乳腺癌五种照射技术比较研究

Comparison Study on Irradiation Techniques for Breast Cancer

目的评价乳腺癌放疗时,适形、调强技术对保护正常组织和改善靶区剂量均匀度的作用。方法比较五种乳腺癌照射技术,包括常规切线照射技术、三维适形(3DCRT)切线照射技术、野中野照射技术、调强切线照射技术和调强五野照射技术。随机选择5位乳腺癌患者,为每位患者设计上述五种照射技术的治疗计划。处方剂量为46Gy/2Gy/23f。所有计划都使95%靶区体积达到处方剂量要求。分别比较他们的剂量分布、剂量体积直方图(DVH)、靶区剂量均匀度以及正常组织如肺、心脏所受剂量。结果五种技术靶区剂量均匀度的优劣:3D和调强技术比常规技术有改善趋势。但所有计划的靶区剂量分布方差分析无显著性差异(P=0.951)。3D技术和野中野技术各项指标值都基本相同。5野调强靶区剂量均匀度最佳。五种技术保护正常组织的效果:3D技术在正常组织的保护方面都优于常规技术。调强技术使患侧肺、心脏高剂量区体积降低,低剂量区增加。但使对侧肺和对侧乳腺的受照剂量略有增加。5野调强使正常组织受低剂量照射的范围显著增加。结论对于早期乳腺癌保乳术后放疗,在常规技术已达到较好疗效情况下,仍需要为提高患者生存质量、减少晚期并发症而努力。3DCRT技术在改善靶区剂量均匀度的同时,肺和心脏受照体积和受照剂量均低于常规技术;其计划时间和治疗时间与常规技术相近,因而可认为3DCRT是目前取代常规切线照射技术的较好选择。

Objective To evaluate the benefit of 3D CRT and IMRT in target dose uniformity and normal tissue sparing for breast cancer. Methods To compare 5 irradiation techniques for breast cancer including conventional technique with two wedged tangential fields, confonnal technique with two wedged tangential fields, field- in-field techique with two tangential fields, intensity - modulated radiation therapy with two tangential fields, intensity- modulated radiation therapy with five fields.For each of 5 randomly chosen patients, 5 plans were designed for five irradiation techniques. The prescribed dose was 46Gy/2Gy/23f, 95% of target volume receives this dose （ i. e. D95 = 46Gy） . We compared the dose distributions, dose volume histograms （DVH）, dose uniformity in target, and dose received by heart and ipsi- and contra - lateral lungs.Results Taget dose uniformity： The dose uniformity in target for two IMRT techniques, 3D CRT and Field in Field technique were improved in trend compared with conventional technique.But there were little differences in PTV＇ s coverage among all plans （ P = 0.591 ）. All character values for 3D CRT and Field in Field technique was similar.The target dose uniformity was best for 5 field IMRT. Normal tissue sparing： Normal tissue protection for 3D CRT were better than conventional technique. High dose area for ipsilateral lung and heart for IMRT were decreased while low dose areas were increased. Volume and Dose of con - lung and con - breast for IMRT were increased a little.Low dose area of normal tissue were greatly increased for 5 field IMRT. Conclusions For radiotherapy of early stage breast cancer after conservative surgery, conventional technique has showed satisfactory curative effect, but in order to improve patient＇ s living quality, less dose to lungs and heart, and better dose uniformity in target are desirable. 3D CRT technique improves both aspects than conventional technique. Planning time and delivery time are the same with conventional technique.Therefore, 3D CRT is the appropriate choice for current radiotherapy practice.