Trying to work out how many atoms of Technetium-99m there are in a 10 MBq dose? Basically trying to work out if the actual weight of the Technetium-99m will affect the "flight" properties of an aerosol labeled with Technegas. Or would it be negligible? Basically will using Technegas to radiolabel an aerosol affect it's properties due to the relatively high mass of the Technetium atoms relative to the existing dry power (e.g. lactose). Lets assume the powder is 20 micron sized particles and the Technetium will "coat" the surface.