ENS 43301
ENS Event | |
|---|---|
04:00 Mar 7, 2007 | |
| Title | Agreement State Report - Medical Event |
| Event Description | The State provided the following information via facsimile:
A brachytherapy misadministration involving a 31year old female patient with a history of vaginal cancer was reported to NYS DOH BERP on 3/9/07. The patient was successfully treated to 5590 cGy to the target volume using external beam (IMRT) therapy and she was to receive 2500-3000 cGy via interstitial brachytherapy with both Cesium-137 and lridium-192 (seeds in ribbons) sources. The medical physicist developed a treatment plan as directed by the authorized user/ radiation oncologist using a commercial treatment planning software application. Eleven ribbons with 8 seeds each and an activity of 1.855 mgRaEq per Ir-192 [3.19 mCi] seed were ordered from Best Industries. Hospital owned Cs-137 sources were selected for use. The medical physicist verified source strength of all sources. The oncologist reviewed and approved the plan. He prescribed a total dose of 2500 cGy to be delivered to the 50 cGy-isodose line for a total treatment time of 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. At 2:30 PM on 3/6/07 the sources were placed into the patient. A Syed template was used to place the ribbons and the Cs-137 sources were loaded into a tandem applicator. On 3/7/07, late in the morning, the medical physicist performed a manual check of the treatment plan calculations and identified a significant discrepancy - the hand calculations indicated a significantly higher dose rate than what was generated from the treatment planning software. An investigation ensued, which included consultation with the TPS vendor's application specialist. After several hours of investigation it was determined that the original treatment plan was in error, and at 5:30 PM on 3/7/07, after 27 of the intended 50 hour5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> treatment time, the radiation oncologist decided to remove the sources [from the patient]. Instead of the intended 2500cGy, the patient received an estimated dose of 4590 cGy and the anterior rectal dose was approximately 7300 cGy. The licensee provided a written report as required, and DOH staff performed an on-site investigation on 3/21/2007. Cause and contributing factors: 1. The primary error was the use of an inappropriate Dose Rate Factor in the TPS. The value used corresponded to the DRF for Air Kerma however the source strength entered was in MgRaEq. The physicist should have changed the units of source strength or entered the correct DRF. 2. Changing the units of activity in the TPS does not generate a prompt for a new Dose Rate Constant. 3. During the physics review it was determined that acceptance testing of this treatment planning software did not include Iridium-192. The acceptance testing covered Cesium -137 and Iodine -125 seeds which where the only materials being used at the time. If this testing had been performed the physicist would have been more likely to recognize that the treatment planning system does not automatically select the correct dose rate factor when the source strength units are changed. 4. There was no check of the preplan before the seeds arrived although there was sufficient time (sources ordered 2/27/07). The plan was approved on 3/6/07. 5. Neither the physicist nor the radiation oncologist had prepared a treatment with Ir-192 in six years and the physicist had not used this particular TPS for Ir-192 implants. It would have been prudent to have an additional review or outside review in order to verify there were no oversights or errors. 6. The double check was not done until after the day after sources had been implanted. Again while the physicist was observing the minimum requirements of Part 16 it would have been prudent to perform a check of the calculations either prior to the implant or immediately thereafter. Corrective action: The policy and procedures have been changed to require a check of calculations for any single fraction brachytherapy treatment to be performed and approved prior to initiation of treatment. Patient condition and follow-up: The radiation oncologist disclosed that the patient is at risk for radiation cystitis, rectal proctitis and more importantly, fistula formation between the rectum and the vagina. The patient will be monitored closely over the next year by both her gynecologic oncologist and the radiation oncologist. The patient is currently being treated with broad spectrum antibiotics along with daily treatments in a hyperbaric oxygen chamber. NY Event No: NYS-DOH 07-001
This event has been reviewed and determined to be a reportable medical event. 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 | |
|---|---|
| Not Provided New York (NRC Region 1) | |
| License number: | Not Provided |
| Organization: | New York State Dept. Of Health |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+900.93 h37.539 days <br />5.363 weeks <br />1.234 months <br />) | |
| Opened: | Robert Dansereau 15:56 Apr 13, 2007 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Apr 16, 2007 |
| 43301 - NRC Website | |
Not Provided with Agreement State | |
WEEKMONTHYEARENS 550062020-11-23T04:00:00023 November 2020 04:00:00
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