A comparison between anisotropic analytical and multigrid superposition dose calculation algorithms in radiotherapy...

Area of Science:

• Medical Physics
• Radiotherapy
• Computational Biology

Background:

• Monte Carlo (MC) simulation offers the highest accuracy in radiotherapy dose calculations but is computationally intensive.
• Faster algorithms like Anisotropic Analytical Algorithm (AAA) and Multigrid Superposition (MGS) are commonly used in treatment planning systems.
• Evaluating dose calculation accuracy and efficiency of these algorithms is crucial for optimizing radiotherapy treatment.

Purpose of the Study:

• To compare the dose calculation accuracy of the Anisotropic Analytical Algorithm (AAA) and Multigrid Superposition (MGS) against Monte Carlo (MC) simulation.
• To assess the performance of AAA and MGS across different anatomical sites and tissue densities.
• To evaluate the computation time of AAA and MGS in clinical treatment planning.

Main Methods:

• Dose calculations were performed using AAA and MGS for brain, nasopharynx, lung, and prostate cancer patient CT data.
• Doses at various reference points (soft tissue, bone, air cavities, and their boundaries) were compared to MC simulations.
• Mean Absolute Percentage Error (MAPE) was used to quantify dose deviations, and computation times were recorded.

Main Results:

• Multigrid Superposition (MGS) demonstrated significantly lower Mean Absolute Percentage Errors (MAPEs) than Anisotropic Analytical Algorithm (AAA) across all cancer types and tissue density combinations (p<0.001).
• AAA showed dose deviations ranging from 1.8% to 4.9%, while MGS ranged from 1.6% to 2.9%.
• AAA had a significantly lower mean computation time compared to MGS (p<0.001), indicating faster plan calculation.

Conclusions:

• MGS offers superior dose calculation accuracy compared to AAA, particularly at tissue interfaces, but requires more computation time.
• Both AAA and MGS are clinically acceptable, with deviations generally below 4.0%, performing better in homogeneous tissues.
• The choice between AAA and MGS involves a trade-off between dose accuracy and computational efficiency in radiotherapy planning.