A method for point spread function estimation for accurate quantitative imaging
Aim: A method to determine the point spread function (PSF) of an imaging system based on a set of 3-D Gaussian functions is presented for a robust estimation of the recovery corrections for accurate activity quantification in positron emission tomography (PET) and single-photon emission computed tom...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
March 2018
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| In: |
IEEE transactions on nuclear science
Year: 2018, Volume: 65, Issue: 3, Pages: 961-969 |
| ISSN: | 1558-1578 |
| Online Access: |
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| Author Notes: | A.A. Attarwala, D. Hardiansyah, C. Romanó, M. Roscher, F. Molina-Duran, B. Wängler, and G. Glatting |
| Summary: | Aim: A method to determine the point spread function (PSF) of an imaging system based on a set of 3-D Gaussian functions is presented for a robust estimation of the recovery corrections for accurate activity quantification in positron emission tomography (PET) and single-photon emission computed tomography systems. Materials and Methods: The spatial resolution of the ALBIRA II PET subsystem was determined using a 370-kBq 22Na point source. The measured data were reconstructed with a maximum-likelihood expectation-maximization algorithm. The PSF was calculated based on the National Electrical Manufacturing Association (NEMA) NU4 2008 protocol and on alternative methods based on three 3-D fitting functions for the xyz-directions: 1) a 3-D Gaussian function (3-D 1-Gauss) and convolutions of this function with a pixel size (3-D Gaussp) or source dimension of Ø 0.25 mm (3-D Gausss); 2) the sum of two Gaussian functions (3-D 2-Gauss); and 3) three Gaussian functions (3-D 3-Gauss). Goodness of fit and the method based on an Akaike information criterion were used for choosing the best function. A MATLAB-based mathematical source simulation study was performed to quantify the relevance of PSFs calculated from the different methods. Results: Based on the PSFs calculated from the NEMA protocol, the full-width at half-maximum (FWHM) in xyz-directions were 1.68, 1.51, and 1.50 mm. The corresponding results using 3-D Gauss and 3-D Gausss functions both were (1.87 ± 0.01), (1.70 ± 0.01), and (1.50 ± 0.01) mm and for 3-D Gauss,, were (1.84 ± 0.01), (1.67 ± 0.01), and (1.47 ± 0.01) mm. The FWHMs calculated with 3-D 2-Gauss and 3-D 3-Gauss were (1.78 ± 0.01), (1.74 ± 0.01), and (1.83 ± 0.01) mm and (1.76 ± 0.03), (1.72 ± 0.03), and (1.78 ± 0.03) mm, respectively. All coefficients of variations of the fit parameters were ≤29% and the adjusted R2 were ≥0.99. Based on Akaike weights wi, the 3-D 3-Gauss method was best supported by the data (wi = 100%). The simulation study showed a relative error in quantification of spherical lesions in the range of 15%-45% for lesions of diameters 1-5 mm compared to the PSFs based on the NEMA method. Conclusion: An alternative method to calculate the PSFs of imaging systems to accurately correct for recovery effects is presented. The proposed method includes choosing and fitting of 3-D functions, validation of fitting quality, and choosing the function best supported by the data along with an estimation of the uncertainty. |
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| Item Description: | Gesehen am 04.06.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1558-1578 |