title: Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT.
abstract: In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of nonmaterial-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA. yu.lifeng@mayo.edu
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yu
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Primak
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
mesh_terms: D000328:Adult; D055592:Biophysical Phenomena; D049628:Body Size; D006801:Humans; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data