title: Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype.
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 × 71 focal spot positions for every 1/15 s scan period. A high speed 2-mm thick CdTe photon counting detector was constructed with 320×160 elements and 10.6 cm × 5.3 cm area (full readout every 1.28 μs), 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.
authors.affiliation: Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA ; Dept. of Medicine, University of Wisconsin, Madison, WI, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Speidel
authors.affiliation: Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Tomkowiak
authors.affiliation: Dept. of Medicine, University of Wisconsin, Madison, WI, USA.
authors.forename: Amish N
authors.initials: AN
authors.lastname: Raval
authors.affiliation: Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA.
authors.forename: David A P
authors.initials: DA
authors.lastname: Dunkerley
authors.affiliation: Dept. of Medical Physics, University of Wisconsin, Madison, WI, USA.
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Slagowski
authors.affiliation: Triple Ring Technologies, Inc, Newark, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Kahn
authors.affiliation: Triple Ring Technologies, Inc, Newark, CA, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: Ku
authors.affiliation: Triple Ring Technologies, Inc, Newark, CA, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Funk
keywords: photon-counting detector; real-time tomosynthesis; scanning-beam digital x-ray; x-ray fluoroscopy