Failure Modes and Effects Analysis (FMEA): Based Quality Management Program for Stereotactic Radiosurgery

Abstract

Stereotactic radiosurgery is a highly precise and accurate treatment technique for treating brain diseases with low serious error risks that nevertheless could potentially be reduced. We applied the AAPM Task Group 100 recommended failure modes and effects analysis (FMEA) tool to develop a risk-based quality management program for Gamma Knife radiosurgery. A team consisting of medical physicists, radiation oncologists, neurosurgeons, radiation safety officers, nurses, operating room technologists, and schedulers at our institution and an external physicist expert was formed for the FMEA study. A process tree and a failure mode table were created for the Gamma Knife radiosurgery procedures using the Leksell Gamma Knife Perfexion and 4C units. Three scores for the probability of occurrence, the severity, and the probability of no detection for failure modes were assigned to each failure mode by each professional on a scale from 1 to 10. Members of the team only contributed to the scoring for the steps with which they were familiar. The risk priority number (RPN) for each failure mode was then calculated as the average scores from all data sets collected. The established process tree for Gamma Knife radiosurgery consists of 10 sub-processes and 53 steps, including a sub-process for frame placement and 11 steps that are directly related to the frame-based nature of the Gamma Knife radiosurgery. Out of the 86 failure modes identified, 40 failure modes are Gamma Knife-specific, caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the Gamma Knife helmets and plugs, the skull definition tools as well as other features of the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all external beam radiation therapy techniques. The failure modes with the highest hazard scores are related to imperfect frame adaptor attachment, bad fiducial box assembly, overlooked target areas, inaccurate previous treatment information, and excessive patient movement during MRI scan. The implementation of the FMEA approach for Gamma Knife radiosurgery enabled deeper understanding of the overall process among all professionals involved in the care of the patient and helped identify potential weaknesses in the overall process. Some process steps were redesigned and controls put in place to address the identified potential weaknesses. A review of the impact of the redesign and controls on the process outcome will be performed in six months.