Radiation risks from cardiovascular imaging tests.

A 62-year-old retired account executive complains of diffuse chest pain with moderate activity. His hyper-cholesterolemia and hypertension have been well controlled. On treadmill testing , he fatigues at a heart rate of 140 bpm. You discuss the option of a pharmacological stress radionuclide study, but his reaction is concern. When questioned , he divulges that he and his wife had recently read an article in a popular lifestyle magazine that warned that " such tests cause cancer. " The concept of radiation, a physical entity that penetrates the human body yet defies perception, is emotionally laden and triggers archetypical angst in many. In recent years, a considerable number of alarmist reports have raised the specter of cancer risk from commonly prescribed imaging tests. These publications have received widespread dissemination in the lay media, often in a sensationalist manner, so medical professionals are increasingly confronted by the above patient scenario and its many variations. Public concerns have prompted the US Food and Drug Administration to devote considerable attention to radiation protection, and some states have mandated reporting of radiation doses from imaging examinations. The purposes of this Clinician Update are to summarize the evidence on stochas-tic risks from diagnostic cardiovascu-lar imaging tests involving ionizing radiation, to enable a realistic appraisal of risk, and to facilitate a rational dialog between healthcare providers and their patients. Direct evidence for an association between radiation from medical imaging and cancer induction is exceedingly scarce. The most convincing evidence is derived from 2 recent, large, epidemiological studies in young, predominantly pediatric populations. 4,5 Based on ≈10 year follow-up of 178 000 and 680 000 children and adolescents, respectively, these studies report an incremental risk of ≈2 to 6 excess cancers per 10 000 children and young adults from computed tomography (CT). Direct evidence of an association between radiation from medical imaging and cancer induction in a general adult population does not exist. Much larger cohorts would likely have to be analyzed to detect any incremen-tal increases in cancer rates because ≈38% of women and 44% of men in the United States will develop cancer during their lifetime. The overwhelming majority of recent reports on cancer risks from medical imaging are not based on actual epidemiological observations but are derived from extrapolation of risk estimates to low levels of radiation and multiplication with a large number of exposed individuals. Estimates of cancer risks from diagnostic imaging are …