The demand for hypofractionation and higher plan conformality since the last ten years resulted in an inevitable increase in plan complexity and concerns about their robustness. This pushed to an escalation in frequency and doses of the imaging procedures, in order to ensure a submillimetre patient setup and a constant monitoring along the treatment delivery.
The requirement for three-dimensional, frequent, and even time-resolved imaging led to the spread of non-radiographic imaging modalities, like optical or thermal surface-based techniques.
Optical surface imaging can be performed using different technologies like laser scanners, time-of-flight-, stereovision-, or structured-light-cameras, and is already part of the routine of many departments. Their main use has been patient positioning and motion monitoring [Hosaik,2020]. The major benefits are the non-invasive real-time feedback of the patient surface, thanks to a high spatial and temporal resolution, ally to an interface with the main linac vendors. The large field-of-view and the constant development of new characteristics (as e.g. Cherenkov imaging [Jarvis, 2021]) promises an acceptance and adoption as standard imaging technique.
In contrast, thermal imaging uses the temperature pattern of the patient’s surface and is still a recent technology in the field of radiotherapy. The two main applications known are for the monitoring of patient’s motion and physiologic-processes. This technology promises motion detection without the impact of room lighting, skin tone, or clothing. Regarding the analysis of the treatment efficiency, the main reported application, due to its anatomical position, is breast radiotherapy. Here variations in temperature and vascular patterns might be used as feedback of the treatment effectiveness [Baic, 2021; Hoffer,2018].
In this session, these two modalities, with a focus on motion management applications, are going to be explored, from the overview of the current state of the art, challenges, and clinical examples.