For millennia, doctors hoping to catch a glimpse of what’s happening inside a patient had very few options aside from cutting the body open. But that changed in 1957, when American electrical engineer Hal Anger invented the gamma camera and doctors were able to see what was going on inside of cells.
Every year, doctors order as many as 40 million medical imaging scans that require a radioactive isotope called technetium-99m (Tc-99m). The scans help them diagnose cancer, heart disease and other serious maladies.