CT resolution uniformity evaluation die body

Abstract

The utility model discloses a CT resolution uniformity assessment die body, comprising a die body main body, the die body main body is cylindrical, the die body main body is sequentially provided with nine layers of modules from top to bottom, the nine layers of modules are divided into three modules, the first layer of modules to the third layer of modules are first modules for assessing tangential resolution, and the fourth layer of modules are second modules for assessing tangential resolution. The modules from the fourth layer to the sixth layer are second modules for evaluating the radial resolution, the modules from the seventh layer to the ninth layer are third modules for evaluating the contrast, and resolution line pairs parallel to the diameter of a module main body are uniformly arranged on the first module; resolution line pairs perpendicular to the diameter of the module body are evenly arranged on the second module, and round filler is evenly arranged on the third module. According to the utility model, on one hand, the resolution uniformity motif can be used for evaluating the spatial resolution uniformity of an image, and on the other hand, the advantages and disadvantages of a resolution improvement algorithm can be evaluated.

Description

TECHNICAL FIELD

[0001] The utility model relates to medical metrology detection equipment technical field especially, relates to a CT resolution uniformity evaluation phantom. BACKGROUND

[0002] CT image resolution is an important index of evaluating image quality, including tangential resolution, radial resolution and z-direction resolution.

[0003] The spatial resolution of an image refers to the ability of the image to distinguish adjacent objects. It is usually evaluated in two orthogonal directions, namely in-plane (x-y) resolution and cross-sectional (z-axis) resolution. The in-plane spatial resolution is further divided into two orthogonal direction resolutions, namely radial and azimuthal resolution. The radial direction is along the line connecting the focal spot of the x-ray source and the rotation center, and the azimuthal direction is perpendicular to the radial direction. The radial spatial resolution is mainly determined by the size and shape of the focal spot, the detector aperture, the scanning mode and the reconstruction algorithm. The azimuthal spatial resolution is largely dependent on the number of projections, the size of the x-ray source, the distance between the reconstruction point and the rotation center, and the detector aperture. Therefore, an effective way to increase the azimuthal spatial resolution is to increase the number of projection samples.

[0004] Several classic resolution evaluation methods include line pairs, MTF curves and slice sensitivity curves.

[0005] Line pairs are a classic method for evaluating in-plane spatial resolution. Here, line pairs refer to black and white stripes. The classic line pair phantom is the phantom, which contains 21 line pairs with different stripe widths. The higher the resolution of the CT system, the narrower the line pairs that can be seen on the corresponding image. In this evaluation method, the resolution refers to the number of line pairs that can be distinguished per cm.

[0006] The modulation transfer function (MTF) is the ratio of output modulation to input modulation. The MTF of a system can be obtained by calculating the Fourier transform function of the point spread function (PSF) or the line spread function (LSF). The point spread function and the line spread function are transmission characteristic functions of the CT system, which describe the characteristics of the system.

[0007] The Z-direction spatial resolution is usually described by a slice sensitivity profile, which is usually measured with small beads or thin discs. The slice sensitivity profile (SSP) is usually described by two parameters, the full width at half maxima (FWHM) and the full width at 0.1 maximum (FWTM), representing the distance between the two points where the intensity of the SSP peak is 50% and 10%, respectively.

[0008] Phantoms are important tools for evaluating image resolution. However, existing phantoms are more concerned with measuring image resolution rather than the uniformity of image resolution. Therefore, a phantom is needed to evaluate the uniformity of the tangential and radial resolutions of a system, and more comprehensively evaluate the resolution of the system. Utility model content

[0009] The utility model aims at providing a CT resolution uniformity evaluation phantom, solves the problem that the existing phantom cannot comprehensively evaluate the resolution of the system.

[0010] To solve the above technical problems, the utility model adopts the technical scheme that:

[0011] A CT resolution uniformity evaluation phantom, comprising a phantom main body, the phantom main body is cylindrical, 9 layers of modules are sequentially arranged from top to bottom on the phantom main body, and the 9 layers of modules are divided into three modules, the first layer of modules to the third layer of modules are a first module group for evaluating tangential resolution, the fourth layer of modules to the sixth layer of modules are a second module group for evaluating radial resolution, and the seventh layer of modules to the ninth layer of modules are a third module group for evaluating contrast, resolution line pairs parallel to the diameter of the module main body are uniformly arranged on the first module group, resolution line pairs perpendicular to the diameter of the module main body are uniformly arranged on the second module group, and circular fillers are uniformly arranged on the third module group.

[0012] Further, the cross-sectional diameter of the phantom main body is 150mm, and the height is 150mm.

[0013] Further, the length of the line pairs on the first module group and the second module group is 5mm, and the height is 2mm.

[0014] Further, three kinds of resolution line pairs are uniformly and spacedly arranged on the first layer of modules and the fourth layer of modules, each kind of resolution line pair is 5 teeth, the center distance of the three kinds of resolution line pairs from the module center is 55mm, the data of the three kinds of resolution line pairs is as follows: 18lp / cm, tooth width is 0.28mm; 16lp / cm, tooth width is 0.31mm; 14lp / cm, tooth width is 0.36mm, and the central angle between adjacent resolution line pairs is 30 degrees.

[0015] Further, 2 resolution line pairs are uniformly and spacedly arranged on the second layer module and the fifth layer module, each resolution line pair has 5 teeth, the center distance of the two resolution line pairs is 35mm from the module center, and the data of the two resolution line pairs are: 12lp / cm, tooth width is 0.42mm; 10lp / cm, tooth width is 0.5mm, and the central angle between adjacent resolution line pairs is 45 degrees.

[0016] Further, 2 resolution line pairs are uniformly and spacedly arranged on the third layer module and the sixth layer module, each resolution line pair has 5 teeth, the center distance of the two resolution line pairs is 15mm from the module center, and the data of the three resolution line pairs are: 8lp / cm, tooth width is 0.63mm; 4lp / cm, tooth width is 1.25mm, and the central angle between adjacent resolution line pairs is 45 degrees.

[0017] Further, 3 circular fillers are uniformly and spacedly arranged on the seventh layer module, the center distance of the three circular fillers is 55mm from the module center, the diameters of the three circular fillers are 15mm, 9mm and 4mm respectively, and the contrast ratios are all 1.0%, and the central angle between adjacent circular fillers is 30 degrees.

[0018] Further, 3 circular fillers are uniformly and spacedly arranged on the eighth layer module, the center distance of the three circular fillers is 35mm from the module center, the diameters of the three circular fillers are 15mm, 9mm and 4mm respectively, and the contrast ratios are all 0.5%, and the central angle between adjacent circular fillers is 30 degrees.

[0019] Further, 3 circular fillers are uniformly and spacedly arranged on the ninth layer module, the center distance of the three circular fillers is 15mm from the module center, the diameters of the three circular fillers are 15mm, 9mm and 4mm respectively, and the contrast ratios are all 0.3%, and the central angle between adjacent circular fillers is 45 degrees.

[0020] Beneficial effects:

[0021] The resolution uniformity model in the utility model can be used for evaluating the spatial resolution uniformity of an image on one hand, and can also evaluate the advantages and disadvantages of a resolution improvement algorithm on the other hand. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a whole structure schematic view of the utility model.

[0023] Figure 2 It is a sectional view of the first layer module in the utility model.

[0024] Figure 3It is the cross-sectional view of the second layer module in the utility model;

[0025] Figure 4 It is the cross-sectional view of the third layer module in the utility model;

[0026] Figure 5 It is the cross-sectional view of the fourth layer module in the utility model;

[0027] Figure 6 It is the cross-sectional view of the fifth layer module in the utility model;

[0028] Figure 7 It is the cross-sectional view of the sixth layer module in the utility model;

[0029] Figure 8 It is the cross-sectional view of the seventh layer module in the utility model;

[0030] Figure 9 It is the cross-sectional view of the eighth layer module in the utility model;

[0031] Figure 10 It is the cross-sectional view of the ninth layer module in the utility model.

[0032] Marked number in the drawing: 1, first layer module;2, second layer module;3, third layer module;4, fourth layer module;5, fifth layer module;6, sixth layer module;7, seventh layer module;8, eighth layer module;9, ninth layer module. DETAILED DESCRIPTION

[0033] In the description of the embodiment, it needs to be explained that the orientation or position relationship indicated by the terms "upper", "lower" and the like is based on the orientation or position relationship shown in the drawing, or is the orientation or position relationship when the utility model product is usually placed, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model. In addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection" and the like should be understood broadly, for example, can be fixedly connected, can be detachably connected, or can be integrally connected;Can be directly connected, can be indirectly connected through an intermediate medium, or can be connected inside two elements. For ordinary skilled persons in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0034] In addition, unless otherwise specified, the components used in the following embodiments are all existing components, and the corresponding connection mode can also be realized by conventional technical means, which will not be described one by one in this application. The utility model will be further described in detail in combination with the drawings and specific embodiments.

[0035] Example 1

[0036] A CT resolution uniformity evaluation phantom, such as Figure 1 As shown, the device includes a cylindrical body with a cross-sectional diameter of 150 mm and a height of 150 mm. The body comprises nine modules arranged from top to bottom, divided into three modules: the first module (modules 1 to 3) evaluates tangential resolution; the fourth module (modules 4 to 6) evaluates radial resolution; and the seventh module (modules 7 to 9) evaluates contrast. The first module has uniformly arranged pairs of resolution lines parallel to the diameter of the body, while the second module has uniformly arranged pairs of resolution lines perpendicular to the diameter. The line pairs in both modules are 5 mm long and 2 mm high. The third module has uniformly arranged circular fillers.

[0037] Specifically, the CT resolution uniformity evaluation phantom in this embodiment is equipped with a first module and a second module for evaluating tangential and radial resolution uniformity, and a third module for evaluating contrast pair uniformity. Through the layered design, the performance of the imaging system in different directions and aspects can be evaluated in detail. The height of the line pair, i.e. the thickness, is only 2mm, which can avoid the obscuring of some details of resolution non-uniformity due to excessive layer thickness.

[0038] Multiple line pair combinations with different resolutions are set in the first and second modules. This diverse line pair configuration allows for a more comprehensive evaluation of the imaging system's performance at different resolution levels. Different resolution line pairs can cover varying degrees of detail, enabling the detection of the imaging system's uniformity across different resolution levels and identifying potential resolution abrupt changes or non-uniform areas. Furthermore, the uniform distribution of line pairs allows for evaluation of resolution uniformity in all directions, avoiding evaluation blind spots caused by uneven line pair distribution and comprehensively detecting the resolution uniformity of the imaging system across the entire plane.

[0039] Specifically, the three-layer module design is as follows: Figures 2 to 4 As shown.

[0040] First-level module 1, as shown Figure 2 As shown, three types of resolution line pairs are evenly spaced, each with 5 teeth. The center distance of the three types of resolution line pairs from the center of the module is 55mm. The data of the three types of resolution line pairs are: 18lp / cm (black), tooth width 0.28mm; 16lp / cm (yellow), tooth width 0.31mm; 14lp / cm (green), tooth width 0.36mm. There are 4 of each type of line pair, for a total of 12 line pairs. The central angle between adjacent resolution line pairs is 30 degrees.

[0041] The second layer module 2 is shown in FIG. 2, in which two resolution line pairs are uniformly spaced, each of which has 5 teeth, the center distance of the two resolution line pairs is 35mm from the module center, and the data of the two resolution line pairs are: 12lp / cm (blue), with a tooth width of 0.42mm; 10lp / cm (red), with a tooth width of 0.5mm. Each line pair has 4, and there are a total of 8 line pairs. The center angle between adjacent resolution line pairs is 45 degrees. Figure 3

[0042] The third layer module 3 is shown in FIG. 3, in which two resolution line pairs are uniformly spaced, each of which has 5 teeth, the center distance of the two resolution line pairs is 15mm from the module center, and the data of the three resolution line pairs are: 8lp / cm (purple), with a tooth width of 0.63mm; 4lp / cm (green), with a tooth width of 1.25mm. Each line pair has 4, and there are a total of 8 line pairs. The center angle between adjacent resolution line pairs is 45 degrees. Figure 4

[0043] The second module is shown in FIG. 4, in which the fourth layer module 4 is similar to the first layer module 1, the fifth layer module 5 is similar to the second layer module 2, and the sixth layer module 6 is similar to the third layer module 3. The difference is that the resolution line pairs of the second module are perpendicular to the resolution line pairs of the first module. Figures 5 to 7 In the third module, by setting fillers with different diameters and three layers with different contrasts, the performance of the imaging system under different contrast conditions can be more carefully investigated, the imaging ability of the imaging system for objects of different sizes and contrasts can be understood, and the contrast uniformity of the imaging system can be more comprehensively evaluated. The uniform distribution of the fillers can comprehensively evaluate the resolution uniformity of the imaging system for objects of different contrasts and sizes in the entire plane, and determine whether there are some areas where the imaging effect for objects of a specific contrast or size is poor.

[0044] Specifically, the design of the three-layer module is shown in FIG. 5.

[0045] Figures 8 to 10

[0046] The seventh layer module 7 is shown in FIG. 7, in which three circular fillers are uniformly spaced, the center distance of the three circular fillers is 55mm from the module center, the diameters of the three circular fillers are 15mm, 9mm and 4mm respectively, and the contrast is 1.0%. The center angle between adjacent circular fillers is 30 degrees. Figure 8

[0047] The eighth layer module 8 is shown in FIG. 8, in which three circular fillers are uniformly spaced, the center distance of the three circular fillers is 55mm from the module center, the diameters of the three circular fillers are 15mm, 9mm and 4mm respectively, and the contrast is 1.0%. The center angle between adjacent circular fillers is 30 degrees. Figure 9 ​​​​​As shown, three kinds of circular fillers are uniformly spaced, the centers of the three kinds of circular fillers are 35mm away from the center of the module, the diameters of the three kinds of circular fillers are 15mm, 9mm and 4mm respectively, and the contrast of each kind of circular filler is 0.5%, and the central angle between adjacent circular fillers is 30 degrees.

[0048] The ninth layer module 9 is as shown in the figure Figure 10 As shown, three kinds of circular fillers are uniformly spaced, the centers of the three kinds of circular fillers are 15mm away from the center of the module, the diameters of the three kinds of circular fillers are 15mm, 9mm and 4mm respectively, and the contrast of each kind of circular filler is 0.3%, and the central angle between adjacent circular fillers is 45 degrees.

[0049] Although the embodiments of the utility model are described in the specification, these embodiments are only as a hint, should not limit the protection scope of the utility model. Various omissions, substitutions and changes within the scope of the utility model should be contained in the protection scope of the utility model.

Claims

1. A phantom for CT resolution uniformity assessment, characterized in that: The body includes a main body, the main body is cylindrical, 9 layers of modules are sequentially arranged from top to bottom, and the 9 layers of modules are divided into three modules, the first layer of module to the third layer of module are a first module group for evaluating tangential resolution, the fourth layer of module to the sixth layer of module are a second module group for evaluating radial resolution, and the seventh layer of module to the ninth layer of module are a third module group for evaluating contrast, resolution line pairs parallel to the diameter of the main body are uniformly arranged on the first module group, resolution line pairs perpendicular to the diameter of the main body are uniformly arranged on the second module group, and circular fillers are uniformly arranged on the third module group.

2. The CT resolution uniformity assessment phantom of claim 1, wherein: The cross-sectional diameter of the main body is 150 mm, and the height is 150 mm.

3. The CT resolution uniformity assessment phantom of claim 1, wherein: The length of the line pairs on the first module group and the second module group is 5 mm, and the height is 2 mm.

4. The CT resolution uniformity assessment phantom of claim 1, wherein: Three kinds of resolution line pairs are uniformly and spacedly arranged on the first layer of module and the fourth layer of module, each kind of resolution line pair is 5 teeth, the center distance of the three kinds of resolution line pairs from the module center is 55 mm, and the data of the three kinds of resolution line pairs are as follows: 18 lp / cm, tooth width is 0.28 mm; 16 lp / cm, tooth width is 0.31 mm; 14 lp / cm, tooth width is 0.36 mm, and the central angle between adjacent resolution line pairs is 30 degrees. Two kinds of resolution line pairs are uniformly and spacedly arranged on the second layer of module and the fifth layer of module, each kind of resolution line pair is 5 teeth, the center distance of the two kinds of resolution line pairs from the module center is 35 mm, and the data of the two kinds of resolution line pairs are as follows: 12 lp / cm, tooth width is 0.42 mm; 10 lp / cm, tooth width is 0.5 mm, and the central angle between adjacent resolution line pairs is 45 degrees.

5. The CT resolution uniformity assessment phantom of claim 1, wherein: Two kinds of resolution line pairs are uniformly and spacedly arranged on the third layer of module and the sixth layer of module, each kind of resolution line pair is 5 teeth, the center distance of the two kinds of resolution line pairs from the module center is 15 mm, and the data of the three kinds of resolution line pairs are as follows: 8 lp / cm, tooth width is 0.63 mm; 4 lp / cm, tooth width is 1.25 mm, and the central angle between adjacent resolution line pairs is 45 degrees.

6. The CT resolution uniformity assessment phantom of claim 1, wherein: Three kinds of circular fillers are uniformly and spacedly arranged on the seventh layer of module, the center distance of the three kinds of circular fillers from the module center is 55 mm, the diameters of the three kinds of circular fillers are 15 mm, 9 mm and 4 mm respectively, the contrast of the three kinds of circular fillers is 1.0%, and the central angle between adjacent circular fillers is 30 degrees.

7. The CT resolution uniformity assessment phantom of claim 1, wherein: Three kinds of circular fillers are uniformly and spacedly arranged on the eighth layer of module, the center distance of the three kinds of circular fillers from the module center is 35 mm, the diameters of the three kinds of circular fillers are 15 mm, 9 mm and 4 mm respectively, the contrast of the three kinds of circular fillers is 0.5%, and the central angle between adjacent circular fillers is 30 degrees.

8. The CT resolution uniformity assessment phantom of claim 1, wherein: Three kinds of circular fillers are uniformly and spacedly arranged on the ninth layer of module, the center distance of the three kinds of circular fillers from the module center is 15 mm, the diameters of the three kinds of circular fillers are 15 mm, 9 mm and 4 mm respectively, the contrast of the three kinds of circular fillers is 0.3%, and the central angle between adjacent circular fillers is 45 degrees.

9. The CT resolution uniformity assessment phantom of claim 1, wherein: ​

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