title: Using a dose-area product for absolute measurements in small fields: a feasibility study.
abstract: 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%.
authors.affiliation: CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), F-91191 Gif-sur-Yvette, France.
authors.forename: S
authors.initials: S
authors.lastname: Dufreneix
authors.forename: A
authors.initials: A
authors.lastname: Ostrowsky
authors.forename: M
authors.initials: M
authors.lastname: Le Roy
authors.forename: L
authors.initials: L
authors.lastname: Sommier
authors.forename: J
authors.initials: J
authors.lastname: Gouriou
authors.forename: F
authors.initials: F
authors.lastname: Delaunay
authors.forename: B
authors.initials: B
authors.lastname: Rapp
authors.forename: J
authors.initials: J
authors.lastname: Daures
authors.forename: J-M
authors.initials: JM
authors.lastname: Bordy
mesh_terms: D002151:Calorimetry / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D005240:Feasibility Studies; D006108:Graphite; D011874:Radiometry / Q000295:instrumentation / Q000379:methods
chemical_list: D006108:Graphite