AGREEMENT STATE REPORT - Y-90 THERASPHERE UNDERDOSE TO LIVER
The following email was received from the State of Ohio:
"On Wednesday, November 26, 2014 at 1129 [EST], the Interventional Radiologist Authorized User [AU] physician began to administer the prescribed activity of 1.38 GBq Y-90 micro-spheres (Theraspherer) for an estimated dose of 125 Gy to segment 7 of the right liver lobe. After a couple of 20 cc syringes of saline had been pushed through the administration kit, the Nuclear Medicine technologist made an ion chamber measurement of the dose vial and tubing set and observed a very high reading of 2.5 Roentgens/hour using a Keithley 451B/RYR, serial number 2935, ion chamber with the beta window open. This was a very high measurement, so the AU physician continued to push an additional 6 syringes of saline for a total of 8 syringes through the administration set with very little reduction in the ion chamber reading. At that point the AU physician decided to call an end to the therapy.
"The administration set was moved out of the room and using the manufacturer's template, the Nalgene jar containing the dose vial and tubing set in the plastic beta shield was measured as 0.55 mR/hr versus a pre-therapy measurement of 2.3 mR/hr. This meant that approximately 24 percent of the dose remained in the dose vial and/or tubing set and micro-catheter.
"The RSO then asked the Nuclear Medicine technologist to take the Nalgene jar to the hot lab to measure the dose vial, tubing set and micro-catheter individually in the dose calibrator. Each of the items were carefully wrapped and measured in the dose calibrator using a calibration factor of 048 for the dose vial and 086 for the tubing sets. The Capintec CRC 15-R, serial number 156151, dose calibrator measurements were 0.009 GBq in the dose vial, 0.31 GBq in the 'D' line tubing set and 0.038 in the micro-catheter for a total of 0.357 GBq of the 1.44 GBq decayed to the time of administration which equals about 24.8 percent of the total dose.
"The prescribed dose was 1.38 GBq which would deliver about 125 Gy to the segment 7 of the right liver lobe; subtracting the 0.357 GBq the calculated dose to the liver segment was 98.15 Gy or about 78 percent of the prescribed dose.
"The Radiation Safety Officer contacted BTG International (Canada) to file an incident report and provided all of the specific details of the incident (Incident Report Number: OTT-PC-14-0073). The BTG representative asked to check with the AU physician to see if he administered the saline at approximately 20 cc/min, and not less than 10 cc/min so that the micro-spheres would not settle out of suspension during the administration. The tubing set and dose vial will be stored for decay-in-storage and returned to the manufacturer for further analysis.
"After interviewing the Authorized User physician following the case, he said that there was no medical reason related to the patient that lead to the under dose, and that he intended to administer the entire 125 Gy to the liver segment throughout the therapy. He also mentioned that the delivered 98.15 Gy to a small segment of the liver (segment 7) was therapeutic and provided optimal treatment dose to the tumor. He explained that the delivered dose that differed by more than 20 percent from the prescribed dose had no consequences to the patient and there is no requirement to repeat the treatment. He also mentioned that he pushed the saline with at least a rate of 10 cc/min or higher not exceeding 20 cc/min.
"According to the Ohio Administrative Code, 3701:1-58-101, Report and Notification of a Medical Event, the total dose exceeded 0.5 Sv (50 rem) to an organ and differed from the prescribed dose by more than 20 percent, and therefore, met the reporting criteria. A telephonic report was made by the Radiation Safety Officer to the Ohio Department of Health at 1615 [EST] on 11/26/2014 regarding this incident. The Authorized User physician that administered the therapy was the referring physician and notified the patient the day of the procedure. The Nuclear Medicine imaging following the therapy indicated that the microspheres were administered to the correct liver region."
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. |