Program Information
Geometry Repeatability for Diagnostic Cone-Beam Imaging in the Emergency Department Using a Twin Robotic X-Ray System
M Herbst1 , F Noo2*, A Fieselmann1 , S Vogt3 , L Ritschl1 , T Mertelmeier1 , (1) Siemens Healthcare, GmbH, Forchheim, Germany, (2) University of Utah, Salt Lake City, UT, (3) Siemens Medical Solutions USA, Malvern, PA
Presentations
SU-E-201-1 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 201
Purpose: Diagnostic cone-beam imaging in the emergency department (ED) has become possible with a highly-versatile twin-robotic x-ray system (Multitom Rax, Siemens Healthcare, GmbH) that can perform conventional X-ray imaging and fluoroscopy as well as 3D tomography. We wish to assess repeatability of cone-beam imaging trajectories on this system. To accommodate ED patient throughput, high repeatability is desired, so that down times for geometry calibration can be limited to periods of low activity.
Methods: Repeated scans of a high-precision calibration phantom were performed for 5 trajectories, with a system in clinical ED use. The repeated scans included a sequence of 5 or 6 successive scans on a given day, followed by 2 successive scans three weeks later. Successive scans were separated by a few minutes during which the source and detector were individually displaced to account for possible system utilization for another clinical task. The system was in full clinical use during the three weeks separating the two sets of successive scans. The 5 trajectories enable left-arm, right-arm, resting-neck, and weight-bearing neck or knee imaging. A metric that evaluates back-projection accuracy over the field-of-view was used to assess repeatability.
Results: Repeatability was higher across successive scans performed on a given day than with a 3-week delay; and repeatability for weight-bearing knee imaging was lowest, presumably because it involves the longest extension of telescopic source/detector arms. However, strong repeatability was observed on a frame-by-frame basis as well as over the whole scan, with a mean back-projection error systematically below 0.16 mm.
Conclusion: Repeatability appears sufficient for ED needs. Geometric stability is at least guaranteed over 3 weeks (the interval investigated in this study) and is in average similar to that observed with fixed C-arm systems. Further study will confirm geometry accuracy with repeated scans of the ACR CT accreditation phantom.
Funding Support, Disclosures, and Conflict of Interest: This work is supported by a research contract between The University of Utah and Siemens Medical Solutions, USA.
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