Phantom and X-ray imaging device for measuring bone density in X-ray imaging device

Abstract

The present invention provides a phantom used for measuring bone density of an X-ray imaging device and an X-ray imaging device, and relates to the technical field of bone density measurement. The phantom used for measuring bone density of an X-ray imaging device comprises a phantom body; the phantom body has a plurality of steps, and the distances between the top surfaces of the plurality of steps and the bottom surface of the phantom body are different. The X-ray imaging device comprises an X-ray imaging device body and a phantom used for measuring bone density of an X-ray imaging device. The technical effect that a conventional clinical X-ray imaging device can measure bone density is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of bone density measurement, and in particular to a phantom and an X-ray imaging device used for measuring bone density of an X-ray imaging device. Background Art

[0002] Bone mineral density (BMD) is the most important and most commonly used quantitative index for clinical evaluation of osteoporosis and bone strength, and is also the main basis for the prevention and treatment of osteoporosis. Low bone density is currently recognized as the main risk factor for brittle fractures. For every 1 standard deviation (SD) decrease in bone density, the risk of fracture increases by 1.5 to 3.0 times. The currently recognized method for measuring bone density is dual-energy X-ray absorptiometry (DXA). DXA uses two different energy X-rays (one is 40kev and the other is 80kev) to pass through human bones. The attenuation and absorption are different. After computer processing, the mineral content in human bones is obtained. The area BMD obtained by DXA is the current gold standard for bone testing and is widely used in clinical medicine and epidemiological research. DXA was first used by Jacobson in the 1960s and gradually became widely used in the 1980s. The "gold standard" for clinical diagnosis of osteoporosis is the standard proposed by the World Health Organization (WHO) in 1994 (based on the peak bone density in the normal population, T value <-2.5 standard deviations). DXA is the main technology for measuring bone density ( Figure 1 , Figure 2 ), which is simple, fast, has low radiation, is easy to operate and has market advantages, but requires special DXA bone density equipment and is expensive.

[0003] There are application restrictions for medical institutions that are not equipped with DXA bone densitometers or certain specific groups (children, pregnant women, and patients with external fixation after orthopedic surgery). At present, there are few DXA devices in China, and they cannot be widely used in clinical practice. In addition, for some sick children or patients after orthopedic internal fixation surgery, if they need to understand the bone density or bone strength, they still need to do a special DXA bone density test after completing routine clinical X-ray imaging examinations, which increases the radiation hazards and medical expenses of patients.

[0004] Therefore, providing a phantom and an X-ray imaging device for use in bone density measurement by an X-ray imaging device, which enables conventional clinical X-ray imaging devices to measure bone density, has become an important technical problem to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a phantom and an X-ray imaging device for measuring bone density using an X-ray imaging device, so as to solve the technical problem in the prior art that conventional clinical X-ray imaging devices cannot measure bone density.

[0006] In a first aspect, an embodiment of the present invention provides a phantom for use in bone density measurement of an X-ray imaging device, including a phantom body;

[0007] The phantom body has a plurality of steps, and the distances between the top surfaces of the plurality of steps and the bottom surface of the phantom body are different.

[0008] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the phantom body is in a stepped shape.

[0009] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the thickness of each step gradually increases from the bottom to the top of the phantom body.

[0010] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein, from the bottom to the top of the phantom body, the distance between the top surface of each step and the bottom surface of the phantom body gradually increases.

[0011] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the number of the steps is not less than two.

[0012] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the material of the phantom body is a material equivalent to human bone density.

[0013] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the material of the phantom body is hydroxyapatite.

[0014] In combination with the first aspect, an embodiment of the present invention provides a possible implementation of the first aspect, wherein the material of the phantom body is dipotassium hydrogen phosphate.

[0015] In combination with the first aspect, the embodiment of the present invention provides a possible implementation of the first aspect, wherein the maximum equivalent bone density value of the step on the phantom body is not less than 2.4 g / cm 2 .

[0016] In a second aspect, an embodiment of the present invention provides an X-ray imaging device, including an X-ray imaging device body and a phantom used for measuring bone density of the X-ray imaging device.

[0017] Beneficial effects:

[0018] An embodiment of the present invention provides a phantom for measuring bone density of an X-ray imaging device, comprising a phantom body; the phantom body is provided with a plurality of steps, and the distances between the top surfaces of the plurality of steps and the bottom surface of the phantom body are different.

[0019] Specifically, the phantom body is used in conjunction with routine clinical X-ray imaging examinations. When in use, the phantom body and the bone part to be irradiated are placed in the same irradiation field. The height of each step on the phantom body is known. The difference in ray attenuation after X-rays pass through objects of different densities is used for quantitative calculation, and the mathematical calculation relationship between X-ray attenuation and bone density is converted to calculate the bone density of the target area. In this way, bone density measurement and collection are completed simultaneously when the patient undergoes routine clinical imaging X-ray examinations, without increasing the patient's additional X-ray examination radiation dose.

[0020] The present invention provides an X-ray imaging device, including an X-ray imaging device body and a phantom used for bone density measurement of the X-ray imaging device. The X-ray imaging device has the above advantages compared with the prior art, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a phantom used for bone density measurement of an X-ray imaging device provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of a phantom used for bone density measurement by an X-ray imaging device according to an embodiment of the present invention.

[0024] icon:

[0025] 100 - phantom body;

[0026] 110 - stairs. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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 are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0032] See also Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a phantom for measuring bone density of an X-ray imaging device, including a phantom body 100; the phantom body 100 has a plurality of steps 110, and the distances between the top surfaces of the plurality of steps 110 and the bottom surface of the phantom body 100 are different.

[0033] Specifically, the phantom body 100 is used in conjunction with routine clinical X-ray imaging examinations. When in use, the phantom body 100 and the bone part to be irradiated are placed in the same irradiation field. The height of each step 110 on the phantom body 100 is known. The difference in ray attenuation after X-rays pass through objects of different densities is used for quantitative calculation, and the mathematical calculation relationship between X-ray attenuation and bone density is converted to calculate the bone density of the target area. In this way, when the patient undergoes routine clinical imaging X-ray examinations, the bone density measurement and collection is completed synchronously, without increasing the patient's additional X-ray examination radiation dose. At the same time, for certain specific populations, such as children or pregnant women, the bone density of a specific area can also be obtained when necessary while taking good radiation protection measures. For example, some children need to irradiate wrist X-rays to clarify the bone age. If the phantom provided in this embodiment is used for bone density measurement of X-ray imaging equipment, the bone density of the child can be obtained at the same time.

[0034] Specifically, especially for some patients after orthopedic internal and external fixation surgery, the phantom used for bone density measurement by X-ray imaging equipment provided in this embodiment can solve clinical dilemmas. For example, patients undergoing osteotomy and lengthening surgery all need metal external fixators as limb extenders with a pulling effect. Affected by metal artifacts of the external fixator, the current bone density meter DXA cannot evaluate the density and strength of the extended new bone. When to remove the external fixator is a difficult problem for orthopedic physicians. If it is removed too early, there is a risk of brittle fracture of the new bone, while if it is removed too late, the risk of infection such as exudation and swelling of the patient's nail channel will increase, leading to treatment failure, and increasing the pain and inconvenience of the patient wearing the external fixator. Therefore, it is extremely important and necessary to evaluate the bone strength of the extended new bone to improve the clinical treatment effect and alleviate the pain of patients. The stepped hydroxyapatite density phantom is used to quantitatively depict the attenuation and absorption of X-rays passing through materials of different densities, thereby realizing the function of calculating bone density by digital X-ray images of single-energy rays, which is not interfered by metal artifacts, and provides necessary qualitative and quantitative data for orthopedic physicians, which is of great benefit to the formulation of their treatment plans, the selection of surgical procedures, the judgment of prognosis, and the follow-up of efficacy.

[0035] Specifically, after X-rays pass through objects of different densities, the rays will be attenuated, and for the same material, the attenuation changes linearly, and the heights of the multiple steps 110 are known. When the X-rays irradiate the steps 110 of the phantom body 100, the X-ray imaging device receives the attenuated X-rays, so that the mathematical calculation relationship between the X-ray attenuation and the density of the phantom body 100 can be converted, and then the mathematical calculation relationship between the X-ray attenuation and the bone density can be converted.

[0036] Among them, the density evaluation analysis method is: μROI = σX·ρHA + βX. The above equation lists the density analysis evaluation method of parameters σX and βX. Among them, μROI is the pixel value in the region of interest (ROI) of the reference material or unknown material; ρHA is the density of HA in the ROI of the measured material; σX is an imaging technology-specific parameter that defines the response of the digital X-ray machine to HA; βX is an imaging technology-specific parameter with X-ray attenuation absorption value measurement characteristics. It should be noted that the pixel values ​​involved in the formula are all values ​​after soft tissue density silhouette.

[0037] Among them, the influence of soft tissue components of different thicknesses on bone density measurement was analyzed. In order to standardize the degree of influence of thickness increase on bone density, a fixed thickness of organic glass plate was used as a soft tissue substitute, because the attenuation degree of X-ray passing through organic glass is the same as that of human soft tissue. The DXA quality control phantom was placed on organic glass plates of different thicknesses (1cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm) and filmed under the same conditions. The stepped phantom was placed next to the glass plate and the quality control phantom, and then the changes in the bone density values ​​of the corresponding quality control phantoms were calculated.

[0038] Among them, by setting a plurality of steps 110 of different heights, the accuracy of the mathematical calculation relationship between X-ray attenuation and the density of the phantom body 100 can be improved. For example, by using the lowest step 110 and the highest step 110 for calculation, the first conversion coefficient between the distance of the phantom body 100 between the lowest step 110 and the highest step 110 and the X-ray attenuation can be obtained. By using the lowest step 110 and the second highest step 110 for calculation, the second conversion coefficient between the distance of the phantom body 100 between the lowest step 110 and the second highest step 110 and the X-ray attenuation can be obtained. By analogy, the more steps 110 there are, the more conversion coefficients there are, and the more accurate the conversion system finally obtained is. Then, the mathematical calculation relationship between the density and thickness of the phantom body 100 and the X-ray attenuation is quantitatively calculated as an objective reference, and the bone density conversion can be performed by measuring the pixel density value (i.e., the X-ray attenuation absorption value) of the corresponding human bone part.

[0039] It should be noted that, in this embodiment, the “height of the step 110 ” refers to: the distance between the upper surface of the step 110 and the bottom surface of the phantom body 100 ; and the “thickness of the step 110 ” in this embodiment refers to: the distance between the top surface of the step 110 and the top surface of the next lower step 110 .

[0040] See also Figure 1 and Figure 2 As shown, in an optional solution of this embodiment, the phantom body 100 is in a stepped shape.

[0041] Specifically, from the bottom to the top of the phantom body 100 , the distance between the top surface of each step 110 and the bottom surface of the phantom body 100 gradually increases.

[0042] Specifically, the phantom body 100 is arranged in a stepped shape, which is convenient for medical personnel to use, and when in use, the X-ray attenuation conditions at different equivalent bone densities of the phantom body 100 can be clearly known.

[0043] Specifically, on an X-ray film, the lower the equivalent bone density of the phantom body 100 is, the darker it is, and the higher the equivalent bone density is, the brighter it is.

[0044] in, Figure 2 The rectangular blocks with different brightness on the middle right side are images after the X-rays pass through the phantom body 100 , and the brighter the area, the thicker the phantom body 100 .

[0045] See also Figure 1 and Figure 2 As shown, in an optional solution of this embodiment, the thickness of each layer of steps 110 gradually increases from the bottom to the top of the phantom body 100 .

[0046] Specifically, the thickness of each step 110 gradually increases from bottom to top to eliminate the interference of the air between the light source of the X-ray imaging device and each step 110. By increasing the thickness of each step 110, the thickness of the air between each step 110 and the light source of the X-ray imaging device is equivalent to the same, and after removing the thickness of the equivalent air from each step 110, its height is an integer multiple of the height of the first step 110 to facilitate subsequent calculations.

[0047] Specifically, the height of the first step 110 is H1, the height of the second step 110 is 2H1+a1, the height of the third step 110 is 3H1+a2, and so on, wherein a1, a2, ... are the increase amounts of each step 110, and the purpose is to eliminate the interference of the air between the light source of the X-ray imaging device and each step 110, so as to ensure that the attenuation of the X-ray in the air between each step 110 and the light source of the X-ray imaging device is equivalent.

[0048] See also Figure 1 and Figure 2 As shown, in an optional solution of this embodiment, the number of steps 110 is not less than two.

[0049] Specifically, the number of the steps 110 may be three, four, or five, etc. The greater the number of the steps 110 , the more accurate the measurement result.

[0050] In an optional solution of this embodiment, the material of the phantom body 100 is a material equivalent to human bone density.

[0051] Specifically, the phantom body 100 is made of a material equivalent to human bone density, so that the density of the phantom body 100 is close to or equal to the density of human bones.

[0052] In an optional solution of this embodiment, the material of the phantom body 100 is hydroxyapatite.

[0053] Specifically, the phantom body 100 may be made of hydroxyapatite.

[0054] In an optional solution of this embodiment, the material of the phantom body 100 is dipotassium hydrogen phosphate.

[0055] Specifically, the phantom body 100 may be made of dipotassium hydrogen phosphate.

[0056] In an optional solution of this embodiment, the maximum equivalent bone density value of the steps on the phantom body 100 is not less than 2.4 g / cm 2 .

[0057] Specifically, the maximum equivalent bone density value of the step 110 on the phantom body 100 is not less than 2.4 g / cm 2 , which can ensure the accuracy of calculation and the accuracy of the obtained human bone density values.

[0058] If this is not done, when the maximum bone density value of the human skeleton to be tested is greater than the maximum equivalent bone density value of the phantom body 100, the maximum bone density value of the human skeleton to be tested has no actual reference value, and it is impossible to determine whether it complies with the calculation formula of the phantom body 100, so the accuracy cannot be guaranteed.

[0059] At present, the commonly used X-ray equipment in clinical practice mainly includes digital X-ray imaging technology (Computed Radiography, CR) and direct digital X-ray imaging technology (Direct Radiography, DR), which emits single-energy X-rays through the tube of the X-ray machine, and uses the different absorption and attenuation of X-rays by different tissues of the human body to form images with different black and white contrasts on the screen or X-ray film. However, due to the X-ray scattering effect, it is impossible to accurately and quantitatively measure bones, and it is also impossible to eliminate the influence of soft tissue on bone density measurement. The phantom used for bone density measurement of X-ray imaging equipment provided in this embodiment provides a reference mark for bone density measurement by designing a fixed height step and a uniform material of equivalent hydroxyapatite bone density, and realizes the correction formula of the linear relationship between bone X-ray attenuation and bone density. The phantom used for bone density measurement of X-ray imaging equipment provided in this embodiment is placed next to the bone part to be measured, and the bone density can be measured on the clinical X-ray imaging equipment.

[0060] The phantom used for bone density measurement of X-ray imaging equipment provided in this embodiment can be carried out simultaneously with routine clinical X-ray examination items, without generating artifacts or interfering with the imaging effect, and at the same time can provide the bone density of the imaging part, solving the problem that DXA (Dual X-Ray Absorbtiometry) bone density examination is currently required in clinical practice, avoiding patients from receiving additional radiation doses while reducing the cost of examination and the cost of large instruments such as DXA bone densitometers purchased by hospitals. In addition, for some special populations, such as children and pregnant women, it was difficult to perform DXA examinations alone in the past, and the phantom used for bone density measurement of X-ray imaging equipment provided in this embodiment can also be used to obtain bone density during routine clinical X-ray examinations. For patients undergoing osteotomy and lengthening surgery in the orthopedic department, due to the influence of the metal external fixator, it was difficult to measure the density of the new bone in the lengthening area by DXA in the past. The stepped phantom designed by the patent of the present invention can also achieve the simultaneous acquisition of bone density values ​​when taking X-rays of the surgical site.

[0061] This embodiment provides an X-ray imaging device, including an X-ray imaging device body and a phantom used for measuring bone density of the X-ray imaging device.

[0062] Specifically, the X-ray imaging device has the above advantages compared with the prior art, which will not be elaborated here.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phantom for measuring bone density in an X-ray imaging device, characterized in that: include: phantom body(100); The phantom body (100) has a plurality of steps (110), and the distances between the top surfaces of the plurality of steps (110) and the bottom surface of the phantom body (100) are different; The phantom body (100) is in a stepped shape; From the bottom to the top of the phantom body (100), the thickness of each step (110) gradually increases, and the distance between the top surface of the step (110) and the top surface of the next lower step (110) is the thickness of the step (110); From the bottom to the top of the phantom body (100), the distance between the top surface of each step (110) and the bottom surface of the phantom body (100) gradually increases, and the distance between the top surface of each step (110) and the bottom surface of the phantom body (100) is the height of each step (110). The height of the first step is H1, the height of the second step is 2H1+a1, the height of the third step is 3H1+a2, and so on, wherein a1, a2, ... are the increase of each step (110), and are used to eliminate the interference of air between the light source of the X-ray imaging device and each step (110), so that the attenuation of the X-ray in the air between each step (110) and the light source of the X-ray imaging device is equivalent.

2. The phantom for measuring bone density of an X-ray imaging device according to claim 1, characterized in that: The material of the phantom body (100) is a material equivalent to human bone density.

3. The phantom for measuring bone density in an X-ray imaging device according to claim 2, characterized in that: The material of the phantom body (100) is hydroxyapatite.

4. The phantom for measuring bone density in an X-ray imaging device according to claim 2, characterized in that: The material of the phantom body (100) is dipotassium hydrogen phosphate.

5. The phantom for measuring bone density in an X-ray imaging device according to any one of claims 1 to 4, characterized in that: The maximum equivalent bone density value of the steps on the phantom body (100) is not less than 2.4 g / cm 2 .

6. An X-ray imaging device, characterized in that: The invention comprises an X-ray imaging device body and a phantom used for measuring bone density of an X-ray imaging device as claimed in any one of claims 1 to 5.

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