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Title: Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy

Abstract

Purpose: To quantitatively evaluate the long-term image panel positioning stability and gantry angle dependence for gantry-mounted kV imaging systems. Methods: For patient setup digital imaging systems in isocentric rotating proton beam delivery facilities, physical crosshairs are commonly inserted into the snout to define the kV x-ray beam isocenter. Utilizing an automatic detection algorithm, the authors analyzed the crosshair center positions in 2744 patient setup kV images acquired with the four imagers in two treatment rooms from January 2012 to January 2013. The crosshair position was used as a surrogate for imaging panel position, and its long-term stability at the four cardinal angles and the panel flex dependency on gantry angle was investigated. Results: The standard deviation of the panel position distributions was within 0.32 mm (with the range of variation less than ± 1.4 mm) in both the X-Z plane and Y direction. The mean panel inplane rotations were not more than 0.51° for the four panels at the cardinal angles, with standard deviations ≤0.26°. The panel position variations with gantry rotation due to gravity (flex) were within ±4 mm, and were panel-specific. Conclusions: The authors demonstrated that the kV image panel positions in our proton treatment system were highlymore » reproducible at the cardinal angles over 13 months and also that the panel positions can be correlated to gantry angles. This result indicates that the kV image panel positions are stable over time; the amount of panel sag is predictable during gantry rotation and the physical crosshair for kV imaging may eventually be removed, with the imaging beam isocenter position routinely verified by adequate quality assurance procedures and measurements.« less

Authors:
; ; ;  [1]
  1. Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 (United States)
Publication Date:
OSTI Identifier:
22250831
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 41; Journal Issue: 4; Other Information: (c) 2014 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; BEAM POSITION; IMAGES; PATIENTS; PROTON BEAMS; QUALITY ASSURANCE; RADIOTHERAPY; STABILITY; X RADIATION

Citation Formats

Zhu, Mingyao, Botticello, Thomas, Lu, Hsiao-Ming, and Winey, Brian. Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy. United States: N. p., 2014. Web. doi:10.1118/1.4868460.
Zhu, Mingyao, Botticello, Thomas, Lu, Hsiao-Ming, & Winey, Brian. Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy. United States. https://doi.org/10.1118/1.4868460
Zhu, Mingyao, Botticello, Thomas, Lu, Hsiao-Ming, and Winey, Brian. 2014. "Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy". United States. https://doi.org/10.1118/1.4868460.
@article{osti_22250831,
title = {Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy},
author = {Zhu, Mingyao and Botticello, Thomas and Lu, Hsiao-Ming and Winey, Brian},
abstractNote = {Purpose: To quantitatively evaluate the long-term image panel positioning stability and gantry angle dependence for gantry-mounted kV imaging systems. Methods: For patient setup digital imaging systems in isocentric rotating proton beam delivery facilities, physical crosshairs are commonly inserted into the snout to define the kV x-ray beam isocenter. Utilizing an automatic detection algorithm, the authors analyzed the crosshair center positions in 2744 patient setup kV images acquired with the four imagers in two treatment rooms from January 2012 to January 2013. The crosshair position was used as a surrogate for imaging panel position, and its long-term stability at the four cardinal angles and the panel flex dependency on gantry angle was investigated. Results: The standard deviation of the panel position distributions was within 0.32 mm (with the range of variation less than ± 1.4 mm) in both the X-Z plane and Y direction. The mean panel inplane rotations were not more than 0.51° for the four panels at the cardinal angles, with standard deviations ≤0.26°. The panel position variations with gantry rotation due to gravity (flex) were within ±4 mm, and were panel-specific. Conclusions: The authors demonstrated that the kV image panel positions in our proton treatment system were highly reproducible at the cardinal angles over 13 months and also that the panel positions can be correlated to gantry angles. This result indicates that the kV image panel positions are stable over time; the amount of panel sag is predictable during gantry rotation and the physical crosshair for kV imaging may eventually be removed, with the imaging beam isocenter position routinely verified by adequate quality assurance procedures and measurements.},
doi = {10.1118/1.4868460},
url = {https://www.osti.gov/biblio/22250831}, journal = {Medical Physics},
issn = {0094-2405},
number = 4,
volume = 41,
place = {United States},
year = {Tue Apr 15 00:00:00 EDT 2014},
month = {Tue Apr 15 00:00:00 EDT 2014}
}