Skip to main content

TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT

Publication ,  Conference
Giles, W; Bowsher, J; Yin, F
Published in: Medical Physics
January 1, 2010

Purpose: Large dark and bright crescents are commonly seen in cone‐beam (CB) CT images acquired onboard radiation therapy machines. The purpose of this project is to develop a technique for removing this artifact. Method and Materials: We propose that crescent artifacts are caused by small angle‐dependent shifts of the bowtie filter and that they can be avoided by using angle‐dependent blank projections when reconstructing CBCT images. Blank projections are those acquired without an attenuating object in the field of view. Bowtie motion as a function of angle was quantified by tracking the center of mass of pixel intensity in blank projections. Computer simulations were used to demonstrate that crescent artifacts arise under that quantified level of bowtie motion. Clinical onboard scanner studies with a Catphan® 504 phantom were used to demonstrate that crescent artifacts are removed by incorporating angle‐dependent, rather than fixed, blank projections into image reconstruction. Results: The center of mass study indicated that crescent artifacts result from shifts in the bowtie filter of much less than 1 mm. The computer‐simulation studies demonstrated crescent artifacts when the same blank image was used for all projection angles. These crescent artifacts matched the positions, widths, and amplitudes of those seen clinically. In the computer‐simulation studies and with data acquired on clinical CBCT systems, the artifacts were removed when angle‐dependent blank images were utilized. Conclusion: Crescent artifacts are shown to arise from unaccounted motion of the bowtie filter during the acquisition of CBCT projections. Correction of this artifact, through use of angle‐dependent blank images, is proposed and demonstrated. This technique could be effectively implemented into clinical practice. Conflict of Interest: This research is partly supported by Varian Medical Systems. © 2010, American Association of Physicists in Medicine. All rights reserved.

Duke Scholars

Published In

Medical Physics

DOI

ISSN

0094-2405

Publication Date

January 1, 2010

Volume

37

Issue

6

Start / End Page

3370

Related Subject Headings

  • Nuclear Medicine & Medical Imaging
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Giles, W., Bowsher, J., & Yin, F. (2010). TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT. In Medical Physics (Vol. 37, p. 3370). https://doi.org/10.1118/1.3469171
Giles, W., J. Bowsher, and F. Yin. “TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT.” In Medical Physics, 37:3370, 2010. https://doi.org/10.1118/1.3469171.
Giles W, Bowsher J, Yin F. TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT. In: Medical Physics. 2010. p. 3370.
Giles, W., et al. “TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT.” Medical Physics, vol. 37, no. 6, 2010, p. 3370. Scopus, doi:10.1118/1.3469171.
Giles W, Bowsher J, Yin F. TU‐A‐204B‐04: A Technique to Correct Crescent Artifacts in On‐Board CBCT. Medical Physics. 2010. p. 3370.

Published In

Medical Physics

DOI

ISSN

0094-2405

Publication Date

January 1, 2010

Volume

37

Issue

6

Start / End Page

3370

Related Subject Headings

  • Nuclear Medicine & Medical Imaging
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
  • 1112 Oncology and Carcinogenesis
  • 0903 Biomedical Engineering
  • 0299 Other Physical Sciences