Characterization of the chemical and structural modifications induced by X rays on the HEMA based polymer gel

Abstract

The use of polymer gels in the radiation dosimetry field is rapidly increasing due to the possibility of 3 dimensional (3D) dosimetry. The aim of this study is to produce a new polymer gel with high dose sensitivity. This involved the production of polymer gel compositions containing different percentages of 2-hydroxyethyl methacrylate (HEMA) monomer and Di(ethylene glycol) dimethacrylate (DEGDMA) and 1-Vinyl-2-pyrrolidinone (VP) crosslinkers and these gels were irradiated with radiation dose between 0.5 Gy to 11 Gy, using 6 MV X-ray energy of the medical linear accelerator. The degree of polymerization was assessed by using magnetic resonance imaging (MRI) based on the R2-dose response. Then, Fourier Transform Infrared Spectroscopy (FTIR) analysis and Scanning Electron Microscope (SEM) images of the gels were taken. Polymer gels consisting of DEGDMA as crosslinker and Tetrakis (Hydroxymethyl) phosphonium chloride (THPC) as antioxidant were found to have a potential for use in radiation therapy dosimeter. The concentration of HEMA showing the most effective dose response was identified as 12 wt%. It was found that HEMA polymer gels containing DEGDMA crosslinker provide a better dose response than HEMA and HEMA-VP normoxic polymer gels.