Analysis of significant deviations
Significant radiation safety deviations must be reported to the Radiation and Nuclear Safety Authority (STUK) without delay. Reports must be submitted immediately regarding, for example, deviations in which the radiation safety of employees or the population has been compromised or, for example, a failed radiological examination has caused significant radiation exposure to a patient. Since 2010, STUK has received nearly 1,200 reports, most regarding health care. The majority of radiation safety deviations reports subject to immediate reporting by health care units concerned additional radiation exposures caused to patients.
Immediately submitted reports on significant radiation safety deviations include detailed information on the course of the event, the persons exposed and the corrective measures taken to prevent similar events. In the processing of a radiation safety deviation, the Radiation and Nuclear Safety Authority (STUK) ensures that the measures taken by the health care unit are sufficient for it to learn from the event and to improve its operations.
The number of reports on radiation safety deviations requiring immediate reporting has varied over time. This number is affected by factors such as the criteria in force for submitting a report and how well radiation operators know about their obligation to submit reports. From the beginning of 2010 to December 2024, health care units submitted 746 reports subject to immediate reporting to the Radiation and Nuclear Safety Authority. This summary focuses on radiation safety deviations in 2019–2024, with the exception of Figure 1.
Figure 1. Radiation safety deviations requiring immediate reporting in health care.
The Radiation Act was reformed at the end of 2018 and a connected new regulation on radiation safety deviations was issued along it. In connection with the reform, the criteria for which deviations shall be reported immediately were also updated. The change in the number of reports in 2018–2019 is mainly due to the changes in reporting criteria.
During the current Radiation Act, the majority of radiation safety deviations reported by health care operators concern significant unplanned medical exposure or additional radiation exposure caused to employees.
Figure 2. Radiation safety deviations requiring immediate reporting in health care by type in 2019-2024.
The regulation on radiation safety deviations specifies what kind of deviations are significant unplanned medical exposure. The term significant unplanned medical exposure includes a wide range of radiation safety deviations affecting patients, support persons and foetuses.
A radiation safety deviation from a significant unplanned medical exposure, as defined in the regulation, does not directly mean that the incident has caused significant harm to the exposed patient, support person or foetus. This term defines the events that must be notified to the Radiation and Nuclear Safety Authority without delay so that it can take the necessary action in the control of radiation activities.
The majority of the reports concerned failed examinations or procedures that caused an additional exposure to the patient of more than 10 millisieverts (mSv). A typical event is, for example, a CT examination, which has had to be repeated after a failed contrast agent injection. Failed examinations and procedures that resulted in an additional exposure of less than 10 mSv to the patient were subject to summarized reporting once a year.
Figure 3. Reports of radiation safety deviations from significant unplanned medical exposure classified into different types of events in 2019-2024.
Based on reports submitted to the Radiation and Nuclear Safety Authority, it is very rare for radiation safety deviations where the resulting radiation exposure exceeds the dose limit for employees or the population or the applicable dose constraintto occur in health care units.
There were 44 radiation safety deviation reports concerning occupational exposure, and in three of these cases, the exposure of the most exposed worker was 0.1 mSv or more. There were four public exposure events and the highest exposure caused by these events was 33 microsieverts (μSv).
Figure 4. The most significant radiation exposures for workers caused by radiation safety deviations in health care. The radiation safety deviations are arranged in order of the magnitude of exposure. Note the logarithmic scale of the occupational exposure chart.