NONINVASIVE MEASUREMENTS OF BREAST-TISSUE OPTICAL-PROPERTIES USING FREQUENCY-DOMAIN PHOTON MIGRATION

A multiwavelength, high bandwidth (1 GHz) frequency-domain photon migr ation (FDPM) instrument has been developed for quantitative, non-invas ive measurements of tissue optical and physiological properties. The i nstrument produces 300 kHz to 1 GHz photon density waves (PDWs) in opt ically turbid media using a network analyser, an avalanche photodiode detector and four amplitude-modulated diode lasers (674 nm, 811 nm, 84 9 nm and 956 nm). The frequency-dependence of PDW phase and amplitude is measured and compared to analytically derived model functions in or der to calculate absorption, mu(a), and reduced scattering, mu'(s), pa rameters. The wavelength-dependence of absorption is used to determine tissue haemoglobin concentration (total, oxy- and deoxy- forms), oxyg en saturation and water concentration. We present preliminary results of non-invasive FDPM measurements obtained from normal and tumour-cont aining human breast tissue. Our data clearly demonstrate that physiolo gical changes caused hv rile presence of small (about 1 cm diameter) p alpable lesions can be detected using a handheld FDPM probe.