In pet technique a radioactive substance is introduced into the body to assess structure and functions of tissues .the technique was invented in 1970 . in this method structural images are not produced , but it gives information about the chemical activity of tissues or organs. The blood flow direction can be examined through this technique. In this type of imaging the tissues first labeled by a radioactive substances . these radio active substances emit particles named by positrons. The pet scanner will detect these positrons. The emission of positron from different body parts varied. This detector is interfaced with a computer , after mathematical calculations an image is developed . now a days pet is used to find heart diseases and tumors.

Endoscopy

In endoscopy we use tube like instruments to look at organs. The instrument used for this technique is known as endoscope. In this technique a tube like instrument is introduced into the body . the instrument is connected to a computer , where the doctor can see the internal organs. The endoscope is access through the natural openings of the body such as anus, mouth etc.