18 March 2015 Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype
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Abstract
Scanning-beam digital x-ray (SBDX) is an inverse geometry fluoroscopy system for low dose cardiac imaging. The use of a narrow scanned x-ray beam in SBDX reduces detected x-ray scatter and improves dose efficiency, however the tight beam collimation also limits the maximum achievable x-ray fluence. To increase the fluence available for imaging, we have constructed a new SBDX prototype with a wider x-ray beam, larger-area detector, and new real-time image reconstructor. Imaging is performed with a scanning source that generates 40,328 narrow overlapping projections from 71 x 71 focal spot positions for every 1/15 s scan period. A high speed 2-mm thick CdTe photon counting detector was constructed with 320x160 elements and 10.6 cm x 5.3 cm area (full readout every 1.28 s), providing an 86% increase in area over the previous SBDX prototype. A matching multihole collimator was fabricated from layers of tungsten, brass, and lead, and a multi-GPU reconstructor was assembled to reconstruct the stream of captured detector images into full field-of-view images in real time. Thirty-two tomosynthetic planes spaced by 5 mm plus a multiplane composite image are produced for each scan frame. Noise equivalent quanta on the new SBDX prototype measured 63%-71% higher than the previous prototype. X-ray scatter fraction was 3.9-7.8% when imaging 23.3-32.6 cm acrylic phantoms, versus 2.3- 4.2% with the previous prototype. Coronary angiographic imaging at 15 frame/s was successfully performed on the new SBDX prototype, with live display of either a multiplane composite or single plane image.
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Michael A. Speidel, Michael T. Tomkowiak, Amish N. Raval, David A. P. Dunkerley, Jordan M. Slagowski, Paul Kahn, Jamie Ku, Tobias Funk, "Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94121W (18 March 2015); doi: 10.1117/12.2081716; https://doi.org/10.1117/12.2081716
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