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Abstract

Medical Physics strides forwardThe majority of physics' applications in medicine may be said to stem from two discoveries at the end of the 19th century. In 1895 Roentgen discovered x-rays and in 1896 Becquerel discovered radioactivity. Subsequently, both of these discoveries resulted in fundamental changes in the way medicine was practised. X-rays have since been used to produce images of the inside of the human body and in the treatment of cancer, with radionuclides also being used for both of these purposes. The discovery of the electron by Thomson in 1897 was also to have a major impact on medicine with the subsequent development of electro-medical instrumentation.The use of x-rays to investigate the body resulted in the development of the field of diagnostic radiology. The use of x-rays along with the radiation emitted by radioactive decay for the treatment of malignant tumours resulted in the development of the field of radiotherapy or radiation oncology. Early estimates of the amount of radiation delivered to tumours were made by observing the skin redness that occurred after exposure. However, it was realized that more quantitative and precise methods were required to determine radiation doses. This led to the appointment of physicists to hospitals to develop techniques of radiation dosimetry. As the effects of radiation on the body became better understood it was necessary to limit the indiscriminate exposure of individuals to ionizing radiation. This resulted in the field of radiation protection.After the second world war numerous artificially produced radionuclides became available. As well as being used for the treatment of cancer, radionuclides were used to localize specific organs and diseases in the body. This resulted in the development of the field of nuclear medicine. With the development of digital computers it was subsequently possible to reconstruct cross-sectional images of the body, resulting in the 1970s in computerized tomography.As a further result of developments that took place during the second world war, ultrasound scanners were developed which enabled the foetus to be viewed during pregnancy using non-ionizing radiation. Another important development utilizing non-ionizing radiation was nuclear magnetic resonance, with the potential for magnetic resonance imaging being realized in the 1980s and subsequently becoming a major diagnostic tool.There are a number of exciting developments in medical physics which may in the future contribute to a greater under- standing of how the body functions. These include the use of SQUID (superconducting quantum interference devices) magnetometers and terahertz imaging. However, it remains to be seen what impact they will have in the medical field.A century ago the medical physics profession did not exist. Today, however, thousands of individuals work in this speciality throughout the world. Over the last 50 years there has been a growth of international organizations concerned with the application of physics in medicine. See the Web Watch on page 507.There is lots of interest in medical physics, and there are always students who want to know more. If a student wants a career in medical physics they would be advised to follow a BSc in Physics or Biomedical Engineering with a specific medical physics postgraduate degree. Further details regarding career opportunities may be obtained from the Web Watch links or from the author.Physics Education would like to thank guest-editor Alan Piercy for assembling this series of useful, interesting and informative articles covering a wide range of applications of physics in medicine. These articles bring us right up to date and point the way of developments in the 21st century. Clive Baldock Centre for Medical, Health and Environmental Physics, Queensland University of Technology, Australia E-mail: c.baldock@qut.edu.au