Effect of tissue composition on dose distribution in electron beam radiotherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Biomedical Engineering

Background:

• Accurate dose distribution is critical in electron beam radiotherapy.
• Understanding tissue composition's impact on radiation dose is essential for treatment planning.
• Variations in tissue properties can potentially alter radiation delivery.

Purpose of the Study:

• To evaluate how different tissue compositions affect dose distribution during electron beam radiotherapy.
• To compare dose distributions in various soft tissues and tissue-equivalent materials.
• To determine the significance of these differences for clinical application.

Main Methods:

• Simulated a Siemens Primus linear accelerator and phantom using MCNPX Monte Carlo code.
• Investigated six soft tissues (muscle, adipose, blood, breast, 9-component, 4-component) and three tissue-equivalent materials (water, A-150 plastic, perspex).
• Calculated relative electron dose at various depths for 8, 12, and 14 MeV electron energies.

Main Results:

• Tabulated relative electron dose data for different materials and energies compared to 9-component soft tissue.
• Observed variations in dose distributions influenced by material composition, electron energy, and phantom depth.
• Concluded that observed differences were generally negligible due to Monte Carlo uncertainties.

Conclusions:

• Differences in dose distributions across various soft tissues and tissue-equivalent materials are not statistically significant.
• Further research with reduced uncertainties is recommended to explore material composition effects more precisely.
• Current electron beam radiotherapy planning may not require significant adjustments for common tissue variations.