非共面野在早期非小细胞肺癌立体定向放射治疗方面的剂量学优势

Dosimetry advantage of stereotactic body radiation therapy of the non-coplanar technology application in the early stage of NSCLC

目的探讨非共面野调强放疗(IMRT)在早期非小细胞肺癌(NSCLC)立体定向放射治疗(SBRT)方面的剂量学特点和优势。方法选取10例早期NSCLC患者,分别制定9野共面IMRT计划和9野非共面IMRT计划,其中非共面计划包括5个共面野和4个非共面野。比较两个计划的全肺V2.5、V5、V20、V25、全肺平均照射剂量Dmean、健侧肺平均照射剂量Dmean,其他危及器官的比较包括:脊髓、心脏、食道、气管、胸壁的最大照射剂量和胸壁V30照射体积。同时比较两个计划的靶区适型性指数(CI)和均匀性指数(HI)。结果非共面野技术降低了全肺V20的照射体积(P=0.001),并降低了健侧肺的平均照射剂量Dmean(P=0.001),但在全肺V5的照射体积方面非共面野高于共面野(P=0.002)。非共面技术降低了脊髓、食道、气管、胸壁最大照射剂量和胸壁V30的照射体积(P=0.026,0.001,0.026,0.008,0.016),只有心脏的最大照射剂量非共面野高于共面野但差异无统计学意义(P=0.296)。靶区的适型性指数非共面野技术更好(P=0.036),均匀性指数两者差异无统计学意义(P=0.254)。结论在早期NSCLC立体定向放射治疗中,非共面野技术能有效降低肺组织和其他大部分危及器官的照射剂量并提高了靶区适型性指数,有降低相应并发症发生的可能性,相比于共面野有一定的剂量学优势。

Objective The objective of this study was to study the dosimetric characteristics and advan-tages of Non - coplanar IMRT techniques stereotactic body radiation therapy（ SBRT） in the early stage of NSCLC. Methods Ten patients were selected with early stage of NSCLC. Treatment planning designed 9 fields coplanar IMRT and 9 fields Non - coplanar IMRT,respectively. Non - coplanar plans include five coplanar fields and four non - coplanar fields. Two group patients, plans compared V2 5 ,V5 fV20 , V25 of the whole lung, the average expo-sure doses of the whole lung, and the average exposure doses of the contralateral lung. The comparison of the other OARs include ： spinal cord Dmax, heart Dmax, esophagus Dmax, trachea Dmax, chest wall Dmax and Vjq of chest wall. At the meantime,we compared the conformal index of PTV（CI）and the homogenization index of PTV（HI）. Results Non - coplanar plans reduced Vjq of the whole lung（P=0. 001 ）, the average exposure dose of the contralateral lung（P=0. 001 ）,but V5 of the whole lung non - coplanar plans were increased than that in coplanar plans （P = 0.002）. Non - coplanar technology reduce max dose of spinal cord, esophagus, trachea, chest wall and Vjq of chest wall（ P =0.026,0. 001 ,0.026,0. 008,0.016）. Heart Dmax of the non - coplanar plans was high in coplanar plans with no statistical significance difTerence（P = 0. 296）. The conformal index of PTV of the non - coplanar plans was better（ P =0.036）,there was no difference in the homogenization index of PTV（ P =0.254）. Conclu-sion The stereotactic body radiation therapy of the early stage of NSCLC, the non - coplanar technology can ef-fectively reduce exposure doses of the lung tissue and the other most OARs,also improve the conformal index of the PTV. The non - coplanar technology have possibility in reducing complications when compared with the copla-nar technology and therefore has certain dosimetry advantage.