Department of Radiation Oncology, New York University Langone Perlmutter Cancer Center, New York, New York.
Department of Radiation Oncology, New York University Langone Perlmutter Cancer Center, New York, New York.
Pract Radiat Oncol. 2020 Sep-Oct;10(5):330-338. doi: 10.1016/j.prro.2020.01.001. Epub 2020 Feb 1.
To compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters.
Patients with left breast ductal carcinoma in situ or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon signed-rank and rank-sum tests were used to compare intrapatient differences between plans for the entire cohort and within BV groups defined by tertiles.
Forty patients were enrolled. Thirty-four patients are included in the analysis owing to patient withdrawal or inability to hold breath. With WBI dose of 4005 to 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH and 77 cGy in P-FB (P = .08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH and 45 cGy in P-FB (P < .0001). Mean and max left anterior descending artery doses were 251 cGy and 551 cGy in S-DIBH, respectively (P = .1), and 324 cGy and 993 cGy in P-FB, respectively (P = .3). Hot spot and separation were 109% and 22 cm in S-DIBH, respectively, and 107% and 16 cm in P-FB, respectively (P < .0001). For patients with smallest BV, S-DIBH improved MHD and left anterior descending artery doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (P = .05), and max (P = .03) and mean (P = .02) left anterior descending artery doses, and the reduction in MLD, hot spot, and separation with P-FB increased (P < .05).
MHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.
比较使用深吸气屏气（S-DIBH）仰卧位和自由呼吸（P-FB）俯卧位生成的辅助全乳照射（WBI）放疗计划的心肺剂量，并研究乳房体积（BV）对剂量学参数的影响。
本研究为单中心前瞻性研究，纳入了接受辅助 WBI 的左乳腺癌导管原位癌或浸润性癌患者。患者接受 S-DIBH 和 P-FB 模拟；使用两种扫描方法生成计划。对整个队列和按三分位数定义的 BV 组内的计划，采用 Wilcoxon 符号秩和检验和秩和检验进行比较。
共纳入 40 例患者。由于患者退出或无法屏气，34 例患者纳入分析。当 WBI 剂量为 4005 至 4256 cGy 时，S-DIBH 组的平均心脏剂量（MHD）为 80 cGy，P-FB 组为 77 cGy（P =.08）。S-DIBH 组的同侧肺平均剂量（MLD）为 453 cGy，P-FB 组为 45 cGy（P <.0001）。S-DIBH 组的左前降支平均剂量和最大剂量分别为 251 cGy 和 551 cGy（P =.1），P-FB 组分别为 324 cGy 和 993 cGy（P =.3）。S-DIBH 组的热点和分离分别为 109%和 22 cm，P-FB 组分别为 107%和 16 cm（P <.0001）。对于 BV 最小的患者，S-DIBH 改善了 MHD 和左前降支剂量；对于 BV 最大的患者，P-FB 改善了心脏剂量学。随着 BV 的增加，P-FB 对 MHD（P =.05）、最大（P =.03）和平均（P =.02）左前降支剂量的优势增加，而 MLD、热点和分离的降低也增加（P <.05）。
P-FB 和 S-DIBH 之间的 MHD 没有差异，而 P-FB 的 MLD 显著更低。根据乳房体积进行分析显示，对于 BV 最小的女性，S-DIBH 改善了心脏剂量学，对于 BV 较大的女性，P-FB 改善了心脏剂量学，从而为使用乳房大小来帮助确定 WBI 的最佳定位提供了剂量学依据。
