ENS 42207
ENS Event | |
|---|---|
06:00 Sep 12, 2005 | |
| Title | Illinois Agreement State Report - Medical Misadministration |
| Event Description | The State provided the following information via email:
On December 14, 2005 the licensee's Radiation Safety Officer, [name deleted], called the Division and forwarded information describing a medical misadministration that involved a brachytherapy dose that was greater than 10 percent from the intended treatment. The misadministration had occurred some months ago. The event was discovered as a result of a review of past treatments during an attempt to understand, what appeared to be, anomalies for certain cases. In a particular case on September 12, 2005, a patient began treatment for cervical cancer with a 'Fletcher Suit' manual brachytherapy afterloader using Cs-137 sealed sources. A transposition error was made in the digitization of the patient's lateral film used to construct the applicator's position and thus the positions of the radiation sources relative to the locations of the dose calculation points. Therefore, the digital locations used for mapping and treatment planning of points 'right A' and 'left A' relative to the sources were incorrectly determined. These calculated points used in the treatment planning were located in a region of lower dose rate within the tumor than the true anatomical 'A points', at which the prescription should have been defined. As a result, the prescription/final treatment plan used incorrect lower dose rate points and called for the use of an erroneously high source loading. Based on a retrospective analysis, instead of the calculated average dose rate of 0.545 Gy/hr for the erroneous 'A points', the actual delivered averaged dose rate to the true 'A points' was 0.74 Gy/hr. This resulted in an average dose of 54.3 Gy delivered to the true points A instead of the planned 40.0 Gy. The dose to the other points, namely rectum and bladder, were calculated correctly because their location did not involve the digitization step in which the transposition error occurred. These doses, which were calculated correctly, were all within acceptable limits. Only the tumor dose was in excess of the intended dose. This event occurred because of a misunderstanding concerning use of the new treatment planning system (TPS) that was being introduced into the clinic. The TPS allows digitizing either a right or left lateral film for locating the sources, bladder and rectal points for calculating doses. However the location of target point 'A', which is used for dose prescription, must be determined manually. Therefore a separate program is used which requires digitizing the source applicator on AP and lateral films to localize these points. In this additional step, the orientation of the lateral film on the digitizer was reversed left to right from what the program required, resulting in sign reversal of the anterior-posterior coordinate of the left and right 'A points'. This error was discovered in December, when looking into why positions of calculated points sometimes appeared unusual. This error was not caught at the time of the original implants. Once this potential source of dose discrepancy was discovered, the licensee reviewed all the patients whose dosimetry plans were determined with the new TPS since treatments were first initiated some three months ago. Three total patients were identified. The magnitude of the effect was found to also depend upon the orientation of the applicator in the patient. Only the case described above had those adverse complications which resulted in a medical event. A review of the two additional dosimetry plans showed that due to the orientation of the apparatus in the patient, the dose to the true prescription point was less than 5% greater than the planned dose. The clinical consequences for the patient concerned in this report are being evaluated by physicians. Four Cs-137 sealed sources with a total activity of 178 mCi were inserted into the patient. The planned averaged point A dose was 40.0 Gy and the actual administered dose was 54.3 Gy. Other than the 'point A' dose, no other dose calculation points were outside of the treatment specifications. The physicians are reviewing the revised dosimetry plans to determine if there will be any increased risk of complications for this patient. The clinical consequences for the patient concerned in this report are being evaluated by physicians. The dose at the various calculation points were: Dose points/Planned Dose (Gy/hr)/Actual Dose (Gy/hr) Right A/0.56/0.74, Left A/0.530.74, Right B/0.18/0.18, Left B/0.17/0.17, r-rectum/0.33/0.37, s-rectum/0.35/0.39, t-rectum/0.31/0.32, u-rectum/0.21/0.21, B-bladder/0.47/0.43. This matter will be included during an pending routine inspection which will be conducted in the next 30 days. Corrective Actions: Action Number / Corrective Action: 1 PROCEDURE MODIFIED 2 PERSONNEL RECEIVED ADDITIONAL TRAINING Patient Information: Patient Number: 1 Patient Informed: N Date Informed: Therapeutic BRACHY, MANUAL AFTERLOADER Organ: CERVIX Dose: 5430 rad 54.3 Gy % Dose Exceeds Prescribed: 36 % Dose is Less Than Prescribed: Effect on Patient: UNKNOWN Administered By: PHYSICIAN Dose to Family: 0 rem 0 Sv Dose to Newborn: 0 rem 0 Sv Dose to Fetus: 0 rem 0 Sv Source of Radiation: Due to the nature of the event, this matter was reported to the U.S. NRC Operations Center on December 15, 2005. It was assigned event number 42207 Source Number: 1 Form of Radioactive: SEALED SOURCE Radionuclide or Voltage (kVp/MeV): CS-137 Source Use: BRACHYTHERAPY Activity: .178 Ci 6.586 GBq Manufacturer: Model Number: Serial Number: Device/Associated Equipment: Device Number: 1 Device Name: MANUAL AFTERLOADER Model Number: Manufacturer: UNKNOWN Serial Number: Reporting Requirement: 32 IAC 335.1080 - Any administration of radioactive materials that results in a 'reportable event' (misadministration), licensee shall notify the agency by telephone NLT next day after licensee ascertains and confirms that a 'reportable event' has occurred. Mode Reported: Written Illinois Item No. IL-050073 |
| Where | |
|---|---|
| University Of Chicago Hospital Chicago, Illinois (NRC Region 3) | |
| License number: | IL-01678-02 |
| Organization: | Illinois Emergency Mgmt. Agency |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+2261.43 h94.226 days <br />13.461 weeks <br />3.098 months <br />) | |
| Opened: | Daren Perrero 12:26 Dec 15, 2005 |
| NRC Officer: | Mike Ripley |
| Last Updated: | Dec 15, 2005 |
| 42207 - NRC Website | |
University Of Chicago Hospital with Agreement State | |
WEEKMONTHYEARENS 575472025-02-05T06:00:0005 February 2025 06:00:00
[Table view]Agreement State Lost I-125 Seed ENS 553102021-06-15T05:00:00015 June 2021 05:00:00 Agreement State Medical Event - Underdose ENS 540192019-04-19T05:00:00019 April 2019 05:00:00 Agreement State Agreement State Report - Lost and Recovered I-125 Source ENS 531272017-12-15T06:00:00015 December 2017 06:00:00 Agreement State Agreement State Report - Underdose ENS 422072005-09-12T06:00:00012 September 2005 06:00:00 Agreement State Illinois Agreement State Report - Medical Misadministration 2025-02-05T06:00:00 | |