Method for preparation of Tc-99m-Tin colloid with optimal particle size for sentinel node visualization

This study was undertaken to develop a method for preparation of Tc-99m-tin colloid with optimal particle size. After mixing tin colloid solution with Tc-99m solution we measured the distribution of the colloid particles with different size filters under the following different conditions: time after the mixing (15, 30 and 60 min), temperature (4, 27 and 34 C), ratio of Tc-99m and colloid solution and stirring methods. The proportion of large particles increased with time after mixing. The distribution of particles did not differ at 4 and 27 C, but at 34 C the proportion of large particles was higher. At the ratios of 1:2 and 1:4, using the inversion method, the proportion of small and medium particles was about 30% each. The optimal method is a mixture ratio of 1:2-1:4 and the inversion method at room temperature, and it should be injected within 30 min after preparation. (author)