Optimization of pencil beam widths for electron-beam dose calculations

Area of Science:

• Medical Physics
• Radiotherapy Physics
• Computational Dosimetry

Background:

• Pencil beam algorithms are widely used for electron-beam radiotherapy dose calculations.
• Current methods inadequately model electron range straggling, leading to inaccuracies, particularly for arced beams.
• Existing models lack validation in heterogeneous patient-like phantoms.

Purpose of the Study:

• To develop and validate a modified pencil beam algorithm that incorporates electron range straggling.
• To improve the accuracy of dose distribution calculations for both stationary and arced electron beams.
• To assess the model's performance in heterogeneous phantom environments.

Main Methods:

• A modified pencil beam algorithm incorporating range straggling was developed.
• The model was tested for stationary electron beams against measured isodose lines.
• Performance in heterogeneous slab phantoms was evaluated, focusing on pencil beam width prediction.

Main Results:

• The modified model accurately predicts isodose lines for stationary beams within 1 mm down to the 10% dose level.
• Pencil beam width predictions in heterogeneous phantoms were within 20% of measured values.
• The proposed method significantly reduces errors associated with range straggling in arced beam calculations.

Conclusions:

• Incorporating range straggling into electron pencil beam calculations is crucial for accurate dose distribution modeling.
• The presented model demonstrates improved accuracy for stationary and arced electron beams, even in heterogeneous tissues.
• This approach enhances the reliability of radiotherapy dose planning for cancer treatment.