INTERCOMPARISON OF RADIOTHERAPY TREATMENT PLANNING SYSTEMS FOR EXTERNAL PHOTON AND ELECTRON-BEAM DOSE CALCULATIONS

Dose distributions calculated by six different treatment planning syst ems (TPSs), used by the hospitals in Finland or in Russia, were compar ed with measured dose distributions. Five typical cases of irradiation were selected: regular fields, oblique incidence, irregular field, we dge field and inhomogeneity in a water equivalent phantom. The beam da ta for each TPS where those pertaining to the beam where the comparati ve relative measurements were performed. The results indicate that the dose distributions produced by different TPSs can differ from each ot her as well as from the measured dose distributions up to a level whic h is not acceptable in terms of the ICRU recommendations. Greatest dif ferences seem to be related to the omission or undue consideration of the scatter components of the beam.