Design of radiosensitive gels and phantoms for irradiation assessment using MRI measurement: case of glottic cancer

Chemical dosimetry is a technique allowing tridimensional assessment of dose in radiotherapy. Magnetic resonance imaging provides 3D dose mapping of irradiated gels. Those gels are composed of an aqueous gel matrix containing radiosensitive compounds such as ferrous ions that are radio-oxidized or vinyl monomers that polymerize. There are specific requirements about soft-tissue equivalence that don't necessarily matched with MRI requirements, The differences between the parameters defining soft-tissue equivalence for the different gels are small enough to choose a gel not considering its tissue equivalence but considering its MRI T/sub 1/ or T/sub 2/ sensitivities, its linearity vs dose, etc. An important parameter to consider is the phantom morphology. Use of radiosensitive gels is interesting to simulate the irradiation of a part of the body with tissue/air interfaces and to study the 3D dose mapping in the case of a glottic tumor for example. Thus, it will be much easier to make that phantom if the gel is not oxygen sensitive.