This medicine helps your doctor take pictures of your lungs to see how well air moves in them.
For adults, the usual inhaled dose is about 40 MBq; children receive smaller doses.
You will breathe in Technegas using a mouthpiece. You might get oxygen first. Your doctor or nurse will guide you on how to breathe it in, and you may need to lie down so the medicine spreads evenly in your lungs.
An overdose is highly unlikely because doses are carefully prepared and checked by medical staff.