Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109-5010, USA.
Int J Radiat Oncol Biol Phys. 2013 Mar 15;85(4):959-64. doi: 10.1016/j.ijrobp.2012.08.002. Epub 2012 Sep 27.
To quantify cardiac radiation therapy (RT) exposure using sensitive measures of cardiac dysfunction; and to correlate dysfunction with heart doses, in the setting of adjuvant RT for left-sided breast cancer.
On a randomized trial, 32 women with node-positive left-sided breast cancer underwent pre-RT stress single photon emission computed tomography (SPECT-CT) myocardial perfusion scans. Patients received RT to the breast/chest wall and regional lymph nodes to doses of 50 to 52.2 Gy. Repeat SPECT-CT scans were performed 1 year after RT. Perfusion defects (PD), summed stress defects scores (SSS), and ejection fractions (EF) were evaluated. Doses to the heart and coronary arteries were quantified.
The mean difference in pre- and post-RT PD was -0.38% ± 3.20% (P=.68), with no clinically significant defects. To assess for subclinical effects, PD were also examined using a 1.5-SD below the normal mean threshold, with a mean difference of 2.53% ± 12.57% (P=.38). The mean differences in SSS and EF before and after RT were 0.78% ± 2.50% (P=.08) and 1.75% ± 7.29% (P=.39), respectively. The average heart Dmean and D95 were 2.82 Gy (range, 1.11-6.06 Gy) and 0.90 Gy (range, 0.13-2.17 Gy), respectively. The average Dmean and D95 to the left anterior descending artery were 7.22 Gy (range, 2.58-18.05 Gy) and 3.22 Gy (range, 1.23-6.86 Gy), respectively. No correlations were found between cardiac doses and changes in PD, SSS, and EF.
Using sensitive measures of cardiac function, no clinically significant defects were found after RT, with the average heart Dmean <5 Gy. Although a dose response may exist for measures of cardiac dysfunction at higher doses, no correlation was found in the present study for low doses delivered to cardiac structures and perfusion, SSS, or EF.
使用心脏功能的敏感指标来量化心脏放射治疗（RT）的暴露情况，并在左侧乳腺癌辅助 RT 中，将功能障碍与心脏剂量相关联。
在一项随机试验中，32 名患有淋巴结阳性左侧乳腺癌的患者接受了 RT 前应激单光子发射计算机断层扫描（SPECT-CT）心肌灌注扫描。患者接受了 50 至 52.2 Gy 的乳房/胸壁和区域淋巴结 RT。RT 后 1 年进行重复 SPECT-CT 扫描。评估灌注缺陷（PD）、总和应激缺陷评分（SSS）和射血分数（EF）。量化心脏和冠状动脉的剂量。
RT 前后 PD 的平均差异为 -0.38% ± 3.20%（P=.68），没有明显的缺陷。为了评估亚临床影响，还使用低于正常平均值 1.5SD 的阈值来检查 PD，平均差异为 2.53% ± 12.57%（P=.38）。RT 前后 SSS 和 EF 的平均差异分别为 0.78% ± 2.50%（P=.08）和 1.75% ± 7.29%（P=.39）。平均心脏 Dmean 和 D95 分别为 2.82 Gy（范围，1.11-6.06 Gy）和 0.90 Gy（范围，0.13-2.17 Gy）。左前降支的平均 Dmean 和 D95 分别为 7.22 Gy（范围，2.58-18.05 Gy）和 3.22 Gy（范围，1.23-6.86 Gy）。心脏剂量与 PD、SSS 和 EF 的变化之间没有相关性。
使用心脏功能的敏感指标，RT 后未发现明显缺陷，平均心脏 Dmean <5 Gy。尽管在更高剂量下可能存在心脏功能障碍的剂量反应，但在本研究中，未发现与心脏结构和灌注、SSS 或 EF 相关的低剂量之间存在相关性。
