Radiotherapy, mainly used in the treatment of cancers, has long been closely linked to the use of medical images, particularly when it comes to dosimetric treatment planning in line with doctors' prescriptions. The aim is to determine the ballistics of the irradiation in order to respect the dose constraints delivered to the tumor zone and to healthy tissues, with the aim of treating the cancer while limiting any undesirable effects. From its very beginnings, radiotherapy has been caught up in this quest to sculpt the dose - known as conformation - to the area to be treated. As treatment precision depends on both the physical means used to deliver the dose (particle type, collimation methods, etc.) and the ability to localize the area to be treated, there have been significant developments in both these aspects.
After introducing the context of radiotherapy and its basic notions and issues, we will see how imaging has gradually migrated from dose planning alone to a much broader use throughout the treatment. Target localization and tracking when the target is mobile are at the heart of the use of imaging in radiotherapy, with a strong emphasis on multimodal image fusion and modeling. This will be illustrated by a presentation of various studies carried out in France and abroad over the last two decades.
