螺旋CT原理,扫描参数和图像重建

螺旋ＣＴ最显著的特征是Ｘ线球管围绕病人旋转时，扫描床上病人连续通过机架，由于滑环技术的发明螺旋ＣＴ于１９８９年投入临床应用，它被广泛接受并成功地应用于人体各个部位的检查。由于产生容积数据，螺旋ＣＴ产生较少的呼吸遣漏扫描且可行允许重建，提高了Ｚ轴的分辨率。

Principles, Scan Parameters and Image Reformationsof Spiral (Helical) CT

The distinguishing characteristic of helical CT technology is thecontinuous movement of the patient on the table through the gantry as the x-raytube rotates around the patient. By inventing slip-ring gantry system, spiralcomputed tomography (CT) was introduced into clinical practice in 1989, it has gainedwidespread acceptance and has been applied successfully to all areas of the body.Because of producing a volumetric data set, helical CT results in less respiratorymisregistration and allows overlapping reconstructions, which improve the Z-axisresolution. The advantage of helical CT over single-section CT is faster acquisitionof a volumetric data set, resulting in shorter examination time. Motion andmisregistration artifacts are minimized, and high-quality reconstruction imagescan be obtaained in many instances, additional scanning after the initialacquisition is avoided by the ability to retrospectively generate overlappinginterscan images from the original data. These advantages are particularly relevantin acutely ill, multiple-trauma victims and children who require rapid and accurateimaging assessment. It has enabled new application such as CT angiography (CTA) andthree dimensional (3D) CTA.