胃癌术后割裂野单中心半野适形放疗的剂量学研究

Dosiology about 3D-conformal radiotherapy consisting of a split-field and mono-isocentric semi field technique for postoperative gastric cancer patients

目的：对比研究胃癌术后患者辅助割裂野单中心半野适形放疗（3D-SF-CRT）、三维适形放疗（3D-CRT）及前后对穿野常规放疗（AP-PA）的剂量学特点。方法：在放疗计划系统为有术后辅助放疗适应证的胃癌患者15例设计相同计划靶体积（PTV）下的3种放射治疗方案,处方剂量均为45 Gy,根据剂量体积直方图（DVH）计算并比较3种放疗方法各参数的标准差。结果：3种放疗技术的计划靶区的V95、D95差异无统计学意义（P值分别为0.521和0.241）,2种适形放疗技术的适形指数差异无统计学意义（P=0.189）,但均高于AP-PA,P=0.02。3D-SFCRT、3D-CRT和AP-PA的脊髓最大点剂量分别为（33.24±0.45）、（35.01±0.48）和（51.90±0.92）Gy,P=0.06。3D-SFCRT的双肾V20~V45均小于其他2种放疗技术,P〈0.05。3D-SFCRT的肝脏V25~V45比3D-CRT高,但差异均无统计学意义,P=0.261。3D-SFCRT的右肾T5/5明显低于3D-CRT,P值分别为0.001和0.008;在左肾、脊髓及肝脏,差异无统计学意义,P值均〈0.05;与AP-PA相比,3D-SF-CRT的脊髓、双肾的T5/5明显为低,P值均〈0.05;在肝脏两者类似,P=0.261。结论：胃癌术后辅助放疗,与常规适形放疗技术相比,应用割裂野单中心半野适形照射技术能在确保PTV获得满意剂量分布的同时,更好地保护脊髓及双侧肾脏,值得推广。

OBJECTIVE：To compare the features of dosiology among 3D split-field conformal radiaotherapy（3D-SFCRT）,3D conformal radiaotherapy（3D-CRT） and parallelopposed anteroposterior-posteroanterior field radiaotherapy（AP-PA）.METHODS： A total of 15 cases of postoperative gastric cancer patients who had indications of adjuvant radiaotherapy were involved.DVHs of 3D-SFCRT,3D-CRT and AP-PA of evrey case were separately acquired from treatment planning system（TPS）.Each prescribed dose of any radiaotherapy technique was 45 Gy.Then the standard deviations of some parameters were compared among the three techniques.RESULTS： V95 and D95 about PTV had no difference among the three techniques（P=0.521;P=0.241）.There was no difference of CIs between the two conformal techniques（P=0.189）,but the conformal techniques had better PTV fitness than the AP-PA one（P=0.02）.The maximum dose points of spinal cord in 3D-SFCRT,3D-CRT,and AP-PA were（33.24±0.45）,（35.01±0.48） and（51.90±0.92） Gy,respectively,and there was a difference between any two techniques（P=0.06）.V20-V45 of kidneys in 3D-SFCRT was less than that in the other two（P0.05）.V25-V45 of liver was similar among the three techniques（P=0.261）.T5/5 of right kidney was obviously lower in 3D-SFCRT than that in 3D-CRT（P=0.001;P=0.008）,but T5/5 of spinal cord,left kidney or liver was all no difference between the two conformal methods（P0.05）.Compared with AP-PA,T5/5 of 3D-SFCRT in spinal cord and kidneys,were lower（P0.05）,and similar in liver（P=0.261）.CONCLUSION： There are similar dose distribution of PTV,less dose of spinal cord and kidneys in 3D-SFCRT than that in 3D-CRT in gastric cancer patients that accept adjuvant postoperative randiaotherapy,therefore,3D split-field conformal radiaotherapy technique can be promoted.