TCP/NTCP生物模型在胸中上段食管癌调强放疗中的应用

目的:探究TCP/NTCP生物模型在胸中上段食管癌放疗计划优化中的应用及剂量学特点。方法:回顾性分析47例胸中上段食管癌患者，为每位患者制定基于剂量体积（DV）限制的IMRT计划，在DV计划基础上添加对计划靶区（PTV）的TCP（限值90%、95%）生物模型以及危及器官的NTCP（限值10%、5%）模型优化，依次生成[PlanTCP90%]、[PlanTCP95%]、[PlanNTCP10%]、[PlanNTCP5%]4组计划。从剂量学及生物学参数方面评估计划间差异。结果:[PlanTCP90%]、[PlanTCP95%]相比于DV计划，靶区剂量参数均提高（P<0.05），其中[Dmean]、[D2%]、[D98%]分别提高（2.1%、9.8%）、（1.9%、9.8%）和（1.7%、9.3%），CI分别降低5%、20%，HI相近，TCP值分别提高2%、7%；危及器官受照剂量均有不同程度提高，[PlanTCP95%]增加更显著（P<0.05）。经TCP优化后的计划仅[PlanTCP90%]满足临床要求；[PlanNTCP5%]与DV计划相比，靶区、心脏相关剂量参数间差异没有统计学意义（P>0.05），但双肺[Dmean]、[V5 Gy]、[V10 Gy]、[V20 Gy]、NTCP值降低4.4%、1.6%、2.6%、6.2%、0.52%（P<0.05）。[PlanNTCP10%]与DV计划相比，PTV及危及器官相关剂量学参数间差异没有统计学意义（P>0.05）。结论:TCP/NTCP生物学优化可以使靶区及危及器官剂量更符合生物学要求，建议在胸中上段食管癌放疗DV计划优化后引入TCP/NTCP的评估，进而进行选择性的靶向深入优化。

Application of TCP/NTCP biological models in intensity-modulated radiotherapy for middle and upper esophageal carcinoma

Abstract: Objective To explore the application of tumor control probability/normal tissue complication probability (TCP/NTCP) biological models in the optimization of radiotherapy plans for middle and upper thoracic esophageal cancer, and to analyze the dosimetric characteristics. Methods A total of 47 patients with middle and upper thoracic esophageal cancer were selected retrospectively, and the intensity-modulated radiotherapy plan based on dose-volume (DV) limits was developed for each patient. Based on the DV plan, the TCP biological models (with limit values of 90% and 95%) for the planning target volume (PTV) and the NTCP biological models (with limit values of 10% and 5%) for the organs-at-risk (OAR) were added to generate 4 sets of plans, namely [PlanTCP90%], [PlanTCP95%], [PlanNTCP10%] and [PlanNTCP5%]. The differences in dosimetric and biological parameters between different plans were evaluated. Results Compared with those in DV plans, the dosimetric parameters of PTV in [PlanTCP90%] and [PlanTCP95%] were increased (P<0.05), in which the [Dmean]、[D2%] and [D98%] were increased by (2.1%, 9.8%), (1.9%, 9.8%) and (1.7% 9.3%), respectively, and the TCP was increased by 2% and 7%, respectively, but conformity index was decreased by 5% and 20%, and homogeneity index was similar in the 3 sets of plans. The radiation doses to OAR were increased in different degrees, and the increase in [PlanTCP95%] was more significant (P<0.05). After TCP optimization, only [PlanTCP90%] could meet the clinical requirements. The dosimetric parameters of PTV and heart in [PlanNTCP5%] and DV plan were basically the same（P>0.05）, but the [Dmean]、[V5 Gy]、[V10 Gy]、[V20 Gy] and NTCP for both lungs in [PlanNTCP5%] were decreased by 4.4%, 1.6%, 2.6%, 6.2% and 0.52% as compared with DV plan (P<0.05). The differences in the dose parameters of PTV and OAR between [PlanNTCP10%] [and ]DV plan were trivial (P>0.05). Conclusion TCP/NTCP biological optimization can make the dose to the target areas and OAR more in line with the biological requirements. It is suggested that the evaluation of TCP/NTCP should be introduced after the optimization of DV plan of radiotherapy for middle and upper thoracic esophageal cancer, and furthermore, the selective targeted in-depth optimization should be carried out.