Four (4) Elekta Versa HD Linear accelerators at different sites within a network of 16 cancer centers were matched for the 6MV beam energy.
As part of commissioning IQM detectors at each of the 16 sites we investigated the agreement of IQM and waterphantom measurements among the four matched machines and implemented a universal beam model to calculate predicted IQM measurements for them.
Area output factors for field sizes from 1×1 cm2 to 30×30 cm2 and central axis beam profiles taken with water phantom and with IQM were compared among the four machines, then used to implement a universal beam model for use with IQM’s calculation algorithm to predict segment measurements.
Predicted segment signals were calculated for 20 complex VMAT Plans and then delivered at the 4 linear accelerators and compared.
The comparison between predicted and measured cumulative signals was evaluated based on (i) the average cumulative signal deviation, (ii) the standard deviation of cumulative signal deviations and (iii) the course of segment-specific standard deviations (SD) of cumulative signal deviations.
Due to the close agreement of machine QA and clinical plan results the team investigated whether the machine-specific, statistically-derived characterization of expected beam behavior would also yield uniform tolerance settings that could be applied for the matched machines.
Learn about all the exciting results of our beam matching verification study by downloading the white paper “Applicability of a universal calculation model for the IQM System at matched machines”. Simply click on the following link