The Design and Emulation of a Multiple-Camera SPECT Breast Imager

This report summarizes the work completed in Year 1 of this grant. The work included characterizing radioactivity within the breast building phantoms for imaging modeling the detector response and optimizing the imaging system geometry. Standard clinical injections of Tc-99m Sestamibi contain 20 mCi of activity. The estimated percentage of the activity taken up by a single breast of average mass is about 0.08 %, which corresponds to about 16 uCi. The estimated activity per unit mass of normal breast tissue is 43 dpm/mg. The uptake of Tc-99m Sestamibi in abnormal breast tissues (relative to normal tissue) was examined. The degree of uptake varied significantly with the histological type (not grade) of malignant tumors. The mean responses of the small and large modular cameras were characterized. An optical model providing estimates of the camera response to gamma rays incident anywhere on the camera face, was developed.