Paraxial analysis of light scattering by biological cells in a flow system

A special mathematical model is developed to find the scattered light pattern of biological cells in a fluid flow system. A paraxial approximation to the diffraction integral is used to accommodate nonspherical and asymmetrical cells. The paraxial approximation results are in good agreement with Mie calculations for homogeneous spheres of comparable size and refractive index. A 2-D fast Fourier transform program is used to simulate variable cell morphology and experimental conditions. Distinct signature differences for two types of cells resembling normal and abnormal malignant human cervical cells are found useful as discriminant features. The ability to handle a variety of model cell shapes and distortions by these methods is demonstrated, and use of signature features for cell discrimination is shown experimentally.