PIXIE III: a very large area photon-counting CMOS pixel ASIC for sharp X-ray spectral imaging

Bellazzini, R.; Brez, A.; Spandre, G.; Minuti, M.; Pinchera, Michele; Delogu, Pasquale; Ruvo, P. L. de; Vincenzi, A.

doi:10.1088/1748-0221/10/01/c01032

Cited by 77 publications

(46 citation statements)

References 2 publications

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“…The energy bins above 35 keV were also discarded during the analysis, due to the extremely limited statistics. It should be noted, however, that the problem of charge sharing can be substantially mitigated by using a more sophisticated read-out scheme [34].…”

Section: Methodsmentioning

confidence: 99%

Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources

Endrizzi¹,

Vittoria²,

Kallon³

et al. 2015

Opt. Express

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Compatibility with polychromatic radiation is an important requirement for an imaging system using conventional rotating anode X-ray sources. With a commercially available energy-resolving single-photon-counting detector we investigated how broadband radiation affects the performance of a multi-modal edge-illumination phase-contrast imaging system. The effect of X-ray energy on phase retrieval is presented, and the achromaticity of the method is experimentally demonstrated. Comparison with simulated measurements integrating over the energy spectrum shows that there is no significant loss of image quality due to the use of polychromatic radiation. This means that, to a good approximation, the imaging system exploits radiation in the same way at all energies typically used in hard-X-ray imaging.

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Section: Methodsmentioning

confidence: 99%

Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources

Endrizzi¹,

Vittoria²,

Kallon³

et al. 2015

Opt. Express

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“…In Pixie-III this problem is mitigated by summing up the signals of neighbouring pixels, to correctly evaluate the total energy of any event involving up to 4 pixels. This hardware solution improves the energy resolution 11 , and this is beneficial for spectral imaging applications. Pixie-III is a 0.16 mm CMOS ASIC organized as a 512 × 402 matrix of square pixels with 62 m pitch resulting in an active area of 31.7 × 24.9 mm 2 .…”

Section: Sourcementioning

confidence: 99%

Edge-subtraction X-ray ptychographic imaging with pink beam synchrotron radiation and a single photon-counting detector

Brun

Trapani

Batey

et al. 2020

Sci Rep

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We present here a new method of performing X-ray edge-subtraction ptychographic imaging by combining multiple harmonics from an undulator synchtrotron source and an energy discriminating photon counting detector. Conventionally, monochromatic far-field X-ray ptychography is used to perform edge subtraction through the use of multiple monochromatic energy scans to obtain spectral information for a variety of applications. Here, we use directly the undulator spectrum from a synchrotron source, selecting two separate harmonics post sample using the Pixirad-1/Pixie-III detector. The result is two monochromatic images, above and below an absorption edge of interest. The proposed method is applied to obtain Au L-edge subtraction imaging of a Au-Ni grid test sample. The Au L-edge subtraction is particularly relevant for the identification of gold nanoparticles for biomedical applications. Switching the energy scan mechanism from a mechanical monochromator to an electronic detector threshold allows for faster spectral data collection with improved stability.

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“…Some PCD designs aim at event‐based real‐time processing that corrects for the charge sharing for each event . The key technology is a sophisticated inter‐pixel communication to identify coincident events and correct charge sharing for each event in real time …”

Section: Introductionmentioning

confidence: 99%

Multi‐energy inter‐pixel coincidence counters for charge sharing correction and compensation in photon counting detectors

Taguchi

2020

Medical Physics

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Purpose: Smaller pixel sizes of x-ray photon counting detectors (PCDs) are advantageous for count rate capabilities but disadvantageous for charge sharing. With charge sharing, the energy of an x-ray photon may be split and one photon may produce two or more counts at adjacent pixels, both at lower energies than the incident energy. This "double-counting" increases noise variance and degrades the spectral response. Overall, it has a significantly negative impact on the performance of PCD-based computed tomography (CT). Charge sharing is induced by the detection physics and occurs regardless of count rates; thus, it is impossible to avoid. We propose in this paper a method that has a potential to address both noise and bias added by charge sharing. Methods: We propose applying a multi-energy inter-pixel coincidence counter (MEICC) technique, which uses energy-dependent coincidence counters, keeps the book of charge sharing events during data acquisition, and provides the exact number of charge sharing occurrences, which can be used to either correct or compensate for them after the acquisition is completed. MEICC does not interfere with the primary counting process; therefore, PCDs with MEICC will remain as fast as those without MEICC. MEICC can be implemented using current electronics technology because its inter-pixel coincidence counters used to handle digital data are rather simple. We evaluated Cram er-Rao lower bound (CRLB) of PCDs with and without MEICC using a Monte Carlo simulation. Results: When the number of energy windows was four or larger and eight neighboring pixels were used, the CRLBs of 225-µm PCD with MEICC normalized by those of the current PCD with the same number of windows were 0.361-0.383 for water density images of two basis functions, which was only 5.7-16.4% worse than those of a PCD without charge sharing (which were at 0.329-0.358). In contrast, the normalized CRLBs of the PCD with one coincidence counter were 0.466-0.499, which were 37.3-45.6% worse than the PCD without charge sharing. The use of eight neighboring pixels provided~10% better CRLB values than four neighboring pixels for MEICC. With four energy windows, decreasing the number of coincidence counters from 16 to 9 only slightly increased the CRLB from 0.255 to 0.269 (which corresponded to as little as a 5.5% change). The normalized CRLBs of MEICC for K-edge imaging (gold) were 0.295-0.426, while those of the one coincidence counter were 0.926-0.959 and the ideal PCDs were 0.126-0.146. Conclusions:The proposed MEICC provides spectral information that can be used to address charge sharing problems in PCDs and is expected to satisfy the requirements for clinical x-ray CT. MEICC is very effective, especially for K-edge imaging, which requires accurate spectral information.

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PIXIE III: a very large area photon-counting CMOS pixel ASIC for sharp X-ray spectral imaging

Cited by 77 publications

References 2 publications

Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources

Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources

Edge-subtraction X-ray ptychographic imaging with pink beam synchrotron radiation and a single photon-counting detector

Multi‐energy inter‐pixel coincidence counters for charge sharing correction and compensation in photon counting detectors

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