Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam.
Fiche publication
Date publication
août 2014
Journal
The Review of scientific instruments
Auteurs
Membres identifiés du Cancéropôle Est :
Pr FROMM Michel, Dr MAVON Christophe, Dr GROETZ Jean-Emmanuel
Tous les auteurs :
Groetz JE, Ounoughi N, Mavon C, Belafrites A, Fromm M
Lien Pubmed
Résumé
We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™ and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.
Mots clés
Models, Theoretical, Radiometry, instrumentation, X-Rays
Référence
Rev Sci Instrum. 2014 Aug;85(8):083304