乳腺癌保乳术后常规、三维适形和直接子野优化调强放疗技术剂量学评估

摘要

Objective: To compare the dose distribution and volume histogram(DVH) of the planning target volume(PTV) and organs at risk(OAR) between conventional radiation therapy(CR), three-dimensional conformal radiaton therapy(3D-CRT) and direct machine parameter optimization intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery.Methods: For each of 10 randomly chosen patients,3 plans were designed for 3 irradiation techniques.The prescribed dose was 50 Gy/2 Gy/25 f, 95％ of the planning target volume received this dose.The cumulated DVHs and 3D dose distributions of CR,3D-CRT and IMRT plans were compared.Results: Both the HI and CI of the PTV showed statistically significant difference between CR, 3DCRT and DMPO-IMRT (P=0.049,P=0.001).Compared with CR, 3DCRT showed smaller exposure dose to ipsilateral lung, contralateral breast and heart while DMPO-IMRT indicated larger exposure dose to ipsilateral lung (except for V20 and V30), contralateral breast and heart.In addition, DMPO-IMRT demonstrated an increase of exposure dose to ipsilateral lung (except for V30), contralateral breast and heart compared with 3DCRT.Conclusions: Compared with CR, 3D-CRT and DMPO-IMRT improved the homogeneity and conformity of the PTV.Meanwhile, 3DCRT reduced the irradiated volume of OARs at all dose levels listed in our study while DMPO-IMRT reduced the irradiated volume of OARs in high dose area but increased the irradiated volume of OARs in low dose area.%目的:比较乳腺癌保乳术后常规放疗(CR)、三维适形(3D-CRT)放疗、直接子野优化调强适形(DMPO-IMRT)放疗靶区剂量分布及危及器官受照体积等方面的差异.方法:随机选择10位乳腺癌患者,为每位患者设计上述三种照射技术的治疗计划.处方剂量为50Gy/2Gy/25次.所有计划都使95%靶区体积达到处方剂量要求.根据积分剂量体积直方图(DVH)比较靶区受量和相关正常器官受量的差异和剂量分布.结果:三种技术靶区均匀性指数(HI)和适形度指数(CI)差异均有显著性意义(P=0.049,P=0.001),其中尤以DMPO-IMRT的指标最佳.与CR相比,3DCRT降低了患侧肺、对侧乳腺和心脏在各个剂量区的受照体积,而DMPO-IMRT增大了患侧肺(V20、V30除外)、对侧乳腺和心脏的受照体积.与3DCRT相比,DMPO-IMRT增大了患侧肺(V<30除外)、对侧乳腺和心脏的受照体积.结论:与CR相比,3D-CRT和DMPO-IMRT改善了靶区的均匀性和适形度.与此同时,3DCRT降低了本研究中各个剂量区危及器官的受照体积,DMPO-IMRT在降低患侧肺高剂量受照体积的同时,增大了患侧肺、对侧乳腺、心脏的低剂量受照体积.