Fricke gel dosimeters have great potential for three-dimensional (3D) dose verification in radiation therapy; however, they suffer from time-dependent ion diffusion after irradiation, severely affecting their stability and reliability. In this work, a pullulan-based amphiphilic molecule was synthesized, characterized, and self-assembled into nanogels. Nanogel structures were embedded into gel dosimeters to reduce the diffusion rates, and radiation-sensitive nanogel-incorporated Fricke hydrogel nanocomposites were prepared successfully. The results demonstrated that the diffusion coefficient of improved dosimeters was reduced to 0.125 ± 0.001 mm 2 h −1 , while maintaining the high optical dose sensitivity (0.0410 ± 0.0004 Gy −1 cm −1 ). It provides a powerful tool toward the practical application of 3D dosimeters.
The irradiation of tumors in radiotherapy requires accurate 3D dosimetry. The Fricke 3D dosimeters, which were considered to be high potential of application in 3D dosimetry, suffer from a reduced temporal integrity of dose distribution caused by Fe 3+ ions diffusion. To overcome the drawback, we firstly synthesized a kind of amphiphilic molecules with critical micelle concentration of 0.45 g/L and hydrophile-lipophile balance value of 10, then prepared multiple emulsions by self-assembling those molecules in Fricke solution under liquid paraffin, and finally obtained Fricke hydrogel embedded with the multiple emulsions. The diffusion coefficient of Fe 3+ ions in the embedded Fricke hydrogel was measured to be 0.17 mm 2 /h. The hydrogel dosimeter exhibits considerable potential for use in dose verification applications.
Li Jiang,Chengfang Zhang,Xinyue Xu,Rui Hu,Ping Zhang,Rensheng Wang,Xinjian Chen,Liang Hu
Dose verification in radiotherapy is crucial to ensure a safe and efficient outcome of medical treatments. To overcome routine radiation dose detection challenges, a composite hydrogel sensor comprised of fluorescent poly( N -isopropylacrylamide)-based nanogels and clay nanoparticles is reported. The sensing methodology is primarily based on the transition of hydroxyphenyl fluorescein to fluorescence in the presence of OH radicals due to the radiolysis of water molecules under ionizing radiation, whereas the fluorescence intensity of 5(6)-carboxytetramethylrhodamine is stable upon radiation. Harnessing the ratiometric fluorescent strategy, in vitro point- and topographical-dose profiles under X-ray and electron beam irradiation and the in-vivo determination of γ-ray dose are determined without any waiting time after irradiation. The determined dose is comparable to the results of Monto Carlo simulations and clinical treatment planning systems (TPS). Also, the sensing capability of the developed sensor is well maintained, regardless of the types of radiation, dose rate, radiation energy, testing temperature, and storing period. Hence, our sensors show the translational potential for dose verification in radiotherapy.
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