Dual-energy CT imaging over non-overlapping, orthogonal arcs of limited-angular ranges

BACKGROUND: Interest exists in dual-energy computed tomography (DECT) imaging with scanning arcs of limited-angular ranges (LARs) for reducing scan time and radiation dose, and for enabling scan configurations of C-arm CT that can avoid possible collision between the rotating X-ray tube/detector and the imaged subject. OBJECTIVE: In this work, we investigate image reconstruction for a type of configurations of practical DECT interest, referred to as the two-orthogonal-arc configuration, in which low- and high-kVp data are collected over two non-overlapping arcs of equal LAR α, ranging from 30° to 90°, separated by 90°. The configuration can readily be implemented, e.g., on CT with dual sources separated by 90° or with the slow-kVp-switching technique. METHODS: The directional-total-variation (DTV) algorithm developed previously for image reconstruction in conventional, single-energy CT is tailored to enable image reconstruction in DECT with two-orthogonal-arc configurations. RESULTS: Performing visual inspection and quantitative analysis of monochromatic images obtained and effective atomic numbers estimated, we observe that the monochromatic images of the DTV algorithm from LAR data are with substantially reduced LAR artifacts, which are observed otherwise in those of existing algorithms, and thus visually correlate reasonably well, in terms of metrics PCC and nMI, with their reference images obtained form full-angular-range data. In addition, effective atomic numbers estimated from LAR data of DECT with two-orthogonal-arc configurations are in reasonable agreement, with relative errors up to ∼ 10%, with those estimated from full-angular-range data in DECT. CONCLUSIONS: The results acquired in the work may yield insights into the design of LAR configurations of practical dual-energy application relevance in diagnostic CT or C-arm CT imaging.

Measurement Mass Attenuation Coefficient of Palmitic Acid by Using Sources of Gamma Ray

The purpose of this paper is to determine the mass attenuation coefficient (μ/ρ), of a sample. In this work used (C16H32O2) fatty acid, exposed to gamma rays (γ), emitted from various sources 57Co, 133Ba, 22Na, 137Cs, 54Mn, and sCo with energies from 0.122 to 1.330 MeV. It exposes the compound to gamma rays and discloses the radiation force that passes through the sample, the rest of the gamma radiation attenuated. A NaI fluorescence detector (Tl) with an accuracy of 8.2% (at 662 kV) was used for the gamma ray detector beam. An advantage of using (μ/ρ) coefficient data can be obtained effective atomic numbers, atomic cross-section and effective electron densities.

Photon attenuation parameters of non-essential amino acids using EPICS2017 library interpolations

Mass attenuation coefficients, effective atomic numbers, electron densities and energy absorption and exposure buildup factors for the non-essential and conditionally non-essential amino acids including alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine have been acquired using the latest evaluated photoatomic library of EPICS2017. The library was used by constructing an interpolation script that calculates for all photon attenuation parameters. Comparisons were made using alternative Monte Carlo simulation results for 15 energy points from 59.5 to 1333 keV, and in contrast with experimental works in literature. Good agreements for the mass attenuation coefficients were observed between EPICS2017-based values compared with Monte Carlo code and experimental results. Similar trends for the effective atomic numbers and electron densities were observed from EPICS2017 interpolation and from results found in literature. Conversely, buildup factors acquired by Geometric-Progression fitting parameters were reported in this work preliminarily for most of these biomolecules at different penetration depths. Overall, cysteine showed the most significant deviation among the other non-essential amino acids due to the presence of sulfur in its molecular structure.

Investigation of the Mass Attenuation Coefficients, Effective Atomic Numbers and Electron Densities for Compounds of Painkiller

In this study the effects of gamma radiations with compounds are an important subject in the field of medicine, radiation shielding and radiation physics. With technological advances the using of radiation has increased in the medicine in the last century. The mass absorpsion coefficient (µ/ρ) is the fundamental a quantity characterizing gamma ray and is of major importance in radiation shielding. In this study, the mass absorption coefficient of painkillers named Ketoprofen, Flurbiprofen, Etodolac, Ibuprofen, Meloxicam, Diclofenac and Aspirin were calculated at energy range from 4.65 keV to 59.543 keV using the WinXCom data programme. In addition total atomic (σta), moleculer (σtm), electronic cross-section (σte), effective atomic number (Zeff), effective electron density (Neff) were calculated.