CONVENTIONAL AND MICROBEAM STUDIES USING LOW-ENERGY CHARGED-PARTICLESRELEVANT TO RISK ASSESSMENT AND THE MECHANISMS OF RADIATION ACTION

A study of the effectiveness of low energy charged particles has shown that in the LET range 20-38 keV mu m(-1), protons and deuterons are m ore effective than alpha particles of equivalent LET. These difference s may reflect dissimilarities in the track structures and have importa nt consequences both for mechanistic studies and risk assessment. This work will underpin investigations into mechanisms of radiation action and extreme low dose responses using a charged particle microbeam. Th is facility will enable cells to be irradiated individually using sing ly and doubly charged particles. Using this approach it is possible to devise in vitro models that are a more realistic representation of th e situation relevant to environmental exposures to charged particles w here single particle effects predominate. With sufficient spatial reso lution (at present 5 mu m, but with similar to 1 mu m in prospect) the microbeam will also be useful in addressing observations related to c ellular spatial sensitivity, for example, the identification of critic al sub-cellular targets.