Hybrid Spectral Micro-CT: System Design, Implementation, and Preliminary Results

Bennett, James R.; Opie, Alex M. T.; Xu, Qiong; Yu, Hengyong; Walsh, Michael F.; Butler, Anthony; Butler, P.H.; Cao, Guohua; Mohs, Aaron M.; Wang, Ge

doi:10.1109/tbme.2013.2279673

Cited by 26 publications

(25 citation statements)

References 24 publications

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“…To date, various PCCT prototypes have been developed or are under development. Some silicon-strip-based PCDs (Xu et al 2012, Xu et al 2013a, 2013b) allow high photon flux, but most CdTe- and CZT-based PCDs are based on low tube current (mA) x-ray flux (Schlomka et al 2008, Shikhaliev 2008b, Iwanczyk et al 2009, Bennett et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array

et al. 2016

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This study evaluated the conventional imaging performance of a research whole-body photon-counting CT system and investigated its feasibility for imaging using clinically realistic levels of x-ray photon flux. This research system was built on the platform of a 2nd generation dual-source CT system: one source coupled to an energy integrating detector (EID) and the other coupled to a photon-counting detector (PCD). Phantom studies were conducted to measure CT number accuracy and uniformity for water, CT number energy dependency for high-Z materials, spatial resolution, noise, and contrast-to-noise ratio. The results from the EID and PCD subsystems were compared. The impact of high photon flux, such as pulse pile-up, was assessed by studying the noise-to-tube-current relationship using a neonate water phantom and high x-ray photon flux. Finally, clinical feasibility of the PCD subsystem was investigated using anthropomorphic phantoms, a cadaveric head, and a whole-body cadaver, which were scanned at dose levels equivalent to or higher than those used clinically. Phantom measurements demonstrated that the PCD subsystem provided comparable image quality to the EID subsystem, except that the PCD subsystem provided slightly better longitudinal spatial resolution and about 25% improvement in contrast-to-noise ratio for iodine. The impact of high photon flux was found to be negligible for the PCD subsystem: only subtle high-flux effects were noticed for tube currents higher than 300 mA in images of the neonate water phantom. Results of the anthropomorphic phantom and cadaver scans demonstrated comparable image quality between the EID and PCD subsystems. There were no noticeable ring, streaking, or cupping/capping artifacts in the PCD images. In addition, the PCD subsystem provided spectral information. Our experiments demonstrated that the research whole-body photon-counting CT system is capable of providing clinical image quality at clinically realistic levels of x-ray photon flux.

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Section: Introductionmentioning

confidence: 99%

Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array

et al. 2016

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“…A prevailing strategy for overcoming many of these issues is to supplement PCD projection data with projection data from a second EID detector. This hybrid data acquisition strategy has already been implemented to extend the field of view of PCD projection data to avoid truncation and to provide context for experimental PCD data [9, 12, 13, 17]. …”

Section: Introductionmentioning

confidence: 99%

Hybrid spectral CT reconstruction

Clark

Badea

2017

PLoS ONE

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Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ! 5 mg/ml and barium at concentrations ! 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral separation on the order of the energy resolution of the PCD hardware.

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“…Benefits of PCD compared to EID include reduced or fully eliminated electronic noise, improved CNR, and improved dose efficiency. [11][12][13][14][18][19][20][21][22][23] More importantly, the energy discrimination nature of the PCD enables a single-detector, single-source, and single-tubepotential multienergy imaging technique. 18,[24][25][26][27][28][29][30] Since PCDs use a direct conversion technique rather than the indirect conversion technique in EIDs, the requirement of septa between detector pixels can be avoided.…”

Section: Introductionmentioning

confidence: 99%

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

et al. 2016

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, "Dose-efficient ultrahighresolution scan mode using a photon counting detector computed tomography system," J. Med. Imag. 3(4), 043504 (2016), doi: 10.1117/1.JMI.3.4.043504. Abstract. An ultrahigh-resolution (UHR) data collection mode was enabled on a whole-body, research photon counting detector (PCD) computed tomography system. In this mode, 64 rows of 0.45 mm × 0.45 mm detector pixels were used, which corresponded to a pixel size of 0.25 mm × 0.25 mm at the isocenter. Spatial resolution and image noise were quantitatively assessed for the UHR PCD scan mode, as well as for a commercially available UHR scan mode that uses an energy-integrating detector (EID) and a set of comb filters to decrease the effective detector size. Images of an anthropomorphic lung phantom, cadaveric swine lung, swine heart specimen, and cadaveric human temporal bone were qualitatively assessed. Nearly equivalent spatial resolution was demonstrated by the modulation transfer function measurements: 15.3 and 20.3 lp∕cm spatial frequencies were achieved at 10% and 2% modulation, respectively, for the PCD system and 14.2 and 18.6 lp∕cm for the EID system. Noise was 29% lower in the PCD UHR images compared to the EID UHR images, representing a potential dose savings of 50% for equivalent image noise. PCD UHR images from the anthropomorphic phantom and cadaveric specimens showed clear delineation of small structures.

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Hybrid Spectral Micro-CT: System Design, Implementation, and Preliminary Results

Cited by 26 publications

References 24 publications

Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array

Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array

Hybrid spectral CT reconstruction

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

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