摘要目的 对比在左乳癌放射治疗中应用深吸屏气(DIBH-deep inspiration breath-hold)与自由呼吸两种方式(FB)的心脏等危及器官的受照射量,以及对心脏-胸壁接触距离(CCD)和心脏受照射量之间的相互关系.方法 对30例左乳癌患者分别进行DIBH和FB方式的CT扫描,然后使用治疗计划系统(TPS)进行剂量计算,通过使用剂量-体积直方图(DVH)对心脏、左前降支、左心室的剂量行分析,同时在基于FB的CT图像中分别对轴位心脏-胸壁接触距离(FB-CCDax)和矢状位心脏-胸壁接触距离(FB-CCDps)进行测量.结果 所有测量参数显示,采用DBIH技术的放射治疗中,心脏、左前降支、左心室的受照射量都远低于在FB中的各器官的剂量,心脏的平均照射剂量前者为0.8 Gy,后者为2.7 Gy,差异有统计学意义(P<0.01);左前降支的平均照射剂量前者为4.0 Gy,后者为12.7 Gy(P<0.001);左心室的平均照射剂量前者为1.2 Gy,后者为3.6 Gy(P<0.01).在DIBH和FB放射治疗中,心脏、左前降支和左心室的平均照射剂量都与FB-CCDps有相关性,而与FB-CCDax没有相关性.结论 在不丢失靶区剂量的情况下,DIBH方式是一种行之有效且简单的能够降低心脏受照射量的治疗技术.FB-CCDps是一个潜在的心脏受照射量的预测因子,FB-CCDps距离越长,则心脏的受照射量就越高.通过此次研究发现,至少70%的左侧乳腺癌患者会从DIBH中获益而使得心脏等正常结构的受照射量降低,因此,应该将DIBH做为日常的临床应用.

abstractsObjective To compare the exposure to heart and other organs of the application of DIBH (deep inspiration breath-hold)and FB(free breath)in the left breast cancer radiotherapy,and the relationship between CCD(cardiac contact distance)and heart dose was analyzed.Methods Thirty patients with left breast cancer were examined with CT scans using DIBH and FB respectively,and then the dose was calculated by TPS(treatment planning system).The dose of heart,left anterior descending branch and left ventricle were analyzed by DVH(dose volume histogram).FB-CCDax(Axial cardiac chest wall contact distance)and FB-CCDps(sagittal heart chest wall contact distance)in CT images were measured based on FB.Results The parameters showed that,in radiotherapy with the application of DBIH technology,the irradiated volume of heart, left anterior descending branch(LAD),left ventricle(LV)of were significantly lower than that in the organs in the FB,the mean dose(Dmean)of heart of the former was 0.8 Gy,compared with 2.7 Gy in the latter one(P<0.005).The Dmean of LAD was 4.0Gy,compared with 12.7Gy in the latter one(P<0.001); The Dmean of LV was 1.2Gy,compared with 3.6Gy in the latter one(P<0.005).In the DIBH and FB radiotherapy,the Dmean of the heart,left anterior descending branch and left ventricle was correlated with FB-CCDps,but not with FB-CCDax.Conclusion DIBH is a simple treatment technique that can effectively reduce the cardiac radiation dose without loss of target dose.FB-CCDps is a potential predictor of cardiac exposure,and the longer the FB-CCDps distance is,the higher the cardiac dose is.The study found that at least 70% of patients with left breast cancer would benefit from DIBH and reduce the radiation exposure to normal cardiac structures,so DIBH should be used as a routine clinical application.