Neal A J, Torr M, Helyer S, Yarnold J R
Department of Physics, Royal Marsden Hospital, Sutton, Surrey, UK.
Radiother Oncol. 1995 Mar;34(3):210-8. doi: 10.1016/0167-8140(95)01521-h.
The aim of this study was to evaluate the effect of breast size on dose heterogeneity. Twenty women underwent a planning CT scan of the thorax. A three-dimensional treatment plan was devised for each patient using a standard technique of isocentric medial and lateral wedged tangential fields. Three-dimensional dose distributions were derived using an equivalent path length (EPL) inhomogeneity correction and cumulative dose-volume histogram (DVH) data calculated for the breast. Analysis of the DVHs for each patient reveals that 0.2-23.8% of the breast received an absorbed dose outside the desired 95-105% of that prescribed at the isocentre. The degree of dose heterogeneity was most strongly correlated with breast volume (r = 0.70, 95% confidence interval (C.I.) 0.37-0.87). There was also a positive correlation for breast dose heterogeneity versus brassière (bra) cup size (Spearman rank correlation rho = 0.62), breast area (r = 0.39, 95% C.I. -0.06-0.71) and chest wall separation (r = 0.31, 95% C.I. -0.15-0.66). We conclude that breast size is an important determinant of dose heterogeneity within the breast.
本研究的目的是评估乳房大小对剂量不均匀性的影响。20名女性接受了胸部的计划CT扫描。使用等中心内外楔形切线野的标准技术为每位患者设计三维治疗计划。利用等效路径长度（EPL）不均匀性校正和为乳房计算的累积剂量体积直方图（DVH）数据得出三维剂量分布。对每位患者的DVH分析显示，0.2%至23.8%的乳房接受的吸收剂量超出了等中心处规定剂量的95%至105%。剂量不均匀程度与乳房体积的相关性最强（r = 0.70，95%置信区间（C.I.）0.37 - 0.87）。乳房剂量不均匀性与胸罩罩杯尺寸（Spearman等级相关性rho = 0.62）、乳房面积（r = 0.39，95% C.I. -0.06 - 0.71）和胸壁间距（r = 0.31，95% C.I. -0.15 - 0.66）之间也存在正相关。我们得出结论，乳房大小是乳房内剂量不均匀性的一个重要决定因素。
