Cohnen M, Cohnen B, Koch J A, Malms J, Teubert G, Ewen K
Institut für Diagnostische Radiologie, Heinrich-Heine-Universität, Düsseldorf.
Aktuelle Radiol. 1998 Jan;8(1):34-9.
The radiation dose at the eye lens and the thyroid gland in spiral-CT-examinations is comparable to those known from conventional computed tomography. In view of an increasing artificial radiation exposure, it remains an important aim to achieve dose reduction with persistent adequate imaging quality. We determined the doses of the named organs in four different CT-examination protocols by use of phantom studies and in 45 patients. By reduction of tube current and tube voltage, organ doses can be reduced by half. This is achieved without a relevant loss in diagnostic precision as far as high-contrast structures are concerned. Compared to conventional CT-scanning, the dose reduction reached 75%. Taking into consideration the increasing insensitivity in the z-plane and the worsening of the section-sensitivity profile, a properly chosen increase in pitch may result in a significant dose reduction. CT-scanning of high-contrast structures in the head and neck can and should be performed with the least radiation exposure possible.
螺旋CT检查中晶状体和甲状腺的辐射剂量与传统计算机断层扫描已知的剂量相当。鉴于人工辐射暴露的增加，在保持足够成像质量的同时实现剂量降低仍然是一个重要目标。我们通过体模研究和45例患者确定了四种不同CT检查方案中上述器官的剂量。通过降低管电流和管电压，器官剂量可降低一半。就高对比度结构而言，这在诊断精度上没有相关损失的情况下得以实现。与传统CT扫描相比，剂量降低了75%。考虑到z平面灵敏度的增加和断层灵敏度曲线的恶化，适当选择螺距的增加可能会导致显著的剂量降低。头部和颈部高对比度结构的CT扫描可以而且应该以尽可能低的辐射暴露进行。
