Photon counting dual energy x-ray imaging at CT count rates: measurements and implications of in-pixel charge sharing correction
| Autor: | Mattias Urech, Charlotte Eriksson, Christer Ullberg, N. Weber, Alex Stewart |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Photon Pixel Physics::Instrumentation and Detectors business.industry Astrophysics::High Energy Astrophysical Phenomena Detector Radiant energy Flux 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Photon counting Charge sharing 010309 optics Optics 0103 physical sciences 0210 nano-technology business Energy (signal processing) |
| Zdroj: | Medical Imaging 2018: Physics of Medical Imaging. |
| Popis: | In photon counting detectors with small pixels, charge sharing has a significant effect on the spectral response and on the image quality. A charge can be shared between pixels for two main reasons; a photon can be physically converted at the edges or corners in-between pixels and K-edge X-ray fluorescence in the converter can redistribute radiative energy to other pixels nearby. A potential drawback of photon counting detectors is the limited count rate due to pulse pileup. Pulse-pileup also distorts the recorded energy of the X-rays as pulse pileup shifts the spectra towards higher energy. With active charge sharing correction the signals from neighboring pixels contribute to dead-time of the pixel and therefore the pulse-pileup at the same input flux is increased. We compare the measured performance of an XCounter dual energy photon counting CdTe detector with 100μm pixels with and without charge sharing correction up to an input flux of 3.5*108 photons/mm2/s and show that there is a benefit to using the charge sharing correction up to 2.5*108 photons/mm2 /s. Spectra are recorded from Am241 and Cd109 at low flux to show the energy response without pulse pileup and from a 90kVp beam at high flux. Material separation between PMMA and Aluminum is evaluated in terms of SDNR for different flux with and without charge sharing up to an input flux of 3.5*108 photons/mm2/s. |
| Databáze: | OpenAIRE |
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