gamma-H2AX foci as a biomarker for patient X-ray exposure in pediatric cardiac catheterization: are we underestimating radiation risks?

Circulation. 2009 Nov 10;120(19):1903-9. doi: 10.1161/CIRCULATIONAHA.109.880385. Epub 2009 Oct 26.


Background: A better knowledge of patient x-ray dose and the associated radiation risk in pediatric interventional cardiology is warranted in view of the extensive use of x-rays and the higher radiosensitivity of children. In the present study, gamma-H2AX foci were used as a biomarker for radiation-induced effects. Patient-specific dose was assessed and radiation risks were estimated according to the linear-no-threshold model, commonly used in radiation protection, and the gamma-H2AX foci data.

Methods and results: In 49 pediatric patients (median age, 0.75 years) with congenital heart disease who underwent cardiac catheterization procedures, blood samples were taken before and shortly after the procedure. gamma-H2AX foci were determined in peripheral blood T lymphocytes. In each patient, a net increase in gamma-H2AX foci, representing DNA double-strand breaks induced by interventional x-rays, was observed. In addition, a patient-specific Monte Carlo simulation of the procedure was performed, resulting in individual blood, organ, and tissue doses. Plotting of gamma-H2AX foci versus blood dose indicated a low-dose hypersensitivity. Median effective doses calculated according to the International Commission on Radiological Protection 60 and 103 publications are 5.6 and 6.4 mSv, respectively. The lifetime-attributable risk of cancer mortality was calculated from the linear-no-threshold model and the gamma-H2AX foci data. This resulted in lifetime-attributable risk values of 1% and 4%, respectively, for the patient population under study.

Conclusions: gamma-H2AX foci as a biomarker for DNA damage indicate that radiation risk estimates according to the linear-no-threshold hypothesis are possibly underestimates. Great care should be taken to minimize and optimize patient radiation exposure.

MeSH terms

  • Biomarkers / blood
  • Cardiac Catheterization / adverse effects*
  • Cardiac Catheterization / mortality
  • Child
  • Child, Preschool
  • Computer Simulation
  • DNA Damage
  • Female
  • Heart Defects, Congenital / diagnostic imaging*
  • Heart Defects, Congenital / mortality*
  • Histones / blood*
  • Humans
  • Incidence
  • Infant
  • Infant, Newborn
  • Male
  • Monte Carlo Method
  • Neoplasms / mortality
  • Radiation Dosage
  • Radiation Injuries / blood*
  • Radiation Injuries / mortality*
  • Radiography
  • Risk Assessment
  • Risk Factors


  • Biomarkers
  • H2AX protein, human
  • Histones