title: Characterization of a new ionization chamber in radiotherapy beams: angular dependence and variation of response with distance.
abstract: A new double faced ionization chamber was constructed at the Calibration Laboratory of IPEN. It has different collecting electrode materials: aluminum and graphite. It was irradiated in standard radiotherapy beams ((60)Co and X-rays). The response variation with distance and the angular dependence of this ionization chamber were evaluated. It was verified that the chamber response follows the inverse square law within a maximum variation of 11.2% in relation to the reference value. For the angular dependence it showed good agreement with international standards.
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP), São Paulo, SP, Brazil. josofisico@yahoo.com.br
authors.forename: Jonas O
authors.initials: JO
authors.lastname: Silva
authors.forename: Caldas
authors.initials: C
authors.lastname: Linda V E