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 inP_KAand 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_KAvalues were missing for 1975-1989 but available from 2000 onward. The missingP_KAwas estimated from air kerma and beam area, based on exposure records and input from clinicians working at that time.P_KAtrends were analysed over time and age. There was a 71% reduction in medianP_KAfrom the period 1975-1989 (median 6.63 Gy cm²) to 2011-2021 (1.91 Gy cm²). TheP_KAincreases significantly (p= 0.0001) with patient age, which was associated with body weight. Approximately 80% of the totalP_KAwas from cine acquisition in 1975-1989, while 20% was from fluoroscopy. TheP_KAestimate 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 inP_KAvalues 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 estimatedP_KAvalues 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).