Classical & Iterative Reconstruction
Classical CT reconstruction recovers an image from its line-integral projections with analytical inversion formulas or iterative optimisation, without learned components. Analytical methods, filtered back-projection (FBP) for parallel and fan beams and the Feldkamp-Davis-Kress (FDK) algorithm for cone beams, invert the Radon transform directly and remain the default in most scanners because they are fast and predictable.
Iterative methods treat reconstruction as solving a large linear system or an optimisation problem. Algebraic techniques (ART, SART, SIRT), statistical methods (maximum likelihood, penalised likelihood, model-based iterative reconstruction) and Krylov solvers such as CGLS model the scanner and the noise explicitly, which pays off when data are noisy or incomplete.
Regularisation is what lets iterative methods work with little data: total variation (TV) and its generalisations, wavelet and shearlet sparsity, dictionary learning and non-local penalties. Compressed sensing gave this a theoretical basis around 2006, and these solvers are still the data-consistency backbone inside many deep-learning methods.
Browse all 71 Classical & Iterative Reconstruction papers in the searchable directory
Start here
If you are new to this topic, these are good first reads, chosen by the maintainers.
- Über die Bestimmung von Funktionen durch ihre Integralwerte längs gewisser Mannigfaltigkeiten (Johann Radon) (Ber. Verh. Sächs. Akad. Wiss. Leipzig, Math.-Phys. Kl., 1917)
Defines the transform that every analytical CT method inverts. - Practical cone-beam algorithm (JOSA A, 1984)
The approximate cone-beam algorithm that most CBCT systems still use. - Simultaneous Algebraic Reconstruction Technique (SART): A superior implementation of the ART algorithm (Ultrasonic Imaging, 1984)
The simultaneous algebraic reconstruction technique, a standard iterative baseline implemented in most open toolkits. - Image reconstruction in circular cone-beam computed tomography by constrained, total-variation minimization (PMB, 2008)
The TV-constrained ASD-POCS algorithm that made compressed-sensing CT practical for few-view cone-beam data. - The Evolution of Image Reconstruction for CT: From Filtered Back Projection to Artificial Intelligence (Eur Radiol, 2019)
A clinically oriented review of the path from FBP through iterative reconstruction to AI.
Papers
The 30 most recent of 71 papers, newest first.
Browse all 71 Classical & Iterative Reconstruction papers in the searchable directory
Datasets, benchmarks and toolkits
Entries from the directory whose tasks or tags match this topic.
- Walnut-CBCT (official page) · Dataset — Projection only. Finnish Inverse Problems Society. Real cone-beam projections of a walnut at several angular samplings — a standard test bed for sparse-view and limited-angle CBCT.
- Finnish Inverse Problems Society (FIPS) datasets (official page) · Dataset — Projection only. A family of real measured sinograms (walnut, lotus root, apple, carrot, phantoms) with carefully documented acquisition geometry — the cleanest public source for testing reconstruction operators.
- SparseBeads (official page) · Dataset — Projection + image. 48 measured scans of bead phantoms whose image sparsity varies systematically, released specifically as a benchmark for sparsity-regularised reconstruction.
- TIGRE · Toolkit — GPU-accelerated (CUDA) toolbox for cone-beam and parallel-beam CT; FDK, SART, SIRT, CGLS and TV variants.
- ASTRA Toolbox · Toolkit — Long-standing research toolbox with a large set of projectors and algorithms; the reference CPU/GPU baseline.
- ODL · Toolkit — Operator Discretization Library — a functional-analytic framework for inverse problems, with CT geometries built in.
- Core Imaging Library (CIL) · Toolkit — CCPi framework for variational CT reconstruction with a large catalogue of optimisation algorithms.
- CCPi Regularisation Toolkit · Toolkit — CPU/GPU implementations of TV, TGV, directional TV and other regularisers used by CIL.
- LEAP · Toolkit — LLNL's LivermorE AI Projector for Computed Tomography (LEAP); production-grade model-based iterative reconstruction for 3D transmission CT.
- svmbir · Toolkit — Fast Super-Voxel Model Based Iterative Reconstruction with proximal-map plug-ins.
- RTK · Toolkit — Reconstruction Toolkit built on ITK; widely used in clinical CBCT and interventional research.
- OMEGA · Toolkit — Open-source multi-dimensional tomographic reconstruction software covering PET/SPECT/CT.
- TomoPy · Toolkit — Reference toolkit for synchrotron micro/nano tomography; gridrec, FBP and phase retrieval.
- pySART · Toolkit — Compact reference implementation of the Simultaneous Algebraic Reconstruction Technique.
- libcbct · Toolkit — Lightweight cone-beam CT reconstruction library with FDK and iterative solvers; non-commercial licence.
- sigpy · Toolkit — Signal-processing package for iterative image reconstruction; proximal operators and NUFFT primitives.
- MIRT · Toolkit — Michigan Image Reconstruction Toolbox. Reference implementations of a very wide range of classical, statistical and penalised-likelihood reconstruction methods; the Julia port of the long-standing MATLAB MIRT.
- IRtools · Toolkit — Iterative Regularization Tools — hybrid Krylov methods, Tikhonov, TV and general-form regularisation, shipped with large-scale tomography test problems. From Hansen's group.
- leehoy/CTReconstruction · Toolkit — Compact, readable Python and MATLAB CT reconstruction code. FBP plus ASD-POCS, SART and EM already exist under python/, though the README still lists iterative reconstruction as "to be added".
- DBT-Reconstruction · Toolkit — Open-source reconstruction toolbox for digital breast tomosynthesis, covering DBT-specific geometry alongside FBP and iterative solvers.
- DIRECTT Reconstruction GUI · Toolkit — A Python GUI built on the ASTRA toolbox for reconstructing X-ray CT data, with the DIRECTT algorithm included.
- CTrex · Toolkit — A research-oriented GPU iterative reconstruction framework that exposes the projection–correction–backprojection pipeline all the way down to the individual CUDA kernels, so non-ideal acquisition effects can be folded into the operators…
Guides
Guides that cover this topic.
Other topics
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- Sparse-View CT (157)
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- Low-Dose CT Denoising (69)
- Metal Artifact Reduction (23)
- Spectral & Dual-Energy CT (19)
- Cone-Beam CT (77)
- Dynamic & 4D CT (24)
- Scatter Correction (11)
- Geometry Calibration & Motion Compensation (28)
- Deep Unrolling & Model-Based Learning (68)
- Self-Supervised & Untrained Methods (35)
- Diffusion & Generative Priors (68)
- Implicit Neural Representations (25)
- Gaussian Splatting (26)