Abstract
This report describes the update of the beam quality conversion factor KQ,Q0 of the standard dosimetry protocol in Japan. The KQ,Q0 corrects for the difference between the response of an ionization chamber in the reference beam quality Q0 used for calibrating the chamber and in the actual user beam quality Q. All changes of KQ,Q0 were caused by the perturbation correction factors which were recalculated by Monte Carlo simulation. With a calculation process, unsolved problems in this update are also discussed here.
