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Photon-counting mammography was introduced commercially in 2003 and was the first widely available application of photon-counting detector technology in medical x-ray imaging. [1] Photon-counting mammography improves dose efficiency compared to conventional technologies, [ 2 ] and enables spectral imaging .
Dual-energy imaging, i.e. imaging at two energy levels, is a special case of spectral imaging and is still the most widely used terminology, but the terms "spectral imaging" and "spectral CT" have been coined to acknowledge the fact that photon-counting detectors have the potential for measurements at a larger number of energy levels. [2] [3]
Medipix-2 MXR is an improved version of Medipix-2 device with better temperature stability, pixel counter overflow protection, increased radiation hardness and many other improvements. Timepix is device conceptually originating from Medipix-2. It adds two more modes to the pixels, in addition to counting of detected signals: Time-over-Threshold ...
[2] [3] Due to the large volumes and rates of data required (up to several hundred million photon interactions per mm 2 and second [4]) the use of PCDs in CT scanners has become feasible only with recent improvements in detector technology. As of January 2021 photon-counting CT is in use at five clinical sites.
Photon counting eliminates gain noise, where the proportionality constant between analog signal out and number of photons varies randomly. Thus, the excess noise factor of a photon-counting detector is unity, and the achievable signal-to-noise ratio for a fixed number of photons is generally higher than the same detector without photon counting.
[5] [note 1] The narrow bandgap reduces gain dispersion, resulting in a uniform response to each photon, and hence the output pulse height is proportional to the number of incident photons. VLPCs must operate at cryogenic temperatures (6–10 K). [5] They have a quantum efficiency of 85% at 565 nm [4] and a temporal resolution of several ...
photon energy: n: 1: count of photons n with energy Q p = h c/λ. [nb 2] photon flux: Φ q: count per second: s −1: T −1: photons per unit time, dn/dt with n = photon number. also called photon power: photon intensity: I: count per steradian per second sr −1 ⋅s −1: T −1: dn/dω: photon radiance: L q: count per square metre per ...
Metal K-edge spectroscopy is a spectroscopic technique used to study the electronic structures of transition metal atoms and complexes. This method measures X-ray absorption caused by the excitation of a 1s electron to valence bound states localized on the metal, which creates a characteristic absorption peak called the K-edge. The K-edge can ...