Rigorous computational modelling of the optical detection of ultrasound waves for medical imaging
Photoacoustic imaging is an emerging imaging technique based on the optical generation of ultrasound waves in tissue. It has potentially broad application both for guiding interventional procedures such as those used in oncology, fetal medicine and neurology and as a non-invasive imaging modality for the clinical assessment of diseases including cancer. We have developed a novel optical ultrasound sensor based on a Fabry Perot (FP) interferometer for detecting photoacoustic signals. The highly versatile sensor can be used to realise a variety of miniature endoscopic photoacoustic devices and non-invasive imaging scanners. Furthermore, it provides superior acoustic performance compared to the piezoelectric receivers conventionally used to detect photoacoustic signals; see Nature Photonics 9, 239-246, 2015 for examples of the exquisite images that it can provide.
However, the sensor’s penetration depth is currently limited to approximately 10mm. There is significant scope to improve upon this by increasing its optical sensitivity, thus extending the forward “viewing range” of endoscopic probes used to guide interventional procedures and opening up new deep tissue imaging applications, such as the non-invasive assessment of breast cancer and metastatic nodal disease.
The aim of the project is to achieve this sensitivity improvement by developing the first computational optical model of the FP ultrasound sensors based on Maxwell’s equations. This will enable unexplained experimental results to be explained, and the next generation of high sensitivity sensors to be developed through in silico prototyping of novel sensor geometries and interrogation beam types. The model will be use to design an optimised sensor for providing increased penetration depth for photoacoustic devices used for guiding interventional procedures and non-invasive imaging. This project would suit students with a background in mathematics, physics or electrical engineering. The project will be largely theoretical/computational, however, an optional aspect of this project is performing experiments to validate the developed model.
The proposed sensor has many potential applications within the clinical research theme of cancer imaging. These include guiding the surgical resection of malignant nodes and tumours using endoscopic devices as well as the non-invasive assessment of breast cancer and metastatic disease in lymph nodes. The generic nature of the technology suggests it would also find application in fetal medicine, neurology and cardiovascular medicine particularly for guiding interventional procedures.
This project involves the formulation and computational implementation of a numerical model of the optical response of the probe and thus aligns with the computational modelling methodological research theme.