Fraction optimization for hybrid proton-photon treatment planning

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Hybrid proton-photon radiotherapy offers improved plan quality over single-modality approaches.
• Key benefits include enhanced robustness of target coverage and superior sparing of organs-at-risk (OAR).

Purpose of the Study:

• Develop a hybrid treatment planning method for optimizing proton and photon fractions.
• Enable clinical delivery of hybrid plans using either proton or photon machines day-to-day.
• Optimize both proton and photon plan variables for hybrid radiotherapy.

Main Methods:

• Jointly optimize proton spots and photon fluences for robust target coverage and OAR sparing.
• Enforce target dose uniformity individually for proton and photon dose components.
• Explicitly model and optimize the number of proton and photon fractions for plan quality.

Main Results:

• Hybrid plans demonstrated superior overall plan quality and OAR sparing compared to proton-only or photon-only plans.
• Achieved better target dose uniformity and robustness than proton-only plans across all tested cases.
• Showcased improved target coverage for head-and-neck (HN) and brain cases compared to photon-only plans.

Conclusions:

• A novel hybrid treatment planning method has been developed, optimizing fraction numbers and plan variables.
• Generated hybrid plans are suitable for separate and robust delivery on proton or photon machines.
• Preliminary findings indicate enhanced plan quality for hybrid plans over single-modality approaches.