SHIELDING CALCULATIONS FOR A 250 MEV HOSPITAL-BASED PROTON ACCELERATOR

The accelerator shields (250 MeV protons, 400 MeV/u O-16(8+) ions) and treatment rooms of the Hadrontherapy Centre, a hospital-based facilit y under design in Italy, were determined by means of Monte Carlo calcu lations. The LCS and FLUKA codes were employed, together with analytic al estimates carried out by making use of empirical formulas from the literature, and the results: compared. In the case of 250 MeV protons a 250 cm thick concrete wail ensures an annual dose equivalent lower t han 2 mSv in the environments adjacent to thr accelerator room. The be st ceiling thickness was found to be 200 cm for a unitary occupancy fa ctor. The photon dose equivalent beyond the concrete shield was also e stimated using the LCS code. In the case of ions the shield thickness was calculated using empirical formulas from the literature; the concr ete thicknesses calculated fur protons should ensure the required dose equivalent when some local shields are added, Monte Carlo calculation s of the treatment room shielding were also carried our using the FLUK A code.