Objective In this study open-source software (QSPECT) suitable for the
iterative reconstruction of single-photon emission computed tomography
(SPECT) data is presented. QSPECT implements maximum likelihood
expectation maximization and ordered subsets expectation maximization
algorithms in a user-friendly graphical interface. The software
functionality is described and validation results are presented.
Methods Maximum likelihood expectation maximization and ordered subsets
expectation maximization algorithms are implemented in C++. The Qt
toolkit, a standard C++ framework for developing high-performance
cross-platform applications, has been used for the graphical user
interface development. QSPECT is tested using original projection data
from two clinical SPECT systems: (i) APEX SPX-6/6HR and (ii) Millennium
MG. Phantom experiments were carried out to evaluate the quality of
reconstructed images in terms of (i) spatial resolution, (ii)
sensitivity to activity variations, and (iii) the presence of scatter
media. A cardiac phantom was used to simulate a normal and abnormal
scenario. Finally, clinical cardiac SPECT images were reconstructed. In
all cases, QSPECT results were compared with the clinical systems
reconstruction software that uses the standard filtered backprojection
algorithm.
Results The reconstructed images show that QSPECT, when compared with
standard clinical reconstruction, provides images with higher contrast,
reduced background, and better separation of small sources located in
small distances. In addition, reconstruction with QSPECT provides more
quantitative images, and reduces the background created by scatter
media. Finally, the phantom and clinical cardiac images are
reconstructed with similar quality.
Conclusion QSPECT is a freely distributed, open-source standalone
application that provides real-time, high-quality SPECT images. The
software can be further modified to improve reconstruction algorithms,
and include more correction techniques, such as, scatter and attenuation
correction. Nucl Med Commun 31: 558-566 (C) 2010 Wolters Kluwer Health |
Lippincott Williams & Wilkins
