Dosimetry in modern radiation therapy: limitations and needs

摘要

As noted a number of times, the complex nature of the treatment planning and beam delivery required for IMRT, and the conformal nature of the resulting dose distributions, make dosimetry validation time consuming (although the new 2D array devices will likely increase efficiency of some tests). The challenge of dose verification will likely become more severe in the future, with the development of 4D radiation therapy to accommodate target motion, since the dosimetry validation will have to be done with phantoms undergoing motions mimicking those encountered clinically. Also, one can foresee a time when the intent of radiation treatment will be to irradiate parts of the target to variable non-uniform doses, perhaps because of information gained from biological/functional/molecular imaging [15,103]. Thus, the limitations of conventional dosimeters will likely increase with the further adoption of 4D IMRT and IGRT. This prospect, together with the attractive characteristics of gel dosimeters (such as high spatial resolution, tissue equivalence [104], direct 3D dose measurement, absolute and relative dose capabilities, etc.) spurred the development of gel dosimetry [67,86,105-107]. The possible role of gel dosimetry in IMRT validation is summarized also in table 1.