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Title: Tracking moving objects with megavoltage portal imaging: A feasibility study

Abstract

Four different algorithms were investigated with the aim to determine their suitability to track an object in conventional megavoltage portal images. The algorithms considered were the mean of the sum of squared differences (MSSD), mutual information (MI), the correlation ratio (CR), and the correlation coefficient (CC). Simulation studies were carried out with various image series containing a rigid object of interest that was moved along a predefined trajectory. For each of the series the signal-to-noise ratio (SNR) was varied to compare the performance of the algorithms under noisy conditions. For a poor SNR of -6 dB the mean tracking error was 2.4, 6.5, 39.0, and 17.2 pixels for MSSD, CC, CR and MI, respectively, with a standard deviation of 1.9, 12.9, 19.5, and 7.5 pixels, respectively. The size of a pixel was 0.5 mm. These results improved to 1.1, 1.3, 1.3, and 2.0 pixels, respectively, with a standard deviation of 0.6, 0.8, 0.8, and 2.1 pixels, respectively, when a mean filter was applied to the images prior to tracking. The implementation of MSSD into existing in-house software demonstrated that, depending on the search range, it was possible to process between 2 and 15 images/s, making this approach capable of real-timemore » applications. In conclusion, the best geometric tracking accuracy overall was obtained with MSSD, followed by CC, CR, and MI. The simplest and best algorithm, both in terms of geometric accuracy as well as computational cost, was the MSSD algorithm and was therefore the method of choice.« less

Authors:
; ; ; ; ;  [1]
  1. Department of Radiation Oncology, University of Wuerzburg, Josef-Schneider-Strasse 11, D-97080 Wuerzburg (Germany)
Publication Date:
OSTI Identifier:
20775199
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 33; Journal Issue: 5; Other Information: DOI: 10.1118/1.2191009; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; ALGORITHMS; COMPUTER CODES; FEASIBILITY STUDIES; IMAGES; NEOPLASMS; PARTICLE TRACKS; PERFORMANCE; RADIOTHERAPY; SIGNAL-TO-NOISE RATIO

Citation Formats

Meyer, Juergen, Richter, Anne, Baier, Kurt, Wilbert, Juergen, Guckenberger, Matthias, and Flentje, Michael. Tracking moving objects with megavoltage portal imaging: A feasibility study. United States: N. p., 2006. Web. doi:10.1118/1.2191009.
Meyer, Juergen, Richter, Anne, Baier, Kurt, Wilbert, Juergen, Guckenberger, Matthias, & Flentje, Michael. Tracking moving objects with megavoltage portal imaging: A feasibility study. United States. doi:10.1118/1.2191009.
Meyer, Juergen, Richter, Anne, Baier, Kurt, Wilbert, Juergen, Guckenberger, Matthias, and Flentje, Michael. Mon . "Tracking moving objects with megavoltage portal imaging: A feasibility study". United States. doi:10.1118/1.2191009.
@article{osti_20775199,
title = {Tracking moving objects with megavoltage portal imaging: A feasibility study},
author = {Meyer, Juergen and Richter, Anne and Baier, Kurt and Wilbert, Juergen and Guckenberger, Matthias and Flentje, Michael},
abstractNote = {Four different algorithms were investigated with the aim to determine their suitability to track an object in conventional megavoltage portal images. The algorithms considered were the mean of the sum of squared differences (MSSD), mutual information (MI), the correlation ratio (CR), and the correlation coefficient (CC). Simulation studies were carried out with various image series containing a rigid object of interest that was moved along a predefined trajectory. For each of the series the signal-to-noise ratio (SNR) was varied to compare the performance of the algorithms under noisy conditions. For a poor SNR of -6 dB the mean tracking error was 2.4, 6.5, 39.0, and 17.2 pixels for MSSD, CC, CR and MI, respectively, with a standard deviation of 1.9, 12.9, 19.5, and 7.5 pixels, respectively. The size of a pixel was 0.5 mm. These results improved to 1.1, 1.3, 1.3, and 2.0 pixels, respectively, with a standard deviation of 0.6, 0.8, 0.8, and 2.1 pixels, respectively, when a mean filter was applied to the images prior to tracking. The implementation of MSSD into existing in-house software demonstrated that, depending on the search range, it was possible to process between 2 and 15 images/s, making this approach capable of real-time applications. In conclusion, the best geometric tracking accuracy overall was obtained with MSSD, followed by CC, CR, and MI. The simplest and best algorithm, both in terms of geometric accuracy as well as computational cost, was the MSSD algorithm and was therefore the method of choice.},
doi = {10.1118/1.2191009},
journal = {Medical Physics},
issn = {0094-2405},
number = 5,
volume = 33,
place = {United States},
year = {2006},
month = {5}
}