Acceptance tests for electrometers used in radiotherapy

Abstract

We present a set of tests designed to check the compliance of the requirements established in the standard IEC 60731:19972 and TRS 3981 technical report for “reference class” electrometers using the material normally available in a medical physics department. The characteristics under exam are: stability in the start-up, zero shift, zero drift, leakage current, linearity and repeatability. The method is applied to 4 electrometers: PTW UNIDOS, Sun Nuclear PC-Electrometer, Scanditronix-Wellhofer DOSE1 and Standard Imaging MAX4000. We checked that the electrometers comply with the requirements, although we detected some differences in the performance between them. The method proved itself precise enough and efficient to provide with reliable results for these tests and we consider it could be used to establish an internal procedure for the acceptance of this kind of equipment.