Study of the Optimal Composition and Storage Conditions of the Fricke–XO–Pluronic F–127 Radiochromic Dosimeter

Abstract

This paper presents the results of research on the Fricke–XO–Pluronic F–127 dosimeter. It consists of a Fricke dosimetric solution and xylenol orange (XO), which are embedded in a matrix of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F–127). Upon irradiation, Fe+2 ions transform into Fe+3, forming a colored complex with XO ([XO-Fe]+3). The color intensity is related to the dose absorbed. The optimal composition, storage conditions, and radiation-induced performance of the Fricke–XO–Pluronic F–127 dosimeter were investigated. The optimal composition was found to be 1 mM FAS, 50 mM sulfuric acid (H2SO4), 0.165 mM XO in 25% Pluronic F–127. The basic features of this dosimeter are discussed, such as dose sensitivity, linear and dynamic dose range, stability before and after irradiation, storage conditions, dose response for irradiation with 6 and 15 MV photons, and batch-to-batch reproducibility. The obtained results showed a certain potential of the Fricke–XO–Pluronic F–127 for radiotherapy dosimetry.

Impact of Salt on Thermal Stability and Dose Response of the Fricke-XO-Pluronic F-127 3D Radiotherapy Dosimeter

“…The irradiated sample was measured because it was observed for Pluronic F-127 gel (without other ingredients) that irradiation can influence the sol-gel transition temperature [ 28 ]. The dose was chosen to be higher, but close to the maximum of the dosimeter linear dose response based on the previous study [ 24 ]. The results are shown in Figure 2 and Table 1 .…”

“…In summary, there are similarities and differences between Fricke-XO-Pluronic F-127 with and without [ 24 ] NaCl, as follows: (i) both have similar dynamic and liner dose ranges, and a low dose threshold (lower than 0.5 Gy; so far not established); (ii) the composition with NaCl has greater dose sensitivity; without NaCl it is about 0.1316 ± 0.0022 Gy −1 cm −1 ; (iii) both respond similarly to irradiation with 6 and 15 MV photons (the composition without NaCl was not tested for dose response with 10 MV FFF photons and electrons); (iv) the addition of NaCl deteriorates the dosimeter’s storage stability; and (v) the conclusion of this and the former study [ 24 ] is that the dosimeter with and without NaCl should be kept at a low temperature (e.g., 4 °C) in the dark; eventually, in the dark at room temperature after irradiation.…”

“…The optical density was calculated as follows: Δµ = (ln(10)/x) × (AI – AU), where x = 1 cm is the length of the light path through the vial, AI is the measured absorbance of the irradiated sample, and AU is the absorbance of the non-irradiated sample; in both cases, the absorbance values at 585 nm were used for the calculations. The calculation of optical density was analogous to that used elsewhere [ 24 ] to ease comparisons with other radiochromic dosimeters.…”

“…Recently, a new Fricke-XO dosimeter with a matrix of poly(ethylene oxide)- block -poly(propylene oxide)- block -poly(ethylene oxide) (Pluronic F-127) [ 23 , 24 ] has been developed and described. Pluronic F-127 forms a physical gel characterized by a high degree of transparency and colorlessness.…”

Radiation‐sensitive nanogel‐incorporated Fricke hydrogel dosimeters with reduced diffusion rates

“…Along with the urgent practical needs, 3D dosimeters including Fricke gels, [5][6][7][8][9] polymer gels, [10][11][12] and radiochromic systems (PRESAGE, 13 tetrazolium salts-based dosimeters, 14 iodide-related gels, 15,16 etc.) have been developed rapidly in recent years.…”