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001-es BibID:	BIBFORM075888
035-os BibID:	(cikkazonosító)e0207658 (WOS)000457037500010 (Scopus)85060541521
Első szerző:	Forgács Attila (fizikus)
Cím:	Activity Painting : PET images of freely defined activity distributions applying a novel phantom technique / Forgács A., Kallos-Balogh P., Nagy F., Krizsán Á. K., Garai I., Trón L., Dahlbom M., Balkay L.
Dátum:	2019
ISSN:	1932-6203
Megjegyzések:	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.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Plos One. - 14 : 1 (2019), p. 1-14. -
További szerzők:	Kallos-Balogh Piroska (1996-) Nagy Ferenc (1984-) (fizikus) Krizsán Áron Krisztián (1986-) (fizikus) Garai Ildikó (1966-) (radiológus) Trón Lajos (1941-) (biofizikus) Dahlbom, Magnus Balkay László (1963-) (biofizikus)
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001-es BibID:	BIBFORM125214
035-os BibID:	(scopus)85207360497
Első szerző:	Kallos-Balogh Piroska
Cím:	Multicentric study on the reproducibility and robustness of PET-based radiomics features with a realistic activity painting phantom / Kallos-Balogh Piroska, Vas Norman Felix, Toth Zoltan, Szakall Szabolcs, Szabo Peter, Garai Ildiko, Kepes Zita, Forgacs Attila, Szatmáriné Egeresi Lilla, Magnus Dahlbom, Balkay Laszlo
Dátum:	2024
ISSN:	1932-6203
Megjegyzések:	Previously, we developed an "activity painting" tool for PET image simulation; however, it could simulate heterogeneous patterns only in the air. We aimed to improve this phantom technique to simulate arbitrary lesions in a radioactive background to perform relevant multi-center radiomic analysis. We conducted measurements moving a 22Na point source in a 20-liter background volume filled with 5 kBq/mL activity with an adequately controlled robotic system to prevent the surge of the water. Three different lesion patterns were "activity-painted" in five PET/CT cameras, resulting in 8 different reconstructions. We calculated 46 radiomic indeces (RI) for each lesion and imaging setting, applying absolute and relative discretization. Reproducibility and reliability were determined by the inter-setting coefficient of variation (CV) and the intraclass correlation coefficient (ICC). Hypothesis tests were used to compare RI between lesions. By simulating precisely the same lesions, we confirmed that the reconstructed voxel size and the spatial resolution of different PET cameras were critical for higher order RI. Considering conventional RIs, the SUVpeak and SUVmean proved the most reliable (CV<10%). CVs above 25% are more common for higher order RIs, but we also found that low CVs do not necessarily imply robust parameters but often rather insensitive RIs. Based on the hypothesis test, most RIs could clearly distinguish between the various lesions using absolute resampling. ICC analysis also revealed that most RIs were more reproducible with absolute discretization. The activity painting method in a real radioactive environment proved suitable for precisely detecting the radiomic differences derived from the different camera settings and texture characteristics. We also found that inter-setting CV is not an appropriate metric for analyzing RI parameters' reliability and robustness. Although multicentric cohorts are increasingly common in radiomics analysis, realistic texture phantoms can provide indispensable information on the sensitivity of an RI and how an individual RI parameter measures the texture.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Plos One. - 19 : 10 (2024), p. 1-24. -
További szerzők:	Vas Norman Félix Tóth Zoltán Szakáll Szabolcs Szabó Péter Garai Ildikó (1966-) (radiológus) Képes Zita (1991-) (orvos) Forgács Attila Egeresi Lilla (1992-) (radiográfus) Dahlbom, Magnus Balkay László (1963-) (biofizikus)
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001-es BibID:	BIBFORM075924
Első szerző:	Kallos-Balogh Piroska
Cím:	A novel phantom technique to investigate how different PET scanners measure the same activity shapes and textures / Kallos-Balogh P., Forgács A., Krizsán Á.K., Tóth Z., Szekeres S., Garai I., Dahlbom M., Balkay L.
Dátum:	2018
Tárgyszavak:	Orvostudományok Klinikai orvostudományok előadáskivonat
Megjelenés:	Annual Congress of the European Association of Nuclear Medicine. - p. 262
További szerzők:	Forgács Attila (1985-) (fizikus) Krizsán Áron Krisztián (1986-) (fizikus) Tóth Z. Szekeres Sarolta Garai Ildikó (1966-) (radiológus) Dahlbom, Magnus Balkay László (1963-) (biofizikus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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