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PET/CT shielding

Shielding considerations for PET/CT systems must take into account the photon radiation in both the diagnostic imaging energies presented by the CT (<200 keV), as well as the energies resulting from the PET imaging (511 keV). Shielding also needs to be designed to take into account high flux radiation from the CT, as well as the radiation that comes from a patient's taking into account the entire time the patient is present after they are administered with a radiopharmaceutical (because they become a radiation source). 

Two useful documents are available for guidance on PET/CT sheilding.

The IAEA has produced a document which outlines shielding and other considerations in PET/CT. This report is directed primarily at facilities adopting PET/CT technology, and focuses on radiation protection issues. The main topics discussed in this document includes:

  • Current PET/CT technology
  • Clinical methodology
  • Radiation exposure of patients undergoing PET/CT examinations
  • Patient dose management
  • Radiation protection of the staff in a PET/CT facility
  • Training
  • Summary of guidance

The AAPM has also produced a guidance document, which outlines many issues relative to PET/CT shielding, including:

  • Positron-emitting radionuclides
  • Factors affecting radiation protection
  • Rb-82 myocardial perfusion PET studies.
  • How F-18 FDG PET studies are performed.
  • Transmission sources
  • Radioactivity administration
  • Factors affecting dose rates from Radioactive patients
  • Uptake room calculation
  • Imaging room calculation
  • Calculation for rooms above and below the PET facility
  • Dose levels in controlled areas
  • Adjacent rooms on the same level in controlled areas
  • Design considerations
  • PET/CT installations
  • Shielding of the PET tomography from ambient radiation
  • PET facilities located in Nuclear Medicine departments