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

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