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Proceedings Paper

Characterization of operating parameters of an in vivo micro CT system
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Paper Abstract

The objective of this study was to characterize the operating parameters of an in-vivo micro CT system. In-plane spatial resolution, noise, geometric accuracy, CT number uniformity and linearity, and phase effects were evaluated using various phantoms. The system employs a flat panel detector with a 127 μm pixel pitch, and a micro focus x-ray tube with a focal spot size ranging from 5-30 μm. The system accommodates three magnification sets of 1.72, 2.54 and 5.10. The in-plane cutoff frequencies (10% MTF) ranged from 2.31 lp/mm (60 mm FOV, M=1.72, 2×2 binning) to 13 lp/mm (10 mm FOV, M=5.10, 1×1 binning). The results were qualitatively validated by a resolution bar pattern phantom and the smallest visible lines were in 30-40 μm range. Noise power spectrum (NPS) curves revealed that the noise peaks exponentially increased as the geometric magnification (M) increased. True in-plane pixel spacing and slice thickness were within 2% of the system’s specifications. The CT numbers in cone beam modality are greatly affected by scattering and thus they do not remain the same in the three magnifications. A high linear relationship (R2 > 0.999) was found between the measured CT numbers and Hydroxyapatite (HA) loadings of the rods of a water filled mouse phantom. Projection images of a laser cut acrylic edge acquired at a small focal spot size of 5 μm with 1.5 fps revealed that noticeable phase effects occur at M=5.10 in the form of overshooting at the boundary of air and acrylic. In order to make the CT numbers consistent across all the scan settings, scatter correction methods may be a valuable improvement for this system.

Paper Details

Date Published: 9 March 2016
PDF: 7 pages
Proc. SPIE 9709, Biophotonics and Immune Responses XI, 97090M (9 March 2016); doi: 10.1117/12.2209626
Show Author Affiliations
Muhammad U. Ghani, Univ. of Oklahoma (United States)
Liqiang Ren, Univ. of Oklahoma (United States)
Kai Yang, Massachusetts General Hospital (United States)
Wei R. Chen, Univ. of Central Oklahoma (United States)
Xizeng Wu, Univ. of Alabama at Birmingham (United States)
Hong Liu, Univ. of Oklahoma (United States)


Published in SPIE Proceedings Vol. 9709:
Biophotonics and Immune Responses XI
Wei R. Chen, Editor(s)

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