Computer-aided automatic skin removal method in cone-beam breast CT images

Abstract

The application provides a computer-aided automatic skin removing method in a cone-beam breast CT image, comprising the following steps: S1, obtaining a projection image through CBBCT; S2, image preprocessing; S3, separating the whole breast from air in the image; S4, searching for CBBCT pixels belonging to skin from the skin edge position of the breast inward; S5, marking the pixels belonging to skin; S6, skin thickness estimation; S7, controlling the display effect of skin; in S4, each projection image is marked with a color area, and the skin contour is searched in the color area. The application can display the breast gland inside the breast, and can see through the breast surface layer in the three-dimensional image to interpret the condition of the breast inside.

Description

Technical Field

[0001] This invention belongs to the field of graphics algorithms, and in particular relates to a computer-aided automatic skin removal method in cone-beam mammography. Background Technology

[0002] According to the latest data from the World Health Organization, breast cancer has surpassed lung cancer to become the most common cancer and the leading cause of cancer death among women. Currently, there are no effective methods to prevent or control breast cancer. If breast cancer is diagnosed and treated early, the 5-year survival rate can be as high as 99%. The lower survival rate of breast cancer in underdeveloped areas is generally attributed to the lack of effective early detection methods and screening systems, leading to many women being diagnosed at a relatively late stage, missing the optimal treatment window. Early screening and early diagnosis remain the most important methods for improving breast cancer survival rates and extending survival time; breast imaging methods are the primary means of early breast cancer detection. The commonly used mammography method utilizes X-rays. Mammography, with its advantages of good imaging quality and low cost, has been proven effective in reducing breast cancer mortality over long-term use. Therefore, mammography is recommended as the primary breast cancer screening method for women of general risk. However, as a two-dimensional imaging method, mammography involves compressing the breast to capture projected images, resulting in overlapping breast tissue. This not only leads to a poor patient experience but also significantly reduces the imaging quality for women of East Asian descent, who often have denser, smaller breasts. Studies show that for dense breasts, the sensitivity of mammography is less than 40%.

[0003] The Cone Beam Breast CT (CBBCT) system is a three-dimensional breast imaging technology based on cone-beam X-rays and a high-speed flat panel detector. It is currently the world's only commercially available breast CT system. With its advantages of no compression, low dose, true three-dimensionality, high resolution, and no tissue overlap, this system has been applied in the field of breast imaging, demonstrating its superiority over existing mammography in various aspects. Currently, CBBCT has accumulated considerable experience and data in the diagnosis of breast cancer.

[0004] In existing CBBCT images, the visualization of breast skin uses the same method as the visualization of the entire breast. The biological characteristics of breast skin result in its CT value being generally higher than that of the fibrous and fatty glands within the breast. Therefore, in CBBCT 3D imaging, the visualization of breast skin overshadows the visualization of the internal breast tissue, making it impossible to see through the surface of the breast and interpret the internal condition. Summary of the Invention

[0005] In view of this, the present invention aims to propose a computer-aided automatic skin removal method in cone-beam mammography to display the internal glandular tissue of the breast and to interpret the internal condition of the breast by seeing through the surface of the breast in three-dimensional images.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A computer-aided automatic skin removal method for cone-beam mammography images includes the following steps:

[0008] S1. Obtain the projected image through CBBCT;

[0009] S2, Image preprocessing;

[0010] S3. The image separates the entire breast from the air;

[0011] S4. Locate the CBBCT pixels belonging to the skin from the edge of the breast skin inwards;

[0012] S5. Label the CBBCT pixels belonging to the skin;

[0013] S6. Skin thickness estimation;

[0014] S7. Controls the skin display effect, which includes turning skin display on and off; turning skin display on displays the unadjusted skin pixels; turning skin display off reduces the CT value of the skin pixels, thereby revealing the internal tissues covered by the skin.

[0015] The formula for updating skin pixel CT values ​​is:

[0016] μ′=μ-μ·f dist ;

[0017] Where μ is the original CT value of the target pixel, and μ' is the updated CT value; the distance coefficient f dist The estimation formula is influenced by the normalized distance d between the target pixel and the skin edge:

[0018] f dist =0.82·d 3 -1.23·d 2 +0 .11·d+0 .3.

[0019] Furthermore, in S4, each projected image is marked with a different colored region, and the skin contour is retrieved within the different colored region.

[0020] Furthermore, the starting point of the local skin contour is located at the edge of the appearance. The normal direction of the skin surface is calculated, and the contour is retrieved along this normal direction. Then, the local contours starting from all starting points in all projected images are averaged and fitted to obtain the average skin contour.

[0021] Compared with existing technologies, the computer-aided automatic skin removal method for cone-beam mammography images described in this invention has the following advantages:

[0022] (1) The computer-aided automatic skin removal method in cone beam breast CT images described in this invention, when the skin display is turned on, the unadjusted skin pixels appear normally in the image, and when the skin display is turned off, the CT value of the skin pixels in the image is reduced, thereby allowing the internal tissues covered by the skin to be displayed. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 This is a schematic diagram of the projection image obtained by CBBCT as described in an embodiment of the present invention;

[0025] Figure 2 This is the average skin contour curve diagram described in the embodiments of the present invention;

[0026] Figure 3 This is a skin pixel CT value update curve as described in an embodiment of the present invention;

[0027] Figure 4 This is a partial block diagram illustrating the principle of a computer-aided automatic skin removal method in cone-beam mammography as described in an embodiment of the present invention.

[0028] Figure 5 This is a block diagram illustrating the principle of image changes generated by the computer-aided automatic skin removal method in cone-beam mammography as described in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Starting point; 2. Normal line. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] A computer-aided automatic skin removal method for cone-beam mammography images includes the following steps:

[0036] S1. Obtain the projected image through CBBCT;

[0037] S2, Image preprocessing;

[0038] S3. The image separates the entire breast from the air;

[0039] S4. Locate the CBBCT pixels belonging to the skin from the edge of the breast skin inwards;

[0040] S5. Label the pixels belonging to the skin;

[0041] S6. Skin thickness estimation;

[0042] S7. Controls the display effect of the skin.

[0043] Furthermore, in S4, each projected image is marked with a different colored region, and the skin contour is retrieved within the different colored region.

[0044] Furthermore, the starting point of the local skin contour is located at the edge of the appearance. The normal direction of the skin surface is calculated, and the contour is retrieved along this normal direction. Then, the local contours starting from all starting points in all projected images are averaged and fitted to obtain the average skin contour.

[0045] Furthermore, in S7, the skin display effect includes turning the skin display on and off; when the skin display is on, it is displayed as unadjusted skin pixels; when the skin is off, the CT value of the skin pixels is reduced, thereby allowing the internal tissues covered by the skin to be displayed.

[0046] Furthermore, the formula for updating skin pixel CT values ​​is as follows:

[0047] μ′=μ-μ·f dist ;

[0048] Where μ is the original CT value of the target pixel, and μ' is the updated CT value. Distance coefficient f dist The estimation formula is influenced by the normalized distance d between the target pixel and the skin edge:

[0049] f dist =0.82·d 3 -1.23·d 2 +0 .11·d+0 .3.

[0050] Compared to existing technologies, the present invention provides a computer-aided automatic skin removal method for cone-beam mammography images. When skin display is enabled, unadjusted skin pixels appear normally in the image. When skin display is disabled, the CT value of skin pixels in the image is reduced, thereby allowing internal tissues covered by skin to be displayed.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A computer-aided automatic skin removal method for cone-beam mammography images, comprising the following steps: S1. Obtain the projected image through CBBCT; S2, Image preprocessing; S3. The image separates the entire breast from the air; S4. Locate the CBBCT pixels belonging to the skin from the edge of the breast skin inwards; S5. Label the CBBCT pixels belonging to the skin; S6. Skin thickness estimation; S7. Controls the skin display effect, which includes turning skin display on and off; turning skin display on displays the unadjusted skin pixels; turning skin display off reduces the CT value of the skin pixels, thereby revealing the internal tissues covered by the skin. The formula for updating skin pixel CT values ​​is: μ′=μ-μ·f dist ; Where μ is the original CT value of the target pixel, and μ' is the updated CT value; the distance coefficient f dist The estimation formula is influenced by the normalized distance d between the target pixel and the skin edge: f dist =0 .82·d 3 -1 .23·d 2 +0 .11·d+0 .3。 2. The computer-aided automatic skin removal method for cone-beam mammography images according to claim 1, characterized in that: In S4, each projected image is marked with a different colored region, and the skin contour is retrieved within the different colored region.

3. The computer-aided automatic skin removal method for cone-beam mammography images according to claim 2, characterized in that: The starting point of the local skin contour is located at the edge of the appearance. The normal direction of the skin surface is calculated, and the contour is retrieved along this normal direction. Then, the local contours starting from all starting points in all projected images are averaged to obtain the average skin contour.

Images