Imaging of 511 keV gamma photons produced after annihilation
Ring of detectors surrounds patient and detects coincident gamma photons emitted, creating 3D image
Positrons (beta +)
Radioactive decay of positron emitters
Same mass as electrons but positively charged
Travel short distance before combining with free electrons and annihilating; annihilation produces 2 511 keV gamma ray photons
Positron emitter: Radionuclides that emit positrons (beta +)
Positron inside nucleus transforms into neutron (which remains in nucleus) and positron and neutrino (both of which are ejected from atom)
Secondary probability for electron capture: Electron combines with proton from nucleus to become neutron plus neutrino
e.g., F-18 has 97% probability of positron emission and 3% probability of electron capture
ρ⁺ (proton) → η (neutron) + β⁺ (positron) + ν (neutrino) + energy
Total # of protons (atomic number) decreased by 1
Total # of neutrons increased by 1
Mass # unchanged (= # of protons + # of neutrons)
Annihilation
When positron combines with electron
Mass of positron and electron converted to energy in form of 2 511 keV gamma photons given off in opposite directions (~ 180° apart)
511 keV gamma photons part of electromagnetic family (move at speed of light, have no mass, and have no charge)
IMAGING ANATOMY
PET Radionuclides
Flow of Data and Processing
PET Detector Array Design
PET Image Quality
Imaging Features
2D Direct Imaging
2D Cross-Plane Imaging
2D High-Sensitivity Imaging
3D Imaging
PET/CT
PET/MR
Attenuation Correction
Standard Uptake Value
Quality Control
Artifacts
Selected References
Conti M et al: Physics of pure and non-pure positron emitters for PET: a review and a discussion. EJNMMI Phys. 3(1):8, 2016
Ziessman HA et al. Nuclear Medicine: The Requisites, 4th Edition (Requisites in Radiology). Saunders, 2013
Granov A et al. Positron Emission Tomography. Springer, 2013
Chandra R. Nuclear Medicine Physics: The Basics, 7th Edition. Lippincott, Williams and Wilkins, 2012
Bushberg JT et al. The Essential Physics of Medical Imaging, 3rd Edition. Lippincott, Williams and Wilkins, 2011
Saha GB. Basics of PET Imaging: Physics, Chemistry, and Regulations. Springer, 2004
Christian PE et al. Nuclear Medicine and PET: Technology and Techniques, 5th Edition. Mosby, 2004
Valk PE et al. Positron Emission Tomography: Basic Science and Clinical Practice. Springer, 2002
International Atomic Energy Agency. Cyclotron Produced Radionuclides: Physical Characteristics and Production Methods. http://www-pub.iaea.org/MTCD/publications/PDF/trs468_web.pdf. Accessed March 1, 2020
Related Anatomy
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Related Differential Diagnoses
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References
Tables
Tables
KEY FACTS
Positron Emission Tomography
2D and 3D Acquisition Modes
Attenuation Correction
TERMINOLOGY
Definitions
Positron emission tomography (PET)
Imaging of 511 keV gamma photons produced after annihilation
Ring of detectors surrounds patient and detects coincident gamma photons emitted, creating 3D image
Positrons (beta +)
Radioactive decay of positron emitters
Same mass as electrons but positively charged
Travel short distance before combining with free electrons and annihilating; annihilation produces 2 511 keV gamma ray photons
Positron emitter: Radionuclides that emit positrons (beta +)
Positron inside nucleus transforms into neutron (which remains in nucleus) and positron and neutrino (both of which are ejected from atom)
Secondary probability for electron capture: Electron combines with proton from nucleus to become neutron plus neutrino
e.g., F-18 has 97% probability of positron emission and 3% probability of electron capture
ρ⁺ (proton) → η (neutron) + β⁺ (positron) + ν (neutrino) + energy
Total # of protons (atomic number) decreased by 1
Total # of neutrons increased by 1
Mass # unchanged (= # of protons + # of neutrons)
Annihilation
When positron combines with electron
Mass of positron and electron converted to energy in form of 2 511 keV gamma photons given off in opposite directions (~ 180° apart)
511 keV gamma photons part of electromagnetic family (move at speed of light, have no mass, and have no charge)
IMAGING ANATOMY
PET Radionuclides
Flow of Data and Processing
PET Detector Array Design
PET Image Quality
Imaging Features
2D Direct Imaging
2D Cross-Plane Imaging
2D High-Sensitivity Imaging
3D Imaging
PET/CT
PET/MR
Attenuation Correction
Standard Uptake Value
Quality Control
Artifacts
Selected References
Conti M et al: Physics of pure and non-pure positron emitters for PET: a review and a discussion. EJNMMI Phys. 3(1):8, 2016
Ziessman HA et al. Nuclear Medicine: The Requisites, 4th Edition (Requisites in Radiology). Saunders, 2013
Granov A et al. Positron Emission Tomography. Springer, 2013
Chandra R. Nuclear Medicine Physics: The Basics, 7th Edition. Lippincott, Williams and Wilkins, 2012
Bushberg JT et al. The Essential Physics of Medical Imaging, 3rd Edition. Lippincott, Williams and Wilkins, 2011
Saha GB. Basics of PET Imaging: Physics, Chemistry, and Regulations. Springer, 2004
Christian PE et al. Nuclear Medicine and PET: Technology and Techniques, 5th Edition. Mosby, 2004
Valk PE et al. Positron Emission Tomography: Basic Science and Clinical Practice. Springer, 2002
International Atomic Energy Agency. Cyclotron Produced Radionuclides: Physical Characteristics and Production Methods. http://www-pub.iaea.org/MTCD/publications/PDF/trs468_web.pdf. Accessed March 1, 2020
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