Martin Spahn

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RATIONALE AND OBJECTIVES To investigate the image quality of a digital radiography system with an amorphous-silicon, large-area, digital flat-panel detector. METHODS A flat-panel detector based on a matrix of amorphous silicon was integrated into a projection radiography system. The scintillator consisted of a layer of structured cesium iodide. The active(More)
RATIONALE AND OBJECTIVES The purpose of this phantom study was to assess the diagnostic performance of a self-scanning, solid-state amorphous silicon (a-Si) detector in skeletal radiography using different exposure parameters. METHODS A flat-panel detector (15 cm x 15 cm), based on a-Si technology with 143 microm x 143 microm pixel size, 1k x 1k matrix,(More)
Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray(More)
After 3 rounds of DNA replication in the presence of BrdU, third-division metaphase cells can be scored for the frequencies of SCEs that occurred during cycles 1 and 2, and also for the frequency of SCE during cycle 3. This procedure was used to resolve the issue of SCE induction by replication of BrdU-substituted DNA templates versus induction by BrdU(More)
Im Gegensatz zur Ureterosigmoideostomie existieren keine verlässlichen klinischen Daten über das Tumorrisiko in den verschiedenen Formen der Harnableitung unter Verwendung isolierter Darmsegmente. In 44 urologischen Hauptabteilungen in Deutschland konnten Operationszahlen, die Operationsindikationen, Patientenalter und Operationsdaten der verschiedenen(More)
RATIONALE AND OBJECTIVES The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography. METHODS Flat-panel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a pixel size of 143 x 143 microns and(More)
The detective quantum efficiency (DQE) is widely accepted as the most relevant parameter to characterize the image quality of medical x-ray systems. In this article we describe a solid method to measure the DQE. The strength of the method lies in the fact that it is self-normalizing so measurements at very low spatial frequencies are not needed.(More)
For all application segments X-ray systems with flat-panel detectors increasingly enter the market. In digital radiography,mammography and cardiologic angiography flat-panel detectors are already well established while they are made ready for market introduction in general angiography and fluoroscopy. Two flat-panel detector technologies are available. One(More)
Die Kalziumoxalat- (CaOx-)Steinbildung ist eine weltweit häufige Erkrankung. Es überrascht daher, dass die pathogenetischen Mechanismen, die zur CaOx-Steinbildung führen, noch weitgehend unbekannt sind. Die lange akzeptierte Hypothese der Steinentstehung durch ein Überschreiten des Löslichkeitsprodukts lithogener Substanzen im Urin ist aber sicherlich nicht(More)