| Zugriffsnummer | 16281 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | Results supporting calculated wall correction factors for cavity chambers |
| Autor(in); Institution |
Büermann, Ludwig; 6.2, Dosimetrie für Strahlentherapie und Diagnostik, PTB-Braunschweig
Kramer, Hans-Michael; 6.2, Dosimetrie für Strahlentherapie und Diagnostik, PTB-Braunschweig
Csete, I.; Orszagos Meresüggyi Hivatal (OMH), Budapest, HUNGARY
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| Quelle/Jahr | Physics in Medicine and Biology: 48 (2003), 21, 3581 - 3594 |
| ISSN | 0031-9155 |
| URL | |
| Verlag | Bristol: IOP Publ. |
| Freie Schlagworte | air kerma standard ; cavity ionization chamber ; wall correction factor ; Monte Carlo methods |
| Zusammenfassung | Thick walled cavity ionization chambers are used by primary standards laboratories as primary air kerma standards in 137Cs and 60Co γ-rays. Application of the cavity theory requires correction for the effects of photon attenuation and scattering in the chamber walls. For more than a decade there have been intensive discussions about the validity of wall correction factors determined by more traditional extrapolation methods versus such calculated by Monte Carlo methods. For existing primary standards the alternative methods lead to results different by up to 50 percent of the correction itself. This report presents both experimental and theoretical results which strongly support the validity of calculated wall correction factors. Moreover, it is demonstrated that, in selected cases, the application of a linear extrapolation method leads to errors in the determination of the air kerma reaching up to 13 percent. |
