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Title: SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols

Abstract

Purpose: To quantify differences between the TG51 and TG51 addendum calibration protocols. Methods: Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose-to-water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm{sup 2} radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume-averaging correction was applied based on crossline and inline dose profiles. For the TG51 procedure, the collimating jaws were set to 10×10cm{sup 2} according to the digital readout, and a lead foil was used for kQ measurements of energies greater than 10MV. Results: For beam energies with a flattening filter, absorbed dose-to-water determined by the two protocols differed by 0.1%–0.3%. For FFF beam energies, differences between the protocols were up to 0.2% and 0.8% for the scanning and Farmer ionization chambers, respectively. Differences between the protocols were due to kQ determination, volume-averaging correction, and measurement of raw ionization. Differences in kQ values between the two protocols were up to 0.4% and 0.2% for the scanning and Farmer ionization chambers, respectively. Volume-averagingmore » corrections were less than 0.1% for the scanning ionization chamber, and up to 0.4% and 0.6% for the Farmer ionization chamber in beams with a flattening filter and FFF beams, respectively. Raw ionization measurements differed up to 0.3%±0.07% due to differences in jaw settings. Conclusion: The TG51 and TG51 addendum calibration protocols differed less than 0.3% for the scanning ionization chamber. For the Farmer chamber in FFF energies, volume-averaging corrections of up to 0.6% contributed to calibration differences of up to 0.8%. Failure to verify the radiation field size can produce calibration differences of up to 0.3%.« less

Authors:
; ; ;  [1]
  1. University of Pittsburgh Cancer Institute, Pittsburgh, PA (United States)
Publication Date:
OSTI Identifier:
22649075
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CALIBRATION; CORRECTIONS; ION BEAMS; IONIZATION CHAMBERS; READOUT SYSTEMS

Citation Formats

McCaw, T, Hwang, M, Jang, S, and Huq, M. SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols. United States: N. p., 2016. Web. doi:10.1118/1.4956673.
McCaw, T, Hwang, M, Jang, S, & Huq, M. SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols. United States. doi:10.1118/1.4956673.
McCaw, T, Hwang, M, Jang, S, and Huq, M. Wed . "SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols". United States. doi:10.1118/1.4956673.
@article{osti_22649075,
title = {SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols},
author = {McCaw, T and Hwang, M and Jang, S and Huq, M},
abstractNote = {Purpose: To quantify differences between the TG51 and TG51 addendum calibration protocols. Methods: Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose-to-water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm{sup 2} radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume-averaging correction was applied based on crossline and inline dose profiles. For the TG51 procedure, the collimating jaws were set to 10×10cm{sup 2} according to the digital readout, and a lead foil was used for kQ measurements of energies greater than 10MV. Results: For beam energies with a flattening filter, absorbed dose-to-water determined by the two protocols differed by 0.1%–0.3%. For FFF beam energies, differences between the protocols were up to 0.2% and 0.8% for the scanning and Farmer ionization chambers, respectively. Differences between the protocols were due to kQ determination, volume-averaging correction, and measurement of raw ionization. Differences in kQ values between the two protocols were up to 0.4% and 0.2% for the scanning and Farmer ionization chambers, respectively. Volume-averaging corrections were less than 0.1% for the scanning ionization chamber, and up to 0.4% and 0.6% for the Farmer ionization chamber in beams with a flattening filter and FFF beams, respectively. Raw ionization measurements differed up to 0.3%±0.07% due to differences in jaw settings. Conclusion: The TG51 and TG51 addendum calibration protocols differed less than 0.3% for the scanning ionization chamber. For the Farmer chamber in FFF energies, volume-averaging corrections of up to 0.6% contributed to calibration differences of up to 0.8%. Failure to verify the radiation field size can produce calibration differences of up to 0.3%.},
doi = {10.1118/1.4956673},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}