肿瘤位置，给予肿瘤的分次剂量分为三组：12 Gy、8 Gy 和 6 Gy。为每位患者应用 ABC。每次治疗时，患者均接受 CBCT 扫描进行在线摆位校正。分析分次间、日内和日内的预校正和校正后摆位误差、PTV 边界以及毒性。
左右（LR）、上下（SI）、前后（AP）方向的预校正系统误差和随机误差分别为 3.7 mm 和 5.3 mm、3.1 mm 和 2.1 mm、3.7 mm 和 2.8 mm，而校正后残余误差分别为 0.6 mm 和 0.8 mm、0.8 mm 和 0.8 mm、1.2 mm 和 1.3 mm。肿瘤位置存在明显的日内移位。预校正时 LR、SI 和 AP 方向的 PTV 边界分别为 9.5 mm、14.1 mm 和 8.2 mm。应用 CBCT 引导在线校正后，所有三个方向的 PTV 边界均明显减少。校正后的边界范围为 1.5 至 2.1 mm。患者均能良好耐受治疗，其中 4 例（20%）出现 1-2 级急性肺炎，3 例（15%）出现 1 级急性食管炎，2 例（10%）出现 1 级迟发性肺炎，1 例（5%）出现 1 级迟发性食管炎。
应用 ABC 的肺部 SBRT 定位误差显著。应用 CBCT 图像引导的在线校正可减少摆位误差和 PTV 边界，当应用 ABC 时可能降低组织的放疗毒性。
