The Pretoria cyclotron facility

Intercomparison measurements were performed at the MRC Cyclotron, Clatterbridge (U.K.). Discrepancies between the previously stated doses of Hammersmith Hospital, London and the doses measured at NAC (Pretoria) have been resolved with the introduction of a simple correction factor. Spectral energy measurements have been performed in air at SSD and in-phantom for the neutron therapy beam. The average energy En of the in-air spectrum together with values for the average kerma ratio (Kt/Km)N and the ratio of the average energies required to create an ion pair in the A150/TE gas ionization chamber were determined. Cognizance regarding radiation protection measures has been taken concerning recent ICRP recommendations doubling the quality factor for fast neutrons. Modifications to the safety interlock system of the neutron therapy facility were implemented to allow for the independent use of the kilocurie 60Co radiation unit. 2 figs., 13 refs