An image-based approach to measure the ferric ion diffusion coefficient in fricke gel dosimetry

A numerical method was adopted to solve the diffusion equation to determine ferric ion diffusion coefficient in Fricke-agarose gels. A fast MR acquisition technique was employed to avoid smearing of acquired data due to diffusion over an extended time period. Our results show that for a Fricke gel contained 1 mM ammonium ferrous sulfate, 1% agarose, 1 mM sodium chloride and 50 mM sulfuric acid, its ferric ion diffusion coefficient is 1.73 10^-2cm²h^-1in room temperature. This value is consistent with the 1 ~ 2 10^-2cm²h^-1range obtained by previous studies under varying concentrations of gel ingredients.