Contribution of the fluoroscopy and cine modes to patient exposure in paediatric interventional cardiology procedures

Abstract

IntroductionPaediatric interventional cardiology procedures have grown in recent years. The main disadvantage of these procedures is the high dose of radiation that patients receive. Such methods include the fluoroscopy mode, which allows real-time visualization, and the cine mode, which allows the documentation of images. The dosimetric quantities recommended currently for these procedures are: kerma-area product (PKA), air kerma at the patient entrance reference point (Ka,r), fluoroscopy time (tFl) and number of acquired images (IN). While PKA and Ka,r characterize total irradiation during the examination, IN and tFl describe the contribution of fluoroscopy and cine modes separately. These characteristics are indirect and presume that the radiation exposure is proportional to them. Such a choice is made because most of the equipment do not supply information about the contribution of fluoroscopy and cine modes to the PKA or Ka,r separately. ObjectivesThe primary objective of this work is to evaluate the contribution of the fluoroscopy and cine modes to the total exposure; we study to what extent these contributions can be characterized by fluoroscopy and cine time and number of acquired images. We also propose local diagnostic reference levels for quantities that separately describe the contribution of fluoroscopy and cine modes. MethodsIn a period of 3 years (2019–2021), data on 135 procedures were evaluated; the study included 53% of male patients (72) and 47% of female patients (63). Cardiac catheterization procedures were considered for diagnostic (59%) and therapeutic (41%) purposes. The average weight of patients was 21.4 ± 1.7 kg (2.0–112.0 kg), and the average age was 5.3 ± 0.4 years (0.0–17.1 years). Interventional cardiology procedures were performed using a GE Innova IGS 530 equipment (GE Healthcare, Milwaukee, WI, USA), manufactured in 2016 and installed in 2017, dedicated to the paediatric population. The necessary data on each procedure was extracted from the Radiation Dose Structure Reports, generated by the equipment at the end of the procedure. This report presents the PKA values for the fluoroscopy mode and the cine mode, total PKA, the fluoroscopy time, the cine time, and IN, as well as other data related to the procedure. The diagnostic reference levels (DRLs) proposed in this study were calculated as the 3-rd quartile of the corresponding distribution. ResultsThe contribution of the cine mode to the total kerma-area product is, on average, 50% though this mode lasted about 4% of the procedure time. Only the fluoroscopy time may be used among the indirect quantities to characterize the contribution of the fluoroscopy and cine modes. ConclusionsThe following local DRLs values are proposed: 2.0 Gy⋅cm2 for kerma-area product in fluoroscopy mode, 1.9 Gy⋅cm2 for kerma-area product in cine mode and 22 min (26 min for therapeutic procedures) for fluoroscopy time. For diagnostic and therapeutic procedures, the local DRLs values may be chosen as 1.5 Gy⋅cm2 and 2.5 Gy⋅cm2 correspondingly in both modes.