Basic principles of radiological protection

The system of radiological protection by ICRP for proposed and continuing practices is based on the following general principles  

The ordering of these recommendations is deliberate the ICRP limits are to be regarded as backstops and not as levels that can be worked up to. 

For workers, the effective dose limit recommended by ICRP is 20mSv per year averaged over defined periods of 5 years with no more than 50 mSv in any single year, the equivalent dose limit for the lens of the eye is 150 mSv in a year and that for the skin, hands and feet is 500mSv in a year. 

For comparison, the principal effective dose limit for members of the public is 1 mSv in a year. However, it is permissible to use a subsidiary dose limit of 5 mSv in a year for some years, provided that the average annual effective dose over 5 years does not exceed 1 mSv per year. The equivalent dose limits for the skin and lens of the eye are 50mSv and 15 mSv per year respectively. 

In the application of the dose limits for both workers and the public, no account should be taken of the exposures received by patients undergoing radiological examination or treatment and those received from normal levels of natural radiation. Guidance on the implementation of the ICRP principles to the protection of workers is given in reference 9. 

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