Generalized Student's t-distribution mixtures for autoradiographic image spread modelling

In this paper a new class of models for autoradiographic hot-line data is proposed. The models, for which there is theoretical justification, are a linear combination of generalized Student’s t-distributions and have as special cases all currently accepted line-spread models. The new models are used to analyse experimentalhot-line data and compared with the fit of current models. The data are from a line source labelled with iodine-125 in a resin section of 0.6 m in thickness. It will be shown that a significant improvement in goodness of fit, over that of previous models, can be achieved by choosing from this new class of models. A single model from this class will be proposed which has a simple form made-up of only two components, but which fits experimental data significantly better than previous models. A short sensitivity analysis indicates that estimation is reliable. The modelling approach, although motivated by and applied to autoradiography, is appropriate for any mixture modelling situation.