The accuracy of the Acuros XB algorithm in external beam radiotherapy – a comprehensive review

The accuracy of dose calculation algorithms has been a topic of interest among the radiotherapy community throughout last decades. On one hand the advancements in computers and algorithms has improved the accuracy, but on the other hand the developments in other parts of treatment process, in treatment delivery techniques and in treatment devices have always pushed the requirements to the next level. In this review article a comprehensive overview on the accuracy of a new type ‘c’ dose calculation algorithm, the Acuros XB (AXB) algorithm (Varian Medical Systems, Inc., Palo Alto, CA, USA), is provided. All the articles that have applied the AXB algorithm in terms of external beam radiotherapy are included and the research frames with reported deviations to reference methods are described. For the homogeneous water phantoms the reported accuracy was from 1% to 2%, being of similar level for heterogeneous phantoms, in rare occasions lower. In anthropometric and anthropomorphic phantoms the mean deviations were about 2% and slightly larger for single points and/or small regions. With patient plans the reported average discrepancies were less than from 3% to 5%. Almost without exceptions, the algorithm has proven to perform better than other existing commercial dose calculation algorithms. The number of such papers, in which the AXB algorithm is the only dose determination method, is already notable, which indicates that the accuracy of the algorithm is trusted for reference use and it also, with reported dosimetric results, implies that the AXB algorithm has reached its maturity.