Automatic Identification of Relationship between Tooth Root and Mandibular Canal Based on One Step Deep Neural Network
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摘要: 为了提高曲面体层片中下颌阻生智齿牙根与下颌管位置关系的识别精度和效率,提出一种基于深度卷积神经网络的自动检测方法。该方法将下颌阻生智齿牙根与下颌管位置关系的自动检测视为回归任务与分类任务的结合,以YOLOv5网络为框架构建可同时完成分类和定位任务的深度卷积神经网络,将对应锥形束CT图像中获取的空间位置关系信息作为分类金标准,训练其学习曲面体层片图像特征与接触下颌管的智齿牙根之间的非线性关系。将新获得的曲面体层片输入到训练好的网络模型后,即可获得该曲面体层片下颌阻生智齿牙根与下颌管相互接触的概率值,同时预测出存在牙根与下颌管相互接触情况的区域。实验结果表明,本文方法能准确地判断出下颌阻生智齿牙根与下颌管是否接触,并能预测出存在牙根与下颌管相互接触情况的区域;与人工判读和其他方法相比,能获得更准确的检测结果。Abstract: To improve the accuracy and efficiency of identifying the relationship between the root of the impacted mandibular third molar (M3M) and the mandibular canal in panoramic radiographs, we proposed an automatic method based on a deep convolutional neural network. This method treats the automatic identification of the relationship between the root of the M3M and the mandibular canal as a combination of regression and classification tasks. It uses the YOLOv5 (You Only Look Once) network as a framework for constructing a deep convolutional neural network that can accomplish detection and classification tasks simultaneously. This network, which takes the spatial relationship information extracted from the corresponding cone-beam CT images as the ground-truth, was trained to learn the nonlinear relationship between image features and the root of the M3M contacting the mandibular canal. When inputting a newly acquired panoramic radiograph into the trained network, the network will output the probability value for the root of the M3M contacting the mandibular canal. In the meantime, the region that includes the root of the M3M contacting the mandibular canal can be predicted. The experimental results show that the proposed method can provide an accurate judgment of whether the roots of impacted mandibular wisdom teeth in the panoramic radiographs are in contact with the mandibular canal and the location of regions in which the roots of the M3M are in contact with the mandibular canals; compared to manual diagnosis and the other methods, the proposed method can obtain more accurate results.
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表 1 Backbone网络涉及的主要参数
Table 1. The main parameters of the backbone network
模块名称 数量 卷积核 尺寸 步长 输入尺寸 输出尺寸 Conv 1 80 3⊆3 2 608⊆608⊆3 304⊆304⊆80 Conv 1 160 3⊆3 2 304⊆304⊆80 152⊆152⊆160 CSP1_4 4 160 - - 152⊆152⊆160 152⊆152⊆160 Conv 1 320 3⊆3 2 152⊆152⊆160 76⊆76⊆320 CSP1_8 8 320 - - 76⊆76⊆320 76⊆76⊆320 Conv 1 640 3⊆3 2 76⊆76⊆320 38⊆38⊆640 CSP1_12 12 640 - - 38⊆38⊆640 38⊆38⊆640 Conv 1 1280 3⊆3 2 38⊆38⊆640 19⊆19⊆1280 CSP1_4 4 1280 - - 19⊆19⊆1280 19⊆19⊆1280 SPPF 1 1280 - - 19⊆19⊆1280 19⊆19⊆1280 表 2 本文方法与其他方法及人工判读所得预测结果对应的分类性能评价指标的对比
Table 2. The comparison of classification performance for the proposed method, manual diagnosis, and the other models
方法 准确率 灵敏度 特异度 精确度 人工判读 0.845 0.741 0.892 0.759 AlexNet 0.778 0.506 0.919 0.764 GoogLeNet 0.770 0.434 0.944 0.800 VGG-16 0.737 0.422 0.900 0.686 ResNet-50 0.831 0.663 0.919 0.809 本文方法 0.881 0.819 0.913 0.829 表 3 部分概率阈值对应的分类性能评价指标值
Table 3. The measurements of classification performance for different thresholds
概率阈值 准确率 灵敏度 特异度 精确度 0.60 0.881 0.819 0.913 0.829 0.65 0.881 0.795 0.925 0.846 0.70 0.868 0.747 0.931 0.849 0.75 0.860 0.699 0.944 0.866 表 4 使用本文方法时,不同训练迭代次数、批大小、学习率以及优化器参数对应的各分类性能指标值
Table 4. The measurements of classification performance for different iterations, epochs, learning rates, and parameters of the optimizer in the proposed method
参数名称 参数取值 准确率 灵敏度 特异度 精确度 训练迭代次数 800 0.877 0.807 0.913 0.827 1200 0.881 0.819 0.913 0.829 1600 0.835 0.614 0.95 0.864 批大小 4 0.840 0.602 0.963 0.893 6 0.881 0.819 0.913 0.829 学习率 0.0022 0.889 0.759 0.956 0.900 0.0032 0.881 0.819 0.913 0.829 0.0042 0.823 0.590 0.944 0.845 优化器参数β1(β2=0.999) 0.743 0.868 0.723 0.944 0.870 0.843 0.881 0.819 0.913 0.829 0.943 0.864 0.747 0.925 0.838 优化器参数β2(β1=0.843) 0.9 0.856 0.675 0.950 0.875 0.99 0.868 0.759 0.925 0.840 0.999 0.881 0.819 0.913 0.829 表 5 本文所用深度网络与其他模型涉及参数数量的对比
Table 5. The comparison of the number of parameters used in our network and the others
网络模型 AlexNet GoogLeNet VGG-16 ResNet-50 本文方法 参数量/M 61.0 7.0 138.4 25.5 87.3 表 6 待检测物体所在区域朝不同方向移动前和移动后,本文方法对测试图像所得预测结果的分类性能评价指标对比
Table 6. The comparison of classification performance for the predicted results between the cases with or without the regions including the targets shifted in different directions
方法 准确度 灵敏度 特异度 精确度 移动前 0.881 0.819 0.913 0.829 移动后 0.864 0.723 0.938 0.857 -
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