Application of FLUKA code to gamma-ray attenuation, energy deposition and dose calculations

Background: In radiation therapy, water is the phantom material of choice, both for reference and for relative dosimetry measurements. Solid phantoms, however, are more useful for routine measurements because they tend to be more robust and easier to set up than water phantoms. Materials and Methods: FLUKA input data cards have been arranged in sequential order. A simple cylindrical geometry with the axis along the z-direction was described in the input file. A beam of 1x105 gamma-rays was directed towards the materials in the z-direction. The results of photon transmission, I/I0, were obtained from output files for each of the material thicknesses using the USRBDX score card. The USRBIN score card was also included in the input file, and the energy deposited by 661.6 keV photons into water and solid phantom materials has been obtained. Results: The values of linear attenuation coefficients calculated by FLUKA are closer to experimentally obtained ones. The values of the linear attenuation coefficients derived from XCOM are greater than those derived from the FLUKA transmission data. The values of dose absorbed in Perspex are smaller than those of other materials, which are closer to each other.  Conclusion: RMI-457, plastic water and RW solid phantoms can be used for radiation dosimetry of photons in the energy range from 59.5 to 1332.5 keV. From the investigation of absorbed dose values versus thickness of absorber, Perspex is not a suitable equivalent to water for the tested energies.