Bifocal technique for accurate measurement of total attenuation coefficient in scattering media with OCT

Accurate measurements of tissue optical properties are needed for many diagnostic and therapeutic applications of optical techniques. OCT recently proposed for high-resolution imaging in tissue can potentially be applied for accurate and noninvasive measurement of tissue optical properties. We proposed a bifocal technique for accurate measurement of tissue total attenuation coefficient with OCT. This technique utilizes detection of OCT signals from two focal planes within scattering media that allows correction for confocal function. In this paper, we studied the capability of the bifocal technique to measure accurately total attenuation coefficient in scattering media simulating tissue with high and low scattering. The experiments were performed with tissue phantoms: suspension of polystyrene microspheres in water with different total attenuation coefficients. Our studies demonstrated that the bifocal technique substantially improves accuracy of measurement: absolute values of total attenuation coefficient can be measured with 7% accuracy (compared with theoretically calculated values), while the accuracy of relative measurements can be 1.5%. Our results indicate that the bifocal technique is a promising approach to accurate measurement of total attenuation coefficient in tissues.