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

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.

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.

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 (CTDI_vol) 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). CTDI_vol 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.

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.