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Title: Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner

Abstract

The aim of our work is to describe the way in which physical figures of merit such as contrast-to-noise ratio (CNR) behave when varying acquisition parameters such as emission scan duration (ESD) or activity at the start of acquisition (A{sub acq}) that in clinical practice can be selected by the user, or object properties such as target dimensions or target-to-background (T/B) ratio, which depend uniquely on the intrinsic characteristics of the object being imaged. Figures of merit, used to characterize image quality and quantitative accuracy for a 3D-LSO based PET/CT scanner, were studied as a function of ESD and A{sub acq} for different target sizes and T/B ratios using a multivariate approach in a wide range of conditions approaching the ones that can be encountered in clinical practice. An annular ring of water bags of 3 cm thickness was fitted over an IEC phantom in order to obtain counting rates similar to those found in average patients. The average scatter fraction (SF) of the modified IEC phantom was similar to the mean SF measured on patients with a similar scanner. A supplemental set of micro-hollow spheres was positioned inside the phantom. The NEMA NU 2-2001 scatter phantom was positioned atmore » the end of the IEC phantom to approximate the clinical situation of having activity that extends beyond the scanner. The phantoms were filled with a solution of water and {sup 18}F (12 kBq/mL) and the spheres with various T/B ratios of 22.5, 10.3, and 3.6. Sequential imaging was performed to acquire PET images with varying background activity concentrations of about 12, 9, 6.4, 5.3, and 3.1 kBq/mL, positioned on the linear portion of the phantom's NECR curve, well below peak NECR of 61.2 kcps that is reached at 31.8 kBq/mL. The ESD was set to 1, 2, 3, and 4 min/bed. With T/B ratios of 3.6, 10.3, and 22.5, the 13.0, 8.1, and 6.5 mm spheres were detectable for the whole ranges of background activity concentration and ESD, respectively. The ESD resulted as the most significant predictor of CNR variance, followed by T/B ratio and the cross sectional area of the given sphere. Only last comes A{sub acq} with a weight more than halved with respect to ESD. Thus, raising ESD seems to be much more effective than raising A{sub acq} in order to obtain higher CNR, which is the physical figure of merit closely related with target detectability, at least in the simple task of the signal known exactly background known exactly model.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Department of Medical Physics, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara (Italy)
Publication Date:
OSTI Identifier:
21032802
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 34; Journal Issue: 10; Other Information: DOI: 10.1118/1.2776242; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; COMPUTERIZED TOMOGRAPHY; COUNTING RATES; FLUORINE 18; IMAGE PROCESSING; IMAGES; MULTIVARIATE ANALYSIS; NOISE; PATIENTS; PHANTOMS; POSITRON COMPUTED TOMOGRAPHY; THICKNESS

Citation Formats

Brambilla, M, Matheoud, R, Secco, C, Sacchetti, G, Comi, S, Rudoni, M, Carriero, A, Inglese, E, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Medical Physics, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Radiology, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, and Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara. Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner. United States: N. p., 2007. Web. doi:10.1118/1.2776242.
Brambilla, M, Matheoud, R, Secco, C, Sacchetti, G, Comi, S, Rudoni, M, Carriero, A, Inglese, E, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Medical Physics, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Radiology, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, & Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara. Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner. United States. https://doi.org/10.1118/1.2776242
Brambilla, M, Matheoud, R, Secco, C, Sacchetti, G, Comi, S, Rudoni, M, Carriero, A, Inglese, E, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Medical Physics, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, Department of Radiology, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara, and Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara. Mon . "Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner". United States. https://doi.org/10.1118/1.2776242.
@article{osti_21032802,
title = {Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner},
author = {Brambilla, M and Matheoud, R and Secco, C and Sacchetti, G and Comi, S and Rudoni, M and Carriero, A and Inglese, E and Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara and Department of Medical Physics, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara and Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara and Department of Radiology, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara and Department of Nuclear Medicine, Universita degli Studi del Piemonte Orientale A. Avogadro, Azienda Ospedaliera Maggiore della Carita, Corso Mazzini 18, 28100 Novara},
abstractNote = {The aim of our work is to describe the way in which physical figures of merit such as contrast-to-noise ratio (CNR) behave when varying acquisition parameters such as emission scan duration (ESD) or activity at the start of acquisition (A{sub acq}) that in clinical practice can be selected by the user, or object properties such as target dimensions or target-to-background (T/B) ratio, which depend uniquely on the intrinsic characteristics of the object being imaged. Figures of merit, used to characterize image quality and quantitative accuracy for a 3D-LSO based PET/CT scanner, were studied as a function of ESD and A{sub acq} for different target sizes and T/B ratios using a multivariate approach in a wide range of conditions approaching the ones that can be encountered in clinical practice. An annular ring of water bags of 3 cm thickness was fitted over an IEC phantom in order to obtain counting rates similar to those found in average patients. The average scatter fraction (SF) of the modified IEC phantom was similar to the mean SF measured on patients with a similar scanner. A supplemental set of micro-hollow spheres was positioned inside the phantom. The NEMA NU 2-2001 scatter phantom was positioned at the end of the IEC phantom to approximate the clinical situation of having activity that extends beyond the scanner. The phantoms were filled with a solution of water and {sup 18}F (12 kBq/mL) and the spheres with various T/B ratios of 22.5, 10.3, and 3.6. Sequential imaging was performed to acquire PET images with varying background activity concentrations of about 12, 9, 6.4, 5.3, and 3.1 kBq/mL, positioned on the linear portion of the phantom's NECR curve, well below peak NECR of 61.2 kcps that is reached at 31.8 kBq/mL. The ESD was set to 1, 2, 3, and 4 min/bed. With T/B ratios of 3.6, 10.3, and 22.5, the 13.0, 8.1, and 6.5 mm spheres were detectable for the whole ranges of background activity concentration and ESD, respectively. The ESD resulted as the most significant predictor of CNR variance, followed by T/B ratio and the cross sectional area of the given sphere. Only last comes A{sub acq} with a weight more than halved with respect to ESD. Thus, raising ESD seems to be much more effective than raising A{sub acq} in order to obtain higher CNR, which is the physical figure of merit closely related with target detectability, at least in the simple task of the signal known exactly background known exactly model.},
doi = {10.1118/1.2776242},
url = {https://www.osti.gov/biblio/21032802}, journal = {Medical Physics},
issn = {0094-2405},
number = 10,
volume = 34,
place = {United States},
year = {2007},
month = {10}
}