Why do doctors wear lead aprons during certain tests and procedures?

Any test that involves x-rays or radioactive isotopes exposes the people nearby to potentially harmful radiation. This is especially true for doctors, nurses and technicians who work around radiation day in and day out.
Think about an interventional cardiologist who evaluates your coronary arteries by performing an angiogram, then does an angioplasty procedure to expand sections of your arteries that are narrowed with built-up atherosclerotic plaque. During these procedures x-rays are used to create pictures of the insides of your arteries and to guide a slender balloon-tipped catheter through your arteries. The special camera used in the catheterization laboratory may be continuously sending out x-rays and taking pictures for 20 minutes or more.
In an entire lifetime, you may have only one angiogram and one angioplasty procedure, if any. But your interventional cardiologist may perform hundreds of procedures a year. That represents a lot of radiation exposure.
Lead is very thick and blocks x-rays. That is why radiology technicians routinely step behind lead-containing walls before pushing the button to take a patient’s x-ray. Your doctor needs to be by your side during many types of procedures and cannot step behind a protective wall. By wearing a lead apron, your doctor is at least partly shielded from harmful radiation.