An empirical method for lag correction in cone-beam CT

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

Research output: Contribution to journalArticle

Abstract

Image lag degrades image quality in cone-beam CT (CBCT), resulting in contrast reduction, lack of CT number accuracy and uniformity, and skin-line artifacts. The magnitude of such degradation and the extent to which imaging performance can be improved by means of a lag correction method were investigated. Measurements were performed using a radiotherapy CBCT guidance system (Elekta Synergy XVI, Elekta Oncology Systems, Atlanta, GA), for which the imaging system is based upon a RID1640-AL1 flat-panel imager (Perkin Elmer, Wiesbaden, Germany). Image lag and its relationship to various parameters including signal magnitude, photon energy, and frame number were investigated, and an empirical lag correction method was developed to manage lag artifacts. The correction method was simply the subtraction from the current frame by previous frames weighted by the temporal response function. The CatPhan 500 phantom (The Phantom Laboratory, Salem, NY) within an irregularly shaped body annulus was used to demonstrate the magnitude of artifacts with and without lag correction. CBCT images after correction demonstrated improvement in skin-line reconstruction, CT number accuracy, image uniformity, and contrast-to-noise ratio. Lag artifacts can be reduced by means of algorithmic correction of the projection images. Lag correction is most important for all shapes of objects having contrast inserts. For circular/cylindrical objects, lag correction does not improve the skin-line artifact but can improve low contrast visibility adjacent to high contrast objects.

Original languageEnglish (US)
Pages (from-to)5187-5196
Number of pages10
JournalMedical Physics
Volume35
Issue number11
DOIs
StatePublished - 2008
Externally publishedYes

Fingerprint

Artifacts
Cone-Beam Computed Tomography
Skin
Photons
Germany
Noise
Radiotherapy

Keywords

  • Cone-beam CT
  • Flat-panel imager
  • Ghosting
  • Image lag
  • Lag correction

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

An empirical method for lag correction in cone-beam CT. / Mail, N.; Moseley, D. J.; Siewerdsen, Jeff; Jaffray, D. A.

In: Medical Physics, Vol. 35, No. 11, 2008, p. 5187-5196.

Research output: Contribution to journalArticle

Mail, N, Moseley, DJ, Siewerdsen, J & Jaffray, DA 2008, 'An empirical method for lag correction in cone-beam CT', Medical Physics, vol. 35, no. 11, pp. 5187-5196. https://doi.org/10.1118/1.2977759
Mail, N. ; Moseley, D. J. ; Siewerdsen, Jeff ; Jaffray, D. A. / An empirical method for lag correction in cone-beam CT. In: Medical Physics. 2008 ; Vol. 35, No. 11. pp. 5187-5196.
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