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Proceedings Paper

Feasibility of monitoring patient motion with opposed stereo infrared cameras during supine medical imaging
Author(s): Richard D. Beach; Joseph E. McNamara; George Terlecki; Michael A. King
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Paper Abstract

Patient motion during single photon emission computed tomographic (SPECT) acquisition causes inconsistent projection data and reconstruction artifacts which can significantly affect diagnostic accuracy. We have investigated use of the Polaris stereo infrared motion-tracking system to track 6-Degrees-of-Freedom (6-DOF) motion of spherical reflectors (markers) on stretchy bands about the patient's chest and abdomen during cardiac SPECT imaging. The marker position information, obtained by opposed stereo infrared-camera systems, requires processing to correctly record tracked markers, and map Polaris co-ordinate data into the SPECT co-ordinate system. One stereo camera views the markers from the patient's head direction, and the other from the patient's foot direction. The need for opposed cameras is to overcome anatomical and geometrical limitations which sometimes prevent all markers from being seen by a single stereo camera. Both sets of marker data are required to compute rotational and translational 6-DOF motion of the patient which ultimately will be used for SPECT patient-motion corrections. The processing utilizes an algorithm involving least-squares fitting, to each other, of two 3-D point sets using singular value decomposition (SVD) resulting in the rotation matrix and translation of the rigid body centroid. We have previously demonstrated the ability to monitor multiple markers for twelve patients viewing from the foot end, and employed a neural network to separate the periodic respiratory motion component of marker motion from aperiodic body motion. We plan to initiate routine 6-DOF tracking of patient motion during SPECT imaging in the future, and are herein evaluating the feasibility of employing opposed stereo cameras.

Paper Details

Date Published: 23 October 2006
PDF: 11 pages
Proc. SPIE 6380, Smart Medical and Biomedical Sensor Technology IV, 63800T (23 October 2006); doi: 10.1117/12.686369
Show Author Affiliations
Richard D. Beach, Univ. of Massachusetts Medical School (United States)
Joseph E. McNamara, Univ. of Massachusetts Medical School (United States)
George Terlecki, Northern Digital, Inc. (Canada)
Michael A. King, Univ. of Massachusetts Medical School (United States)

Published in SPIE Proceedings Vol. 6380:
Smart Medical and Biomedical Sensor Technology IV
Brian M. Cullum; J. Chance Carter, Editor(s)

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