Abstract

In this dissertation measurement of the scattering properties of Intralipid phantoms are considered using the diffuse optical method. As constructing phantoms with known optical properties are of great importance for calibration of optical imaging devices it is vital to measure the optical properties of the constructing materials of the phantoms. Intralipid is a material widely used for making biological phantoms and it is used as the scattering section. This substance has very high scattering coefficient and very low absorbing coefficient for near infrared light. To make the absorbing section, Indian ink is usually used and its absorbing coefficient is usually investigated using a common method. However, to measure the scattering coefficients of Intralipid, optical imaging methods should be deployed. In this dissertation, first a method using the optical imaging device for measuring the reduced scattering coefficient of Intralipid phantoms is discussed and then another method for measuring the scattering coefficient of pure Intralipid medium is mentioned, finally a more sophisticated method using the frequency domain method is proposed. The results of the two first methods are discussed and they are used for investigating the ingredients of the Intralipids made by two different companies. Also the improvements in the performing of the frequency domain method are reported. The proposed methods are capable of measuring the scattering and the reduced scattering coefficient of the Intralipid medium. The results suggest corrections to the common formulae for calculating the scattering coefficients of Intralipids purchased in Iran, they aslo reveal some information about the ingredients of these Intralipids. The results make clear that the optical properties of any Intralipid purchesed for laboratory work should be investigated before use.

Keywords: Intralipid, Diffuse optical imaging, Reduced scattering coefficient, Frequency domain method, Electronic filters, Frequency mixing electronic circuits, Phase detection electronic circuits