Multi-IMPT: a biologically equivalent approach to proton ARC therapy.

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Proton spot-scanning arc therapy (ARC) offers improved target dose conformity over standard intensity-modulated proton therapy (IMPT).
• Efficient ARC delivery is hindered by frequent energy changes during continuous gantry rotation.
• This study introduces a method to achieve ARC-equivalent plan quality using multiple IMPT (multi-IMPT) plans.

Purpose of the Study:

• To propose and evaluate a novel multi-IMPT method for delivering biologically effective dose (BED) equivalent to ARC.
• To compare the plan quality of the proposed multi-IMPT approach with conventional ARC therapy.

Main Methods:

• The multi-IMPT method uses distinct subsets of beam angles per fraction.
• Biologically effective dose (BED) for organs at risk (OAR) and physical dose for targets are optimized per fraction.
• Inverse optimization was performed using iterative convex relaxation and alternating direction method of multipliers.

Main Results:

• Multi-IMPT demonstrated comparable plan quality to ARC across various clinical cases.
• The multi-IMPT approach showed improved OAR sparing and target dose coverage in a prostate cancer example.
• Dose distributions were similar for lung cancer, slightly inferior for brain cases, and showed better coverage with slightly higher OAR BED for head-and-neck cases.

Conclusions:

• A multi-IMPT approach can effectively deliver ARC-equivalent plan quality.
• This method presents a promising strategy for overcoming the delivery challenges of ARC therapy.
• The proposed technique may enhance treatment efficiency and therapeutic outcomes in proton therapy.