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Dosimetric Performance of Orthogonal Dual-Layer Multi-Leaf Collimator System on Locally Advanced Lung Cancer: Cardiac
AiHui Feng1,2,3, YanHua Duan1,2,3, ZhangRu Yang1
1Department of Radiation Oncology, Shanghai Chest Hospital School of Medicine, Shanghai, China.
Purpose:
This study aims to reduce the risk of cardiovascular incidents and radiation pneumonia (RP) by improving the dose distribution to cardiac substructures through the use of a dual-layer multileaf collimator (MLC) accelerator- VenusX.
Methods And Materials:
Eighteen patients with advanced-stage lung cancer were selected for this study. The total lung, spinal cord, whole heart, and specific cardiac substructures (including the left ventricle [LV], pulmonary artery, left anterior descending artery, left circumflex artery [LCX], and coronary artery) were delineated as organs at risk and incorporated into the optimization process of the avoidance plan. Single-layer MLC plans optimized for the whole heart, referred to as S-WH plans (where WH denotes whole heart), were developed alongside single-layer MLC plans specifically designed to avoid cardiac substructures, known as S-CS plans (where CS denotes cardiac substructures). Additionally, dual-layer MLC avoidance plans, designated as D-CS plans, were created for each patient. We evaluated the relative risk of coronary artery disease, chronic heart failure, acute cardiac events, and RP, as well as the effective dose to the immune system.
Results:
D-CS plans significantly reduced the dose metrics of LV, pulmonary artery, left anterior descending artery, LCX, and the coronary, while maintaining target coverage and achieving comparable conformity index to the S-WH plans. Additionally, the D-CS plans significantly decreased the volume receiving 5 Gy (V5Gy) for the LV and V15Gy of LCX, with other substructures also experiencing a notable degree of dose reduction. Furthermore, the relative risk of coronary artery disease, chronic heart failure, acute cardiac event, and RP is ranked as follows: D-CS < S-CS < S-WH plans. Effective dose to the immune system of the D-CS plans indicated the lowest risk among the 3 plans.
Conclusions:
The dual-layer MLC system demonstrated superior performance compared to the single-layer MLC system in CS-avoidance plans, providing new opportunities for subsequent immunotherapy in patients with locally advanced lung cancer.
