Precision localization of hidden absorbers in body tissues with phased-array optical systems

Abstract

The recurrent difficulties of rapidly localizing a small object in a large volume of highly scattering material such as brain and breast has been the ‘‘stumbling block’’ of optical methods for tumor detection. Amplitude cancellation of in- and out-of-phase photon diffusion patterns, used in detection of small objects containing highly absorbing and fluorescing contrast agents provides real time, two- and three-dimensional localization of objects of mg size and picamole contents in models of human breast and brain tumors with positional accuracies of millimeters. A simple robust electronic circuit is described and tested to give a phase accuracy of ∼0.1°. An electro-optical scan rapidly detects small objects in a large volume that simulates the absorption/scattering characteristics of human head or breast.