【摘要】：現(xiàn)今,醫(yī)用內(nèi)窺鏡已經(jīng)作為一種直觀的醫(yī)療設(shè)備,被廣泛應(yīng)用于病情診斷和手術(shù)治療過程。然而,對于傳統(tǒng)的使用單相機(jī)的內(nèi)窺鏡系統(tǒng),醫(yī)生通過顯示器只能觀察到二維圖像,依靠經(jīng)驗(yàn)判斷病灶的尺寸,選擇手術(shù)器械,很容易因?yàn)榕袛嗍д`導(dǎo)致手術(shù)時(shí)間過長甚至醫(yī)療事故。針對以上問題,本文提出并實(shí)現(xiàn)了基于棱鏡的立體內(nèi)窺鏡系統(tǒng)。該系統(tǒng)利用棱鏡折射的分光作用,在不增加內(nèi)窺鏡直徑的前提下,通過立體視覺的整套算法流程,可以精確地測量出人體內(nèi)部組織器官和病灶的大小,以輔助診斷的方式指導(dǎo)醫(yī)生進(jìn)行高效精確的手術(shù)。本文完成的主要工作有： 第一,針對基于棱鏡的立體視覺系統(tǒng),定義“有效區(qū)間”和“最優(yōu)距離”的概念。通過分析相機(jī)參數(shù)和棱鏡參數(shù)對系統(tǒng)捕獲圖像質(zhì)量的影響,給出了選擇相機(jī)和棱鏡的方法和標(biāo)準(zhǔn)。 第二,提出一種可以表示棱鏡折射過程的幾何光學(xué)模型。將棱鏡看成一個(gè)由許多平面組成的光學(xué)系統(tǒng),根據(jù)幾何光學(xué)的基本原理,通過分析推導(dǎo)出可以表示棱鏡折射過程的數(shù)學(xué)模型,該模型以矩陣的形式表示出棱鏡折射前后物點(diǎn)和像點(diǎn)的關(guān)系,可以用于任意位置、任意視角棱鏡成像的計(jì)算。 第三,提出棱鏡位置計(jì)算方法。根據(jù)第二部分的理論,針對現(xiàn)有的棱鏡單目立體視覺算法中理論體系不夠完善,誤差較大的缺點(diǎn),提出了一種棱鏡位置的計(jì)算方法。該方法將表示棱鏡位置的參數(shù)簡化為7個(gè),通過推導(dǎo)出棱鏡立體視覺系統(tǒng)的透視投影變換模型,利用差分進(jìn)化算法解出這7個(gè)參數(shù),從而得到精確的棱鏡位置。 第四,提出基于棱鏡立體視覺系統(tǒng)的極線幾何關(guān)系和三維重建方法。利用光線追跡結(jié)合棱鏡成像,給出了棱鏡立體視覺系統(tǒng)的極線幾何關(guān)系。根據(jù)局部匹配算法找到對應(yīng)點(diǎn),通過求解兩直線公垂線交點(diǎn)的方法進(jìn)行空間點(diǎn)的三維重建。整套算法流程建立在精確的數(shù)學(xué)模型基礎(chǔ)之上,可以應(yīng)用于任何棱鏡立體視覺系統(tǒng)。 第五,根據(jù)以上的理論基礎(chǔ),設(shè)計(jì)并實(shí)現(xiàn)了醫(yī)用內(nèi)窺鏡輔助診斷系統(tǒng)。整個(gè)系統(tǒng)由硬件部分和軟件部分組成,分別完成圖像獲取和圖像處理的任務(wù)。與現(xiàn)有的醫(yī)用內(nèi)窺鏡系統(tǒng)相比,本文設(shè)計(jì)的系統(tǒng),通過人機(jī)交互的方式,在顯示圖像的同時(shí),可以計(jì)算出用戶感興趣的物體長度,為醫(yī)生提供更加豐富的信息,起到輔助診斷和治療的作用。 實(shí)驗(yàn)結(jié)果表明,本文提出的整套棱鏡立體視覺算法流程可以得到物體在三維空間中的精確坐標(biāo)。與現(xiàn)有方法相比,可以將三維重建的精度提高2至6倍。可以擴(kuò)大棱鏡立體視覺系統(tǒng)的應(yīng)用范圍,并且很好地應(yīng)用于棱鏡立體內(nèi)窺鏡系統(tǒng)。
[Abstract]:Nowadays, medical endoscopy has been widely used in diagnosis and surgical treatment as an intuitionistic medical device. However, for traditional endoscopy systems using a single camera, doctors can only observe two-dimensional images through monitors, judge the size of lesions by experience, and select surgical instruments. It is easy to cause too long operation time or even medical malpractice because of wrong judgment. In order to solve the above problems, a prism-based stereoscopic endoscope system is proposed and implemented in this paper. The system can accurately measure the size of organs and lesions of human body through the whole algorithm flow of stereoscopic vision without increasing the diameter of endoscope. To guide doctors to perform efficient and accurate operations in the form of auxiliary diagnosis. The main works of this paper are as follows: first, the concepts of "effective interval" and "optimal distance" are defined for the prism based stereo vision system. By analyzing the influence of camera parameters and prism parameters on the image quality of the system, the method and standard of selecting camera and prism are presented. Secondly, a geometric optical model which can represent the refractive process of prism is proposed. The prism is regarded as an optical system composed of many planes. According to the basic principle of geometric optics, the mathematical model which can represent the refraction process of the prism is derived through analysis. The model can be used to calculate the imaging of prism at any position and angle of view because it represents the relation between the point of object and the point of view before and after refraction of the prism in the form of matrix. Thirdly, a prism position calculation method is proposed. According to the theory of the second part, a method for calculating the position of prism is proposed to solve the problem that the theoretical system is not perfect and the error is large in the existing algorithm of prism monocular stereo vision. By deducing the perspective projection transformation model of the prism stereo vision system and using the differential evolution algorithm to solve the seven parameters, the accurate prism position can be obtained. Fourthly, a method of polar geometric relation and 3D reconstruction based on prism stereo vision system is proposed. Using ray tracing combined with prism imaging, the polar geometric relationship of prism stereo vision system is given. According to the local matching algorithm, the corresponding points are found, and the 3D reconstruction of spatial points is carried out by solving the intersection points of two linear common perpendicular lines. The whole algorithm is based on accurate mathematical model and can be applied to any prism stereo vision system. Fifthly, according to the above theoretical basis, a medical endoscope aided diagnosis system is designed and implemented. The whole system is composed of hardware part and software part, and accomplishes the task of image acquisition and image processing respectively. Compared with the existing medical endoscope system, the system designed in this paper, by means of human-computer interaction, can calculate the length of objects of interest to the user while displaying images, and provide more abundant information for doctors. Play an auxiliary role in diagnosis and treatment. The experimental results show that the complete prism stereo vision algorithm can get the exact coordinates of objects in three dimensional space. Compared with the existing methods, the accuracy of 3D reconstruction can be improved by 2 to 6 times. It can expand the application of prism stereoscopic vision system, and it can be applied to prism stereoscopic vision system.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2012
【分類號】：R443.8

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本文編號：2418319