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.

Executive Summary

Summary of the incident.

A CT scan carried out on 28th November 2017 for a patient with a history of metastatic breast cancer and related left vocal cord palsy, showed an increase in size of the largest left hilar lymph node when compared with previous scans. The patient was therefore referred to the relevant Edinburgh Cancer Centre (ECC) oncology clinic.

At the oncology clinic, the patient was seen by Clinical Oncologist B, who completed a standard ECC informed consent pro-forma for treatment of the 'Mediastinum'. The aim of this treatment was 'To shrink the hilar mass', thought to be causing the left vocal cord palsy by affecting the left recurrent laryngeal nerve.

Between 27th December 2017 and 4th January 2018 the patient was given a palliative radiotherapy treatment at the ECC. The prescribed radiation dose, method of delivery, and fractionation were as expected for treatment of this condition.

Following completion of this treatment, a CT scan in March of 2018 showed, unexpectedly, that the target tumour had actually increased in volume. A second clinical oncologist, Clinical Oncologist A, therefore arranged for reassessment of the patient's imaging and treatment planning.

The outcome of this reassessment was the discovery that as part of treatment planning for this patient, Clinical Oncologist B had 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.

While no definite conclusions can be made, the most likely scenario appears to be that Clinical Oncologist B made an initial treatment field placement as a square that covered an area of the mediastinum that included the hilar mass, but then, on observing on the computer screen another area of possible concern immediately outside the lower right corner of this area, sought to extend this square to include this area. However, in attempting to do so, it appears that Clinical Oncologist B shifted rather than extended 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 ECC has reported that there have been no adverse clinical outcomes associated with this error and that none are expected to occur.

The conclusion of this investigation is that Clinical Oncologist B was appropriately 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. It appears, therefore, that the error was one of treatment field placement, whereby Clinical Oncologist B inadvertently shifted rather than extended the treatment field on the computer screen.

Contributory factors

This incident occurred on the last working day (Friday) before the Christmas Bank Holiday when Clinical Oncologist B was the only member of the relevant team on site. The usual compliment for the team Monday to Thursday is between three and five clinical oncologists, but normally only two on a Friday.

At interview, Clinical Oncologist B accepted that lone working on that particular day when subject to abnormal pressure for urgent treatment ahead of the impending hiatus in treatment over the Christmas break had probably contributed to difficulties in focussing on the various tasks in hand.

These staffing issues are considered further in the main body of the report.

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 proper training records and to maintain employer's written procedures to an appropriate standard. However, there is no evidence to suggest that these shortcomings contributed in any way to the error in field placement.

The employer has recognized the need to address these issues.

Recommendations for further action

A number of actions have been recommended in the ECC's internal report on this incident (Section 6 of this report) and senior management within the ECC have confirmed that these have been or are being properly addressed.

Further recommendations arising from this investigation and relating to improvements in recording of staff training prior to entitlement, quality control of employer's written procedures and protocols, and to improvements in working practices are also included in this report.


The main conclusions of this report are:

  • The error was made by Clinical Oncologist B in the process of defining the radiotherapy treatment field.
  • Clinical Oncologist B was adequately trained, deemed competent and appropriately entitled by the employer for this function.
  • The patient has been properly apprised of the nature and circumstances of the error and has been given appropriate aftercare.
  • The ECC has reported that there have been no unusual adverse clinical outcomes associated with this error and that none are expected to occur.
  • Deficiencies have been identified in this report in recording of training and in document quality control by the employer. However, these did not contribute to this incident.
  • The occurrence of this incident during an ad-hoc planning clinic on the last working day before the Christmas when Clinical Oncologist B was working alone leads to the general conclusion that staffing pressures were a contributory factor in the occurrence of this incident.
  • No evidence has emerged to indicate a need for enforcement action under the IR(ME) Regulations.


Email: Richard Dimelow

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