Schönecker S, Heinz C, Söhn M, Haimerl W, Corradini S, Pazos M, Belka C, Scheithauer H
Department of Radiation Oncology, University Hospital of Ludwig-Maximilian-University, Ziemssenstr. 1, 80336, Munich, Germany.
Strahlenther Onkol. 2016 Nov;192(11):750-758. doi: 10.1007/s00066-016-1039-z. Epub 2016 Sep 8.
The radiation dose received by the heart during adjuvant left-sided breast irradiation plays a crucial role in development of late toxicity. Although the absolute risk of cardiotoxicity can be reduced with modern irradiation techniques, cardiotoxic chemotherapy increases the risk of late damage. Thus, the radiation dose to the heart should be minimized. This study evaluated the influence of different amplitudes of inspiration breath hold (IBH) during simulated left-sided breast irradiation on cardiac doses compared to free breathing (FB).
CT data of 11 lung cancer patients were retrospectively used as left-sided pseudo-breast cancer cases. Two CT scans were used, one during IBH and one during FB, and two treatment plans were generated. Relevant heart, lung, and left anterior descending artery (LAD) parameters were derived from dose-volume histograms. The normal tissue complication probabilities (NTCPs) for the heart were calculated based on the relative seriality model. Inspiration depth was quantified using chest volume and diameter, and correlated thereafter to a possible sparing of heart tissue.
Mean reduction of heart dose for IBH compared to FB was 40 % (1.65 vs. 0.99 Gy; p = 0.007). Maximum dose to the heart and LAD could be decreased by 33 % (p = 0.011) and 43 % (p = 0.024), respectively. The mean anteroposterior shift was 5 mm (range 0.9-9.5 mm). Significant negative correlations between the relative change in LAD mean dose and the mean thoracic diameter and volume change, as well as with the absolute change in thoracic diameter were seen. The NTCP for cardiac mortality could be decreased by about 78 % (p = 0.017).
For left-sided breast cancer patients, cardiac doses can be significantly decreased with tangential irradiation and IBH.
辅助性左侧乳腺放疗期间心脏所接受的辐射剂量在迟发性毒性的发生中起着关键作用。尽管现代放疗技术可降低心脏毒性的绝对风险，但心脏毒性化疗会增加迟发性损伤的风险。因此，应尽量减少心脏的辐射剂量。本研究评估了模拟左侧乳腺放疗期间不同吸气屏气（IBH）幅度与自由呼吸（FB）相比对心脏剂量的影响。
回顾性地将11例肺癌患者的CT数据用作左侧假乳腺癌病例。使用了两次CT扫描，一次在吸气屏气期间，一次在自由呼吸期间，并生成了两个治疗计划。从剂量体积直方图中得出相关的心脏、肺和左前降支动脉（LAD）参数。基于相对串联模型计算心脏的正常组织并发症概率（NTCPs）。使用胸部体积和直径对吸气深度进行量化，然后将其与心脏组织的可能保留情况相关联。
与自由呼吸相比，吸气屏气时心脏剂量平均降低40%（1.65对0.99 Gy；p = 0.007）。心脏和左前降支动脉的最大剂量分别可降低33%（p = 0.011）和43%（p = 0.024）。前后平均移位为5 mm（范围0.9 - 9.5 mm）。观察到左前降支动脉平均剂量的相对变化与平均胸廓直径和体积变化以及胸廓直径的绝对变化之间存在显著负相关。心脏死亡的正常组织并发症概率可降低约78%（p = 0.017）。
对于左侧乳腺癌患者，采用切线照射和吸气屏气可显著降低心脏剂量。
