The influence of bowtie filtration on cone-beam CT image quality

N. Mail, D. J. Moseley, J. H. Siewerdsen, D. A. Jaffray

Research output: Contribution to journalArticlepeer-review

Abstract

The large variation of x-ray fluence at the detector in cone-beam CT (CBCT) poses a significant challenge to detectors' limited dynamic range, resulting in the loss of skinline as well as reduction of CT number accuracy, contrast-to-noise ratio, and image uniformity. The authors investigate the performance of a bowtie filter implemented in a system for image-guided radiation therapy (Elekta oncology system, XVI) as a compensator for improved image quality through fluence modulation, reduction in x-ray scatter, and reduction in patient dose. Dose measurements with and without the bowtie filter were performed on a CTDI Dose phantom and an empirical fit was made to calculate dose for any radial distance from the central axis of the phantom. Regardless of patient size, shape, anatomical site, and field of view, the bowtie filter results in an overall improvement in CT number accuracy, image uniformity, low-contrast detectability, and imaging dose. The implemented bowtie filter offers a significant improvement in imaging performance and is compatible with the current clinical system for image-guided radiation therapy.

Original languageEnglish (US)
Pages (from-to)22-32
Number of pages11
JournalMedical physics
Volume36
Issue number1
DOIs
StatePublished - 2009
Externally publishedYes

Keywords

  • Bowtie filter
  • Dose
  • Elekta synergy CBCT system
  • Image quality

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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