Radiation Protection In Veterinary Medicine - Recommended Safety Procedures For Installation And Use Of Veterinary X-ray Equipment - Safety Code 28

Appendix I - Permissible Dose Equivalent Limits of X-Radiation to Operators and Other Occupationally Exposed Personnel

For the purpose of radiation protection, individuals may be classified in one of two categories: those exposed to radiation during the course of their work (radiation workers), and others. Maximum permissible levels are given for both categories in the following table. These dose equivalent limits are based on the latest recommendations of the International Commission on Radiological Protection (ICRP) as specified in ICRP Publication 60.

Permissible dose equivalent limits for radiation workers apply only to irradiation resulting directly from their occupations and do not include irradiation from other sources such as medical diagnoses and background radiation.

Permissible Dose Equivalent Limits of X-Radiation to Operators and Other Occupationally Exposed Personnel

Annual permissible dose equivalent limits
Applicable body organ or tissue	Radiation workers	Other workers and members of the public
Whole body	20 mSv	1 mSv
Lens of the eye	150 mSv	15 mSv
Skin	500 mSv	50 mSv
Hands	500 mSv	50 mSv
All other organs	500 mSv	50 mSv

Notes:

1. Any exposure may involve some degree of risk. Although the levels recommended in this Appendix are maximum permitted values, all doses should be kept as low as reasonably achievable. Any unnecessary exposures must be avoided.
2. ICRP does not recommend discrimination in the dose limits between men and women of reproductive capacity, if the dose is received at an approximately regular rate.
3. Once an occupationally exposed woman has been declared pregnant, the fetus should be protected from external exposure by applying a dose equivalent limit of 2 mSv to the surface of the woman's abdomen for the remainder of the pregnancy, with no more than 1 mSv in the period from 8 to 15 weeks after conception.
4. For operators-in-training and students, dose equivalent limits for members of the general public should apply.
5. ICRP does not recommend different limits for individual organs. For occupationally exposed workers ICRP believes that deterministic effects will be prevented by applying a dose equivalent limit of 500 mSv in a year to all tissues except the lens of the eye, for which it recommends a limit of 150 mSv in a year.
6. For the skin the dose equivalent is averaged over its whole area. In situations where deterministic effects are possible, the recommended dose equivalent limit for the skin is 500 mSv and is averaged over areas of no more than about 1 cm2. This limit applies to the skin of the face and the hands.
7. In special circumstances ICRP limits allow a higher value of effective dose that is allowed in a one-year period, as long as the average dose over a five-year period is not greater than the annual limit. This higher value is 50 mSv for occupationally exposed personnel. However, in veterinary medicine there is no circumstance in which this provision should apply.
8. Some provincial jurisdictions may have permissible dose equivalent limits for some workers that differ from those listed in Appendix I. Consultation with the proper agency may be required to determine the permissible dose equivalent limits in effect in a particular jurisdiction.