Abstract
Objective: Strontium-89 (Metastron®, Medi-Physics Inc., Arlington Heights, IL) has recently received U.S. Food and Drug Administration approval as a therapeutic agent for relief of bone pain in patients with painful skeletal metastases. However, there are no calibration settings specified for measurement of 89Sr in a dose calibrator.
Methods: Our institution developed a technique to determine the correct dose calibrator setting for measurement of 89Sr both in the vial, as received from the manufacturer, and in the syringe for patient administration. The labeled activity in the 89Sr vial was initially decay-corrected to the current date and time. The vial was then placed in a dose calibrator (CRC®-12, Capintec, Inc., Ramsey, NJ), and the potentiometer was adjusted until the displayed activity and the calculated activity were the same (after the displayed reading was multiplied by a conversion factor of 100). This technique was then repeated using another Capintec dose calibrator. The same procedure was applied to the 89Sr measurement in the syringe. The amount of 89Sr activity withdrawn into the 6-ml syringe was determined by subtracting the residual activity contained in the vial (using the same dial setting for the vial) from the original vial activity.
Results: The calibration settings obtained for 89Sr measurement in a vial or syringe were very similar on both dose calibrators.
Conclusion: This technique may be useful to others who wish to determine dose calibrator settings for measurement of 89Sr.