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Photon Counting Detector Simulator
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, Spectral, Photon Counting Computed Tomography, 2020
Use case 2 is to study the effect of PCD pixel binning and anti-scatter grids (6). Both signals and correlated noise of adjacent PCD pixels through different water thicknesses can be computed from the normalized covariance matrix. The effect of anti-scatter grids in terms of blocking x-rays and eliminating spill-in and spill-out cross-talks between PCD pixels can be taken into account by moving the “central pixel” that receives the x-rays and accumulating the signals and noise. The effect of N × N pixel binning can be taken into account by summing the outputs of multiple pixels into one output datum.
Dental and Maxillofacial Cone Beam Computed Tomography
Published in Paolo Russo, Handbook of X-ray Imaging, 2017
William C. Scarfe, Christos Angelopoulos, Bruno Correa de Azevedo, Shiva Toghyani, Allan G. Farman
The spatial resolution of maxillofacial CBCT systems is primarily a function of sensor nominal pixel size and fill factor; however, factors such as beam projection geometry, patient X-ray scatter, sensor motion blur, X-ray generator focal spot size, number of basis images, and reconstruction algorithm all contribute to the final maximum achievable resolution. Most manufacturers provide options for varying resolution of CBCT data. However, sensors cannot, per se, be altered to change the number of pixels within the area matrix that capture X-rays. For a given projection geometry and FOV, then the acquired dataset is always acquired at the highest resolution. In some CBCT units, resolution can be increased by altering projection geometry, reducing the object to focal spot distance. Electronic pixel binning is often used to provide reconstructed images with voxel resolution less than that acquired. Pixel binning is the process of combining charge from adjacent pixels from the sensor during readout. The two primary benefits of binning are improved contrast due to an improved signal-to-noise ratio and the ability to increase frame rate, albeit at the expense of reduced spatial resolution. While higher resolution may be considered desirable for many tasks in dentistry, it should be used judiciously for procedures demanding accuracy to the level of detail of approximately the periodontal ligament space (i.e., approximately 0.2 mm or less). Images taken at high-resolution often have reduced brightness and contrast, increased noise (when displayed in thin slice thickness), and require increased reconstruction time. While increased image resolution in some maxillofacial CBCT units does not affect changes in exposure parameters, some manufacturers incorporate reduced-dose exposure protocols for low-resolution settings.
Interference Microscopy for Surface Structure Analysis
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
Microscopes for quantitative microscopy employ a two-dimensional array camera for electronic image capture and computer processing. Areal measuring systems may use conventional cameras of the CCD or CMOS type, with a format ranging from 640 × 480 pixels to over 4 million pixels [43]. In addition to field size, the data acquisition speed in camera frames per second, the linearity, and quantum well size are of primary importance. Additional capabilities of interest include pixel binning for lower noise or faster acquisition speeds.
Fractal Analysis of Fluorescence Images to Assess Robustness of Reference-surface Positioning in Flame Fronts
Published in Combustion Science and Technology, 2021
Guido Troiani, Michele Marrocco
Flame front detection is performed by the acquisition of fluorescence signal emitted by OH radicals. To that end, a Nd:YAG laser beam is delivered through a tunable dye laser coupled with a second-harmonic generator crystal in order to shift the laser wavelength from nm down to nm, corresponding to the absorption line of OH. A suitable cylindrical lens expands the beam into a thick laser sheet. The resulting OH fluorescence emission is around nm and is then collected by a pixels ICCD ( pixel binning) equipped with a mm Nikon quartz lens, resulting in a map of equivalent pixels with a resolution of for each equivalent pixel. Furthermore, a narrow pass-band filter, nm wide and centered at nm, isolates the relevant spectral line.
Investigation of the roughness variation along the length of LPBF manufactured straight channels
Published in Nondestructive Testing and Evaluation, 2020
Christopher G. Klingaa, Thomas Dahmen, Sina Baier-Stegmaier, Sankhya Mohanty, Jesper H. Hattel
The X-ray CT scans were conducted using a Nikon XT H 225 ST system with a flat panel detector and a cone beam setup. The X-ray tomograms were obtained using a W filament, a 0.5 mm Sn filter, a power of 29.9 W, and a voltage of 220 kV. 1571 projections were acquired with two frames averaged per projection. An exposure time of t = 1 s was used for each projection and a voxel size of 15.9 µm was obtained with two by two pixel binning. The reconstruction was conducted with the X-Tek CT Pro 3D software (Nikon Metrology Inc.), using filtered-back projection. The acquired and reconstructed volumes were subsequently realigned and cropped in Avizo 9.2 after which each volume was exported as a stack of 500 cross-sectional images along the direction of the channel. An image stack represented a length of 500 × 15.9 µm = 7.95 mm.
Recombinant expression and characterization of yeast Mrc1, a DNA replication checkpoint mediator
Published in Preparative Biochemistry & Biotechnology, 2020
About 3 μL of aliquots were applied to a freshly glow-discharged carbon-coated 400-mesh copper-electron microscopy specimen grid, and then was preserved by staining with 0.75% (w/w) uranyl formate (UF) solution. Images were recorded at a magnification of ×62,000 on a 4096 × 4096 charge-coupled device (CCD) detector (FEI Eagle) with a Tecnai F20 electron microscope (FEI) operating at an acceleration voltage of 200 kV. Images were recorded by using low-dose procedures at ∼1.0–1.2 μm under focus. Two-fold pixel binning of the original CCD images resulted in a final pixel size of 3.01 Å per pixel. Particles were manually or automatically picked and were montaged for interactive screening.[21] Totally, 23,152 Mrc1 (287-1096AA) particles and 18,930 Mrc1 (287-1096AA)-DNA particles were picked after manual cleaning. Iterative alternating rounds of supervised multi-reference alignment and classification as well as reference-free alignment to improve the homogeneity of the image classes were run with SPIDER[22] and SPARX.[23]