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目的 应用三维治疗计划系统评价肺癌不同的照射方法 ,以明确肺癌三维适形放射治疗的优势。方法 选用 1 3例ⅢA、ⅢB期非小细胞肺癌病例 ,采用Cadplan 6 .0 .8三维治疗计划系统设计放射治疗计划 ,每例均做 3个计划 ,分别为常规、常规加适形和适形放射治疗计划 ,计划的总剂量均为 66Gy。用剂量体积直方图 (DVH)比较靶区剂量和正常组织的受照射剂量的差异。结果 3种治疗计划均能满足靶区剂量要求 ,剂量变化差异无显著性意义。常规、常规加适形和适形放射治疗计划的照射适形指数分别为 0 .1 3、0 .2 4和 0 .35 ;全肺接受≥ 2 0Gy照射的体积百分比的均数分别为 32 %、2 6 %和 2 5 % ;脊髓的最大剂量分别为 42、49和 33Gy ;食管照射≥ 50Gy的体积百分比的均数分别为32 %、34 %和 2 2 % ;心脏平均剂量的均数分别为 1 8、1 5和 1 2Gy。结论 肺癌常规放射治疗设野方法基本能满足靶区的剂量学要求 ,然而正常组织的受照剂量明显高于其他 2种治疗计划。三维适形放射治疗的主要优势在于减少正常组织的受照剂量。
Objective To evaluate the advantages of three-dimensional conformal radiotherapy for lung cancer by using three-dimensional treatment planning system to evaluate different irradiation methods of lung cancer. Methods A total of 13 cases of stage ⅢA and ⅢB non-small cell lung cancer were selected. Radiotherapy plans were designed by Cadplan 6 .0 .8 three-dimensional treatment plan system. Each case had 3 plans, which were routine, conventional and conformal and conformal Radiation therapy plan, the total planned dose is 66Gy. Dose volume histograms (DVH) were used to compare the difference between the target dose and the irradiated dose of normal tissue. Results All the three treatment plans could meet the target dosage requirements, but no significant difference was observed in dose changes. Conventional, conformal and conformal radiotherapy plans irradiation conformal index were 0.13,0.24 and 0.35; the whole lung accepted ≥ 20Gy irradiation volume percentage mean were 32% , 26% and 25% respectively; the maximum dose of spinal cord was 42, 49 and 33 Gy, respectively; the volume percentage of esophageal irradiation ≥ 50 Gy was 32%, 34% and 22% respectively; 1 8, 1 5 and 1 2Gy. Conclusion The routine radiotherapy field method of lung cancer can basically meet the dosimetry requirements of the target area, however, the dose of the normal tissue is obviously higher than the other two kinds of treatment plans. The main advantage of 3D conformal radiotherapy is the reduction of the dose of normal tissue.