Book 4: Use of radiation in research

7.1 Introduction
It is a general principle that the benefits of ionising radiation and radionuclides in medicine should outweigh the risk. Hence it is necessary to describe the risks and benefits of the proposed irradiations, noting whether the benefits are general, or specific to the people being studied. The description of the risks must include a quantitative estimate of the absorbed radiation dose and the means whereby exceeding any maximum dose will be prevented.

While irradiation of humans in medical research presents certain calculable risks, such irradiation, when properly controlled, carries a much smaller risk to health than many chemicals, pharmaceuticals and other agents in common use. Appreciable radiation exposure may sometimes be unavoidable in medical research, but the collective total exposure of people to irradiation for research purposes is normally considerably smaller than that incurred by the regular use of radiological procedures in diagnosis and therapy, and is frequently less than environmental exposure.

Non-ionising radiation is generally considered to be safe, but this assumption may not be valid for newer techniques. When these techniques are used in research projects, the issue of safety must be specifically addressed.

The International Commission on Radiological Protection (ICRP), established in 1928 by the International Congress of Radiology, has published comprehensive recommendations on the protection of man from ionising radiation, including recommendations on exposure in the context of medical research.11 In addition, the World Health Organisation published a report on the use of ionising radiation and radionuclides on human beings for medical research, training and non-medical purposes.12 The guidelines formulated by the South African Forum for Radiation Protection, as set out here, are based on the recommendations of these two bodies and are endorsed by the MRC.13 These bodies have also indicated methods for calculating absorbed radiation doses.

7.2 Types of research
7.2.1 Research involving radiopharmaceuticals
This type of research will involve the use of agents labelled with a radionuclide in order to evaluate their biokinetic behaviour. In some instances the radionuclide may be administered separately from the agent. Imaging of the subject may sometimes be necessary to assess the action of the therapeutic or other agent being used.

7.2.2 Research on new diagnostic applications
Most of this research is incidental to the irradiation of patients in the course of diagnosis and treatment, but it is sometimes necessary to evaluate normal subjects as well. The establishment of medical and biological reference values, based on an adequate selection of known normal individuals, provides standards against which abnormalities can be judged. However, this should not include paediatric patients unless certain specific conditions, described below, are met.

7.2.3 Treatment
The principles to be applied are essentially that (1) the therapeutic benefit should outweigh the risk and (2) the exposure should achieve a positive outcome while minimising side-effects (ALARA as low as reasonably achievable). In all cases, exposure should be based on Good Clinical Practice, whether it involves diagnosis, localisation, irradiation of the target, or minimising damage to the surrounds of the target and all other non-target regions.

7.2.4 Other research
This category covers studies in physiology, pathology and anthropology and includes studies on volunteers. It involves the use of compounds labelled with radioactivity to investigate, for instance, iron absorption, the fate of food additives and pesticides that are swallowed or inhaled, or injectables.

It includes research of epidemiological importance, and case-finding work in the field of industrial medicine and occupational health. It also involves patients being treated for various conditions, such as cancer, where radiation is a part of therapy.