Evaluation of some dosimetric properties of a dedicated plane parallel ionization chamber for radiotherapy electron beams

Jonas Oliveira da Silva; Fernanda Beatrice Conceição Nonato; Francisco Glaildo Almeida Sampaio; Linda V. Ehlin Caldas

doi:10.15392/bjrs.v6i3.547

Authors

Jonas Oliveira da Silva Universidade Federal de Goiás
Fernanda Beatrice Conceição Nonato Centro Universitário Anhanguera de Santo André
Francisco Glaildo Almeida Sampaio Instituto de Radioterapia e Megavoltagem
Linda V. Ehlin Caldas Instituto de Pesquisas Energéticas e Nucleares, IPEN - CNEN/SP

DOI:

https://doi.org/10.15392/bjrs.v6i3.547

Keywords:

ionization chambers, electron beams, radiation dosimetry, radiotherapy

Abstract

Ionization chambers are the reference detectors for electron beam dosimetry. In this paper a dedicated radiotherapy plane parallel ionization chamber manufactured with low cost materials is presented for dosimetry in electron beams. The ionization chamber tested has a sensitive volume of 0.4 cm³, and the collecting electrode and the guard ring were painted with a homogeneous mixture of nail polish and graphite. The dedicated ionization chamber presented linearity of the response with the absorbed dose in the range of 0.5 Gy to 8.0 Gy, an increase of the response with the field size increasing, an angular dependence within ±5°, as recommended by international standards, and a polarity effect of 0.78% with the field size. From the results obtained, it is possible to conclude that the plane parallel ionization chamber tested in this work presents potential use for electron beam dosimetry in clinical routine.

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