Photon counting dual energy x-ray imaging at CT count rates: measurements and implications of in-pixel charge sharing correction

Christer Ullberg; Mattias Urech; Charlotte Eriksson; Alexander Stewart; Niclas Weber

doi:10.1117/12.2293591

9 March 2018 Photon counting dual energy x-ray imaging at CT count rates: measurements and implications of in-pixel charge sharing correction

Christer Ullberg, Mattias Urech, Charlotte Eriksson, Alexander Stewart, Niclas Weber

Author Affiliations +

Proceedings Volume 10573, Medical Imaging 2018: Physics of Medical Imaging; 1057319 (2018) https://doi.org/10.1117/12.2293591
Event: SPIE Medical Imaging, 2018, Houston, Texas, United States

Abstract

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.

Conference Presentation

Citation Download Citation

Christer Ullberg, Mattias Urech, Charlotte Eriksson, Alexander Stewart, and Niclas Weber "Photon counting dual energy x-ray imaging at CT count rates: measurements and implications of in-pixel charge sharing correction", Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 1057319 (9 March 2018); https://doi.org/10.1117/12.2293591

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available