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arXiv · 2605.00239

Resolution-Noise Characteristics of Common FDK Filter Kernels: A Practical Reference for Preclinical Cone-Beam Micro-CT

Falk L Wiegmann·Nancy L Ford
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Abstract

The ramp filter kernel and cutoff frequency are fundamental parameters of the Feldkamp-Davis-Kress (FDK) algorithm that determine the resolution and noise characteristics of the reconstructed image. Despite their importance, systematic evaluations of their combined effect on task-based image quality in preclinical micro-CT are scarce, and many studies do not report the filter configuration used. We reconstruct identical data from a GE eXplore CT 120 scanner using four filter kernels (ramp, Shepp-Logan, cosine, Hamming) at four cutoff frequencies (1.0, 0.8, 0.6, and $0.379\times$ Nyquist, matched to the detector-to-voxel size ratio) and evaluate each of the sixteen configurations using the modulation transfer function (MTF), noise power spectrum (NPS), and non-prewhitening detectability index (NPW $d'$). Qualitative assessment is performed on a mouse lung specimen. Across the sixteen configurations, $\mathrm{MTF}_{10}$ ranges from 0.93 to 2.35 lp/mm, integrated NPS from 75,670 to 13,259 $\mathrm{HU}^2$, and the Rose criterion crossing diameter from 2.86 to 0.93 mm at $\Delta C = 500$ HU and from 7.74 to 3.62 mm at 100 HU. This note presents the data as a concise visual and quantitative reference for groups selecting FDK filter parameters for preclinical cone-beam CT.

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Falk L Wiegmann, Nancy L Ford. 2026-04-30. Resolution-Noise Characteristics of Common FDK Filter Kernels: A Practical Reference for Preclinical Cone-Beam Micro-CT. https://doi.org/10.1371/journal.pone.0349360

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