Unintended overexposure of a patient during radiotherapy treatment at the Edinburgh Cancer Centre, in September 2015

The report of a detailed investigation of an incident involving a serious overexposure to ionising radiation for a patient undergoing radiotherapy, in September 2015.

8. Summary of principal findings

The principal findings arising from investigation of this incident are summarized in the following paragraphs.

Between 14 th and 18 th September 2015, a patient at the ECC diagnosed with multiple myeloma was given a palliative radiotherapy treatment of the vertebrae of the neck to address pain and disability being caused by a bone fragment from a collapsed 'C3' vertebra.

The prescribed total dose of ionising radiation to be delivered to the patient and the method of delivery were fully in keeping with the ECC's treatment protocol for this condition, and this treatment was correctly described by the oncologist on the patient's 'Radiotherapy Prescription Sheet'. In all senses, therefore, and with particular regard to Regulation 7(2) on the optimization of radiotherapy treatment, the duties of the practitioner under the Regulations were fully met.

On the morning of Monday 14 th September a treatment planner (Radiographer A), used the correct ECC treatment planning protocol, to carry out a manual calculation of the dose of radiation to be delivered to each side of the neck for each day of treatment, but made an error in calculation. As a result of this error, the dose calculated by this Radiographer was double what it should have been.

A second treatment planner (Radiographer B), carried out a similar manual calculation, but got the same wrong answer.

Data input to the 'Aria' electronic information management system was carried out correctly by Radiographer C, and this included the (wrong) dose from the manual calculation. The associated dose calculation programme called RadCalc then calculated the daily dose to each side of the neck independently, and determined correctly that the manually calculated dose was 100% too high.

Believing that the RadCalc calculation was in error, the Radiographers involved sought assistance from a member to the ECC's Treatment Planning Section (Physicist A).

For reasons that remain unclear, Physicist A achieved an answer from RadCalc that appeared to agree with the (erroneous) manual calculations of the number of 'monitor units' to be set on the Linac for each treatment.

As a result of these errors the Linac delivered a total of 40Gy of radiation to the treatment area in 5 fractions of 8Gy, instead of the prescribed 20Gy in 5 fractions of 4Gy.

Regarding compliance with the duties of the employer under the IR( ME) Regulations, the finding of this investigation is that the structures in place at Lothian NHS Board for implementation of the duties of the employer, and for proper oversight of implementation of these duties were robust and, with minor concerns, were being applied properly. However, concerns have emerged regarding the adequacy of training provided to the operators involved, and these are considered likely to have contributed significantly to this incident.

Regarding compliance with the duties of the operators concerned, the finding of this investigation is that all of the practical aspects of the treatment undertaken by Radiographers B, C and D and by Physicist A were in keeping with their entitlement by the employer, and were in accordance with the relevant Employer's Witten Procedures and Protocols. Concerns regarding recording of the entitlement of Radiographer A to carry out manual calculations unsupervised are discussed in Sections 6 and 7 of this report, but there is documented evidence that Radiographer A had completed the training considered by the employer to be adequate for this duty.

Section 9 of this report considers the 'concerns' mentioned in the three previous paragraphs in more detail, and the recommendations arising. Section 11 considers the need for these recommendations to be supported by formal enforcement action.


Back to top