Photon Counting Detectors Viewed as Nonlinear, Shift-Variant Systems
Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski in Spectral, Photon Counting Computed Tomography, 2020
X-ray detectors are tools used in x-ray imaging. As such, photon counting detectors must not only be compared to and benchmarked against each other. Instead, all competing technologies must be considered in a fair and unbiased comparison to assess whether photon counting brings a true benefit. Energy integrating detectors, in fact, comprise a wide range of technologies and commercial designs. While those flat panel detectors that employ thin film transistors on amorphous silicon have been the hallmark of modern cone beam x-ray imaging, this technology is now being replaced by one relying on CMOS electronics more and more. CMOS technology is also the basis of photon counting detectors and enables integrating complex and low-noise signal amplification electronics into each individual pixel. Consequently, the x-ray images produced by CMOS-based energy integrating detectors are known to show very little readout noise or dark current. Unlike photon counting detectors, energy integrating detection concepts based on CMOS technology do not suffer from the multiple counting of events, or their complete loss. In addition, they are a lot cheaper to fabricate in comparison to photon counting detectors (at the time of writing). It will therefore be very interesting to see which concept will prevail, and it may well be that different applications will require different kinds of detectors even in the distant future. Either way, there will be an abundance of questions to study and comparisons to make, and the science of x-ray detection is very likely to remain an exciting field for many years to come.
Tests and procedures
Sarah Bekaert in Women's Health, 2018
The X-ray detector can calculate the strength of the X-ray beam that has passed through the patient’s body (the denser the tissue, the less X-rays pass through). The detector then feeds this information into a computer. Different types of tissue with different densities show up on the computer monitor as a picture with different colours or shades of grey. Thus in effect the computer creates a picture of a thin ‘slice’ (cross section) of the patient’s body.
Design and Assessment Principles of Semiconductor Flat-Panel Detector-Based X-Ray Micro-CT Systems for Small-Animal Imaging
Iniewski Krzysztof in Integrated Microsystems, 2017
Modern designs make use of the so-called flat-panel x-ray detectors (semiconductor-based light detector matrices coupled to scintillator screens [20] or direct conversion semiconductor detectors), due to their high resolution (equal to or better than that achieved by CCDs) and image quality, combined with a compact design and low weight that simplifies integration in the rotating gantry. Their main drawback is that most of them are slower than CCDs.
An outlook on using serial femtosecond crystallography in drug discovery
Published in Expert Opinion on Drug Discovery, 2019
Alexey Mishin, Anastasiia Gusach, Aleksandra Luginina, Egor Marin, Valentin Borshchevskiy, Vadim Cherezov
In this section, we will describe major developments and state-of-the-art related to sample preparation, data collection, and data processing for an SFX experiment. The layout of a typical SFX beamline includes beam focusing and conditioning modules, a sample chamber with an integrated sample delivery system, and an X-ray detector (Figure 2). To reduce background scattering due to a strong XFEL beam, the sample chamber is kept under vacuum or filled with helium at atmospheric pressure. Helium chambers offer simplicity and flexibility in exchange for a moderately increased background. They also can accommodate a broader variety of sample delivery methods along with optical laser systems for time-resolved pump-probe experiments, as well as allow for diverse sample environments such as pressure, temperature, humidity, etc. X-ray detectors for SFX have special requirements due to an extremely large number of photons arriving at the detector within a few femtosecond pulse duration and a high pulse repetition rates at modern XFELs. Finally, SFX data processing requires the development of special software for assembling a dataset using static diffraction snapshots captured from thousands of crystals in random orientations.
Distribution of the C statistic with applications to the sample mean of Poisson data
Published in Journal of Applied Statistics, 2020
PG 1116+215 is a quasar located at a distance from Earth of approximately 2.5 billion light years and it has been observed by the Chandra X-ray satellite several times [6,7]. The X-ray detectors used by Chandra collect individual photons from the source and neighboring areas in the sky, and measure each photon's wavelength. The photons are distributed in data points according to their wavelengths, and this distribution is usually referred to as the source's spectrum.
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