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Researchers at the University of California, Berkeley’s School of Public Health have found that children with acute lymphoid leukaemia (ALL) had nearly twice the chance of having been exposed to three or more x-rays, compared with children who did not have leukaemia. The results differed depending on the area of the body that had been imaged, with a small increase associated with those who had had chest x-rays, and for B-cell ALL just one x-ray was enough to slightly increase the risk. The study covered 827 children with leukaemia up to age 15 who were all matched by age, gender and ethnicity and maternal race with other children from the Californian Birth Registry. Mothers of the children were interviewed within four months of diagnosis. Data collected included the number of x-rays their child had in the 12 months or longer prior to diagnosis, as well as the number of x-rays the mother had during her pregnancy or in the year preceding her pregnancy. Dental x-rays were not included as they are thought to be too low-radiation dose and too common to count. The results found that there was an increased risk from x-rays for ALL but not AML or T-cell leukaemia. There was no increased risk associated with pre-natal or maternal x-rays, which were uncommon among the study population, and there was no increased risk associated with the child’s age at first x-ray. "X-rays are a valuable tool, and our findings indicate that their use should continue to be judicious," said Karen Bartley, doctoral student in epidemiology and first author of the study. "Of greater concern, perhaps, is the use of newer imaging technologies, which are becoming more common and which produce far higher doses of radiation." A 2009 study from the National Cancer Institute projected that the 72 million computed tomography (CT) scans taken in 2007 (in America) would lead to 29,000 excess cancers. (This report is on our site, so I’ll put link to it…) Some CT scans can generate 500 times the radiation of a plain film x-ray. UC San Francisco radiologist Dr. Rebecca Smith-Bindman, who was not involved in this study says, "The bottom line is we have to be very cautious about the use of any medical imaging techniques. They can be enormously helpful for making accurate diagnoses, but tests that deliver ionizing radiation are associated with small – but real – risks of future complications related to the radiation exposure, and thus they should be used judiciously." 10/10
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