Uniform depth dose distribution for biological irradiation using negative pions

A simple, flexible technique has been developed to generate uniform depth dose profiles for the biomedical pion beam at TRIUMF using dynamic momentum control and linear programming. Either the entrance dose or the irradiation time required for a certain dose over the uniform region can be minimised. The dynamic momentum control can operate automatically under computer control even with a highly unstable beam. Cell survival profiles have been obtained for this uniform dose distribution using the gelatin technique. The RBE increased with increasing depth through the uniform dose region. (author)