<title>Near-infrared optical coefficients of tumors and adjacent normal tissue</title>

Abstract

The absorption and reduced scattering coefficients of tumours of the human breast, liver and kidney and their normal surrounding tissue have been measured in vitro for the near-infrared wavelengths between 600 and 1000 nm as well as 1064 nm. The Monte Carlo inversion technique (Simpson et al) was used to determine the optical coefficients of tissue samples from measurements of the diffuse transmittance and reflectance. The measurements of the diffusely transmitted and reflected intensities were performed using a single integrating sphere 'comparison' method. Four post-mortem samples of both liver adenocarcinoma and normal liver tissue were obtained from one subject and four samples of both tumour and normal kidney tissue were obtained from another subject. Four samples of both breast tumour and normal tissue were obtained from two patients. The scattering coefficient of tumours was found in each case to be significantly higher than that of nondiseased tissue. The absorption coefficient of tumours was generally much smaller than those of normal tissue. The scattering coefficient of tumours was 20% to 200% higher depending on the type of cancer and the wavelength, while the absorption coefficient of tumours was as much as twenty times smaller compared to normal tissue.