X-ray Computed Tomography Case Study: Triangle and Pentagon Datasets with Various Sizes, Scales, and Noise Levels

Description

Sample information:

The dataset consists of two laser-cut objects made from a 6-mm-thick transparent plastic material called acrylate. The objects have triangular and pentagonal shapes, each containing 12 samples with varying sizes. The right-angle edges of the triangular samples range from 2.8 cm to 4.0 cm, while the edges of the pentagonal samples range from 2.5 cm to 3.0 cm. Each scanning session involved different placements of the objects, resulting in variations in rotation and translation.

Scanner information

The dataset is acquired in the FleX-ray Laboratory, developed by TESCAN-XRE, located at CWI in Amsterdam. The CT scanner consists of a cone-beam microfocus polychromatic X-ray point source, and a 1944x1536 pixel, 14-bit, flat detector panel (Dexela1512NDT). Full details can be found in [Coban 2020].

Scanning geometry

A Region-of-Interest (ROI) scanning approach was used to acquire projections with dimensions of 956 X 10 pixels. The source-to-object and detector-to-object distances were both set to 225 mm. 

Scanning settings

A peak voltage of 90 kV was used. An exposure time of 80 ms per projection was applied, and the source spectrum was shaped using filters consisting of 0.1 mm zinc, 0.2 mm copper, and 0.5 mm aluminum. A total of 3601 projections were acquired. To create a dataset with three noise levels, three emission currents were used: 600 μA, 300 μA, and 100 μA. The lower emission current (100 μA) produced data with higher noise levels. Finally, 12 groups of projections were acquired for each shape and each noise level, resulting in a total of 48 groups of projections. 

Reconstruction

The script fan_beam_reconstruction.py uses the ASTRA toolbox [Aarle 2015, Aarle 2016] to reconstruct the dataset. It focuses on the middle row of the detector to approximate fan-beam geometry.

File name description

For example, Triangle_600 represents triangular samples scanned at an emission current of 600 μA. Files within that folder—like Triangle_600_1—denote individual samples (in this case, the first sample).

Research group
These datasets are produced by the Computational Imaging group at Centrum Wiskunde & Informatica (CI-CWI) in Amsterdam, The Netherlands: https://www.cwi.nl/research/groups/computational-imaging

Contact details

tianyuan.wang@cwi.nl

Acknowledgments

This work was supported by the European Union H2020-MSCA-ITN-2020 under Grant Agreement Nember 956172 (xCTing). 

References

[Coban 2020] S. B. Coban, F. Lucka, W. J. Palenstijn, D. Van Loo, and K. J. Batenburg, "Explorative imaging and its implementation at the FleX-ray Laboratory," J. Imaging, vol. 6, no. 18, 2020, doi: 10.3390/jimaging6040018.

[Aarle 2015] W. V. Aarle et al., "The ASTRA toolbox: A platform for advanced algo- rithm development in electron tomography," Ultramicroscopy, vol. 157, pp. 35–47, 2015.

[Aarle 2016] W. V. Aarle et al., "Fast and flexible X-ray tomography using the ASTRA toolbox," Opt. Exp., vol. 24, no. 22, pp. 25129–25147, 2016.