Image reconstruction: Part 1 – understanding filtered back projection, noise and image acquisition

Schofield, Richard S.; King, Laurence; Tayal, Upasana; Castellano, Isabel; Stirrup, James; Pontana, François; Earls, James P.; Nicol, Edward

doi:10.1016/j.jcct.2019.04.008

Cited by 60 publications

(38 citation statements)

References 12 publications

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“…Specimen CB5 was imaged once again at 4× post-mechanics under the same conditions to explore residual strain via DVC. All datasets were reconstructed using standard filtered back projection [41].…”

Section: Xct Image Post-processing and Synthetic Deformationmentioning

confidence: 99%

Full-Field Strain Uncertainties and Residuals at the Cartilage-Bone Interface in Unstained Tissues Using Propagation-Based Phase-Contrast XCT and Digital Volume Correlation

et al. 2020

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A deeper understanding of the cartilage-bone mechanics is fundamental to unravel onset and progression of osteoarthritis, enabling better diagnosis and treatment. The aim of this study is therefore to explore the capability of X-ray computed (XCT) phase-contrast imaging in a lab-based system to enable digital volume correlation (DVC) measurements of unstained cartilage-bone plugs from healthy adult bovines. DVC strain uncertainties were computed for both articular cartilage and mineralized tissue (calcified cartilage and subchondral bone) in the specimens at increasing propagation distances, ranging from absorption up to four times (4× such effective distance. In addition, a process of dehydration and rehydration was proposed to improve feature recognition in XCT of articular cartilage and mechanical properties of this tissue during the process were assessed via micromechanical probing (indentation), which was also used to determine the effect of long X-ray exposure. Finally, full-field strain from DVC was computed to quantify residual strain distribution at the cartilage-bone interface following unconfined compression test (ex situ). It was found that enhanced gray-scale feature recognition at the cartilage-bone interface was achieved using phase-contrast, resulting in reduced DVC strain uncertainties compared to absorption. Residual strains up to ~7000 µε in the articular cartilage were transferred to subchondral bone via the calcified cartilage and micromechanics revealed the predominant effect of long phase-contrast X-ray exposure in reducing both stiffness and hardness of the articular cartilage. The results of this study will pave the way for further development and refinement of the techniques, improving XCT-based strain measurements in cartilage-bone and other soft-hard tissue interfaces.

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Section: Xct Image Post-processing and Synthetic Deformationmentioning

confidence: 99%

Full-Field Strain Uncertainties and Residuals at the Cartilage-Bone Interface in Unstained Tissues Using Propagation-Based Phase-Contrast XCT and Digital Volume Correlation

et al. 2020

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“…The image reconstruction techniques are known to affect image quality. Filtered back projection (FBP) has been the standard reconstruction algorithm since the invention of CT 50 years ago but has been known to produce images with greater noise than more recent techniques [27]. Iterative reconstruction (IR) is a newer and more computationally intense method which can typically produce images of better quality at lower radiation dose than FBP [28,29].…”

Section: Discussionmentioning

confidence: 99%

The effect of scan and patient parameters on the diagnostic performance of AI for detecting coronary stenosis on coronary CT angiography

et al. 2022

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…However, these mentioned methods require an accurate background velocity to perform accurate imaging. In recent years, to enhance the GPR detection capability, scholars have proposed imaging methods, such as diffraction tomography (DT) [53,54], range migration (RM) [43,55], and back projection (BP) [56,57].…”

Section: Gpr Profile Reconstructionmentioning

confidence: 99%

Recent Advances in the GPR Detection of Grouting Defects behind Shield Tunnel Segments

et al. 2021

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Injecting grout into the gaps between tunnel shield segments and surrounding rocks can reduce ground subsidence and prevent ground water penetration. However, insufficient grouting and grouting defects may cause serious geological disasters. Ground penetrating radar (GPR) is widely used as a nondestructive testing (NDT) method to evaluate grouting quality and determine the existence of defects. This paper provides an overview of GPR applications for grouting defect detection behind tunnel shield segments. State-of-the-art methodologies, field cases, experimental tests and signal processing methods are discussed. The reported field cases and model test results show that GPR can detect grouting defects behind shield tunnel segments by identifying reflected waves. However, some subsequent problems still exist, including the interference of steel bars and small differences in the dielectric constants among media. Recent studies have focused on enhancing the signal-to-noise ratio and imaging methods. Advanced GPR signal processing methods, including full waveform inversion and machine learning methods, are promising for detecting imaging defects. Additionally, we conduct a preliminary experiment to investigate environmental noise, antenna configuration and coupling condition influences. Some promising topics, including multichannel configuration, rapid evaluation methods, elastic wave method scanning equipment for evaluating grout quality and comprehensive NDT methods, are recommended for future studies.

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Image reconstruction: Part 1 – understanding filtered back projection, noise and image acquisition

Cited by 60 publications

References 12 publications

Full-Field Strain Uncertainties and Residuals at the Cartilage-Bone Interface in Unstained Tissues Using Propagation-Based Phase-Contrast XCT and Digital Volume Correlation

Full-Field Strain Uncertainties and Residuals at the Cartilage-Bone Interface in Unstained Tissues Using Propagation-Based Phase-Contrast XCT and Digital Volume Correlation

The effect of scan and patient parameters on the diagnostic performance of AI for detecting coronary stenosis on coronary CT angiography

Recent Advances in the GPR Detection of Grouting Defects behind Shield Tunnel Segments

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