MONTE-CARLO CALCULATIONS OF FIELD PARAMETERS FOR THE ICRU SPHERE WITH REFERENCE PHOTON BEAMS

The need to characterise the photon radiation field in the presence of a suitable phantom like the ICRU sphere for the design of personal dosemeters motivated an extensive amount of MCNP Monte Carlo calculations. Air kerma backscatter factors, mean energy of the backscattered radiation relative to angle of the incident beam as well as the backscattered fluence spectra for ISO and BIPM incident reference radiations were calculated for energies between 7 keV and 250 keV and for Cs-137 and Co-60. Backscatter factor values for different angles of the incident beam were also experimentally evaluated and compared with the corresponding data obtained by Monte Carlo calculations.