Gel dosimetry: MRI

While a vast amount of scientific literature is available on the topic of gel dosimetry with MRI readout, this wealth of information may seem at first overwhelming for medical physicists and newcomers in this rapidly evolving field of research. With this review, my mission is to streamline the wealth of information in the scientific literature and provide a quick guideline for those making their first steps in implementing gel dosimetry in a clinical environment, while still providing a lookout to new and emerging evolutions in the field. In a first section, the physical mechanisms behind the MRI contrast are briefly explained for both Fricke gels and polymer gels. In a subsequent section, an overview is given of the different MRI pulse sequences and pulse sequence optimization will be discussed. Emphasize is placed on the framework and formalism to calculate optimal parameters. The reliability of MRI-based polymer gel dosimetry will be discussed, and a quick beginner's guide is provided. Finally, a lookout to new and future developments of polymer gel dosimetry will be given.