This work describes the preliminary analysis of Fricke gels dosimeters
characterized by a new formulation making use of a matrix of polyvinyl
alcohol cross-linked by adding glutaraldehyde and analyzed by means of
nuclear magnetic resonance relaxometry. In previous optical studies, these
gels have shown promising dosimetric features in terms of photon sensitivity
and low diffusion of ferric ions produced after irradiation. In this work, we
used a portable nuclear magnetic resonance relaxometer to measure the
relaxation times (which are important for dosimetric applications) of these
gel materials. For this purpose, we performed a study for optimizing the
acquisition parameters with a nuclear magnetic resonance relaxometer. Gel
samples were exposed to clinical 6 MV photons in the dose range between 0 and
20 Gy. Nuclear magnetic resonance relaxometry measurements were per- formed
and the sensitivity to photon beams was measured for various values of the
Fe2+ ion concentration. The analyses pointed out that the MR signal increases
as the Fe2+ content in- creases and the increase is about 75 % when the
concentration of Fe2+ ions is increased from 0.5 mM to 2.5 mM. Furthermore,
the sensitivity improvement achieved with increasing the Fe2+ concentration
is about 60 %. This paper shows that the portable nuclear magnetic resonance
relaxometer used for analysis of porous materials can be used for
characterization of these dosimetric gels and this study can be considered as
the first step for the characterization of these dosimeters which in future
could be used for 3-D dose mapping in clinical applications.
The application of the Nuclear Magnetic Resonance Relaxometry method to express-study of rheological properties and composition of oil and gas condensate
