Calorimetric determination of the absorbed dose‐to‐water beam quality correction factor kQfor high‐energy photon beams

A method has been developed for measuring photon beam quality correction factors kQusing direct transfer with a water calorimeter. kQvalues were measured for beam qualities varying between 6 and 23 MV for a Capintec PR‐06 and a PTW W30001 cylindrical ionization chamber. Measured values were intercompared with published sets of computed kQvalues and agreement was found to be within measurement uncertainty (1%, one standard deviation).