Radiation chemical and magnetic resonance studies of aqueous agarose gels containing ferrous ions

Aqueous agarose gels containing ferrous ions sustain a radiolytic chain reaction, producing Fe3+. G(Fe3+)-values up to 156 have been observed, independent of dose rate between 0.434 and 3.74 Gy min-1. Dissolved oxygen is needed to maintain the chain reaction, and initial ferric yields are increased if the gel is oxygen saturated, or if the Fe2+ concentration is decreased. Longitudinal proton magnetic relaxation rates are increased in proportion to ferric production, permitting visualizing of dose levels in these gels by magnetic resonance imaging techniques. There is a potential for application to radiation therapy treatment planning. (author)