Advancing Proton FLASH Radiation Therapy: Innovations, Techniques, and Clinical Potentials

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Proton FLASH radiation therapy (RT) is an emerging technique.
• It aims to deliver conformal doses like intensity-modulated proton therapy (IMPT).
• It offers potential organ at risk (OARs) protection via the FLASH-sparing effect.

Purpose of the Study:

• To review recent advancements in proton FLASH-RT techniques.
• To discuss their advantages, limitations, and dosimetric comparisons.
• To explore their clinical utilization.

Main Methods:

• Review of transmission beams (TB), single-energy Bragg peak (SEBP), single-energy spread-out Bragg peak (SESOBP), hybrid FLASH, and multiple-energy spread-out Bragg peak (MESOBP).
• Analysis of dose conformity, OAR protection, and technical complexities.
• Comparison with IMPT and other FLASH techniques.

Main Results:

• TB FLASH-RT achieves conformity but has exit doses.
• SEBP and SESOBP improve OAR protection and conformity using range compensators/ridge filters.
• Hybrid FLASH and MESOBP FLASH offer advanced targeting and rapid energy switching.
• Only non-conformal TB FLASH-RT is currently used clinically for palliative RT.

Conclusions:

• Various proton FLASH-RT techniques show promise for improved treatment outcomes.
• Technical complexities and uncertainties regarding the FLASH effect limit widespread clinical adoption.
• Further research is needed to optimize and validate advanced FLASH-RT methods for diverse anatomical sites.