Department of Radiation Oncology, University of Texas-Southwestern, Moncrief Radiation Oncology Center, Dallas, Texas.
School of Medicine, University of Texas-Southwestern, Dallas, Texas.
Pract Radiat Oncol. 2017 Nov-Dec;7(6):e361-e367. doi: 10.1016/j.prro.2017.04.006. Epub 2017 Apr 13.
The purpose of this study was to evaluate the utility of moderate deep inspiration breathhold (mDIBH) in reducing heart exposure in left breast cancer patients who have unfavorable cardiac anatomy and need internal mammary lymph node (IMLN) radiation therapy (RT).
We used maximum heart distance (MHD), defined as the maximum distance of the heart within the treatment field, >1 cm as a surrogate for unfavorable cardiac anatomy. Twenty-two left breast cancer patients with unfavorable cardiac anatomy requiring IMLN-RT underwent free-breathing (FB) and mDIBH computed tomography simulation and planning. Three-dimensional partially wide tangents (3D-PWTs) and intensity modulated RT plans were generated. Dose-volume histograms were used to compare heart and lung dosimetric parameters. Duration of treatment delivery was recorded for all fractions.
MHD decreased significantly in mDIBH scans. mDIBH significantly reduced mean heart dose (222.7 vs 578.4 cGy; P < .0001) and percentage of left lung receiving doses ≥20 Gy (V20; 31.93 vs 38.41%; P = .0006) in both 3D-PWT and intensity modulated RT plans. The change in MHD after breathhold reliably predicted mean heart dose reduction after mDIBH. Radiation was effectively delivered in 11.31 ± 3.40 minutes with an average of 10.06 ± 2.74 breathholds per fraction.
mDIBH is efficient and can effectively decrease mean heart dose in patients with unfavorable cardiac anatomy who need IMLN-RT, thus simplifying planning and delivery for them. The reduction in mean heart dose is proportional to the reduction in maximum heart distance.
本研究旨在评估中度深吸气屏气（mDIBH）在减少需要内乳淋巴结（IMLN）放疗（RT）且心脏解剖结构不良的左乳腺癌患者心脏照射的有效性。
我们使用最大心脏距离（MHD），定义为心脏在治疗野内的最大距离> 1cm 作为心脏解剖结构不良的替代指标。22 例需要 IMLN-RT 的心脏解剖结构不良的左乳腺癌患者进行了自由呼吸（FB）和 mDIBH 计算机断层扫描模拟和计划。生成了三维部分宽切线（3D-PWT）和调强放疗计划。使用剂量体积直方图比较心脏和肺剂量学参数。记录了所有分次的治疗时间。
mDIBH 扫描时 MHD 显著降低。mDIBH 显著降低了 3D-PWT 和调强放疗计划的平均心脏剂量（222.7 与 578.4 cGy；P <.0001）和左肺接受剂量≥20 Gy 的百分比（V20；31.93 与 38.41%；P =.0006）。屏气后 MHD 的变化可靠地预测了 mDIBH 后平均心脏剂量的降低。11.31±3.40 分钟内有效地进行了放射治疗，平均每个分次进行 10.06±2.74 次屏气。
mDIBH 是一种有效的方法，可以有效地降低需要 IMLN-RT 的心脏解剖结构不良患者的平均心脏剂量，从而简化他们的计划和治疗。平均心脏剂量的降低与最大心脏距离的降低成正比。
