Intended for healthcare professionals

Clinical Review

The risks of radiation exposure related to diagnostic imaging and how to minimise them

BMJ 2011; 342 doi: (Published 25 February 2011) Cite this as: BMJ 2011;342:d947
  1. H E Davies, consultant respiratory physician1,
  2. C G Wathen, consultant respiratory physician2,
  3. F V Gleeson, consultant radiologist34
  1. 1Department of Respiratory Medicine, University Hospital of Wales, Vale of Glamorgan CF64 2XX, UK
  2. 2Wycombe Hospital, Buckinghamshire Hospitals NHS Trust, High Wycombe, UK.
  3. 3Department of Radiology, Churchill Hospital, Oxford Radcliffe Hospital, Oxford, UK
  4. 4Oxford NIHR Biomedical Research Centre, Oxford, UK
  1. Correspondence to: HE Davies hedavies{at}
  • Accepted 2 January 2011

Summary points

  • The demand for imaging, especially computed tomography, has increased vastly over the past 20 years

  • An estimated 30% of computed tomography tests may be unnecessary

  • Ionising radiation may be associated with cancer and other non-neoplastic sequelae

  • The risks of iatrogenic radiation exposure are often overlooked and patients are seldom made aware of these risks

  • The requesting doctor must balance the risks and benefits of any high radiation dose imaging test, adhering to guideline recommendations if possible

  • Difficult cases should be discussed with a radiologist, ideally at a clinicoradiological or multidisciplinary team meeting

Since the 1970s, when computed tomography was introduced into clinical practice, the array of imaging tests that expose patients to radiation has vastly increased. This is a result of improved computed tomography techniques, advances in other techniques such as digital subtraction angiography, and the development of modalities such as positron emission tomography coregistered with computed tomography and single photon emission tomography coregistered with computed tomography. Improvements in non-ionising radiation imaging techniques, such as magnetic resonance imaging with increased field strength (3T) and multichannel technology, and Doppler and colour flow applications in ultrasound, have also occurred.

Sources and selection criteria

We searched PubMed and used our personal reference collections. We also reviewed guidelines from the British Thoracic Society, Royal College of Radiology, and American College of Radiology. In addition, we retrieved national recommendations from the National Institute for Health and Clinical Excellence (NICE).

The demand for imaging has grown for several reasons. The development of picture archiving computer systems, which enable the referring doctor to view images easily, may have led to an increase in requests for diagnostic imaging. The public has become more aware of imaging tests and their potential benefit, especially in screening for cancer and cardiac disease, and faster scanners have allowed for imaging in previously unsuitable patients. Enhanced spatial …

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