A prototype for laser mammography based on a time-domain technique has been developed. The system uses a streak camera and a Titanium:sapphire laser which provides ultrashort pulses at a repetition rate of 80 MHz. A multi- port scanning head which includes optical fibers scans the breast in a point-by-point scanning procedure. Time-resolved transmission is measured at 15000 locations in 7 minutes. The breast is slightly compressed in both the cranio-caudal and the mediolateral projections. Amplitude calibration of the streak camera has been performed allowing for absolute measurement of time-resolved transmission. In addition to the shape of the time-resolved transmission, the absolute amplitude is relevant in properly evaluating the absorption and scattering coefficients. Promising results on solid phantoms and in vivo have been obtained. Both breasts of 10 volunteers have been scanned to date and a larger pilot study is planned in the near future. In addition to the usual time-gating processing, images of the scattering and absorption contributions are also extracted using an original data processing technique.
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