Department of Oncotherapy, University of Szeged , Szeged , Hungary.
Acta Oncol. 2014 Jan;53(1):58-64. doi: 10.3109/0284186X.2013.781674. Epub 2013 Apr 2.
Prone positioning has been found feasible and appropriate for the reduction of radiation exposure of the lungs, but its effects on the heart dose remain controversial. Individual anatomical features were sought for the selection of optimal treatment positioning.
In 138 left-sided breast cancer cases awaiting postoperative whole-breast radiotherapy, conformal radiotherapy plans were generated in both prone and supine positions.
The radiation doses to the left anterior descending coronary artery (LAD) and heart in the two positions differed individually, and were strongly related to the body mass index (BMI). Image fusion of the CT scans revealed that prone positioning was detrimental if the heart was situated distant from the chest wall in the supine position, but moved to the chest wall in the prone position. For characterization of the geography of the heart and the breast, the median distance between the LAD and the chest wall (dmedian), and the heart area included in the radiation field on a single CT scan at the middle of the heart in the supine position (Aheart) proved most appropriate.
A validated statistical model, utilizing the BMI, dmedian and Aheart, permits individualized positioning for maximum heart protection.
俯卧位已被证明在减少肺部辐射暴露方面是可行且合适的，但它对心脏剂量的影响仍存在争议。为了选择最佳的治疗体位，需要考虑个体的解剖特征。
在 138 例左侧乳腺癌术后接受全乳放疗的患者中，分别在俯卧位和仰卧位生成适形放疗计划。
两种体位下左侧前降支冠状动脉（LAD）和心脏的辐射剂量存在个体差异，且与体重指数（BMI）密切相关。CT 扫描的图像融合显示，如果心脏在仰卧位时远离胸壁，而在俯卧位时移向胸壁，则俯卧位对心脏不利。为了描述心脏和乳房的位置关系，LAD 与胸壁之间的中位数距离（dmedian）和仰卧位时心脏中部单次 CT 扫描中包含在照射野内的心脏面积（Aheart）被证明是最合适的。
利用 BMI、dmedian 和 Aheart，可以建立一个经过验证的统计模型，实现个体化的体位定位，以最大程度地保护心脏。
