Journal of X-Ray Science and Technology - Volume 9, issue 2

Authors: Ning, Ruola | Wang, Xiaohui | Conover, David | Zhang, Ying

Article Type: Research Article

Abstract: {\it Rational and objectives.} The recent development of image intensifier-based volume tomographic digital angiography has attracted interest in the development of an effective correction protocol for image distortion introduced by an image intensifier (II)-based image chain. This paper presents an effective II distortion-correction method for II-based volume tomographic digital angiography (VTDA). {\it Methods.} In this calibration protocol, two types of predominant distortion: Global variable magnetic field (GVMF) distortion and pincushion distortion …were corrected separately using global mapping functions. GVMF distortion-correction parameters were determined by measuring the translational and rotational parameters from the projection images of a specially designed phantom acquired at different gantry angular positions. A new pincushion distortion-correction algorithm was then developed which remapps projection data acquired with the curved detector onto an imaginary flat detector. The corrected projection data were used for direct 3D reconstruction with a cone-beam reconstruction algorithm for a flat detector. The method was validated through 3D reconstructions of a vascular phantom, a specially designed resolution phantom and animal studies using the newly built II-based volume tomographic digital angiography imaging system. {\it Results.} Artifacts caused by II distortion in reconstructed images can be completely removed using the II distortion-correction technique. With the distortion-correction, the geometric reconstruction accuracy is significantly improved and the maximum error in vessel diameter is reduced from 2.0 mm without distortion-correction, to 0.3 mm. Moreover, after the distortion-correction, the spatial resolution of the system becomes uniform. The results of 3D reconstruction from phantom and animal studies indicate that the accuracy of the distortion-correction technique is acceptable for volume tomographic digital angiography reconstruction. {\it Conclusion.} The distortion-correction technique is efficient and provides acceptable accuracy for volume tomographic digital angiography imaging. Show more

Keywords: Volume CT, angiography, distortion-correction, image intensifier, cone beam reconstruction

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 2, pp. 55-75, 2001

Authors: Kitching, K.J. | Wilson, D.J. | Doherty, P.J. | Williams, R.L.

Article Type: Research Article

Abstract: X-Ray Photoelectron Spectroscopy (XPS) has been employed to determine the effect on a biomedical polyurethane, following plasma treatment._2 and Ar irradiation show addition of oxygen containing species, whilst N_2 suggests an etching mechanism. Storage in air results in loss of some introduced groups but not total regeneration of material properties.

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 2, pp. 77-83, 2001

Authors: Cornaby, S. | Reyes-Mena, A. | Pew, H.K. | Moody, P.W. | Hughes, T. | Stradling, A. | Knight, L.V.

Article Type: Research Article

Abstract: A breadboard setup constructed at MOXTEK, Inc. is capable of capturing both x-ray fluorescence (XRF) and x-ray diffraction (XRD) information simultaneously using a charge-coupled device (CCD) as the x-ray detector. Each pixel on the CCD is used as a single event energy-dispersive detector. NASA is funding the instrument's construction because of its capabilities and small size. The CCD captures both the energy and the position of an x-ray photon. With the energy and spatial information we …are able to construct fluorescence spectra as well as diffraction patterns. X-ray events that deposit their energy in one pixel (single events) are kept, and x-ray events that split into two or more pixels (split events) are discarded from the data set. This paper focuses on how the CCD captures x-ray information and how the information is sorted by means of algorithms to provide both XRF and XRD information. Show more

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 2, pp. 85-97, 2001

Article Type: Other

Citation: Journal of X-Ray Science and Technology, vol. 9, no. 2, pp. 99-100, 2001