OSCaR
(Open Source Cone-beam Reconstructions) is a GUI (Graphical User Interface) developed for computing
three-dimensional
reconstructions from data gathered from cone-beam
x-ray CT scanning
geometries. The
package is implemented in Matlab with the intention
of being portable across
many computer architectures
and easy to use.
GUI of the Reconstruction
Stage
Download
OSCaR
Right now OSCaR
is in the beta-testing stage. You can download "OSCaR-02" here (Updated December 2008).
Motivation
and Purpose
The Feldkamp-Davis-Kress (FDK)
reconstruction framework for 3D cone-beam CT reconstruction has been known since 1984. However, the lack of availability of
practical, flexible, free FDK software implementations often hampers
medical physics researchers and inhibits multi-institutional research
collaboration. Recognizing the need for common, reference-able
imaging
research software, the American Association for
Physicists in Medicine
(AAPM) Imaging Research Subcommittee has
supported the development of "OSCaR", an open-source Matlab
implementation of CBCT reconstruction for free distribution as a
research tool by the AAPM. The goal is to offer a straightforward, open
source code and GUI implementation that emphasizes flexibility,
generality, and ease of use. The implementation has a
transparent
interface for 3D image reconstruction with the intention of providing a
useful base platform for developing advanced techniques (e.g., artifact
correction) or for conducting image quality studies (e.g., selection of
optimal reconstruction filters). Some simple test image data is also
included. The code is intended for research use,
rather than clinical
or commercial implementation.
Methods
and Materials
Broadly speaking, OSCaR consists of
three main stages: pre-processing, reconstruction, and export. In the pre-processing stage, CBCT data is parsed
from a broad, general base of
standard data-file formats (e.g., DICOM, binary, JPEG, TIFF, PNG,
etc.). Geometric corrections, pixel aperture, sampling, air
normalization, and other device-dependent parameters associated
with
the projection data are applied. In the reconstruction stage, OSCaR permits the specification of a
Field-Of-View (FOV), voxel size, and
reconstruction filters. The actual voxel-driven reconstruction uses the
well-known FDK filtered back-projection algorithm. In the export stage
the reconstructed data and the maximum/minimum of the
reconstructed
volume can be saved in a *.mat file. Although compiled software is certainly
faster than interpreted Matlab
code, a Matlab implementation circumvents the use of custom compilation
libraries. The result is a software tool that is easy to use and can be
rapidly adapted and modified for new research purposes.
In accordance
with the desires of the AAPM Imaging Research Subcommittee, OSCaR
will be made freely available on the AAPM web-site to members of the
AAPM for research in algorithm development, CBCT image
quality, and
multi-institutional collaboration.
- This work was supported by the
AAPM Imaging Research Subcommittee, MITACS and Princess Margaret
Hospital.