Skip to main content

A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections.

Publication ,  Journal Article
Zhang, Y; Yin, F-F; Segars, WP; Ren, L
Published in: Med Phys
December 2013

PURPOSE: To develop a technique to estimate onboard 4D-CBCT using prior information and limited-angle projections for potential 4D target verification of lung radiotherapy. METHODS: Each phase of onboard 4D-CBCT is considered as a deformation from one selected phase (prior volume) of the planning 4D-CT. The deformation field maps (DFMs) are solved using a motion modeling and free-form deformation (MM-FD) technique. In the MM-FD technique, the DFMs are estimated using a motion model which is extracted from planning 4D-CT based on principal component analysis (PCA). The motion model parameters are optimized by matching the digitally reconstructed radiographs of the deformed volumes to the limited-angle onboard projections (data fidelity constraint). Afterward, the estimated DFMs are fine-tuned using a FD model based on data fidelity constraint and deformation energy minimization. The 4D digital extended-cardiac-torso phantom was used to evaluate the MM-FD technique. A lung patient with a 30 mm diameter lesion was simulated with various anatomical and respirational changes from planning 4D-CT to onboard volume, including changes of respiration amplitude, lesion size and lesion average-position, and phase shift between lesion and body respiratory cycle. The lesions were contoured in both the estimated and "ground-truth" onboard 4D-CBCT for comparison. 3D volume percentage-difference (VPD) and center-of-mass shift (COMS) were calculated to evaluate the estimation accuracy of three techniques: MM-FD, MM-only, and FD-only. Different onboard projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy. RESULTS: For all simulated patient and projection acquisition scenarios, the mean VPD (±S.D.)∕COMS (±S.D.) between lesions in prior images and "ground-truth" onboard images were 136.11% (±42.76%)∕15.5 mm (±3.9 mm). Using orthogonal-view 15°-each scan angle, the mean VPD∕COMS between the lesion in estimated and "ground-truth" onboard images for MM-only, FD-only, and MM-FD techniques were 60.10% (±27.17%)∕4.9 mm (±3.0 mm), 96.07% (±31.48%)∕12.1 mm (±3.9 mm) and 11.45% (±9.37%)∕1.3 mm (±1.3 mm), respectively. For orthogonal-view 30°-each scan angle, the corresponding results were 59.16% (±26.66%)∕4.9 mm (±3.0 mm), 75.98% (±27.21%)∕9.9 mm (±4.0 mm), and 5.22% (±2.12%)∕0.5 mm (±0.4 mm). For single-view scan angles of 3°, 30°, and 60°, the results for MM-FD technique were 32.77% (±17.87%)∕3.2 mm (±2.2 mm), 24.57% (±18.18%)∕2.9 mm (±2.0 mm), and 10.48% (±9.50%)∕1.1 mm (±1.3 mm), respectively. For projection angular-sampling-intervals of 0.6°, 1.2°, and 2.5° with the orthogonal-view 30°-each scan angle, the MM-FD technique generated similar VPD (maximum deviation 2.91%) and COMS (maximum deviation 0.6 mm), while sparser sampling yielded larger VPD∕COMS. With equal number of projections, the estimation results using scattered 360° scan angle were slightly better than those using orthogonal-view 30°-each scan angle. The estimation accuracy of MM-FD technique declined as noise level increased. CONCLUSIONS: The MM-FD technique substantially improves the estimation accuracy for onboard 4D-CBCT using prior planning 4D-CT and limited-angle projections, compared to the MM-only and FD-only techniques. It can potentially be used for the inter/intrafractional 4D-localization verification.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

December 2013

Volume

40

Issue

12

Start / End Page

121701

Location

United States

Related Subject Headings

  • Radiotherapy, Image-Guided
  • Principal Component Analysis
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Movement
  • Models, Biological
  • Lung Neoplasms
  • Humans
  • Four-Dimensional Computed Tomography
  • Cone-Beam Computed Tomography
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Zhang, Y., Yin, F.-F., Segars, W. P., & Ren, L. (2013). A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections. Med Phys, 40(12), 121701. https://doi.org/10.1118/1.4825097
Zhang, You, Fang-Fang Yin, W Paul Segars, and Lei Ren. “A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections.Med Phys 40, no. 12 (December 2013): 121701. https://doi.org/10.1118/1.4825097.
Zhang Y, Yin F-F, Segars WP, Ren L. A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections. Med Phys. 2013 Dec;40(12):121701.
Zhang, You, et al. “A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections.Med Phys, vol. 40, no. 12, Dec. 2013, p. 121701. Pubmed, doi:10.1118/1.4825097.
Zhang Y, Yin F-F, Segars WP, Ren L. A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections. Med Phys. 2013 Dec;40(12):121701.

Published In

Med Phys

DOI

EISSN

2473-4209

Publication Date

December 2013

Volume

40

Issue

12

Start / End Page

121701

Location

United States

Related Subject Headings

  • Radiotherapy, Image-Guided
  • Principal Component Analysis
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Movement
  • Models, Biological
  • Lung Neoplasms
  • Humans
  • Four-Dimensional Computed Tomography
  • Cone-Beam Computed Tomography