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A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac.

Publication ,  Journal Article
Liu, B; Adamson, J; Rodrigues, A; Zhou, F; Yin, F-F; Wu, Q
Published in: Phys Med Biol
October 7, 2013

Volumetric modulated arc therapy (VMAT) is a relatively new treatment modality for dynamic photon radiation therapy. Pre-treatment quality assurance (QA) is necessary and many efforts have been made to apply electronic portal imaging device (EPID)-based IMRT QA methods to VMAT. It is important to verify the gantry rotation speed during delivery as this is a new variable that is also modulated in VMAT. In this paper, we present a new technique to perform VMAT QA using an EPID. The method utilizes EPID cine mode and was tested on Varian TrueBeam in research mode. The cine images were acquired during delivery and converted to dose matrices after profile correction and dose calibration. A sub-arc corresponding to each cine image was extracted from the original plan and its portal image prediction was calculated. Several analyses were performed including 3D γ analysis (2D images + gantry angle axis), 2D γ analysis, and other statistical analyses. The method was applied to 21 VMAT photon plans of 3 photon energies. The accuracy of the cine image information was investigated. Furthermore, this method's sensitivity to machine delivery errors was studied. The pass rate (92.8 ± 1.4%) for 3D γ analysis was comparable to those from Delta(4) system (99.9 ± 0.1%) under similar criteria (3%, 3 mm, 5% threshold and 2° angle to agreement) at 6 MV. The recorded gantry angle and start/stop MUs were found to have sufficient accuracy for clinical QA. Machine delivery errors can be detected through combined analyses of 3D γ, gantry angle, and percentage dose difference. In summary, we have developed and validated a QA technique that can simultaneously verify the gantry angle and delivered MLC fluence for VMAT treatment.This technique is efficient and its accuracy is comparable to other QA methods.

Duke Scholars

Published In

Phys Med Biol

DOI

EISSN

1361-6560

Publication Date

October 7, 2013

Volume

58

Issue

19

Start / End Page

6683 / 6700

Location

England

Related Subject Headings

  • Radiotherapy, Intensity-Modulated
  • Quality Control
  • Nuclear Medicine & Medical Imaging
  • Medical Errors
  • Electrical Equipment and Supplies
  • 5105 Medical and biological physics
  • 1103 Clinical Sciences
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences
 

Citation

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Liu, B., Adamson, J., Rodrigues, A., Zhou, F., Yin, F.-F., & Wu, Q. (2013). A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac. Phys Med Biol, 58(19), 6683–6700. https://doi.org/10.1088/0031-9155/58/19/6683
Liu, Bo, Justus Adamson, Anna Rodrigues, Fugen Zhou, Fang-fang Yin, and Qiuwen Wu. “A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac.Phys Med Biol 58, no. 19 (October 7, 2013): 6683–6700. https://doi.org/10.1088/0031-9155/58/19/6683.
Liu B, Adamson J, Rodrigues A, Zhou F, Yin F-F, Wu Q. A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac. Phys Med Biol. 2013 Oct 7;58(19):6683–700.
Liu, Bo, et al. “A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac.Phys Med Biol, vol. 58, no. 19, Oct. 2013, pp. 6683–700. Pubmed, doi:10.1088/0031-9155/58/19/6683.
Liu B, Adamson J, Rodrigues A, Zhou F, Yin F-F, Wu Q. A novel technique for VMAT QA with EPID in cine mode on a Varian TrueBeam linac. Phys Med Biol. 2013 Oct 7;58(19):6683–6700.
Journal cover image

Published In

Phys Med Biol

DOI

EISSN

1361-6560

Publication Date

October 7, 2013

Volume

58

Issue

19

Start / End Page

6683 / 6700

Location

England

Related Subject Headings

  • Radiotherapy, Intensity-Modulated
  • Quality Control
  • Nuclear Medicine & Medical Imaging
  • Medical Errors
  • Electrical Equipment and Supplies
  • 5105 Medical and biological physics
  • 1103 Clinical Sciences
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences