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M Unterweger

Publications and source records attributed to M Unterweger.

At least 19 recordsLinked to original sources
PubMed2006

Calibration of HPGe gamma-ray detectors for measurement of radioactive noble gas sources.

Measurements of radioactive noble gases are routinely made with gamma-ray spectrometers. This work describes the calibration of high purity germanium detectors provided by the full-energy-peak efficiency as a function of the gamma-ray energy. A comparison of measured efficiency values with a new, simplified method based on a direct mathematical method is given here.

Journal Article↗
PubMed2006

Development of gamma-ray emitting test sources for portal monitors.

A new set of gamma-ray emitting test sources was designed by the National Institute of Standards and Technology (NIST) for testing of radiation portal monitors for homeland security applications. This paper provides a description of the construction and characterization of these new sources that were designed and built to meet the American National Standard Institute (ANSI) N42.35-2004 and N42.38 standards' requirements.

Equipment Failure Analysis↗
PubMed2005

[CME radiology 8].

Explore the source record for details and available documents.

Aged, 80 and over↗
PubMed2005

Dose optimization of contrast-enhanced carotid MR angiography.

The purpose of this work was to compare the diagnostic performance of a single-contrast or a double-contrast dose of carotid contrast-enhanced MR angiography (MRA). One-hundred nineteen patients (mean age 65+/-14.4 years) underwent carotid contrast-enhanced MRA with a standardized protocol (repetition time/echo 3.73 ms/1.38 ms, flip-angle 25 degrees, acquisition-time 19 s, voxel size 1.2 x 1.2 x 0.9 mm3) on a 1.5-T scanner (Sonata, Siemens-Medical-Systems) using a neck phased-array coil. Contrast agent was administered intravenously at a rate of 3.0 ml/s, either as a single dose (n=57; 0.1 mmol/kg body weight) or as a double dose (n=62; 0.2 mmol/kg body weight) of meglumine gadoterate (0.5 M/l), followed by 30 ml saline. Qualitative image analysis was performed on maximum intensity projections using a five-point scale. Signal intensities were measured at three different vascular levels on both sides to assess the contrast-to-noise ratios (CNRs). Image quality was rated as good or excellent in all cases. A double dose did not influence the efficacy of carotid enhancement (CNR single dose 69.12+/-19.8; CNR double dose 70.01+/-20.7; p = 0.81) compared with a single dose. In both dose groups the mean CNRs were inversely related to bodyweight, despite adjusted contrast volumes (p=0.0005). Double-dose contrast-enhanced carotid MRA is not superior to single-dose MRA, as overall diagnostic performance and quantitative contrast enhancement are equal. Being more cost-efficient, a single-dose administration of contrast agent is recommended for MRA of the carotid arteries.

Adult↗