ABSTRACT
In clinical polymer gel dosimetry, a hydrogel is poured in a humanoid-shaped cast. The radiation-induced polymerization reaction results in the formation of highly cross-linked microscopically small polymer aggregates that are entangled with the gelatin hydrogel matrix that keeps them in place. The advantage of polymer gel dosimeters is that they can be easily poured in anthropomorphic-shaped casts such as a head cast, a head-and-neck cast, and a pelvic cast. Polymer gel dosimeters are hydrogels based on an organic gelling agent such as agarose or gelatin and contain vinyl monomers that on irradiation undergo a radiation-induced polymerization. At high conversions of monomers, the viscosity of a polymerizing system becomes very high. The water content of polymer gel dosimeters is generally in the order of 90%. If oxygen is present in the polymer gel during irradiation, peroxide radicals are created. These peroxide radicals will quickly react with other radicals leading to a termination.
