Optical fibre radiation dosimeter for radiotherapy applications

A plastic optical fibre (POF) dosimeter for measuring ionising radiation during radiotherapy applications is presented. Previous initial results involving this type of sensor using an x-ray scintillating material have been reported by McCarthy et al[1]. This paper details results, using a different type of scintillating material (UKL65/L-R1-sourced from Phosphor Technologies in the UK)[2] which is better suited to higher energy radiation environments (such as in radiotherapy applications) coupled with an optimised sensor design. The sensor demonstrates excellent spectral response upon exposure from a Siemens Avant Garde linear accelerator under exposure from 6MV and 15 MV ionising radiation energy levels. Focusing on the spectral response peak of 544nm of the expected spectra for this type of scintillating material, and averaging the recorded intensity values at two wavelengths immediately either side of the peak wavelength, excellent repeatability of measurement upon repeated actuation of the radiation over short bursts of time is observed. The sensor also demonstrates very good stability of the response during the on-radiation periods, being a maximum of 2 % of the full scale value in each case.