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A novel technique for markerless, self-sorted 4D-CBCT: feasibility study.

Publication ,  Journal Article
Vergalasova, I; Cai, J; Yin, F-F
Published in: Med Phys
March 2012

PURPOSE: Four-dimensional CBCT (4D-CBCT) imaging in the treatment room can provide verification of moving targets, facilitating the potential for margin reduction and consequent dose escalation. Reconstruction of 4D-CBCT images requires correlation of respiratory phase with projection acquisition, which is often achieved with external surrogate measures of respiration. However, external measures may not be a direct representation of the motion of the internal anatomy and it is therefore the aim of this work to develop a novel technique for markerless, self-sorted 4D-CBCT reconstruction. METHODS: A novel 4D-CBCT reconstruction technique based on the principles of Fourier transform (FT) theory was investigated for markerless extraction of respiratory phase directly from projection data. In this FT technique, both phase information (FT-phase) and magnitude information (FT-magnitude) were separately implemented in order to discern projections corresponding to peak inspiration, which then facilitated the proceeding sort and bin processes involved in retrospective 4D image reconstruction. In order to quantitatively evaluate the accuracy of the Fourier methods, peak-inspiration projections identified each by FT-phase and FT-magnitude were compared to those manually identified by visual tracking of structures. The average phase difference as assigned by each method vs the manual technique was calculated per projection dataset. The percentage of projections that were assigned within 10% phase of each other was also computed. Both Fourier methods were tested on two phantom datasets, programmed to exhibit sinusoidal respiratory cycles of 2.0 cm in amplitude with respiratory cycle lengths of 3 and 6 s, respectively. Additionally, three sets of patient projections were studied. All of the data were previously acquired at slow-gantry speeds ranging between 0.6°/s and 0.7°/s over a 200° rotation. Ten phase bins with 10% phase windows were selected for 4D-CBCT reconstruction of one phantom and one patient case for visual and quantitative comparison. Line profiles were plotted for the 0% and 50% phase images as reconstructed by the manual technique and each of the Fourier methods. RESULTS: As compared with the manual technique, the FT-phase method resulted in average phase differences of 1.8% for the phantom with the 3 s respiratory cycle, 3.9% for the phantom with the 6 s respiratory cycle, 2.9% for patient 1, 5.0% for patient 2, and 3.8% for patient 3. For the FT-magnitude method, these numbers were 2.1%, 4.0%, 2.9%, 5.3%, and 3.5%, respectively. The percentage of projections that were assigned within 10% phase by the FT-phase method as compared to the manual technique for the five datasets were 100.0%, 100.0%, 97.6%, 93.4%, and 94.1%, respectively, whereas for the FT-magnitude method these percentages were 98.1%, 92.3%, 98.7%, 87.3%, and 95.7%. Reconstructed 4D phase images for both the phantom and patient case were visually and quantitatively equivalent between each of the Fourier methods vs the manual technique. CONCLUSIONS: A novel technique employing the basics of Fourier transform theory was investigated and demonstrated to be feasible in achieving markerless, self-sorted 4D-CBCT reconstruction.

Duke Scholars

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

March 2012

Volume

39

Issue

3

Start / End Page

1442 / 1451

Location

United States

Related Subject Headings

  • Respiration
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Imaging, Three-Dimensional
  • Humans
  • Feasibility Studies
  • Cone-Beam Computed Tomography
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
 

Citation

APA
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ICMJE
MLA
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Vergalasova, I., Cai, J., & Yin, F.-F. (2012). A novel technique for markerless, self-sorted 4D-CBCT: feasibility study. Med Phys, 39(3), 1442–1451. https://doi.org/10.1118/1.3685443
Vergalasova, Irina, Jing Cai, and Fang-Fang Yin. “A novel technique for markerless, self-sorted 4D-CBCT: feasibility study.Med Phys 39, no. 3 (March 2012): 1442–51. https://doi.org/10.1118/1.3685443.
Vergalasova I, Cai J, Yin F-F. A novel technique for markerless, self-sorted 4D-CBCT: feasibility study. Med Phys. 2012 Mar;39(3):1442–51.
Vergalasova, Irina, et al. “A novel technique for markerless, self-sorted 4D-CBCT: feasibility study.Med Phys, vol. 39, no. 3, Mar. 2012, pp. 1442–51. Pubmed, doi:10.1118/1.3685443.
Vergalasova I, Cai J, Yin F-F. A novel technique for markerless, self-sorted 4D-CBCT: feasibility study. Med Phys. 2012 Mar;39(3):1442–1451.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

March 2012

Volume

39

Issue

3

Start / End Page

1442 / 1451

Location

United States

Related Subject Headings

  • Respiration
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Imaging, Three-Dimensional
  • Humans
  • Feasibility Studies
  • Cone-Beam Computed Tomography
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis