Performance analysis of a CsI-based flat panel detector in a cone beam variable resolution x-ray system

Bahram Dahi; Gary S. Keyes; David A. Rendon; Frank A. DiBianca

doi:10.1117/12.710180

15 March 2007 Performance analysis of a CsI-based flat panel detector in a cone beam variable resolution x-ray system

Bahram Dahi, Gary S. Keyes, David A. Rendon, Frank A. DiBianca

Author Affiliations +

Proceedings Volume 6510, Medical Imaging 2007: Physics of Medical Imaging; 65104B (2007) https://doi.org/10.1117/12.710180
Event: Medical Imaging, 2007, San Diego, CA, United States

Abstract

A new Cone-Beam CT (CBCT) system is introduced that uses the concept of Variable Resolution X-ray (VRX) detection, which has previously been demonstrated to significantly increase spatial resolution for small objects. An amorphous silicon Flat Panel Detector (FPD) with a CsI scintillator (PaxScan 2020, Varian, Salt Lake City, UT) is coupled with a micro-focus x-ray tube (35 - 80 kVp, 10 - 250 μA) to form a CBCT. The FPD is installed on a rotating arm that can be adjusted to any angle θ, called the VRX angle, between 90° and 0° with respect to the x-ray direction. A VRX angle of 90° for the detector corresponds to a conventional CBCT whereas a VRX angle of 30° means that the detector is tilted 90° - 30° = 60° from its perpendicular position. Tilting the FPD in this manner reduces both the line-spread function width and the sampling distance by a factor of sin(&thgr;), thereby increasing detector spatial resolution proportionately. An in-house phantom is used to measure the MTF of the reconstructed CT images using different VRX angles. An increase by a factor of 1.67 ± 0.007 is observed in the MTF cutoff frequency at 30° compared to 90° in images acquired at 75 kVp. Expected theoretical value for this case is 2.0. The new Cone-Beam Variable Resolution X-ray (CB-VRX) CT system is expected to significantly improve the images acquired from small objects - such as small animals - while exploiting the opportunities offered by a conventional CBCT.

Citation Download Citation

Bahram Dahi, Gary S. Keyes, David A. Rendon, and Frank A. DiBianca "Performance analysis of a CsI-based flat panel detector in a cone beam variable resolution x-ray system", Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 65104B (15 March 2007); https://doi.org/10.1117/12.710180

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