&lt;title&gt;X-ray cone beam CT system calibration&lt;/title&gt;

Sire, Pascal; Rizo, P.; Martin, Megan M.

doi:10.1117/12.164741

Cited by 9 publications

(11 citation statements)

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“…stage. One of the earlier studies [65] proposes a set of procedures to analytically determine misalignments and offsets in cone-beam systems using a grid-plate with regularly distributed holes. Each hole is identified sequentially by a number = i 1 to N (figure 18(a)).…”

Section: Methods Based On Fixed or Limited Positions Of The Rotationmentioning

confidence: 99%

Towards geometrical calibration of x-ray computed tomography systems—a review

Ferrucci

Leach

Giusca

et al. 2015

Meas. Sci. Technol.

131

100

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Industrial X-ray computed tomography (XCT) is seen as a potentially effective tool for industrial inspection of complex parts. In particular, XCT is an attractive solution for the measurement of internal geometries, which are inaccessible by conventional coordinate measuring systems (CMSs). While the technology is available and the benefits are recognized, methods to establish measurement assurance of XCT systems are lacking. More specifically, assessment of measurement uncertainty and the subsequent establishment of measurement traceability is a largely unknown process. This paper is a review of research that contributes to the development of a geometrical calibration procedure for XCT systems. A brief introduction to the geometry of cone-beam tomography systems is given, after which the geometrical influence factors are outlined. Mathematical measurement models play a significant role in understanding how geometrical offsets and misalignments contribute to error in measurements; therefore, the application of mathematical models in simulating geometrical errors is discussed and the corresponding literature is presented. Then, the various methods that have been developed to measure certain geometrical errors are reviewed. The findings from this review are discussed and suggestions are provided for future work towards the development of a comprehensive and practical geometrical calibration procedure.

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Section: Methods Based On Fixed or Limited Positions Of The Rotationmentioning

confidence: 99%

Towards geometrical calibration of x-ray computed tomography systems—a review

Ferrucci

Leach

Giusca

et al. 2015

Meas. Sci. Technol.

131

100

View full text Add to dashboard Cite

show abstract

“…For the assessment of geometric errors, manufacturers prescribe proprietary procedures that use, e.g. : (a) a bar with two steel spheres of different sizes encapsulated in it for calibrating preset magnification positions [2]; (b) a two-layer grid plate with uniformly spaced holes for checking and numerically correcting the tilt of the rotation axis about the normal to the detector and the offset of the rotation axis from the magnification axis [3]; or (c) a phantom for checking the horizontal position of the rotation axis and numerically correcting it over the entire magnification axis [4]. Being those proprietary procedures either part of the protocol performed by the manufacturer during regular service interventions or black-box procedures that must be followed by the user periodically to keep the errors within reasonable limits, they do not allow the user to assess their effect on the measurement uncertainty.…”

Section: Introductionmentioning

confidence: 99%

Geometric errors of CT scanners and their estimation by imaging a reference object

Baldo¹,

Probst²,

Dewulf³

2022

eJNDT

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Computed Tomography (CT) has been included in the routine of the dimensional quality loop of manufactured products over the past two decades. Characterized by a complex measurement chain, many influence factors may affect the accuracy of CT measurements. Misalignments stemming from imperfections of the components of the CT metrology instrument exemplify an influence factor over which the user may have no control. In this regard, this paper describes the experimental study of the geometric errors of a CT instrument using an image-based method to map them. The experiments were designed with the purposes of understanding the time-related variation pattern of the geometric errors and assessing the actual measurement capability of the image-based method itself to discriminate the geometric errors. The experimental findings can contribute to an optimized use of the CT technology for dimensional measurements, for example, by assisting the proper actions to be taken by the user for error correction.

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“…In contrast to image intensifiers, which have pincushion distortion of up to several millimetres [11][12][13], the geometry distortions of the scintillator-based flat-panel detectors used in radiographic imaging systems were usually considered negligible [6]. The only study known to us that corrects geometric detector distortions for dimensional CT was performed by Weiss et al [14], who measured flat-panel detector distortions of up to ±0.15 pixel (0.05 pixel on average) per coordinate using a calibrated ball plate.…”

Section: Introductionmentioning

confidence: 99%

X-ray flat-panel detector geometry correction to improve dimensional computed tomography measurements

Luethi

Bircher

Meli

et al. 2019

Meas. Sci. Technol.

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To improve the accuracy of dimensional x-ray computed tomography (CT), error sources have to be characterised and accounted for. A variety of error sources have been comprehensively described in the literature. However, the influence of geometrical distortion of the flat-panel detector has rarely been considered. In this paper, the deviation from nominal geometry of a flat-panel x-ray detector was characterised using a calibrated ball plate. In-plane deviations were separated from the detector topography by varying the source–detector distance, resulting in a 3D detector geometry. A correction model for arbitrary source–detector distances was developed, which reduced the maximum errors of sphere centre-to-centre distances in scale-corrected CT measurements from ±3.9 µm to below ±0.8 µm. This fivefold improvement emphasises the importance of such correction for dimensional CT.

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<title>X-ray cone beam CT system calibration</title>

Cited by 9 publications

References 0 publications

Towards geometrical calibration of x-ray computed tomography systems—a review

Towards geometrical calibration of x-ray computed tomography systems—a review

Geometric errors of CT scanners and their estimation by imaging a reference object

X-ray flat-panel detector geometry correction to improve dimensional computed tomography measurements

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