Timing resolution in double-sided silicon photon-counting computed tomography detectors

Christel Sundberg; Mats U. Persson; Jacob Wikner; Mats Danielsson

doi:10.1117/1.JMI.10.2.023502

23 March 2023 Timing resolution in double-sided silicon photon-counting computed tomography detectors

Christel Sundberg, Mats U. Persson, Jacob Wikner, Mats Danielsson

Author Affiliations +

Journal of Medical Imaging, Vol. 10, Issue 2, 023502 (March 2023). https://doi.org/10.1117/1.JMI.10.2.023502

Abstract

Purpose

Our purpose is to investigate the timing resolution in edge-on silicon strip detectors for photon-counting spectral computed tomography. Today, the timing for detection of individual x-rays is not measured, but in the future, timing information can be valuable to accurately reconstruct the interactions caused by each primary photon.

Approach

We assume a pixel size of 12 × 500 μm² and a detector with double-sided readout with low-noise CMOS electronics for pulse processing for every pixel on each side. Due to the electrode width in relation to the wafer thickness, the induced current signals are largely dominated by charge movement close to the collecting electrodes. By employing double-sided readout electrodes, at least two signals are generated for each interaction. By comparing the timing of the induced current pulses, the time of the interaction can be determined and used to identify interactions that originate from the same incident photon. Using a Monte Carlo simulation of photon interactions in combination with a charge transport model, we evaluate the performance of estimating the time of the interaction for different interaction positions.

Results

Our simulations indicate that a time resolution of 1 ns can be achieved with a noise level of 0.5 keV. In a detector with no electronic noise, the corresponding time resolution is ∼0.1 ns.

Conclusions

Time resolution in edge-on silicon strip CT detectors can potentially be used to increase the signal-to-noise-ratio and energy resolution by helping in identifying Compton scattered photons in the detector.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Citation Download Citation

Christel Sundberg, Mats U. Persson, Jacob Wikner, and Mats Danielsson "Timing resolution in double-sided silicon photon-counting computed tomography detectors," Journal of Medical Imaging 10(2), 023502 (23 March 2023). https://doi.org/10.1117/1.JMI.10.2.023502

Received: 7 February 2022; Accepted: 22 February 2023; Published: 23 March 2023

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