ENS 56041
ENS Event | |
|---|---|
04:00 Nov 1, 2021 | |
| Title | Gamma Knife Malfunction |
| Event Description | The following information was provided by South Carolina Department of Health & Environmental Control via email:
The South Carolina Department of Health and Environmental Control was notified on 08/10/2022, during a follow-up of a routine inspection, that a Leksell Gamma Knife Perfexion gamma stereotactic radiosurgery unit had failed to function as designed. The licensee [Prisma Health Richland Hospital] is reporting that during routine maintenance that was conducted by the manufacturer on 11/01/2021, it was discovered that a sector was dragging and not transferring smoothly. The licensee is reporting that one of the sealed sources had slipped less than 1/8 inch within one of the source cavities of the Leksell Gamma Knife Perfexion unit. The sealed source is a Co-60 Elekta Model 43685 medical teletherapy source, with an estimated activity between 20-22 curies. The licensee is reporting the unit was repaired and source reseeded on 11/05/2021. The licensee is reporting no overexposures to workers, patients, or members of the public. All sealed sources were leak tested on 11/05/2021 and results indicated that no sources were leaking. This event is under investigation by the South Carolina Department of Health and Environmental Control.
The following information was provided by South Carolina Department of Health & Environmental Control via email: The licensee has submitted a 30-day written report. The Co-60 Elekta Model 43685 medical teletherapy source serial number is NIW098 with an estimated activity of 20.6 Ci (0.7622 TBq) at the time of the event. On 11/05/2021, the manufacturer and service representative identified the bushing containing the source had slipped slightly from its sleeve. The bushing was visually inspected via remote camera and showed no damage. The bushing and source was reseeded into its sleeve on 11/05/2021. No patients were treated between 11/1/2021-11/10/2021. The licensee is reporting no overexposures or medical events. The licensee performed areas surveys (using a Fluke 451PYR, calibrated 04/08/21) on 11/03/21 and 11/05/21, records indicated dose rate readings that were consistent with the radiation levels in the sealed source and device registry for the Perfexion unit. The licensee also performed area contamination surveys/wipes (using a Capintec Captrac, calibrated 10/18/21) on 11/03/21 and 11/05/21, records indicated contamination levels below the licensee's removable contamination trigger limits. This event is still under investigation by the South Carolina Department of Health and Environmental Control. Notified R1DO (Defrancisco) and NMSS Event Notification via email.
The following update was provided by the state of South Carolina via email: The manufacturer (Elekta, Inc.) submitted a report dated 10/14/22. The manufacturer's estimate of the effect on the dose rate is a reduction of about 0.3 percent for the 4 mm collimator with one loose bushing in the worst angle. The manufacturer's estimate of the effect on the delivered dose was 1.5 mGy less than planned. The licensee reported the typical patient dose range is 32-85 Gy. The manufacturer performed a root cause analysis in the report dated 10/14/22. The manufacturer determined that when pushing the bushing into the sleeve, the bushing can be slightly misaligned with the sleeve making it stick without the spring being properly activated. Later the bushing can come loose due to vibrations. The manufacturer determined this is what is likely to have happened here. The licensee's corrective actions included determining the root cause of the event, reseating the bushing and lubricating all sectors, determining no other bushings were loose/unseated, performing acceptance testing prior to treatment of the first patient after event, and having future source loadings confirm all source bushings are properly seated prior to turning the unit over for acceptance testing. The licensee did not identify any other instances where a source/bushing slippage had occurred. This event/investigation is closed. Notified R1DO (Carfang) and NMSS Events Notification email group. |
| Where | |
|---|---|
| Prisma Health Richland Hospital Columbia, South Carolina (NRC Region 1) | |
| License number: | 586 |
| Organization: | Sc Dept Of Health & Env Control |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+6797.25 h283.219 days <br />40.46 weeks <br />9.311 months <br />) | |
| Opened: | Adam Gause 09:15 Aug 11, 2022 |
| NRC Officer: | Karen Cotton-Gross |
| Last Updated: | Nov 22, 2022 |
| 56041 - NRC Website | |
Prisma Health Richland Hospital with Agreement State | |
WEEKMONTHYEARENS 560412021-11-01T04:00:0001 November 2021 04:00:00
[Table view]Agreement State Gamma Knife Malfunction 2021-11-01T04:00:00 | |