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Patient specific quality assurance: Transition from IMRT to IMAT

Publication ,  Journal Article
O'Daniel, J; Das, S; Wu, J; Yin, FF
Published in: Journal of Physics: Conference Series
January 1, 2010

The purpose of this study was to test a patient-specific quality assurance (QA) protocol for intensity-modulated arc radiotherapy (IMAT), and to evaluate the use of an intensity-modulated stationary radiotherapy QA device (2D ion chamber array). Thirty-nine IMAT treatment plans for brain, spine, and prostate were analyzed using 3 methods: ion chamber (1D absolute, n=39), film (2D relative, coronal/sagittal, n=8), and 2D ion chamber array ("ICA," 2D absolute, coronal/sagittal, n=39) measurements. All measurements were compared to the treatment planning system (TPS) dose calculation with gamma analysis (3%, 3mm distance-to-agreement criteria) or absolute point dose comparison. The ICA measurements were also directly compared to film and ion chamber for validation. Absolute 1D measurements agreed well calculation (ion chamber: average deviation 1.4%, range -0.9% to 2.8%; ICA: average deviation 0.7%, range -1.8% to 2.9%). Relative 2D measurements also showed good agreement with calculation (>93% of pixels in all films passing gamma, >90% of pixels in all ICA measurements passing gamma). ICA and film relative dose results were highly similar (> 90% of pixels passing gamma in 94% of QAs). Coronal and sagittal ICA measurements were statistically indistinguishable by the paired t-test with a hypothesized mean difference of 0.2%. Ion chamber and ICA absolute dose measurements usually agreed well, but had disparities of 2-3% in 18% of plans. After validating the new IMAT implementation with ion chamber, film, and ICA, we reduced our QA from 5 (ion chamber, film, and ICA) to 2 measurements (ion chamber and single ICA) per plan. The ICA (Matrixx®, IBA Dosimetry) was validated in relative analysis mode, but ion chamber measurements are recommended for absolute dose comparison. © 2010 IOP Publishing Ltd.

Duke Scholars

Published In

Journal of Physics: Conference Series

DOI

EISSN

1742-6596

ISSN

1742-6588

Publication Date

January 1, 2010

Volume

250

Start / End Page

231 / 234

Related Subject Headings

  • 51 Physical sciences
  • 0299 Other Physical Sciences
  • 0204 Condensed Matter Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
 

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O’Daniel, J., Das, S., Wu, J., & Yin, F. F. (2010). Patient specific quality assurance: Transition from IMRT to IMAT. Journal of Physics: Conference Series, 250, 231–234. https://doi.org/10.1088/1742-6596/250/1/012050
O’Daniel, J., S. Das, J. Wu, and F. F. Yin. “Patient specific quality assurance: Transition from IMRT to IMAT.” Journal of Physics: Conference Series 250 (January 1, 2010): 231–34. https://doi.org/10.1088/1742-6596/250/1/012050.
O’Daniel J, Das S, Wu J, Yin FF. Patient specific quality assurance: Transition from IMRT to IMAT. Journal of Physics: Conference Series. 2010 Jan 1;250:231–4.
O’Daniel, J., et al. “Patient specific quality assurance: Transition from IMRT to IMAT.” Journal of Physics: Conference Series, vol. 250, Jan. 2010, pp. 231–34. Scopus, doi:10.1088/1742-6596/250/1/012050.
O’Daniel J, Das S, Wu J, Yin FF. Patient specific quality assurance: Transition from IMRT to IMAT. Journal of Physics: Conference Series. 2010 Jan 1;250:231–234.
Journal cover image

Published In

Journal of Physics: Conference Series

DOI

EISSN

1742-6596

ISSN

1742-6588

Publication Date

January 1, 2010

Volume

250

Start / End Page

231 / 234

Related Subject Headings

  • 51 Physical sciences
  • 0299 Other Physical Sciences
  • 0204 Condensed Matter Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics