ENS 52914
ENS Event | |
|---|---|
05:00 Aug 18, 2017 | |
| Title | Agreement State Report - Patient Underdose |
| Event Description | The following report was received via e-mail:
The licensee's RSO reported a possible medical event for four separate patients, involving a Nucletron Model microSelectron-HDR 106.990 remote afterloading brachytherapy unit. This was noticed during review by the medical physicist. The licensee notified Elekta for confirmation of the software error. The RSO confirmed on 8/18/2017, that two (2) patients were under dosed by more than 20% and the other two (2) patients were being reviewed by the medical physicist. An Elekta Notification was sent out to all MS Radioactive Licensees on 8/17/2017, that possess a Nucletron Model microSelectron-HDR. Source: 12 Ci, Ir-192, Elekta Model 105.002 Mississippi Report: MS-170002
Update: 10/18/2017 Licensee reported four (4) medical events utilizing the tandem and ring applicator model within Elekta's Oncentra Brachy Software version 4.5.2. Licensee written report received, 8/23/2017, for the period between 11/8/2016 and 8/15/2017, stated two of the four patients treated using Nucletron Model microSelectron-HDR 106.990 remote afterloading brachytherapy unit and utilizing the tandem and ring applicator model within Oncentra's Treatment Planning software received a dose less than 20% of the prescribed dose to the treatment site (base of the uterus). All of the treated patients received greater than 50 Rem and 50 percent or more of the dose expected from the administration to unintended tissue (vaginal canal). The written directives called for a prescribed dose of 28 Gy for three patients and 27 Gy for one patient, to be delivered in four (4) separate fractions to the base of the uterus. All four (4) fractions were affected for one patient, three (3) fractions for two patients, and only one (1) fraction for one patient, which received 50 percent or more of the dose expected from the administration. Patient / Estimated Dose Delivered to Treatment Site / Percent of Intended Dose from Written Directive / Affected Number of Fractions / Expected Range of Doses to Unintended tissue / Estimated Dose to Unintended Tissue Patient A / 18.44 Gy / 65.84 % / 4 / 126 cGy and 175 cGy per treatment fraction / > 28 Gy Patient B / 21.78 Gy / 77.7 % / 3 / 126 cGy and 175 cGy per treatment fraction / > 7 Gy per fraction (total > 21 Gy) Patient C / 23.39 Gy / 83.55 % / 3 / 126 cGy and 175 cGy per treatment fraction / > 7 Gy per fraction (total > 21 Gy) Patient D / 26.84 Gy / 99.41 % / 1 / 126 cGy and 175 cGy per treatment fraction / > 14 Gy for one fraction A software error occurs in the Oncentra Treatment Planning Software version 4.5.2, whenever the built-in tandem and ring applicator model is used. The microSelection afterloader step size of a measured source path is 2.5 mm. An override to the default step size of 5 mm (RDStore), from the step size of the measured source path in the planning software occurred. A change in the source position step size, from 2.5 mm to 5 mm was not realized by the licensee for the ring catheter but was implemented for the delivery plan. The dose distribution, prescription point values, and dose volume histogram readouts were all based on a 5 mm spaced tandem and a 2.5 mm spaced ring. When the plans were exported to the treatment unit and delivered, the afterloading brachytherapy unit utilized a source step size of 5 mm for both the tandem and ring applicators, thus a discrepancy between the planned and delivered dose distributions occurred. The licensee has suspended use of the tandem and ring applicator model within the software and will define all catheters for the tandem and ring applicator manually until further notice of Elekta's software correction. The referring physician and patients have been notified. No adverse health effects were noted for the patients due to the medical events. Activity: 12 Ci Licensee Authorization Update: (8.85 Ci - 5.195 Ci) Date of Incident: 11/8/2016 through 8/15/2017 List any other actions required of DRH [Mississippi Division of Rad Health]: Licensee notified to send 15-day written report. Elekta Notification, FCA-NU-0004, FCO Reference No. 806-01-BTP-001, was sent out to all MS Radioactive Licensees on 8/17/2017, that possess a Nucletron Model microSelectron-HDR. Licensee's written report received August 23, 2017. DRH conducted a reactive inspection of the licensee on September 1, 2017, to determine the cause and further clarify the medical events. The medical events were discussed with the licensee's RSO's, medical physicist(s), and the chair of Radiation Oncology on September 1, 2017, and again on October 17, 2017 and October 18, 2017, with the licensee's medical physicist. Case Closed: Yes Date Closed: 10/19/2017 Notified R4DO (Vasquez) and NMSS Events Notification via email. 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. |
| Where | |
|---|---|
| University Of Mississippi Medical Center Jackson, Mississippi (NRC Region 4) | |
| License number: | MS-MBL-01 |
| Organization: | Mississippi Div Of Rad Health |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+12.72 h0.53 days <br />0.0757 weeks <br />0.0174 months <br />) | |
| Opened: | Jayson Moak 17:43 Aug 18, 2017 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Oct 19, 2017 |
| 52914 - NRC Website | |
University Of Mississippi Medical Center with Agreement State | |
WEEKMONTHYEARENS 529142017-08-18T05:00:00018 August 2017 05:00:00
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