A pencil beam algorithm for proton dose calculations

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• Proton therapy offers superior dose conformity due to sharp lateral penumbra and rapid dose fall-off.
• Accurate modeling of beam-modifying devices and air gaps is critical for realizing these benefits.
• Existing algorithms may not fully account for upstream material and air gap effects.

Purpose of the Study:

• To develop and validate a novel pencil beam algorithm for proton dose calculations.
• To accurately incorporate the influence of upstream beam modifiers and air gaps.
• To improve the modeling of proton beam penumbra and dose distribution.

Main Methods:

• Developed a pencil beam algorithm incorporating upstream materials and air gap effects.
• Introduced a new method for selecting pencil beam locations to improve penumbra modeling.
• Created a faster broad-beam version of the algorithm for practical applications.
• Validated the algorithm using experimental data from a large-field proton beam.

Main Results:

• The algorithm accurately accounts for upstream materials and air gaps in proton dose calculations.
• The new pencil beam placement strategy improves penumbra accuracy.
• Experimental validation showed good agreement between the algorithm's predictions and measured data.
• The broad-beam version provides reasonably accurate penumbra calculations.

Conclusions:

• The developed algorithm enhances the accuracy of proton dose calculations, particularly concerning upstream effects.
• This improved modeling can lead to more precise radiation delivery in proton therapy.
• The findings support the use of this algorithm for optimizing treatment planning and delivery.