摘要目的 比较肺部肿瘤调强放疗(IMRT)和立体定向放疗(SRT)的大分割治疗计划的剂量分布特点,为临床治疗优选方案提供依据.方法 对近1年内收治的16例采用大分割IMRT的肺部肿瘤(非小细胞肺癌6例和肺转移癌lO例)患者设计处方剂量与治疗间隔相似的SRT计划,采用剂量体积直方图评价IMRT和SRT计划对靶区和正常组织照射剂量等以及适形指数(CI)和不均匀指数(HI).结果 患者采用大分割IMRT和SRT计划时PTV接受的平均剂量分别为6282.1 cGy和6340.6 cGy(t=-0.93,P>0.05),均一化剂量分别为6366.7 cGy和6246.8 cGy(t=-1.18,P>0.05),CI平均值分别为0.78和0.57(t=2.77,P<0.05),HI平均值分别为1.12和1.32(t=-4.38,P<0.01).IMRT和SRT计划的平均全肺组织受照剂量分别为(492.4±368.5)cGy和(310.0±73.1)cGy(t=1.68,P>0.05),全肺V20分别为6.9%±2.1%和4.2%±1.9%(t=3.30,P<0.01).IMRT和SRT计划的心脏和脊髓平均受照剂量无差别.结论 PTV最大径<4.7 cm、靶体积<57 cm3、靶区呈圆形或类圆形时,SRT靶区剂量与大分割IMRT接近并可满足临床要求;SRT计划正常肺组织受照剂量低于大分割IMRT计划.

abstractsObjective To compare the characteristics of dose distribution between hypofractionated intensity modulated radiotherapy (IMRT) and hypofractionated stereotactic radiotherapy (SRT) plans in lung tumor and to select an optimal clinical approach. Methods SRT plans were designed for 16 patients with lung tumors who had received IMRT between April 2007 and April 2008. The dose distribution of target volume and normal tissues, conformal index (CI) and heteregenous index (HI) were analyzed using the dose-volume histogram (DVH) for the IMRT and SRT plans. Results The mean dose and equivalent uni-form dose of planning target volume (PTV) in IMRT were similar to those in SRT. SRT had significantly better CI and HI than IMRT (t = 2.77, P < 0.05 and t = - 4.38, P < 0.01 ). The mean lung dose of IMRT and SRT was (492.4 ±368.5) cGy and ( 310.0 ± 73.1 ) cGy, respectively ( t = 1.68, P > 0.05 ). The lung V20 of IMRT and SRT was 6.9% ± 2.1% and 4.2%± 1.9%, respectively ( t = 3.30, P < 0.01 ). No sig-nificant differences were found in the mean dose to the heart or the spinal cord between IMRT and SRT. Conclusions When PTV is less than 57 cm3 or the long diameter of tumor is less than 4.7 cm, hypofrac-tionated SRT has similar dose distribution to hypofractionated IMRT, while the lung dose was lower in the former.