Secondary X-ray imaging: an alternative approach to angiography and other applications

Csonka, Paul L.

doi:10.1016/s0168-9002(99)00260-0

Cited by 6 publications

(10 citation statements)

References 13 publications

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“…The cross prior term already has a convenient quadratic, separable form and thus the entire surrogate objective function is separable and an update equation can be readily obtained for each image pixel. The result obtained in Appendix B is that given the estimate of the image vector after the th iteration, the next estimate is obtained by solving the quadratic equation (16) where (17) (18) and (19) where (20) and…”

Section: Alternating Maximization Strategymentioning

confidence: 99%

“…Zinc X-rays, for example, are only 8.6 keV, and have a attenuation length of approximately 1 mm in tissue. Nontomographic approaches for using fluorescence X-rays for medical imaging in humans have been explored by Csonka [20], [21]. Finally, the possibility of performing simultaneous transmission CT and XFCT using exogenous highmaterials such as gadolinium and gold on a conventional CT scanner has been explored by von Busch et al [22].…”

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Monotonic penalized-likelihood image reconstruction for X-ray fluorescence computed tomography

Rivière

Vargas

2006

IEEE Trans. Med. Imaging

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In this paper, we derive a monotonic penalized-likelihood algorithm for image reconstruction in X-ray fluorescence computed tomography (XFCT) when the attenuation maps at the energies of the fluorescence X-rays are unknown. In XFCT, a sample is irradiated with pencil beams of monochromatic synchrotron radiation that stimulate the emission of fluorescence X-rays from atoms of elements whose K- or L-edges lie below the energy of the stimulating beam. Scanning and rotating the object through the beam allows for acquisition of a tomographic dataset that can be used to reconstruct images of the distribution of the elements in question. XFCT is a stimulated emission tomography modality, and it is thus necessary to correct for attenuation of the incident and fluorescence photons. The attenuation map is, however, generally known only at the stimulating beam energy and not at the energies of the various fluorescence X-rays of interest. We have developed a penalized-likelihood image reconstruction strategy for this problem. The approach alternates between updating the distribution of a given element and updating the attenuation map for that element's fluorescence X-rays. The approach is guaranteed to increase the penalized likelihood at each iteration. Because the joint objective function is not necessarily concave, the approach may drive the solution to a local maximum. To encourage the algorithm to seek out a reasonable local maximum, we include in the objective function a prior that encourages a relationship, based on physical considerations, between the fluorescence attenuation map and the distribution of the element being reconstructed.

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Section: Alternating Maximization Strategymentioning

confidence: 99%

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confidence: 99%

Monotonic penalized-likelihood image reconstruction for X-ray fluorescence computed tomography

Rivière

Vargas

2006

IEEE Trans. Med. Imaging

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“…The production of certain medical quality images e.g. for human angiography by this method requires one to approach or surpass the performance limits of present day x-ray sources "Secondary X-ray Imaging" (SXI) is an alternative imaging approach, proposed [8,9,10] in an attempt to circumvent these difficulties. A thin primary x-ray beam is rastered through the target pixel by pixel, and for each position of this beam the emitted secondary x-ray intensity is recorded.…”

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confidence: 99%

“…It can accept a broad energy band of primary x-rays, at least one, or two orders of magnitude higher than is needed for the KES technique [8]. It has the potential of requiring significantly less primary beam intensity.…”

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Calculated performance of broadband secondary x-ray imaging (SXI) based on fourth generation sources and optics and its potential application to human angiography

Csonka¹

2005

SPIE Proceedings

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A calculation was carried out to evaluate the capabilities of SecondaryX-ray Imaging (SXI), applied to human angiography. A primary photon pencil beam is rastered through the human heart, in two directions perpendicular to the primary photon beam. The signal is generated by fluorescent photons from a contrast agent, registered by a wide angle detector. One result is clearer images and a reduction of shadowing by obstructions inside the body. Sharp imaging is compatible with locally quantitative measurements, and also with pixel by pixel elemental analysis. The detector need not be position sensitive. Most of the primary beam will be scattered before they reach the target, but unscattered primary beam remains well focused. To discriminate against scattered background, the photons have to pass through a position/momentum selector, a W -Hf absorber shield, and a time window. The calcualation gives the approximate energy spectrum for the scattered photons, for the photons passing through the position/momentum selector, and for those at thefar side of the absorber shield. The last two are evaluated for time windows between 1000 and 167 ps. The surviving background causes relative image intensity fluctuations of the order of a percent. The primary beam intensity required for SXI is comparable or less than the intensity needed for Iodine K-edge subtraction (KES) imaging, but for SXI the primary photon energy spread may be one or two orders higher than what is needed for KES. Therefore, the requirements on the primary photon source an be relaxed. With an undulator as source, monochromatization may not be needed. That would further reduce the cost of the photon source, which may be a small low energy electron ring.

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Secondary X-ray imaging: an alternative approach to angiography and other applications

Cited by 6 publications

References 13 publications

Monotonic penalized-likelihood image reconstruction for X-ray fluorescence computed tomography

Monotonic penalized-likelihood image reconstruction for X-ray fluorescence computed tomography

Calculated performance of broadband secondary x-ray imaging (SXI) based on fourth generation sources and optics and its potential application to human angiography

Radiation background and beam quality in secondary X-ray imaging for human angiography with Au as contrast agent

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