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This work investigates a dual-energy subtraction technique for cone-beam breast CT combined with an iodinated
contrast agent. Simulations were performed to obtain optimally enhanced iodine-equivalent and morphological images.
The optimal x-ray beam energies and average glandular dose allocation between the LE and HE images were identified.
Cylindrical phantoms were simulated with 10, 14 and 18 cm diameters and composed of 50% fibroglandular breast tissue
equivalent material. They contained spherical lesion inserts composed of 0, 25, 75 and 100% fibroglandular equivalent
tissues, homogeneous mixtures of 50% fibroglandular equivalent tissue and 0.5, 1.0, 2.5 and 5.0 mg/cm3 iodine, as well
as pure calcium hydroxyapatite, emulating calcifications. An acquisition technique with 600 projection images is
proposed. Only primary x-ray photons were simulated and a perfect energy-integrating detector was considered. LE and
HE beams ranging from 20 keV to 80 keV were investigated. The LE and HE projections were reconstructed using a
filtered backprojection algorithm. The LE volume provided the morphological image while the iodine-equivalent volume
was obtained by recombining the LE and HE volumes. Contrast-to-noise ratio (CNR) between the spherical inserts and
background breast tissue normalized to the square root of the total AGD (CNRD) was used as figure-of-merit for lesion
detectability. Based on maximizing CNRD, a 30keV/34keV LE/HE pair and a ~50/50% LE/HE AGD allocation were
found to provide the best possible performance for iodine and morphological imaging for an average size breast.
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