Writing in the journal Australasian Physical & Engineering Sciences in Medicine, Ng examines the current status of the field (Australas. Phys. Eng. Sci. Med. 31 85). He suggests that while radiation delivery techniques - such as intensity-modulated and image-guided radiotherapy - can now provide almost optimal dose distributions, today's challenge lies in precision delineation of the target volume. What's needed now, he says, is "a new direction, so that oncology can exploit cutting-edge developments in imaging to bring about significant improvements in targeting accuracy, dose distribution and clinical outcomes for cancer treatment". For this reason, he argues, the current technology focus must be upon image-guided treatments.

As such, the next development task for medical physicists will be the convergence of imaging and therapy - two disciplines that have been divided for the past 50 years into separate, specialized, self-contained professions. Ng cites the example of PET/CT, an imaging technology that's proven highly effective in treatment planning but which now needs efficient and cost-effectively integration into the radiotherapy workflow. One obstacle here is that PET/CT facilities are generally located in a nuclear medicine or imaging department, while radiation therapy is usually provided in a quite separate department.

Thus Ng predicts that this reconciliation may not be a straightforward task. Bridging the gap will require ventures such as cross-disciplinary research networks comprising expert groups from both fields; common workshops, seminars and conferences; collaboration on education and training among relevant professional and learned societies; as well as the co-operation of sister organisations from radiology, oncology, biomedical engineering and other related clinical specialties.

Future focus
The cost-containment emphasis of today's health care systems translates - at the medical physicists' level - to a drive towards developing specific skills and competencies, be they in radiation oncology physics or diagnostic imaging physics. Such "overspecialization" by the profession could, however, come at the expense of future opportunities, such as those created by translational and frontier research. Ng raises the concern that this tightly focussed approach could affect the ability of the next generation of medical physicists to respond to new technologies and the changing medical landscape.

What's more, as hospitals start to embrace alternative treatment regimes - such as catheter-guided radioactive particles, high-intensity focused ultrasound, photodynamic therapy or radiofrequency and microwave ablation - medical physicists must consider the role that they can play in implementing these technologies, which do not traditionally fall under radiology or oncology departments.

Another change that must be addressed is the impact of human genome research. Advances in this field have provided an extensive knowledge base with which to change the nature of imaging from diagnosis and disease recognition to prediction and prevention. Molecular imaging is also developing rapidly - with PET/CT, PET/MRI, optical imaging and other modalities improving the early detection and treatment of disease. Here again, medical physicists have an important role in validating these innovative treatments.

However, says Ng, the blurring lines between disciplines could also lead to be increased uncertainties and turf battles among the medical specialties, with medical physicists likely caught in between. Nonetheless, he thinks that the outlook for the community is encouraging, with physics providing the foundation for many breakthrough technologies that will ultimately find application in areas such as cancer, stroke and brain disorders, cardiovascular diseases, minimal basic intervention and decision-support systems.

So how can medical physicists ensure that their role stays relevant throughout this changing environment? For starters, says Ng, they must become actively involved in the task of health promotion and disease management, exploiting their foundation in mathematics, statistics, physics, engineering, anatomy and physiology to work alongside their medical colleagues. Medical physicists already contribute significantly by transforming laboratory advances into clinical applications, and they can help their colleagues further by investigating and evaluating the outcomes of therapeutic or diagnostic modalities. He notes that the medical physics profession should not abandon basic scientific research, without which there would not be any progress.

Ng emphasises that besides having a high level of scientific knowledge, future medical physicists will need to acquire a range of new skills - including computing prowess and the creativity to think beyond the confines of their own discipline. The medical physicist of the future should possess: high ethical standards and the ability to take responsibility for decisions; an enquiring mind and problem-solving skills; excellent oral and written communication skills; and the ability to reassure nervous patients. They'll also need to keep up to date with science in general, talking to colleagues within biochemistry, molecular biology and engineering departments to cross-fertilise ideas and fuel the physicists' imaginations.

"Curiosity breeds new ideas," says Ng. "Probing the minds of medical doctors will bring to light the problems that they encounter that medical physicists may help to solve." He concludes that for medical physics to remain relevant in 2020, it's vital that the disciplines of imaging and oncology come closer together and that the profession looks towards a multi-talented, multi-skilled future. "Never have the opportunities been greater for medical physicists to contribute to the wellbeing of patients around the world," he says. "To me the future is clear: To achieve more, we should imagine together."

• Kwan-Hoong Ng's commentary paper, Medical Physics in 2020: Will we still be relevant? (Australas. Phys. Eng. Sci. Med. 2008 31 85), was initially presented as the John Cameron Memorial Lecture, delivered at the 5th Southeast Asian Congress of Medical Physics (SeaComp'07) in Manila, the Philippines.