Linear Energy Transfer Incorporated Spot-Scanning Proton Arc Therapy Optimization: A Feasibility Study

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• Proton therapy offers precise dose delivery.
• Optimizing linear energy transfer (LET) distribution is crucial for maximizing therapeutic efficacy and minimizing toxicity.
• Spot-scanning proton arc therapy (SPArc) is an advanced technique with potential for improved treatment planning.

Purpose of the Study:

• To integrate dose-averaged linear energy transfer (LETd) into spot-scanning proton arc therapy (SPArc) optimization.
• To evaluate the feasibility and clinical benefits of LETd-based SPArc optimization.
• To compare SPArc with multi-beam intensity-modulated proton therapy (IMPT) for LETd optimization.

Main Methods:

• Modified an open-source proton planning platform (OpenREGGUI) to incorporate LETd into optimization for SPArc and multi-beam IMPT.
• Generated SPArc and multi-beam IMPT plans for prostate, liver, and brain cases.
• Investigated spatial LETd distribution and plan delivery efficiency.

Main Results:

• SPArc plans demonstrated substantial improvements in LETd distributions compared to multi-beam IMPT plans, with similar delivery efficiency.
• For a liver case, SPArc increased average LETd in the GTV by 124% compared to a non-LETd optimized IMPT plan.
• For a brain case, SPArc effectively increased LETd in the CTV and decreased it in critical structures.

Conclusions:

• SPArc-based LETd optimization is feasible and offers significant advantages over multi-beam IMPT.
• This technique allows precise control over LETd distribution within the target volume.
• SPArc can maximize therapeutic effects in the target while protecting surrounding critical organs.