Physicists from Liverpool University and clinicians from the Royal Liverpool University Hospital are leading the latest project at ALICE — a facility that is managed by the Science and Technology Facilities Council.
The aim of the research is to develop a diagnostic test for tissue obtained by endoscopy from patients with a precursor condition called Barrett’s oesophagus.
Barrett’s patients are at significant risk of developing full-blown cancer and are regularly monitored to detect changes in their condition. Despite this patients often present with tumours at an advanced stage, when surgical removal is no longer possible.
‘The problem is that even with the best histological techniques, it isn’t terribly accurate,’ Prof Weightman of Liverpool’s physics department told The Engineer.
Weightman previously performed preliminary work on oesophageal cancer at the Diamond Light Source accelerator at Harwell, but says that ALICE provides considerably more power.
One of its abilities is to produce an extremely intense, high-frequency source of infrared light through its InfraRed Free Electron Laser (IRFEL), enabling near-field imaging — also called scanning near-field microscopy.
This is based on the concept of forcing a wave of light through an aperture smaller than the wavelength of the electromagnetic radiation used.
‘When you’re working in the far-field the image is a long way away from the object you’re looking at, but in the near field you collect the light right up against the image, within angstroms of it,’ Weightman said.
‘We move a small fibre tip across the surface of the specimen using piezoelectric drivers and, since the fibre is hollow, we’re illuminating the specimen with the light from the free electron laser and this enables us to shine a lot of light on the specimen.’
The diameter of the fibre tip is 300 microns and the aperture 1 micron, and with a wavelength of light at eight microns the near field spatial resolution is 0.1 micron — far greater than the normal diffraction limit of four microns.
The precise ratio of DNA to glycoprotein in the sample can be inferred from the images produced, which has been shown to be a highly accurate signature of cancerous oesophageal tissue.
Prof Weightman said the latest ALICE measurements might be ‘overkill’ and suggests aspects of the technology could actually be scaled down for use in smaller devices, perhaps even directly in an endoscope. In this way ALICE acts as a testing bed for the potential of certain ideas.
‘Of course you do the experiment as well as you can and then you decide where you can start to reduce the constraints,’ Weightman said.
The team is also investigating using high-powered terahertz radiation from ALICE, which works differently from IRFEL by identifying specific resonating frequencies of cancer cells.