Abstract
Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate specific tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with specific optical properties of each layer. However, such a structure is not always addressed in the present-day phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coefficient [Formula: see text] and absorption coefficient μa) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide ( ZnO ) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching was found between optical properties of phantoms and the corresponding values found in the literature.
Highlights
Noninvasive diagnostics is aimed to provide information about internal parameters of living subjects, which may revolutionize medical diagnostics
The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide (ZnO) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties
Use of real human tissues is impractical since the optical properties of such samples change in various atmospheric conditions and rapidly degrade over time, they are unusable as standards with known and stable properties
Summary
Noninvasive diagnostics is aimed to provide information about internal parameters of living subjects, which may revolutionize medical diagnostics. Properties of phantoms di®er depending on the purpose they are designed for, as various noninvasive optical diagnostic techniques utilize phantoms.[5,6,7,8,9,10,11,12,13,14] The geometry of the head-mimicking phantoms used previously is not complex being either in a form of a slab,[15] a cylinder,[16] a container,[17] a plastic skull.[18] Phantoms with more sophisticated geometry simulating a head shape and the brain are under developed.[19] The structure of optical phantoms usually comprises three parts.[5,6,20] First, the matrix material, which is chosen with regards to its mechanical properties, refractive index, and stability over time Another constituent, the scattering component, is used to a®ect scattering properties of the phantom. Most common scatterers are TiO2 nanoparticles,[5,6,11] plastic microspheres,[5,21,22] or lipids.[23,24,25] To a®ect absorption, absorbing agents such as ink, whole blood,[26] or dyes[21] are used
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