SU-E-T-529: Dosimetric Evaluation with Heterogeneity in Acuros XB Advanced Dose Calculation Algorithm and Anisotropic...

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Treatment Planning

Background:

• Accurate dose calculation is critical in radiotherapy.
• Air cavities (heterogeneities) in patients pose challenges for dose prediction algorithms.
• Comparing advanced algorithms is essential for improving treatment accuracy.

Purpose of the Study:

• To evaluate the accuracy of the Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) in predicting radiation doses beyond air gaps.
• To compare the performance of AXB and AAA against experimental measurements.

Main Methods:

• Created virtual phantoms with water-air-water layers in Eclipse Treatment Planning System.
• Computed central axis depth doses beyond simulated air gaps (2, 4, 6 cm) for 6MV photon beams.
• Manufactured physical phantoms and measured doses using an ionization chamber.
• Compared calculated doses (AXB, AAA) with measured doses.

Main Results:

• Acuros XB predicted doses within ±2% of measurements, with minor deviations in larger air gaps.
• Acuros XB demonstrated superior dose prediction accuracy compared to AAA across all depths.
• The smallest field size and largest air gap showed the greatest dose differences, particularly with AAA.

Conclusions:

• Acuros XB is more accurate for dose predictions in the presence of air cavities (heterogeneities).
• Findings support the use of Acuros XB for improved radiotherapy accuracy in complex patient anatomies.