SU‐E‐T‐261: Daily Quality Assurance for a 6D Robotic Couch System

Purpose: To create a daily quality assurance program that would evaluate the positioning accuracy and reproducibility of a new robotic couch system (CIVCO Medical Solutions) for routine clinical use. Methods: Translation accuracy and reproducibility were measured using a rectangular box phantom covered with 1.0 mm spaced graph paper. The couch was programmed to move a set of translations in all three directions. The magnitude and sign of the set translations alternated daily and encompassed the expected range of travel relevant to clinical use. The applied displacements ranged from 2.0 mm – 10.0 mm. An IGRT QA phantom (CIVCO Medical Solutions) was used for evaluating rotation accuracy and reproducibility. Digital levels on top of the phantom measured the rotations. The couch was programmed to move a set of pitch and roll rotations. The magnitude and sign of the set rotations alternated daily. The applied rotations ranged from 0.3 degrees – 1.5 degrees. A combination of translations and rotations were applied with the robotic couch and verified with CBCT. The CBCT was manually registered with a planning CT of the phantom and the shifts were recorded. Results: The maximum translational disagreement between the programmed and measured motions with the graph paper phantom was 0.5 mm. The maximum rotational disagreement between the programmed and measured motions that was identified by the digital levels mounted on the IGRT QA phantom was 0.2 degrees. The maximum deviations between the programmed and measured couch motions identified by CBCT were 2 mm for translations and 0.5 degrees for rotations. Conclusions: A daily quality assurance procedure, which evaluates daily positioning accuracy and reproducibility of a new, commercially available robotic couch, has been implemented. Based on the initial results, the system is accurate, reproducible, and safe for routine clinical use.