Hybrid spectral CT reconstruction.
Abstract
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.
Type
Journal articleSubject
AnimalsBarium
Calcium
Contrast Media
Iodine
Mice
Phantoms, Imaging
Photons
Radiographic Image Interpretation, Computer-Assisted
Sarcoma
Soft Tissue Neoplasms
Tomography, X-Ray Computed
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https://hdl.handle.net/10161/15758Published Version (Please cite this version)
10.1371/journal.pone.0180324Publication Info
Clark, Darin P; & Badea, Cristian T (2017). Hybrid spectral CT reconstruction. PLoS One, 12(7). pp. e0180324. 10.1371/journal.pone.0180324. Retrieved from https://hdl.handle.net/10161/15758.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Cristian Tudorel Badea
Professor in Radiology
Our lab's research focus lies primarily in developing novel quantitative imaging systems,
reconstruction algorithms and analysis methods. My major expertise is in preclinical
CT.
Currently, we are particularly interested in developing novel strategies for spectral
CT imaging using nanoparticle-based contrast agents for theranostics (i.e. therapy
and diagnostics).
We are also engaged in developin
Darin Clark
Assistant Professor in Radiology
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