Impact of dental implants on dose calculation accuracy: A comparison of Acuros XB and Anisotropic analytical algorithm in head and neck radiotherapy

Abstract

Purpose: To compare the dosimetric performance of the Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) dose calculation algorithms in head and neck cancer patients with metallic dental implants undergoing VMAT radiotherapy.

Methods: A retrospective dosimetric study was conducted on fifteen head and neck squamous cell carcinoma patients with metallic denture implants. For each patient, two VMAT plans were generated in Eclipse Treatment Planning System using identical beam arrangements and optimization objectives, with dose calculations performed separately using AAA and AXB algorithms. Dosimetric parameters including PTV maximum dose, minimum dose, D95%, and doses to organs at risk (brainstem, spinal cord, optic chiasm, and parotid glands) were evaluated and compared. Statistical analysis was performed using SPSS with a significance level of p < 0.05.

Results: AXB demonstrated higher PTV maximum dose estimates (110.0% vs 108.56%) and lower PTV minimum dose estimates (77.25% vs 81.27%) compared with AAA. PTV D95% was slightly lower with AXB (96.37% vs 97.50%), suggesting a more conservative assessment of target coverage. For organs at risk, AXB predicted higher doses to the optic chiasm (26.47 Gy vs 24.46 Gy), brainstem (35.87 Gy vs 33.39 Gy), spinal cord (34.70 Gy vs 31.59 Gy), and parotid glands (25.70 Gy vs 25.35 Gy). These findings indicate that AAA may underestimate dose in regions affected by metallic implants and tissue heterogeneities.

Conclusion: Acuros XB provides more realistic dose calculations in the presence of metallic dental implants by accurately accounting for tissue heterogeneity and high-density materials. Its improved modelling capability may enhance treatment plan evaluation and support safer dose delivery in head and neck radiotherapy