Aims of the Project:
- Demonstrate the feasibility of high-resolution tracking of individual radiolabelled particles (PEPT) for applications in biomedicine
- Fully characterise the precision and accuracy of PEPT in pre-clinical models, including determination of the optimum acquisition and processing parameters
- Implement, evaluate and optimise algorithms for tracking multiple particles simultaneously
Standard radionuclide imaging involves imaging the distribution of a radiotracer in the body. In Positron Emission Particle Tracking (‘PEPT’) a single particle labelled with a large number of radioactive nuclei would be injected into the body (eg into the bloodstream) and tracked dynamically. Tracking of positron emitting particles has previously been used in numerous industrial applications in order to measure flow distributions or investigate how materials mix. These industrial applications were pioneered at Birmingham University who have demonstrated that it is possible to track (single) positron emitting particles with acceptable spatial and temporal resolution to obtain fluid velocity maps with particles travelling at speeds up to 1 ms-1 if the particle has a radioactivity of ~ 100kBq . A simple triangulation technique is used to perform the tracking.  Other than some limited cell tracking measurements performed at Stanford University , the feasibility of using PEPT in biomedical applications has not been investigated. As part of a joint programme with the Birmingham Group, we propose to try and use PEPT to measure blood flow related information in-vivo – potentially this can be done with very high resolution (~1mm for PEPT cf 5-10,m for PET). A key requirement for in-vivo PEPT is the availability of very high-specific activity radiolabelled nano-particles , such as have uniquely been developed by Rafa Torres at KCL. Potential clinical applications include measuring properties of blood velocity profiles in the presence of stenoses, characterising micro-vascular disease in the heart and tracking blood and immune cells in the body.
In principle, PEPT can be perfomed on any standard PET scanner, and the method is likely to be relevant in the context of ‘total body PET’ a revolutionary technique for human PET imaging, but before this can be evaluated many basic parameters must be examined. The feasibility of potential clinical applications depend on the accuracy with which measurements can be made. Given the experience of the Birmingham group it is very unlikely that the technique will not work to some degree in a small animal models but whether useful measurements, such as would form the basis for eg measurement of blood flow, can be made with an accuracy that makes them clinically useful is at this point totally unknown. Implementing PEPT in vivo and extracting clinically useful information involves many additional technical and computational challenges to those encountered in industrial applications, notably the need for multiple particles and dealing with the effects of subject motion – these will be addressed in this project.
The PhD-candidate should preferably have a background in physics/engineering/computer science and ideally be interested in a project that has both experimental and computational aspects which must be developed in parallel. This project provides the opportunity to have an impact on a novel imaging modality at a very early stage when many fundamental aspects of how it will work are still to be defined.