Abstract
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Objectives: Lymphoscintigraphy is used to map the lymph drainage pattern and to localize a sentinel lymph node. There are numerous configurations of 99mTc-filtered sulfur colloid used for these studies. The purpose of this study was to evaluate the stability of various lymphoscintigraphy unit doses over time.
Methods: Sulfur colloid was prepared according to approved protocol. A unit dose of 99mTc-sulfur colloid was drawn and used as the standard. An aliquot of the reconstituted kit was then filtered through a 0.1 micron filter from which three unit doses were dispensed. Equal volumes of 0.2 mL of lidocaine HCl 1% was added to one of the doses while a 10:1 ratio of 1% lidocaine and 8.4% sodium bicarbonate was added to a separate unit dose. All doses were calibrated for 1 mCi six hours post preparation and were standardized to a final volume of 0.5 mL. Quality control testing was performed via thin layer chromatography along with pH measurements at 0, 4, 6, 8, 10, and 12 hours post dispensing of the unit doses.
Results: All unit dose configurations revealed product purities greater than 92% with no substantial change over the 12 hours. The pH of the samples did not change over the time period evaluated. The average product purity along with the pH for each configuration are summarized in Table 1.
Conclusions: All unit dose configurations analyzed over 12 hours showed no effect on pH and revealed radiochemical purities greater than 92% with no substantial change over the time period evaluated.