Search results for "Sound"
showing 10 items of 1845 documents
Trap Spectroscopy by the Glow Rate Technique using Bleaching of Colour Centres
2002
An application of the glow rate technique (GRT) for analysis of the parameters of thermostimulated decay of colour centres is presented using the data on the decay of radiation defects in LiBaF 3 :Fe crystals created by X rays at 300 K. The GRT offers a procedure for evaluation of the mean activation energy as a function of temperature in the case of arbitrary thermostimulated relaxation kinetics represented by the trap distribution function. The experimental procedure involves at least two subsequent measurements of thermostimulated decay kinetics at different heating rates. It is shown that the decay of the F type centres is governed by interaction of mobile anion vacancies with F A and F…
Visual abstract for Abdominal Radiology: what it is, why we need it and how to make it
2021
Visual abstract for Abdominal Radiology: what it is, why we need it and how to make it
La diagnostica delle malattie infettive: Tra metafora del passato e itinerario nel futuro
1993
A global emergency is threatening mankind, awakening dead ghosts and causing alarm about our present and future: it is the apparently irreversible spread of infectious diseases.This critical and worrying situation should be acknowledged and carefully followed by the radiological profession since all of us – teachers, specialists, professionals – have to deal with imaging diagnostic modalities deriving information from a deceitful and camouflageing anatomo-functional substratum.The increasing spread of infectious diseases is due to a wide range of concomitant factors: HIV infection, drug addiction, migration fenomena and the related opportunistic infections combined with poor hygienic, physi…
MR imaging of the lungs with hyperpolarized helium-3 gas transported by air.
2002
Hyperpolarized noble gas MRI shows promise in the functional imaging of the pulmonary air spaces. The production of hyperpolarized (HP) gas requires specialized laser optical pumping apparatus, which is not likely to be home built in the majority of clinical MRI radiology centres. There are two routes through which HP gas will be made available to hospitals for clinical use: either the apparatus will be installed locally at a considerable expense to the centre, or a central facility will produce the gas and then deliver it to remote MRI sites as and when required. In this study, the feasibility of transporting large quantities of HP gas for in vivo MR imaging from a remote production facili…
Thermolumineszenzdosimetrie zur Ermittlung der Teilkörperdosen der Hände bei unfallchirurgischen Operationen
1997
Zusammenfassung In der Rontgenverordnung 1987 werden vom Gesetzgeber Grenzwerte fur die Teilkorperdosen der Hande beruflich strahlenexponierter Personen genannt. Um zu uberprufen, ob diese bei speziellen Operationsarten erreicht werden konnen, wurde mittels Fingerringdosimeter die Strahlenbelastung der Hande des Operateurs und des 1. Assistenten bei 34 Marknagelungen ermittelt. Die Erfassung der Strahlenbelastung erfolgte mittels Thermolumineszenzdosimetrie. Die ermittelten Werte zeigen, daβ es theoretisch nur dann zu einer Uberschreitung der vom Gesetzgeber vorgeschriebenen Grenzwerte (von 500 mSv fur die Hande bei beruflich strahlenexponierten Personen der Gruppe A) kommen konnte, wenn me…
Evaluation of washout using subtraction MRI for the diagnosis of hepatocellular carcinoma in cirrhotic patients with spontaneously T1-hyperintense no…
2023
Purpose: The purpose of this study was to assess the value of subtraction imaging on post-arterial phase images (i.e., portal venous, delayed/transitional and hepatobiliary phases) for the non-invasive diagnosis of hepatocellular carcinoma (HCC) in spontaneously hyperintense nodules on T1-weighted imaging in patients with cirrhosis. Materials and methods: Forty-five patients with a total 55 hepatic nodules that were spontaneously hyperintense on T1-weighted images were initially retrieved. All patients underwent MRI examination of the liver using extracellular agent. Each nodule was assessed for sensitivity and specificity using LI-RADS (Liver Imaging Reporting and Data System) during two r…
Joint image and motion reconstruction for PET using a B-spline motion model.
2012
We present a novel joint image and motion reconstruction method for PET. The method is based on gated data and reconstructs an image together with a motion function. The motion function can be used to transform the reconstructed image to any of the input gates. All available events (from all gates) are used in the reconstruction. The presented method uses a B-spline motion model, together with a novel motion regularization procedure that does not need a regularization parameter (which is usually extremely difficult to adjust). Several image and motion grid levels are used in order to reduce the reconstruction time. In a simulation study, the presented method is compared to a recently propos…
Neuroimaging of Visual Pathway Pathology
2004
Monte Carlo dosimetric study of the BEBIG Co-60 HDR source
2005
Although not as widespread as Ir-192, Co-60 is also available on afterloading equipment devoted to high dose rate brachytherapy, mainly addressed to the treatment of gynaecological lesions. The purpose of this study is to obtain the dosimetric parameters of the Co-60 source used by the BEBIG MultiSource remote afterloader (BEBIG GmbH, Germany) for which there are no dosimetric data available in the literature. The Monte Carlo code GEANT4 has been used to obtain the TG43 parameters and the 2D dose rate table in Cartesian coordinates of the BEBIG Co-60 HDR source. The dose rate constant, radial dose function and anisotropy function have been calculated and are presented in a tabular form as w…