本文主要应用电阻抗断层成像技术检测酸奶中的异物，并在异物大小、电流大小和电流频率这三个因素变化时观察其对重建图像的影响。搭建16电极数据采集系统，采用相邻法激励测量模式获得成像数据，并采用修正的牛顿-拉夫逊算法将数据进行图像重建，再采用二值化对重建图像进行后处理，最后定量分析比较成像结果坐标和面积与实际异物的偏差。实验结果表明：本方法能检测出酸奶中的塑料异物，但不能准确反映异物的位置和形状，并且对异物大小比较敏感，只能检测一定大小范围内的异物；在直径100 mm的检测域中，异物直径25 mm时检测效果最好，电流大小在15 mA时检测效果较好，电流频率在30 kHz时检测效果较好；对重建图像二值化处理, 尽管这种处理方法会丢失原有重建图像的一些细节，但是所得的图像更易观察，便于对不同条件下的成像结果进行对比。

In this study, electrical impedance tomography was used to detect a foreign body in yoghurt. It was found that variations in the size of the foreign body, applied current, and current frequency showed corresponding changes in the reconstructed image. A 16-electrode data acquisition system was established to obtain image data using an adjacent excitation/measurement scheme. The Modified Newton-Raphson algorithm was applied to reconstruct the image data, binarization was performed for post-processing of the reconstructed images, and a quantitative analysis was performed by comparing the deviations of both the coordinates and area of the images with those of the actual foreign body. The results showed that this method could detect plastic foreign objects within yoghurt, but could not determine the location and shape of the foreign body accurately. In addition, this method was sensitive to the size of the foreign body, but only within a certain range. Optimum detection was possible within a detecting region diameter of 100 mm, under the following conditions: 25 mm size of the foreign body, 15 mA current, and 30 kHz current frequency. Although some details of the original reconstructed image might be lost with this processing method, the image obtained allowed for easier observation and convenience in comparison of imaging results under different conditions.

公益性行业（农业）科研项目（201003063-07）；中央高校基本科研业务费专项基金资助项目（Z109021106，Z109021303）