Theme 2Focused energy delivery and motion compensation
Theme 2: Focused energy delivery
Focused energy delivery is aimed at destroying tissue and is mostly used to treat cancer (e.g. using photons, protons or focussed ultrasound). However, focused energy delivery is also used to sensitize tissue for drugs or other treatments (photodynamic therapy, hyperthermia) and to induce targeted drug delivery. A main limitation of external focused energy delivery is organ motion causing discrepancies between planned and executed location of the energy delivery potentially damaging healthy tissues.
The overall aim of the theme is to deliver workflows that optimize the precision of energy delivery while remaining practical in terms of workload and patient throughput. As the precision increases safety margins can be reduced limiting damage to neighbouring healthy tissues and increasing therapeutic ratio.
To realize this aim, target definition and treatment planning must be optimized (collaboration with WP1), real-time or near real-time imaging must be implemented to allow updates to the treatment plan based on the situation of minute or day (collaboration with WP3), fast image analysis and plan updating must be available (collaboration with WP1), and uncertainties in the process must be understood and minimized (collaboration with WP4).
The following are the main challenges that must be addressed in WP2:
- Provide representative planning imaging
- Quantify motion on different time scales from planning imaging
- Properly delineate the target and its potential microscopic extents and organs at risk (includes training)
- Accurate planning to avoid healthy tissues and be robust against small errors
- Optimize intra-operative imaging, e.g. motion compensation
- Register intra-operative imaging to planning imaging
- Safe and efficient adaptation based on intra-operative imaging (energy steering)
- Monitor motion during delivery process and adapt if needed
- Evaluate residual uncertainties in the process
- Calculate the delivered energy taking the uncertainties and residual motion into account
- Evaluation of the clinical outcome in relation to the actually delivered energy
- Optimize workflows for speed, simplicity and safety
In this project, existing collaborators are with UCL (motion compensated imaging), Leeds (optimization of workflows for stereotactic radiotherapy, evaluation of outcome vs dose), Oxford (optimization of workflows for proton therapy), and the Royal Marsden Hospital (MR guided radiotherapy).
Marcel Van Herk
Professor Marcel van Herk is the chair in radiotherapy physics at the University of Manchester.
He is currently setting up a research group focussing on improving the accuracy of radiotherapy. As his work heavily involves implementation of research into clinical practice, he has an honorary appointment at the Christie.