Dispensing and Administration of Radiopharmaceuticals for Dacryoscintigraphy

Abstract

Dacryoscintigraphy was first introduced in 1972 as a method to detect and localize obstructions of lacrimal drainage under physiologic conditions.1 It has since become commonly used in the evaluation of epiphora.2–7 Briefly, about 50–100 μCi of Technetium Tc-99m sodium pertechnetate or Tc-99m sulfur colloid in a volume of about 10–15 μL is placed on the surface of the eye.3,5 The transport of the radioactive tracer from the conjunctiva into the lacrimal drainage system and flow through the drainage duct to the nasal cavity can then be followed through images obtained using a gamma camera. This radiopharmaceutical dose has customarily been administered onto the surface of the eye using a micropipette.2–6,8–12 Although feasible for administration, dispensing of the radioactive dose in this manner is problematic, especially related to issues of sterility and radioactive contamination. Using a micropipette necessarily requires withdrawal of the radiopharmaceutical solution from an open container into an unsealed pipette tip, which makes sterility difficult to maintain. Leakage of radiopharmaceutical solution from the unsealed pipette tip, resulting in radioactive contamination of the immediate surroundings, may be difficult to avoid. Because these sterility and radioactive contamination issues preclude transportation of the loaded micropipette, it must be filled with the radiopharmaceutical at the immediate location of use. Hence, dispensing (and administration) of the radiopharmaceutical dose in a closed, sterile apparatus taken from a sealed, sterile source would be desirable. The purpose of this study was to evaluate alternative devices for dispensing and administration of radiopharmaceuticals for dacryoscintigraphy.