S2361
Physics - Quality assurance and auditing
ESTRO 2026
Digital Poster 2348
Commissioning of a nonclinical six degree-of- freedom couch and integrated surface guidance imaging system on an O-ring linear accelerator Jufri Setianegara, Douglas Bollinger, Jack Shaw, Maksym Sharma, Brook Byrd, Steven Philbrook, Kevin Teo Department of Radiation Oncology, University of Pennsylvania, Philadelphia, USA Purpose/Objective: Current O-ring type linacs enable fast and streamlined patient radiotherapy treatments. However, the translational differences between the treatment and setup isocenters pose unique engineering challenges in designing a compatible 6DOF treatment couch. The purpose of this work is to commission and assess the achievable mechanical accuracies of a pre-clinical 6DOF couch for streamlined multi-isocenter treatments on an O-ring linac with integrated SGRT capabilities. Material/Methods: A new PerfectKinetix dynamic couch (Varian Medical Systems) with 6DOF capability was installed on a Halcyon V5 linac. Mechanical accuracy under individual ±4cm/3° translations/rotations was assessed with physical measurements. Radiation vs rotational isocenter accuracy was assessed with a scintillating imaging cone (XRV-124, Logos Systems International). Composite translations/rotations were performed with an anthropomorphic head phantom and their accuracy assessed with an integrated IDENTIFY V5.0 SGRT system (Varian Medical Systems) and radiographically with kV-CBCT. This phantom was displaced by nominal composite translations/rotations and the residual SGRT and CBCT shifts relative to nominal values recorded. These measurements were repeated at maximum 280 kg couch loading. The couch’s translation-under-rotation accuracy was assessed for multi-isocenter treatments with a 3D- printed 3° wedge phantom. Rotational corrections were first performed to level the 3° wedge and translations subsequently performed to displace the phantom between two nominal-spaced BBs along the wedge’s slope. Translation-under-rotation accuracy was assessed radiographically with CBCT with reference to BBs. Couch attenuation was performed by delivering 6FFF 10 × 10cm2 fields to a CC13 detector at isocenter at a depth of 5cm in solid water (reference) and through the solid water and couch.
Results: The couch was accurate to ±0.05cm/0.1° under individual translations/rotations. There is a maximum radiographic isocenter 3D deviation of 0.070cm under a 3° yaw rotation with an average 3D deviation of 0.05cm over all rotations. Under composite shifts, residual SGRT and CBCT deviations were within ≤ 0.1cm and ≤ 0.05cm of expected readings with and without load and thus, within the thermal noise floor and registration uncertainty of these systems. Vertical load deflection of the couch at maximum 280kg capacity was -0.45cm and fully-correctable. Patient- centric translations under rotational corrections were within ≤ 0.1cm which represented positional uncertainties in the BB placements. Couch attenuation to 6FFF beams had an average value of 1.904%.
Made with FlippingBook - Share PDF online