儿童神经母细胞瘤三维适形放射治疗与调强放射治疗剂量学比较

Dosimetric comparison of three- dimensional conformal radiotherapy and intensity modulated radiotherapy for pediatric neuroblastoma

目的:评价调强放射治疗计划与三维适形计划对于儿童腹部神经母细胞瘤剂量学上的差异。方法:选取10例儿童腹部神经母细胞瘤图像,分别制定三维适形计划和调强放射治疗计划,处方剂量为21.6 Gy/12 Fx,比较正常组织肾脏和肝脏的剂量。同时比较靶区的剂量、均匀性指数(Homogeneity Index,HI)和适形指数(Conformity Index,CI)。结果:根据剂量体积直方图,评估两种治疗方式下覆盖靶区95%体积的剂量,靶区的HI以及近似最大剂量D_(2%),近似最小剂量D_(98%)无显著差异,调强放射治疗计划的靶区CI明显优于三维适形放射治疗。对于正常组织,使用三维适形放射治疗肝脏的V_8和V_(15)分别为40.3%±19.1%和25.7%±16.7%,使用调强放射治疗肝脏的V_8和V_(15)分别为45.5%±17.5%和16.9%±13.3%;三维适形放射治疗左肾脏的V_(15)和V_(18)分别为37.4%±20.4%和21.6%±12.2%,使用调强放射治疗左侧肾脏的V_(15)和V_(18)分别为15.3%±5.2%和5.7%±3.6%;三维适形放射治疗右肾脏的V_(15)和V_(18)分别为29.4%±16.4%和20.6%±14%,使用调强放射治疗右肾脏的V_(15)和V_(18)分别为13.3%±7.4%和5.9%±3.9%。两种治疗方式评估肝脏的剂量,无显著差异,评估肾脏的剂量,调强放射治疗明显更好保护了肾脏。结论:使用调强放射治疗技术靶区的剂量更加适形,并可以更好地保护肾脏,但是由于照射范围中低剂量区范围较大,在儿童患者中使用仍然需要谨慎。

Objective To evaluate the dosimetric difference between intensity modulated radiotherapy （IMRT） and three- dimensional conformal radiotherapy （3DCRT） for pediatric neuroblastoma. Methods Images of 10 patients with pediatric neuroblastoma in our department were selected. Both 3DCRT and IMRT plans were respectively designed for each patient, and the prescribed dose was 21.6 Gy/12 Fx. The dose of normal tissues of kidneys and liver, target volume dose, homogeneity index （HI）, and conformity index （CI） were compared. Results Dose volume histogram indicated that no significant differences were found in the dose coverage of 95% target volume, HI, approximate maximum dose D2%, and approximate minimum dose D98%, and that the CI of IMRT was obviously better than that of 3DCRT. The V8 and V15 of liver, and V,5 and V,8 of the left kidney, and the V, and V,, of the right kidney of 3DCRT plan were respectively 40.3%±19.1%, 25.7%± 16.7%, 37.4%±20.4%, 21.6%± 12.2%, 29.4%± 16.4%, and 20.6%±14%, while those of IMRT plan were respectively 45.5%±17.5%, 16.9%±13.3%, 15.3%±5.2%, 5.7%±3.6%, 13.3%±7.4%, and 5.9%±3.9%. No significant differences werefound in the dose of liver between IMRT and 3DCRT. The dose comparison of kidneys showed IMRT had a better protective effect on kidneys. Conclusion Compared with 3DCRT, IMRT for pediatric neuroblastoma has a better CI, and a better protective effect on kidneys. However, IMRT should still be used carefully in pediatric patients for the larger low dose volumes in the radiation volume.