Prokop M
Department of Radiology, University Medical Center Utrecht.
Radiologe. 2008 Mar;48(3):229-42. doi: 10.1007/s00117-008-1635-8.
The exponentially growing performance of newer scanner generations has increased diagnostic opportunities and utilization of computed tomography. The excellent clinical results with CT, however, have to be weighed against a high radiation exposure. While radiation exposure with modern scanners is well below the diagnostic reference values of the EU for most organ systems, radiation dose for retrospectively gated cardiac examinations can be substantially higher: organ doses can reach 100 mGy, a dose for which cancer induction been proven. For children, the situation may also be critical if scanning parameters are not adapted to their smaller size and increased radiation risk: the risk-benefit ratio may then no longer favor CT. The application of CT for young patients, patients with favorable prognosis and for frequent follow-up examinations will increase the radiation risk to the individual and the population. The growth rates for CT utilization in Germany are well below those in the United States but the increasing number of exams will lead to a substantial increase in population dose even if the dose per individual exam can be reduced. The combination of optimum scanning parameters, automated dose modulation and dose adaptation to the individual patient will help contain radiation dose. Further reduction is possible by reducing the number of scan phases, limiting the scan length and choosing a lower tube voltage. Most important, however, is the close collaboration with referring physicians: scanning technique and choice of imaging modality can only be adapted if the clinical question is clearly defined. In the light of radiation exposure the critical and knowledgeable use of CT becomes the more important the easier it is to request an exam and the better the clinical results.
新一代扫描仪性能呈指数级增长，增加了计算机断层扫描的诊断机会和使用率。然而，计算机断层扫描出色的临床效果必须与高辐射暴露相权衡。虽然对于大多数器官系统，现代扫描仪的辐射暴露远低于欧盟的诊断参考值，但回顾性门控心脏检查的辐射剂量可能会显著更高：器官剂量可达100毫戈瑞，这一剂量已被证实可诱发癌症。对于儿童，如果扫描参数未根据其较小的体型和增加的辐射风险进行调整，情况也可能很严峻：风险效益比可能不再支持使用计算机断层扫描。对年轻患者、预后良好的患者以及频繁进行随访检查的患者应用计算机断层扫描，将增加个体和人群的辐射风险。德国计算机断层扫描的使用率增长率远低于美国，但即使每次检查的剂量可以降低，检查数量的增加也将导致人群剂量大幅增加。优化扫描参数、自动剂量调制以及根据个体患者调整剂量相结合，将有助于控制辐射剂量。通过减少扫描期数限制扫描长度和选择较低的管电压，还可以进一步降低辐射剂量。然而，最重要的是与转诊医生密切合作：只有明确界定临床问题，才能调整扫描技术和成像方式的选择。鉴于辐射暴露情况，计算机断层扫描越容易被要求进行且临床效果越好，其谨慎且明智的使用就变得越重要。
