Radiation dosimetry of polymer gel dosimeters using Raman microscopy

Full text: For several years polyacrylamide gels (PAGs) have been used for radiation therapy gel dosimetry. More recently FT-Raman spectroscopy has provided direct measurements of the concentration of monomers, post-irradiation, as a function of absorbed radiation dose. Adapting this work to Raman microscopy is an attractive proposition as it may enable dose to be measured to spatial resolutions of one micron. The composition of the PAG dosimeter was 3% acrylamide, 3% N,N'- methylene-bis-acrylamide, 5% gelatin and 89% water by weight. The PAG was irradiated from one end of a quartz glass slide of dimensions, 8 mm γ 38 mm γ 0.2 mm using electrons from a 6 MeV linear accelerator. Raman spectra were obtained using a Renishaw Raman microprobe with a nominal resolution of one micron. A helium neon laser operating at 8 mW and 633 nm was used for excitation. The depth dose measurement using the Raman microprobe compared to a calibrated ion chamber is illustrated. Raman microscopy of PAG dosimeters shows great potential in determining dose distributions with high spatial resolution and may have potential in areas such as cardiovascular brachytherapy. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine