Activity painting: PET images of freely defined activity distributions applying a novel phantom technique

The aim of this work was to develop a novel phantom that supports the construction of highly reproducible phantoms with arbitrary activity distributions for PET imaging. It could offer a methodology for answering questions related to texture measurements in PET imaging. The basic idea is to move a p...

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Bibliographic Details
Published in:PloS one 2019-01, Vol.14 (1), p.e0207658-e0207658
Main Authors: Forgacs, Attila, Kallos-Balogh, Piroska, Nagy, Ferenc, Krizsan, Aron K, Garai, Ildiko, Tron, Lajos, Dahlbom, Magnus, Balkay, Laszlo
Format: Article
Language:English
Subjects:
Arm
Biology and Life Sciences
Calibration
Coefficient of variation
Computer and Information Sciences
Computer simulation
Data acquisition
Evaluation
Field of view
Geometry
Heterogeneity
Humans
Image reconstruction
Imaging, Three-Dimensional
Medical imaging
Medicine and Health Sciences
Methods
Microphones
Monte Carlo simulation
Nuclear medicine
Phantoms, Imaging
Physical Sciences
Positron emission
Positron emission tomography
Quantitative analysis
Reproducibility
Reproducibility of Results
Research and Analysis Methods
Robot arms
Scanners
Signal processing
Simulation
Sodium 22
Spherical shells
Studies
Texture
Three dimensional motion
Tomography
Tomography, X-Ray Computed
Zeolites
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Summary:The aim of this work was to develop a novel phantom that supports the construction of highly reproducible phantoms with arbitrary activity distributions for PET imaging. It could offer a methodology for answering questions related to texture measurements in PET imaging. The basic idea is to move a point source on a 3-D trajectory in the field of view, while continuously acquiring data. The reconstruction results in a 3-D activity concentration map according to the pathway of the point source. A 22Na calibration point source was attached to a high precision robotic arm system, where the 3-D movement was software controlled. 3-D activity distributions of a homogeneous cube, a sphere, a spherical shell and a heart shape were simulated. These distributions were used to measure uniformity and to characterize reproducibility. Two potential applications using the lesion simulation method are presented: evaluation in changes of textural properties related to the position in the PET field of view; scanner comparison based on visual and quantitative evaluation of texture features. A lesion with volume of 50x50x50 mm3 can be simulated during approximately 1 hour. The reproducibility of the movement was found to be >99%. The coefficients of variation of the voxels within a simulated homogeneous cube was 2.34%. Based on 5 consecutive and independent measurements of a 36 mm diameter hot sphere, the coefficient of variation of the mean activity concentration was 0.68%. We obtained up to 18% differences within the values of investigated textural indexes, when measuring a lesion in different radial positions of the PET field of view. In comparison of two different human PET scanners the percentage differences between heterogeneity parameters were in the range of 5-55%. After harmonizing the voxel sizes this range reduced to 2-16%. The general activity distributions provided by the two different vendor show high similarity visually. For the demonstration of the flexibility of this method, the same pattern was also simulated on a small animal PET scanner giving similar results, both quantitatively and visually. 3-D motion of a point source in the PET field of view is capable to create an irregular shaped activity distribution with high reproducibility.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0207658