Positron Emission Tomography
Medical equipment used to perform positron emission tomography scan
The idea for these types of exams came about thirty years ago. In physical concepts we know that it is only possible to see or detect something that can emit photons or electromagnetic radiation, so one of the options that scientists found to see the inside of the human body, in order to detect diseases, was through the injection of substances, called markers or tracers, in which radioactive elements are inserted that work as indirect sources of photos.
The most commonly used radioactive elements for insertion into the human body are elements such as carbon-11, fluorine-18, oxygen-15, etc.
The elements injected into the body, and which serve as photon sources, are artificial radioactive isotopes. These isotopes have an unstable nucleus that emits positrons that collide with electrons in the human tissue being examined. After the collision between positrons and electrons, both annihilate each other, generating a pair of gamma rays, that is, generating high energy photons.
Exams performed through positron emission tomography provide images of blood flow and other biochemical functions of the human body, such as, for example, glucose metabolism in the brain and rapid variations in activity in different areas of the human body, characteristics of carcinogenic processes.
We can say that the major limitation of the use of positron emission tomography is in the place where the exam is performed, which must be close to a center that produces the radioactive elements necessary for its use.