Radiation Oncology, P.D. Hinduja National Hospital, Mahim, Mumbai, Maharashtra, India.
J Cancer Res Ther. 2024 Jul 1;20(5):1539-1544. doi: 10.4103/jcrt.jcrt_2668_22. Epub 2024 Jan 22.
Deep inspiratory breath hold is one of the techniques for reducing the heart doses for left breast cancers. This study was conducted to confirm use of physical parameters from DIBH simulation CT scan like DIBH amplitude alongside several novel parameters to predict the heart dose reduction.
Segmentation and planning of radiation to the left breast on the free breathing (FB) and DIBH simulation scan was performed for 50 left-sided breast cancer patients treated with DIBH technique. Physical parameters, namely DIBH amplitude, anterior sternal displacement, diaphragmatic excursion, ratio of lung volume (cc) in DIBH scan to lung volume in FB scan (cc), and delta heart volume in field (DHVIF), were extracted and were compared with magnitude of heart dose reduction (mean heart dose, V30Gy, and D5%).
Forty-eight (96%) patients achieved reduction in the mean heart dose with DIBH technique, while all patients had reduction in V30Gy. The median reduction was 41%, 89.7%, and 63% in the mean dose, V30Gy, and D5%, respectively. While DIBH did not correlate with heart dose reduction, ratio of lung volumes and DHVIF showed a strong positive correlation with heart dose reduction (P < 0.05). Sternal displacement correlated weakly with heart dose reduction but strongly with DHVIF, demonstrating to be an indirect predictor.
Physical parameters like anterior sternal displacement, ratio of lung volumes of DIBH to FB, and possibly diaphragmatic movement can predict the dose reduction before the dose calculations by the physicist. These parameters can be used to construct a model to predict heart dose reduction.
深吸气屏气是降低左侧乳腺癌心脏剂量的技术之一。本研究旨在通过 DIBH 模拟 CT 扫描的物理参数（如 DIBH 幅度）以及其他几个新参数来确认其预测心脏剂量降低的作用。
对 50 例接受 DIBH 技术治疗的左侧乳腺癌患者进行了自由呼吸（FB）和 DIBH 模拟扫描的左乳房放射分割和计划。提取了物理参数，包括 DIBH 幅度、胸骨前位移、横膈膜移动、DIBH 扫描时肺容积（cc）与 FB 扫描时肺容积（cc）的比值（cc）以及场内心脏容积减少量（DHVIF），并与心脏剂量减少的幅度（平均心脏剂量、V30Gy 和 D5%）进行了比较。
48 例（96%）患者采用 DIBH 技术降低了平均心脏剂量，而所有患者均降低了 V30Gy。平均剂量、V30Gy 和 D5%的中位降低率分别为 41%、89.7%和 63%。DIBH 与心脏剂量降低无关，而肺容积比和 DHVIF 与心脏剂量降低呈强正相关（P < 0.05）。胸骨位移与心脏剂量降低弱相关，但与 DHVIF 强相关，表明其为间接预测指标。
物理参数如胸骨前位移、DIBH 与 FB 的肺容积比以及可能的横膈膜运动可以在物理学家进行剂量计算之前预测剂量降低。这些参数可用于构建预测心脏剂量降低的模型。
