Breast milk activity during early lactation following maternal 99Tcm macroaggregated albumin lung perfusion scan.

A breast feeding infant may receive a radiation dose from ingestion of breast milk following the administration of a radiopharmaceutical to the mother. The Administration of Radioactive Substances Advisory Committee recommendation to interrupt breast feeding may not necessarily apply in the period of early lactation when colostrum is being produced. Following a lung scan using 99Tcm macroaggregated albumin (MAA) on a patient approximately 15 h post partum, radioactivity within breast milk was measured. Milk was expressed approximately every 4 h during the day and samples were counted. The sample radioactivity concentration peaked at 15 h and decayed monoexponentially (half clearance time was approximately 4.8 h). The estimated effective dose to the infant from ingestion alone, had breast feeding not been interrupted, was approximately 0.02 mSv. These data suggest that interruption to breast feeding may not be necessary following administration of up to the diagnostic reference level of 99Tcm MAA during early lactation.