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Photon Counting Detectors Viewed as Nonlinear, Shift-Variant Systems
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, 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.
X-Ray Diffraction
Published in Rui Yang, Analytical Methods for Polymer Characterization, 2018
The x-ray detector converts the incoming x-rays into electric signals. The intensity of these signals is proportional to the intensity of x-rays. Proportional counters, scintillation counters, and semiconductor detectors are often used as detectors. State of the art semiconductor detectors have the best resolution [2].
Medical Imaging
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
James T. Dobbins III, Sean M. Hames, Bruce H. Hasegawa, Timothy R. DeGrado, James A. Zagzebski, Richard Frayne
X-ray imaging requires an x-ray-generating apparatus (tube, high-voltage supply, and controls) and an appropriate x-ray detector. Typical x-ray detectors include photographic film (almost always used in concert with a fluorescent screen), image intensifiers, computed radiography phosphor plates, and newer dedicated digital detectors.
A low-noise current-sensitive preamplifier for X-ray computed tomography with applying a charge-sensitive preamplifier
Published in Journal of Nuclear Science and Technology, 2021
In the pulse measurement, each X-ray photon entering to an X-ray detector induces an electric pulse by the movement of charge carriers (i.e. electrons and holes if a detector is composed of a semiconductor). These pulses are measured by a charge-sensitive preamplifier as step voltages with exponential decay induced in the feedback capacitance of it [1]. Each step voltage is fed to a spectroscopy amplifier and is integrated for a time period defined as a shaping time as shown in Figure 1(a). The spectroscopy amplifier produces a pulse which height is proportional to the energy deposited by the X-ray photon. In short, the pulse measurement gives the voltage pulse which is proportional to the energy of an X-ray photon.