Cumulative radiation exposure and cancer risk estimation in children with heart disease

Abstract

Background: Children with heart disease are frequently exposed to imaging examinations that use ionizing radiation. Although radiation exposure is potentially carcinogenic, there are limited data on cumulative exposure and the associated cancer risk. We evaluated the cumulative effective dose of radiation from all radiation examinations to estimate the lifetime attributable risk of cancer in children with heart disease.

Methods and results: Children ≤6 years of age who had previously undergone 1 of 7 primary surgical procedures for heart disease at a single institution between 2005 and 2010 were eligible for the study. Exposure to radiation-producing examinations was tabulated, and cumulative effective dose was calculated in millisieverts. These data were used to estimate lifetime attributable risk of cancer above baseline using the approach of the Committee on Biological Effects of Ionizing Radiation VII. The cohort included 337 children exposed to 13 932 radiation examinations. Conventional radiographs represented 92% of examinations, whereas cardiac catheterization and computed tomography accounted for 81% of cumulative exposure. Overall median cumulative effective dose was 2.7 mSv (range, 0.1-76.9 mSv), and the associated lifetime attributable risk of cancer was 0.07% (range, 0.001%-6.5%). Median lifetime attributable risk of cancer ranged widely depending on surgical complexity (0.006%-1.6% for the 7 surgical cohorts) and was twice as high in females per unit exposure (0.04% versus 0.02% per 1-mSv effective dose for females versus males, respectively; P<0.001).

Conclusions: Overall radiation exposures in children with heart disease are relatively low; however, select cohorts receive significant exposure. Cancer risk estimation highlights the need to limit radiation dose, particularly for high-exposure modalities.

Keywords: catheterization; imaging; pediatrics; radiography.

Figure 1

Percentage contribution of each imaging modality to number of examinations performed and cumulative effective dose. Cath = catheterization; CT = computed tomography; fluoro = fluoroscopy.

Figure 2

The lifetime attributable risk of cancer above baseline for specific radiation-producing examinations. The lifetime attributable risk of cancer was calculated using median measured exposure for all cardiac catheterization procedures and estimated exposure based on previously published data for all other radiation-producing examinations.^{Appendix 1} The lower and upper limits are based on the BEIR VII confidence intervals. A lower and upper limit estimate was calculated for each examination on each patient, and the data presented represent the median cohort values for these limits. CT = computed tomography; GI = gastrointestinal; KUB = kidneys ureters bladder; AP = anteroposterior; PA = posteroanterior.