An examination of Dose Loss of Tc99m-MAA Due to Needle Cap Adsorption and Transportation

Introduction: The purpose of this study was to determine if the radiopharmacy should change needle caps immediately after dose draw to reduce dose loss or send their doses using luer locks instead of needle caps to reduce dose loss.

Methods: A two part study of the degree of adsorption was documented with a sample size of 80 doses of 111 - 185 megabecquerel (MBq) of Tc99m-MAA using needle caps and B Braun Medical luer cap dual function male and female ends. For comparison of initial dose loss upon dose draw in the needle, 40 doses were assayed with the same needle cap used to draw up the dose, then re-assayed with a clean needle cap in which the percentage lost was calculated. Similarly, for the comparison of adhesion of luer locks and needles, 80 doses divided into two groups of 40 were drawn up and assayed, 40 with needle caps and 40 with luer locks. The doses were then re-assayed with either a new needle cap or luer lock after sitting for 1-1.5 hours and mock transported.

Results: For initial dose loss during dose draw the percent lost from initial dose draw up exclusively in the needle was 6.2%. For the comparison of adhesion in the needle versus the luer lock after transport, 82.5% of the time >10% of the dose was lost in the needle. Comparatively, 22.5% of the time >10% of the dose was lost using a luer lock.

Conclusions: The radiopharmacy should not change the needle cap on doses after dose draw to reduce dose loss during initial dose draw. The radiopharmacy should send their doses using luer locks rather than needle caps to reduce dose loss.