Tissue-mimicking phantom for omnidirectional slice thickness detection in ultrasonic tomography equipment

Abstract

The present invention discloses a tissue-mimicking phantom for omnidirectional slice thickness detection of ultrasonic tomography equipment. The tissue-mimicking phantom is in a truncated cone shape and comprises: a phantom shell, an acoustic window (3), a background tissue-mimicking material (9) and a target; the phantom shell is fixed by an upper panel (2), a lower panel (6) and a truncated cone target seat (8) therebetween; the phantom shell and the acoustic window (3) pasted on the side of the truncated cone together form a closed space, the closed space is filled with background tissue-mimicking material (9), the target is a diffuse scattering layer (7) closely attached to and covering the side of the truncated cone target seat (8); the upper panel (2) is provided with an inlet for filling the background tissue-mimicking material (9), and a sealing rubber is pasted on the upper panel. The tissue-mimicking phantom of the present invention can be used for omnidirectional slice thickness detection and evaluation of ultrasonic tomography equipment.

Description

Technical Field

[0001] The invention belongs to the field of medical device quality inspection, and in particular relates to a tissue-mimicking phantom used for omnidirectional slice thickness inspection of ultrasonic tomography equipment. Background Art

[0002] In clinical practice, doctors make diagnoses based on the information provided by ultrasound scanning sonograms, so image quality is considered the primary factor in measuring the quality of B-ultrasound products and judging whether they work properly and effectively. According to international consensus, technical indicators (i.e., performance) that characterize image quality include blind spots, detection depth, axial (longitudinal) resolution, lateral (transverse) resolution, pitch resolution, contrast resolution, and geometric errors of display and measurement. The only material and technical means that can objectively, quickly, realistically, and quantitatively evaluate the performance and quality of B-ultrasound equipment in all aspects of B-ultrasound equipment development, production, sales, use, maintenance, and legal management (quality supervision and inspection, metrology verification, and import and export commodity inspection) is the tissue-mimicking ultrasound phantom. "Ultrasonic tissue-mimicking phantom" is translated from English "Tissue Mimicking Ultrasound Phantom", which means a physical model of the human body that mimics soft tissue in terms of ultrasonic propagation characteristics. It is a passive test device composed of Ultrasonically Tissue-Mimicking Material (TM material) and a variety of test targets embedded in it, as well as acoustic windows, shells, indicative decorative panels, etc. Tissue-mimicking Ultrasound Phantom is a prescribed equipment for implementing national technical standards and metrological verification procedures, and has the characteristics of a standard instrument.

[0003] With the development of electronic technology and biomedical engineering, more and more diagnostic and treatment methods and equipment based on medical ultrasound have emerged. For example, ultrasound computed tomography (USCT) is a very promising technology for early breast tumor detection and diagnosis. This technology uses a ring array ultrasonic transducer to scan and image the breast in a water tank. Its imaging modes include B-ultrasound mode using ultrasonic reflection wave signal imaging, sound velocity measurement imaging mode using transmission wave signal, and acoustic attenuation mode. Ultrasonic scanning tomography can be achieved in many ways, such as forming a series of tomographic images through longitudinal mechanical scanning of a ring array, or forming tomographic images after mechanical scanning of multiple pairs of transducers for spatial sampling, or using a spatial semi-ellipsoidal array transducer for electronic scanning tomographic imaging. Ultrasonic tomography equipment usually uses degassed water as the coupling medium between the transducer and the human body. It is mainly used for three-dimensional ultrasonic scanning imaging of the breast, and can also be used for tomographic imaging of limbs and other parts.

[0004] According to the quality system requirements of medical device manufacturers and professional quality inspection institutions, all measuring instruments used for quality inspection must be regularly verified or calibrated. Tissue-mimicking ultrasound phantoms are "tissue substitutes" rather than measuring instruments. There is no standard instrument in the metrological sense, and it is impossible to implement metrological verification or calibration. However, since it directly affects the quality of ultrasound diagnostic equipment, the rules of regular inspection and comparison have been formed since the end of the last century, which are recognized and followed by all relevant parties. As a medical device, ultrasound tomography imaging equipment should use tissue-mimicking phantoms for imaging performance and quality inspection. At present, for new ultrasound imaging diagnostic equipment such as USCT, the current tissue-mimicking phantoms are no longer suitable for its performance testing. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical defects and provide a tissue-mimicking phantom for ultrasonic tomography imaging equipment detection, which can be specifically used to examine and detect the omnidirectional slice thickness of ultrasonic tomography imaging equipment and is an ultrasonic passive device.

[0006] To achieve the above object, the present invention provides a tissue-mimicking phantom for omnidirectional slice thickness detection of ultrasonic tomography equipment, wherein the tissue-mimicking phantom is in a truncated cone shape and comprises: a phantom shell, an acoustic window, a background tissue-mimicking material and a target; the phantom shell is fixed by an upper panel, a lower panel and a truncated cone target seat therebetween, the phantom shell and the acoustic window pasted on the side of the truncated cone together form a closed space, the closed space is filled with the background tissue-mimicking material, the target is a diffuse scattering layer closely attached to and covering the side of the truncated cone target seat; an inlet for filling the background tissue-mimicking material is opened on the upper panel, and a sealing rubber is pasted on the inlet.

[0007] As an improvement of the above device, the material of the phantom shell is hard structural plastic.

[0008] As an improvement of the above device, the acoustic window is made of a polyester film with a thickness of 50 μm-100 μm.

[0009] As an improvement of the above device, the acoustic window connects the upper panel and the lower panel, and the angle between the acoustic window section and the lower panel is in the range of 60° to 90°.

[0010] As an improvement of the above device, the background tissue-mimicking material is an aqueous polymer gel-based composite material.

[0011] As an improvement of the above device, the angle between the cut surface of the side of the truncated cone target seat and the lower panel ranges from 10° to 80°.

[0012] As an improvement of the above device, the diffuse scattering layer is formed by coating a layer of granular acoustic diffuse scattering material on a substrate, and the thickness of the layer is less than 1 mm.

[0013] As an improvement of the above device, the inlet of the upper panel is a circular hole arranged near the circumference and is blocked by a blocking rubber, and the blocking rubber is made of vacuum rubber.

[0014] As an improvement of the above device, the background tissue-mimicking material can be maintained using a special maintenance liquid, and the maintenance liquid is injected through the sealing rubber.

[0015] The advantages of the present invention are:

[0016] 1. Compared with existing similar products, the tissue-mimicking phantom designed and manufactured according to the present invention is specially used for omnidirectional slice thickness detection and pitch beam imaging performance evaluation of ultrasonic tomography equipment; a single measurement imaging can measure the slice thickness of all array elements imaging on the annular array transducer at 360°, and measure and quantify the difference of this parameter between the array elements, so as to obtain the circumferential uniformity of the annular array at the slice thickness parameter level;

[0017] 2. The present invention avoids artifacts caused by multiple reflections between the transducer and the acoustic window through the design of the inclined acoustic window;

[0018] 3. The tissue-mimicking body mold of the present invention has unique maintainability. Through regular maintenance and injection, the effective period of the body mold can be greatly extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a side external view of the tissue-mimicking phantom used for omnidirectional slice thickness detection of ultrasonic tomography equipment of the present invention;

[0020] Figure 2 It is a perspective view of the interior of the silent window of the tissue-mimicking phantom used for omnidirectional slice thickness detection of the ultrasonic tomography device of the present invention;

[0021] Figure 3 It is a side cross-sectional view of the tissue-mimicking phantom used for omnidirectional slice thickness detection of ultrasonic tomography equipment of the present invention;

[0022] Figure 4 It is a central cross-sectional view of the tissue-mimicking phantom used for omnidirectional slice thickness detection of ultrasonic tomography equipment of the present invention;

[0023] Figure 5 It is a schematic diagram of an embodiment of a tissue-mimicking phantom for omnidirectional slice thickness detection of an ultrasonic tomography device according to the present invention.

[0024] Reference numerals:

[0025] 1. Tissue-mimicking phantom 2. Upper panel 3. Acoustic window

[0026] 4. Sealing rubber 5. Round hole 6. Lower panel

[0027] 7. Diffuse scattering layer 8. Round cone target 9. Background tissue-mimicking material

[0028] 10. Ring array transducer DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0030] According to the quality system requirements of medical device manufacturers and professional quality inspection institutions, all measuring instruments used for quality inspection must be regularly verified or calibrated. Ultrasonic tissue phantoms are "tissue substitutes". Since they directly affect the quality of ultrasonic diagnostic equipment, regular inspection and comparison rules have been formed since the end of the last century, which are recognized and followed by all relevant parties. The corresponding products of the present invention are used for quality inspection and evaluation of ultrasonic tomography equipment, and for detection and measurement of circumferential slice thickness of ultrasonic imaging equipment.

[0031] The tissue-mimicking phantom of the present invention is an ultrasonic passive device specifically used for detecting the thickness of the acoustic beam slice and evaluating the imaging performance of ultrasonic tomography imaging equipment. Ultrasonic computed tomography (USCT) usually uses an annular array ultrasonic transducer to scan and image the human body (such as breast, etc.) in a water tank, and its imaging modes include B-ultrasound mode using ultrasonic reflection wave signal imaging, sound velocity measurement imaging mode using transmission wave signal, and acoustic attenuation mode. Ultrasonic scanning tomography can be achieved in many ways, such as forming a series of tomographic images through longitudinal mechanical scanning of an annular array, or forming tomographic images after mechanical scanning of multiple pairs of transducers for spatial sampling, or using a spatial semi-ellipsoidal array transducer for electronic scanning tomography. Ultrasonic tomography equipment usually uses degassed water as a coupling medium between the transducer and the human body, and is mainly used for three-dimensional ultrasonic scanning imaging of the breast, and can also be used for tomographic imaging of limbs and other parts.

[0032] like Figure 1 and Figure 2As shown, the tissue-mimicking phantom 1 is truncated cone-shaped and mainly consists of a phantom shell, an acoustic window 3, a target and a background tissue-mimicking material (TMM) 9. The phantom shell is fixed by an upper panel 2, a lower panel 6 and a truncated cone target seat 8, and the material of the phantom shell is a hard structural plastic; preferably, the hard structural plastic is organic glass (PMMA, chemical name is polymethyl methacrylate) material, and can also be other structural plastics, such as ABS acrylonitrile-butadiene-styrene terpolymer, polyvinyl chloride plastic, etc. The upper panel 2 and the lower panel 6 form the upper and lower surfaces of the truncated cone shape, and the truncated cone target seat 8 is arranged between the upper panel 2 and the lower panel 6. The phantom shell is formed by gluing the upper panel 2, the lower panel 6, and the truncated cone target seat 8 together to form a closed space with the acoustic window 3 on the side. The closed space is filled with background tissue-mimicking material (TMM) 9. The acoustic window 3 connects the upper panel 2 and the lower panel 6. The angle between the acoustic window 3 and the lower panel 6 is 60° to 90°. The angle is determined by the distance between the acoustic window 3 and the transducer surface and the longitudinal dimension of the transducer. This angle is to avoid multiple reflections between the acoustic window 3 and the transducer. The acoustic window 3 is made of a polyester film material with a thickness of 50μm-100μm, which is used to simulate the acoustic characteristics of human epidermal tissue.

[0033] like Figure 3 As shown, the target is a diffuse scattering layer 7, which is arranged on the side of the truncated cone target base 8, and its back is closely attached to the truncated cone target base 8. The diffuse scattering layer 7 has an inclination angle φ with the lower panel 6, and the inclination angle φ is usually a certain value in the range of 10° to 80°. The diffuse scattering layer 7 is less than 1mm thick and is composed of a layer of granular acoustic diffuse scattering material coated on a substrate. It has the function of diffuse scattering the incident sound wave.

[0034] like Figure 1 As shown, a circular hole 5 is provided on the upper panel 2 near the circular edge as a channel for filling the background tissue material 9. A sealing rubber 4 with excellent elasticity is attached to the outside of the circular hole 5. The material is vacuum rubber, which serves as an inlet for liquid injection and air extraction during maintenance of the tissue material.

[0035] Background tissue-mimicking material 9 is a material that mimics the acoustic parameters of human soft tissue. The material is an aqueous polymer gel-based composite material. The sound velocity of the ultrasonic tissue-mimicking material (TMM) is (1540±10) m / s, and the slope of the acoustic attenuation coefficient of the ultrasonic tissue-mimicking (TM) material is (0.7±0.05) dB / (cm·MHz). The parameters of the tissue-mimicking material are all values ​​measured under the condition of a temperature of [(23±3)℃].

[0036] Background The tissue-mimicking material 9 is the core part of the ultrasonic phantom. Variations in its composition, state, and acoustic properties will lead to functional failure. The tissue-mimicking material of the ultrasonic tissue-mimicking phantom is maintainable. The liquid contained in the tissue-mimicking material may evaporate through the gaps in the phantom shell. After the phantom has been used for a long time, the tissue-mimicking material may lose water and shrink. In the case of severe water loss, the phantom may fail completely and cannot be restored. The tissue-mimicking material can be maintained daily using a special aqueous maintenance liquid. The aqueous maintenance liquid can be injected through the sealing rubber 4 on the upper panel 2 using an injection needle; the aqueous maintenance liquid is specially formulated for the tissue-mimicking material. The daily maintenance cycle is related to the temperature and humidity environment of the phantom. The service life of the phantom can be greatly extended by daily maintenance by replenishing the maintenance liquid.

[0037] Figure 4 This is a schematic diagram of the use of the tissue-mimicking phantom for testing the imaging performance of ultrasonic tomography imaging equipment. The overall structure is in a closed or semi-closed water tank, and usually requires degassing. The device in the embodiment uses a ring array transducer 10, that is, the transducer is arranged in a partial or full arc shape. The tissue-mimicking phantom 1 is placed in water, and usually the lower panel 6 is placed on a horizontal platform immersed in water. It is usually necessary to use a water tank for ultrasonic coupling with a water surface higher than the upper panel of the phantom. Ensure that the center of the phantom is precisely aligned with the center of the ring array transducer 10, and take measures to remove bubbles attached to the acoustic window. Turn on the imaging device, set it to the transmit-receive state of all array elements, adjust the upper and lower positions of the ultrasonic probe, align the radiation surface with the acoustic window of the phantom, and obtain a two-dimensional image of the materials and structures in the phantom;

[0038] like Figure 5 As shown in the figure, when all the probe array elements participate in imaging, a circular bright band composed of scattered light spots can be seen on the instrument screen; when only some of the probe array elements participate in imaging, only part of the circular bright band in the direction corresponding to the position of the active array elements is shown on the instrument screen. Use the electronic cursor of the instrument under test to measure the size d of the center of the bright band along the depth direction of the phantom, and the slice thickness at the depth indicated by the sound beam is:

[0039] s=d / tanφ=d / φ

[0040] Move the probe up and down to aim the scanning acoustic beam at the target surface at 1 / 2, 1 / 3 and 2 / 3 of the detection depth (measured using a phantom that includes the detection depth item), measure the size d of the center of each bright band along the depth direction, and then use the above formula to calculate the respective slice thickness s values.

[0041] The width of the bright band at each circumferential arc angle of the circular bright band composed of scattered light points can be measured, so that the slice thickness values ​​of the annular array elements in various directions can be compared, and the circumferential uniformity of the slice thickness can be quantitatively calculated.

[0042] After the test, take the phantom out of the water and wipe off the water on the surface with a soft towel.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A tissue-mimicking phantom for omnidirectional slice thickness detection of ultrasonic tomography equipment, characterized in that: The tissue-mimicking phantom is in the shape of a truncated cone, and comprises: a phantom shell, an acoustic window (3), a background tissue-mimicking material (9) and a target; the phantom shell is fixed by an upper panel (2), a lower panel (6) and a truncated cone target seat (8) therebetween; the phantom shell and the acoustic window (3) attached to the side of the truncated cone together form a closed space, the closed space is filled with the background tissue-mimicking material (9), and the target is a diffuse scattering layer (7) closely attached to and covering the side of the truncated cone target seat (8); the upper panel (2) is provided with an inlet for filling the background tissue-mimicking material (9), and a sealing rubber is attached to the inlet; The material of the phantom shell is hard structural plastic; The background tissue-mimicking material (9) is an aqueous polymer gel-based composite material.

2. The tissue-mimicking phantom according to claim 1, characterized in that: The acoustic window (3) is made of a polyester film with a thickness of 50 μm-100 μm.

3. The tissue-mimicking phantom according to claim 2, characterized in that: The acoustic window (3) connects the upper panel (2) and the lower panel (6), and the angle between the section of the acoustic window (3) and the lower panel (6) is in the range of 60° to 90°.

4. The tissue-mimicking phantom according to claim 1, characterized in that: The value range of the included angle between the cut surface of the side of the truncated cone target seat (8) and the lower panel (6) is 10° to 80°.

5. The tissue-mimicking phantom according to claim 4, characterized in that: The diffuse scattering layer (7) is composed of a layer of granular acoustic diffuse scattering material coated on a layer of substrate, and its thickness is less than 1 mm.

6. The tissue-mimicking phantom according to claim 1, characterized in that: The inlet on the upper panel (2) is a circular hole (5) arranged near the circumference and is blocked by a blocking rubber (4). The blocking rubber (4) is made of vacuum rubber.

7. The tissue-mimicking phantom according to claim 6, characterized in that: The background tissue-mimicking material (9) can be maintained using a special maintenance liquid, which is injected through the sealing rubber (4).

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