Employing the Optical Model of an "Oblate Spheroid" to Approximate the Shape of an Activated Platelet

The determination of morphological parameters of individual platelets is of great scientific and practical interest in the field of medical applications. However, the accuracy of determining these parameters based on light scattering data depends not only on the quality of the initial experimental data and the methodology used to solve the inverse problem of light scattering, but also on the optical model employed for platelets. The choice of an appropriate optical model is crucial as it directly influences the accuracy of the determined parameters. A significant mismatch between the assumed optical model and the actual shape of the measured particle can introduce uncontrolled systematic errors, thereby compromising the adequacy and validity of the study's findings. This paper focuses on assessing the impact of such errors on the shape parameters using two specific examples of platelet geometric shapes. These shapes were deliberately chosen to deviate from the commonly employed optical model, which assumes uniform oblate spheroids. The first geometric configuration investigated was derived from a biophysical model that represents the morphology of a platelet. This model was obtained through the optimization of surface area while keeping the internal volume constant. The surface was defined by a mathematical curve characterized by a consistent curvature. The second geometric structure was artificially constructed by augmenting an oblate spheroid with elongated halves of ellipsoids, specifically designed to imitate pseudopodia.Numerically calculated light scattering signals obtained through the ADDA software package were used as experimental data, and these signals were subsequently adjusted to resemble the type of signals obtained from light scattering measurements conducted on a scanning flow cytometer.