title: [Practical electron dosimetry. A comparison of different types of ionization chambers].
abstract: Since Markus chambers are no longer recommended in the 1997 DIN 6800-2 version there are uncertainties as to the use of alternative chamber types for electron dosimetry. Therefore, we performed a comparison between different types of ionization chambers. In particular, the widespread Farmer and Roos chambers were compared with the Markus chamber for polarity effect, chamber-to-chamber variation, and deviations of the measured absorbed dose relative to the value obtained with the Roos chamber (which is regarded as an ideal Bragg-Gray-chamber). The perturbation correction factor at 60Co radiation was determined experimentally as 1,029 +/- 0.5% (Roos chamber) and 1,018 +/- 0.5% (Markus chamber) for the investigated plane-parallel chambers. In addition, we could show that the Roos chambers do not have a larger chamber-to-chamber variation than the Farmer chambers. Likewise, our results suggest that Farmer chambers could be used for electron energies above 6 MeV.
authors: Abteilung für Medizinische Physik, Klinik für Radioonkologie, Universitätsklinik Tübingen.
authors: Oliver S
authors: OS
authors: Dohm
authors: Gunter
authors: G
authors: Christ
authors: Edmund
authors: E
authors: Schüle
mesh_terms: D004583:Electrons; D011522:Protons; D011874:Radiometry / Q000295:instrumentation / Q000379:methods
chemical_list: D011522:Protons