The following was received from the Rhode Island Department of Health (RIDOH; the Department) via email:
On March 4, 2020, the Department's staff at RIDOH, Radiation Control Program became aware of a medical event (ME) that occurred at the Rhode Island Hospital, Department of Radiation Oncology in Providence on March 3, 2020. The ME is reportable as per 10 CFR 35.3045(a)(1)(i)(A) and meets the criteria for an Abnormal Occurrence.
On March 3, 2020, a patient underwent Gamma Knife treatment of a left vestibular schwannoma. At the conclusion of the treatment it was discovered that the location of the anterior screws securing the patient's head in the treatment position had moved. Before the patient was moved from the treatment table, the patient's position was observed by the radiation oncologist, neurosurgeon, and medical physicist. It is unknown at this time what contributed to the event and how the screws securing the patient in the treatment position had shifted from the initial position. Based on information provided by the patient and other participants associated with this event, a delivered dose was estimated using the GammaPlan Treatment Planning System. The estimated delivery to the target coverage area (volume of tissue receiving dose) was 44 percent. The estimated dose to the target was 4 Gy (400 rad). An unintended dose to a region of the left temporal lobe within the brain was estimated to be 13.6 Gy (1,360 rad). On the day of the incident, the attending neurosurgeon spoke directly with the patient informing the patient that the stereotactic frame had disengaged from his head at some point midway through the treatment and resulted in an unclear radiation dose to the tumor. The patient was informed of the estimated dose and told of the licensee's plan to obtain a follow-up brain MRI within 1-2 weeks after treatment and approximately 3 months after treatment.
The licensee is taking a number of corrective actions, including having the radiation therapist ensure that the patient understands that any movement of their head within the headframe is not anticipated and should be communicated immediately.
Event Report ID No: RI2020-01
A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.