A reference sample for investigating the stability of the imaging system of x-ray computed tomography

Sun, Wenjuan; Brown, Stephen; Flay, Nadia; McCarthy, Michael; McBride, J.W.

doi:10.1088/0957-0233/27/8/085004

Cited by 17 publications

(12 citation statements)

References 7 publications

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“…SPD of magnitude within the range of 7-14 µm was observed in the most of performed scans. Such values have been described also in previously published papers [3][4][5][6][7][8]. In several datasets, however, we observed also an angular tilt of the sample.…”

Section: Discussionsupporting

confidence: 89%

“…Several papers addressing the issue of SPD in the case of high resolution CT scans have been published [3][4][5][6][7][8]. Based on these studies such effects are caused by drift of the source focal spot, thermal expansion of the setup components and mechanical inaccuracies of the sample manipulator.…”

mentioning

confidence: 99%

“…Nevertheless, other studies provide contradictory conclusions [4]. Therefore, as the most generally reliable techniques seem to be approaches using a static reference object placed into the detector field of view sideways a sample [5][6][7] or using a sparsely-sampled reference dataset [8].…”

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confidence: 99%

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X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

et al. 2017

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As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer. K: X-ray radiography and digital radiography (DR); Computerized Tomography (CT) and Computed Radiography (CR); Pixelated detectors and associated VLSI electronics 1Corresponding author.

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Section: Discussionsupporting

confidence: 89%

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confidence: 99%

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X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

et al. 2017

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“…One route to establish measurement traceability is to calibrate the measurement instrument via the metrological characteristic approach. In the field of XCT, many recent research works focused on the uncertainty evaluation of influence factors, including geometric errors [5,6], X-ray source stability [7], resolution [8], beam hardening errors and scattering errors [9,10]. However, this approach requires significant effort due to the complex systematic errors of XCT technology, hence is impractical in shop floor conditions.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of X-ray computed tomography for surface texture measurements using a prototype additively manufactured reference standard

SUN¹,

Chen²,

Giusca³

et al. 2022

eJNDT

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Additively manufactured (AM) components have complex surface textures compared with conventionally machined surfaces. There is an increasing demand from AM industry for reference standards to calibrate instruments for AM surface inspection; this is particularly important in application areas such as aerospace, where the failure of a mission-critical part can have dire safety consequences. Many AM surfaces have re-entrant features and internal surfaces and, therefore, are difficult or impossible to be accessed by conventional measurement techniques. X-ray computed tomography (XCT) is an emerging technology that is capable of measuring AM surfaces. However, the metrology framework of the technology is still under development. Recently, we have explored the calibration of XCT for surface texture evaluation using a reference standard with a unique design. The prototype surface texture reference standard has surfaces with varying roughness levels and has been designed for compatibility between profile and areal topography measuring instruments and tomography instruments. The measurement traceability of surface texture using XCT has been established for profile measurements via a calibrated contact measurement technique. This paper has further investigated the impact of sampling strategy in calibration. This preliminary study is to investigate the ability of XCT to evaluate the AM surface texture in different build orientations, where the surfaces may have limited evaluation length.

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“…This effect considerably affects the achievable spatial resolution in the reconstructed 3D volumes. Several papers dealing with the quantification of SPD effects and the means for its compensation, including the use of calibration datasets used for several subsequent scans, have been published [4,5]. Many studies treat the SPD effect as stochastic, though.…”

Section: Introductionmentioning

confidence: 99%

High resolution X-ray micro-CT imaging of fibrin scaffold using large area single photon counting detector

et al. 2018

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This paper deals with the high resolution X-ray micro-computed tomographical (micro-CT) visualization of a fibrin scaffold intended to be used during medical repairs of various types of human tissue. Due to the cellular nature of scaffolds, it is important to inspect their microstructure in high detail on a volumetric basis. In this work, we demonstrate the micro-CT measurement of a fibrin-based bone scaffold performed using a proprietarily developed tomographical scanner equipped with a large-area imaging device (LAD) composed of 10× 10 Timepix silicon pixel detectors without any gaps between the individual tiles. The fibrin scaffolds are based on organic materials, which may be reinforced by various additives to improve their mechanical characteristics, and their dimensions are generally very small (i.e. micrometer to millimeter scale). As the organic material used in fibrin scaffolds exhibits very low X-ray attenuation, low-energy X-ray radiation is desirable to achieve sufficient contrast in the projections. Moreover, a high resolution is needed to visualize the fine features in the scaffolds. Here, conventional scintillation detectors suffer two problems that make the aforementioned LAD superior for the imaging of the investigated scaffolds: a wide point-spread function and low sensitivity at low energies. Despite the high LAD sensitivity to low-energy photons, it was necessary to apply several correction procedures to achieve the highest possible resolution. Here, a computational procedure was developed to compensate for the drift of the tube's focal spot, geometrical imperfections of the LAD detector assembly, and the effects of its border pixels with different responses and sizes. We demonstrate the results on the final reconstructed images based on uncorrected and corrected projections, where we achieved a 1 μm voxel size.

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A reference sample for investigating the stability of the imaging system of x-ray computed tomography

Cited by 17 publications

References 7 publications

X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

Evaluation of X-ray computed tomography for surface texture measurements using a prototype additively manufactured reference standard

High resolution X-ray micro-CT imaging of fibrin scaffold using large area single photon counting detector

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