Dosimetric comparison of Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) using Volumetric Modulated Arc Therapy (VMAT) for oesophageal cancer

Abstract

Author(s): S. Sriram Prasath, Akib Ahamed, Kiran Joshi, Satyam Arora, A. Prasheedha, Aranya Sarkar, Smita Jagdish Kalita, B. Arun, Moses ArunSingh, Tapesh Bhattacharya, Indranil Mallick, P. Ramesh Babu

Aim: To compare and analyse the dosimetric parameters between Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) algorithm in Volumetric Modulated Arc Therapy (VMAT) plans for Oesophageal Cancer.

Materials and Methods: Total 30 patients who were treated between the year 2020 and 2024 in our institute taken for this retrospective study. All the patients underwent VMAT treatments with dual Arc using AAA calculation and these patients dose plans were calculated using AXB using the same optimization parameters. The prescription doses to the target were ranging between 41.4 Gy to 60 Gy. The dosimetric comparison between AAA and AXB was performed using Planning Target Volume (PTV) coverage, Conformity Index (CI), Homogeneity Index (HI) and organ at risk (OAR) doses such as spinal cord planning risk volume, dose received by total lung volume of 20 Gy, 10 Gy, and 5 Gy (V20, V10, V5) and mean dose to heart. The statistical analysis was done using paired sample t-test.

Results: The mean difference in CI and HI were 0.64 (p<0.001) and 0.10 (p=0.10 respectively. The mean dose differences between these 2 calculation algorithms were insignificant for Spinal cord PRV (MD=0.92 Gy, p=0.62), heart mean dose (0.27 Gy (p=0.90)) and total lung doses. The mean difference for total lung was 0.16 Gy (p=0.81), and in V20Gy, V10Gy V5Gy were 0.16% (p=0.93), 0.58% (p= 0.81), 1.19% (p=0.74) respectively.

Conclusion: We observed from the results that the difference in HI, OAR doses were insignificant, but difference in the CI showed significant between AAA and AXB calculated VMAT plans. AAA overestimates the coverage in PTV when compared to AXB. This suggests that appropriate calculation algorithm to be chosen for sites having much heterogeneity in tissues surrounding the PTV.

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