An Authorized User physician from the University of
Michigan Department of Radiation Oncology planned two liver infusion treatments for a patient with unresectable hepatocellular carcinoma using
Y-90 Theraspheres. As part of treatment preparation, an MRI was performed on the patient to determine the patient's liver segment volumes. Liver segment volumes are used in calculating the
Y-90 activity needed to deliver the prescribed radiation dose to particular segments of the liver. The first treatment was to the right lobe and medial segment of the patient's liver and was performed on 12/15/2010. It proceeded without incident and in accordance with the written directive.
The Authorized User physician scheduled a second separate treatment to the patient's left lobe to be performed on 3/9/2011. The Authorized User ordered a 74.4 Gy dose to the left lobe of the liver. The medical physicist calculated a corresponding dosage of 60.5 mCi of Y-90 to be infused into the left lobe of the liver.
However, in arriving at the Y-90 activity needed, a medical physicist used the liver segment volumes for the right lobe and medial segment combined instead of that for the left lobe. The volume of the right lobe and medial segment is much larger than that for the left lobe. As a result, the Y-90 dosage of 60.5 mCi exceeded what was actually needed to deliver the prescribed dose of 74.4 Gy. The Y-90 was infused into to the left lobe on 3/9/2011 at approximately 10 [EST]. Based on the Authorized User's reassessment of the left lobe volume, the dose to the left lobe is calculated, post-administration, to be 159.4 Gy.
The patient was notified of the event on 3/9/2011. The referring physician was also notified on the morning of 3/10/2011. The Authorized User physician has concluded that the elevated radiation dose to the patient's liver will not result in permanent medical damage or loss of function. Upon initial investigation this event appears to possibly be due to a problem in transcription however causes and corrective actions are still being evaluated.
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.