Cumulative Diagnostic Radiation Associated with Leukemia, Brain Tumors among Children

Use of computed tomography (CT) scans in children and young adults resulting in cumulative doses of about 50 mGy might almost triple the risk of leukemia and doses of about 60 mGy might triple the risk of brain cancer, according to the results of a study published online June 7, 2012, in theLancet. The study included patients without previous cancer diagnoses who were first examined with CT in National Health Service centers in Great Britain between 1985 and 2002, when they were younger than 22 years of age. When compared with patients who received a dose of less than 5 mGy, the data indicated that the relative risk of leukemia was increased for patients who received a cumulative dose of at least 30 mGy and the relative risk of brain cancer was increased for patients who received a cumulative dose of 50 to74 mGy. The researchers mention that because these cancers are relatively rare, the cumulative absolute risks are small, noting that in the 10 years after the first scan for patients younger than 10 years, one excess case of leukemia and one excess case of brain tumor per 10,000 head CT scans were estimated to occur. Although potential clinical benefits should outweigh the small absolute risks, they recommend that radiation doses from CT scans should be kept as low as possible and alternative procedures that do not involve ionizing radiation should be considered when appropriate.