目的:比较肺癌三维适形放疗(3DCRT)两种治疗方案之间的差异,以期减少正常组织损伤.方法:选择9例病理证实的原发性肺癌,为每个病例设计两套治疗计划,计划1、计划2,每套计划均采用5个非等角共面野等中心照射,要求计划1和计划2在靶区(GTV、CTV)内的剂量分布是等同的,但每套计划的射野人射方向彼此不同.通过添加不同楔形角度的楔形板、调整射野入射的方向、权重等,使计划1与计划2满足临床要求.在治疗计划系统(TPS)中模拟,方案1:计划1与计划2独立照射,处方剂量皆为60 Gy,每次2 Gy；方案2:计划1与计划2每天轮照,处方剂量皆为30 Gy,每次2Gy.将方案1与方案2比较.结果:两方案治疗计划GTV的Dmax、Dmin和Dmean的均数没有显著性差异(P＞0.05)；HI、CI值的均数没有显著性差异(P＞0.05)；脊髓Dmax、食管V50、心脏V40,两肺V20、V5、Dmean的均数没有显著性差异(P＞0.05).但是方案2的肺正常组织并发症概率(NTCP)小于方案1,有显著性差异(P＜0.05).结论:方案2每天轮照,因卷入射野内的正常组织有一天以上的休息和对损伤的修复时间,在肿瘤剂量一定的情况下,可减少正常组织损伤.%Objective: To compare with difference of two radiotherapy schemes in three-dimensional conformal radiotherapy (3DCRT )for lung cancer, in order to reduce the normal tissue damage. Methods: To choose 9 cases of patients with lung turner in lung, each case of patient was designed two groups radiotherapy plan, plan 1, plan 2, each plan by five coplanar fields irradiation of source axis distance, designning Plan, to require the dose distribution of plan 1 and plan 2 in target area (GTV, CTV) is equal, but the incidence direction of each plan irradiation fiel is different from each other. By adding different angle wedge,adjusting the incidence direction of irradiation fiel, weights etc, make the plan 1 and plan 2 satisfy clinical requirements. Simulation treatment in TPS, scheme 1: plan 1, plan 2 independent irradiation, prescribed dose is 60 Gy, 2 Gy each time; scheme 2: plan 1, plan 2 was taken turnes irradiation everyday, the prescribed dose of plan 1 and plan 2 was set 30 Gy, 2 Gy each time. To compare the dose distribution of scheme 1 and scheme 2. Results: There was no difference in Dmax , Dmin and Dmean, of GTV in two schemes (P> 0.05); There was no difference in value of HI and CI (P> 0.05). There was no difference in Dmax of Spinal cord, heart V40, esophagus V50, there was no difference in the V20 and V5 of two lungs, Dmean of two lungs (P> 0.05). NTCP of schemes2 is littler man schemes 1,NTCP of schemesl and schemes2 are significant differences (P<0.05). Conclusions: The scheme 2 is taken turnes irradiation everyday, because normal tissue is involved over one day of rest and repair time of injury, when tumor dose is no change, it can decrease normal tissue damage.
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