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A novel total variation based ring artifact suppression method for CBCT imaging with two-dimensional antiscatter

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A new adaptive-diffusive total variation minimization (adTVM) method effectively suppresses ring artifacts in cone beam computed tomography (CBCT) images caused by two-dimensional antiscatter grids (2DASG). This technique improves image quality by reducing scatter and preserving accuracy.

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Area of Science:

  • Medical Imaging
  • Image Processing
  • Radiological Physics

Background:

  • Two-dimensional antiscatter grids (2DASG) are researched to enhance cone beam computed tomography (CBCT) image quality by reducing scatter.
  • Implementation challenges include septa shadows from 2DASGs, which can cause ring artifacts in CBCT images if uncorrected.

Purpose of the Study:

  • To present a novel method for suppressing ring artifacts in flat panel detector-based CBCT images.
  • Specifically, to address artifacts arising from 2DASG septa shadows.

Main Methods:

  • A total variation minimization (TVM) formulation, termed adaptive-diffusive total variation minimization (adTVM), was developed to suppress septa shadows.
  • The method adaptively adjusts the diffusivity regularization parameter based on local pixel gradients during iterative projection correction.
  • Projections were corrected using gantry angle-specific gain correction followed by the adTVM method before FDK reconstruction.

Main Results:

  • The adTVM method significantly reduced ring artifacts in CBCT images across three different 2DASG prototypes.
  • Observed improvements include a 7-74% reduction in the standard deviation of CT numbers and an 8-67% increase in contrast-to-noise ratio (CNR).
  • CT number accuracy for contrast objects was preserved.

Conclusions:

  • The proposed adTVM method effectively suppresses ring artifacts caused by 2DASG septa shadows in CBCT.
  • The method shows potential for enabling the use of 2DASGs in flat panel detector-based CBCT systems by preserving spatial resolution and CT number accuracy.