Radiation Doses From X-Ray Guided Cardiac Catheterizations In Children And Young Adults In The UK

Richard HARBRON, Newcastle University, United Kingdom

1 Institute of Health and Society, Newcastle University, Newcastle-upon-Tyne, UK
2 Regional Medical Physics Department, Freeman Hospital, Newcastle-upon-Tyne NHS Foundation Trust, Newcastle-upon-Tyne, UK

Purpose: Cardiac catheterizations are x-ray guided procedures used to diagnose and treat both congenital and acquired heart conditions. The radiation doses can be relatively high, raising concerns over the increased risk of developing cancer.

Methods: A cohort of around 13,000 patients who underwent cardiac catheterizations in the UK, while aged under 22 years, was established. Individualised, examination specific dose estimates were calculated using Monte Carlo computer simulations, based on exposure indicators recorded at the time of each procedure. Cohort members were matched with the National Health Service Central Registry (NHSCR) to determine cancer incidence.

Results: 109 malignancies of all types were observed, verses 37 expected (SIR=2.94, 95% CI: 2.41, 3.56). Leukaemia (SIR=4.3, 95% CI: 2.87, 6.18), lymphoma (SIR=5.92, 95% CI: 4.04, 8.38) and cervical cancer (SIR=9.32, 95% CI: 4.55, 16.89) were also significantly raised. Half of these malignancies developed in patients who were identified as having undergone organ transplantation. Removing these patients, who made up around 5% of the cohort, reduced the SIR to 1.67 (95% CI: 1.25, 2.18). There was little suggestion of a clear relationship between cumulative radiation dose and excess risk of developing cancer. Most malignancies developed outside the thoracic region, with no cases of lung, breast, oesophageal or stomach cancer being identified. Considering only cases developing 5 years (solid cancers) or 2 years (leukaemia ) following the first recorded exposure, the SIR was reduced to 2.13 [95% CI: 1.48, 2.97].

Conclusions: Children and young adults undergoing cardiac catheterizations appear to have a significantly higher incidence of cancer than the general population. This appears to be mainly due to factors other than radiation. The impact of transplantation on risk must be taken into account in medical radiation epidemiological studies. Further studies following enlargement of the cohort will follow.

Funding source: British Heart Foundation