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CT scans in children can cause small but significant increases inthe risk of leukemia and brain cancer , a new study finds. Researchers say the results do not mean that CT scans should beavoided entirely they can be vitally important in certainsituations, like diagnosing severe head injuries but that thetest should be performed only when necessary, and with the lowestpossible dose of radiation. CT, or computed tomography, scans take X-rays from various anglesand combine them to create cross-sectional images, and they involvemuch more radiation than traditional X-ray techniques. Concern about potential harm from the scans has grownas their use has climbed steeply; at least four million children ayear receive scans in the United States, and researchers estimatethat a third of the scans are unnecessary or could be replaced bysafer tests like ultrasound or magnetic resonance imaging , which do not use radiation. The new study, published online on Wednesday in The Lancet, aBritish medical journal, is based on the records of nearly 180,000children who had scans from 1985 to 2002 in Britain. There were 74cases of leukemia and 135 cases of brain cancer in the group. Theauthors estimated the radiation doses and found that the more scansthe children had and the more radiation they received, the highertheir risk. Children under 15 who had two or three scans of the head had triplethe risk of brain cancer compared with the general population, theresearchers found, and 5 to 10 scans tripled the risk of leukemia.But the baseline risk is extremely low 4.5 cases of leukemia per100,000 people under 20, and 3.5 cases of cancer of the brain orcentral nervous system so that even tripled, it remains small. The basic message for childhood cancers is that they are rare, said Mark S. Pearce, the first author of the study, from NewcastleUniversity and the Royal Victoria Infirmary. In response, the American College of Radiology issued a statementurging parents not to refuse needed CT scans, especially forpotentially life-threatening conditions like head and spineinjuries, pneumonia complications and chest infections. But the organization alsolists conditions for which CT should not be the first choice; oneis suspected appendicitis in children, for which the group recommends that ultrasound beused first, followed by CT only if the ultrasound is equivocal. The Lancet study has limitations: It is observational, meaning thatthe researchers just looked at what happened to patients withoutpicking them at random to be treated or not, which provides moresolid evidence but cannot be justified ethically in studies ofradiation. In this case, all the children received scans; there isno unexposed control group. And the researchers say they do notknow why the children had the scans, though they excluded thosewhose cancer diagnosis came so soon after the CT scan that it may have been present before the scan was performed. An editorial in the same issue of the journal notes that Dr.Pearce s findings, based on data from actual patients, supportearlier risk estimates based on comparisons of the radiation dosefrom CT scans to the doses received by survivors of the atomicbombing of Japan, who had an increased risk of cancer. Theeditorial, by Dr. Andrew J. Einstein of Columbia University MedicalCenter, said that at least a dozen other research groups around theworld were studying or planning to study CT effects on children. A major study warning of CT risks to children, based on theJapanese exposure, was published in 2001; it predicted that of the600,000 children under 15 who were having head and abdominal scansin the United States each year, 500 might ultimately die of cancercaused by the CT radiation. The first author of that study, David Brenner, director of theCenter for Radiological Research at the Columbia University Collegeof Physicians and Surgeons, said that young people were often givenCT scans to diagnose kidney stones , appendicitis and dental problems, and that some of those scanscould have been avoided by using other methods, like ultrasound orconventional X-rays. There s been a lot of emphasis on reducing the dose in thedecade since, Dr. Brenner said. That s really good. Industry goton board. But, he emphasized, more work is needed to make sure doctors orderthe scans only when needed. The e-commerce company in China offers quality products such as Led Tube Light Bulbs , Ceiling Recessed Spotlights, and more. For more , please visit Decorative Ceiling Light Panels today!
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