Role of MRI in Radiation Oncology

Magnetic resonance (MR) images are used frequently in the diagnosis of disease and also in radiation oncology. In many disease sites, MR has unequivocal superiority over other imaging modalities. This chapter deals with the evolution of MR in radiation oncology. Due to superior soft tissue contrast, MR can visualize tumors more easily than other methods and can help reduce the treatment margin; thus, it may reduce radiation toxicity. MR-Linac is a combination device with a linear accelerator and an MRI unit on a single gantry. Since its inception in 2010, MR-Linac is increasingly used in radiation oncology and is entering the mainstream. This chapter provides a rationale for the use of MR imaging and more so for MR-Linac in radiation oncology and the associated pros and cons.