ESTRO 2022 - Abstract Book

S851

Abstract book

ESTRO 2022

a range of molecular and functional tissue properties. Together with post-processing tools, quantitative imaging biomarkers may be developed to measure a range of radiobiological tissue characteristics. These can be exploited to deliver more personalized radiotherapy to each patient, also having the possibility for adjustments during the course of treatment based on longitudinal changes in imaging parameters. The use of such biomarkers may therefore result in a more optimized treatment where the tumor response is improved, and the probability of normal tissue damage is decreased. This talk will provide an overview of how MRI and PET imaging biomarkers can be applied for personalized radiotherapy. One example is imaging biomarkers quantifying intratumoral heterogeneity. Such information is largely ignored in radiotherapy planning today. Quantitative imaging biomarkers enable voxel-wise spatially defined mapping of biological characteristics, providing an opportunity for optimized radiotherapy dose distributions. Changes in imaging biomarkers during or after radiotherapy offer the possibility for adaptation of treatment during the course of radiotherapy, or early detection of disease recurrence. Quantitative imaging biomarkers can provide objective decision-support tools in personalized patient management. To fully exploit the potential that lies in quantitative imaging biomarkers there is a need to reduce uncertainties through standardization of image acquisition and parameter quantification. Further, one needs to conduct prospective clinical imaging studies at multiple centers to achieve data from large patient cohorts that allow appropriate validation of methodology and biomarker results as well as the possibility to ensure reproducibility and repeatability of the biomarkers. Currently, there is a paucity of evidence on how quantitative imaging biomarkers potentially affects clinical decision- making and long-term patient outcome, highlighting a need to collect long-term survival data through prospective imaging biomarker studies. In the talk, examples will be shown on how multicenter quantitative imaging biomarker studies with PET and MRI in radiotherapy can implement standardized protocols and phantom studies to reduce uncertainties in parameter quantification. The presentation will end with an outlook on recent progress within physics-informed models for quantitative imaging biomarker development, and how quantitative imaging data can be implemented into the concept of digital twins in order to improve personalized radiotherapy.

SP-0970 The Radiation Oncologist

C. Fuller

USA

Abstract not available

SP-0971 The RTT

V. van Pelt 1

1 NKI-AVL, Radiotherapy, Amsterdam, The Netherlands

Abstract Text

Innovations in radiotherapy practice continue to develop. With the introduction of integrated MRI-guided radiotherapy (MRIgRT) systems, such as hybrid MRI-linear accelerators (MR-linacs), the role of the RTT is changing. There is a need for RTTs to expand their range of tasks and responsibilities, as radiation oncologists and other specialists do not have time to fulfil all tasks that are required in an online setting. For example, RTTs increasingly are involved in online target delineation, online re-planning, and analysis of (functional) MR images. Daily functional imaging on an MR-linac provides the opportunity to measure changes in tumor biology during treatment. These changes can be used to adapt the treatment, in a process called biological image-guided adaptive radiotherapy (BIGART). We are now at a point where we are collecting data in clinical trials to determine which qMRI parameters change during treatment and assess if those changes are related to clinical outcome with the aim of identifying prognostic qMRI biomarkers. The implementation of these functional imaging sequences into clinical scan protocols is a collaboration between the RTT and the researchers. The RTT has the practical insight to integrate this in to the workflow as efficiently as possible and the researcher brings the expertise of functional MRI. Together, they determine for each treatment type how much time is available in the adaptation phase and which functional sequences can be added to the MRI protocol on the MR-linac without extending the treatment time for the patient. Also in the analysis of functional MR images there is a role for the RTT, such as delineation of the tumor, calculation of quantitative parameter maps and calculating statistics of these maps. By involving RTTs in the acquisition and analysis of (functional) MR images, clinical practice and research become connected. This is important to improve research on relevant clinical topics as this will strengthen the clinical relevance of the research and and create a more efficient path from research to clinical implementation.

SP-0972 The imaging expert: The use of (imaging) biomarkers in AI prediction models of outcome

Á. Alberich Bayarri 1

1 Quibim , Quibim, Valencia, Spain