A method for extracting spine point cloud based on 3D CT

Abstract

The present invention discloses a method for extracting spine point cloud based on three-dimensional CT, comprising the following steps: S1, removing the scanning bed; S2, positioning the patient's mid-sagittal plane MSP so that it is parallel to the anterior-posterior axis of the image; S3, positioning the left and right PSIS coordinates and assuming that the left and right PSIS coordinates are located on the same axial slice; S4, displaying the skin on the CT in a window; S5, extracting the point cloud connected to the PSIS coordinates; S51, starting from the column corresponding to the left PSIS coordinate in the axial slice k containing the PSIS coordinates, and ending at the column corresponding to the right PSIS coordinate j; S52, finding the last pixel of the column in the slice, and saving their 3D coordinates; S6, extracting the point cloud of the spine line; S61, searching in each frame of the axial slice k; S62, finding the last pixel on the column according to the MSP, and saving their 3D coordinates. The present invention provides a basis for the subsequent calibration of the electromagnetic coordinate system and the CT coordinate system.

Description

Technical Field

[0001] The invention belongs to the technical field of image processing, and in particular relates to a spine point cloud extraction method based on three-dimensional CT. Background Art

[0002] In recent years, medical imaging technology has developed rapidly, and computed tomography (CT) and magnetic resonance imaging (MR) are widely used in clinical diagnosis. CT is widely used because of its fast scanning speed and reasonable price, and it also plays a very important role in the diagnosis and treatment of spine.

[0003] The CT system uses precisely collimated X-rays and highly sensitive detectors to receive signals that pass through the human body. The scanned data is then reconstructed using an image reconstruction algorithm to form a tomographic image. In recent years, with the development of multi-slice spiral CT technology, the number of rows of detectors has increased from 4 rows to 64 rows to the current 256-row CT. This has brought with it a huge amount of data that needs to be interpreted by doctors, so computer-assisted analysis has become very important. For example, in a CT scan of the spine, a positioning image of the spine is usually scanned, and then doctors generally manually select the position and direction of each spine so that the CT system can scan each spine along the direction of the spine. For another example, in spinal orthopedic surgery, doctors are usually required to identify the position of each spine and regenerate tomographic images according to the spatial direction of each spine, and then diagnose the health of the patient's spine. In this process, manual interpretation of information such as the degree of curvature and the direction of curvature is usually required. When performing the above computer-assisted analysis, it is necessary to establish an accurate electromagnetic coordinate system and a CT coordinate system to facilitate the auxiliary analysis. Summary of the invention

[0004] The purpose of the present invention is to provide a method for extracting spine point clouds based on three-dimensional CT to solve the above problems. The point cloud is extracted and registered using CT bone information, and the point cloud can match the sagittal line and transverse line of the patient's spine, which connect the left and right PSIS points, thereby providing a basis for the subsequent calibration of the electromagnetic coordinate system and the CT coordinate system.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] A spine point cloud extraction method based on three-dimensional CT includes the following steps:

[0007] S1, remove the scanning bed;

[0008] S2. Position the patient's mid sagittal plane (MSP) so that it is parallel to the anterior-posterior axis of the image.

[0009] S3, locate the left and right PSIS coordinates and assume that the left and right PSIS coordinates are located on the same axial slice;

[0010] S4, window displays the skin on CT;

[0011] S5, point cloud extraction connected to PSIS coordinates;

[0012] S51, in the axial slice k containing the PSIS coordinates, starting from the column corresponding to the left PSIS coordinates and ending at the column corresponding to the right PSIS coordinates j;

[0013] S52, find the last pixel of the column in the slice, and save their 3D coordinates;

[0014] S6, point cloud extraction of spine line;

[0015] S61, searching in each axial slice k;

[0016] S62. Find the last pixels on the column according to MSP and save their 3D coordinates.

[0017] As an improvement to the above technical solution, in step S2, if the MSP cannot be parallel to the anterior-posterior axis of the image, it is rotated and aligned.

[0018] As an improvement to the above technical solution, the rotational alignment refers to reverse rotational alignment.

[0019] As an improvement to the above technical solution, in step S52 and step S62, the coordinate values ​​of the 3D coordinates are represented by x, y, and z.

[0020] Compared with the prior art, the present invention has the following advantages and positive effects:

[0021] The spine point cloud extraction method based on three-dimensional CT of the present invention utilizes CT bone information to extract and register point clouds, which can match the sagittal line and transverse line of the patient's spine. These two lines connect the left and right PSIS points, thereby providing a basis for the subsequent calibration of the electromagnetic coordinate system and the CT coordinate system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1This is a schematic diagram of the original CT slice, when the bed is under the patient's body;

[0024] Figure 2 It is a schematic diagram of a slice containing the left and right PSIS. In the figure, the cross on the left represents the left PSIS coordinate, the cross on the right represents the right PSIS coordinate, the vertical line represents the MSP surface, and the horizontal line represents the top of the bed;

[0025] Figure 3 This is a schematic diagram of the result of extracting the spine point cloud according to the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work, any modifications, equivalent substitutions, improvements, etc., should be included in the protection scope of the present invention.

[0027] like Figures 1 to 3 As shown, this embodiment discloses a spine point cloud extraction method based on three-dimensional CT, comprising the following steps:

[0028] S1. Remove the scanning bed.

[0029] S2. Position the patient's mid sagittal plane (MSP). If the MSP cannot be aligned parallel to the anterior-posterior axis of the image, rotate it to align.

[0030] S3. Locate the left and right PSIS coordinates (assuming they are on the same axial slice).

[0031] S4. In custom, the window displays the skin on CT.

[0032] S5. Point cloud extraction connected to PSIS:

[0033] In the axial slice k containing the PSIS, start from the column corresponding to the left PSIS and end at the column j corresponding to the right PSIS.

[0034] Find the last pixel in the column of the slice and save its 3D coordinates (x,y,z).

[0035] S6. Point cloud extraction of spine line:

[0036] Search in each axial slice k.

[0037] Find the last pixel in the column according to MSP(j) and save their 3D coordinates (x, y, z);

[0038] S7. If necessary, perform inverse rotation (from step 2a to two point clouds).

Claims

1. A spine point cloud extraction method based on three-dimensional CT, characterized in that: The steps include: S1, remove the scanning bed; S2, position the patient's midsagittal plane MSP so that it is parallel to the anterior-posterior axis of the image; S3, locate the left and right PSIS coordinates and assume that the left and right PSIS coordinates are located on the same axial slice; S4, window displays the skin on CT; S5, point cloud extraction connected to PSIS coordinates; S51, in the axial slice k containing the PSIS coordinates, starting from the column corresponding to the left PSIS coordinates and ending at the column corresponding to the right PSIS coordinates j; S52, find the last pixel of the column in the slice, and save their 3D coordinates; S6, point cloud extraction of spine line; S61, searching in each axial slice k; S62. Find the last pixels on the column according to MSP and save their 3D coordinates.

2. The spine point cloud extraction method based on three-dimensional CT according to claim 1, characterized in that: In step S2, if the MSP cannot be parallel to the anterior-posterior axis of the image, it is rotationally aligned.

3. The spine point cloud extraction method based on three-dimensional CT as claimed in claim 2, characterized in that: The rotational alignment is a counter-rotational alignment.

4. The spine point cloud extraction method based on three-dimensional CT according to claim 1, characterized in that: In step S52 and step S62, the coordinate values ​​of the 3D coordinates are expressed by x, y, and z.

Images