| When radiologists diagnose pulmonary diseases such as chronic obstructive pulmonary disease and lung cancer in lung CT images,it is necessary to analyze and measure the associated quantification indicators of pulmonary function by means of computer software techniques,which aid in assessment of the patient’s pulmonary function.The quantitative analysis of pulmonary function based on CT images has more advantages than conventional pulmonary function tests(PFT).It is not only simply manipulated and has the high reproducibility,but also reflects the local pulmonary function.In addition,it significantly improves the competency to exhibit the subtle lung structures,which is very helpful for the early detection of lung disease,the assessment of the disease progression and the monitoring of postoperative prediction.At present,the quantitative analysis of pulmonary function has become a research focus.To this end,we independently develop a computer-assisted system of the quantitative analysis of pulmonary function based on volume visualization in this paper,which is applied to aid the doctor to assess the patient’s pulmonary function.The main contents of this paper are summarized as follows:1)To obtain the object for quantitative analysis of pulmonary function,the relative study of lung tracheal tree,lung parenchyma and pulmonary vascular segmentation was made.First,the rough segmentation results of lung tissues are obtained by the global thresholding method.Then,the pulmonary tracheal tree is extracted from the rough segmentation results by the optimal threshold growth method and the leakage detection mechanism is introduced.Next,combined with morphological processing,interactive segmentation repair and so on,the results of lung parenchyma segmentation are obtained.Finally,the eigenvalues of the three-dimensional Hessian matrix and shape index are incorporated to construct the measurement function of vessels.Thus,the pulmonary vessels is extracted from the pulmonary parenchyma.2)To clearly display the relative position information of various lung tissues in three-dimensional space and avoid the mutual occlusion of the volume of different tissues in the volume rendering process,we designed a transfer function based on the classification for volume rendering.It provides a convenient interactive transfer function tool and can render the high quality lung tissues at the same time.3)To quantitatively analyze the lung function regarding local lung tissues,we achieve the interactive two-dimensional ROI(region of interest)segmentation and three-dimensional VOI(volume of interest)segmentation.In order to observe the distribution information of the pixel sets in the lungs of different CT values in the data field,the pseudo-color technique is used to distinguish different CT-valued pixels from different colors,which can intuitively show the extent of the lesion and its severity.4)Benefiting from the abovementioned technical results,we design and develop a computer-assisted system of the quantitative analysis of lung function based on volume visualization in this paper.This system realizes the quantitative analysis of pulmonary function on two-dimensional CT images and three-dimensional CT image sequences.It can calculate the quantification indicators of lung function,such as the total lung volume of the whole lung,left lung and right lung,the functional lung volume,non-functional lung volume,pixel index,mean lung density and standard deviation.In addition,the system is provided to realize a quantitative analysis of lung function of local lung tissues in two-dimensional lung ROI and three-dimensional lung VOI.It provides an interactive parameter setting to calculate the quantitative indicators of lung function in the specified CT value interval of the volume data filed.This system can be applied to the diagnosis of lung disease,such as chronic obstructive lung disease and lung cancer.It also can aid in assessment of patient’s pulmonary function. |
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