| 高燕莉,翟仁友,张镭,李剑颖.64排CT容积HRCT扫描方案优化的模具研究[J].中国医学影像技术,2008,24(4):614~617 |
| 64排CT容积HRCT扫描方案优化的模具研究 |
| Optimization of volumetric high-resolution CT protocols with 64-detector CT: a phantom study |
| 投稿时间：2007-10-26 修订日期：2008-02-28 |
| DOI： |
| 中文关键词: 体层摄影术,X线计算机 体模,显像术 |
| 英文关键词:Tomography, X-ray computed Phantoms, imaging |
| 基金项目: |
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| 摘要点击次数: 2270 |
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| 中文摘要: |
| 目的 优化容积HRCT的扫描方案,提高容积HRCT的图像质量。方法 应用64排CT对Catphan模具进行扫描,采用螺旋扫描方式,对HRCT的扫描方案进行优化,优化的参数包括:探测器宽度、焦点尺寸、旋转时间、管电压及管电流、扫描孔径、螺距、重建卷积函数、重建模式。结果 增加探测器宽度可使噪声降低(t=-4.228, P=0.002),放射剂量降低,对空间分辨率无明显影响。改变旋转时间对空间分辨率、噪声(F=0.627, P=0.130)均无明显差异。小焦点较大焦点的空间分辨率提高1 LP/cm。增加管电压与管电流可使噪声降低,空间分辨率随之改善,放射剂量增加。不同扫描孔径的放射剂量有所不同。螺距0.5得到最佳的Z轴分辨率12 LP/cm。在3种高分辨率算法中,bone优于 bone plus及edge。重建模式plus较full的噪声降低(t=58.234, P<0.001),Z轴分辨率也降低。结论 采用优化的扫描方案,可以提高容积HRCT的图像质量并控制放射剂量,有助于正确评价容积HRCT的价值。 |
| 英文摘要: |
| Objective To optimize the protocols of volumetric high-resolution (VHRCT) scanning with 64-detector CT and improve the image quality of VHRCT. Methods Catphan phantom scans on GE LightSpeed VCT were used to optimize the protocols for HRCT application with helical scan modes. Optimum protocols were selected by changing 9 sets of parameters systematically. These parameters included scan coverage, focal spot size, kV, mA, rotation time, scan field-of-view (SFOV), pitch, reconstruction kernel, reconstruction mode (plus or full). Image slice thickness was 0.625 mm. The phantom was scanned for 2 times under each set of parameters. The spatial-resolution (line-pair/cm), noise (standard deviation in an ROI) and radiation dose (CTDI) were measured for each CT scan. Results When scan coverage increased, noise (t=-4.228, P=0.002) and dose reduced without lowering spatial-resolution. The spatial-resolution increased 1 line-pair/cm when changing from large to small focal spot. Different rotation time had no effect on spatial-resolution, noise (F=0.627, P=0.130) and dose. When SFOV changed from large to small bowtie, dose was reduced without affecting the spatial-resolution and noise. The best Z-axis resolution (12 line-pairs/cm) was obtained with pitch 0.5 and full reconstruction mode. Comparing the 3 high-resolution algorithms, bone kernel was superior to bone plus and edge. Noise was reduced when changing the reconstruction mode from full to plus (t=58.234, P<0.001). Conclusion Using the optimized protocol can improve image quality and control radiation dose. |
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