Impact of polychromatic x-ray sources on helical, cone-beam computed tomography and dual-energy methods

Sidky, Emil Y.; Zou, Yu; Pan, Xiaochuan

doi:10.1088/0031-9155/49/11/012

Cited by 43 publications

(32 citation statements)

References 15 publications

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“…[39][40][41] Today, commercially available desktop XMT systems make use of polychromatic X-ray sources, which unfortunately introduce scanning artifacts such as beam hardening and loss of information due to energy averaging ( Figure 1). 42,43 Beam-hardening artifacts arise from polychromatic sources because the attenuation of the incident X-ray beam is not exponentially related to the thickness of the object, as predicted by Beer' s law. 44,45 The lower X-ray energies of the polychromatic spectrum are thus easily absorbed, while the higher energies are less attenuated.…”

Section: Two Types Of Microcomputed Tomography and Artifactsmentioning

confidence: 99%

Theory of X-ray microcomputed tomography in dental research: application for the caries research

Park

Bae

Chang

et al. 2011

J Korean Acad Conserv Dent

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Caries remains prevalent throughout modern society and is the main disease in the field of dentistry. Although studies of this disease have used diverse methodology, recently, X-ray microtomography has gained popularity as a non-destructive, 3-dimensional (3D) analytical technique, and has several advantages over the conventional methods. According to X-ray source, it is classified as monochromatic or polychromatic with the latter being more widely used due to the high cost of the monochromatic source despite some advantages. The determination of mineral density profiles based on changes in X-ray attenuation is the principle of this method and calibration and image processing procedures are needed for the better image and reproducible measurements. Using this tool, 3D reconstruction is also possible and it enables to visualize the internal structures of dental caries. With the advances in the computer technology, more diverse applications are being studied, such automated caries assessment algorithms.

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Section: Two Types Of Microcomputed Tomography and Artifactsmentioning

confidence: 99%

Theory of X-ray microcomputed tomography in dental research: application for the caries research

Park

Bae

Chang

et al. 2011

J Korean Acad Conserv Dent

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“…(Alvarez and Macovski, 1976) In practice, the basis functions can be the energy-dependent linear attenuation coefficients of two different actual or even virtual materials. (Sidky et al , 2004) The weight distributions of the two basis functions, i.e., the decomposed material images, are reconstructed from the data acquired with two different x-ray energy spectra, which can be used to calculate electron density maps or effective Z images. (Alvarez and Macovski, 1976) The original concept of DECT requires acquisition of projection data with two different x-ray energies for each projection ray.…”

Section: Introductionmentioning

confidence: 99%

Dual energy CT with one full scan and a second sparse-view scan using structure preserving iterative reconstruction (SPIR)

Wang

Zhu

2016

Phys. Med. Biol.

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Conventional dual-energy CT (DECT) reconstruction requires two full-size projection datasets with two different energy spectra. In this study, we propose an iterative algorithm to enable a new data acquisition scheme which requires one full scan and a second sparse-view scan for potential reduction in imaging dose and engineering cost of DECT. A bilateral filter is calculated as a similarity matrix from the first full-scan CT image to quantify the similarity between any two pixels, which is assumed unchanged on a second CT image since DECT scans are performed on the same object. The second CT image from reduced projections is reconstructed by an iterative algorithm which updates the image by minimizing the total variation of the difference between the image and its filtered image by the similarity matrix under data fidelity constraint. As the redundant structural information of the two CT images is contained in the similarity matrix for CT reconstruction, we refer to the algorithm as structure preserving iterative reconstruction (SPIR). The proposed method is evaluated on both digital and physical phantoms, and is compared with the filtered-backprojection (FBP) method, the conventional total-variation-regularization-based algorithm (TVR) and Prior-Image-Constrained-Compressed-Sensing (PICCS). SPIR with a second 10-view scan reduces the image noise STD by a factor of one order of magnitude with same spatial resolution as full-view FBP image. SPIR substantially improves over TVR on the reconstruction accuracy of a 10-view scan by decreasing the reconstruction error from 6.18% to 1.33%, and outperforms TVR at 50 and 20-view scans on spatial resolution with a higher frequency at the modulation transfer function value of 10% by an average factor of 4. Compared with the 20-view scan PICCS result, the SPIR image has 7 times lower noise STD with similar spatial resolution. The electron density map obtained from the SPIR-based DECT images with a second 10-view scan has an average error of less than 1%.

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“…It is equipped with two X-ray tube and detector pairs, and it simultaneously acquires projection data at two different energies. DECT images can be used for various purposes such as material differentiation, contrast enhancement of conventional CT [2], beam hardening correction [3,4], attenuation correction for single photon emission computed tomography (SPECT) or positron emission tomography (PET) [5,6], explosive detection [7], and luggage screening [8]. In addition, the electron density (ED) of scanned materials can be obtained with DECT.…”

Section: Introductionmentioning

confidence: 99%

Application of a Dual-Energy Monochromatic Xray Ct Algorithm to Polychromatic X-Ray Ct: A Feasibility Study

Chang¹,

Lee²,

Cho³

2012

Nuclear Engineering and Technology

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Impact of polychromatic x-ray sources on helical, cone-beam computed tomography and dual-energy methods

Cited by 43 publications

References 15 publications

Theory of X-ray microcomputed tomography in dental research: application for the caries research

Theory of X-ray microcomputed tomography in dental research: application for the caries research

Dual energy CT with one full scan and a second sparse-view scan using structure preserving iterative reconstruction (SPIR)

Application of a Dual-Energy Monochromatic Xray Ct Algorithm to Polychromatic X-Ray Ct: A Feasibility Study

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