ESTRO 2024 - Abstract Book

S78

Invited Speaker

ESTRO 2024

Overview: What is optimal adaptation and why is it relevant?

Iuliana Toma-Dasu

Karolinska Institutet, Oncology and Pathology, Stockholm, Sweden. Stockholm University, Physics, Stockholm, Sweden

Abstract:

Progress in medical imaging and response biomarkers has made the treatment adaptation one of the most discussed topics in contemporary radiotherapy. However, the adaptation of the treatment has so far been focused almost exclusively on the spatial dose distribution aiming mostly at ensuring that it is able to account for the patient-specific treatment variations during the treatment course. The most often encountered treatment variations considered by the common strategies for treatment adaptation are the daily patient setup and radiation beam placement errors, as well as the physiological and morphological changes of the target, organs and tissues within the treatment volume. The potential of adaptive radiotherapy, however, extends far beyond the increase of accuracy of radiation dose delivery to the target and the organs at risk as it could effectively increase the efficacy of radiotherapy by accounting for the patient-specific biological changes in the adaptive optimal control process. The aim of this talk will therefore be to introduce the concept of optimal treatment adaptation including the optimal stopping of the treatment in radiotherapy. Three key aspects for optimal treatment adaptation will be discussed. The first one is the spatial aspect aiming at assessing what sub-target volumes have to be chosen and how to achieve dose escalation or dose de-escalation in the context of treatment adaptation. The second one is the temporal aspect addressing the issue of the optimal time window for treatment adaptation and third one is the dosimetric aspect discussing the quantitative assessment of the dose to be delivered as a boost during the treatment adaptation in order to compensate for the insufficient or the lack of response of the target. These key points will be illustrated with clinical examples for non-small cell lung cancer and head and neck cancer patients.

3451

Patient specific QA for online adaptive radiotherapy

Sebastian Klüter

Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany

Abstract:

Online adaptive radiotherapy changes the paradigm of treatment plan verification, since online adapted plans cannot be verified by measurement while the patient lies on the treatment couch. The main question for patient specific QA in online adaptive radiotherapy is therefore: how can it be ensured that a specific treatment plan is correct and will be delivered correctly without the possibility of performing a measurement for this plan? In this talk, the role and aim of commissioning measurements as well as patient specific plan measurements will be discussed in the context of online adaptive therapy, and an overview over tools potentially helpful in online adaptive scenarios will be given.