نتایج جستجو برای: attenuation correction

تعداد نتایج: 212408  

Journal: :Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 2009
Gavin L Noble Alan W Ahlberg Aravind Rao Kokkirala S James Cullom Timothy M Bateman Giselle M Cyr Deborah M Katten Glenn D Tadeo James A Case David M O'Sullivan Gary V Heller

BACKGROUND Although attenuation correction (AC) has been successfully applied to large field of view (LFOV) cameras, applicability to small field of view (SFOV) cameras is a concern due to truncation. This study compared perfusion images between a LFOV and SFOV camera with truncation compensation, using the same AC solution. METHODS AND RESULTS Seventy-eight clinically referred patients under...

Journal: :Remote Sensing 2023

X-band dual-polarization phased-array weather radars (X-PARs) have been used in South China extensively. Eliminating the attenuation and system bias of radar data is key to utilizing advantage X-PAR networks. In this paper, disdrometer raindrop-size distribution (DSD) measurements are calculate polarimetric variables analyze characteristics precipitation attenuation. Furthermore, based on netwo...

Journal: :Annals of nuclear medicine 2009
Koichi Okuda Kenichi Nakajima Nobutoku Motomura Masahiro Kubota Noriyasu Yamaki Hisato Maeda Shinro Matsuo Seigo Kinuya

OBJECTIVE Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) method can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusio...

Arman Rahmim Maryam Shirmohammad Mohammad Reza Ay, Saeed Sarkar

Introduction:  The  advent  of  dual-modality  PET/CT  scanners  has  revolutionized  clinical  oncology  by  improving lesion localization and facilitating treatment planning for radiotherapy. In addition, the use of  CT images for CT-based attenuation correction (CTAC) decreases the overall scanning time and creates  a noise-free  attenuation  map  (6map).  CTAC  methods  include  scaling,  s...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2004
Thomas Beyer Gerald Antoch Stefan Müller Thomas Egelhof Lutz S Freudenberg Jörg Debatin Andreas Bockisch

UNLABELLED Since its introduction in 1998, dual-modality PET/CT imaging has received great attention in the medical community. For the first time, patients can be examined with both CT and PET in a single examination. A whole-body survey is the standard mode of acquisition. The CT images are used for anatomic reference of the tracer uptake patterns imaged in PET, as well as for attenuation corr...

2016
K. Gerrit Held Michael Jaeger Jaro Rička Martin Frenz H. Günhan Akarçay

Spectral optoacoustic (OA) imaging enables spatially-resolved measurement of blood oxygenation levels, based on the distinct optical absorption spectra of oxygenated and de-oxygenated blood. Wavelength-dependent optical attenuation in the bulk tissue, however, distorts the acquired OA spectrum and thus makes quantitative oxygenation measurements challenging. We demonstrate a correction for this...

2011
Ákos Szlávecz Gábor Hesz Tamás Bükki Balázs Benyó

Parallel projection based Single Photon Emission Computed Tomography (SPECT) is one of the most widely used nuclear imaging technique even nowadays. Serious artefacts are produced in the reconstructed images due to the non-homogeneous attenuation medium and the distance dependent spatial resolution (DDSR) of the parallel imaging. Effective non-uniform attenuation correction and DDSR reduction p...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2003
Elena Dizendorf Thomas F Hany Alfred Buck Gustav K von Schulthess Cyrill Burger

UNLABELLED CT images represent essentially noiseless maps of photon attenuation at a range of 40-140 keV. Current dual-modality PET/CT scanners transform them into attenuation coefficients at 511 keV and use these for PET attenuation correction. The proportional scaling algorithms hereby used account for the different properties of soft tissue and bone but are not prepared to handle material wi...

Journal: :Medical physics 2010
Gaspar Delso Axel Martinez-Möller Ralph A Bundschuh Stephan G Nekolla Sibylle I Ziegler

PURPOSE A critical question in the development of combined MR/PET scanners is whether MR can provide the tissue attenuation data required for PET reconstruction. Unfortunately, MR images are often unable to encompass the entire patient. The resulting truncation in the transverse plane leads to incomplete attenuation maps, causing artifacts in the reconstructed PET image. This article describes ...

2014
Alan J. Riordan Edwin Bennink Jan Willem Dankbaar Max A. Viergever Birgitta K. Velthuis Ewoud J. Smit Hugo W. A. M. de Jong

PURPOSE In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for parti...

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