Radiation doses from technetium-99m DTPA administered as an aerosol

A model is presented which enables radiation doses following the administration of technetium-99m diethylenetriaminepentaacetic acid ([99mTc]DTPA) aerosol to be calculated. The organ with potentially the highest radiation dose is shown to be the bladder wall. Radiation doses to the lungs, kidneys, and bladder wall and the effective whole-body dose are discussed in terms of the lung clearance rate of [99mTc]DTPA aerosol and the pattern of bladder voiding. The model indicated the influence of urine flow rate on bladder dose assuming a critical volume at which bladder voiding occurs. It is concluded that significant reductions in radiation doses may be achieved by encouraging patients or subjects undergoing investigations using [99mTc]DTPA aerosols to drink freely following the study.