What Is PET?• Nuclear medicine scan, Functional imaging technique.• Quantifiable – amount of radiation depends on rate of metabolic activity• non-invasive, but does involves exposure to ionizing radiation,• Usage of radioactive isotopes (radiopharmacons) emitt β⁺ particles
How Does PET Work?• Administration of radiopharmacon• Decay of isotope internally, accumulation ofradiopharmacon in diseased tissue.• Electron interaction annihilation emission of 2 gamma photons.• Scintillating detectors ( gamma camera).• Collection and storage of data reconstructionof 2D distribution map.• Most scans today are combined with CT.
Collection Of Data – Lines Of Conicidence Linear sampling – defining parallel coincidence sampling paths.Each detector can beoperated in multiplecoincidence with manydetectors across from it.
Radioactive Isotopes Common isotopes used for PET examinations and their main propertiesIsotope 11 C 13 N 15 O 18 FHalf-life (minutes) 20.3 9.98 2.05 110Nuclear reaction 14 N (p,α) 11C 16 O(p,α) 13N 14 N(d,n) 15O 18 O (p,n) 18F Manifactured by cyclotrons. Cyclotron = accelerator with a circular path enforced by a magnetic field.
Medical Fields Of Application• PET and PET/CT scans are performed to:• detect cancer.• determine spread of cancer• Determine effectiveness of treatment, such as cancer therapy.• Detect return of a cancer.• determine blood flow to the heart muscle.• determine the effects of a heart attack, or myocardial infarction, on areas of the heart.• Identification whether certain areas of the hear would or wouldn’t benefit from surgery.• Evaluate brain abnormalities; tumors, memory disorders, seizures and other central nervous system disorders.• To map normal human brain and heart function.
Benefits And Risks Of PET Benefits of PET: •Image information unique- high sensitivity •yields most useful information compared to other imaging techniques from a pathological view. •High spatial resolution • more precise, cheaper, and more esthetical than exploratory surgery. •Can detect a disease at an earlier stage than ex. CT scans or MRI. •Result in low radiation exposure. (obs. not more than any other type of imaging method!)Risks with PET:•Allergic reactions to radiopharmaceuticals may occur but are rare.•Injection of the radiotracer may cause slight pain and redness which shouldrapidly resolve.•Expensive – due to cyclotrons needed to produce short lived radionuclides.•Low accecssbility• takes time