Session Item

Positron emission tomography (PET), nowadays mostly performed together with computed tomography (CT), has an established role in cancer diagnostics and radiotherapy (RT) planning. Using the workhorse 18F-fluorodeoxyglcucose (FDG) as tracer, pre-treatment PET scanning may provide crucial information on nodal status and tumor extension that will impact radiotherapy planning. In this regard, many studies have shown how the introduction of PET in the RT planning process has resulted in significant changes in the treatment plan. PET has also been the main imaging modality for dose painting, which is an approach to locally escalate the dose to the presumably most aggressive part of the tumor. In the current work, we will discuss the use of PET in adaptive RT (ART). Here, the hypothesis is that PET will reveal treatment-induced functional changes in the tumor and possibly normal tissues that can be used to modify the treatment plan, in the end leading to better outcomes. As patients respond differently to treatment, this may be seen as a form of individualized RT where both treatment volumes and/or dosages may become altered. The use of PET in ART has not been extensively investigated, and we will also discuss studies monitoring tumor and normal tissues by PET during the course of fractionated RT. In addition to tumor targeting, potential sparing of organs at risk such as bone marrow and salivary glands will be considered. We will present progress in deep learning algorithms and their role in tumor autodelineation and ART. The future potential of using other tracers than FDG such as Fibroblast Activation Protein Inhibitor (FAPI) will briefly be touched upon. Finally, we will discuss a technical innovation in the form of an integrated PET/CT-scanner and linear accelerator, which may facilitate biology-guided and online ART.