Interface effects in the Monte Carlo simulation of electron tracks

Area of Science:

• Medical Physics
• Computational Physics
• Radiation Dosimetry

Background:

• Monte Carlo methods are crucial for simulating electron transport in various media.
• Accurate energy deposition modeling is essential for radiation therapy and diagnostics.
• Existing models may introduce errors at interfaces between materials of different densities.

Purpose of the Study:

• To investigate an error in Monte Carlo electron transport simulations at material interfaces.
• To analyze the impact of this error on energy deposition calculations.
• To develop and present a corrected algorithm for interface crossing.

Main Methods:

• Analog of Fano's theorem applied to stepwise electron path representation.
• Analysis of electron path distribution and energy deposition.
• Development of a new interface-crossing algorithm.

Main Results:

• An error in electron path distribution and energy deposition was identified.
• The error magnitude depends on cavity shape and size relative to electron path length.
• A typical calculation showed a 3% energy deficit in the cavity with a 10% step size.

Conclusions:

• The stepwise representation of electron paths in Monte Carlo simulations can lead to interface errors.
• A novel algorithm for crossing density interfaces eliminates this error.
• Accurate electron transport modeling is improved by addressing interface phenomena.