Archive | 2019
Radiotherapy Dose Measurements Using a Fluorescing Quinine Solution
Abstract
Quinine solutions fluoresce when exposed to ionising radiation, through the production and absorption of Cerenkov radiation. This study evaluated the feasibility of using ‘household’ tonic water as a radiotherapy dosimeter. Tonic water samples were irradiated with static beams for a variety of energies and dose rates: 6 and 10 MV photons at 600 MU/min; 6 MV flattening-filter-free photons at 1400 MU/min; 6, 9, 12, 15 and 18 meV electrons at 400 MU/min and 6 meV electrons at approximately 2474 MU/min (used for total skin electron irradiation). A sliding window IMRT field was delivered using a 6 MV photon beam at 600 MU/min, to assess dynamic response. Fluorescence was successfully recorded using a monochrome low light CCD camera placed on the treatment couch as well as the treatment room visual monitoring system in the linear accelerator control area. Energy dependence and dose rate independence were observed. While limitations in the bit-depth and focal length of the camera prevented precise quantitative analysis of depth dose profiles for conventional dose rates (≤600 MU/min), performance for higher dose rates (in terms of signal-to-noise in depth dose profiles) was comparable to radiochromic film. Potential use includes measurement of dose in the build-up region, efficient checks of beam energy and tomographic reconstruction of 4D dose delivery, though further optimisation of fluorescent signal acquisition is required.