Establishment of Portuguese diagnostic reference levels and trigger levels for radiation-induced tissue reactions in interventional neuroradiology

Abstract Purpose To establish national diagnostic reference levels (DRLs) for interventional neuroradiology (INR) procedures in Portugal. Methods A multicentre retrospective study was performed in six reference centres, including the six most common INR procedures: cerebral thrombectomy, cerebral arteriography, cerebral aneurysm embolisation, arteriovenous malformation (AVM) and arteriovenous fistula (AVF) embolisation, cerebral vasospasm treatment, and carotid artery stenting. Additionally, retinoblastoma embolisation, performed in a single Portuguese centre, was included. DRLs were defined as the 75th percentile (P75) of air kerma-area product (PKA, Gy·cm²), air kerma at the patient entrance reference point (Ka,r, mGy), and fluoroscopy time (FT, min). Dose variability and trigger value exceedances were analysed according to procedural complexity and pathology. Results Data of 1409 cases were analysed. The national DRLs in terms of PKA were: 109 Gy.cm² cerebral thrombectomy, 72 Gy.cm² for cerebral arteriography, 180 Gy.cm² cerebral aneurysm embolisation, 366 Gy.cm² AVM/AVF embolisation, 87 Gy.cm² cerebral vasospasm, and 74 Gy.cm² for carotid stenting. The corresponding Ka,r values were 746 mGy, 488 mGy, 2652 mGy, 4282,9 mGy, 511,0 mGy, and 520,3 mGy, and FT values were 16, 9, 39, 62, 9, 22 min, respectively. Procedural complexity factors assessed: thrombectomy attempts, aneurysm location, device selection, catheterised vessels. Retinoblastoma embolisation, demonstrated PKA 9,5 Gy.cm², Ka,r 75,7 mGy, and FT 7,1 min. Conclusions This first Portuguese INR DRL study provides preliminary national benchmarks for the most common cerebral and neck procedures. AVM/AVF embolisation showed the highest percentage of trigger value exceedances. These results will support protocol optimisation and harmonisation of radiation protection practice across centres.