Dose- and LET-painting with particle therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Optimization

Background:

• Tumor hypoxia limits radiotherapy effectiveness.
• High-linear energy transfer (LET) radiation, like carbon ions, has potential benefits but its distribution is challenging.
• Spread-out Bragg peaks (SOBP) can dilute LET in the target volume.

Purpose of the Study:

• To investigate treatment plan optimization for redistributing LET to maximize it within the tumor volume.
• To explore strategies for overcoming tumor hypoxia using tailored LET distributions.
• To assess the potential of combining dose and LET optimization for improved radiotherapy outcomes.

Main Methods:

• Treatment plan optimization using carbon ion beams to shape LET distributions.
• Investigating multi-modal treatment planning combining carbon ions with protons and/or photons.
• Analyzing the relationship between hypoxia, LET, and the oxygen enhancement ratio (OER).

Main Results:

• LET distributions can be significantly shaped by treatment planning, independent of absorbed dose or biological effective dose.
• Multi-modal approaches allow for precise "LET boosts" within the target volume.
• High-LET radiation can be strategically confined to hypoxic tumor regions.

Conclusions:

• Optimized LET distribution can overcome tumor hypoxia and enhance radiotherapy efficacy.
• Targeting high-LET radiation to hypoxic tumor areas and low-LET to normoxic tissues offers therapeutic advantage.
• Simultaneous dose and LET optimization holds promise for improving tumor control and reducing normal tissue complication probability (NTCP).