Cluster models in cellular level electron dose calculations

Abstract

A program for calculating absorbed dose was developed for radioimmunotherapy (RIT) purposes. It was used to determine the difference in the therapeutic effect of 111In electrons when using a close-packed cubic geometry and a cell cluster model developed in this project. Our cluster model piles the cells individually. The cells were modelled as spheres of diameters of 12 (tumour) and 30 (healthy) μm. Both models were used to generate clusters with spherical tumours inside healthy tissue. The program uses Monte Carlo-based dose kernels. The radiation spectra were calculated from the Auger and x-ray transition strengths and fluorescence yields of 111In. The results show the importance of the cluster model in cellular level dose calculations. Near the tumour/healthy tissue interface in particular, the doses differ because of geometrical differences. In the case of a small cluster with tumour and total diameters of 30 and 150 μm, the ratio of the therapeutic effects is 20.