1. From the central pharmacy order 2 mCi of ⁹⁰Y in 1 mL calibrated at a specific time (when you plan on running this test). Also request that the dose be placed in a 10 mL syringe.
2. Once the dose arrives confirm the order by looking at the label. If necessary determine the theoretical activity by applying a decayed factor.
3. "Dial in" the correct setting and apply the correction factor (for Capentec the setting is 48 and the correction factor is x 10). The reason why you multiple by 10 is that the reading is always off by a factor of 10.
4. Calibration - If the dose does not read is 2 mCi, then adjust the dose calibrator by adjusting your dial so that the reading actually says 2.0 mCi. If an adjustment is needed then record the corrected manual setting for future use.
5. Geometric Variation - Now add 1 mL of saline to the syringe and take a reading. Continue to add 1mL and measure the dose until the total volume equals 9 mL. If the variation is greater than 2% then another correction factor must be determined.
6. The following readings were recorded: 1 mL = 2.0 mCi, 2 mL = 2.0 mCi, 3 mL = 2.0 mCi, 4mL = 2.05 mCi, 5 mL = 2.05, 6 mL = 2.0 mCi, 7 mL = 2.0 mCi, 8 mL = 1.95 mCi, and 9 mL = 1.95 mCi.
7. See the following worksheet.



8. From the above worksheet correction factors must be determined for 4 and 5 mL since variation is greater than 2. The factor is determined to be be 0.975. This value must always be applied to ⁹⁰Y volumes that are 4 to 5 mL. Note that when the correction factor is applied to the reading of 2.05 the correct amount is attained, 2.0 mCi.
9. The same application is shown with 8 and 9 mL with the outcome being 2.0 mCi.

Return to the Table of Content