How is radiation used to sterilize medical equipment?

Gamma rays are high energy electromagnetic waves. Therefore, they can only be stopped by thick lead. This means they can easily pass through medical equipment, like syringes. If the syringe is kept in a sealed bag and gamma rays are passed through, they will kill off all living tissue such as viruses and bacteria. This stops the bacteria from reproducing, multiplying and growing, which sterilises the hospital equipment.