Dual-Energy Digital Mammography with a Full-Field aSi/CsI Flat-Panel Imager

摘要

The large goals of this project are to develop and investigate dual- energy subtraction imaging technique for use with an amorphous silicon/cesium iodide based flat panel digital mammography system. With this technique, cluttered tissue structures can be cancelled out to enhance the detection and visualization of microcalcifications. In the first year, we have performed necessary theoretical and numerical studies to investigate the calcification signal-to-noise ratio in the subtraction image as a function of x-ray spectrum combination, exposure distribution, scintillator material, calcification thickness, breast thickness and tissue composition. We have demonstrated with numerical computations that with 1000 mR un-attenuated total exposure at detector, the proposed dual-energy technique can be used to image and detect calcifications as small as 250 microns. We have also shown that 25 kvp Mo/Mo and 50 kvp W/La x-rays would provide optimal spectrum combination for best calcification SNR in the subtraction image. To prepare for actual implementation and further investigation, we have also measured, modeled and validated image signal as a function of x-ray technique, breast thickness and breast composition. Current mean glandular dose calculation has been extended to high kvp applications.