What causes you to need to get an injection to do a bone scan to check for a stress fracture?

Radiotracer: A nuclear medicine bone scan is used to evaluate for conditions affecting bones including cancer, fractures, degenerative diseases etc. The radiotracer or radioactive material used is injected through a vein quickly reach your bones where it is deposited. A gamma camera is used to detect the radiotracer and images are created. The radiation is cleared from your body mostly in urine.

Bone metabolism: Radiotracer technetium 99m mehylene diphosphonate or similar agent is injected intravenously to be transported by blood stream to the bones. Full deposition usually takes 2 to 3 hours. This agent goes where there is increased bone metabolism or repair of bone, such as fractures, tumors, arthritis, and infection. It detects subtle changes, sometimes not noticed on routine imaging.