The Clatterbridge high-energy neutron therapy facility: measurements of beam parameters for clinical use.

Measurements have been performed on the 62 MeV proton cyclotron at the Douglas Cyclotron Centre, Clatterbridge Hospital, to determine the variation in beam parameters necessary for clinical use of the neutron therapy facility. These measurements are of total (neutron and gamma) doses, and include: depth doses for wedged and unwedged fields at various treatment distances; profile measurements and the production of associated isodose charts; calibration of the dosimetry system of the cyclotron; and determination of variations in calibration associated with changes in field size, wedge and focus-skin distance. Measurements have also been performed to estimate the degree of long-term stability of both calibration and field uniformity.