Establishment of local diagnostic reference levels for radiation dose in paediatric interventional cardiology procedures in Brazil

Diagnostic and therapeutic interventional cardiology procedures are essential tools for evaluating congenital pathologies in paediatric patients. However, these procedures may expose patients to high levels of ionizing radiation. In this paper, we present the results of the radiation doses received by patients undergoing interventional cardiac procedures at a paediatric hospital in Brazil, aiming to establish local Diagnostic Reference Levels (DRL). The data were collected over a period of three years (2019-2022), and 148 procedures were analyzed, comprising 53% male (78) and 47% female (70) patients. These procedures included both diagnostic (59%) and therapeutic (41%) cardiac catheterization interventions. The average patient weight was 21.4 +/- 1.7 kg (2.0-112.0 kg), with an average age of 5.3 +/- 0.4 years (0.0-17.1 years). Comprehensive data for each procedure were extracted from Radiation Dose Structure Reports generated by the equipment. The results showed significant differences between diagnostic and therapeutic procedures, and the DRL values were estimated considering the age and weight of the patients. The DRL values correspond to the 3rd quartile of the dose distribution for each group. The following local DRL values were estimated, considering the patient's ages. For diagnostic procedures, the P-KA defined according to the age groups <1, 1-5, 5-10, 10-15, and >15 years were respectively: 1.4, 2.8, 3.1, 4.3 and 12.0 Gy cm(2). For therapeutic procedures, the DRL values for patients with the same ages were: 2.0, 3.7, 5.4, 7.4, and 30.9 Gy cm(2). For the total procedures, the P-KA values were 1.7, 3.2, 4.9, 6.6, and 24.5 Gy cm(2), respectively. The suggested local DRL values for weight groups (<5, 5-15, 15-30, 30-50, and 50-80 kg) for P-KA in diagnostic procedures were: 1.3, 2.2, 3.2, 4.1, and 7.9 Gy cm(2), respectively. For therapeutic procedures, the P-KA values were 1.1, 2.7, 5.4, 5.5, and 30.9 Gy cm(2), respectively. For the total procedures, the P-KA values were 1.25, 2.5, 4.6, 4.2, and 18.3 Gy cm(2), respectively. For establishing P-KA DRL, patient weight was found to be preferable over age, whereas for K-a,K-r, both approaches yielded nearly identical results.