The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have developed a technique for calibrating the energy response of individual pixels using X-ray fluorescence generated by metallic targets directly irradiated with polychromatic X-rays, and additionally γ-rays from (241)Am. This technique was used to measure the energy response of individual pixels in CdTe-Medipix3RX by characterizing noise performance, threshold dispersion, gain variation and spectral resolution. The comparison of these two techniques shows the energy difference of 1 keV at 59.5 keV which is less than the spectral resolution of the detector (full-width at half-maximum of 8 keV at 59.5 keV). Both techniques can be used as quality control tools in a pre-clinical multi-energy CT scanner using spectral X-ray detectors.
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http://dx.doi.org/10.1109/TMI.2014.2337881 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
January 2025
Institute of Chemistry, Military University of Technology, Kaliskiego 2, PL-00908 Warsaw, Poland.
Molecular arrangement in the chiral smectic phases of the glassforming (S)-4'-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate is investigated by X-ray diffraction. An increased correlation length of the positional short-range order in the supercooled state agrees with the previous assumption of the hexatic smectic phase. However, the registered X-ray diffraction patterns are not typical for the hexatic phases.
View Article and Find Full Text PDFChem Biodivers
January 2025
Guizhou Medical University, School of Pharmaceutical Sciences, University Town, Gui'an New District, 550025, Guiyang, CHINA.
An unrevealed dihydroflavone-monoterpene conjugate (1), two unrevealed kavalactones (2-3, including one with an uncommon side chain), and thirteen previously identified compounds (4-16) were extracted from Alpinia katsumadai Hayata. seeds. The two-dimension structures of the new compounds were authenticated utilizing HRESIMS as well as NMR spectral analysis, while their absolute chiral configurations were ascertained either by correlating the experimental and simulated values of electronic circular dichroism (ECD) patterns or conducting X-ray diffraction experiments.
View Article and Find Full Text PDFTransl Vis Sci Technol
January 2025
Department of Ophthalmology, University Hospital Bonn, Bonn, Germany.
Purpose: To compare a novel high-resolution optical coherence tomography (OCT) with improved axial resolution (High-Res OCT) with conventional spectral-domain OCT (SD-OCT) with regard to their capacity to characterize the disorganization of the retinal inner layers (DRIL) in diabetic maculopathy.
Methods: Diabetic patients underwent multimodal retinal imaging (SD-OCT, High-Res OCT, and color fundus photography). Best-corrected visual acuity and diabetes characteristics were recorded.
Inorg Chem
January 2025
Institute of Low Temperature and Structure Research, Polish Academy of Science, ul. Okólna 2, Wrocław 50-422, Poland.
Research is ongoing to develop new phosphors capable of emitting light across a broad spectrum, ranging from the ultraviolet (UV) to the infrared region, with potential applications in diverse fields. Using the method of solid-state reactions, a series of LiBaF:Pr phosphors were obtained, and their luminescent properties in the UV-visible range were studied. The photon cascade emission (PCE) phenomenon has been observed under excitation of the 4f5d bands of Pr.
View Article and Find Full Text PDFAnal Chim Acta
February 2025
Institute of Environmental Science, Shanxi University, Taiyuan 030006, China.
Hypochlorous acid (HClO) is a well-known inflammatory signaling molecule, while lipid droplets (LDs) are dynamic organelles closely related to inflammation. Using organic small-molecule fluorescence imaging technology to target LDs for precise monitoring of HClO is one of the most effective methods for diagnosing inflammation-related diseases. A thorough investigation of how probes detect biological markers and the influencing factors can aid in the design of probe molecules, the selection of high-performance tools, and the accuracy of disease detection.
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