18 March 2015 Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype
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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 A. Speidel, Michael T. Tomkowiak, Michael T. Tomkowiak, Amish N. Raval, Amish N. Raval, David A. P. Dunkerley, David A. P. Dunkerley, Jordan M. Slagowski, Jordan M. Slagowski, Paul Kahn, Paul Kahn, Jamie Ku, Jamie Ku, Tobias Funk, 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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