Unintended overexposure of a patient during palliative radiotherapy treatment: investigation report

Report into the unintended overexposure of a palliative radiotherapy patient in Edinburgh Cancer Centre in December 2017.

7. Summary of principal findings

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

A patient with a history of metastatic breast cancer, and left vocal cord palsy, thought to be associated with the patient's cancer diagnosis was referred by the Ear, Nose and Throat Department of NHS Lothian's University Hospitals Division to the ECC.

At the ECC oncology clinic, Clinical Oncologist B completed a standard ECC informed consent pro-forma for a suitable course of palliative radiotherapy of the 'Mediastinum' with the intent 'To shrink the hilar mass', and made arrangements for an 'ad-hoc'* treatment planning session.

The prescribed radiation dose, method of delivery, and fractionation were as expected for treatment of this condition, and in accordance with the relevant ECC Employer's Written Protocol for 'Clinical management guidelines for lung cancer'.

In this case, however, Clinical Oncologist B, defined a treatment field that did not (as per the completed informed consent pro-forma) encompass the 'hilar mass' and therefore had no possibility of achieving the hilar mass shrinkage referred to therein.

Palliative treatment was planned accordingly and was delivered between 27 December 2017 and 4 January 2018.

While no definite conclusions can be made, the most likely scenario appears to be that Clinical Oncologist B made an initial field placement as a 10cm x 10cm square that covered an area centred on the mediastinum and included the hilar mass, but then, on observing on the screen another area of possible concern immediately outside the lower right corner of this area, sought to extend this field to include this area. However, in attempting to do so, it appears that instead of extending this initial radiotherapy treatment field, Clinical Oncologist B shifted this treatment field to a different part of mediastinum that no longer covered the original intended hilar mass target

The patient was fully informed of the error and underwent subsequent radiotherapy to the area originally intended.

The magnitude of this overexposure is such that there was a significant possibility of harm to the patient. However, the ECC has reported that there have been no unusual adverse clinical outcomes associated with this error and that none are expected to occur.

Clinical Oncologist B was properly entitled to carry out all of the functions undertaken (as referrer, practitioner and operator), and in no sense did Clinical Oncologist B fail to comply with the duty-holder responsibilities specified in the IR(ME) Regulations. Neither was there clear evidence of an error in clinical judgement, in that Clinical Oncologist B believed 'at the time' that the presentation on the CT scan justified an extension of the mediastinal field to the lower right. The error appears therefore to be one of process in inadvertently shifting rather than extending the field.

The investigation also considered compliance with the duties of the employer under the IR(ME) Regulations. In this regard there is evidence of a failure by the employer to keep appropriately detailed training records and concern about the resources being deployed to maintain employer's written procedures and protocols to an appropriate standard. However, there is no evidence to suggest that these shortcomings contributed in any way to the error in field placement.

No evidence has therefore emerged to indicate need for enforcement action under the IR(ME) Regulations.


Email: Richard Dimelow

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