不同照射技术靶区及相关正常组织受量差异与剂量分布的比较

Comparison of dosimetry of target volume and normal tissue between IMRT and 3DCRT for postoperative patients with gastric cancer

目的比较胃癌术后患者调强放射治疗(intensity modulated radiation therapy,IMRT)与三维适形放射治疗(three dimensional conformal radiotherapy,3DCRT)两种放疗技术靶区及相关正常组织受量差异与剂量分布。方法 15例具有胃癌术后放疗适应证患者分别制定IMRT和3DCRT两种放疗计划,均采用6MV-X线。3DCRT采用分野技术,尽量减少肝脏及肾脏受量;IMRT根据处方剂量要求选择优化参数。靶区设定的处方剂量是至少95%计划靶体积(planning target volume,PTV)接受45.00 Gy,至少99%PTV接受42.75 Gy。利用剂量体积直方图比较不同照射技术靶区和相关正常组织受量差异与剂量分布。结果①靶区剂量学比较:IMRT的适形度及剂量均匀性均优于3DCRT(P<0.05),但两种放疗技术PTV剂量差异无统计学意义(P>0.05)。②正常组织受量比较:IMRT技术中左肾V15,正常肝V30,脊髓最大剂量,均优于3DCRT(P<0.05);而右肾的剂量分布,两种放疗技术差异无统计学意义(P>0.05)。结论胃癌术后IMRT,其靶区剂量的适形度、剂量均匀性优于3DCRT,并能够较好地保护周围正常组织。

Objective To compare the dosimetry of target volume and normal tissue between intensity-modulater radiotherapy （IMRT） and 3 dimensional conformal radiotherapy （3 DCRT） in postoperative patients with gastric cancer. Methods Plans of IMRT and 3DCRT were designed for 15 gastric cancer patients with indications for postoperative radiotherapy, respectively. In order to minimize the amount of liver and kidney, dose prescriptions were 45.00 Gy for 95 % planning target volume （PTV） and 42. 75 Gy for 99 % PTV. Dose volume histogram and dose distributions of the two regimes were compared. Results ① No significant difference in the PVT was found between IMRT and 3 DCRT. However, IMRT plan showed better dose uniformity and conformity （P 〈 0.05 ）. ② The V15 of left kidney, the V30 of liver and the maximum dose of spinal cord of IMRT were better than those of 3DCRT（P 〈 0. 05 ）. However, no significant difference in the V15 of right kidney was discovered between the two methods. Conclusions The uniformity and conformity of IMRT are better than that of 3DCRT,and IMRT was better than 3DCRT in protecting the surrounding normal tissue.