發(fā)布時間：2018-04-17 02:21

  本文選題：癌癥骨轉(zhuǎn)移 + CT斷層圖像�。� 參考：《揚州大學》2017年碩士論文

【摘要】：癌癥腫瘤在中晚期常常伴隨著骨骼尤其是脊椎骨區(qū)域的轉(zhuǎn)移。計算機輔助診斷系統(tǒng)能夠依據(jù)CT斷層圖像提供的像素信息協(xié)助影像科醫(yī)師及早發(fā)現(xiàn)脊椎骨轉(zhuǎn)移的病灶。脊椎骨區(qū)域的分割作為CT斷層圖像處理中的重要步驟之一,一方面能夠極大地減少脊椎骨區(qū)域配準以及骨轉(zhuǎn)移識別的時間;另一方面其分割精度也直接影響著計算機輔助診斷系統(tǒng)的確診率。論文針對多名骨轉(zhuǎn)移患者CT斷層圖像,在研究數(shù)學形態(tài)學運算、連通區(qū)域標記算法以及圖割算法理論的基礎上,實現(xiàn)了脊椎骨區(qū)域的自動式、交互式以及兩者相結合的分割,論文主要工作如下:(1)采用數(shù)學形態(tài)學運算對脊椎骨區(qū)域進行預處理,在保證骨轉(zhuǎn)移患者的CT斷層圖像中各個器官、組織擁有明顯灰度級差別的前提下,通過減弱圖像二值化結果中的椒鹽噪聲,有效地避免了其它器官、組織的誤分割,極大地提高了基于標記算法的脊椎骨區(qū)域分割的準確率。(2)提出一種基于標記算法的脊椎骨區(qū)域自動式分割方法,先后采用基于連通區(qū)域標記算法的二值化脊柱區(qū)域快速填補和基于行程標記算法的脊椎骨區(qū)域分割兩個主要步驟,解決了由于癌癥骨轉(zhuǎn)移病灶的侵蝕致使患者CT斷層圖像中的脊椎體邊緣模糊,無法保證高質(zhì)量邊緣信息提取的問題,使得計算機輔助診斷早期骨轉(zhuǎn)移病灶成為可能。(3)基于經(jīng)典Graph Cuts算法,提出了針對CT斷層圖像中脊椎骨區(qū)域分割的前景(目標)和背景區(qū)域初始種子點的選取方法。該方法在保證脊椎骨區(qū)域有效分割的條件下,選取矩形像素區(qū)域作為約束條件,避免了大范圍的迭代運算,從而較大程度地降低了 Graph Cuts算法的處理時間,提高了分割的效率。(4)提出了一種改進Graph Cuts方法。該方法首先運用基于連通區(qū)域標記算法與數(shù)學形態(tài)學運算實現(xiàn)了脊柱區(qū)域分割,再利用Graph Cuts算法實現(xiàn)了脊椎骨區(qū)域的最終分割,解決了由于脊柱CT斷層圖像灰度級梯度幅值小導致經(jīng)典Graph Cuts算法對脊椎體邊緣分割不敏感的問題。(5)提出了一種基于區(qū)域像素點的真陽性率(TPR)和假陽性率(FPR)的分割結果評價方法。該評價法以日本產(chǎn)業(yè)醫(yī)科大學多名資深影像科醫(yī)師的人工分割作為參照標準,對基于經(jīng)典Graph Cuts算法以及本文改進Graph Cuts方法的脊椎骨區(qū)域分割結果分別進行量化分析。分析結果表明:改進的Graph Cuts算法能夠更好地分割脊椎骨的區(qū)域與邊緣,為進一步的圖像處理以及骨轉(zhuǎn)移病灶的診斷提供了準確的病變組織信息。
[Abstract]:Cancer tumors are often associated with bone metastasis, especially in the vertebral region, in the middle and late stages.The computer aided diagnosis system can help the radiologist to detect the metastatic lesions of vertebral vertebrae early according to the pixel information provided by CT tomographic images.As one of the important steps in CT image processing, the segmentation of vertebral region can greatly reduce the time of registration and recognition of bone metastasis.On the other hand, its segmentation accuracy also directly affects the diagnosis rate of computer aided diagnosis system.In this paper, based on the research of mathematical morphology, connected area marking algorithm and image cutting algorithm, the automatic, interactive and combined segmentation of vertebral region is realized.The main work of this paper is as follows: (1) preprocessing the vertebral region by mathematical morphological operation to ensure that there are obvious grayscale differences in the organs and tissues of CT images of patients with bone metastasis.By reducing the salt and pepper noise in the binary image, the missegmentation of other organs and tissues is effectively avoided.It greatly improves the accuracy of vertebrae region segmentation based on marking algorithm. (2) an automatic segmentation method based on marking algorithm is proposed.There are two main steps: fast filling of spinal region based on connected region marking algorithm and segmenting of vertebrae region based on itinerary marker algorithm.It solves the problem that the edge of vertebral body in CT tomography image is blurred due to the erosion of cancer bone metastases, which can not guarantee the high quality edge information extraction.Based on the classical Graph Cuts algorithm, this paper proposes a method to select the foreground (target) and initial seed points of the background region in CT tomography.Under the condition that the vertebral region can be effectively segmented, the rectangular pixel region is chosen as the constraint condition, which avoids the iterative operation in a wide range, thus greatly reducing the processing time of the Graph Cuts algorithm.An improved Graph Cuts method is proposed.In this method, the spinal region is segmented based on the connected region marking algorithm and the mathematical morphology operation, and the final segmentation of the vertebra region is realized by using the Graph Cuts algorithm.This paper solves the problem that the classical Graph Cuts algorithm is insensitive to spinal body edge segmentation due to the small grayscale gradient amplitude of spine CT image. A method for evaluating the segmentation results of true positive rate and false positive rate based on regional pixels is proposed.The evaluation method is based on the artificial segmentation of many senior imaging physicians in Japan University of Technology and Medical Sciences as a reference standard. The results of the segmenting of the vertebrae region based on the classical Graph Cuts algorithm and the improved Graph Cuts method in this paper are quantitatively analyzed respectively.The results show that the improved Graph Cuts algorithm can better segment the region and edge of vertebrae and provide accurate tissue information for further image processing and diagnosis of bone metastases.
【學位授予單位】：揚州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：R816.8;TP391.41

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本文編號：1761643