AAPM Task Group 108: PET and PET/CT Shielding Requirements

• Published in: Medical physics (Lancaster) Vol. 33; no. 1; pp. 4 - 15
• Main Authors: Madsen, Mark T., Anderson, Jon A., Halama, James R., Kleck, Jeff, Simpkin, Douglas J., Votaw, John R., Wendt, Richard E., Williams, Lawrence E., Yester, Michael V.
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01-01-2006
• Subjects: ANNIHILATION; BETA-PLUS DECAY; biological tissues; Cameras; Cancer; Computed tomography; computerised tomography; FLUORINE 18; GAMMA CAMERAS; Image detection systems; Image scanners; MATERIALS SCIENCE; Medical imaging; MEETINGS; MEV RANGE 01-10; PARTICLE ACCELERATORS; PATIENTS; pharmaceuticals; PHOTONS; Positron annihilation; POSITRON COMPUTED TOMOGRAPHY; positron emission tomography; Positron emission tomography (PET); Positron-Emission Tomography - standards; Positrons; Practice Guidelines as Topic; Radiation Dosage; Radiation Monitoring - methods; Radiation Monitoring - standards; Radiation monitoring, control, and safety; RADIATION PROTECTION; Radiation Protection - methods; Radiation Protection - standards; RADIATION SOURCES; radioactive decay periods; radioactive sources; Radioactivity; RADIOLOGY AND NUCLEAR MEDICINE; RADIOPHARMACEUTICALS; REVIEWS; Risk Assessment - methods; Risk Assessment - standards; Risk Factors; SHIELDING; Societies, Scientific; Sources of radioactive nuclei; Surveys and tutorial papers; resource letters; Tomography, X-Ray Computed - standards; United States; United States
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.2135911

The shielding of positron emission tomography (PET) and PET/CT (computed tomography) facilities presents special challenges. The
0.511
MeV
annihilation photons associated with positron decay are much higher energy than other diagnostic radiations. As a result, barrier shielding may be required in floors and ceilings as well as adjacent walls. Since the patient becomes the radioactive source after the radiopharmaceutical has been administered, one has to consider the entire time that the subject remains in the clinic. In this report we present methods for estimating the shielding requirements for PET and PET/CT facilities. Information about the physical properties of the most commonly used clinical PET radionuclides is summarized, although the report primarily refers to fluorine-18. Typical PET imaging protocols are reviewed and exposure rates from patients are estimated including self-attenuation by body tissues and physical decay of the radionuclide. Examples of barrier calculations are presented for controlled and noncontrolled areas. Shielding for adjacent rooms with scintillation cameras is also discussed. Tables and graphs of estimated transmission factors for lead, steel, and concrete at
0.511
MeV
are also included. Meeting the regulatory limits for uncontrolled areas can be an expensive proposition. Careful planning with the equipment vendor, facility architect, and a qualified medical physicist is necessary to produce a cost effective design while maintaining radiation safety standards