Interinstitutional experience in verification of external photon dose calculations

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• Accurate dose calculation is crucial for effective external photon therapy.
• Pixel-based algorithms are widely used in treatment planning systems.
• Independent verification of these algorithms is essential for patient safety.

Purpose of the Study:

• To evaluate the accuracy of pixel-based dose calculation algorithms used by four institutions.
• To compare computational results with phantom measurements of increasing complexity.
• To identify discrepancies and areas for improvement in dose calculation methods.

Main Methods:

• Utilized ionization chambers and thermoluminescent dosimeters for phantom measurements.
• Tested algorithms with various field configurations, including wedged and blocked fields.
• Assessed treatment planning systems using anthropomorphic phantoms with CT data.

Main Results:

• Demonstrated good overall agreement between calculated and measured doses for all tested algorithms.
• Identified specific regions where discrepancies between calculation and measurement occurred.
• Highlighted the impact of surface curvature and tissue heterogeneity on dose accuracy.

Conclusions:

• Pixel-based dose calculation algorithms generally provide accurate results for external photon therapy.
• Further algorithm refinement is needed to address discrepancies in complex scenarios.
• Ensuring algorithm accuracy is vital for optimizing radiation treatment planning and clinical outcomes.