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Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy.

Publication ,  Journal Article
Zhang, Y; Yin, F-F; Zhang, Y; Ren, L
Published in: Phys Med Biol
May 7, 2017

The purpose of this study is to develop an adaptive prior knowledge guided image estimation technique to reduce the scan angle needed in the limited-angle intrafraction verification (LIVE) system for 4D-CBCT reconstruction. The LIVE system has been previously developed to reconstruct 4D volumetric images on-the-fly during arc treatment for intrafraction target verification and dose calculation. In this study, we developed an adaptive constrained free-form deformation reconstruction technique in LIVE to further reduce the scanning angle needed to reconstruct the 4D-CBCT images for faster intrafraction verification. This technique uses free form deformation with energy minimization to deform prior images to estimate 4D-CBCT based on kV-MV projections acquired in extremely limited angle (orthogonal 3°) during the treatment. Note that the prior images are adaptively updated using the latest CBCT images reconstructed by LIVE during treatment to utilize the continuity of the respiratory motion. The 4D digital extended-cardiac-torso (XCAT) phantom and a CIRS 008A dynamic thoracic phantom were used to evaluate the effectiveness of this technique. The reconstruction accuracy of the technique was evaluated by calculating both the center-of-mass-shift (COMS) and 3D volume-percentage-difference (VPD) of the tumor in reconstructed images and the true on-board images. The performance of the technique was also assessed with varied breathing signals against scanning angle, lesion size, lesion location, projection sampling interval, and scanning direction. In the XCAT study, using orthogonal-view of 3° kV and portal MV projections, this technique achieved an average tumor COMS/VPD of 0.4  ±  0.1 mm/5.5  ±  2.2%, 0.6  ±  0.3 mm/7.2  ±  2.8%, 0.5  ±  0.2 mm/7.1  ±  2.6%, 0.6  ±  0.2 mm/8.3  ±  2.4%, for baseline drift, amplitude variation, phase shift, and patient breathing signal variation, respectively. In the CIRS phantom study, this technique achieved an average tumor COMS/VPD of 0.7  ±  0.1 mm/7.5  ±  1.3% for a 3 cm lesion and 0.6  ±  0.2 mm/11.4  ±  1.5% for a 2 cm lesion in the baseline drift case. The average tumor COMS/VPD were 0.5  ±  0.2 mm/10.8  ±  1.4%, 0.4  ±  0.3 mm/7.3  ±  2.9%, 0.4  ±  0.2 mm/7.4  ±  2.5%, 0.4  ±  0.2 mm/7.3  ±  2.8% for the four real patient breathing signals, respectively. Results demonstrated that the adaptive prior knowledge guided image estimation technique with LIVE system is robust against scanning angle, lesion size, location and scanning direction. It can estimate on-board images accurately with as little as 6 projections in orthogonal-view 3° angle. In conclusion, adaptive prior knowledge guided image reconstruction technique accurately estimates 4D-CBCT images using extremely-limited angle and projections. This technique greatly improves the efficiency and accuracy of LIVE system for ultrafast 4D intrafraction verification of lung SBRT treatments.

Duke Scholars

Published In

Phys Med Biol

DOI

EISSN

1361-6560

Publication Date

May 7, 2017

Volume

62

Issue

9

Start / End Page

3859 / 3882

Location

England

Related Subject Headings

  • Respiration
  • Radiotherapy, Conformal
  • Radiotherapy Planning, Computer-Assisted
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Motion
  • Lung Neoplasms
  • Humans
  • Four-Dimensional Computed Tomography
  • Cone-Beam Computed Tomography
 

Citation

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Zhang, Y., Yin, F.-F., & Ren, L. (2017). Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy. Phys Med Biol, 62(9), 3859–3882. https://doi.org/10.1088/1361-6560/aa6913
Zhang, Yawei, Fang-Fang Yin, You Zhang, and Lei Ren. “Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy.Phys Med Biol 62, no. 9 (May 7, 2017): 3859–82. https://doi.org/10.1088/1361-6560/aa6913.
Zhang, Yawei, et al. “Reducing scan angle using adaptive prior knowledge for a limited-angle intrafraction verification (LIVE) system for conformal arc radiotherapy.Phys Med Biol, vol. 62, no. 9, May 2017, pp. 3859–82. Pubmed, doi:10.1088/1361-6560/aa6913.
Journal cover image

Published In

Phys Med Biol

DOI

EISSN

1361-6560

Publication Date

May 7, 2017

Volume

62

Issue

9

Start / End Page

3859 / 3882

Location

England

Related Subject Headings

  • Respiration
  • Radiotherapy, Conformal
  • Radiotherapy Planning, Computer-Assisted
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Motion
  • Lung Neoplasms
  • Humans
  • Four-Dimensional Computed Tomography
  • Cone-Beam Computed Tomography