The effects of cold storage on double integrating sphere optical properties measurements of porcine skin and subcutaneous fat

Accurate values of the optical properties of skin and subcutaneous fat are important for a variety of applications, such as optical imaging techniques and computational modeling of possible hazardous laser exposure. Several studies are available in the published literature that report skin optical properties, but the method of tissue preparation and storage in these experiments can be variable. These methods include the application of some form of cold storage, such as refrigeration or freezing, which may in turn affect the optical properties of the tissues compared to the in vivo or freshly excised case. We measured the absorption and scattering coefficients of skin and subcutaneous fat samples prior to and following various methods of cold storage, particularly refrigeration, slow freezing, and flash freezing. Tissues were collected from two subjects in order to capture biological variability. We employed a double integrating sphere setup and the inverse adding-doubling method to determine optical properties. The results of this investigation will help contextualize existing studies on tissue optical properties and enable informed procedural design for future measurements.