Depth‐segmented detector for x‐ray absorptiometry

Stevens, Grant M.; Pelc, Norbert J.

doi:10.1118/1.598982

Cited by 10 publications

(5 citation statements)

References 18 publications

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“…In the dual-kV method, this is achieved by switching the tube voltage between the two acquisitions (Alvarez and Macovski 1976, Kelcz et al 1979, Asaga et al 1987. In the two-(or multi-) layer detector methods, the two signals are obtained simultaneously by the use of a front and a rear detector placed on top of each other (Kelcz et al 1979, Brooks and Di Chiro 1978, Sones and Barnes 1989, Barnes et al 1985, Gauntt and Barnes 1994, Alvarez 1996, Stevens andPelc 2000, Alvarez et al 2004). Both concepts are usually realized in connection with integrating detectors.…”

Section: Introductionmentioning

confidence: 99%

K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors

2007

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After passage through matter, the energy spectrum of a polychromatic beam of x-rays contains valuable information about the elemental composition of the absorber. Conventional x-ray systems or x-ray computed tomography (CT) systems, equipped with scintillator detectors operated in the integrating mode, are largely insensitive to this type of spectral information, since the detector output is proportional to the energy fluence integrated over the whole spectrum. The main purpose of this paper is to investigate to which extent energy-sensitive photon counting devices, operated in the pulse-mode, are capable of revealing quantitative information about the elemental composition of the absorber. We focus on the detection of element-specific, K-edge discontinuities of the photo-electric cross-section. To be specific, we address the question of measuring and imaging the local density of a gadolinium-based contrast agent, in the framework of a generalized dual-energy pre-processing. Our results are very promising and seem to open up new possibilities for the imaging of the distribution of elements with a high atomic number Z in the human body using x-ray attenuation measurements. To demonstrate the usefulness of the detection and the appropriate processing of the spectral information, we present simulated images of an artherosclerotic coronary vessel filled with gadolinium-based contrast agent. While conventional systems, equipped with integrating detectors, often fail to differentiate between contrast filled lumen and artherosclerotic plaque, the use of an energy-selective detection system based on the counting of individual photons reveals a strong contrast between plaque and contrast agent.

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Section: Introductionmentioning

confidence: 99%

K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors

2007

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“…Dual-energy techniques for x-ray imaging applications have received considerable interest in the past, either in the form of source-switching techniques (Alvarez and Macovski 1976, Kelcz et al 1979, Asaga et al 1987, Flohr et al 2006 or in the form of dual-, or multi-detector layer approaches (Kelcz et al 1979, Brooks and Chiro 1978, Sones and Barnes 1989, Barnes et al 1985, Gauntt and Barnes 1994, Alvarez 1996, Stevens and Pelc 2000, Alvarez et al 2004, Carmi et al 2005. In the originally proposed version of this techniques (Alvarez and Macovski 1976), the attenuation coefficient of matter is decomposed into the attenuation caused by the photoelectric effect and the attenuation caused by the Compton effect: μ( x, E) = a Ph ( x)f Ph (E) + a Co ( x)f Co (E).…”

Section: Introductionmentioning

confidence: 99%

Cramér–Rao lower bound of basis image noise in multiple-energy x-ray imaging

Roessl¹,

Herrmann²

2009

Phys. Med. Biol.

120

132

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We present an analytical method to compute the basis image noise in the context of multi-energy x-ray imaging based on the Cramér-Rao lower bound (CRLB). The proposed formalism extends the original idea of Alvarez and Macovski (1976 Phys. Med. Biol. 21 733) to estimate the noise in the photo-effect and Compton-effect basis images in the case of dual-energy imaging. It includes an arbitrary number of independent, spectrally distinct attenuation measurements and also goes beyond the two-dimensional decomposition of the attenuation, including, e.g., a contrast agent as a third basis material. To illustrate our method, we consider three simple applications. The first application is to study the influence of the exact values for the energy thresholds on the basis image noise for a binned photon-counting system. The second application relates to the same detector system as the first and is an investigation of the dependence of the basis image noise on the energy resolution of the detector system. Finally, the third application provides an example for the case of an energy-integrating detector: the aim is to optimize the front-scintillator layer thickness of a dual-crystal detector for dual-energy imaging. The CRLB is used to minimize the noise of a photo-effect/Compton-effect basis material decomposition.

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“…A second approach, in dual-source CT scanners, has two source-detector pairs mounted on a single gantry operating at two different tube voltages. A third concept, called dual-layer CT, uses two stacked detectors which simultaneously obtain two spectrally separated signals (6)(7)(8)(9)(10)(11)(12).…”

Section: Introductionmentioning

confidence: 99%

Spectral CT: a technology primer for contrast agent development

Schirra

Brendel

Anastasio

et al. 2014

Contrast Media & Molecular

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Recent developments in spectral CT systems featuring binned photon-counting detector technology have enabled an imaging concept on a pre-clinical level that has been coined K-edge imaging. This exciting concept allows the selective and quantitative imaging of contrast media by exploiting the K-edge discontinuity in the photo-electric component of X-ray absorption. An ideal application for K-edge imaging is CT imaging of target-specific and conventional contrast agents that have been designed to be spectral-CT-visible. Current limitations in detector hardware, however, result in typically high noise levels that hamper the application of K-edge imaging. In order to battle noise and assure sufficient sensitivity, the development of dedicated K-edge contrast media in combination with advanced image processing techniques is imperative. This work attempts a comprehensive overview on how the concert of dedicated contrast media, optimized data acquisition and innovative data processing techniques improve sensitivity of K-edge imaging which will foster clinical translation of the technology.

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Depth‐segmented detector for x‐ray absorptiometry

Cited by 10 publications

References 18 publications

K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors

K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors

Cramér–Rao lower bound of basis image noise in multiple-energy x-ray imaging

Spectral CT: a technology primer for contrast agent development

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