The purpose of this study is to determine the average risk for thyroid irradiation for any type of paediatric cardiac catheterization, based on the cummulative at-risk dose of 100 mSv, adjusted to the measured thyroid volume and to the patient's age.

Inclusion Criteria:

• Inclusion of any patient (< 18 year-old) with congenital heart disease undergoing one or more cardiac catheterization

Exclusion Criteria:

• Exclusion of patients with any type of thyroid dissease