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Image acquisition optimization of a limited-angle intrafraction verification (LIVE) system for lung radiotherapy.

Publication ,  Journal Article
Zhang, Y; Deng, X; Yin, F-F; Ren, L
Published in: Med Phys
January 2018

PURPOSE: Limited-angle intrafraction verification (LIVE) has been previously developed for four-dimensional (4D) intrafraction target verification either during arc delivery or between three-dimensional (3D)/IMRT beams. Preliminary studies showed that LIVE can accurately estimate the target volume using kV/MV projections acquired over orthogonal view 30° scan angles. Currently, the LIVE imaging acquisition requires slow gantry rotation and is not clinically optimized. The goal of this study is to optimize the image acquisition parameters of LIVE for different patient respiratory periods and gantry rotation speeds for the effective clinical implementation of the system. METHOD: Limited-angle intrafraction verification imaging acquisition was optimized using a digital anthropomorphic phantom (XCAT) with simulated respiratory periods varying from 3 s to 6 s and gantry rotation speeds varying from 1°/s to 6°/s. LIVE scanning time was optimized by minimizing the number of respiratory cycles needed for the four-dimensional scan, and imaging dose was optimized by minimizing the number of kV and MV projections needed for four-dimensional estimation. The estimation accuracy was evaluated by calculating both the center-of-mass-shift (COMS) and three-dimensional volume-percentage-difference (VPD) between the tumor in estimated images and the ground truth images. The robustness of LIVE was evaluated with varied respiratory patterns, tumor sizes, and tumor locations in XCAT simulation. A dynamic thoracic phantom (CIRS) was used to further validate the optimized imaging schemes from XCAT study with changes of respiratory patterns, tumor sizes, and imaging scanning directions. RESULTS: Respiratory periods, gantry rotation speeds, number of respiratory cycles scanned and number of kV/MV projections acquired were all positively correlated with the estimation accuracy of LIVE. Faster gantry rotation speed or longer respiratory period allowed less respiratory cycles to be scanned and less kV/MV projections to be acquired to estimate the target volume accurately. Regarding the scanning time minimization, for patient respiratory periods of 3-4 s, gantry rotation speeds of 1°/s, 2°/s, 3-6°/s required scanning of five, four, and three respiratory cycles, respectively. For patient respiratory periods of 5-6 s, the corresponding respiratory cycles required in the scan changed to four, three, and two cycles, respectively. Regarding the imaging dose minimization, for patient respiratory periods of 3-4 s, gantry rotation speeds of 1°/s, 2-4°/s, 5-6°/s required acquiring of 7, 5, 4 kV and MV projections, respectively. For patient respiratory periods of 5-6 s, 5 kV and 5 MV projections are sufficient for all gantry rotation speeds. The optimized LIVE system was robust against breathing pattern, tumor size and tumor location changes. In the CIRS study, the optimized LIVE system achieved the average center-of-mass-shift (COMS)/volume-percentage-difference (VPD) of 0.3 ± 0.1 mm/7.7 ± 2.0% for the scanning time priority case, 0.2 ± 0.1 mm/6.1 ± 1.2% for the imaging dose priority case, respectively, among all gantry rotation speeds tested. LIVE was robust against different scanning directions investigated. CONCLUSION: The LIVE system has been preliminarily optimized for different patient respiratory periods and treatment gantry rotation speeds using digital and physical phantoms. The optimized imaging parameters, including number of respiratory cycles scanned and kV/MV projection numbers acquired, provide guidelines for optimizing the scanning time and imaging dose of the LIVE system for its future evaluations and clinical implementations through patient studies.

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Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

January 2018

Volume

45

Issue

1

Start / End Page

340 / 351

Location

United States

Related Subject Headings

  • Tumor Burden
  • Respiration
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy, Image-Guided
  • Pilot Projects
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Motion
  • Models, Anatomic
  • Lung Neoplasms
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Zhang, Y., Deng, X., Yin, F.-F., & Ren, L. (2018). Image acquisition optimization of a limited-angle intrafraction verification (LIVE) system for lung radiotherapy. Med Phys, 45(1), 340–351. https://doi.org/10.1002/mp.12647
Zhang, Yawei, Xinchen Deng, Fang-Fang Yin, and Lei Ren. “Image acquisition optimization of a limited-angle intrafraction verification (LIVE) system for lung radiotherapy.Med Phys 45, no. 1 (January 2018): 340–51. https://doi.org/10.1002/mp.12647.
Zhang, Yawei, et al. “Image acquisition optimization of a limited-angle intrafraction verification (LIVE) system for lung radiotherapy.Med Phys, vol. 45, no. 1, Jan. 2018, pp. 340–51. Pubmed, doi:10.1002/mp.12647.

Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

January 2018

Volume

45

Issue

1

Start / End Page

340 / 351

Location

United States

Related Subject Headings

  • Tumor Burden
  • Respiration
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy, Image-Guided
  • Pilot Projects
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Motion
  • Models, Anatomic
  • Lung Neoplasms