(1189) Evaluating the Relationship Between Temperature Profiles and Radiochemical Purity of tc-99m Sestamibi Using Various Heating Methods to Determine Acceptable Water Bath Alternatives

Objectives: To evaluate the heating profile and resulting radiochemical purity values for Tc-99m sestamibi when utilizing different heating methods during kit preparation, including 10 mL of water placed in a standard 25mm heating block well, a modular heating sand bath, and a bath of thermal metallic beads.

Methods: All sestamibi vials evaluated in this project will be prepared using 150 + 10 mCi of Tc-99m sodium pertechnetate following manufacturer package insert preparation instructions in a total volume of 5ml. After addition of Tc-99m sodium pertechnetate, a temperature probe will be inserted into the vials for measurement of the internal liquid temperature during the heating process. Following baseline temperature assessment, the prepared sestamibi kits will be placed in either a 25mm well diameter heat block with 10 mL of water placed in the well to simulate a water bath, a modular heating sand bath, or a bath of thermal metallic beads. All heating systems will be preheated to an initial temperature of 105° C. A total of three sestamibi kits will be evaluated at several heating time endpoints (2 minute, 5 minute, 8 minute and package insert recommended 10 minute) in each of the three heating apparatuses, with internal temperatures being measured at 30 second time intervals to trace the rate of change of temperature during the heating process. After heating to the designated time point, each vial will be placed into an ice bath to stop the radiolabeling reaction from proceeding, allowing for determination of an accurate radiochemical purity assessment at each of the predetermined time points. Quality control testing will be performed in triplicate using the package insert recommended procedure immediately after each vial is removed from the ice bath. All data will be analyzed to determine variance among the various heating methods.

Results: Data still being collected.

In our lab, previous data has shown that a boiling water bath as recommended in the package insert preparation instructions provides a radiochemical purity above 90% within 1 minute of placing in the heat source, compared to use of a standard heating block with 25mm well which reaches a 90% radiochemical purity at approximately the 5 minute mark. This data also shows that the boiling water bath reached a radiochemical purity of 95% in 2 minutes as compared to the heating block which achieved this in 10 minutes. Based on early data collected in this project, we expect that both a modular heating sand bath and a bath of metallic thermal beads will have a heating and radiochemical purity profile similar to the boiling water bath, while the “mini” water bath method of placing water in a heating block which is commonly used in practice does not significantly improve the overall radiochemical purity of the final product.

Conclusions: N/A