Comparison of arc‐modulated cone beam therapy and helical tomotherapy for three different types of cancer

Purpose:Arc‐modulated cone beam therapy (AMCBT) is a fast treatment technique deliverable in a single rotation with a conventional C‐arm shaped linac. In this planning study, the authors assess the dosimetric properties of single‐arc therapy in comparison to helical tomotherapy for three different tumor types.Methods:Treatment plans for three patients with prostate carcinoma, three patients with anal cancer, and three patients with head and neck cancer were optimized for helical tomotherapy and AMCBT. The dosimetric comparison of the two techniques is based on physical quantities derived from dose‐volume histograms.Results:For prostate cancer, the quality of dose distributions calculated for AMCBT was of equal quality as that generated for tomotherapy with the additional benefits of a faster delivery and a lower integral dose. For highly complex geometries, the plan quality achievable with helical tomotherapy could not be achieved with arc‐modulated cone beam therapy.Conclusions:Rotation therapy with a conventional linac in a single arc is capable to deliver a high and homogeneous dose to the target and spare organs at risk. Advantages of this technique are a fast treatment time and a lower integral dose in comparison to helical tomotherapy. For highly complex cases, e.g., with several target regions, the dose shaping capabilities of AMCBT are inferior to those of tomotherapy. However, treatment plans for AMCBT were also clinically acceptable.