Absorbed dose conversion factor in the farmer type ionization chamber

Monte Carlo simulations can be approximated considering the environment of actual measurement in detail. However, it can not be completely corrected by simulations. Because there are some uncertainties on the actual measurement. For example, the amount of charge using the ionization chamber is used to convert the dosimeter measurement of the absorbed dose by the exposure calibration factor for cobalt-60 and the absorbed dose conversion factor. In the simulation, absorbed dose is seeking direct energy per unit mass of water, on the other hand, it is converted to energy per unit mass of water from the charge amount in the air by the exposure calibration factor for cobalt-60 and the absorbed dose conversion factor in actual measurement. We suspect these factors containing uncertainties. Focusing on the absorbed dose conversion factor, we investigated it by EGS5. We specialized microSelectron-HDR v2 as a radiation source and PTW TN30013 as an ionization chamber.