Instrumentation and clinical applications in frequency-domain optical mammography

We describe an instrument for frequency-domain light mammography (LIMA), and we present clinical results obtained on patients affected by breast cancer. This instrument uses two laser diodes emitting at 690 and 825 nm. Their intensities are modulated at a frequency of 110 MHz. The amplitude and the phase of the intensity wave are the measured quantities. The breast is slightly compressed between two glass plates and the optical signal is detected in transmission, i.e. on the opposite side of the illuminated spot of the breast. The acquisition time for a full breast image is about 3 minutes. Edge effects (that are mainly due to the breast thickness variability within the scanned area) are corrected by an algorithm of data analysis which enhances the contrast of the optical mammograms. In the clinical applications, we successfully detected 27 out of 37 malignant tumors (73%). This result shows the practical feasibility and the significant potential of frequency-domain optical mammography.