Doses from ionizing radiation in pediatric cardiac catheterizations 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 cm²) to 2011–2021 (1.91 Gy cm²). 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).