(Wednesday, 7/17/2019) 4:30 PM - 6:00 PM
Room: Stars at Night Ballroom 4
Prior to radiation delivery, a treatment plan is designed based on medical images acquired a few days to weeks before the start of treatment. Between treatment preparation and treatment delivery, as well as over the course of radiotherapy, the anatomy of the patient varies due to physiological processes such as bladder filling and respiration. In addition, the treatment itself induces heterogeneous tumor response and causes changes in normal tissue. Consequently, the actually delivered dose distribution may differ from the planned dose distribution affecting the probability of tumor control and normal tissue complications.
To improve the accuracy of treatment delivery and widen the therapeutic window of radiation therapy, Adaptive radiotherapy (ART) utilizes an imaging feedback loop, assessment of treatment variation and replanning. Both in-room imaging and simulation imaging can be utilized in an adaptive workflow. While in-room imaging has a logistic advantage and is essential for online adaptations, simulation imaging generally provides superior image quality. Moreover, functional imaging like PET is not available in the treatment room. With the introduction of integrated linac-MRI systems, both high quality anatomical and functional imaging becomes available for adaptive radiotherapy strategies. Image registration is a powerful tool to find a spatial relationship between the initial planning images and the repeated imaging. Such relationship subsequently allows for contour propagation, quantification of anatomical changes and treatment response and accumulation of the actually delivered dose. Adaptive strategies for anatomical changes aim to improve the initial treatment plan to account for anatomical changes. Both online and offline protocols are in clinical use with different trade-offs between workload and accuracy. Finally adaptive strategies to account for biological changes utilize imaging biomarkers to re-optimize the treatment plan to account for inter- and intra-patient variations in radio-sensitivity.
This course will provide an overview of the clinical rationale, imaging requirements and the role of image registration in adaptive radiotherapy. Moreover, current and future adaptive strategies for anatomical and biological changes will be described and elucidated.
Educational objectives
1. Understand the clinical rationale for adaptive radiotherapy
2. Understand the potential and limitations of different imaging modalities in the adaptive radiotherapy process
3. Understand the role of image registration for adaptive radiotherapy
4. Obtain an overview of the various adaptive strategies available for anatomically adaptive radiotherapy
5. Understand state of the art and future perspective of biologically adaptive radiotherapy
Handouts
Keywords
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Taxonomy
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