中文摘要：

目的 分析3D打印个体化非共面模板（简称3D打印模板）联合CT引导放射性125I粒子植入治疗局部复发直肠癌患者术前和术后主要剂量学参数的差异。方法 回顾性分析2016年2至4月北京大学第三医院接受3D打印模板联合CT引导放射性125I粒子治疗的10例局部复发直肠癌患者。治疗流程：术前CT模拟定位、术前计划设计、3D打印个体化模板设计制作、3D打印模板辅助CT引导粒子植入和术后即刻CT扫描剂量验证。本组患者中位粒子活度0.63（0.58～0.70） mCi [（2.15～2.59）×107 Bq]，中位粒子数目80（19～192）颗。评估术前计划、术后验证90%靶区体积的剂量（D90）、100%靶区体积的剂量（D100）、100%处方剂量的靶区体积（V100）、150%处方剂量的靶区体积（V150）、适形指数（CI）、靶区外体积指数（EI）和均匀性指数（HI）等剂量学参数，以及膀胱、肠道等危及器官受照射剂量。配对t检验评价患者3D打印模板联合CT引导放射性粒子植入术前计划、术后验证的吻合度。结果 10例患者术前计划、术后验证的中位D90分别是13 761.0和12 798.8 cGy，中位D100分别是5 293.6和5 397.9 cGy，中位V100分别是90.0%和90.0%，中位V150分别是63.8%和62.4%，中位CI分别是0.73和0.67，中位EI分别是0.22和0.30，中位HI分别是0.29和0.31。术前计划、术后验证的膀胱D2cc的中位数分别是3 088.8和4 240.4 cGy，肠道D2cc的中位数分别是7 051.6和7 903.9 cGy。术前计划、术后验证的主要剂量学参数和危及器官剂量吻合度好，差异均无统计学意义。结论 3D打印模板辅助CT引导放射性125I粒子植入治疗盆腔复发直肠癌，有利于实现术前计划的设计，达到预计的肿瘤处方剂量和危及器官的剂量限值，有助于实现精准放射性粒子植入和质量控制的标准化。

英文摘要：

Objective To analyze the difference of dosimetric parameters between pre-plan and post-plan of 125I radioactive seed implantation assisted by 3D printing individual non-coplanar template （3D printing template） for locally recurrent rectal cancer （LRRC）.Methods From February 2016 to April 2016, a total of 10 patients with locally recurrent rectal cancer received 125I seeds implantation under CT guidance assisted by 3D printing template in Department of Radiation Oncology, Peking University Third Hospital.Each patient underwent CT simulation, three-dimentional treatment planning pre-implantation, 3D printing template design, radioactive seed implantation assisted by 3D printing template and dosimetric verification post implantation. The median activity of seed was 0.63 mCi （0.58 to 0.7 mCi） （2.15- 2.59×107 Bq）, and the median number of seeds was 80 （19 to 192）. D90, D100, V100, V150, CI, EI, HI, D5cc, D2cc of bladder and bowel of pre-plan and post-plan were calculated, respectively.Paired t test was used to evaluate the difference of dosimetric parameters between pre-plan and post-plan.Results The median D90 of pre-plan and post-plan were 13 761.0 and 12 798.8 cGy, respectively.The median D100 of pre-plan and post-plan were 5 293.6 and 5 397.9 cGy, respectively.The median V100 of pre-plan and post-plan were 90.0% and 90.0%, respectively.The median V150 of pre-plan and post-plan were 63.8% and 62.4%, respectively.The median CI of pre-plan and post-plan were 0.73 and 0.67.The median EI of pre-plan and post-plan were 0.22 and 0.30, respectively. The median HI of pre-plan and post-plan were 0.29 and 0.31.The median bladder D2cc of pre-plan and post-plan were 3 088.8 and 4 240.4 cGy, respectively.The median bowel D2cc of pre-plan and post-plan were 7 051.6 and 7 903.9 cGy, respectively.Conclusions 3D printing template might be helpful for locally recurrent rectal cancer patients who received 125I radioactive seed implantation assisted by 3D printing individual template.Seed implantation might have m