1-μm spatial resolution in silicon photon-counting CT detectors

Sundberg, Christel; Persson, Mats; Wikner, J. Jacob; Danielsson, Mats

doi:10.1117/1.jmi.8.6.063501

Cited by 10 publications

(26 citation statements)

References 27 publications

(45 reference statements)

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“…However, regarding interaction positions in the x direction, we have previously presented a method to obtain 1-μm resolution for low-energy interactions which, if desired, could enable using different template curves based on the interaction position in the x direction. 9 The count-rate performance of the presented detector geometry is expected to be high. We have previously presented detector prototypes with a count-rate performance that is linear up to 90 Mcps∕mm 2 .…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2023

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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 μm 2 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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2023

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“…Fig. 3 D ) could be achieved with subpixel localization schemes with photon-counting detectors reaching few-μm spatial resolution ( 39 ). Recently demonstrated stretchable high-resolution scintillators ( 40 ) are also promising alternatives to conventional flat-panel or upcoming photon-counting detectors for large field-of-view applications such as chest radiography.…”

Section: Discussionmentioning

confidence: 99%

Phase-contrast virtual chest radiography

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et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Respiratory X-ray imaging enhanced by phase contrast has shown improved airway visualization in animal models. Limitations in current X-ray technology have nevertheless hindered clinical translation, leaving the potential clinical impact an open question. Here, we explore phase-contrast chest radiography in a realistic in silico framework. Specifically, we use preprocessed virtual patients to generate in silico chest radiographs by Fresnel-diffraction simulations of X-ray wave propagation. Following a reader study conducted with clinical radiologists, we predict that phase-contrast edge enhancement will have a negligible impact on improving solitary pulmonary nodule detection (6 to 20 mm). However, edge enhancement of bronchial walls visualizes small airways (< 2 mm), which are invisible in conventional radiography. Our results show that phase-contrast chest radiography could play a future role in observing small-airway obstruction (e.g., relevant for asthma or early-stage chronic obstructive pulmonary disease), which cannot be directly visualized using current clinical methods, thereby motivating the experimental development needed for clinical translation. Finally, we discuss quantitative requirements on distances and X-ray source/detector specifications for clinical implementation of phase-contrast chest radiography.

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Section: Methodsmentioning

confidence: 99%

“…In this work, the assumed spatial resolution corresponds to a narrow strip design presented in our previous work, however, apart from the spatial resolution, no further assumptions were made based on that work. 9 To improve the robustness of the estimation using Monte Carlo integration, all delta functions with respect to energy in the likelihood expressions were replaced with Gaussian counterparts. These Gaussian functions were chosen as to have a mean corresponding to the total deposited energy and the same standard deviation σ E ¼ 0.5 keV as for the added errors in energy in the Monte Carlo integration.…”

Section: Likelihood Function Implementationmentioning

confidence: 99%

“…This introduces the possibility of either reducing the amount of tungsten shielding that is used or removing it entirely to achieve a larger active area and to allow secondary interactions that could improve the detector performance if identified correctly. We have previously presented a method to obtain

resolution in a silicon detector for CT. 9 In this work, we propose using a detector with similar spatial resolution to estimate the incident photon energy and position using a maximum likelihood approach based on Compton scattering. We also propose an alternative method in which the incident photon energy is estimated without taking spatial information into account.…”

Section: Introductionmentioning

confidence: 99%

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Compton coincidence in silicon photon-counting CT detectors

2022

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Purpose: Compton interactions amount to a significant fraction of the registered counts in a silicon detector. In a Compton interaction, only a part of the photon energy is deposited and a single incident photon can result in multiple counts unless tungsten shielding is used. Deep silicon has proved to be a competitive material for photon-counting CT detectors, but to improve the performance further, one possibility is to use coincidence techniques to identify Compton-scattered photons and reconstruct their incident energies.Approach: In a detector with no tungsten shielding, incident photons can interact through a series of interactions. Based on the position and energy of each interaction, probability-based methods can be used to estimate the incident photon energy. Here, we present a maximum likelihood estimation framework along with an alternative method to estimate the incident photon energy and position in a silicon detector.Results: Assuming one incident photon per time frame, we show that the incident photon energy can be estimated with a mean error of −0.07 AE 0.03 keV and an RMS error of 3.36 AE 0.02 keV for a realistic case in which we assume a detector with limited energy and spatial resolution. The interaction position was estimated with a mean error of −2 AE 11 μm in x direction and 7 AE 11 μm in y direction. Corresponding RMS errors of 1.09 AE 0.01 and 1.10 AE 0.01 mm were achieved in x and y, respectively. Conclusions:The presented results show the potential of using probability-based methods to improve the performance of silicon detectors for CT.

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1-μm spatial resolution in silicon photon-counting CT detectors

Cited by 10 publications

References 27 publications

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

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

Phase-contrast virtual chest radiography

Compton coincidence in silicon photon-counting CT detectors

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