A comparative analysis of Acuros XB and the analytical anisotropic algorithm for volumetric modulation arc therapy |
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| Authors: | Raju P. Srivastava K. Basta Werner De Gersem Carlos De Wagter |
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| Affiliation: | 1.Radiotherapy Association Meuse Picardie, Centre Hospitalier Mouscron, Mouscron, Belgium; 2.Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium; 3.Department of Radiation Oncology and Experimental Cancer Research, Ghent University, Belgium |
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| Abstract: | BackgroundThis study aimed to verify the dosimetric impact of Acuros XB (AXB) (AXB, Varian Medical Systems Palo Alto CA, USA), a two model-based algorithm, in comparison with Anisotropic Analytical Algorithm (AAA ) calculations for prostate, head and neck and lung cancer treatment by volumetric modulated arc therapy (VMAT ), without primary modification to AA. At present, the well-known and validated AA algorithm is clinically used in our department for VMAT treatments of different pathologies. AXB could replace it without extra measurements. The treatment result and accuracy of the dose delivered depend on the dose calculation algorithm.Materials and methodNinety-five complex VMAT plans for different pathologies were generated using the Eclipse version 15.0.4 treatment planning system (TPS). The dose distributions were calculated using AA and AXB (dose-to-water, AXBw and dose-to-medium, AXBm), with the same plan parameters for all VMAT plans. The dosimetric parameters were calculated for each planning target volume (PTV) and involved organs at risk (OA R). The patient specific quality assurance of all VMAT plans has been verified by Octavius®-4D phantom for different algorithms.ResultsThe relative differences among AA, AXBw and AXBm, with respect to prostate, head and neck were less than 1% for PTV D95%. However, PTV D95% calculated by AA tended to be overestimated, with a relative dose difference of 3.23% in the case of lung treatment. The absolute mean values of the relative differences were 1.1 ± 1.2% and 2.0 ± 1.2%, when comparing between AXBw and AA, AXBm and AA, respectively. The gamma pass rate was observed to exceed 97.4% and 99.4% for the measured and calculated doses in most cases of the volumetric 3D analysis for AA and AXBm, respectively.ConclusionThis study suggests that the dose calculated to medium using AXBm algorithm is better than AAA and it could be used clinically. Switching the dose calculation algorithm from AA to AXB does not require extra measurements. |
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| Keywords: | anisotropic analytical algorithm planning target volume volumetric modulated arc therapy multi-leaf collimator gamma index |
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