Diaphragmatic surface smoothness calculation method based on lipschitz exponent

Abstract

The present application provides a diaphragmatic surface smoothness calculation method based on a Lipschitz exponent. The method comprises: extracting a lung contour; extracting lung feature points; extracting a diaphragmatic surface contour line; calculating Lipschitz exponents of a diaphragmatic surface; and taking the mean value of the calculated Lipschitz exponents of the feature points as the diaphragmatic surface smoothness. According to the present application, the Lipschitz exponents are used for quantitatively measuring the diaphragmatic surface smoothness, so that the deviation caused by subjective experience of a doctor is overcome; and the larger the Lipschitz exponent is, the less smooth the diaphragmatic surface is, and the smaller the Lipschitz exponent is, the smoother the diaphragmatic surface is, thereby providing an objective reference for a clinician to determine diaphragmatic surface smoothness.

Description

Calculation method of diaphragm surface smoothness based on Lipschitz index Technical Field

[0001] The present application relates to a method for calculating diaphragm surface smoothness. Background Art

[0002] The diaphragmatic surface is located beneath the lungs, above the top of the diaphragm. Due to diaphragmatic compression, it forms a semilunar depression. Diaphragmatic surface smoothness refers to the degree of its smoothness. A non-smooth surface may be associated with pleural adhesions or pleural effusion. Patients with atelectasis may also experience imaging findings such as a loss of the diaphragmatic surface. However, clinicians currently assess diaphragmatic surface smoothness through visual inspection, followed by a subjective description of either smooth or uneven surface.

[0003] Since clinicians make diagnoses through visual inspection, the accuracy of the results is often closely related to the doctors' clinical experience. The diagnostic capabilities of doctors in underdeveloped areas are also uneven, and the accuracy and stability of the results cannot be guaranteed.

[0004] Disclosure of the invention

[0005] In view of the above problems, this application aims to propose a method for calculating diaphragm surface smoothness based on the Lipschitz index.

[0006] The present application's method for calculating diaphragm surface smoothness based on the Lipschitz index includes:

[0007] Extract lung contours;

[0008] Extract lung feature points;

[0009] Extract the diaphragm contour line;

[0010] Calculate the Lipschitz index of the diaphragmatic surface;

[0011] The average value of the Lipschitz index of each feature point is calculated as the diaphragm surface smoothness.

[0012] Preferably, the SEDUCM method is used in the extraction of lung contours; in the SEDUCM method, the input DR image is decomposed by a guided filter and input into the base layer and detail layer of the SED, and then the SED model is trained to generate a boundary map for detecting lung boundaries; the thoracic cavity and spine centerlines are extracted from the boundary map and the input CXR image, and the CXR image is divided into the left thoracic cavity and the right thoracic cavity; then, the MWT algorithm and the UCM algorithm are used to generate candidate lung regions and contours, and finally the contours with the highest confidence are selected as the left and right lung contours.

[0013] Preferably, when extracting lung feature points, the highest point, lowest point, and left and right edge vertices of the left and right lungs are extracted based on the positional relationship; the lowest point is used as the costophrenic angle vertex; the coordinates of the center point of the edge line of the lung close to the spine are calculated based on the highest point and the lowest point, the one-third point between the costophrenic angle vertex and the center point is calculated, the lower edge line between the one-third point and the center point is extracted, the slope of the straight line formed by the costophrenic angle vertex and the points on the edge line is calculated, and the point with the smallest slope is taken as the cardiophrenic angle vertex.

[0014] Preferably, in extracting the diaphragm contour line, according to the coordinates of the apex of the costophrenic angle and the apex of the cardiophrenic angle, the lung edge line between the two points is extracted as the diaphragm contour line.

[0015] Preferably, in calculating the diaphragmatic surface Lipschitz index:

[0016] Choose an appropriate analytical wavelet;

[0017] For each feature point on the diaphragm contour line, find the local maximum point near the feature point whose position does not change with the measurement variable; use the exponential fitting method to find the modulus of the local maximum point whose position does not change with the measurement variable, and further obtain its Lipschitz index.

[0018] Preferably, the analytical wavelet is a Mexican hat function which is the second-order derivative of a Gaussian function.

[0019] This application uses the Lipschitz index to quantitatively measure the smoothness of the diaphragm surface, overcoming the deviation caused by the doctor's subjective experience; the larger the Lipschitz index, the less smooth the diaphragm surface, and the smaller the Lipschitz index, the smoother the diaphragm surface, providing an objective reference for clinicians to determine the smoothness of the diaphragm surface.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a flow chart of the method for calculating diaphragm surface smoothness based on the Lipschitz index of the present application;

[0022] Figure 2 is a flow chart of the SEDUCM algorithm;

[0023] FIG3 is a schematic diagram of the locations of characteristic points of the lungs;

[0024] Figure 4 is a schematic diagram of the Mexican hat wavelet;

[0025] Figure 5 is a schematic diagram of lung contour extraction.

[0026] Best Mode for Carrying Out the Invention

[0027] The method for calculating diaphragm surface smoothness based on the Lipschitz index of the present application is described in detail below with reference to the accompanying drawings.

[0028] The method of the present application includes four steps: the first step is lung contour extraction, the second step is lung feature point extraction, the third step is diaphragm surface contour line extraction, and the fourth step is diaphragm surface smoothness calculation.

[0029] Step 1: Lung contour extraction

[0030] Lung contour extraction uses the structured edge detector-ultrametric contour map (SEDUCM) method. This method decomposes the input DR image through a guided filter and inputs it into the base and detail layers of the SED. The SED model is then trained to generate a boundary map for lung boundary detection. The thoracic cavity and spine centerlines are extracted from the boundary map and the input CXR image, dividing the CXR image into left and right thoracic cavities. Subsequently, the marker-constrained watershed transform (MWT) and ultrametric contour map (UCM) algorithm (MWT-UCM) are used to generate candidate lung regions and contours. Finally, the contour with the highest confidence is selected as the left and right lung contours.

[0031] Step 2: Extract lung feature points

[0032] Based on the positional relationship, the highest and lowest points of the left and right lungs, as well as the vertices of their respective left and right edges, were extracted. The lowest point was the apex of the costophrenic angle. The coordinates of the center point of the lung edge line on the side closest to the spine were calculated based on the highest and lowest points. The third point between the costophrenic angle apex and the center point was calculated. The lower edge line between the third point and the center point was extracted. The slope of the line formed by the costophrenic angle apex and each point on the edge line was calculated. The point with the minimum slope was recorded as the apex of the costophrenic angle.

[0033] Step 3: Extract the diaphragm contour line

[0034] According to the coordinates of the apex of the costophrenic angle and the apex of the cardiophrenic angle, the lung edge line between the two points is extracted, which is the diaphragmatic surface contour line.

[0035] Step 4: Calculate the diaphragmatic Lipschitz index

[0036] (1) Select a suitable analytical wavelet. The Mexican hat function, the second-order derivative of the Gaussian function, is used as the analytical wavelet. Its function expressions are shown in Equations 1 and 2, and its graph is shown in Figure 4.

[0037] (2) Take a characteristic point x0 on the diaphragm contour line;

[0038] (3) Find the position near the feature point that does not change with the measurement variable a→0+ The local maximum point of the transformation, where a is the wavelet scaling variable;

[0039] (4) Use exponential fitting to find the modulus of the local extreme point whose position remains unchanged, according to Estimate the Lipschitz exponent α(x0), where b is the wavelet translation variable and C is a constant;

[0040] (5) Traverse all feature points on the diaphragm contour line and calculate the mean of the Lipschitz index of each feature point.

[0041] Below, this application is described with reference to FIG5 .

[0042] Step 1: Lung contour extraction

[0043] Input lung frontal chest X-ray data (DICOM format), perform mean filter preprocessing, and extract the lung contour. The contour diagram is shown in Figure 5.

[0044] Step 2: Extract lung feature points

[0045] (1) Extraction of the highest point of the lung: extract the point with the largest vertical coordinate in the contour lines of the left and right lungs;

[0046] (2) Extraction of the apex of the costophrenic angle: The costophrenic angle is located at the lowest point of the lung. The point with the smallest vertical coordinate in the contour lines of the left and right lungs is extracted as the apex of the costophrenic angle;

[0047] (3) Extraction of the cardiophrenic angle vertex: Calculate the longitudinal midpoint of the left and right lung contours respectively, calculate the one-third point between the costophrenic angle vertex and the center point, extract the lower edge line between the one-third point and the center point, and calculate the slope of the straight line formed by the costophrenic angle vertex and each point on the edge line. The points with the maximum and minimum slopes for the left and right lungs are the corresponding two points as the cardiophrenic points of the two lungs;

[0048] Step 3: Diaphragm contour extraction

[0049] Extract the lower lung contour line between the apex of the costophrenic angle and the apex of the cardiophrenic angle, which is the diaphragmatic surface contour line;

[0050] Step 4: Calculate the Lipschitz index

[0051] Traverse each point on the diaphragm contour line and calculate the Lipschitz index.

[0052] The average value is the diaphragm surface smoothness index of this instance. Industrial Applicability

[0053] This application uses the Lipschitz index to quantitatively measure the smoothness of the diaphragm surface, overcoming the deviation caused by the doctor's subjective experience; the larger the Lipschitz index, the less smooth the diaphragm surface, and the smaller the Lipschitz index, the smoother the diaphragm surface, providing an objective reference for clinicians to determine the smoothness of the diaphragm surface.

[0054] Unless otherwise defined, all technical and / or scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which the invention relates. The materials, methods, and examples mentioned in this application are illustrative only and not restrictive.

[0055] Although the present invention has been described in conjunction with specific embodiments, those skilled in the art may make appropriate substitutions, modifications and changes within the scope of the invention of this application, and such substitutions, modifications and changes shall still fall within the scope of protection of this application.

Claims

1. A method for calculating diaphragm surface smoothness based on Lipschitz index, comprising: Extract lung contours; Extract lung feature points; Extract the diaphragm contour line; Calculate the Lipschitz index of the diaphragmatic surface; The average value of the Lipschitz index of each feature point calculated was taken as the diaphragm surface smoothness.

2. The method for calculating diaphragm surface smoothness based on Lipschitz index according to claim 1, characterized in that: The SEDUCM method is used to extract lung contours. In the SEDUCM method, the input DR image is decomposed by a guided filter and input into the base layer and detail layer of SED. Then the SED model is trained to generate a boundary map for detecting lung boundaries. The thoracic cavity and spine centerlines are extracted from the boundary map and the input CXR image, and the CXR image is divided into the left thoracic cavity and the right thoracic cavity. Subsequently, the MWT algorithm and the UCM algorithm are used to generate candidate lung regions and contours, and finally the contours with the highest confidence are selected as the left and right lung contours.

3. The method for calculating diaphragm surface smoothness based on Lipschitz index according to claim 2, characterized in that: In extracting lung feature points, the highest point, lowest point, and left and right edge vertices of the left and right lungs are extracted according to the positional relationship; the lowest point is used as the costophrenic angle vertex; the coordinates of the center point of the edge line of the lung close to the spine are calculated based on the highest point and the lowest point, the one-third point between the costophrenic angle vertex and the center point is calculated, the lower edge line between the one-third point and the center point is extracted, the slope of the straight line formed by the costophrenic angle vertex and the points on the edge line is calculated, and the point with the smallest slope is taken as the costophrenic angle vertex.

4. The method for calculating diaphragm surface smoothness based on Lipschitz index according to claim 3, characterized in that: In extracting the diaphragm contour, according to the coordinates of the apex of the costophrenic angle and the apex of the cardiophrenic angle, the lung edge line between the two points is extracted as the diaphragm contour.

5. The method for calculating diaphragm surface smoothness based on Lipschitz index according to claim 4, characterized in that: In calculating the diaphragmatic Lipschitz index: Choose an appropriate analytical wavelet; For each feature point on the diaphragm contour line, find the local maximum point near the feature point whose position does not change with the measurement variable; use exponential fitting to find the local maximum point whose position does not change with the measurement variable. The modulus of the local maximum point is obtained, and its Lipschitz index is further obtained.

6. The method for calculating diaphragm surface smoothness based on Lipschitz index according to claim 5, characterized in that: The analytical wavelet is the Mexican hat function of the second-order derivative of the Gaussian function.

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