In a keynote lecture at the recent IUPESM World Congress in Toronto, Wilson shared the details of this presentation with the conference delegates. "Biophotonics is the convergence of optical and life sciences," he explained, describing how photonics can impact areas such as analytics, diagnostics and therapeutics. Indeed, optical devices are used in the clinic today to detect colon tumours, guide surgical excision, perform laser surgery, diagnose dermatological conditions and far more.

Affordable light-based technologies also play a key role in meeting global healthcare challenges. As an example, Wilson described his research team's development of a mobile phone-based fluorescence imager that detects bacteria in infected wounds and guides the clinician to areas requiring decontamination prior to bandaging. "A clinical trial showed that this makes a significant difference in terms of outcome, and it is now being commercialized," he noted.

One driver of the biophotonics progression is the transfer of technologies from other photonics domains. Technology for high-sensitivity night goggles, originally created for military use, has been applied to develop real-time near-infrared imaging devices that can assess lymphedema after breast cancer surgery. Elsewhere, high-frequency ultrasound designed for telecoms applications has helped progress optical coherence tomography (OCT) into a standard tool for retinal imaging.

Another biophotonics driver is convergence with other established and emerging sciences, such as nanotechnology, imaging, robotics and molecular biology. Examples here include nanostructured optical biosensor chips for rapid influenza detection, fluorescence-enabled surgical robots, and the merging of real (optical) and virtual (X-ray) endoscopy. "There is tremendous convergence between molecular biology and biophotonics, most of the focus of which is on fluorescent proteins for imaging gene expression," Wilson added.

Global challenges

Wilson next described some of the global healthcare barriers that photonics may help overcome. These include scientific and technical challenges, as well as socio-economic, geographic and cultural issues. He described the problems surrounding cervical cancer screening in Africa. Early detection of cervical cancer is key to effective treatment, but in many countries the high cost of colposcopic instruments, combined with women's fear of examination and a lack of female doctors, means that screening just doesn't happen.

As a result, the death rate is ten times higher in Africa than in the USA, leading the World Health Organization to state that "cervical cancer is an avoidable cause of death among women in sub-Saharan Africa". So how can optical technologies help? Wilson described trials starting in India and Nigeria in which a woman can use a tampon-based colposcope herself and then send the resulting image away for analysis. "This is a beautiful example of technology translation to meet a real clinical need in global health," he said.

Another case in point is China, the world's largest producer and consumer of tobacco and a country in which nearly 60% of male doctors smoke. With nearly 350 million Chinese smokers, how can the potential future tens of millions of patients be treated? Without the infrastructure to perform radiotherapy or surgery, the practical answer may lie in light-based therapeutics.

Take it to the extreme

Wilson pointed out that one of earliest Nobel prizes for medicine was awarded for light based therapy, in 1903. But he added that, in terms of exploiting the full potential of photonics for biomedical applications, "I think we're just beginning". He looked at some "extreme" applications that may become reality in the future.

Extreme photonics technologies for bio applications include attosecond photonics: imaging with light pulses that are so short they can effectively "freeze" atoms in time. Or the exploitation of entangled photons – Einstein's "spooky action at a distance" – to create a visible light microscope with X-ray-like resolution. Indeed, a paper has already been published in which the world's first entanglement-enhanced microscope successfully imaged a 17 nm structure.

On the flip side, there's the idea of "extreme bio" using photonics. One example is optogenetics: using light pulses to stimulate firing of neurons engineered to respond to light. Wilson showed a video in which a mouse's movement was controlled by using light to activate brain circuits related to motion. So could this scale to humans? It is technically possible, he said, but will face enormous ethical challenges.

Wilson concluded by pointing out that only a small percentage of the papers presented at the World Congress covered optical techniques. He attributed this to the fact that biophotonics tends to be more aligned with the optical community rather than the medical physics community. "The big question now is 'will medical physics see the light?'," he said.

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