肺癌适形放疗中两个阶段治疗计划叠加的可行性分析

Analysis of the practicability to combine two-course treatment plan in lung cancer patient

目的:研究同一患者分前后2个阶段并在不同体位条件下完成总周期的治疗中,将2个阶段治疗计划相叠加后评价总周期靶区和危及器官剂量的可行性和临床应用。方法:回顾性分析小细胞肺癌患者10例,每例患者在总周期中采用不同体位重新定位1次,分2个阶段完成治疗,每个阶段分别制定三维适形计划,周期总剂量为50Gy。均采用Cadplan R 3.1.2三维治疗计划系统完成治疗计划的设计。通过治疗计划系统叠加每例患者总周期中2个阶段的治疗计划,分析将2个阶段治疗计划叠加的可行性以及第1阶段与第2阶段治疗计划相叠加后临床应用的可行性分析。结果:前后2个阶段气管隆突在左右、前后以及头尾方向运动密切正相关(相关性检验,P值均<0.05),证明以气管隆突作为2个阶段的治疗计划叠加标识的可行性;前后2个阶段靶区和危及器官体积变化显示除PTV2的体积变异大差异有统计学意义外,其余差异均无统计学意义,并且各危及器官剂量学相关性分析中仅脊髓最大剂量在复制计划和原计划之间无相关性外(r=0.34,P=0.34),其余剂量参数均显示出密切正相关。结论:运用三维治疗计划系统将同一患者2个阶段不同体位的治疗计划叠加时,在保证与叠加计划等中心点坐标密切相关的解剖结构在2个阶段空间位置一致,以及2个阶段的靶区和危及器官体积无明显差异的前提下,可以对体位不同的2个阶段的治疗计划进行叠加,并在临床上运用叠加计划总体评价总体周期中的靶区和危及器官剂量。

OBJECTIVE： To analyze the feasibility and the practicability of combining two-course treatment plans of one patient who was localized in different positions during two-course.METHODS： Ten patients with small cell lung cancer were chosen.According to the clinical requirement,all patients were localized twice with different positions in total course.Using the Cadplan R 3.1.2 treatment planning system,conformal planning were designed for each patient in two-course.The total radiation dose was 50 Gy.The reproductive plans were applied to evaluate the dosimetric distribution to target volume and the surrounding organs at risk in the total course.RESULTS： The movements of carina in three-dimensional directions were closely correlated between two courses（P0.05）.No significant disparities in target volumes and normal tissue volumes were found except for the volume of PTV2.Except for maximum dose of spinal cord（r=0.34,P=0.34）,positive correlations of dosimetric parameters were displayed between reproductive plans and original plans.CONCLUSIONS： To assure the accuracy of isocenter＇s coordinate in combined treatment plans and the positive correlations of dosimetric parameters between reproductive plans and original plans,it is feasible and the practicable to combine two-course treatment plans of one patient who is localized in different position during two-course.