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Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs.

Publication ,  Journal Article
Li, H; Giles, W; Ren, L; Bowsher, J; Yin, F-F
Published in: Med Phys
October 2012

PURPOSE: To implement dual-energy imaging technique for virtual monochromatic (VM) and linearly mixed (LM) cone beam CTs (CBCTs) and to demonstrate their potential applications in metal artifact reduction and contrast enhancement in image-guided radiation therapy (IGRT). METHODS: A bench-top CBCT system was used to acquire 80 kVp and 150 kVp projections, with an additional 0.8 mm tin filtration. To implement the VM technique, these projections were first decomposed into acrylic and aluminum basis material projections to synthesize VM projections, which were then used to reconstruct VM CBCTs. The effect of VM CBCT on the metal artifact reduction was evaluated with an in-house titanium-BB phantom. The optimal VM energy to maximize contrast-to-noise ratio (CNR) for iodine contrast and minimize beam hardening in VM CBCT was determined using a water phantom containing two iodine concentrations. The LM technique was implemented by linearly combining the low-energy (80 kVp) and high-energy (150 kVp) CBCTs. The dose partitioning between low-energy and high-energy CBCTs was varied (20%, 40%, 60%, and 80% for low-energy) while keeping total dose approximately equal to single-energy CBCTs, measured using an ion chamber. Noise levels and CNRs for four tissue types were investigated for dual-energy LM CBCTs in comparison with single-energy CBCTs at 80, 100, 125, and 150 kVp. RESULTS: The VM technique showed substantial reduction of metal artifacts at 100 keV with a 40% reduction in the background standard deviation compared to a 125 kVp single-energy scan of equal dose. The VM energy to maximize CNR for both iodine concentrations and minimize beam hardening in the metal-free object was 50 keV and 60 keV, respectively. The difference of average noise levels measured in the phantom background was 1.2% between dual-energy LM CBCTs and equivalent-dose single-energy CBCTs. CNR values in the LM CBCTs of any dose partitioning are better than those of 150 kVp single-energy CBCTs. The average CNR for four tissue types with 80% dose fraction at low-energy showed 9.0% and 4.1% improvement relative to 100 kVp and 125 kVp single-energy CBCTs, respectively. CNRs for low-contrast objects improved as dose partitioning was more heavily weighted toward low-energy (80 kVp) for LM CBCTs. CONCLUSIONS: Dual-energy CBCT imaging techniques were implemented to synthesize VM CBCT and LM CBCTs. VM CBCT was effective at achieving metal artifact reduction. Depending on the dose-partitioning scheme, LM CBCT demonstrated the potential to improve CNR for low contrast objects compared to single-energy CBCT acquired with equivalent dose.

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Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

October 2012

Volume

39

Issue

10

Start / End Page

6056 / 6064

Location

United States

Related Subject Headings

  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Cone-Beam Computed Tomography
  • Calibration
  • Artifacts
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Li, H., Giles, W., Ren, L., Bowsher, J., & Yin, F.-F. (2012). Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs. Med Phys, 39(10), 6056–6064. https://doi.org/10.1118/1.4752212
Li, Hao, William Giles, Lei Ren, James Bowsher, and Fang-Fang Yin. “Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs.Med Phys 39, no. 10 (October 2012): 6056–64. https://doi.org/10.1118/1.4752212.
Li H, Giles W, Ren L, Bowsher J, Yin F-F. Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs. Med Phys. 2012 Oct;39(10):6056–64.
Li, Hao, et al. “Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs.Med Phys, vol. 39, no. 10, Oct. 2012, pp. 6056–64. Pubmed, doi:10.1118/1.4752212.
Li H, Giles W, Ren L, Bowsher J, Yin F-F. Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs. Med Phys. 2012 Oct;39(10):6056–6064.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

October 2012

Volume

39

Issue

10

Start / End Page

6056 / 6064

Location

United States

Related Subject Headings

  • Radiation Dosage
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Cone-Beam Computed Tomography
  • Calibration
  • Artifacts
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering