Complementary notification codes

Complementary notification codes

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


Incidents that do not necessarily meet the criteria for statutory notification but, because of other significant or unusual circumstances, may be submitted to share 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)

These are notifiable regardless of the doses received by each individual person, where either:

  • a theme has been identified over a number of incidents
  • a single incident has involved multiple individuals
  • a separate but similar incident has been identified that affects more than one individual.


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 to 9, to indicate the most relevant exposure category for the incident. More than one complementary code may be relevant.

Interventional radiology and cardiology (including interventional CT procedures)

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

The UK enforcing authorities have determined that the following must be reported:

  • all procedural failures resulting in observable deterministic effects (excluding transient erythema)
  • procedures that do not have a procedural error but result in unintended or unpredicted observable deterministic effects.

The Notification codes, categories and criteria table provides guidance on this.

You may submit a voluntary notification when there is no procedural failure if doing so will lead to wider learning. This is at the discretion of employers.

Radiotherapy treatment verification imaging

There is no change to the threshold relating to images in a single fraction (category 4.2a). However, the thresholds for notifications relating to imaging exposures over the course of treatment have changed (4.2b and 4.2c).

In this previous threshold:

“When the number of additional imaging exposures is 20% greater than intended over the course of treatment due to protocol failure or equipment error”

The threshold has increased to 50%. This is to reflect the increase in short course fractionation treatments and the relatively low dose of verification images. 

You now only need to make notifications in the following situations:

  • Set-up error leads to 3 or more imaging exposures in a single fraction (including the intended image, which is 3 images in total). 
  • When the number of additional imaging exposures is 50% greater than intended over the course of treatment as a result of protocol failure
  • When the number of additional imaging exposures is 50% greater than intended over the course of treatment as a result of thematic hardware or software failure

These thresholds apply to all radiotherapy treatment regimes, including radical short course fractionation (classed as 10 fractions or less). Examples of thematic failure could be a persistent equipment fault or repeated human factor error. However, we rely on employers to use professional judgement to identify themes.

Foetal exposure

The reporting threshold for foetal exposures has changed. Previously a procedural failure was needed to instigate reporting, but this is no longer the case. However, the dose threshold has been raised from 1 mGy to 10 mGy, in line with guidance Protection of Pregnant Patients during Diagnostic Medical Exposures to Ionising Radiation (Royal College of Radiologists)

Therefore, you must report if a foetus has an exposure over 10 mGy – even when procedures were followed.

Incorrect radiopharmaceutical administration

A new reporting category now captures all administrations of an incorrect radiopharmaceutical, regardless of the dose to the patient. This applies even when the correct isotope was given but with the wrong tracer, for example technetium-99m MAA instead of technetium-99m HDP.


Regulation 8(4)(b) requires employers to make notifications of radiotherapeutic exposures that are significantly lower than intended, as set out in the criteria in the table (codes 8.1 and 8.2). This includes:

  • nuclear medicine therapy
  • radiotherapy
  • brachytherapy
  • intraoperative therapy. 

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

Laterality errors

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