New Geant4-DNA physics model for electron track-structure simulations in gold nanoparticles.

Area of Science:

• Medical Physics
• Computational Physics
• Materials Science

Background:

• Accurate electron track-structure simulations are crucial for gold nanoparticle (AuNP)-aided radiotherapy.
• Current Geant4-DNA models have deficiencies in simulating electron interactions within AuNPs.
• Improving cross-section data is essential for precise dose enhancement calculations.

Purpose of the Study:

• Develop an improved Geant4-DNA physics model for electron track-structure simulations in AuNPs.
• Enhance accuracy over a broad energy range (10 eV to 1 MeV).
• Address limitations of the existing default model for AuNPs.

Main Methods:

• Developed a new energy-loss function for solid gold (Au) optimized with optical data.
• Calculated inelastic cross sections using the relativistic plane wave Born approximation (RPWBA).
• Incorporated low-energy corrections and a Landau damping approximation for plasmon decay.

Main Results:

• The new model shows excellent agreement (~2%) with NIST stopping power data, a significant improvement over the previous ~6%.
• Eliminated unphysical low-energy overestimations present in the default Geant4-DNA model.
• Achieved better agreement with advanced physics models for solid gold.

Conclusions:

• The developed model offers more accurate electron transport simulations within AuNPs.
• Enables better quantification of the secondary electron spectrum responsible for dose enhancement.
• Facilitates more precise calculations of radiobiological effects in AuNP-aided radiotherapy.