arXiv subjects

Nancy L Ford

Publications and source records attributed to Nancy L Ford.

3 recordsLinked to original sources

arXiv2026

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

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.

physics.med-ph↗

arXiv2026

Visualising Parker Weighting in Short-Scan Cone-Beam Micro-CT: A Practical Reference

Short-scan FDK reconstruction is widely used in preclinical cone-beam micro-CT because it reduces scan time and radiation dose, and because the large volume sizes typical of micro-CT make iterative methods impractical for routine use. Short scans, however, introduce non-uniform data redundancy that must be corrected by Parker weighting to avoid directional shading artefacts. This note provides a visual and quantitative summary of Parker weighting as implemented for the eXplore CT 120 scanner. We illustrate the weight maps in the detector and sinogram domains, demonstrate the shading artefacts that arise without correction on both an image quality phantom and an in vivo mouse lung, and show via MTF, NPS, and detectability analysis that Parker weighting corrects HU inaccuracies without degrading image quality. No new methods are introduced; the aim is to serve as a concise practical reference for groups implementing or evaluating short-scan FDK pipelines.

physics.med-ph↗

arXiv2026

Benchmarking Open-Source FDK Against Commercial and Iterative Reconstruction Methods for Preclinical Micro-CBCT

Preclinical micro-CT reconstruction involves large projection sizes and volumes that make iterative methods costly - 5x to 50x slower than analytic alternatives on modern GPUs. Whether this cost is justified depends on the imaging task, yet head-to-head comparisons using task-based metrics on identical preclinical data are lacking. We benchmark four reconstruction methods on identical acquisitions from an eXplore CT 120 micro-CT scanner (Trifoil Imaging, USA): an open-source Feldkamp-Davis-Kress (FDK) pipeline, the proprietary vendor software, and two iterative toolboxes at default settings - ASTRA SIRT and TIGRE OS-SART. Using the modulation transfer function (MTF), noise power spectrum (NPS), and non-prewhitening detectability index (NPW d'), we show that single-metric rankings are misleading: the vendor software achieves the highest spatial resolution ($\mathrm{MTF}_{10} = 2.96$ lp/mm) but fails to reach the Rose criterion ($d'=3$) for 100 HU contrast objects on a half-scan acquisition. ASTRA SIRT, at 5x the computation time of FDK, provides the best low-contrast detectability, while TIGRE OS-SART at 50x the cost offers no additional benefit and exhibits instability across scan protocols. For high-contrast tasks, all methods perform comparably. We release our FDK pipeline as open-source software, providing a fast, transparent, and integrable reconstruction tool for the preclinical micro-CT community.

physics.med-ph↗