64 层螺旋CT 的层敏感度曲线测试

64 层螺旋CT 的层敏感度曲线测试
刘传亚 秦维昌 王巍 卢传友
【摘要】 目的 测试和评价64 层螺旋CT 的层敏感度曲线( SSP) 及有效层厚半高宽( FWHM) 。
方法 对Somatom Sensation 64 层螺旋CT, 使用临床常用的腹部螺旋扫描模式和CT 质控delta ( δ) 体
模, 分别以螺距( pitch) = 0. 50、0. 75、1. 00、1. 25、1. 50, 重建层厚0. 6 mm( 标称值) 进行扫描和重建。
对于pitch = 1. 00, 再分别以层厚1. 0、1. 5 mm 进行重建。然后测试各种情况的SSP 和有效层厚。
结果 对于标称层厚0. 6 mm, 不同pitch 时测试的有效层厚分别为0. 67、0. 67、0. 66、0. 69、0. 69 mm;
pitch = 1. 00 时, 标称层厚0. 6、1. 0、1. 5 mm 的有效层厚分别为0. 66、1. 06、1. 52 mm。有效层厚均略
大于标称层厚, 但与标称层厚相比均不超过0. 1 mm。测试的SSP 形状近似钟形, 左右分布基本对称,
没有延伸较长的尾部; 随着重组层厚的增加, SSP 逐渐变平阔; 当pitch 改变时, SSP 变化轻微。结论
对于Sensation 64 层螺旋CT, pitch 的变化对SSP、有效层厚和z 轴空间分辨率的影响很小。这一结论
有助于临床应用中优化CT 扫描方案。
【关键词】 体层摄影术, X 线计算机; 评价研究
Measurement of slice sensitivit y pr ofile for a 64-slice spir al CT system LIU Chuan-ya * , QIN Weicha
ng, WANG Wei, LU Chuan-you. * Shandong Provincial Medical Ima ging Research Institute, J inan
250021, China
Corresponding author: QIN Wei-chang, Email: qin_wch@sina. com
【Abstra ct 】 Object ive To measure and evaluate slice sensitivity profile ( SSP) and the full width at
half-maximum( FWHM) for a 64-slice spiral CT system. Methods Using the same CT technique and body
mode as those used for clinical CT, delta phantom was scanned with Somatom Sensation 64-slice spiral CT.
SSPs and FWHM were measured both with reconstruction slice width of 0. 6 mm at pitch = 0. 50, 0. 75,
1. 00, 1. 25, 1. 50 and with reconstruction slice width of 0. 6, 1. 0, 1. 5 mm at pitch = 1 respectively.
Results For normal slice width of 0. 6 mm, the measured FWHM, i. e. effective slice width, is 0. 67,
0. 67, 0. 66, 0. 69, 0. 69 mm at different pitch. All the measured FWHM deviate less than 0. 1mm from the
nominal slice width. The measured SSPs are symmetrical, bell-shaped curves without far-reaching tails, and
show only slight variations as a function of the spiral pitch. When reconstruction slice width increase,
relative SSP become wider. Conclusions The variation of pitch hardly has effect all on SSP, effective slice
width, and z-direction spatial resolution for Sensation 64-slice spiral CT system, which is helpful to optimize
CT scanning protocol.
【Key wor ds】 Tomography, X-ray computed; Evaluation study

64 层螺旋CT 的层敏感度曲线测试--普通.rar