KR101211143B1 - Physical phantom for detection of central axis shift and tilting in cone-beam x-ray computed tomography - Google Patents

Abstract

PURPOSE: A physical phantom for detecting central axis shift and tilting of an X-ray CT photographing device is provided to easily detect the tilting of the X-ray CT photographing device by proving a clear contour line in a scanned 2D projection image. CONSTITUTION: A physical phantom includes an outer pillar(110), a first inner pillar(120), and a second inner pillar(130). The first inner pillar is located in the inside of the outer pillar. The second inner pillar is located on the lower part of the first inner pillar. The central axes of the first inner pillar and second inner pillar are same as the central axis of the outer pillar. The first inner pillar is scanned into a vertical axis corresponding to a standard for measuring a central axis in a 2D projection image. The second inner pillar is scanned into a vertical axis corresponding to a standard for measuring tilting in the 2D projection image.

Description

Physical phantom for detection of central axis shift and tilting in cone-beam x-ray computed tomography

The present invention relates to a physical phantom for moving the center of rotation and tilt detection of the X-ray Citigraphy apparatus, and more specifically, to the vertical axis and tilt as a reference for measuring the center of rotation in the two-dimensional projection image scanned by the X-ray Citi apparatus Scanned on the vertical axis, which is a reference for measuring the load, to detect the rotational center and tilt of the X-ray Citigraphic apparatus, which makes it easy to detect the tilt and rotational center of the two-dimensional projection data input from the X-ray Citigraphic apparatus. To physical phantoms.

In general, a three-dimensional tomographic system, such as X-ray computed tomography, is the most widely used equipment for acquiring medical images. Enables to acquire an image as a 3D image.

In addition, the X-ray CIT apparatus obtains a plurality of two-dimensional images first to obtain the three-dimensional image, and then reconstructs the two-dimensional images through mathematical calculation to obtain the three-dimensional image.

In addition, a technique for reconstructing the 2D images into a 3D image has been technically developed from a 2D image reconstruction technique, and representative 2D image reconstruction techniques include parallel-beam reconstruction technique and ecuangular fan beam reconstruction. fan-beam reconstruction and equal-spaced fan-beam reconstruction.

In addition, a typical three-dimensional image reconstruction technique is a cone-beam reconstruction technique, also called a FDK (Feldkamp) technique, and is based on the two-dimensional equal space fan beam reconstruction technique to enable three-dimensional processing. Three-dimensional reconstruction technique with an extended axis.

Meanwhile, the 3D projection reconstruction technique receives 2D projection data obtained by rotating an X-ray source and a detector of the X-ray Citi apparatus and reconstructs it into a 3D image through mathematical calculation. The 3D image is reconstructed without considering the movement or tilt of the center of rotation of the 2D projection data.

Therefore, when the center point of the X-ray source of the X-ray device and the central axis of the detector are not located at the correct position and the rotation center is moved, blurring phenomenon in a 3D image may be caused. A problem arises.

In addition, when the 2D projection data is acquired in an inclined state due to factors such as an error occurring in the X-ray Citigraphic apparatus itself, a mechanical defect, or vibration during driving, the inclination value of all the 2D projection data is as much as the inclination value. There is a problem that an error occurs, and a problem that cannot be reconstructed into an accurate three-dimensional image occurs.

When the inventors reconstruct the two-dimensional projection data input from the X-ray Citigraphic apparatus into a three-dimensional image, the present inventors have tried to make it possible to quickly and accurately detect the movement and inclination of the rotation center generated from the two-dimensional projection data. The present invention has been completed by developing a technical configuration of a physical phantom for the rotational center movement and tilt detection of an X-ray Citigraphic apparatus.

Accordingly, an object of the present invention is to provide a physical phantom for the rotational center movement and the tilt detection of the X-ray Citigraphic apparatus that can accurately detect the center of rotation and tilt of the two-dimensional projection data input from the X-ray Citigraphic apparatus .

In addition, another object of the present invention is to rotate the X-ray Citigraphic apparatus providing a vertical axis as a reference for measuring the state of the rotation center of the X-ray Citigraphy apparatus and a horizontal axis as a reference for measuring the inclination of the X-ray Citi apparatus It is to provide a physical phantom for center movement and tilt detection.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention provides a vertical axis as a reference within the two-dimensional projection image scanned by the X-ray Citigraphic apparatus when detecting the center of rotation and the tilt of the two-dimensional projection data input from the X-ray Citigraphic imaging apparatus. A physical phantom providing a horizontal axis, comprising: an outer cylinder; A first inner cylinder located inside the outer cylinder and having a center axis coincident with the center axis of the outer cylinder, the first inner cylinder being scanned with a vertical axis as a reference for measuring the center of rotation in the two-dimensional projection image; And a second portion positioned below the first inner cylinder and scanned with a vertical axis serving as a reference for measuring the inclination in the two-dimensional projection image while the center axis coincides with the center axis of the outer cylinder and the first inner cylinder. It provides a physical phantom comprising: an inner cylinder.

In a preferred embodiment, the outer cylinder is made of acrylic plastic, and the first inner cylinder and the second inner cylinder are made of aluminum or teflon.

In a preferred embodiment, the first inner cylinder has a top surface formed on the same surface as the top surface of the outer cylinder, the second inner cylinder is formed so that the top surface is in contact with the bottom surface of the first inner cylinder and the first inner cylinder It is provided to have a diameter larger than the diameter of the cylinder.

In a preferred embodiment, the outer cylinder has a diameter of 30 mm to 50 mm and a height of 45 mm to 60 mm.

In a preferred embodiment, the diameter of the first inner cylinder is 6 mm to 10 mm and the height is 20 mm to 30 mm.

In a preferred embodiment, the diameter of the second inner cylinder is 11 mm to 20 mm and the height is 4 mm to 8 mm.

The present invention has the following excellent effects.

First, according to the physical phantom according to the embodiment of the present invention, since the first inner cylinder and the second inner cylinder provide clear outlines as the vertical axis and the horizontal axis, respectively, in the two-dimensional projection image scanned by the X-ray Citigraphy apparatus, A state in which the rotation center of the X-ray Citigraphy apparatus is moved and an inclination of the X-ray CIT imaging apparatus can be easily and accurately detected.

1 is a perspective view showing a physical phantom according to an embodiment of the present invention.
2 is a cross-sectional view showing a cross section of the physical phantom of FIG.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

Hereinafter, the technical structure of the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

1 is a perspective view showing a physical phantom according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing a cross section of the physical phantom of FIG.

1 to 2, a physical phantom according to an embodiment of the present invention is displayed on a horizontal axis and a vertical axis in a two-dimensional projection image scanned by an X-ray Citigraphy apparatus, and is input by the X-ray Citi apparatus. The center of rotation and inclination of the projection data can be detected easily and accurately, and includes an outer cylinder 110, a first inner cylinder 120, and a second inner cylinder 130.

In addition, the X-ray Citigraphic imaging apparatus may scan two-dimensional projection data consisting of two-dimensional projection images while the X-ray source and the detector are rotated. In addition, the 2D projection data may be reconstructed into a 3D image through a 3D projection reconstruction technique.

In addition, the technique of correcting the center of rotation of the 2D projection data scanned by the X-ray Citigraphic apparatus, for example, the center point of the central axis of the X-ray Citigraphic apparatus does not coincide with the rotation center of the physical phantom, or moved during scanning It can be corrected by software to obtain a clear three-dimensional image by correcting when reconstructing the three-dimensional image, or by arranging the X-ray source and detector of the X-ray Citigraphic apparatus, the center point of the central axis of the X-ray Citigraphic apparatus is It may be corrected by hardware that does not match the center of rotation of the phantom or is moved during scanning.

In addition, the technique of correcting the inclination of the two-dimensional projection data scanned by the X-ray Citigraphic apparatus, for example, detects the boundary of the physical phantom in each of the two-dimensional projection images constituting the two-dimensional projection data, the x-axis and After calculating the angle of inclination of the boundary line on the y-axis, the two-dimensional projection data may be corrected by rotationally converting the inverse of the inclination angle.

The outer cylinder 110 is to form an outer surface, it may be made of a plastic material, preferably is made of acrylic plastic (acrylic plastic).

In addition, the outer cylinder 110 may have a diameter of 30 mm to 50 mm, and is preferably formed to have a diameter of 40 mm.

In addition, the height of the outer cylinder 110 may be provided with a 45 mm to 60 mm, preferably may be formed to have a height of 52 mm.

In addition, the outer cylinder 110 is not clearly seen in the two-dimensional image scanned by the X-ray Citigraphic apparatus compared to the first inner cylinder 120 and the second inner cylinder 130 to be described later.

The first inner cylinder 120 is formed inside the outer cylinder 110, the central axis is formed to coincide with the central axis of the outer cylinder 110, the two-dimensional scanned by the X-ray Citigraphy In the projected image, it is scanned along the vertical axis, which is the reference for measuring the center of rotation.

In addition, the first inner cylinder 120 may be made of a material having a high density that does not easily transmit X-rays, and is preferably provided to have a higher density than the outer cylinder 110. In addition, the first inner cylinder 120 may be formed of aluminum or teflon. In addition, an upper surface of the first inner cylinder 120 may be formed on the same surface as the upper surface of the outer cylinder 110.

In addition, the first inner cylinder 120 is preferably formed to have a height larger than the diameter, the first inner cylinder 120 is a vertical axis in the two-dimensional projection image scanned by the X-ray Citigraphy apparatus May appear.

In addition, the diameter of the first inner cylinder 120 may be provided with 6 mm to 10 mm, preferably may have a diameter of 8 mm. In addition, the height of the first inner cylinder 120 may be provided with 20 mm to 30 mm, preferably has a height of 26 mm.

In addition, when the center of X-ray source and detector of the X-ray Citigraphy apparatus and the center of rotation of the 2D projection data do not coincide with each other and are spaced apart by a predetermined distance, the 2D projection is performed. Since the first inner cylinder 120 is scanned in the form of a vertical axis in a two-dimensional projection image forming data, the distance and the position where the rotation center is moved by using the scanned state and position of the first inner cylinder 120. Can be easily detected and corrected.

The second inner cylinder 130 is formed to be located below the first inner cylinder 120 in the outer cylinder 110, the central axis of the outer cylinder 110 and the first inner cylinder. It is provided to coincide with the central axis of 120, and the 2D projection image scanned by the X-ray Citigraphy apparatus scans a horizontal axis that is a reference for measuring tilt.

In addition, the second inner cylinder 130 may be made of a material having a high density so that the X-rays do not easily transmit, it may be provided with aluminum or Teflon in the same way as the first inner cylinder 120.

In addition, the second inner cylinder 130 is formed so that the upper surface is in contact with the bottom surface of the first inner cylinder 120, at this time, the first inner cylinder 120 and the second inner cylinder 130 It may be bonded or bonded.

In addition, the second inner cylinder 130 is provided to have a diameter larger than the diameter of the first inner cylinder 120, the diameter of the second inner cylinder 130 may be provided with 11 mm to 20 mm. , Preferably has a diameter of 15 mm. In addition, the height of the second inner cylinder 130 may be provided with 4 mm to 8 mm, preferably, has a height of 6 mm.

In addition, the second inner cylinder 130 provides a horizontal axis formed of straight lines in the two-dimensional projection image scanned by the X-ray Citigraphic apparatus, and in particular, the bottom surface 131 of the second inner cylinder 130 is It can appear on the horizontal axis.

In addition, when the 2D projection data scanned by the X-ray Citigraphy apparatus is scanned at an inclined angle, the horizontal axis of the second inner cylinder 130 is scanned in the 2D projection image constituting the 2D projection data. Therefore, the inclination of the two-dimensional projection data can be easily detected and corrected by calculating the inclination angle of the horizontal axis.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

110: outer cylinder 120: first inner cylinder
130: second internal cylinder

Claims (6)

A physical phantom which provides a vertical axis and a horizontal axis as a reference in the two-dimensional projection image scanned by the X-ray Citigraphic apparatus when detecting the rotational center and the tilt of the two-dimensional projection data input by the X-ray Citigraphic imaging apparatus.
Outer cylinder;
A first inner cylinder located inside the outer cylinder and having a center axis coincident with the center axis of the outer cylinder, the first inner cylinder being scanned with a vertical axis as a reference for measuring the center of rotation in the two-dimensional projection image; And
A second inner portion positioned below the first inner cylinder and scanned with a vertical axis as a reference for measuring the inclination in the two-dimensional projection image while a central axis coinciding with the central axis of the outer cylinder and the first inner cylinder Cylinder; Physical phantom comprising a.
The method of claim 1,
Wherein the outer cylinder is made of acrylic plastic, and the first inner cylinder and the second inner cylinder are made of aluminum or teflon.
The method of claim 2,
The first inner cylinder has a top surface formed on the same surface as the top surface of the outer cylinder, and the second inner cylinder has a diameter larger than the diameter of the first inner cylinder while the top surface is formed to contact the bottom surface of the first inner cylinder. Physical phantom characterized in that it is provided to have.
The method of claim 3,
The diameter of the outer cylinder is 30 mm to 50 mm, the physical phantom, characterized in that the height is 45 mm to 60 mm.
5. The method of claim 4,
The physical diameter of the first inner cylinder is 6 mm to 10 mm, the height is 20 mm to 30 mm.
6. The method of claim 5,
The diameter of the second inner cylinder is 11 mm to 20 mm, the physical phantom, characterized in that the height is 4 mm to 8 mm.

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