肺部直径<5cm病灶适形调强放疗及“陀螺刀”放疗的剂量分布比较

A study of dose distribution comparison between IMRT and Gyroknife treatment plans for < 5cm lung lesions

目的分析陀螺刀和适形调强放射治疗(intensity modulated radiotherapy,IMRT)两种照射方法治疗直径<5cm肺部病灶的计划肿瘤靶区(planning target volume,PTV)和危及器官(organs at risk,OARs)剂量学分布特点。方法对16例原发性非小细胞肺癌及肺转移癌患者(共20个病灶)分别设计陀螺刀和IMRT放射治疗计划,采用剂量体积直方图(dose-volume histogram,DVH)对2种放疗计划的肿瘤计划靶区和OAR剂量学相关参数进行评估,分析2种放疗计划在直径<5cm肺部病灶剂量学差异。结果陀螺刀计划肿瘤靶区平均值(mean dose of PTV,PTVDmean),计划靶区剂量最大值(maximum dose of PTV,PTVDmax)更高,而两种放疗计划的计划靶区剂量最小值(minimum dose of PTV,PTVDmin)差异无显著性,适形指数(conformal index,CI)IMRT更优,而均匀指数(homogeneity index,HI)陀螺刀更高,全肺V5,V10,V20以及全肺平均剂量比较,陀螺刀和IMRT无显著差异,而陀螺刀的V30更高;对患侧肺比较,陀螺刀的V5,V10和患侧肺平均剂量显著高于IMRT,而患侧肺陀螺刀的V20和V30与IMRT类似;健侧肺比较,IMRT与陀螺刀相比,IMRT健侧肺低剂量区高于陀螺刀,主要表现在V5和健侧肺平均剂量。脊髓和食管的最大受量IMRT和陀螺刀计划差异无显著性(P<0.05)。结论陀螺刀和适形调强放疗计划在治疗肺部<5cm病灶时,肿瘤靶区剂量和危及器官剂量分布均能达到预设要求,陀螺刀放射治疗计划PTVDmean剂量较大,健侧肺组织接受的照射量更低,而IMRT计划肿瘤靶区适形度高。

Objective To analyze the dose distribution of Co-60 gyro knife and intensity modulated radiotherapy therapy of<5 cm lung lesions,and to compare the differences between the above two kind of treatment planning system of PTV and OARs.Methods A total of 16 patients with 20<5 cm lung lesions (including nonsmall cell lung cancer and pulmonary metastatases) were given two plans of gyro knife and IMRT plan respectively.The two plans were evaluated by DVH of PTV and OARs.Results PTVDmean and PTVDmax of Gyro knife plan were significantly higher than those of IMRT plan ( P< 0.05),while there was no difference with PTVDmin.CI was higher in IMRT while HI was higher in Gyroknife.There was no significant difference in V5,V10,V20 and average lung dose in the whole lungs between the two plans and V30 was more higher in Gyrokinfe.In the suffered lung,the value of V5,V10 and average lung dose were higher in Gyroknife than those of IMRT and with no difference in V20 and V30.For the healthy lung,the low dose volume was more higher in IMRT plan with higher V5 and average lung dose.There was no difference in the largest dose in spinal cord and esophagus ( P> 0.05).Conclusion Gyroknife and IMRT plans can both meet the requirement of planning tumor volume dose distribution and OARs dose constraints.Gyro knife plan has higher dose of PTVDmean and lower dose in the healthy lung,and IMRT plan has higher PTV conformal index.