Ionization Detail Parameters for DNA Damage Evaluation in Charged Particle Radiotherapy: Simulation Study Based on...

Area of Science:

• Physics and Biology Interface
• Radiation Science
• Nanotechnology

Background:

• Understanding biological effects of charged particles requires detailed ionization information.
• Nanodosimetry offers novel quantities to characterize particle track structure.
• This can enhance charged particle radiotherapy planning by incorporating ionization details.

Purpose of the Study:

• To analyze ionization cluster size distributions in nanometer volumes using Monte Carlo simulations.
• To propose a novel nanodosimetric parameter (R2) for evaluating radiation quality based on biological consequences.
• To correlate R2 with radiobiological data and predict treatment outcomes.

Main Methods:

• Utilized Monte Carlo simulations with Geant4-DNA code for diverse charged particles.
• Analyzed ionization cluster size distributions within nanometer-scale volumes.
• Correlated simulation results with biological parameters from the PIDE database (V79 cell line).

Main Results:

• Developed a novel parameter R2 based on ionization cluster size distributions.
• R2 incorporates the probability of sub-lethal damage, addressing limitations of existing parameters (Fk).
• Demonstrated strong correlation between R2 and radiobiological data (inactivation cross-section).

Conclusions:

• The novel nanodosimetric parameter R2 effectively evaluates radiation quality in terms of biological effects.
• R2 provides a foundation for improved prediction of biological outcomes in radiotherapy.
• This approach enhances the precision of charged particle radiotherapy planning.