Energy-loss straggling algorithms for Monte Carlo electron transport

Area of Science:

• Computational Physics
• Medical Physics
• Radiation Transport

Background:

• Electron energy-loss straggling is crucial for accurate Monte Carlo transport simulations.
• Existing methods may lack efficiency or accuracy in modeling straggling, especially at low energies or with binding effects.

Purpose of the Study:

• To develop and validate a new method for modeling electron and positron energy-loss straggling in Monte Carlo simulations.
• To improve the speed and accuracy of electron transport simulations, particularly for energy spectrum calculations.

Main Methods:

• Calculated Vavilov energy-loss distributions using Møller and Bhabha cross-sections.
• Developed new algorithms based on the first three moments of the energy-loss distribution for rapid sampling.
• Incorporated these algorithms into the GEPTS(III) Monte Carlo code, simulating soft collisions separately.

Main Results:

• GEPTS(III) demonstrated significant speed gains (up to 5-11 times faster than EGSnrc) for electron transport simulations.
• The new method accurately accounts for energy-spectrum broadening due to binding effects, unlike EGSnrc.
• Electron dose distributions in water were less sensitive to straggling, but energy spectra calculations showed high sensitivity.

Conclusions:

• GEPTS(III) offers substantial advantages in speed and accuracy for electron transport simulations, especially for energy spectrum calculations.
• The new approach is suitable for accurate electron cross-section data at low energies.
• The method shows promise for clinical electron beam modeling studies.