Swiss survey and national diagnostic reference levels for PET/CT examinations in adults.

PURPOSE: Diagnostic Reference Levels (DRLs) are benchmarks for optimizing radiation doses in medical imaging. This study establishes new national DRLs (NDRLs) for PET/CT examinations in Switzerland based on a multicentre survey. METHODS: Administered activities for PET examinations and dose indicators for localization / attenuation correction (AC) CT scans were collected in Swiss nuclear medicine (NM) institutes between April and September 2025. RESULTS: Data from 45 PET devices in 35 NM institutes were analysed (100% response). New NDRLs were defined as administered activitiesfor nine PET examinations: general oncology with [18F]FDG (3.1 MBq/kg; 220 MBq), prostate cancer imaging with [18F]F-PSMA (3.1 MBq/kg; 260 MBq), neuroendocrine tumour imaging with [68Ga]Ga-DOTA (2.1 MBq/kg; 160 MBq), brain tumour imaging with [18F]FET (3.0 MBq/kg; 200 MBq), inflammation/infection with [18F]FDG (3.3 MBq/kg; 230 MBq), neurological examinations with [18F]FDG (2.9 MBq/kg; 200 MBq) and [18F]flutemetamol (2.8 MBq/kg; 185 MBq), parathyroid imaging with [18F]fluorocholine (2.8 MBq/kg; 200 MBq), and myocardial perfusion with [82Rb]rubidium chloride (8.6 MBq/kg; 630 MBq/injection). Updated volume computed tomography dose index (CTDIvol) and dose-length product (DLP) for four AC CT were defined for vertex to mid-thighs (3.8 mGy/410 mGy·cm), vertex to feet (3.8 mGy/680 mGy·cm), brain (6.1 mGy/150 mGy·cm) and cardiac scans (1.3 mGy/40 mGy·cm). CTDIvol for AC CT varied considerably among NM institutes (1.0 - 7.5 mGy for vertex to mid-thighs), indicating potential for protocol optimization and standardization. The established NDRLs tended to be lower than international reference levels, and the corresponding dosimetric indices were generally low. CONCLUSION: The survey provides an overview of administered activities and CT doses in adult PET/CT examinations in Switzerland and establishes new NDRLs to guide protocol optimization.