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Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging.

Publication ,  Journal Article
Luo, W; Yoo, S; Wu, QJ; Wang, Z; Yin, F-F
Published in: Med Phys
December 2008

Real-time tracking can provide high accuracy localization for a moving target and minimize the effect of motion. Simultaneous kV-MV imaging has been proposed as a real-time tracking technique by utilizing the existing kV on-board imager (OBI) and the MV electronic portal device (EPID) mounted on the linear accelerator. The orthogonal pair of kV-MV images acquired simultaneously can provide 3-D localization in real-time. However, the kV and MV beams cross shooting the target interfere with each other with beam scattering, which affects the quality of images. The success of this modality heavily relies on the image quality, especially the visibility of the target, which was investigated in this study. The kV and MV images were acquired for a gold implant marker that was used as a surrogate of the target and placed in an IMRT thorax phantom, a dynamic phantom, and a pelvis phantom to test the image quality in different situations. Contrast-to-noise ration (CNR) was used to quantitatively describe the visibility of the target in the image. CNR can be obtained by statistical calculation from image processing and physics analysis with ion chamber measurement. The difference is described by contrast detection efficiency (CDE). By comparing the ratio (R) of CNR with and without the MV beam on, the MV beam scatter was found to have dramatically reduced the target visibility in the kV images (R=0.47), which was supported by an independent physics analysis that treats beam scatter as a noise. In contrast, the kV scatter effect on the MV images was minor (R=0.93). The effect of tumor motion was visible but tolerable for the target tracking purpose. CNR varied with different tumor sites and was lower for the pelvis than the thorax. Different kV imaging parameters such as kVp, mAs, and exposure time ms were tested for different cases. Considering a threshold of 1.0 CNR as a measure for the target visibility, a range of CNR from 1.3 to 4.2 was reached with appropriate tuning of those imaging parameters. This study has shown that CNR is a key parameter that can be used for assessing the visibility of the target in digital imaging and the quality of kV/MV images. It has also been shown that reasonable target visibility can be obtained using simultaneous kV-MV imaging for real-time target tracking.

Duke Scholars

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

December 2008

Volume

35

Issue

12

Start / End Page

5501 / 5509

Location

United States

Related Subject Headings

  • Time Factors
  • Software
  • Scattering, Radiation
  • Radiography, Thoracic
  • Radiography
  • Photons
  • Phantoms, Imaging
  • Pelvis
  • Particle Accelerators
  • Nuclear Medicine & Medical Imaging
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Luo, W., Yoo, S., Wu, Q. J., Wang, Z., & Yin, F.-F. (2008). Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging. Med Phys, 35(12), 5501–5509. https://doi.org/10.1118/1.3002313
Luo, W., S. Yoo, Q. J. Wu, Z. Wang, and F. -. F. Yin. “Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging.Med Phys 35, no. 12 (December 2008): 5501–9. https://doi.org/10.1118/1.3002313.
Luo W, Yoo S, Wu QJ, Wang Z, Yin F-F. Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging. Med Phys. 2008 Dec;35(12):5501–9.
Luo, W., et al. “Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging.Med Phys, vol. 35, no. 12, Dec. 2008, pp. 5501–09. Pubmed, doi:10.1118/1.3002313.
Luo W, Yoo S, Wu QJ, Wang Z, Yin F-F. Analysis of image quality for real-time target tracking using simultaneous kV-MV imaging. Med Phys. 2008 Dec;35(12):5501–5509.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

December 2008

Volume

35

Issue

12

Start / End Page

5501 / 5509

Location

United States

Related Subject Headings

  • Time Factors
  • Software
  • Scattering, Radiation
  • Radiography, Thoracic
  • Radiography
  • Photons
  • Phantoms, Imaging
  • Pelvis
  • Particle Accelerators
  • Nuclear Medicine & Medical Imaging