ARCHIVE: e-Digest Statistics about: Radioactivity

Artificial Sources of Radiation

Medical

The average annual dose from medical exposure is estimated to be 0.37 mSv, but there is considerable variation from person to person ranging from no exposure to many tens of millisieverts. There are two main sources of radiation exposure from diagnostic medical procedures. The first, and by far the largest, comes from diagnostic X-ray examinations; these include conventional chest and limb X-rays, a minor contribution from dental X-rays and the growing use of CT (computed tomography) techniques. Recent surveys indicate that although CT comprises some 4 per cent of all diagnostic procedures, it may account for more than 40 per cent of the collective dose from all procedures.

The second source of exposure from diagnostic medical procedures is from nuclear medicine, where patients are administered with radionuclides for various tests. Individual effective doses are typically a few millisieverts, and with about half a million nuclear medicine procedures a year, they contribute about 0.02 mSv to the average annual dose from medical exposure.

The NRPB advises on protection against unnecessary exposure to medical radiation based on a programme of patient monitoring in diagnostic radiology and collaboration with professional advisors and regulatory organisations. Thousands of measurements made in hospitals around the country indicate a general lowering of doses to patients for common radiography examinations during the past decade.

Annually, about 140,000 patients, mainly in the older age group, receive radiotherapy for the treatment of cancer. The absorbed dose in the target tissue is large, as the intention is to destroy or control the cancer. An estimate of the effective dose from these procedures would be extremely uncertain and inappropriate. Consequently, radiotherapy is excluded from the average annual dose from medical exposure.

Further Information:
Key Facts:
Sources
Artificial sources
Occupational radiation
Medical
Fallout
Products
Direct shine
Discharges
References, further reading and links to other resources:
[1] Hughes, J S, National Radiological Protection Board (1999). Ionising Radiation Exposure of the UK Population: 1999 Review, NRPB-R311. TSO.
[22] Hart, D National Radiological Protection Board (2002) Radiation Exposure Of The UK Population from Medical and Dental X-Ray Examinations NRPB-W4
[23] Hart, D National Radiological Protection Board (2002) Doses to Patients from Medical X-Ray Examinations in the UK: 2000 review NRPB-W14
Internet Links:
Committee on Medical Aspects of Radiation in the Environment
International Commission on Radiological Protection
National Radiological Protection Board (NRPB)

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Page last modified: 16 September 2003
Page published: 10 September 2003