⁴He dose- and track-averaged linear energy transfer: Monte Carlo algorithms and experimental verification

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Physics

Background:

• Hadrontherapy is exploring new ion species beyond protons and carbon for advanced radiotherapy.
• Multi-ion treatments offer potential for personalized radiation delivery based on tumor characteristics.
• Helium-4 (⁴He) ions are a promising alternative for specific therapeutic applications.

Purpose of the Study:

• To extend the understanding and calculation of biological-relevant quantities for ⁴He ions in hadrontherapy.
• To validate Geant4 Monte Carlo algorithms for dose- and track-averaged Linear Energy Transfer (LET) calculations with ⁴He ions.
• To compare simulated LET values with experimental microdosimetric measurements.

Main Methods:

• Utilized Geant4 Monte Carlo simulations to calculate dose- and track-averaged LET for ⁴He ions.
• Validated algorithms for mixed fields including secondary ions from target and projectile fragmentation.
• Conducted experimental microdosimetry using MicroPlus probe and nano-TEPC at INFN-LNS.
• Compared simulated LET (L¯dTotal, L¯tTotal) with experimental lineal energy means (y¯D, y¯T).

Main Results:

• Demonstrated good agreement between simulated and experimentally measured LET values (L¯dTotal, L¯tTotal vs. y¯D, y¯T).
• Validation was successful for both full energy and modulated ⁴He ion beams.
• Microdosimetric measurements were performed using two distinct detectors, MicroPlus and nano-TEPC.

Conclusions:

• The Monte Carlo approach is a highly effective tool for precise LET calculation in hadrontherapy.
• This validated method accurately simulates nuclear interactions, even in complex clinical scenarios.
• The findings support the use of ⁴He ions and advanced simulation techniques in future radiotherapy.