Radiation Exposure from Medical Imaging: are Doses in the Carcinogenic Range?

描述（由申请人提供）：在过去十年中，医学成像的使用急剧增加，特别是计算机断层扫描（CT）成像。将CT纳入日常护理对患者的健康产生了极其积极的影响，CT的发展被广泛认为是医学上最重要的进步之一。然而，与CT相关的辐射剂量是巨大的。例如，胸部CT的辐射剂量是常规胸部x光的50-500倍。因此，随着CT利用率的提高，医疗电离辐射暴露也明显增加。广泛的流行病学证据表明，电离辐射照射与辐射诱发癌症的发生有关，特别是对辐射敏感的器官，如甲状腺、乳房和造血系统。对个体患者的风险可能相对较小；但许多人每年都受到辐射，由于成像技术的进步和多阶段研究的使用，每次检查的辐射量越来越大。这可能会导致许多癌症病例直接由与成像相关的辐射引起。此外，反复接受医学影像学检查的患者和接受任何影像学检查的儿童可能面临特别高的风险。重要的是要了解通过医学成像传递的辐射，因此可以权衡成像的潜在危害和它的好处。关于目前美国医疗辐射暴露的数据很少。了解医疗辐射暴露是制定合理策略以尽量减少不必要暴露的关键第一步。拟议研究的目的是确定涉及电离辐射暴露的诊断性医学成像的使用模式；定量估计与医学成像有关的电离辐射年平均照射量，并确定与接受特别高剂量辐射有关的病人和医生因素。为了实现这些目标，我们将对在华盛顿州西雅图的一个大型、混合模式、非营利性医疗保健系统Group Health注册的患者进行回顾性队列分析，该系统的50万名成员在1993年至2007年间接受了大约650万次影像学检查。团体健康收集和存储自动化数据，包括详细的临床记录，以及所有专业医生进行的所有放射成像的指征和结果。利用这个庞大的、以人口为基础的数据库，我们将描述随时间推移的诊断成像模式，估计与成像相关的辐射剂量的时间趋势，并确定与医学成像辐射暴露最高相关的因素。完成这些目标将提供与医学成像有关的辐射问题严重程度的定量数据。此外，如果我们验证了群体健康数据可以用于此类研究，那么未来的研究将使用群体健康数据来评估与电离辐射相关的癌症的相对风险。这项研究的最终目标是帮助将医疗暴露于电离辐射的程度降到最低。公共卫生相关性：在过去十年中，医学成像的使用急剧增加，特别是计算机断层扫描（CT）成像，最初称为计算机轴向断层扫描（CAT）扫描。将CT纳入日常护理改善了患者的健康状况，CT的发展被广泛认为是医学上最重要的进步之一。然而，大量的辐射剂量与CT有关。例如，胸部CT的辐射剂量是常规胸部x光的50-500倍。因此，随着CT使用的增加，电离辐射的医疗暴露也显著增加。许多流行病学证据表明，电离辐射暴露与辐射诱发癌症的发生有关。关于目前美国医疗辐射暴露的数据很少。了解医疗辐射暴露是制定合理策略以减少不必要暴露的关键第一步。拟议研究的目的是确定涉及电离辐射暴露的诊断性医学成像的使用模式；估计与医学成像有关的电离辐射年平均暴露量；并确定与接受高剂量辐射有关的病人和医生因素。随后的研究将量化接受医学成像特别高剂量辐射的个体患癌症的相对风险增加。完成提出的目标将有助于测量与医学成像相关的辐射问题。这项研究的最终目的是帮助将医疗暴露于电离辐射的程度降到最低。

DESCRIPTION (provided by applicant): The use of medical imaging has increased dramatically over the last decade, particularly imaging with computed tomography (CT). Integrating CT into routine care has had an extremely positive impact on patient health, and the development of CT is widely considered one of the most important advances in medicine. However, the radiation doses associated with CT are substantial. For example, a chest CT can deliver 50-500 times the radiation dose of a routine chest x-ray. Therefore, along with the increased utilization of CT has come a marked increase in the medical exposure to ionizing radiation. Extensive epidemiological evidence has linked exposure to ionizing radiation with development of radiation-induced cancers, particularly to radiation-sensitive organs, e.g., the thyroid, breast, and hematopoetic systems. The risk to an individual patient is probably relatively small; but many people are exposed annually, with increasingly large exposures per examination from technological advances in imaging and the use of multiple-phase studies. This could translate into many cancer cases resulting directly from the radiation associated with imaging. Additionally, patients who undergo repeated medical imaging, and children who undergo any imaging, may be at particularly high risk. It is important to understand the radiation delivered through medical imaging, so this potential harm of imaging can be weighed against its benefits. Few data are available regarding current exposure to medical radiation in the United States. Understanding exposures to medical radiation is a crucial first step to develop reasonable strategies to minimize unnecessary exposure. The aims of the proposed study are to identify patterns in the utilization of diagnostic medical imaging that involves exposure to ionizing radiation; to quantitatively estimate average annual exposures to ionizing radiation associated with medical imaging and to identify patient and physician factors that are associated with the receipt of particularly high doses of radiation. To pursue these aims, we will conduct a retrospective cohort analysis of patients enrolled in Group Health, a large, mixed-model, nonprofit, healthcare system in Seattle, WA, whose 500,000 members underwent approximately 6.5 million imaging tests between 1993 and 2007. Group Health collects and stores automated data, including detailed clinical records, and the indication and result of all radiological imaging, conducted by physicians of all specialties. Using this large, population-based database, we will describe patterns of diagnostic imaging over time, estimate temporal trends in radiation doses associated with imaging, and determine factors associated with having the highest exposure to medical imaging radiation. Completing these aims will provide quantitative data on the magnitude of the problem of radiation associated with medical imaging. Further, if we validate that Group Health data can be used for such research, future studies will use Group Health data to evaluate the relative risk of cancer associated with ionizing radiation. The ultimate goal of this research is to help keep medical exposure to ionizing radiation to a minimum. PUBLIC HEALTH RELEVANCE: The use of medical imaging has increased dramatically over the last decade, particularly imaging with computed tomography (CT), originally called computerized axial tomography (CAT) scans. Integrating CT into routine care has improved patient health and the development of CT is widely considered one of the most important advances in medicine. However, substantial radiation doses are associated with CT. For example, a chest CT can deliver 50-500 times the radiation dose of a routine chest x-ray. So along with the increased use of CT has come a marked increase in the medical exposure to ionizing radiation. Much epidemiological evidence has linked exposure to ionizing radiation with development of radiation-induced cancers. Little data are available about current exposure to medical radiation in the United States. Understanding exposures to medical radiation is a crucial first step toward developing reasonable strategies to minimize unnecessary exposure. The aims of the proposed study are to identify patterns in the use of diagnostic medical imaging that involves exposure to ionizing radiation; to estimate average annual exposures to ionizing radiation associated with medical imaging; and to identify patient and physician factors associated with receiving particularly high doses of radiation. Subsequent research will quantify the increased relative risk of developing cancer among individuals who have received particularly high doses of radiation from medical imaging. Completing the proposed aims will help measure the problem of radiation associated with medical imaging. The ultimate goal of this research is to help keep medical exposure to ionizing radiation to a minimum. .