title: Optimization of K-edge imaging for vulnerable plaques using gold nanoparticles and energy resolved photon counting detectors: a simulation study.
abstract: We investigated the effect of different imaging parameters, such as dose, beam energy, energy resolution and the number of energy bins, on the image quality of K-edge spectral computed tomography (CT) of gold nanoparticles (GNP) accumulated in an atherosclerotic plaque. A maximum likelihood technique was employed to estimate the concentration of GNP, which served as a targeted intravenous contrast material intended to detect the degree of the plaque's inflammation. The simulation studies used a single-slice parallel beam CT geometry with an x-ray beam energy ranging between 50 and 140 kVp. The synthetic phantoms included small (3 cm in diameter) cylinder and chest (33 × 24 cm(2)) phantoms, where both phantoms contained tissue, calcium and gold. In the simulation studies, GNP quantification and background (calcium and tissue) suppression tasks were pursued. The x-ray detection sensor was represented by an energy resolved photon counting detector (e.g., CdZnTe) with adjustable energy bins. Both ideal and more realistic (12% full width at half maximum (FWHM) energy resolution) implementations of the photon counting detector were simulated. The simulations were performed for the CdZnTe detector with a pixel pitch of 0.5-1 mm, which corresponds to a performance without significant charge sharing and cross-talk effects. The Rose model was employed to estimate the minimum detectable concentration of GNPs. A figure of merit (FOM) was used to optimize the x-ray beam energy (kVp) to achieve the highest signal-to-noise ratio with respect to the patient dose. As a result, the successful identification of gold and background suppression was demonstrated. The highest FOM was observed at the 125 kVp x-ray beam energy. The minimum detectable GNP concentration was determined to be approximately 1.06 µmol mL(-1) (0.21 mg mL(-1)) for an ideal detector and about 2.5 µmol mL(-1) (0.49 mg mL(-1)) for a more realistic (12% FWHM) detector. The studies show the optimal imaging parameters at the lowest patient dose using an energy resolved photon counting detector to image GNP in an atherosclerotic plaque.
authors: Yahya
authors: Y
authors: Alivov
authors: Pavlo
authors: P
authors: Baturin
authors: Huy Q
authors: HQ
authors: Le
authors: Justin
authors: J
authors: Ducote
authors: Sabee
authors: S
authors: Molloi
mesh_terms: D002104:Cadmium; D006046:Gold / Q000737:chemistry* / Q000378:metabolism*; D053768:Metal Nanoparticles; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D017785:Photons; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D019904:Polymethyl Methacrylate; D012588:Scintillation Counting / Q000379:methods*; D059629:Signal-To-Noise Ratio; D013691:Tellurium; D014057:Tomography, X-Ray Computed / Q000379:methods*; D015032:Zinc
chemical_list: C474490:CdZnTe; D002104:Cadmium; D006046:Gold; D019904:Polymethyl Methacrylate; D015032:Zinc; D013691:Tellurium