FEASIBILITY STUDY FOR POSITRON EMISSION MAMMOGRAPHY

A feasibility study is presented for a small, low-cost, dedicated devi ce for positron emission mammography. Two detector arrays above and be low the breast would be placed in a conventional mammography unit. The se detectors are sensitive to positron annihilation radiation, and are connected to a coincidence circuit and a multiplane image memory. Ima ges of the distribution of positron-emitting isotope are obtained in r eal time by incrementing the memory location at the intersection of ea ch line of response. Monte Carlo simulations of a breast phantom are c ompared with actual scans of this phantom in a conventional PET scanne r. The simulations and experimental data are used to predict the perfo rmance of the proposed system. Spatial resolution experiments using ve ry narrow bismuth germanate BGO crystals suggest that spatial resoluti ons of about 2 mm should be possible. The efficiency of the proposed d evice is about ten times that of a conventional brain scanner. The sca tter fraction is greater, but the scattered radiation has a very flat distribution. By designing the device to fit in an existing mammograph y unit, conventional mammograms can be taken after the injection of th e radio-pharmaceutical allowing exact registration of the emission and conventional mammographic images.