Synthetic computed tomography based dose calculation in prostate cancer patients with hip prostheses for magnetic resonance imaging-only radiotherapy

Background and PurposeMetallic hip prostheses cause substantial artefacts in both computed tomography (CT) magnetic resonance (MR) images used radiotherapy treatment planning (RTP) for prostate cancer patients. The aim of this study was to evaluate the dose calculation accuracy a synthetic CT (sCT) generation workflow improvement implant visibility using metal artefact reduction sequences.Materials MethodsThe included 23 patients with who had prostheses, which 10 bilateral implants. An in-house protocol applied create sCT comparison. compared volumes resulting avoidance sectors against target volume (PTV) uniformity organs at risk (OAR) sparing.ResultsMedian PTV difference between CT-based among all 0.1 % (-0.4 – 0.4%) (median(range)). Bladder rectum differences (V50Gy) were 0.2 (-0.3 1.1%) (-0.9 0.5%). median 3D local gamma pass rate partial arc cases Dixon MR sequence Γ20%2mm/2% = 99.9%. For full cases, reconstruction sequence, 99.0%.ConclusionsAn generating provided clinically feasible uni- remained <0.4%. Outphase enhanced smaller sectors, better OAR sparing, improved uniformity.