scholarly journals OBSERVATIONS ON THE PERFORMANCE OF X-RAY COMPUTED TOMOGRAPHY FOR DIMENSIONAL METROLOGY

2016 ◽  
Vol XLI-B5 ◽  
pp. 25-31
Author(s):  
H. C. Corcoran ◽  
S. B. Brown ◽  
S. Robson ◽  
R. D. Speller ◽  
M. B. McCarthy
Keyword(s):  
Computed Tomography ◽  
Reverse Engineering ◽  
X Rays ◽  
Dimensional Metrology ◽  
Beam Hardening ◽  
X Ray ◽  
Accuracy And Precision ◽  
Dimensional Measurements ◽  
X Ray Computed

X-ray computed tomography (XCT) is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

scholarly journals OBSERVATIONS ON THE PERFORMANCE OF X-RAY COMPUTED TOMOGRAPHY FOR DIMENSIONAL METROLOGY

2016 ◽  
Vol XLI-B5 ◽  
pp. 25-31
Author(s):  
H. C. Corcoran ◽  
S. B. Brown ◽  
S. Robson ◽  
R. D. Speller ◽  
M. B. McCarthy
Keyword(s):  
Computed Tomography ◽  
Reverse Engineering ◽  
X Rays ◽  
Dimensional Metrology ◽  
Beam Hardening ◽  
X Ray ◽  
Accuracy And Precision ◽  
Dimensional Measurements ◽  
X Ray Computed

X-ray computed tomography (XCT) is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

Development of Dimensional X-Ray Computed Tomography

2015 ◽  
Vol 9 (5) ◽  
pp. 567-571 ◽  
Author(s):  
Hiroyuki Fujimoto ◽  
◽  
Makoto Abe ◽  
Sonko Osawa ◽  
Osamu Sato ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Coordinate Measuring Machine ◽  
National Metrology Institute ◽  
Maximum Deviation ◽  
Dimensional Metrology ◽  
X Ray ◽  
Tomography System ◽  
Dimensional Measurements ◽  
X Ray Computed ◽  
Measuring Machine

Recently, a strong need has arisen for a dimensional X-ray computed tomography system that is capable of dimensional measurements. This is because the speedy realization of dimensional measurements for outward forms and inward forms on dense spatial points remarkably simplifies and accelerates production loop. However, although the image obtained via XCT describes the structure clearly and in great detail, dimensional metrology by means of XCT is not simple. The National Metrology Institute of Japan has been carrying out performance tests using gauges that include the gauges proposed in ISO10360. In this work, the magnification variation correction is carefully presented, and a maximum deviation of less than 5 μm is shown to be possible by means of the measurement of the forest phantom of 27 ruby spheres, the locations of which are calibrated by the coordinate measuring machine.

Visualizing Fluid Flows With X-Rays

2007 ◽  
Author(s):  
Theodore J. Heindel ◽  
Terrence C. Jensen ◽  
Joseph N. Gray
Keyword(s):  
Computed Tomography ◽  
Flow Visualization ◽  
Three Dimensional ◽  
Fluid Flows ◽  
X Rays ◽  
Radiographic Images ◽  
Optical Access ◽  
X Ray ◽  
X Ray Computed ◽  
Density Map

There are several methods available to visualize fluid flows when one has optical access. However, when optical access is limited to near the boundaries or not available at all, alternative visualization methods are required. This paper will describe flow visualization using an X-ray system that is capable of digital X-ray radiography, digital X-ray stereography, and digital X-ray computed tomography (CT). The unique X-ray flow visualization facility will be briefly described, and then flow visualization of various systems will be shown. Radiographs provide a two-dimensional density map of a three dimensional process or object. Radiographic images of various multiphase flows will be presented. When two X-ray sources and detectors simultaneously acquire images of the same process or object from different orientations, stereographic imaging can be completed; this type of imaging will be demonstrated by trickling water through packed columns and by absorbing water in a porous medium. Finally, local time-averaged phase distributions can be determined from X-ray computed tomography (CT) imaging, and this will be shown by comparing CT images from two different gas-liquid sparged columns.

scholarly journals Automated evaluation of the surface point quality in dimensional X-ray computed tomography

2020 ◽  
Vol 87 (2) ◽  
pp. 111-121 ◽  
Author(s):  
Andreas Michael Müller ◽  
Lorenz Butzhammer ◽  
Florian Wohlgemuth ◽  
Tino Hausotte
Keyword(s):  
Computed Tomography ◽  
Surface Point ◽  
Random Measurement Error ◽  
X Ray ◽  
Random Measurement ◽  
Automated Evaluation ◽  
Dimensional Measurements ◽  
X Ray Computed ◽  
Model Measurement

AbstractX-ray computed tomography (CT) enables dimensional measurements of numerous measurands with a single scan, including the measurement of inner structures. However, measurement artefacts complicate the applicability of the technology in some cases. This paper presents a methodology to assess the surface point quality of computed tomography measurements without the requirement of a CAD model. Measurement artefacts lowering the surface point quality can therefore automatically be detected. The correlation of quality values with the random measurement error is demonstrated. The presented method can in principle be used to weight single fit points to reduce the measurement uncertainty of CT measurements.

scholarly journals Optimization of the energy for Breast monochromatic absorption X-ray Computed Tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pasquale Delogu ◽  
Vittorio Di Trapani ◽  
Luca Brombal ◽  
Giovanni Mettivier ◽  
Angelo Taibi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Imaging Techniques ◽  
Fixed Dose ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
Contrast Resolution ◽  
X Ray ◽  
X Ray Imaging ◽  
X Ray Computed ◽  
Dose Levels

Abstract The limits of mammography have led to an increasing interest on possible alternatives such as the breast Computed Tomography (bCT). The common goal of all X-ray imaging techniques is to achieve the optimal contrast resolution, measured through the Contrast to Noise Ratio (CNR), while minimizing the radiological risks, quantified by the dose. Both dose and CNR depend on the energy and the intensity of the X-rays employed for the specific imaging technique. Some attempts to determine an optimal energy for bCT have suggested the range 22 keV–34 keV, some others instead suggested the range 50 keV–60 keV depending on the parameters considered in the study. Recent experimental works, based on the use of monochromatic radiation and breast specimens, show that energies around 32 keV give better image quality respect to setups based on higher energies. In this paper we report a systematic study aiming at defining the range of energies that maximizes the CNR at fixed dose in bCT. The study evaluates several compositions and diameters of the breast and includes various reconstruction algorithms as well as different dose levels. The results show that a good compromise between CNR and dose is obtained using energies around 28 keV.

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