Low-Diffusion Fricke Gel Dosimeters with Core-Shell Structure Based on Spatial Confinement

Abstract

The diffusion of ferric ions is an important challenge to limit the application of Fricke gel dosimeters in accurate three-dimensional dose verification of modern radiotherapy. In this work, low-diffusion Fricke gel dosimeters, with a core-shell structure based on spatial confinement, were constructed by utilizing microdroplet ultrarapid freezing and coating technology. Polydimethylsiloxane (PDMS), with its excellent hydrophobicity, was coated on the surface of the pellets. The concentration gradient of the ferric ion was realized through shielding half of a Co-60 photon beam field size, and ion diffusion was measured by both ultraviolet-visible spectrophotometry and magnetic resonance imaging. No diffusion occurred between the core-shell pellets, even at 96 h after irradiation, and the diffusion length at the irradiation boundary was limited to the diameter (2–3 mm) of the pellets. Furthermore, Monte Carlo calculations were conducted to study dosimetric properties of the core-shell dosimeter, which indicated that a PDMS shell hardly affected the performance of the dosimeter.

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

“…For comparisons, the conventional Fricke hydrogels (PVA‐Fricke) and CHP nanogel‐incorporated Fricke hydrogels (CHP‐PVA‐Fricke) were irradiated under the same conditions. Absorbances at 585 nm of the samples were measured by a spectrophotometer (UV‐2550) to characterize the dose response properties, 33 and the response at each absorbed dose was expressed in the following form: average absorbance ± SD ( n = 3).…”

“…31 Inspired by superhydrophobic diffusion barriers, 32 improved Fricke gels based on core-shell structures were reported in our recent publication. 33 However, realizing the confinement at the submicron or even nanometer scale in Fricke gel dosimeters remains a challenge. Nanogels are 3D hydrogel materials at the nanoscale formed by cross-linked polymeric networks.…”

“…Our group prepared Fricke dosimeters embedded with multiple emulsion, and the diffusion coefficient was as low as 0.17 mm 2 h −1 31 . Inspired by superhydrophobic diffusion barriers, 32 improved Fricke gels based on core‐shell structures were reported in our recent publication 33 . However, realizing the confinement at the submicron or even nanometer scale in Fricke gel dosimeters remains a challenge.…”

Smart and Biomimetic 3D and 4D Printed Composite Hydrogels: Opportunities for Different Biomedical Applications

“…Noteworthy, PTT is used with some nanoparticles, which are capable of converting near-infra-red (NIR) electromagnetic spectra to heat, while PDT is a technique used with some molecules named photosensitizers (PS) for creating reactive oxygen species (ROS) [ 189 , 190 , 191 ]. Using ionizable agents under the influence of irradiation, by increasing the osmotic pressure of the intra-matrix hydrogel in combination with other materials, can be used for specific drug delivery systems [ 192 , 193 , 194 ]. Incorporation of chromophores into the matrix of hydrogels, changing a specific feature of the hydrogel, can be used for the early detection of cancer.…”

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

“…Numerous studies focused on different aspects regarding Fricke 3D dosimetry, including optimization of gel dosimeter’s formulae, stability, reproducibility, and dose response characterizations by using different radiation sources and reducing the diffusion of Fe +3 ions after irradiation [ 9 , 10 , 11 , 12 ].…”