Doses from ionising radiation in paediatric cardiac catheterisations in Norway 1975-2021

Paediatric patients with congenital heart disease often undergo cardiac catheterisation procedures and are exposed to considerable ionising radiation early in life. This study aimed to develop a method for estimating the dose area product (P-KA) from paediatric cardiac catheterisation procedures (1975-1989) at a national centre for paediatric cardiology and to evaluate trends in P-KA and exposure parameters until 2021. Data from 2200 catheterisation procedures on 1685 patients (1975-1989) and 4184 procedures on 2139 patients (2000-2021) under 18 years of age were retrospectively collected. P-KA values were missing for 1975-1989 but available from 2000 onward. The missing P-KA was estimated from air kerma and beam area, based on exposure records and input from clinicians working at that time. P-KA trends were analysed over time and age. There was a 71% reduction in median P-KA from the period 1975-1989 (median 6.63 Gy cm(2)) to 2011-2021 (1.91 Gy cm(2)). The P-KA increases significantly (p = 0.0001) with patient age, which was associated with body weight. Approximately 80% of the total P-KA was from cine acquisition in 1975-1989, while 20% was from fluoroscopy. The P-KA estimate during 1975-1989 was considerably impacted by the assumptions of missing parameters such as tube filtration, focus-to-heart distance, beam area, and number of cine series. The decreasing trend in P-KA values was attributed to advancements in both technologies and clinical practices. The high contribution of cine acquisition to the total dose during 1975-1989 was due to factors such as a high frame rate, multiple acquisitions, and high tube current. The estimated P-KA values for the period 1975-1989 are of importance for the dose reconstruction and risk assessments in the EU epidemiology project Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics(HARMONIC).