Physics and engineering: milestones in medicine.

The history of the development of the applications of physics and engineering in medicine provides an insight into contemporary practice and can help to mould the future. Physics and engineering form a continuum, and, in the present context, engineering is indistinguishable from applied physics. The modern scientific era, which extends over 500 years, is characterised by numerous significant developments: for example, the Nobel prizes which most closely relate to physics and engineering in medicine were for X-rays and radioactivity, the electrocardiogram, the scattering of radiation, the cyclotron, nuclear magnetic resonance, the transistor, radioimmunoassay and computed tomography; and a medical physicist has received the Peace Prize. The origins and development of nuclear medicine, magnetic resonance and ultrasonic imaging are representative of the whole field. Physics and engineering rank alongside other medical sciences and underpin many of their applications. In what is now the developed world, human life expectancy has increased dramatically, but the costs and risks of modern medicine have meanwhile become a huge problem. The growing divergence of rich and poor is now arguably the greatest challenge. The future cannot be predicted, but the potential of physics and engineering to improve medicine has never been greater.