Mayo Clinic Florida, Department of Radiation Oncology, Jacksonville, Florida.
University of Florida Health Proton Therapy Institute, Jacksonville, Florida; Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida.
Pract Radiat Oncol. 2020 May-Jun;10(3):e147-e154. doi: 10.1016/j.prro.2019.09.015. Epub 2019 Oct 2.
Mean heart dose (MHD) correlates with late cardiac toxicity among survivors of lymphoma receiving involved-field radiation therapy (IFRT). We investigated MHD and cardiac substructure dose across older and newer radiation fields and techniques to understand the value of evaluating MHD alone.
After institutional review board approval, we developed a database of dosimetry plans for 40 patients with mediastinal lymphoma, which included IFRT (anterior-posterior and posterior-anterior), involved-site radiation therapy (ISRT) + 3-dimensional conformal radiation therapy (3DCRT), ISRT + intensity modulated radiation therapy, and ISRT + proton therapy plans for each patient. Each plan was evaluated for dose to the heart and cardiac substructures, including the right and left ventricles (RV, LV) and atria (RA, LA); tricuspid, mitral (MV), and aortic valves; and left anterior descending coronary artery (LAD). Correlation between MHD and cardiac substructure dose was assessed with linear regression. A correlation was considered very strong, strong, moderate, or weak if the r was ≥0.8, 0.6-0.79, 0.4-0.59, or <0.4, respectively.
A very strong correlation was observed between MHD and the mean cardiac substructure dose for each plan as follows: IFRT-LV, RV, LA, MV and LAD; ISRT + 3DCRT-LV, RV, MV, TV, and LA; ISRT + intensity modulated radiation therapy-LV and RV; ISRT + proton therapy-none. The following strong correlations were observed: IFRT-RA; ISRT + 3DCRT-LAD, RA, AV; ISRT + IMRT-LA, RA, LAD, AV, TV, and MV; ISRT + proton therapy-LV only.
In the management of mediastinal lymphoma, more conformal treatment techniques can lead to more heterogeneous dose distributions across the heart, which translate into weaker relationships between mean heart dose and mean cardiac substructure doses. Consequently, models for assessing the risk of cardiac toxicity after radiation therapy that rely on MHD can be misleading when using modern treatment fields and techniques. Contouring the cardiac substructures and evaluating their dose is important when using contemporary RT.
受照射野内放射治疗（IFRT）的淋巴瘤幸存者的平均心脏剂量（MHD）与晚期心脏毒性相关。我们研究了新旧放射野和技术的 MHD 和心脏亚结构剂量，以了解单独评估 MHD 的价值。
在机构审查委员会批准后，我们为 40 例纵隔淋巴瘤患者开发了一个剂量学计划数据库，其中包括 IFRT（前后和后前）、受累部位放射治疗（ISRT）+ 三维适形放射治疗（3DCRT）、ISRT+调强放射治疗和 ISRT+质子治疗计划。对每个计划进行心脏和心脏亚结构剂量评估，包括右心室（RV）、左心室（LV）和心房（RA、LA）；三尖瓣、二尖瓣（MV）和主动脉瓣；以及左前降支冠状动脉（LAD）。用线性回归评估 MHD 与心脏亚结构剂量之间的相关性。如果 r 值≥0.8、0.6-0.79、0.4-0.59 或<0.4，则分别认为相关性非常强、强、中等或弱。
观察到 MHD 与每个计划的平均心脏亚结构剂量之间存在非常强的相关性，如下所示：IFRT-LV、RV、LA、MV 和 LAD；ISRT+3DCRT-LV、RV、MV、TV 和 LA；ISRT+调强放射治疗-LV 和 RV；ISRT+质子治疗-无。观察到以下强相关性：IFRT-RA；ISRT+3DCRT-LAD、RA、AV；ISRT+IMRT-LA、RA、LAD、AV、TV 和 MV；ISRT+质子治疗-LV 仅。
在纵隔淋巴瘤的治疗中，更适形的治疗技术可导致心脏内的剂量分布更加不均匀，从而导致 MHD 与平均心脏亚结构剂量之间的关系减弱。因此，在使用现代治疗野和技术时，依赖 MHD 评估放射治疗后心脏毒性风险的模型可能会产生误导。在使用当代 RT 时，勾画心脏亚结构并评估其剂量非常重要。
