What are the protection principles upon which radiation protection is founded

- May 23, 2019-

What are the protection principles upon which radiation protection is founded?

As previously noted, the human activities, such as those ranging from nuclear power production to radiation medicine,   that add radiation exposure to that which people normally receive due     to background radiation, or increase the likelihood of adding exposure    are termed practices. The human activities that seek to reduce the existing   radiation exposure, or the likelihood of incurring exposure which are not part of controlled practices (e.g., radon in homes) are termed interventions. 

For routine conditions involving practices,    most exposure of workers and members of the public is the result of normal  operating conditions. However, there may sometimes be variations in operating   conditions that cannot be regarded as normal. The term potential exposure  is used to describe exposure that is not certain to occur, (i.e., an exposure  caused by some departure from normality). Potential exposure reflects   the combination of the probability of occurrence of potential events,   the chance that such events will result in a radiation dose to individuals  and the probability of radiation effects from the expected resulting dose. 

Bearing these distinctions in mind,  radiation protection for practices is founded on a conceptual framework        proposed by the International Commission on Radiation Protection (ICRP)  and involves three principles: justification, optimisation and limitation. 

Justification . No practice involving exposures to radiation should be adopted unless it produces sufficient  benefit to the exposed individuals or to society to offset the detriment  it causes. In the case of justification, detriment is not necessarily  confined to radiation, but may include other social and economic considerations  as well. 

Optimisation . Once a practice has  been justified and adopted, it is necessary to consider how best to  use resources in reducing the radiation risk to individuals and the population. For any particular source, the broad aim should be that  the magnitude of individual doses, the number of people exposed, and   the likelihood of incurring exposure which is not certain (potential  exposure) should all be kept as low as reasonably achievable, economic  and social factors being taken into account. Because of the interaction of the various factors to be considered, methods for dealing with optimisation are diverse. They range from simple common sense to complex techniques  such as cost-benefit analysis. 

Limitation . Exposure of individuals  resulting from a combination of all relevant practices should be subject  to dose limits, or to some control of risk in the case of potential exposure. These are aimed at ensuring that no individual is subject   to radiation risks deemed to be unacceptable. Limits provide a clearly  defined boundary of individual risk for application of the more subjective procedures of justification and optimisation. 

Intervention involves the application  of radiation protection principles retrospectively, i.e., when it is decided to reduce existing exposure caused by an accident, contamination from past practices or high natural background which is amenable to being reduced.  Two principles are involved in the case of intervention: justification and optimisation. 

Justification          . The proposed intervention should do more good than harm, i.e., the reduction in radiation dose should be sufficient to justify the social   and economic costs involved. However, there will be some level of projected    dose for which intervention will almost always be justified because  of the acute radiation injury it will produce. 

Optimisation          . The form, scale and duration of the intervention should be optimised  so that the benefits of the dose reduction less its costs are maximised.  

The breadth of the conceptual framework for radiation protection has grown  constantly throughout the years, from the extremely simple guidance on  protection against X-rays issued in the 1930s up to the very comprehensive  system of protection which now covers practically all existing sources   of human exposure, artificial as well as natural, recommended by the ICRP in its Publication 60. Figure 3 depicts this coverage.