Preliminary dosimetric characterization of EDBreast gel

Abstract

Purpose: EDBreast gel is an alternative Fricke gel dosimeter, read by Magnetic Resonance Imaging, in which sucrose is added to lower diffusion effects. This paper aims at determining the dosimetric characteristics of this dosimeter.
Methods: The characterization has been performed in high energy photon beams. The dose-response of the gel has been evaluated as well as its detection limit, its fading effects, the reproducibility of its response and its stability over time. Its energy and dose-rate dependence has been investigated, and the overall dose uncertainty budget established. Once characterized, the dosimetry method has been applied to a simple reference irradiation case in a 6 MV photon beam, with the measurement of the lateral dose profile of a 2 x 2 cm² field. The results have been compared with microDiamond measurements.
Results: In addition to its low diffusivity, the gel presents a high sensitivity, no dose-rate dependence considering TPR(20-10) values ranging from 0.66 to 0.79 and an energy response comparable to ionization chambers. However, its non-linear dose-response induces a high uncertainty on the measured dose (8 % (k=1) at 20 Gy) and reproducibility issues. The profile measurements displayed discrepancies compared to the microDiamond due to diffusion effects. The appropriate spatial resolution was estimated using the diffusion coefficient. 
Conclusion: EDBreast gel dosimeter presents interesting characteristics for applications in clinics, but the linearity of its dose-response should be improved to lower the uncertainties and to enhance the reproducibility.