Using a dose-area product for absolute measurements in small fields: a feasibility study

To extend the dosimetric reference system to field sizes smaller than 2 cm  ×  2 cm, the LNE-LNHB laboratory is studying an approach based on a new dosimetric quantity named the dose-area product instead of the commonly used absorbed dose at a point. A graphite calorimeter and a plane parallel ion c...

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Bibliographic Details
Published in:Physics in medicine & biology 2016-01, Vol.61 (2), p.650-662
Main Authors: Dufreneix, S, Ostrowsky, A, Le Roy, M, Sommier, L, Gouriou, J, Delaunay, F, Rapp, B, Daures, J, Bordy, J-M
Format: Article
Language:English
Subjects:
absolute dosimetry
Calorimetry - instrumentation
Calorimetry - methods
Calorimetry - standards
dose-area product
dosimetric reference
Feasibility Studies
Graphite
Instrumentation and Detectors
Nuclear Experiment
Physics
Radiometry - instrumentation
Radiometry - methods
small fields
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Summary:To extend the dosimetric reference system to field sizes smaller than 2 cm  ×  2 cm, the LNE-LNHB laboratory is studying an approach based on a new dosimetric quantity named the dose-area product instead of the commonly used absorbed dose at a point. A graphite calorimeter and a plane parallel ion chamber with a sensitive surface of 3 cm diameter were designed and built for measurements in fields of 2, 1 and 0.75 cm diameter. The detector surface being larger than the beam section, most of the issues linked with absolute dose measurements at a point could be avoided. Calibration factors of the plane parallel ionization chamber were established in terms of dose-area product in water for small fields with an uncertainty smaller than 0.9%.
ISSN:0031-9155
1361-6560
DOI:10.1088/0031-9155/61/2/650