Optimization of a dual-energy contrast-enhanced technique for a photon counting digital breast tomosynthesis system

We have developed a dual-energy technique for contrast-enhanced digital breast tomosynthesis using a photon-counting imaging system whereby low- and high-energy images are acquired in a single scan. A W target x-ray source is employed at 49 kV. Sn and Cu filters are used to obtain low- and high-energy images. Iodine enhanced images are caluclated by applying a weighted subtraction to the logarithm of the Sn and Cu images. The optimal system configuration and Sn-Cu filter pair were assessed using theoretical modeling. The mean glandular dose was kept to 1 mSv. Optimal weighting factors (w(t)) for the subtraction and SDNR between iodine-enhanced and non-enhanced breast background were caluclated. Optimal w(t) and SDNR depend on the Sn-Cu combination and breast thickness. SDNR varies with the dose allocated among the Sn and Cu images. The optimal configuration uses Sn and Cu filters of sufficient thickness to require the maximum mAs achievable by the x-ray tube.