Prime objective of this lecture is to present on Nuclear Medicine. Major focus on Tracers and Sterilization. It is important to be able to study internal organs, or tissues, without the need for surgery. In such cases, radioactive tracers can be injected into the body so such studies can take place. The path of these tracers can be detected using a gamma camera because of their radioactivity. Tracers consist of two parts: A drug which is chosen for the particular organ that is being studied. A radioactive substance which is a gamma emitter.