边界距离散射剂量计划模式对肺癌脑转移瘤射波刀治疗的剂量学影响研究

Dosimetric effects of boundary range scattering dose planning mode on Cyberknife treatment of lung cancer brain metastases

目的:探讨边界距离散射剂量(boundary range scattering dose,BRSD)计划模式对肺癌脑转移瘤射波刀治疗的剂量学影响。方法:选取2021年1月1日至2021年12月31日在某院放射治疗科治疗的15例肺癌脑转移瘤患者的定位影像资料,将其导入射波刀的Multiplan 4.0.3治疗计划系统,针对每名患者分别制订分次立体定向放疗(fractio-nated stereotactic radiotherapy,FSRT)计划(作为FSRT计划组)和BRSD计划(作为BRSD计划组)。其中FSRT计划组按常规方法针对计划靶区(planning target volume,PTV)制订计划,使V_(100)覆盖95%以上的PTV;BRSD计划组针对大体肿瘤靶区(gross tumor volume,GTV)制订计划,参数条件与FSRT计划组相同,并最终归一处方剂量到PTV上,使V_(100)覆盖95%以上的PTV。通过剂量体积直方图和等剂量曲线分布图比较2组靶区和正常组织的剂量学参数。采用SPSS 24.0软件进行统计学分析。结果:BRSD计划组靶区的D_(98)、D_(max)、D_(mean)明显高于FSRT计划组,差异有统计学意义(P<0.05);2组的适形性指数、剂量梯度指数及正常组织的D_(mean)、V_(30)、V_(24)、D_(3 cc)比较,差异均无统计学意义(P>0.05);BRSD计划组的靶区内剂量分布更为密集。结论:BRSD计划模式在不增加或降低正常组织剂量的情况下,能够显著提升靶区吸收剂量,具有明显的剂量学优势。

Objective To explore the dosimetric effects of a self-developed planning mode of boundary range scattering dose(BRSD)on Cyberknife treatment of lung cancer brain metastases.Methods The positioning images of 15 patients with lung cancer brain metastases treated in the radiotherapy department of some institution from January 1,2021 to December 31,2021 were selected and introduced into Cyberknife Multiplan 4.0.3 treatment planning system.A fractionated stereotactic radiotherapy(FSRT)plan(as the FSRT planning group)and a BRSD plan(as the BRSD planning group)were developed for each patient.The FSRT planning group developed a plan for the planning target volume(PTV)in the conventional way,so that V_(100)covered more than 95%of the PTV;the BRSD planning group prepared a plan for the gross tumor volume(GTV)with the same parameter conditions as the FSRT planning group and the prescription dose was normalized to the PTV so that V_(100)covered more than 95%of the PTV.The dosimetric parameters of the target area and normal tissue of the 2 groups were compared by dose-volume histograms and isodose curves.Statistical analysis was performed using SPSS 24.0 software.Results The D_(98),D_(max)and D_(mean)in the target area of the BRSD planning group were significantly higher than those of the FSRT planning group,and the differences were statistically significant(P<0.05);the differences in the conformity index,dose gradient index,and D_(mean),V_(30),V_(24)and D_(3 cc)in normal tissue of the 2 groups were not statistically significant(P>0.05);the BRSD planning group gained a denser dose distribution when compared with the FSRT planning group.Conclusion The BRSD planning mode gains significant dosimetric advantage by enhancing the absorbed dose to the target area without increasing or decreasing the dose to normal tissue.