目的 利用3D打印共面坐标模板比较其辅助CT引导放射性粒子植入手术前、后肿瘤靶区、OAR物理剂量学评估参数的一致性.方法 利用计算机软件设计出3D打印共面坐标模板,建立坐标系,以中心点为中心设立x、y轴;定位时在患者体表确定固定针中心,并在患者体表勾画十字线,分别与共面坐标模板的中心点和x、y轴相对应.根据术前计划在3D打印共面坐标模板引导下行放射性粒子植入手术,术前、术中和术后计划,评估肿瘤靶区和正常组织接收剂量.评估参数包括D90、V100、V150、V200、MPD、CI、EI、HI.对术前、术后计划剂量学参数进行配对Wilcoxon检验.结果2016年8-10月入组14例患者.中位年龄61.5岁,KPS中位80分.14例患者14个病灶.植入部位分布为颈部4例、胸部3例、腹部5例、盆腔2例.8例患者植入部位曾接受放疗,6例患者植入部位未接受过放疗.所有患者均进行术中剂量优化.结果植入粒子活度中位0.625 mCi (0.55~0.75 mCi,1 Ci=3.7×1010 Bq),术前计划穿刺数中位9针(4~34针),植入粒子中位35颗(8~151颗);术后实际穿刺数中位9.5针(4~34针),植入粒子中位45.5颗(10~162颗).剂量学分析显示手术前、后病灶体积、D90、MPD、V100、V150、V200、CI、EI、HI均相近(P=0.135、0.208、0.104、0.542、0.754、0.583、0.426、0.326、0.952).结论 在3D打印共面坐标模板辅助引导下,通过术中剂量优化,放射性粒子植入术前、术后计划可获得良好的一致性.3D打印共面坐标模板应用方便、成本低廉,可考虑大规模推广应用.%Objective To compare the pre-and post-operative tumor target volume and to examine the consistency in physical dosimetric parameters of organs at risk (OAR) following 3D-printed coplanar template (3D-PCT)-assisted and CT-guided radioactive seed implantation.Methods The 3D-printed coplanar template was designed using a computer software, and the coordinate system was established where the center was used as the basis for setting the x axis and y axis.Crosses defining the center of treatment were drawn on the patient''s body and matched with the corresponding central point, x axis, and y axis of the coplanar template.3D-PCT-assisted and CT-guided radioactive seed implantation was performed based on the pre-operative plan, and the pre-operative, operative, and post-operative plans were designed to evaluate the target tumor volume and the normal dose received by the tissues.In addition, dosimetric parameters, including D90(minimum dose received by 90% of the gross target volume), V100, V150, V200(percentage of GTV that received 100%, 150%, and 200% of the prescribed dose, respectively), minimum peripheral dose (MPD), conformal index (CI), external index (EI), and homogeneity index (HI) in the pre-operative and post-operative plans were also assessed and compared using the Wilcoxon test. Results Fourteen patients treated in our institution from August to October, 2016 were included in this study. The median age of the patients was 61.5 years, and the median Karnofsky Performance Scale score was 80. A total of 14 lesions from the 14 patients were treated by seed implantation in the neck (n=4), chest (n=3), abdomen (n=5), and pelvis (n=2). Of the 14 patients that underwent implantation, 8 had previously received radiation therapy, and 6 had not received radiation therapy. Dosage optimization was performed for all patients during the operation. The median activity of the implanted seeds was 0.625 mCi (0.55-0.75 mCi,1 Ci=3.7×1010 Bq), and the preoperatively planned median number of needling and implanted seeds were 9(4-34) and 45.5(10-162), respectively. However, the actual median number of needling and implanted seeds were 9.5(4-34) and 45.5(10-162), respectively. Dosimetric analysis showed that there were no significant changes in tumor volume (P=0.135), D90(P=0.208), MPD (P=0.104), V100(P=0.542), V150(P=0.754), V200(P=0.583), CI (P=0.426), EI (P=0.326), and HI (P=0.952) after implantation. Conclusions 3D-PCT guidance and dosage optimization can result in good consistency between pre-and post-operative plans for radioactive seed implantation. 3D-PCT is a convenient and cheap technique suitable for large-scale clinical application.
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