Edge artifact correction for industrial computed tomography images
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摘要: 为了去除工业CT图像中的边缘伪影,提高CT图像的识别能力和尺寸测量精度,提出一种降低串扰的系数修正法。首先分析得出边缘伪影主要是由散射射线在相邻探测通道之间的串扰所导致,并给出了探测通道串扰的数学模型;然后根据数学模型设计实验方案,通过对影响串扰率的主要因素进行实验分析,得到串扰率随入射X射线能量和被测物体厚度变化关系,再通过最小二乘拟合得出投影数据关于串扰率的函数;最后利用此函数对投影数据进行校正,降低了串扰的影响。实验结果表明,探测器间一级串扰率约为9.0%,二级串扰率约为1.2%,其中一级串扰是造成边缘伪影的主要因素,采用本文方法能够有效地抑制边缘伪影,同时较好地保留了图像细节和边缘。Abstract: To eliminate the edge artifacts of industrial CT images, and improve the identification ability of the image and the precision of the dimension measurement, a coefficient adjusting method for reducing crosstalk noise is proposed. It is concluded from theoretical analysis that crosstalk generated from adjacent detectors by Compton scattering is the major reason for the edge artifacts. According to the mathematic model of the detector crosstalk, we design a special detector system configuration and stair-step phantom for estimating the quantity of crosstalk noise. The relationship between crosstalk ratio and intensity of the incident X-ray is acquired by regressing experimental data with least square method. The experimental result shows that the first-order crosstalk ratio between detectors is about 9.0%, and the second-order crosstalk ratio is about 1.2%. Thus the first-order crosstalk is the main factor causing edge artifacts. The proposed method can reduce the edge artifacts significantly, and meanwhile maintain the detail and edge of CT images.
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Key words:
- industrial computed tomography /
- edge artifacts /
- Compton scattering /
- crosstalk /
- crosstalk ratio /
- detector module
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