基于CT成像过程的数学模型的参数拟合法气道测量的研究

发布时间：2018-04-13 01:23

本文选题：慢性阻塞性肺疾病 + 气道测量　；参考：《中南大学》2012年硕士论文

【摘要】：慢性阻塞性肺疾病COPD是一种严重危害人类健康的疾病。基于二维CT图像的胸腔内气道高精度几何测量对COPD患者的诊断和治疗具有重要意义。半高宽法是目前通用的气道几何尺寸测量法,但该方法只在测量大、厚且垂直CT成像平面的气道时才能获得较理想的效果,并不适用于所有尺寸气道的测量。为改善小气道的几何测量精度,本文采用一种基于CT成像过程的数学模型的参数拟合法。该方法首先利用Bresenham算法检查穿过气道壁射线的灰度值,得到射线的真实灰度轮廓；然后构建模拟CT模糊的数学模型；最后通过Levenberg-Marquardt算法对模拟灰度轮廓和真实灰度轮廓进行拟合,从而得到最接近于真实灰度轮廓的模型参数估计—气道的内、外径估计。本文方法对CT成像过程中引入的模糊进行了建模,适用于不同尺寸气道的几何测量。为了验证本文方法的有效性,利用蒙特卡洛投影仿真工具包(V4r2.3.2)对7个不同管径的二维理想环状气道模型进行仿真,然后分别使用半高宽法和本文方法来测量仿真图形。结果表明,在测量小、薄壁气道模型时,本文方法具有较高的测量精度和稳定性。将两种方法分别应用于15例COPD患者RB1吸气相3-5级气道胸部CT图像的气道测量实验。结果表明,两种方法测量结果的差异主要存在于5级气道的测量中,且本文方法能得到比半高宽法更稳定的测量结果。
[Abstract]:Chronic obstructive pulmonary disease (COPD) is a serious disease that endangers human health.High precision geometry measurement of thoracic airway based on two-dimensional CT images is of great significance for the diagnosis and treatment of COPD patients.Half-height width method is a universal method for measuring the geometry of airways. However, the method can only obtain ideal results when measuring the airways with large, thick and vertical CT imaging plane, and is not suitable for the measurement of all sizes of airways.In order to improve the geometric measurement accuracy of small airway, a parameter fitting method based on the mathematical model of CT imaging process is used in this paper.The method firstly uses Bresenham algorithm to check the gray value of the ray through the airway wall to get the real gray contour of the ray. Then the mathematical model of simulating CT fuzzy is constructed. Finally, the simulated gray contour and the real gray contour are fitted by the Levenberg-Marquardt algorithm.Thus, the model parameter estimation which is closest to the real gray contour is obtained-the inner and outer diameter estimation of the airway.In this paper, the fuzzy model introduced in CT imaging process is modeled, which is suitable for geometric measurement of different sizes of airways.In order to verify the effectiveness of the proposed method, seven 2-D ideal annular channel models with different pipe diameters are simulated by Monte Carlo projection simulation toolkit (V4r2.3.2), and then the half-height width method and the present method are used to measure the simulation figures respectively.The results show that the proposed method has high measurement accuracy and stability when the model is small and thin-walled.The two methods were used to measure the airway of 15 cases of COPD patients with RB1 inspiratory phase 3-5 stage CT images of airway chest.The results show that the difference between the two methods is mainly in the measurement of 5-stage airways, and the results obtained by this method are more stable than that of the half-high width method.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R311

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