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Executive Summary
Introduction
1. Between 5th January 2006 and 31st January 2006, patient Lisa Norris, who was then 15 years old, received a dose of ionising radiation much greater than that intended while undergoing a course of radiotherapy at the Beatson Oncology Centre ( BOC) in Glasgow. The incident has been investigated by the Inspector warranted by the Scottish Ministers as regulators for Statutory Instrument 2000 No. 1059, The Ionising Radiation (Medical Exposures) Regulations 2000 (the IR(ME) Regulations).
2. The Inspector's report records the findings of the incident investigation. It identifies the error that caused this overexposure and includes consideration of the deficiencies that contributed to the error and where responsibilities for these deficiencies lay. It also makes recommendations intended to minimize the possibility of recurrence of any similar error and to enhance patient safety in radiotherapy more generally.
Background
3. When a patient is referred for radiotherapy, a clinical oncologist determines the method of treatment and the total radiation dose. To optimize the safety and effectiveness of this treatment, this total dose is usually delivered in fractions, normally one per day, and careful, detailed planning is needed to ensure that each fractional dose of radiation is properly targeted.
4. Treatment plans vary in complexity, the more complex relying on computer treatment planning systems designed for this purpose. The computer treatment planning system used by treatment planning staff at the BOC is a module called Eclipse (registered trade mark). which is a major component of a comprehensive computer system called Varis (registered trade mark). The output from Eclipse is a Treatment Plan Report that includes treatment delivery parameters.
5. In May of 2005 the Varis system at the BOC was upgraded to Varis 7. This change allowed the treatment delivery parameters in the Eclipse Treatment Plan Report to be transferred electronically to another software module within the Varis system. Previously, this transfer was by manual transcription of data to paper forms. However, for some of the most complex treatment plans, including the 'whole CNS' (central nervous system) plan which is the subject of this report, the use of paper forms was retained at the BOC.
The nature and consequences of the error
6. Changing to the new Varis 7 system introduced a specific feature that, if selected by the treatment planner, changed the nature of the data in the Eclipse Treatment Plan Report relative to that in similar reports prior to the May 2005 upgrade. This feature was selected but the critical error was that the treatment planner who transcribed the resulting data from the Treatment Plan Report to the paper form (the planning form) was unaware of this difference and therefore failed to take the action necessary to accommodate the changed data. Further details relating to this feature and the related error are in sub-section 4.2.3 of the report.
7. The outcome was that the figure entered on the planning form for one of the critical treatment delivery parameters was significantly higher than the figure that should have been used.
8. This parameter, the 'Monitor Units' is a number that relates directly to the dose of radiation to be delivered and is set on the console of the treatment unit (the linear accelerator of 'Linac'). This setting is, in turn, transmitted automatically to a monitor within the Linac which measures the amount of radiation delivered to the patient. This monitor then ensures that treatment stops when the prescribed dose of radiation has been received.
9. The error was not identified in the checking process for the treatment plan and the planning form with the erroneous entry was passed to the radiographer who managed treatment delivery.
10. The Monitor Unit setting used for each of the first 19 daily treatments was therefore too high and the cumulative radiation dose received by Miss Norris in these 19 fractions was some 58% higher than the total that was prescribed for the whole of this course of treatment.
11. The error came to light because the same treatment planner made the same error in the next allotted plan of this type for a different patient. On this occasion, however, the error was discovered by a treatment planning colleague and an immediate internal investigation was initiated which subsequently demonstrated the error for Miss Norris. By this time she had received 19 treatment fractions. The investigation confirmed, however, that no other patient at the BOC had been affected.
12. It is important to note that the error described above was procedural and was not associated in any way with faults or deficiencies in the Varis 7 computer system.
13. Upon discovery, the overexposure was reported promptly by the BOC to the Inspector warranted by the Scottish Ministers for the IR(ME) Regulations. Initial verbal reporting was followed by a written incident report.
14. Because of this overdose, the second phase of the prescribed treatment for Miss Norris that was scheduled to follow the whole CNS procedure, involving targeted irradiation of the tumour region, was abandoned on the instruction of the clinical oncologist.
The circumstances of the error
15. Treatment planning for Miss Norris was carried out by a treatment planner (referred to in this report as 'Planner B') of limited experience under the supervision of an experienced colleague ('Principal Planner A'). In consideration of the circumstances under which the error was made and was carried through undetected to treatment delivery, the report identifies and describes deficiencies in a number of areas including the following:
i. There were deficiencies in the BOC's compliance with the IR(ME) Regulations.
- Training records were out of date.
- Written procedures including working instructions for whole CNS planning were out of date and did not reflect current practice.
ii. There was evidence of a general inadequacy of staffing provisions for the proper establishment and maintenance of a suitable system of quality management for radiotherapy treatment planning at the BOC.
iii. There was a failure to ensure that the appropriate level of training and experience was brought to bear on planning the treatment for Miss Norris.
- The training records for Planner B have no indication of formal competence for planning this particular, complex procedure.
- Planner B had limited experience of 'whole CNS' planning and was not aware that changes associated with the upgrading of the computer system to Varis 7 had introduced a need for a critical change in the way that treatment delivery data was transferred to the relevant planning form.
- The supervision provided to Planner B in compiling this treatment plan was insufficient.
- Checking of the treatment plan was not independent of supervision.
iv. The needs for changes to working practices and procedures and for additional training to address any potential implications for patient safety of the change in computer systems in May 2005 were not properly assessed.
v. The potential improvements to patient safety following the introduction of new technologies were not properly assessed or implemented.
vi. There was a lack of written statements and of common understanding about individual responsibilities.
vii. The lessons and recommendations from previous incidents at other radiotherapy centres had not been addressed.
Responsibilities
16. The report concludes that most of the responsibility and hence any blame that can be attributed to treatment planning staff at the BOC falls to the staff member referred to in the report as Principal Planner A. This conclusion is in consideration of Principal Planner A's roles in both supervising and checking the plan in question and in allocating planning duties to an inexperienced colleague and of wider involvement in the management of the BOC's treatment planning provisions. However, the report also concludes that the actual level of attributable blame requires due consideration of the background circumstances at the BOC that contributed to risk of occurrence for this incident, including general deficiencies in the BOC's quality management systems and deficiencies in staffing resources.
Actions and recommendations
17. The BOC, both as an immediate consequence of the incident and in response to the recommendations made in the subsequent internal incident investigation, has introduced a number of procedural changes aimed at minimizing the possibility of recurrence of any similar occurrences. These are summarized in the report.
18. Additional recommendations for further actions required at the BOC include, in summary:
- A review of the responsibilities of those staff at the BOC with duties related to the IR(ME) Regulations.
- A review of the adequacy of staffing provisions for treatment planning at the BOC.
- Consideration of the need for treatment planning requests to be submitted on a timescale that allows proper distribution of work among treatment planning staff.
- Changes to the treatment planning and delivery systems must be subject to a formal review of possible safety implications by suitably qualified staff.
- Introduction of a written procedure giving clear instruction on the level and nature of supervision required for trainees undertaking planning duties.
- Introduction of procedures to ensure that quality assurance programmes are followed.
19. Recommendations for actions by other parties include:
- A review of treatment planning provisions with regard to regulatory compliance, staffing and quality system working at all five Scottish radiotherapy centres with findings reported to the Scottish Cancer Group.
- Consideration of what measures, in addition to those already identified, are required to safeguard and improve patient safety in the face of predicted increases in the level of demand for cancer radiotherapy and treatment planning in Scotland.
- Consideration of the need to further extend the guidelines currently in preparation by the National Institute for Health and Clinical Excellence ( NICE) relating to radiotherapy planning.
- Consideration of how information on incidents involving accidental or inadvertent radiation exposures in medical practice can best be shared among radiotherapy centres in the UK.
20. An Improvement Notice has been served on the BOC giving statutory force to those of the recommendations contained in this report that relate to compliance with the IR(ME) Regulations. Compliance with these requirements will be subject to subsequent inspection.
Acknowledgements
21. The report acknowledges the assistance of staff from the Health Protection Agency, the Health and Safety Executive and the Scottish Executive Health Department in conducting this investigation. It also acknowledges the cooperation of staff at the BOC in responding to questions asked and in providing documents requested during the investigation.
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