Removal of scatter radiation in paediatric cardiac catheterisation: a randomised controlled clinical trial.

OBJECTIVE: This study sought to determine if DNA integrity was compromised by ionising radiation from paediatric cardiac catheterisations and if dose optimisation techniques allowed DNA integrity to be maintained. MATERIALS AND METHODS: Children were imaged using either: (i) an anti-scatter grid (current departmental protocol), (ii) no anti-scatter grid or, (iii) no anti-scatter grid and a 15 cm air-gap between the child and the x-ray detector. Dose area product and image quality were assessed, lifetime attributable cancer risk estimates were calculated and DNA double-strand breakages quantified using the γH2AX assay. RESULTS: Consent was obtained from 70 parents/guardians/children. Image quality was sufficient for each procedure performed. Removal of the anti-scatter grid resulted in dose reductions of 20% (no anti-scatter grid) and 30% (15 cm air-gap), DNA double-strand break reductions of 30% (no anti-scatter grid) and 20% (15 cm air-gap) and a reduction of radiation-induced cancer mortality risk of up to 45%. CONCLUSION: Radiation doses received during paediatric cardiac catheterisation procedures resulted in a significant increase in DNA damage while maintaining acceptable image quality and diagnostic efficacy. It is feasible to remove the anti-scatter grid resulting in a reduction in DNA damage to the patient. The γH2AX assay may be used for assessment of dose optimisation strategies in children.

Assessment of DNA double-strand breaks induced by intravascular iodinated contrast media following in vitro irradiation and in vivo, during paediatric cardiac catheterization.

Paediatric cardiac catheterizations may result in the administration of substantial amounts of iodinated contrast media and ionizing radiation. The aim of this work was to investigate the effect of iodinated contrast media in combination with in vitro and in vivo X-ray radiation on lymphocyte DNA. Six concentrations of iodine (15, 17.5, 30, 35, 45, and 52.5 mg of iodine per mL blood) represented volumes of iodinated contrast media used in the clinical setting. Blood obtained from healthy volunteers was mixed with iodinated contrast media and exposed to radiation doses commonly used in paediatric cardiac catheterizations (0 mGy, 70 mGy, 140 mGy, 250 mGy and 450 mGy). Control samples contained no iodine. For in vivo experimentation, pre and post blood samples were collected from children undergoing cardiac catheterization, receiving iodine concentrations of up to 51 mg of iodine per mL blood and radiation doses of up to 400 mGy. Fluorescence microscopy was performed to assess γH2AX-foci induction, which corresponded to the number of DNA double-strand breaks. The presence of iodine in vitro resulted in significant increases of DNA double-strand breaks beyond that induced by radiation for ≥ 17.5 mg/mL iodine to blood. The in vivo effects of contrast media on children undergoing cardiac catheterization resulted in a 19% increase in DNA double-strand breaks in children receiving an average concentration of 19 mg/mL iodine to blood. A larger investigation is required to provide further information of the potential benefit of lowering the amount of iodinated contrast media received during X-ray radiation investigations.