The two main pieces of legislation are:

  • IR(ME)R 2017: deals with exposure to patients for medical and non-medical procedures (also IR(ME)R 2018(NI) and IR(ME)R (amendment) 2018)
  • IRR 17: deals with exposure to employees and the public

For Nuclear Imaging, there is specialised legislation:

  • MARS 78: deals with administration of radioactive substances. Governs individuals.
  • RSA 93: deals with storage and disposal of radioactive substances. Governs institutions.
  • RM(RT)R 2001: deals with transport of radioactive substances

The Ionising Radiation (Medical Exposure) Regulations (2017) (IRMER 2017)

Resource: IR(ME)R 2017

Governs all medical and, since 2017, non-medical exposures to patients.

  • Justification
  • Optimisation
  • Clinical audit
  • Training
  • Research exposure
  • Medico-legal exposure
  • Accidental and unintended dose 'incidents'
    • Need to minimise the possibilities of incidents occurring
    • Includes cases of operator or procedural failure. Does not include unintended doses due to equipment failure as these are covered by the IRR99

A new requirement in the updates is that patients must be informed of the benefits and risks prior to the exposure taking place. Also, comforters and carers must be exposed knowingly and willingly indicating they, too, must be consented and made fully aware of the potential risks of radiation exposure.

**** The main mantra of IRMER is ALARP: ****

As Low As Reasonably Practical

Diagnostic Reference Levels (DRLs)

Resource: National Diagnostic Reference Levels 15 November 2018 onwards

Gives guideline of doses, not legal limit (there is no limit for patients but doses should be as low as possible). These may vary from centre-to-centre and patient-to-patient but should not vary significantly from the nationally agreed values.


Radiograph ESD (mGy) DAP (Gy cm2)
Abdomen AP 4 2.5
Chest AP 0.2 0.15
Chest PA 0.15 0.1
Cervical spine (AP and lat)   0.3
Knee (AP and lat) 0.6 0.6
Lumbar spine AP 5.7 1.5
Lumbar spine lat 10 2.5
Pelvis AP 4 2.2
Shoulder AP 0.5  
Skull AP/PA 1.8  
Skull lat 1.1  
Thoracic spine AP 3.5 1.0
Thoracic spine lat 7 1.5


Adult CT DLP (mGy cm)
Head 970
Cervical spine 440
Chest 610
CTPA 440
Abdomen 910
Abdomen and pelvis 745
KUB - non-contrast 460
Chest, abdo and pelvis >1000
Paediatric CT DLP (mGy cm)
Paeds head: 0-1 y 350
Paeds head: >1-5 y 650
Paeds head: <5 y 860
Adult CT-PET / CT-SPECT DLP (mGy cm)
PET half body 400
SPECT bone scan 150
SPECT parathryoid 170
SPECT mIBG / octreotide 240
SPECT cardiac 36

Roles and responsibilities


  • Health care profession entitled in accordance with employer's and local procedures to request and refer individuals for medical exposure
  • Required to supply practitioner with sufficient medical information


  • Required to justify all medical exposures e.g. person who vets requests
  • Can be the radiologist or radiographer


  • Carries out and optimises the medical exposure
  • Includes radiographer pressing the exposure button and technician performing annual quality assurance tests
  • May have responsibility for authorising exposures under written guidance from a practitioner e.g. radiographers in walk-in chest x-ray lists can justify AND carry out procedure, i.e. practitioner and operator
  • Responsible for optimisation (ALARP)


  • Implements IRMER and allocates individuals to roles
  • Provide written procedures and protocols
  • Ensure staff are appropriately trained
  • Respond where an incident has occurred

Medical Physics Expert

  • Requires national recognition certificate
  • Involved in:
    • Patient dosimetry
    • Equipment management
    • Optimisation
    • Advice on regulatory compliance


  • Referrer doesn't need to justify procedure
  • Practioner justifies exposure
  • Operator optimises exposure, ensures ALARP followed, and operates image intensifier in fluoroscopy (may also be practitioner)


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Ionising Radiation Regulations 2017 (IRR17)

Resource: IRR17

Made under the Health and Safety at Work Act 1974 and designed to minimise radiation exposure to employees and members of the public. They are enforced by the Health and Safety Executive (HSE)

  • Designed to ensure exposure to workers and members of the public follows ALARP
  • Final responsibility for radiation safety lies first and foremost with the employer

Roles and Responsibilities

Radiation protection advisor

  • Usually an expert physicist and should be trained in the use of radiation and have thorough knowledge of the associated hazards and their control
  • Must have a certificate of competence issued by a body recognised by the HSE
  • Doesn't have any responsibility for radiation safety
  • Advises on:
    • Identification and designation of controlled and supervised areas
    • Calibration of monitoring equipment
    • Risk assessments
    • Drawing up of local rules and contingency plans
    • Quality assurance programmes

Radiation protection supervisor

  • Appointed by employer
  • Ensures local rules are being complied with
  • Must know what to do in an emergency
  • Must always be present on site


  • Not knowingly expose themselves or others to ionising radiation to a degree that is greater than necessary
  • Make full and proper use of Personal Protective Equipment and report any defects in it
  • Inform the employer about suspected incidents

Prior risk assessment

This is mandatory before starting a new activity involving ionising radiation

  • Identify hazards
  • Decide who may be harmed and how
  • Evaluate the risks and decide on precautions
  • Record your findings and implement them
  • Review your assessment and update if necessary

Dose limits per calender year

To limit stochastic effects the effective dose limits are:

Employees and trainees 18 years old or more

20 mSv or

100 mSv in any period of five consecutive calendar years subject to maximum equivalent dose of 50 mSv in any single calendar year

Trainees < 18 years old

6 mSv

(i.e. < 3/10 of adult dose)

Anyone < 16 years old or any person other than employee or trainee

1 mSv

Dose limit to abdomen of person of reproductive capacity 13 mSv in any consecutive 3 months
Any person (not carer or comforter) that may be exposed to ionising radiation resulting from medical exposure of another person 5 mSv in any period of 5 consecutive calendar years
Dose to fetus of pregnant employees 1 mSv for remainder of pregnancy


To prevent deterministic effects the equivalent dose limits in a calendar year are:

Area Employees and trainees 18 years old or more Trainees under 18 years old Any person (not carer or comforter) who may be exposed resulting from medical exposure of another person
Lens of the eye 20 mSv in a calendar year averaged over 5 years with no single year exceeding 50 mSv 15 mSv 15 mSv
Extremities 500 mSv 150 mSv 50 mSv
Skin 500 mSv 150 mSv 50 mSv

Classified workers

This is anyone who is likely to receive:

  • Effective dose of > 6 mSv in a year (3/10 of dose limit)
  • Equivalent dose of greater than 3/10 of any dose limit i.e.
    • > 15 mSv/yr to lens
    • > 150 mSv/yr to skin or extremities

Classified workers must:

  • Must have a medical examination before being designated
  • Must have periodic review of health at least once a year
  • Must be at least 18 years old
  • Records of doses received by classified workers must be kept until the person has, or would have, reached 75 years old and at least 30 years from when the record was made

Designation of special areas

Controlled areas

  • Any person working in the area is likely to receive an effective dose of > 6 mSv or equivalent dose of > 3/10 of any relevant dose limit
  • Any person who enters or works in area must follow special procedures to restrict significant exposure

Supervised area

  • Required if anyone working in the area is likely to receive a dose > 1 mSv/yr or an equivalent dose of > 1/10 of any relevant dose limit (i.e. more than the dose limits for the general public)

Reporting overexposure

When caused by equipment failure the following overexposures must be reported to the Health Safety Executive (HSE):

Investigation Intended dose multiplying factor
Fluoroscopic procedure with contrast agents
CT scans
Interventional procedures
1.5 x
10 x
Skull, dental and extremity x-rays
20 x

Nuclear medicine department

Medicine (Administration of Radioactive Substances) Regulations 1978 (MARS78)

  • Regulates administration of a radioactive substance
  • Do not apply to substances that are naturally radioactive or administered for properties other than their radioactivity
  • ARSAC certificates are granted to medical practitioners directly involved in nuclear medicine and identify all procedures that the individual is able to carry out. The ARSAC certificate holder can assign suitably trained people to actually administer the radioactive substances
  • Certificates are valid for 5 years

Radioactive Substances Act 1993 (RSA93)

  • Governs storage and safe disposal of radioactive materials
  • Imposes requirements for traceability and record keeping and contamination monitoring
  • Regulated by the Environment Agency
  • Registration certificates are awarded to the sites of work, not individuals

Radioactive Material (Road Transport) (Great Britain) Regulation 2001

  • Govern the transport of radioactive substances by road

Next page: Radiation protection

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