CT of the chest: minimal tube current required for good image quality with the least radiation dose.
CT of the chest: minimal tube current required for good image quality with the least radiation dose.
复制标题
胸部CT：以最小的管电流以最少的辐射剂量获得良好的图像质量。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
N. Müller
中科院分区：
文献类型：
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作者：
J. Mayo;T. Hartman;K. Lee;S. Primack;S. Vedal;N. Müller
目的
我们想确定在常规10 mm准直胸部CT上保持良好图像质量所需的最小管电流（mAs），以及管电流降低对纵隔和肺部异常检测的影响。希望降低管电流以降低患者辐射剂量。
受试者和方法
首先，连续30例年龄大于45岁的患者（平均体重68 kg;范围34-93 kg）采用标准技术（120 kVp，400 mAs）进行常规胸部CT，在两个水平（气管隆突和左心房）的降低管电流（200、140、80、20 mAs）下额外成像4个切片。CT扫描由两名对所用技术因素不知情的独立观察者以随机顺序进行评价。主观图像质量按5分量表从非诊断性到极好进行分级。评估了纵隔淋巴结病（n = 18）、胸膜斑（n = 17）、积液（n = 28）、肺实质结节（n = 37）和肺气肿（n = 15）的可视化。将400 mAs扫描视为参考标准。
结果
与参考技术（400 mAs）相比，第一和第二（200 mAs和140 mAs）降低水平在主观图像质量方面没有显著差异（p > 0.05）。在第三和第四（80 mAs和20 mAs）降低水平下观察到显著差异（p <0.001）。然而，不同的管电流在纵隔或肺实质异常的检测中没有显著差异（p > 0.05）。
结论
管电流（400-140 mAs）和由此产生的辐射剂量的两倍降低不会导致主观图像质量或常规胸部CT纵隔或肺部异常检测的显著变化。140毫安-秒是为平均体重的患者提供良好图像质量所需的最小管电流。
OBJECTIVE
We wanted to determine minimal tube current (mAs) required for consistently good image quality on conventional 10-mm collimation chest CT and effect of tube current reduction on detection of mediastinal and lung abnormalities. Tube current reduction is desirable to reduce patient radiation dose.
SUBJECTS AND METHODS
Prospectively, 30 consecutive patients (mean weight, 68 kg; range, 34-93 kg) older than 45 undergoing conventional chest CT with standard technique (120 kVp, 400 mAs) had four additional sections imaged at reduced tube current (200, 140, 80, 20 mAs) at two levels (tracheal carina and left atrium). CT scans were evaluated in random order by two independent observers who were blinded to technical factors used. Subjective image quality was graded on a five-point scale from non-diagnostic to excellent. Visualization of mediastinal adenopathy (n = 18), pleural plaques (n = 17), effusions (n = 28), lung parenchymal nodules (n = 37), and emphysema (n = 15) were assessed. The 400 mAs scan was considered the reference standard.
RESULTS
When compared with the reference technique (400 mAs), the first and second (200 mAs and 140 mAs) reduction levels showed no significant difference (p > .05) in subjective image quality. A significant difference (p < .001) was seen at the third and fourth (80 mAs and 20 mAs) reduction levels. However, no significant difference (p > .05) was seen in detection of mediastinal or lung parenchymal abnormalities with different tube currents.
CONCLUSION
A twofold reduction in tube current (400-140 mAs) and resultant radiation dose did not cause a significant change in subjective image quality or in detection of mediastinal or lung abnormalities with conventional chest CT. One hundred forty milliampere-seconds is the minimal tube current required to provide good image quality in patients of average weight.