Draft report: Radiological Protection in PET and PET/CT


Positron Emission Tomography (PET) is a nuclear medicine imaging procedure used today almost exclusively in multimodal imaging particularly with computed tomography (CT) but also with magnetic resonance (MR), rather than alone. Its utilisation rates are growing as clinical indications expand with the addition of new PET radiopharmaceuticals. In some countries, PET/CT scans currently make up about 10% of all nuclear medicine examinations and about 20% of the patient effective dose delivered in nuclear medicine. Radiation doses depend not only on the administered activity, but also on the CT scan utilisation. Shorter half-lives of PET radionuclides and the high energies of annihilation photons emitted present particular challenges for staff radiological protection, which are compounded because patients are required to rest for an extended period between administration and imaging. Occupational doses in PET can be of few mSv per year, and skin doses to the fingers from manipulating PET radiopharmaceuticals can exceed the annual skin dose limit of 500 mSv if proper protection measures are not followed. Public exposure is not a cause for concern, and no special recommendations are needed to limit the release of the patient after the PET scan. However, patients and clinicians remain concerned and therefore,this report provides guidance on not only occupational, but also patient, and public radiological protection in PET and PET/CT. A brief section on PET/MR is also provided.The technology involved and the way in which it is used together with the facility design has a direct impact on patient and staff dose. Consequently, the principles of operation of both the cyclotron used for production of the radionuclides and of the scanner are reviewed in this report; the report describes optimal facility design, equipment life cycle considerations, and work flow for the radiopharmaceutical agents. The justification of the PET procedure should be established considering also the technology available, and when performed in a PET/CT scanner, the CT protocol should correspond to the objective of the CT examination. Distinct considerations are provided for the radiological protection related to the medical exposure of patients, carers/comforters, and research volunteers, including patient dose estimation, strategies to reduce the dose, and the special cases of patients who are breast feeding or pregnant, and paediatric patients. Sources of exposure to staff working in PET facilities have been reviewed, and records show that dose depends not only on the protective methods but also on the individual practices, education, and quality assurance program. Therefore, procedures to reduce staff dose are provided together with guidance for staff monitoring. Optimisation of radiological protection for PET should be within the frame of a dose management and quality assurance program, which describes the radiological protection program and includes metrics to evaluate the degree of achievement. In addition, the health professionals that perform the procedures must obtain proficiency in radiological protection and safety through formal, accredited education, training, and continuous professional development.

An online workshop will be held as part of this consultation on Monday, 18 September, 2023, from 08:00(EST)/12:00(GMT) to 10:30(EST)/14:30(GMT). Further details will be provided soon. We anticipate your active participation and remind you that comments should be submitted using the link below, even if discussed during the workshop.

ICRP routinely solicits comments on most draft documents prior to publication, with the exception of those that are basically compilations of computed values such as specific absorbed fraction values or dose conversion factors.

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Draft Document