Determining blood platelet morphology modelled by a superellipsoid from the solution of the inverse light-scattering problem

•The superellipsoid model is statistically superior to the oblate spheroid model for 60% of platelets.•Precision of recognized platelet fractions is increased by suggestion of superellipsoid model.•The inverse light scattering problem was solved faster using the hybrid method.•The DIRECT method employs linear interpolation between the regular database node. In this work, we propose a new optical model to describe the morphology of a platelet in the form of a special axisymmetric superellipsoid. This model is more general than the widely used classical oblate spheroid model of the platelet and includes the oblate spheroid as a special case. The inverse light scattering (ILS) problem within the developed optical model was solved using the light scattering profile (LSP) of individual platelets obtained by the scanning flow cytometer. Solving the ILS problem we used a hybrid method that combines the DIRECT algorithm of global optimization with the linear interpolation between the nodes of the pre-calculated regular database of superellipsoid LSPs. The statistical F-test shows that the new optical model is better than the conventional oblate spheroid model in more than 60 percent of cases. This made it possible to obtain the refined shape index distributions for platelets consisting of three fractions, namely resting, partially and fully activated platelets.