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Abstract：
BACKGROUND: Dose to heart substructures is a better predictor for major adverse cardiac events (MACE) than mean heart dose (MHD). We propose an avoidance planning strategy for important cardiac substructures.
METHODS: Two plans, clinical and cardiac substructure-avoidance plan, were generated for twenty patients. Five dose-sensitive substructures, including left ventricle, pulmonary artery, left anterior descending branch, left circumflex branch and the coronary artery were chosen. The avoidance plan aims to meet the target criteria and organ-at-risk (OARs) constraints while minimizing the dose parameters of the above five substructures. The dosimetric assessments included the mean dose and the maximum dose of cardiac substructures and several volume parameters. In addition, we also evaluated the relative risk of coronary artery disease (CAD), chronic heart failure (CHF), and radiation pneumonia (RP).
RESULTS: Pearson correlation coefficient and R2 value of linear regression fitting demonstrated that MHD had poor prediction ability for the mean dose of the cardiac substructures. Compared to clinical plans, an avoidance plan is able to statistically significantly decrease the dose to key substructures. Meanwhile, the dose to OARs and the coverage of the target are comparable in the two plans. In addition, it can be observed that the avoidance plan statistically decreases the relative risks of CAD, CHF, and RP.
CONCLUSIONS: The substructure-avoidance planning strategy that incorporates the cardiac substructures into optimization process, can protect the important heart substructures, such as left ventricle, left anterior descending branch and pulmonary artery, achieving the substantive sparing of dose-sensitive cardiac structures, and have the potential to decrease the relative risks of CAD, CHF, and RP.
METHODS: Two plans, clinical and cardiac substructure-avoidance plan, were generated for twenty patients. Five dose-sensitive substructures, including left ventricle, pulmonary artery, left anterior descending branch, left circumflex branch and the coronary artery were chosen. The avoidance plan aims to meet the target criteria and organ-at-risk (OARs) constraints while minimizing the dose parameters of the above five substructures. The dosimetric assessments included the mean dose and the maximum dose of cardiac substructures and several volume parameters. In addition, we also evaluated the relative risk of coronary artery disease (CAD), chronic heart failure (CHF), and radiation pneumonia (RP).
RESULTS: Pearson correlation coefficient and R2 value of linear regression fitting demonstrated that MHD had poor prediction ability for the mean dose of the cardiac substructures. Compared to clinical plans, an avoidance plan is able to statistically significantly decrease the dose to key substructures. Meanwhile, the dose to OARs and the coverage of the target are comparable in the two plans. In addition, it can be observed that the avoidance plan statistically decreases the relative risks of CAD, CHF, and RP.
CONCLUSIONS: The substructure-avoidance planning strategy that incorporates the cardiac substructures into optimization process, can protect the important heart substructures, such as left ventricle, left anterior descending branch and pulmonary artery, achieving the substantive sparing of dose-sensitive cardiac structures, and have the potential to decrease the relative risks of CAD, CHF, and RP.
摘要：
背景：心脏亚结构剂量比平均心脏剂量（MHD）更好地预测主要不良心脏事件（MACE）。我们提出了一种针对重要心脏子结构的回避计划策略。
方法：两个计划，临床和心脏子结构回避计划，为20名患者生成。五个剂量敏感的亚结构,包括左心室,肺动脉,左前降支,选择左回旋支和冠状动脉。避免计划旨在满足目标标准和危险器官（OAR）约束，同时最小化上述五个子结构的剂量参数。剂量学评估包括心脏亚结构的平均剂量和最大剂量以及几个体积参数。此外,我们还评估了冠状动脉疾病（CAD）的相对风险，慢性心力衰竭（CHF），和放射性肺炎（RP）。
结果：线性回归拟合的Pearson相关系数和R2值表明，MHD对心脏子结构的平均剂量预测能力较差。与临床计划相比，回避计划能够在统计学上显着降低关键子结构的剂量。同时,在两种计划中，OAR的剂量和靶标的覆盖率具有可比性。此外,可以观察到，回避计划在统计上降低了CAD的相对风险，CHF,和RP。
结论：将心脏子结构纳入优化过程的子结构回避计划策略，可以保护重要的心脏亚结构，比如左心室，左前降支和肺动脉,实现对剂量敏感的心脏结构的实质性保留，并有可能降低CAD的相对风险，CHF,和RP。
方法：两个计划，临床和心脏子结构回避计划，为20名患者生成。五个剂量敏感的亚结构,包括左心室,肺动脉,左前降支,选择左回旋支和冠状动脉。避免计划旨在满足目标标准和危险器官（OAR）约束，同时最小化上述五个子结构的剂量参数。剂量学评估包括心脏亚结构的平均剂量和最大剂量以及几个体积参数。此外,我们还评估了冠状动脉疾病（CAD）的相对风险，慢性心力衰竭（CHF），和放射性肺炎（RP）。
结果：线性回归拟合的Pearson相关系数和R2值表明，MHD对心脏子结构的平均剂量预测能力较差。与临床计划相比，回避计划能够在统计学上显着降低关键子结构的剂量。同时,在两种计划中，OAR的剂量和靶标的覆盖率具有可比性。此外,可以观察到，回避计划在统计上降低了CAD的相对风险，CHF,和RP。
结论：将心脏子结构纳入优化过程的子结构回避计划策略，可以保护重要的心脏亚结构，比如左心室，左前降支和肺动脉,实现对剂量敏感的心脏结构的实质性保留，并有可能降低CAD的相对风险，CHF,和RP。
