Beam energy metrics for the acceptance and quality assurance of Halcyon linear accelerator

Purpose Establish and compare two metrics for monitoring beam energy changes in the Halcyon platform evaluate accuracy of these across multiple linacs. Method The first metric is derived from diagonal normalized flatness (FDN), which defined as ratio average measurements at a fixed off-axis equal distance along open profiles diagonals to measurement central axis with an ionization chamber array (ICA). second comes area (AR) quad wedge (QW) measured QW on top ICA. Beam changed by adjusting magnetron current non-clinical Halcyon. With D10cm water each energy, relationships between FDN or AR established linear regression six settings. coefficients regressions allow D10cm(FDN) calculation using D10cm(QW) profiles. Results Five linacs five institutions were used comparing values computed treatment planning system (TPS) water. For linacs, reported ICA based agreed that calculated TPS within –0.29 ± 0.23% 0.61% maximum discrepancy; –0.82 1.27% –2.43% discrepancy. Conclusion FDN-based can be acceptance testing also verification periodic quality assurance (QA) processes.