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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 4 (2000), S. 213-216 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Panoramaschichtaufnahme ; Digitale Radiographie ; Dosismessungen ; Strahlenexposition ; Effektive Dosis ; Keywords Panoramic radiography ; Digital ¶radiography ; Dosimetry ; Radiation exposure ; Effective dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Objective: The purpose of our study was to measure and compare patient exposure by direct digital and conventional panoramic radiography. Material and methods: Dose measurements were carried out on an anthropomorphic phantom, which was specially developed for dental radiography. Panoramic radiographs were taken with three different conventional devices (Orthopantomograph 10E, Orth Oralix FD, Siemens Orthophos) and two direct digital devices (Orthopantomograph 100 Digipan, Siemens Orthophos DS Ceph). The exposure conditions were according to clinical routine. The energy dose was measured at 28 places inside and on the surface of the phantom by using a set of 108 thermoluminescence detectors. Additionally, exposure time, tube voltage, central-beam dose, and dose-area products were measured. The effective doses were calculated on the basis of the absorbed doses. Results: In each case, the highest energy doses were recorded at the parotid gland, the mandibular angle, the submandibular gland, and the skin in the neck. Panoramic radiographs taken with the conventional units yielded in effective doses in the range of 16–21 μSv, the digital units caused 5 or 14 μSv. Conclusion: In comparison with conventional techniques, patient exposure can be reduced by direct digital panoramic radiography. The extent of dose reduction depends on the ¶device employed and is generally smaller than the dose reduction that can be achieved by digital imaging devices in intraoral radiography.
    Notes: Fragestellung: Durch systematische Dosismessungen sollte geklärt werden, ob durch digitale Panoramaschichtaufnahmen gegenüber der konventionellen Technik eine Verringerung der Strahlenexposition des Patienten erreicht werden kann. Material und Methode: Die Dosismessungen erfolgten an einem anthropomorphen Phantom, das speziell für Untersuchungen zur zahnärztlichen Röntgendiagnostik entwickelt worden war. Mit Expositionsbedingungen, die der klinischen Routine entsprachen, wurden Panoramaschichtaufnahmen des Phantoms mit 3 unterschiedlichen konventionellen Geräten (Orthopantomograph 10E, Orth Oralix FD, Siemens Orthophos) und 2 digitalen Geräten (Orthopantomograph 100 Digipan, Siemens Orthophos DS Ceph) erstellt. Dabei wurde die Energiedosis an 28 Messorten am Phantom sowie im Zentralstrahl unter Verwendung von 108 Thermolumineszenzdetektoren bestimmt. Zudem wurden Schaltzeiten, Röhrenspannung und Dosis-Flächen-Produkte registriert. Auf Grundlage der Dosismessungen erfolgte eine Abschätzung der effektiven Dosen. Ergebnisse: Die jeweils höchsten Energiedosiswerte wurden im Bereich der Glandula parotis, im Kieferwinkel, in der Glandula submandibularis und an der Nackenhaut registriert. Bei Verwendung der konventionellen Geräte ergaben sich effektive Dosen von 16–21 μSv, bei den digitalen Geräten von 5 bzw. 14 μSv. Schlussfolgerungen: In Abhängigkeit vom eingesetzten Gerät kann durch digitale Panoramaschichtaufnahmen eine Verminderung der Strahlenexposition des Patienten erreicht werden. Das Ausmaß der Dosisreduktion ist jedoch geringer als beim entsprechenden Vergleich von konventionellen und digitalen Systemen für intraorale Aufnahmen.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 26 (1988), S. 274-280 
    ISSN: 1612-1112
    Keywords: Capillary gas chroamtography ; 2,4-dinitrophenylhydrazones ; Aldehydes and carbonyl compounds ; Automobile exhaust gas ; Liquefied petroleum gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The exhaust gas of a LPG fuelled engine is drawn through two bubblers in series in an ice bath, and filled with saturated 2,4-dinitrophenylhydrazine in 2M HCl. After heating the derivatives are extracted with toluene-cyclohexane and 1μl samples injected “on-column” on a OV1 capillary column. Using an FID the lower limit of detection is 15–18 pg for formaldehyde (about 8–10 ppbv for a 16l exhaust sample). Taking the blank into account, the limit is about 40 ppbv. The exhaust gases of a LPG-fuelled engine contain formaldehyde, acetaldehyde, propionaldehyde, acrolein and acetone. Carbonyl compounds of more than 3 C-atoms were not found in detectable amounts. The engine was rund under stoichiometric, lean and rich air/fuel conditions. Under rich conditions the concentrations of the aldehydes were: formaldehyde 2.8 ppm, acetaldehyde 1.3 ppm, propionaldehyde 0.06 ppm, acrolein 0.03 ppm, acetone 0.17 ppm; under stoichiometric conditions: 4.5, 1.6, 0.10, 0.03 and 0.18 ppm respectively; under lean conditions 17.0, 2.9, 0.13, 0.07 and 0.27 ppm respectively. These figures demonstrate the necessity of measuring aldehydes in exhaust gases of LPG-fuelled engines.
    Type of Medium: Electronic Resource
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