Quarterly assessment of radiotherapy events, classified as level 1 on the ASN-SFRO scale, reported to the ASN between October 1 and December 31, 2009

Between October 1 and December 31, 2009, 15 radiotherapy events were classified as level 1 on the ASN-SFRO scale^[1]. These events, not expected to have any impact on patients’ health, are nonetheless analysed so as to determine the consequences thereof (particularly in terms of organisation) and to prevent them from recurring.

 Each event concerned only a single patient.

 Six events involved an irregularity in the patient's positioning due to:

•  failure to allow for an interval during the second phase of treatment, over 7 sessions;

• failure to change site during the same session, for a patient requiring treatment of two sites, resulting in the first site being irradiated with the beams intended for the second site;

• a shift in the treatment isocentre for two patients;

• a prescription error for the side requiring treatment;

• confusion between the reference points for the first treatment phase and those for the second phase, for a patient undergoing two successive treatment phases.

The last five events concerned a single radiotherapy session.

 Two events involved a beam shaping error due to:

• a collimator rotation error during 11 sessions;

• collimator slide position not adjusted to the target volume during one session.

Seven events resulted in the delivery of an inappropriate dose due to:

• - the omission of a bolus (tissue-equivalent material placed on the patient’s skin so as to alter dose distribution) during 3 sessions;

• non-compliance with the time-scale during a treatment course which stipulated 15 days between two phases;

• an incorrect distance between the radiation source and the patient. This error occurred for two different patients over 3 sessions in one case and one session in the other case;

• the first beam of treatment being performed instead of the portal image to check patient position;

• two errors concerning the identity of patients requiring treatment of the same site; these events occurred in two different facilities.

 The last three events concerned a single radiotherapy session.

[1] The purpose of the ASN-SFRO scale is to inform the general public about radiation protection events affecting patients undergoing a radiotherapy procedure. It was drawn up by the ASN in July 2007 in partnership with the Société Française de Radiothérapie Oncologique (SFRO) and was tested over a 12-month period. Further to a joint evaluation with the SFRO and the Société française de physique médicale (SFPM), the final version of the scale was published on the ASN website in July 2008.

Level 1 events are analysed during either specific inspections, or inspections conducted regularly by the ASN in all radiotherapy centres. The ASN routinely examines the corrective measures suggested after the event has been analysed by the centre, and endeavours to inform all radiotherapy centres of the conclusions of this analysis.

The corrective measures for the period involved namely consisted in intensifying checks relating to patient identity and changing organisational aspects such that operatives with limited experience are no longer left alone at the treatment station.