Dose Limits Trevor Boal Radiation Protection Unit RSM-NSRW
Dose limits Dose limits apply for planned exposure situations only Dose limits are set by government or the regulatory body Dose limits are enforced by the regulatory body The exposure of workers and of the public is not to exceed the dose limit Dose limits do not apply to medical exposures
Dose limits Whole body Extremities Skin Lens of the eye Workers 18+ (annual) 20* (100 msv in 5 years) 500 500 20* (100 msv in 5 years) Public (annual) 1 50 50 15 * 50 msv in any single year
Workers
Definition of worker* Any person who works, whether full time, part time or temporarily, for an employer and who has recognized rights and duties in relation to occupational radiation protection. *GSR Part 3
Workers GSR Part 3 Para 3.78 of GSR Part 3: Employers, registrants and licensees shall ensure that workers exposed to radiation from sources within a practice that are not required by or directly related to their work have the same level of protection against such exposure as members of the public.
Workers Category 1 procedures Human imaging that: Takes place in a medical radiation facility Using medical radiological equipment Performed by radiology personnel With the image reported by a radiologist/doctor Most of work will be taking medical exposures, with only a few procedures involving non-medical human imaging
Workers operating inspection imaging devices category 2 procedures Human imaging that: Takes place in a non-medical facility (often in a public place) Using specialized inspection imaging equipment Performed by non-radiology personnel With the image viewed by a non-medical person It would be expected that operators of most inspection imaging devices would receive doses of less than 1 msv in a year.
Workers incidental exposure while carrying out their work Examples: drivers of vehicles that are exposed as vehicles undergo scanning for detection of smuggled goods, workers (not operating equipment) in centre screening persons. Such workers receive exposure incidental to their work, and should receive the same level of protection as a member of the public. Public dose limit of 1 msv per year
Public
Category 1 procedures Human imaging that: Takes place in a medical radiation facility Using medical radiological equipment Performed by radiology personnel With the image reported by a radiologist/doctor Persons undergoing such procedures may receive doses which are higher than the public dose limit (1 msv) e.g. CT scan of abdomen dose of the order of 10 msv. (EC Publication 154)
GSR Part 3 Para. 3.64 of GSR Part 3: For human imaging using radiation, performed by medical personnel using medical radiological equipment, that exposes people to radiation for employment related, legal or health insurance purposes without reference to clinical indications: (a) The government shall ensure, on the basis of consultation between relevant authorities, professional bodies and the regulatory body, that dose constraints are established for such human imaging; (b) The registrant or licensee shall ensure that the appropriate optimization requirements for medical exposure in paras 3.162 3.177 are applied, with dose constraints as required in (a) above used instead of diagnostic reference levels. Such purposes for performing human imaging using radiation include: assessment of fitness for employment (prior to employment or periodically during employment); assessment of physiological suitability for a career or a sport; assessment of athletes before a selection or transfer; determination of age for legal purposes; obtaining evidence for legal purposes; detection of drugs concealed within the body; immigration or emigration requirements; pre-insurance checks; and obtaining evidence for the purposes of a compensation claim.
Public Category 2 procedure Human imaging that: Takes place in a non-medical facility (often in a public place) Using specialized inspection imaging equipment Performed by non-radiology personnel With the image viewed by a non-medical person Inadvertent or deliberate exposure of public Public dose limit of 1 msv per year
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