PET vs SPECT | Nuclear medicine

[Music] hi everyone my name is pauline and this video is an introduction to nuclear medicine first i will tell you what nuclear medicine is and what the difference is between nuclear medicine and radiology then i will explain the tracer principle and this will help you understand the difference between pet and spect the two types of scans that are most frequently used in nuclear medicine in the end i will talk about each specific scan and its differences nuclear medicine is a medical specialty that uses radioactive tracers or radiopharmaceuticals to visualize how the body is functioning and

what's happening at the cellular and molecular level that is the reason that nuclear medicine is often referred to as a molecular imaging technique one of the main differences with radiology is the fact that pat inspect visualize organ function whereas other imaging methods such as x-rays ct or mri assess the anatomy another key difference relates to how the technology they use works nuclear medicine creates images using different drugs tagged with a radioactive substance which are then injected into the patient's bloodstream images are obtained based on the radioactive decay of the drug radiology on the other hand

uses an external source of energy on the body to obtain an image so if you want to put it in really short terms in radiology the source of energy is an external object while in nuclear medicine it is a radioactive drug from inside a patient nuclear medicine uses radioactive traces to visualize someone's organ function radioactive tracers are made up of carrier molecules that are bounded tightly to a radioactive atom these scary molecules are chosen depending on the purpose of the scan we always attach a radioactive part to the carrier molecule to be able to track

this molecule inside a patient's body for example the carrier methylene diphosphonate is often used in combination with the radioactive substance technetium to assess bone function methylene diphosphate serves as a phosphate analog and binds to the hydroxyapatite crystals in the mineral phase of bone in proportion to the osteoplastic activity this radioactive tracer is a marker for bone turnover the more active the bone turnover the more radioactive material will be seen a fracture in a bone will result in increased osteoblastic activity and thus bone turnover which in turn will lead to increased uptake of the radioactive tracer

the radioactive tracer will then decay by emitting gamma rays which easily penetrate the body and are picked up by a special camera this results in the appearance of a hot spot around the fracture pattern specs are the two main nuclear imaging techniques pet stands for positron emission tomography and uses positron emitting radioisotopes the most commonly used radioisotope is fluorine 18. spect on the other hand stands for single photon emission tomography and uses gamma-emitting radioisotopes the most commonly used radioisotope is tegnesium the radioactive tracers decay by emitting gamma rays which are picked up by a special

camera but they both do it in different way fluoride 18 produces small particles called positrons when a positron encounters an electron which happens very quickly on the body both particles will vanish in a burst of energy this energy comes in the form of two gamma rays that travel in opposite directions and can be detected by the pad scanner to form images technetium decays and produces a single photon of radiation this photon moves out of the body and is detected by the camera combining thousands of these gamma ray detections ultimately result in image creation here's another

picture to illustrate this fluorine-18 which is a positron emitting radioisotope produces positrons positrons encounter electrons and vanish they release two gamma rays that are detected by the camera technetium on the other hand produces a single photon of radiation that is also detected by the camera to form images thank you for watching this video if you enjoyed this video please give it a thumbs up it would really help me if you have questions or remarks please leave a comment below [Music] you