Welcome to FreeCT!

FreeCT is a free software project for the reconstruction of 3rd generation, helical CT projection data. We currently offer FreeCT_wFBP, a GPU-focused implementation of weighted filtered backprojection, intended for fast, flexible, scanner-independent reconstruction of simulated or clinical data using modern, analytic reconstruction methods. FreeCT_wFBP is available under the GNU GPL v2.0.


FreeCT is written in C and utilizes the NVIDIA CUDA framework for GPU execution. It is designed to be fast, lightweight, require a minimal number third-party libraries (currently only FFTW3 and the CUDA toolkit), and be easy to use and customize for research and education.


FreeCT_wFBP currently supports the following:

  • 3rd-generation CT geometry
  • Helical acquisition
  • Flying focal spots
  • Quarter detector offset
  • User-definable scanner geometry
  • User-modifiable reconstruction kernels
  • Text-based parameter files for configuration
  • GPU+CPU and CPU-only modes


An overview of FreeCT_wFBP and some benchmarking has been published as a technical note in Medical Physics:


FreeCT_wFBP is an implementation of the algorithms outlined in the following two papers:


To get reconstructing using FreeCT_wFBP, check out the "Getting Started" page. Be sure and also check out the documentation for more details.


Thanks for your interest in FreeCT!

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