Linear Energy Transfer Incorporated Spot-Scanning Proton Arc Therapy Optimization: A Feasibility Study
Xiaoqiang Li, Xuanfeng Ding, Weili Zheng, Gang Liu, Guillaume Janssens, Kevin Souris, Ana María Barragán Montero, Di Yan, Craig Stevens, Peyman Kabolizadeh
Abstract
Purpose To integrate dose-averaged linear energy transfer (LET d ) into spot-scanning proton arc therapy (SPArc) optimization and to explore its feasibility and potential clinical benefits. Methods An open-source proton planning platform (OpenREGGUI) has been modified to incorporate LET d into optimization for both SPArc and multi-beam intensity-modulated proton therapy (IMPT) treatment planning. SPArc and multi-beam IMPT plans with different beam configurations for a prostate patient were generated to investigate the feasibility of LET d -based optimization using SPArc in terms of spatial LET d distribution and plan delivery efficiency. One liver and one brain case were studied to further evaluate the advantages of SPArc over multi-beam IMPT. Results With similar dose distributions, the efficacy of spatially optimizing LET d distributions improves with increasing number of beams. Compared with multi-beam IMPT plans, SPArc plans show substantial improvement in LET d distributions while maintaining similar delivery efficiency. Specifically, for the liver case, the average LET d in the GTV was increased by 124% for the SPArc plan, and only 9.6% for the 2-beam IMPT plan compared with the 2-beam non-LET d optimized IMPT plan. In case of LET optimization for the brain case, the SPArc plan could effectively increase the average LET d in the CTV and decrease the values in the critical structures while smaller improvement was observed in 3-beam IMPT plans. Conclusion This work demonstrates the feasibility and significant advantages of using SPArc for LET d -based optimization, which could maximize the LET d distribution wherever is desired inside the target and averts the high LET d away from the adjacent critical organs-at-risk.