10.7795/120.20220324
Büermann, Ludwig
Ludwig
Büermann
Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 6.2, Dosimetrie für Strahlentherapie u. Röntgendiagnostik
The PTB free-air ionization chambers
Physikalisch-Technische Bundesanstalt (PTB)
2022
en
Physikalisch-Technische Bundesanstalt (PTB)
0000 0001 2186 1887
2021-11-15
2022-03-29
3235302 bytes
application/pdf
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Report
The fundamental quantity in the dosimetry of ionizing radiation is the absorbed dose to matter in units of J/kg with the special name of gray (Gy). The Physikalisch-Technische Bundesanstalt (PTB), the national metrology institute of Germany, is responsible for the realization and dissemination of the gray for x- and gamma radiation. The quantity air kerma is the metrological basis for dosimetry in radiation protection applications as well as in medical x-ray diagnostics and therapy. Air kerma for x-radiation is primarily measured using what are known as free-air ionization chambers (FACs). This technical report describes the definition of air kerma, the physical principles behind FACs, the technical design of three different FACs maintained at PTB, and the procedures and data needed to obtain the air kerma from the charge measured by FACs. This report is of general interest not only for researchers at other national metrology institutes who work with FACs but also for anyone who has air kerma calibration done for their secondary air kerma standards with traceability to FACs.
Dosimetry concepts and apparatus
X-ray detectors
Models and simulations
X-ray generators and sources
Radiation monitoring