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Title: An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation

Abstract

We have developed an independent algorithm for the prediction of electronic portal imaging device (EPID) response. The algorithm uses a set of images [open beam, closed multileaf collimator (MLC), various fence and modified sweeping gap patterns] to separately characterize the primary and head-scatter contributions to EPID response. It also characterizes the relevant dosimetric properties of the MLC: Transmission, dosimetric gap, MLC scatter [P. Zygmansky et al., J. Appl. Clin. Med. Phys. 8(4) (2007)], inter-leaf leakage, and tongue and groove [F. Lorenz et al., Phys. Med. Biol. 52, 5985-5999 (2007)]. The primary radiation is modeled with a single Gaussian distribution defined at the target position, while the head-scatter radiation is modeled with a triple Gaussian distribution defined downstream of the target. The distances between the target and the head-scatter source, jaws, and MLC are model parameters. The scatter associated with the EPID is implicit in the model. Open beam images are predicted to within 1% of the maximum value across the image. Other MLC test patterns and intensity-modulated radiation therapy fluences are predicted to within 1.5% of the maximum value. The presented method was applied to the Varian aS500 EPID but is designed to work with any planar detector with sufficientmore » spatial resolution.« less

Authors:
;  [1]
  1. North Shore Cancer Center, 17 Centennial Drive, Peabody, Massachusetts 01960 (United States)
Publication Date:
OSTI Identifier:
21120740
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 35; Journal Issue: 6; Other Information: DOI: 10.1118/1.2911870; (c) 2008 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; ALGORITHMS; BIOLOGICAL RADIATION EFFECTS; COLLIMATORS; DOSIMETRY; GAUSS FUNCTION; IMAGES; RADIOTHERAPY; SPATIAL RESOLUTION

Citation Formats

Rosca, Florin, Zygmanski, Piotr, and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation. United States: N. p., 2008. Web. doi:10.1118/1.2911870.
Rosca, Florin, Zygmanski, Piotr, & Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation. United States. https://doi.org/10.1118/1.2911870
Rosca, Florin, Zygmanski, Piotr, and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. 2008. "An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation". United States. https://doi.org/10.1118/1.2911870.
@article{osti_21120740,
title = {An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation},
author = {Rosca, Florin and Zygmanski, Piotr and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115},
abstractNote = {We have developed an independent algorithm for the prediction of electronic portal imaging device (EPID) response. The algorithm uses a set of images [open beam, closed multileaf collimator (MLC), various fence and modified sweeping gap patterns] to separately characterize the primary and head-scatter contributions to EPID response. It also characterizes the relevant dosimetric properties of the MLC: Transmission, dosimetric gap, MLC scatter [P. Zygmansky et al., J. Appl. Clin. Med. Phys. 8(4) (2007)], inter-leaf leakage, and tongue and groove [F. Lorenz et al., Phys. Med. Biol. 52, 5985-5999 (2007)]. The primary radiation is modeled with a single Gaussian distribution defined at the target position, while the head-scatter radiation is modeled with a triple Gaussian distribution defined downstream of the target. The distances between the target and the head-scatter source, jaws, and MLC are model parameters. The scatter associated with the EPID is implicit in the model. Open beam images are predicted to within 1% of the maximum value across the image. Other MLC test patterns and intensity-modulated radiation therapy fluences are predicted to within 1.5% of the maximum value. The presented method was applied to the Varian aS500 EPID but is designed to work with any planar detector with sufficient spatial resolution.},
doi = {10.1118/1.2911870},
url = {https://www.osti.gov/biblio/21120740}, journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 35,
place = {United States},
year = {Sun Jun 15 00:00:00 EDT 2008},
month = {Sun Jun 15 00:00:00 EDT 2008}
}