Considerations for shoot-through FLASH proton therapy.

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Conventional proton radiotherapy faces challenges including Bragg peak positioning uncertainties, in vivo dose verification difficulties, and complex relative biological effectiveness (RBE) considerations.
• The advent of FLASH proton radiotherapy presents an opportunity to address these limitations through novel treatment delivery techniques.

Purpose of the Study:

• To investigate the feasibility and potential benefits of a shoot-through FLASH proton radiotherapy technique.
• To evaluate its impact on dose distribution, normal tissue sparing, and treatment uncertainties in a case study.

Main Methods:

• A preliminary treatment plan for a neurological tumor was developed using a shoot-through FLASH proton therapy approach.
• The plan was evaluated for its ability to meet organ at risk (OAR) dose constraints using a non-optimized treatment planning system.

Main Results:

• The shoot-through FLASH plan demonstrated significant effective dose reduction in healthy tissues.
• The technique eliminated uncertainties associated with Bragg peak positioning and the need for large treatment margins.
• Relative biological effectiveness (RBE) issues became less relevant due to the beam's high energy penetration.

Conclusions:

• Shoot-through FLASH proton radiotherapy is a promising modality that could mitigate current proton therapy uncertainties.
• Potential advantages include simplified planning, improved normal tissue sparing, and the possibility of portal dosimetry for treatment verification.
• Clinical trials for various cancers are feasible with current technology, though higher energies are needed for certain sites.