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Medical radiation: uses, dose measurements and safety advice

The use of ionising radiation in medicine, including recommended dose measurements and guidance on safe radiology practice.

• From: UK Health Security Agency
• Published: 1 August 2014
• Last updated: 27 May 2025 — See all updates

Ionising radiation is used in medicine in 3 ways:

• diagnostic radiology, which uses x-ray machines to obtain images of the inside of the patient’s body
• nuclear medicine, which uses radioactive substances introduced into the patient for diagnosis or treatment
• radiotherapy, which uses many types and sources of ionising radiation to cure or relieve symptoms of cancer and other diseases

These 3 areas are covered by the Ionising Radiation (Medical Exposure) Regulations 2017, which provide a framework to protect patients.

Two guidance documents have been produced in partnership with the Royal College of Radiologists, Society and College of Radiographers, Institute of Physics and Engineering Medicine and other professional bodies. The documents are entitled: Ionising Radiation (Medical Exposure) Regulations: Implications for clinical practice in radiotherapy and Ionising Radiation (Medical Exposure) Regulations: Implications for clinical practice in diagnostic imaging, interventional radiology and diagnostic nuclear medicine. The later document also extends to research labs, universities and sports facilities where medical and non-medical exposures are undertaken.

Medical radiation: risks and safety advice

• Medical imaging: what you need to know
  • 22 September 2022
  • Guidance
• Ionising radiation from medical imaging examinations: safety advice
  • 1 August 2014
  • Guidance
• Medical radiation: patient doses
  • 4 September 2008
  • Guidance
• Medical x-rays: radiation risks by age and sex of patient
  • 1 October 2011
  • Research and analysis
• Diagnostic radiology: national diagnostic reference levels
  • 20 November 2024
  • Guidance

Incident learning in clinical imaging, MRI and nuclear medicine

• User guidance and application of the national taxonomy for incident learning in clinical imaging, MRI and nuclear medicine
  • 22 April 2024
  • Guidance
• National coding taxonomy for incident learning in clinical imaging, MRI and nuclear medicine
  • 22 April 2024
  • Guidance

Diagnostic radiology

• Computed tomography (CT): national patient dose audits
  • 23 June 2022
  • Research and analysis
• Radiographic, fluoroscopic and dental x-rays: patient dose audits
  • 1 June 2012
  • Research and analysis
• Medical and dental x-rays: frequency and collective doses in the UK
  • 1 December 2010
  • Research and analysis
• Dental cone beam computed tomography: safe usage
  • 17 September 2015
  • Research and analysis
• Diagnostic radiology: national protocol for patient dose measurements
  • 14 November 1992
  • Guidance
• Computed tomography (CT): data analysis software to assess radiation doses
  • 1 January 2014
  • Research and analysis
• Hand-held dental X-ray equipment: guidance on safe use
  • 9 February 2016
  • Guidance

Nuclear medicine

There’s a dedicated committee, Administration of Radioactive Substances Advisory Committee (ARSAC), to advise the government on nuclear medicine.

• ARSAC notes for guidance: good clinical practice in nuclear medicine
  • 31 March 2025
  • Guidance

Radiotherapy

• Radiotherapy: advancing safer radiotherapy
  • 28 May 2025
  • Guidance
• Safer radiotherapy: national patient safety radiotherapy event taxonomy
  • 27 May 2025
  • Guidance
• Safer radiotherapy: triannual error analysis and learning
  • 30 May 2025
  • Research and analysis
• Radiotherapy: good practice
  • 30 March 2021
  • Guidance
• Safer radiotherapy: biennial error analysis and learning
  • 27 May 2025
  • Research and analysis

Published 1 August 2014

Last updated 27 May 2025 + show all updates

1. 27 May 2025

   Added link to 'Radiotherapy: advancing safer radiotherapy'.

2. 22 April 2024

   Added a section on "Incident learning in clinical imaging, MRI and nuclear medicine", which includes 2 new pages.

3. 22 September 2022

   Added link to 'Medical imaging: what you need to know'.

4. 23 June 2022

   Added link to the new 'Computed tomography (CT): national patient dose audits' page.

5. 30 March 2021

   Added links to 2 Ionising Radiation (Medical Exposure) Regulations guidance documents.

6. 22 December 2016

   Added: Development of learning from radiotherapy errors.

7. 22 January 2016

   Added Medical radiation: national diagnostic reference levels (NDRLs), based on existing research.

8. 23 December 2014

   The 'Safer radiotherapy: supplementary survey analysis' has been added under 'Radiotherapy'.

9. 1 September 2014

   The 'Doses from computed tomography (CT) examinations in the UK report' has been uploaded.

10. 1 August 2014

    First published.