<p>Intracellular motions are important signatures of living tissues, and intracellular dynamics reflect overall cell function and health. Traditional microscopy methods can track 2D cellular motions but do not provide an ensemble evaluation of intracellular activity. Biodynamic imaging (BDI) is a unique 3D imaging technique based on the phase shifts of dynamic light scattering and is highly sensitive to intracellular dynamics in living cells and their changes. This makes BDI a versatile tool to evaluate many different types of samples under various scenarios, and BDI has the potential to improve patient diagnosis and to provide valuable information for health care research. This may include evaluating sample activity, profiling patient chemotherapy response, and studying drug mechanisms. This thesis discusses the theory and modeling of BDI, the construction of BDI systems, sample heterogeneity analysis (TDSI), and the use of BDI to study cytoskeletal drug mechanisms, improve embryo selection and select therapies in pre-clinical trials.</p>