The accuracy of Eclipse AXB and AAA dose algorithms with dental amalgam

Area of Science:

• Medical Physics
• Radiotherapy
• Dental Materials

Background:

• Dental restorations, particularly high-density materials like amalgam, present challenges in CT imaging and radiation dose calculation.
• Existing treatment planning systems (TPS) show limitations in accurately predicting dose downstream of such materials.

Purpose of the Study:

• To evaluate the accuracy of dose calculation algorithms (Acuros XB and Anisotropic Analytical Algorithm) for dental amalgam restorations.
• To investigate the impact of overriding CT density values on dose prediction accuracy.

Main Methods:

• Dental amalgam was placed in a solid water phantom, and dose measurements were taken at various depths.
• Eclipse TPS was used to calculate doses, comparing film measurements with different override settings for amalgam.
• Both Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) were assessed.

Main Results:

• AXB showed poor agreement for depth dose downstream of amalgam, irrespective of override material.
• Applying known mass density with AAA yielded good agreement (1.8% and 2.8% for 6 MV and 10 MV beams).
• Overriding with stainless steel in AXB provided the closest agreement (1.1% and 1.8% above measured dose for 6 MV and 10 MV).

Conclusions:

• Accurate CT density overrides are essential for reliable dose calculations in the presence of dental amalgam.
• The Anisotropic Analytical Algorithm (AAA) with applied mass density demonstrated superior accuracy compared to Acuros XB (AXB) for this specific scenario.
• Further research into optimizing algorithms for high-density materials in radiotherapy is warranted.