Where does gel dosimetry fit in the clinic?

For over a decade our community has considered gel dosimetry a promising technique for the clinic, since it provides a unique methodology for three dimensionally dose measurement of the complex conformal dose distributions achieved by modern techniques such as Intensity Modulated Radiation Therapy. Even with improved gel dosimeters (such as normoxic polymer gel systems) and more accessible imaging for dose readout, this potential has not yet been fully realised. This may be because alternative tools have been able to more easily provide the technical and dosimetry quality assurance performed at specific steps in radiation treatment. The development of Adaptive Radiation Therapy is introducing complex processes for radiation treatment that depend on intricate links between various stages from imaging to treatment planning to radiation delivery, and back through loops depending to the level of adaptation. These links often involve human interpretation and intervention. Therefore, there is a greater need for comprehensive quality assurance of the whole radiation therapy process when adaptive techniques are first being developed, in regular quality assurance of the performance of these techniques within a radiation oncology program, and in independent outside credentialing of cancer centres by independent agents. I will attempt to make the case in this introductory paper to Dosgel 08 that this is the role uniquely served by gel dosimetry.