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背景和目的计算机断层扫描(CT)在儿科的使用增加了人们对电离辐射暴露导致癌症风险的关注。本回顾性研究的目的在于量化确定在儿科使用CT和相关辐射暴露与癌症风险联系的趋势。方法调查自1996年至2010年间15岁以下接受过CT检查的儿童,共4,857,736人年。对五家保健系统于2001年至2011年间进行的744起对头部、腹部/骨盆、胸部和脊柱的随机CT扫描进行研究后,计算辐射剂量和预估癌症风险率。上述这些部位的扫描检查数量占所有CT扫描数量的95%以上。预估的癌症终生归因风险率计算基于《电离辐射的生物学效应》(BEIR)的第七次报告———针对乳腺癌、结肠癌、肝癌、肺癌、卵巢癌、前列腺癌、胃癌、甲状腺癌、膀胱癌、子宫癌和白血病——以及使用类似方法开发出的针对口腔、食管、直肠、胰腺、肾及脑部肿瘤的计算机模型,这些肿瘤在美国所有癌症病例中所占的比例高达85%。结果在1996年至2005年间,5岁以下儿童CT检查率增加了1倍而5到14岁儿童使用率增加了2倍;2006至2007年间,儿童CT检查率保持稳定,而之后开始下降。有效剂量幅度为每次扫描0.03到69.2毫希弗。有效剂量在20毫希弗或以上的检查出现在14%~25%的腹部或盆腔扫描、6%~14%的脊柱扫描以及3%~8%的胸部扫描。与年长儿童及男性患儿相比,低龄者及女性患儿终生罹患实体癌症的风险更高;接受腹部、盆腔或脊柱CT扫描的患儿也较接受其他部位CT扫描更易引发实体癌。对于女性患儿,根据年龄不同,不同部位CT扫描辐射诱导实体癌发生情况分别为每300到390例腹部或盆腔扫描、每330到480例胸部扫描以及每270到800例脊柱扫描。对于5岁以下的患儿,进行头部CT扫描导致白血病的风险最高,达1.9/10000。美国卫生保健机构每年共对儿童各器官进行4百万次的CT扫描,这可能导致未来约4870例癌症病例。如果将最高辐射剂量降低25%,就可减少2090例癌症病例,相当于患癌风险降低43%。取消不必要的扫描,可减少3020例癌症病例,相当于患癌风险降低62%。结论CT在儿科使用的增加以及放射剂量的较大变化,导致很多儿童接受了高剂量检查。降低最高照射剂量1/4的策略可以显著地减少辐射诱发癌症的数量。
BACKGROUND & OBJECTIVE The use of computed tomography (CT) in pediatrics has raised concerns that exposure to ionizing radiation causes cancer risk. The purpose of this retrospective study was to quantify the trend of determining the association of CT exposure and associated radiation exposure with the risk of cancer in pediatric patients. Methods A total of 4,857,736 person-years of children under the age of 15 who underwent CT examination between 1996 and 2010 were surveyed. A total of 744 random CT scans of the head, abdomen / pelvis, chest and spine conducted by five health systems between 2001 and 2011 were conducted to calculate the radiation dose and to estimate the cancer risk. These sites scan the number of all CT scan number accounted for more than 95%. Estimated Lifetime Attributable Risk Rates for Cancer Calculations are based on the seventh report of the Biological Effect of Ionizing Radiation (BEIR) on breast, colon, liver, lung, ovarian, prostate, stomach, thyroid Cancer, bladder cancer, uterine cancer and leukemia - as well as computer models developed for oral, esophageal, rectal, pancreas, kidney and brain tumors using similar methods that account for up to 85% of all cancer cases in the United States %. Results Between 1996 and 2005, the rate of CT examination in children under five years old doubled and the prevalence of children aged 5 to 14 years tripled. From 2006 to 2007, the rate of CT examination in children remained stable and then decreased. The effective dose range is 0.03 to 69.2 milliwatts per scan. An effective dose of 20 mSv or above appears in 14% to 25% of abdominal or pelvic scans, 6% to 14% of spine scans and 3% to 8% of thoracic scans. Older and females have a greater risk of life-long solid cancers than older children and males, and children with CT scans of the abdomen, pelvis or spine are more likely to cause solid cancers than CT scans of other sites. For women, depending on the age, CT scanning of different parts of the body induces solid tumors to occur every 300 to 390 abdomen or pelvic scans, 330 to 480 chest scans and 270 to 800 spine scans, respectively. For children under 5 years of age, head CT scan leads to the highest risk of leukemia, 1.9 / 10000. A total of 4 million CT scans of organs in children are made annually by the U.S. health-care facilities, which could lead to about 4,870 cancer cases in the future. Reducing the maximum radiation dose by 25% will reduce 2,090 cases of cancer, which is equivalent to a 43% reduction in the risk of cancer. Canceling unnecessary scans reduced the number of cancer cases by 3,020, equivalent to a 62% reduction in the risk of cancer. Conclusion The increased use of CT in pediatrics and the large changes in radiation dose have led many children to undergo high-dose examinations. Strategies to reduce ¼ of the maximum exposure dose can significantly reduce the number of radiation-induced cancers.