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

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. Both the collecting electrode and the guard ring were painted with a homogeneous mixture of nail polish and graphite. The dedicated ionization chamber presented a linear response with electron absorbed dose within the range 0.5 to 8.0 Gy, an increase of its response with the field size increasing, an angular dependence within ±5°, as recommended by international standards, and a polarity effect of 0.78% according to the field size. Considering the results obtained, it is possible to conclude that the plane parallel ionization chamber tested in this work presents potential use for elec - tron beam dosimetry in clinical routine.