Dual energy versus single energy MDCT: measurement of radiation dose using adult abdominal imaging protocols

RATIONALE AND OBJECTIVES: The aim of this study was to measure the radiation dose of dual-energy and single-energy multidetector computed tomographic (CT) imaging using adult liver, renal, and aortic imaging protocols. MATERIALS AND METHODS: Dual-energy CT (DECT) imaging was performed on a conventional 64-detector CT scanner using a software upgrade (Volume Dual Energy) at tube voltages of 140 and 80 kVp (with tube currents of 385 and 675 mA, respectively), with a 0.8-second gantry revolution time in axial mode. Parameters for single-energy CT (SECT) imaging were a tube voltage of 140 kVp, a tube current of 385 mA, a 0.5-second gantry revolution time, helical mode, and pitch of 1.375:1. The volume CT dose index (CTDI(vol)) value displayed on the console for each scan was recorded. Organ doses were measured using metal oxide semiconductor field-effect transistor technology. Effective dose was calculated as the sum of 20 organ doses multiplied by a weighting factor found in International Commission on Radiological Protection Publication 60. Radiation dose saving with virtual noncontrast imaging reconstruction was also determined. RESULTS: The CTDI(vol) values were 49.4 mGy for DECT imaging and 16.2 mGy for SECT imaging. Effective dose ranged from 22.5 to 36.4 mSv for DECT imaging and from 9.4 to 13.8 mSv for SECT imaging. Virtual noncontrast imaging reconstruction reduced the total effective dose of multiphase DECT imaging by 19% to 28%. CONCLUSION: Using the current Volume Dual Energy software, radiation doses with DECT imaging were higher than those with SECT imaging. Substantial radiation dose savings are possible with DECT imaging if virtual noncontrast imaging reconstruction replaces precontrast imaging.

Eine Karriere im Schatten von Rosalba Carriera. Felicita Sartori / Hoffmann in Venedig und Dresden

Felicita Sartori, nata a Pordenone nel 1714 ca. come figlia del notaio Felice Sartori e di Tommasa Scotti, ricevette la sua prima formazione artistica intorno al 1724 da suo zio, il calcografo Antonio dall'Agata a Gorizia. Tramite lo zio la quattordicenne si trasferisce a Venezia dove entra nella bottega-casa di Rosalba Carriera per perfezionarsi nella miniatura e nella pittura a pastello senoché nelle varie tecniche della grafica. Durante gli anni seguenti Felicita diventa, accanto alle sorelle di Rosalba, la collaboratrice piú stretta della Carriera che in questi anni tocca il colmo della fama artistica, dovuto soprattutto al suo strepitoso successo riscosso durante il soggiorno a Parigi dal 1720 al 1721. I numerosissimi incarichi che le giungono da tutta l'Europa incrementano la produttivitá e lasciano supporre che la bottega abbia contribuito in misura notevole a contentare tali richieste. Negli anni dopo il 1730 l'attività di Felicita oltre le varie attività pittoriche entro la bottega della Carriera si estende alla produzione di incisioni per le pubblicazioni di Gaspare Stampa e di Jacques-Bénigne Bossuet. Incide inoltre le stampe dai disegni di Giovanni Battista Piazetta, pubblicati da Antonio Maria Zanetti. La finora anonima collaboratrice della famosa veneziana esce dall'ombra quando, nel 1741, viene nominata artista di corte da Augusto III, principe elettore di Sassonia e ré di Polonia. Trasferitosi a Dresda, si unisce poche settimane dopo la nomina in matrimonio al consigliere di corte Franz Joseph von Hoffmann, che probabilmente aveva concosciuto nel 1740 nello studio veneziano di Rosalba spesso frequentato dall'elettore e del suo seguito. Felicita continua la su attività a Dresda dove nella Gemäldegalerie Alte Meister si conservano tuttora 15 miniature di sua mano. Grazie alle ricerche dedicate a queste opere è stato possibile di aumentare l'œuvre della Sartori di altre opere tra cui una Betsabea al bagno (coll. priv. München) già nelle collezioni reali sassoni. Sembra che l'artista dopo la morte del marito nel 1749, si sia trasferito con un secondo marito a Bamberg ma altre fonti citano la sua presenza a Dresda nel 1753 dove secondo le notizie fornite da Jean Pierre Mariette muore nel 1760 all'età di soli 46 anni.

An efficient simulation algorithm for the generalized von Mises distribution of order two

In this article we propose an exact efficient simulation algorithm for the generalized von Mises circular distribution of order two. It is an acceptance-rejection algorithm with a piecewise linear envelope based on the local extrema and the inflexion points of the generalized von Mises density of order two. We show that these points can be obtained from the roots of polynomials and degrees four and eight, which can be easily obtained by the methods of Ferrari and Weierstrass. A comparative study with the von Neumann acceptance-rejection, with the ratio-of-uniforms and with a Markov chain Monte Carlo algorithms shows that this new method is generally the most efficient.

Precise Orbit Determination of Low Earth Satellites at AIUB using GPS and SLR data

An ever increasing number of low Earth orbiting (LEO) satellites is, or will be, equipped with retro-reflectors for Satellite Laser Ranging (SLR) and on-board receivers to collect observations from Global Navigation Satellite Systems (GNSS) such as the Global Positioning Sys- tem (GPS) and the Russian GLONASS and the European Galileo systems in the future. At the Astronomical Insti- tute of the University of Bern (AIUB) LEO precise or- bit determination (POD) using either GPS or SLR data is performed for a wide range of applications for satellites at different altitudes. For this purpose the classical numeri- cal integration techniques, as also used for dynamic orbit determination of satellites at high altitudes, are extended by pseudo-stochastic orbit modeling techniques to effi- ciently cope with potential force model deficiencies for satellites at low altitudes. Accuracies of better than 2 cm may be achieved by pseudo-stochastic orbit modeling for satellites at very low altitudes such as for the GPS-based POD of the Gravity field and steady-state Ocean Circula- tion Explorer (GOCE).

Ankündigung eines Unterrichts in der mosaischen Religion und in den dieselbe betreffenden Kenntnissen : in zweckmäßigen Vorträgen u. Unterhaltungen für Israeliten

[Verf.: Philipp Lazarus Hurwitz]

An introductory lecture delivered in the University of London

by Hyman Hurwitz

Sagen der Hebräer : aus d. Schriften d. alten hebräischen Weisen

aus d. Engl. des Heimann Hurwitz von [Gottfried Wilhelm Becke]r

Sagen der Hebräer : aus d. Schriften d. alten hebräischen Weisen

aus d. Engl. des Heimann Hurwitz von [Gottfried Wilhelm Becke]r

A grammar of the Hebrew language

by Hyman Hurwitz

Anfangsgrinde dr ariṭmeṭik tzum gbroich dr jugnd der jidišn naṭtziohn inzondrheiṭ ...

frfassṭ und heroisgegebn fon Feibš Segel Hurwitz