Pupil Ultrasound Images Segmentation and Diameter Measurements Based on Improved Graph Cuts
1 Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou 310027, China
2 Emergency Department of Second Affiliated Hospital of Zhejiang University, Hangzhou 310027, China
Abstract:The traditional measurement of pupil diameter is manually measured, but for patients who have ocular trauma or loss of consciousness this method is inconvenience. Aiming to solve the problem of large manual interaction in pupil diameter measurement and the weak measuring robustness, we used improved graph cut segmentation algorithm to segment pupil ultrasound images and measure pupil diameters. In this paper, we improved the traditional graph cut algorithm in two aspects. One is using adaptive threshold region growing to take place of manually seeds selection, which ensures the segmentation results while reducing the amount of manual interaction. The other one is increasing gradient information of the image into data entry portion of the energy function, which reduces the small area in the segmentation results and enhances the weak edges of segmentation. The proposed method realized automatic segmentation of image and automatic measurement of the pupil diameter. By employing the method we acquired dynamic changes of patient pupil diameter and provide a basis for clinical diagnosis. To verify the validity of the algorithm, we used the method to measure the diameter of ten patients’ dynamic pupil ultrasound images, and compared the results with that obtained by manual measurements. It is shown that the absolute error is less than 0.2 mm, the correlation coefficient is at least 0.83. In conclusion, the modified graphcut algorithm improved segmentation results, achieved automatical measurements of pupil diameters using dynamic ultrasound pupil images, and can be expected to substitute manual measurements and reduce the amount of human interaction.
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