| Zugriffsnummer | 14773 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | Development of a multi-electrode extrapolation chamber as a prototype of a primary standard for the realization of the unit of the absorbed dose to water for beta brachytherapy sources |
| Autor(in); Institution |
Bambynek, Markus; 6.204, Darstellung und Weitergabe der Einheit der Wasser-Energiedosis für Röntgenstrahlen- und Brachytherapie, PTB-Braunschweig
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| Quelle/Jahr | Nuclear Instruments and Methods in Physics Research A: 492 (2002), 264 - 275 |
| ISSN | 0168-9002 |
| Verlag | Amsterdam: North-Holland, Elsevier |
| Freie Schlagworte | Extrapolation chamber ; Primary standard ; Beta dosimetry ; Intravascular brachytherapy |
| Zusammenfassung | The prototype of a primary standard has been developed, built and tested, which enables the realization of the unit of the absorbed dose to water for beta brachytherapy sources. In the course of the development of the prototype, the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 60 (TG60) and the Deutsche Gesellschaft für Medizinische Physik (DGMP) Arbeitskreis 18 (AK18) were taken into account. The prototype is based on a new multi-electrode extrapolation chamber (MEC) which meets in particular the requirements on high spatial resolution and small uncertainty. The central part of the MEC is a segmented collecting electrode which was manufactured in the clean room center of PTB by means of electron beam lithography on a wafer. A precise displacement device consisting of three piezoelectric macrotranslators has been incorporated to move the wafer collecting electrode against the entrance window. For adjustment of the wafer collecting electrode parallel to the entrance foil, an electro-mechanical adjustment system based on a capacitance bridge circuit has been developed. The MEC allows a three dimensional dose distribution to be measured with high spatial resolution, without having to fall back on an additional relative dosimetry system. All components of the MEC were separately investigated for suitability. The extrapolation chamber measurements on a plane beta source proved the suitability of the MEC as a primary standard. With seizes of collector electrodes as small as 1 mm × 1 mm, calibrations were performed with a relative combined standard uncertainty of 3.8 %. The reproducibility of the MEC amounted to 1.5 %, with k = 1. |
Zitierung
Bambynek, M. (2002). Development of a multi-electrode extrapolation chamber as a prototype of a primary standard for the realization of the unit of the absorbed dose to water for beta brachytherapy sources. Nuclear Instruments and Methods in Physics Research A, 492, 264–275.