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SAUE: Criteria for making a notification

  • Organisations we regulate

The table shows the criteria for a significant accidental or unintended exposure (SAUE) that must be notified to the appropriate enforcing authority.

We use the ‘effective dose’ as the principal dose parameter, including for radiotherapy planning and verification imaging. However, where it is difficult to assess the effective dose or where alternative dose units are more relevant, the notification form allows you to add this information in the relevant section.

In England only, there are age-related dose thresholds for notifications of accidental and unintended exposures.

Interventional radiology and cardiology (including interventional CT procedures)

Determining the extent of any ‘unintended’ dose across a range of examinations and treatments in interventional radiology and cardiology is complex.

Where there is a local diagnostic reference level (DRL), enforcing authorities have determined that a dose greater than or equal to 10 times the local DRL will help you to determine what incidents are notifiable. This applies even when there has been no procedural failure.

Where local DRLs are not available, you should refer to national or European DRLs and/or review historical doses delivered for the same or similar procedures.

We also include deterministic effects (excluding transient erythema) in the criteria for making notifications of interventional radiology and cardiology exposures.

You can also submit a notification if it will lead to wider learning. This is at the discretion of the employer.


The previous notification threshold of 2.5 times the intended dose is amended to:

  • Pre-treatment planning scans: you only need to make a notification when a scan needs to be repeated twice to obtain an appropriate data set. This means that three scans in total would be notifiable, including the intended exposure.
  • Treatment verification images: you now only need to make notifications when:
    • due to set up error or equipment malfunction, three or more images are taken in one fraction to obtain an appropriate data set OR
    • if the number of additional imaging exposures is 20% greater than intended (according to a provider’s own protocols) over the course of treatment.

There is no change to the thresholds for reporting under and overdosing of delivered therapeutic dose.

Nuclear medicine therapy

Therapeutic nuclear medicine is now categorised separately from external beam radiotherapy and brachytherapy (notification codes 9.1 and 9.2).

For most nuclear medicine therapies, the existing notification threshold is still +/-10%. However, there is now a separate category for Selective Internal Radiation Therapy (SIRT) procedures.

This is because of the more complex delivery method and complications that can arise during these procedures.

For SIRT procedures, you should now report incidents to the relevant authority when the delivered activity falls outside +/- 20% of the prescribed activity.

As well as all notifiable therapy incidents, departments can consider making a voluntary notification for non-notifiable and near-miss incidents, due to the high-risk nature of these procedures and the opportunity for shared learning around incident themes. All clinically significant incidents must be reported to the relevant authority. There are examples in the latest guidance from professional bodies on IR(ME)R: Implications in clinical practice in radiotherapy: Guidance from the Radiotherapy Board.

Laterality errors

If an incident involves an exposure to the incorrect laterality, for example left shoulder instead of right, it is categorised as an unintended exposure. In this case, you should apply the multiplication or threshold values shown in the ‘Criteria for notification’ column.


Regulation 8(4)(b) requires employers to make notifications of radiotherapeutic exposures that are significantly lower than intended. This includes nuclear medicine therapy, radiotherapy, brachytherapy and intraoperative therapy.

You do not need to make a notification of exposures lower than intended for non-radiotherapeutic modalities.

Complementary notification codes

As well as notification codes 1-9, the table includes complementary codes that help to identify specific types of incident:

  • Voluntary: incidents that do not necessarily meet the criteria for statutory notification but, because of other significant or unusual circumstances, may be submitted for wider learning. These may include near misses, such as wrong treatment plans in radiotherapy or brachytherapy that are identified before delivering an exposure, or where a wrong treatment plan is used but the outcome was not clinically significant.
  • Clinically significant: incidents involving ‘clinically significant’ exposure(s). The criteria for these are developed and published by professional bodies.
  • Multiple individuals (more than one): where a theme has been identified over a number of incidents, where a single incident has involved multiple individuals, or where a separate but similar incident has been identified that affects more than one individual. These are notifiable regardless of the doses received by each individual person.
  • Equipment: refers to incidents where equipment failures are the direct cause.

Where a notification specifies a complementary notification code as the basis for an incident, you must also provide a notification code 1-9, to indicate the most relevant exposure category for the incident. More than one complementary code may be relevant.

Incidents that do not meet the SAUE notification criteria

You do not need to make a statutory notification for:

Incidents involving medical and non-medical ionising radiation that do not meet the dose threshold and notification criteria for SAUE, including near misses, still need to be investigated and analysed locally under Regulation 8(3). Employers must record the analyses of these events, which should consider any thematic reviews and trend analyses.

Examples could include wrong patient exposures, wrong radiopharmaceutical, or wrong radiotherapy treatment plan – even where there is no harm to the patient.

You should also consider coding all incidents to understand total numbers of similar incidents irrespective of whether they are notified or below the relevant notification threshold. The appropriate enforcing authority will review these analyses through regulatory monitoring activity and will collect data from employers periodically. This type of evidence, together with SAUE notifications and knowledge of local governance processes for managing radiation incidents, may be used to assess compliance with Regulation 8 more generally and may be requested as part of an IR(ME)R inspection.

This guidance will be reviewed periodically and revised as necessary, based on analyses of notifications received by enforcing authorities. This is to ensure consistent notification practice among employers and to share wider learning of SAUE incidents.

Last updated:
24 August 2020