Risks of cardiac imaging
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* David A. Toms

With regard to the research article by Eisenberg and colleagues,1 the authors only briefly note that the radiation-associated increase in cancer risk is higher than for atomic bomb survivors in the Life Span Study (LSS).2 In the LSS, the excess relative risk per sievert (Sv) for the group exposed at 40 years or older is about 0.25, which would correspond with a 0.25% increase in cancer risk per 10 mSv;2 the *CMAJ* publication finds a 3% increased risk per 10 mSv for patients exposed at a similar age. The LSS data given are for cancer mortality whereas the current study is for cancer incidence, but effects of radiation on cancer incidence are only slightly higher than those for cancer mortality.3 Could the authors comment in more detail?

## References

1.  Eisenberg MJ, Afilalo J, Lawler PR, et al. Cancer risk related to low-dose ionizing radiation from cardiac imaging in patients after acute myocardial infarction. CMAJ 2011;183:430-6.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czo5OiIxODMvNC80MzAiO3M6NDoiYXRvbSI7czoyNDoiL2NtYWovMTgzLzE2LzE4ODUuMS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

2.  National Research Council of the National Academies, Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation. Biological effects of ionizing radiation — BEIR VII phase 2. Washington (DC): National Academies Press; 2006. p. 146.
    
    

3.  National Research Council of the National Academies, Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation. Biological effects of ionizing radiation — BEIR VII phase 2. Washington (DC): National Academies Press; 2006. p. 144-5.