Quarterly report on Grade-1 radiotherapy events reported to the ASN, classified using the ASN-SFRO scale – third quarter of 2009

Between 1 July and 30 September 2009, 9 events were classified as Grade 1 on the ASN-SFRO scale. These events, not expected to have health consequences for patients, are nonetheless analysed for lessons learned (particularly in terms of organisation) and to ensure they do not reoccur.

 Each event concerned only one patient.

 Five events were caused by incorrect positioning of the patient due to:

• poorly positioned reference points;
• forgetting to rotate the table for one of the six beams in the treatment;
• for a patient treated for two locations at the same time, irradiation of the first location with the beams intended for the second location;
• use of the centring plates of a different patient during a stereotactic¹ radiotherapy session;
• failure to take into account a delay anticipated at the preparation stage during 4 sessions.

 The first four events involved a single radiotherapy session.

 One event was caused by a beam shaping error due to use, during a single session, of a field that was wider than planned.

 Three events resulted in an inappropriate dosage being administered because of:

• an incorrect distance between the radiation source and the patient;
• improper consideration of the activity of the source in calculation of the brachytherapy treatment time, for two events.

 Grade-1 events are investigated by ASN either during a specific inspection or during the inspections that ASN regularly carries out at all radiotherapy centres. ASN systematically examines the corrective measures proposed after the centre's analysis of the event.

The corrective measures for the period in question included formally documenting precise procedures for beam positioning and improving checks for patient positioning and content of the treatment sheet through double checking.

Technique originally used in neurosurgery which, through very careful identification of the cerebral space, enables a very precise point of the cerebral structures to be treated.