Static and dynamic light scattering properties of Intralipid aqueous suspensions for tissue phantom preparation and calibration. I. Delfino a , R. Esposito b , B. Piccirillo b , G.M. Gaeta c , M. Lepore d a Biophysics and Nanoscience Centre, CNISM, Facoltà di Scienze, Università della Tuscia, Viterbo, Italy b Dipartimento di Scienze Fisiche, Università”Federico II”, Napoli, Italy c Dipartimento di Scienze Odontostomatologiche, , Seconda Università di Napoli, Napoli, Italy d Dipartimento di Medicina Sperimentale, Seconda Università di Napoli, Napoli, Italy Abstract Intralipid is a material widely employed for the preparation of phantoms simulating optical properties of tissues in the field of optical imaging. Two main assumptions underlie the theoretical predictions of their scattering properties: the occurrence of single scattering for any concentrations of Intralipid, thus enabling the use of Mie theory, and a highly anisotropic g-factor giving a forward preferential direction of photon propagation. The importance of precisely estimating the optical properties of such phantoms requires that the accuracy of these assumptions and their range of applicability are very well-assessed. In this paper, we report the first step of an experimental investigation on the scattering properties of Intralipid suspensions at different concentrations. The study is carried out by the joined use of Time-Resolved Transmittance and Dynamic and Static Light Scattering techniques. By the analysis of the angular and temporal dependence of light scattered by Intralipid suspensions, a more reliable description of the scattering process occurring in the samples could be obtained. The results allow us to better elucidate the dependence of scattering properties of suspensions on Intralipid concentrations and composition. This will help in the design and realization of tissue phantoms with more and more reliable optical properties. Keywords: Light scattering, Turbid Media, Intralipid, Static and Dynamic optical properties INTRODUCTION The development of new optical diagnostic techniques requires the use of well-designed tissue phantoms for all the pre clinical stages of investigations [1,2]. For phantoms with scattering properties similar to biological tissues (turbid media), Intralipid is largely employed because it is easy to find and handle and it has a low price [3-5]. Notwithstanding these significant advantages it is not an optical standard and then more efforts are still required to better characterize its scattering properties. As well known, light scattering in turbid media is an attractive field both from a fundamental and an applicative point of view. In fact, new interesting phenomena, as coherent backscattering and weak localization [6], have been recently discovered and important applications as medical imaging and diffusing-wave spectroscopy are now largely under development [7]. Photons propagating inside turbid media can undergo to elastic, quasi-elastic and inelastic scattering processes. Every one of these processes has allowed the development of many useful experimental techniques giving information on scattering and structural parameters of investigated samples. For example, the elastic scattering processes can be analysed from static and dynamic points of view using static light scattering (SLS) apparatus and time-resolved transmittance and reflectance experimental set-ups. The simultaneous use of these two experimental approaches provides a deeper insight into the relationship between static and dynamic scattering properties. In fact, the main results of steady-state light scattering experiments are about static scattering properties (for example, the transport mean free path) while the outcomes of time-resolved experiments are dynamic scattering parameters (for example, the diffusion coefficient). Accordingly, the experimental investigation of the relation between these two classes of parameters, performed on very peculiar systems, has allowed the researchers to better understand the above-mentioned Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurements of Tissue, edited by Robert J. Nordstrom, Proc. of SPIE Vol. 6870, 68700P, (2008) · 1605-7422/08/$18 · doi: 10.1117/12.769364 Proc. of SPIE Vol. 6870 68700P-1 2008 SPIE Digital Library -- Subscriber Archive Copy