CN113920244A - Method and auxiliary tool for reconstructing skeleton digital model based on scanned image - Google Patents
Method and auxiliary tool for reconstructing skeleton digital model based on scanned image Download PDFInfo
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Abstract
The invention discloses a method for reconstructing a skeletal digital model based on a scanned image and an auxiliary tool, wherein an inner layer component model is obtained by carrying out image scanning, image segmentation and model reconstruction on the auxiliary tool; importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed inner layer component model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process; correcting the volume of the reconstructed bone digital model by using the volume change rate of the reconstructed model; the volume increasing proportion of each scanning and model reconstruction can be accurately known, then accurate correction is carried out, and the 3D model reconstruction precision is effectively improved. Experiments prove that compared with the traditional bone digital model reconstruction method, the absolute average deviation value of the bone digital model reconstructed by the method provided by the invention and the actual structure is 0.2-0.5mm smaller than that of the traditional method.
Description
Technical Field
The invention relates to the technical field of medical instruments, in particular to a method and an auxiliary tool for reconstructing a bone digital model based on a scanned image.
Background
At present, the application of 3D printing in medical treatment is emerging. The common 3D printing technology is mainly applied to medical treatment: printing prostheses, implants, templates, guides, and the like. The 3D printing technology has its irreplaceable advantages in realizing individualized designs. To achieve individualized design goals, these techniques often do not depart from the use of CT, MR images of the patient to reconstruct a 3D digital model of the patient's anatomy (e.g., bone).
For example, a chinese patent application with publication number CN107320221A discloses a method for making a deformed knee joint skeleton model based on 3D printing, which mainly comprises the following steps: (1) carrying out continuous tomography CT scanning on a patient to obtain image data; (2) carrying out threshold value distinguishing and binarization processing in medical software Mimics to obtain single femoral and tibial mask data and construct a three-dimensional model; (3) performing polygon processing and accurate surface processing in reverse engineering software to obtain a NURBS surface model; (4) and printing the pathological skeleton model with the ratio of 1:1 by using an FDM molding 3D printing technology.
For another example, a chinese patent publication No. CN110223391A discloses a 3D printing method and apparatus for a three-dimensional model of a bone. The method comprises the following steps: acquiring target data, wherein the target data is related data acquired by performing CT scanning or MRI scanning on a bone lesion part of a patient; establishing a three-dimensional model of the skeleton according to the target data; and printing the three-dimensional model of the skeleton by using a 3D printer.
However, in the prior art, errors of a reconstructed 3D model and actual errors are still at a rough level compared with the international dimensional accuracy standard, and the reconstruction accuracy cannot meet the high-accuracy assembly requirement, so that the clinical application of the 3D printing technology is restricted. The inventor researches and discovers that the factors causing the errors are many, such as different brands of scanning equipment, partial volume effect of CT and MR scanning, size error of a scanning machine, selection of specific scanning parameters, individual difference, posture factors and the like. However, the final result often results in a reconstructed model with a larger volume than the actual structure, and the ratio of the volume increase is different according to different specific anatomical structures, for example, the hip bone is generally 5-15% larger in reconstructed volume, and the volume increase often causes a larger deviation between the reconstructed model and the actual structure.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a method for reconstructing a bone digital model based on a scanned image, which has small reconstruction model error and high reconstruction precision.
The invention also provides an auxiliary tool used in the method.
In order to achieve the purpose, the invention adopts the following technical scheme.
A method for reconstructing a digital model of a bone based on a scanned image, comprising the steps of: 1) manufacturing an auxiliary tool, wherein the auxiliary tool comprises an inner layer component and an outer layer component, and the inner layer component is embedded or completely embedded in the outer layer component; the inner layer component is consistent with a target anatomical structure in CT gray scale or magnetic resonance relaxation time, and the outer layer component is consistent with human tissues outside the target anatomical structure in CT gray scale or magnetic resonance relaxation time; 2) scanning the target anatomical structure and the auxiliary tool to obtain an image, and then performing image segmentation and model reconstruction on the target anatomical structure and the inner layer assembly by adopting the same technical route; 3) importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process; 4) importing the reconstructed target anatomical structure model into reverse engineering software or 3D printing support software, measuring the volume of the reconstructed model of the target anatomical structure, and dividing the volume of the reconstructed model of the target anatomical structure by the volume change rate of the reconstructed model to obtain the corrected volume of the target anatomical structure model; 5) in reverse engineering software or 3D printing support software, a reconstructed model of the target anatomical structure is subjected to inward surface bias by using a surface bias algorithm, and the reconstructed model is close to a correction volume of the target anatomical structure by adjusting the surface bias distance.
More preferably, a plurality of inner layer assemblies with different shapes are arranged on a single outer layer assembly, and each inner layer assembly is synchronously scanned when the auxiliary tool is scanned; the shape of the inner component is selected from spherical, cylindrical, tubular, free-form, and a shape that is completely consistent with the target anatomy; each of the inner layer assemblies corresponds to a target anatomical mean value in CT gray scale or magnetic resonance relaxation time.
More preferably, a plurality of inner layer assemblies with the same shape are arranged on a single outer layer assembly, and each inner layer assembly is synchronously scanned when the auxiliary tool is scanned; each inner layer component corresponds to the mean value of the target anatomy of different populations in terms of CT gray scale or magnetic resonance relaxation time.
More preferably, the auxiliary tools are set, and each auxiliary tool is provided with at least two outer components with different CT gray scales or different magnetic resonance relaxation times so as to correspond to different crowds.
More preferably, one of said inner members is provided on a single of said outer members, said inner member having a shape that substantially conforms to the shape of the target anatomy; the inner assembly corresponds to a mean value of the target anatomy at CT gray scale or magnetic resonance relaxation time, and the outer assembly corresponds to a mean value of human tissue outside the target anatomy at CT gray scale or magnetic resonance relaxation time.
More preferably, the auxiliary tool is directly processed into a finished product through 3D printing.
Or the auxiliary tool is used for manufacturing the inner layer assembly firstly and then is sealed in the outer layer assembly to manufacture a finished product; when the inner layer assembly is manufactured, a 3D printing, mold curing molding or CNC machining mode is adopted; when the outer layer assembly is sealed, one of the following two modes is adopted: a) placing the inner layer material into the uncoagulated outer layer material to be solidified to obtain a finished product, b) placing the inner layer component into the perforated or movably-installed outer layer material with the cavity to be installed and molded.
More preferably, in step 2), the image obtained by scanning the target anatomy and the auxiliary tool is obtained by: the scan is performed in two separate scans or with an auxiliary tool in tandem with the patient's target anatomy.
More preferably, when the target anatomy and/or human tissue is multilayered, the inner layer member and/or the outer layer member are correspondingly multilayered.
More preferably, the method for reconstructing the digital bone model based on the scanned image further comprises a volume change rate correction step of: the registration of the three-dimensional model is completed by the least square algorithm and the like between the reconstructed model of the inner layer component and the original model of the inner layer component or a 3D model registration tool is used in reverse engineering softwareFinishing the registration of the reconstructed model of the inner layer assembly and the original model; after registration, the reconstructed model of the inner layer assembly is biased towards the inner side through a surface bias algorithm or function, the volume of the reconstructed model is approximate to the volume of the original model by adjusting the surface bias distance, the absolute average deviation of the model and the original model at the moment is obtained through deviation analysis, and the absolute average deviation is set as k1(ii) a Further adjusting the surface offset distance to minimize the absolute average deviation between the processed reconstructed model and the original model, and setting the minimum value as k2(ii) a Comparison k1、k2Magnitude of value, if k1、k2If the difference value is not larger than the threshold value, selecting a correction ratio x obtained by dividing the reconstructed model volume by the processed reconstructed model volume2To correct the volume of the target anatomical model.
More preferably, it is determined whether or not the correction ratio x is selected2To correct the volume of the target anatomical model, further comprising the steps of: let the pixel size of the scanned image be L, if k1And k is2All are greater than 0.301 x L, then the ratio x is not corrected2To correct the volume of the target anatomical model, if k2Not more than 0.301 x L, the correction ratio x is selected2To correct the volume of the target anatomical model.
An aid for reconstructing a digital model of a bone based on a scan image, comprising: an inner layer component and an outer layer component, wherein the inner layer component is embedded or completely embedded in the outer layer component; the inner assembly is aligned with the target anatomy at CT gray scale or magnetic resonance relaxation time, and the outer assembly is aligned with body tissue outside the target anatomy at CT gray scale or magnetic resonance relaxation time.
When the method is applied, an inner layer assembly model is obtained by carrying out image scanning, image segmentation and model reconstruction on the auxiliary tool; importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed inner layer component model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process; and correcting the volume of the reconstructed bone digital model by using the volume change rate of the reconstructed model.
The invention has the beneficial effects that: due to individual differences, differences in digital reconstruction methods, such a final volume increase ratio is often unknown for a particular anatomical reconstruction at a particular scan parameter for a particular individual. The auxiliary tool and the reconstruction method adopted by the invention can accurately know the volume increase proportion of each scanning and model reconstruction, and then carry out accurate correction, thereby effectively improving the reconstruction precision of the 3D model.
Experiments prove that compared with the traditional bone digital model reconstruction method, the absolute average deviation value of the bone digital model reconstructed by the method provided by the invention and the actual structure is 0.2-0.5mm smaller than that of the traditional method.
Drawings
Fig. 1 is a schematic structural view of an I-type auxiliary tool.
Fig. 2 is a schematic structural view of a type II auxiliary tool.
Fig. 3 is a schematic structural view of a type III auxiliary tool.
Reference numerals indicate the same.
1: inner layer assembly, 2: an outer layer assembly.
Detailed Description
In the description of the present invention, it should be noted that, for the terms of orientation, such as "central", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., it indicates that the orientation and positional relationship shown in the drawings are based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated without limiting the specific scope of protection of the present invention.
Furthermore, if the terms "first" and "second" are used for descriptive purposes only, they are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. Thus, a definition of "a first" or "a second" feature may explicitly or implicitly include one or more of the feature, and in the description of the invention, "at least" means one or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly specified or limited, the terms "assembled", "connected", and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; or may be a mechanical connection; the two elements can be directly connected or connected through an intermediate medium, and the two elements can be communicated with each other. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.
In the present invention, unless otherwise specified and limited, "above" or "below" a first feature may include the first and second features being in direct contact, and may also include the first and second features not being in direct contact but being in contact with each other through another feature therebetween. Also, the first feature being "above," "below," and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply an elevation which indicates a level of the first feature being higher than an elevation of the second feature. The first feature being "above", "below" and "beneath" the second feature includes the first feature being directly below or obliquely below the second feature, or merely means that the first feature is at a lower level than the second feature.
The following describes the embodiments of the present invention with reference to the drawings of the specification, so that the technical solutions and the advantages thereof are more clear and clear. The embodiments described below are exemplary and are intended to be illustrative of the invention, but are not to be construed as limiting the invention.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
A method of reconstructing a digital model of a bone based on a scanned image, comprising the following steps.
1) Manufacturing an auxiliary tool, wherein the auxiliary tool comprises an inner layer component and an outer layer component, and the inner layer component is embedded or completely embedded in the outer layer component; the inner assembly is aligned with the target anatomy at CT gray scale or magnetic resonance relaxation time, and the outer assembly is aligned with body tissue outside the target anatomy at CT gray scale or magnetic resonance relaxation time.
2) And scanning the target anatomical structure and the auxiliary tool to obtain an image, and then carrying out image segmentation and model reconstruction on the target anatomical structure and the inner layer assembly by adopting the same technical route.
3) And importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process.
4) And importing the reconstructed target anatomical structure model into reverse engineering software or 3D printing support software, measuring the volume of the reconstructed model of the target anatomical structure, and dividing the volume of the reconstructed model of the target anatomical structure by the volume change rate of the reconstructed model to obtain the corrected volume of the target anatomical structure model.
5) In reverse engineering software or 3D printing support software, a reconstructed model of the target anatomical structure is subjected to inward surface bias by using a surface bias algorithm, and the reconstructed model is close to a correction volume of the target anatomical structure by adjusting the surface bias distance.
Wherein the auxiliary tool is a two-layer or multi-layer structure, and when the target anatomical structure and/or human tissue are multi-layer, the inner layer component and/or the outer layer component are correspondingly arranged into multiple layers. The following description will be given taking a two-layer structure as an example. In a two-layer structure, the inner layer assembly is embedded or completely embedded in the outer layer material.
As shown in FIG. 1, the outer member 2 is made of a material that substantially conforms to the anatomy outside the target anatomy at CT scan gray scale or MR scan relaxation time. The inner layer component 1 is a size standard component, the standard component enclosed in the inner layer component is a basic shape with different forms, and can be a ball, a cylinder, a tube, a free-form surface or a form completely consistent with a target anatomical structure, and the like, and the used material is basically consistent with the average value of the target anatomical structure in the gray scale of a CT scanning image or the relaxation time of an MR scanning image.
As shown in fig. 2, in some embodiments, the range of variation in image gray scale or relaxation time of the target anatomy within the population is segmented, with different image gray scale, relaxation time materials corresponding to the average of the different segments. Similarly, the variation range of the image gray scale or relaxation time of human tissues outside the target anatomical structure in the crowd is segmented, and different image gray scale and relaxation time materials correspond to the average values of different segments. When the auxiliary tools are manufactured, the auxiliary tools can be designed in a set, and each set of auxiliary tools is internally provided with at least two outer layer assemblies 2 with different CT gray scales or different magnetic resonance relaxation times so as to correspond to different crowds; each outer component 2 is provided with a plurality of inner components 1 with the same shape, and each inner component 1 corresponds to the average value of the target anatomical structures of different people on the CT gray scale or the magnetic resonance relaxation time.
Due to the difference in CT gray scale or magnetic resonance relaxation time of the inner assemblies 1, it is preferable to arrange the inner assemblies 1 in a stepwise manner on the same outer assembly 2 according to the difference in CT gray scale or magnetic resonance relaxation time.
As shown in fig. 3, in some embodiments, an inner member 1 conforming to the morphology of the target anatomy may also be enclosed or embedded in a single outer member 2.
In order to facilitate the better understanding of the bone model reconstruction method of the present invention for those skilled in the art, the digital hip model reconstruction based on GE16 row or 32 row CT in south China is described as an example. In the following description, type I represents the auxiliary tool shown in fig. 1, type II represents the auxiliary tool shown in fig. 2, and type III represents the auxiliary tool shown in fig. 3.
In hip scanned images based on GE16 or 32 CT in south China, the average CT gray level of soft tissue around a single individual bone is generally in the range of 40-70Hu, the average value is about 55Hu, the average gray level of the hip bone is 300Hu 560Hu, the average value is 405Hu, the I-type outer layer structure is made of materials such as CT gray level 55Hu high polymer resin materials, high polymer gel or latex and the like, and inorganic salts such as calcium sulfate and the like are properly added, and the inner layer material is made of materials such as gypsum, viscose gypsum and the like, or CT gray level 405Hu made of a mixture of inorganic salts and high polymer materials (polyvinyl alcohol, polyvinyl acetate emulsion and the like). Type II, the CT tone of the material can be adjusted by adjusting the ratio of the inorganic salt to the polymer material to obtain a plurality of outer layer and inner layer materials with a stepwise arrangement of CT tones, for example, 3 outer layer materials of 45Hu, 55Hu and 65Hu, and 3 inner layer materials of 300Hu, 350Hu, 400Hu, 450Hu, 500Hu and 550Hu6, and a set of tool is formed by preparing 18 spheres with the same diameter from 6 inner layer materials and sealing the spheres in the 3 inner layer materials. Type III, the material is the same as type I, except that the standard enclosed or embedded therein is a component conforming to the target form.
The auxiliary tool machining method comprises the following steps: a digital model of the inner assembly standard is first designed. The shape of the outer layer material is not limited. Then obtaining a finished product through one of two technical routes: 1) additive manufacturing (3D printing) of multiple materials directly processes the finished product. 2) Firstly, manufacturing a high-precision inner-layer assembly, sealing the assembly in an outer-layer material to manufacture a finished product: the inner layer assembly may use: a) additive manufacturing (3D printing), b) manufacturing a mould, introducing an inner layer material into the mould, curing and molding, and c) carrying out cutting and milling on a condensed and molded block by CNC (computer numerical control) machining. The enclosing outer layer material can adopt the following steps according to different outer layer materials: a) placing the inner layer material into the uncoagulated outer layer material, obtaining a finished product after the outer layer material is solidified, b) placing the inner layer component into the outer layer material component with the cavity which is punched or movably installed, and installing and forming.
The using method comprises the following steps: the volume of the model I and the volume of the model II are small, the model I and the model II are scanned together with a target anatomical structure of a patient to obtain an image containing the target anatomical structure and a tool of the model I or the model II, the image segmentation and the model reconstruction are carried out on the inner layer components of the target anatomical structure and the tool of the model I or the tool of the model II by adopting the same technical route, a component with a topological shape similar to the topological structure is selected from the inner layer components of the reconstructed tool I, a component with an inner layer material similar to the target anatomical structure and the gray level of surrounding tissues is selected from the tool of the model II, the selected inner layer component model is introduced into reverse engineering software or 3D printing support software to calculate the volume of the reconstructed model, and the ratio (volume change rate) of the volume of the reconstructed model caused by the whole technical process is obtained by dividing the volume of the original component. The corrected volume of the target anatomy can be calculated by measuring the volume of the reconstructed model of the anatomy in software divided by this ratio. And performing inward surface bias on the reconstructed model of the target anatomical structure by using a surface bias algorithm or in software, and enabling the processed model to be close to the correction volume of the target anatomical structure by adjusting the surface bias distance, wherein the corrected model eliminates model amplification and is closer to a real anatomical structure.
The III-type tool needs to be scanned independently before and after the scan of the anatomical structure (the scan parameter is the same as the scan parameter of the anatomical structure), the same technical route is adopted to carry out image segmentation and model reconstruction on the target anatomical structure and the inner layer component of the IIII-type tool, the inner layer component model is led into reverse engineering software or 3D printing support software to calculate the reconstructed model volume, and the ratio (volume change rate) of the reconstructed model volume caused by the whole technical process is obtained by dividing the reconstructed model volume by the original component volume. The corrected volume of the target anatomy can be calculated by measuring the volume of the reconstructed model of the anatomy in software divided by this ratio. And performing inward surface bias on the reconstructed model of the target anatomical structure by using a surface bias algorithm or in software, and enabling the processed model to be close to the correction volume of the target anatomical structure by adjusting the surface bias distance, wherein the corrected model eliminates model amplification and is closer to a real anatomical structure.
And (6) verifying.
Optionally, a verification method is used in the above process for the ratio (assuming that the ratio is x) participating in the subsequent calculation1) Carrying out proper correction, completing registration of the three-dimensional model by the inner layer component reconstructed digital model of the selected I-type or II-type tool and the digital model of the original standard component by using a least square algorithm or completing registration of the reconstructed inner layer component and the original digital model by using a 3D model registration tool in reverse engineering software (such as geoimagic and the like), knowing the average deviation of the reconstructed model and the original digital model by using a software three-dimensional deviation analysis function (or calculating the average Hausdorff distance by using an equivalent surface extraction algorithm and the like as the absolute average deviation) after registration, and biasing the reconstructed model inwards by using a surface biasing algorithm or functionThe volume of the reconstructed model of the component is made to approximate the volume of the original component by adjusting the surface offset distance, and the absolute average deviation (set as k) between the processed model and the original model is known by deviation analysis1) (ii) a Further adjusting the surface offset distance to minimize the absolute average deviation between the processed reconstructed module model and the original module (assuming the minimum value is k)2) (ii) a If k is1、k2If the difference is large, whether the reconstruction technology flow is influenced by noise or not needs to be checked, and whether the reconstruction technology route reconstruction model needs to be changed or not needs to be checked; if k is1、k2The ratio of the reconstructed component model volume divided by the processed reconstructed component model volume (assuming this ratio is x) is chosen to be as desired2Correction ratio) to further correct the volume of the target anatomy.
And (5) verifying the standard.
It may also be determined during the verification whether the correction ratio should be selected to participate in calculating the corrected volume of the anatomical structure by the following method. Let the pixel size of the scanned image be L, first know k1And k is2Whether it is close to or less than 0.301 x L, i.e. if k is1And k is2All are obviously greater than 0.301 × L, which indicates that the technical process of the model reconstruction method needs to be improved. If k is2X is selected to be close to or less than 0.301 x L2And entering subsequent correction calculation. The principle is as follows: the method can be used for mathematically proving that the average deviation of all reconstruction models approaches to 0.301L after a slice-level reconstruction method is adopted to reconstruct an irregular anatomical structure for infinite times in an ideal state, the reconstruction error of a certain reconstruction method can be judged to reach a more ideal level by taking the average deviation as a standard, and if the corrected reconstruction error is still obviously greater than 0.301L, the problem exists in the model reconstruction technical process. .
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
It will be appreciated by those skilled in the art from the foregoing description of construction and principles that the invention is not limited to the specific embodiments described above, and that modifications and substitutions based on the teachings of the art may be made without departing from the scope of the invention as defined by the appended claims and their equivalents. The details not described in the detailed description are prior art or common general knowledge.
Claims (10)
1. A method for reconstructing a digital model of a bone based on a scanned image, comprising the steps of:
1) manufacturing an auxiliary tool, wherein the auxiliary tool comprises an inner layer component and an outer layer component, and the inner layer component is completely embedded or embedded in the outer layer component; the inner layer component is consistent with a target anatomical structure in CT gray scale or magnetic resonance relaxation time, and the outer layer component is consistent with human tissues outside the target anatomical structure in CT gray scale or magnetic resonance relaxation time;
2) scanning the target anatomical structure and the auxiliary tool to obtain an image, and then performing image segmentation and model reconstruction on the target anatomical structure and the inner layer assembly by adopting the same technical route;
3) importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process;
4) importing the reconstructed target anatomical structure model into reverse engineering software or 3D printing support software, measuring the volume of the reconstructed model of the target anatomical structure, and dividing the volume of the reconstructed model of the target anatomical structure by the volume change rate of the reconstructed model to obtain the corrected volume of the target anatomical structure model;
5) in reverse engineering software or 3D printing support software, a reconstructed model of the target anatomical structure is subjected to inward surface bias by using a surface bias algorithm, and the reconstructed model is close to a correction volume of the target anatomical structure by adjusting the surface bias distance.
2. The method of claim 1, wherein a plurality of inner layer components with different shapes are arranged on a single outer layer component, and the inner layer components are scanned synchronously when the auxiliary tool is scanned; the shape of the inner component is selected from spherical, cylindrical, tubular, free-form, and a shape that is completely consistent with the target anatomy; each of the inner layer assemblies corresponds to a target anatomical mean value in CT gray scale or magnetic resonance relaxation time.
3. The method for reconstructing a digital model of a bone according to claim 1, wherein a plurality of inner assemblies having the same shape are disposed on a single outer assembly, and the inner assemblies are scanned simultaneously when the auxiliary tool is scanned; each inner layer component corresponds to the mean value of the target anatomy of different populations in terms of CT gray scale or magnetic resonance relaxation time.
4. A method for reconstructing a digital model of a bone based on a scanned image as claimed in claim 2 or 3, wherein said auxiliary tools are provided in sets, each set having at least two outer components with different CT gray levels or different mr relaxation times for different groups of people.
5. The method of claim 1, wherein one of said inner members is disposed on a single of said outer members, said inner member having a shape substantially conforming to a shape of the target anatomy; the inner assembly corresponds to a mean value of the target anatomy at CT gray scale or magnetic resonance relaxation time, and the outer assembly corresponds to a mean value of human tissue outside the target anatomy at CT gray scale or magnetic resonance relaxation time.
6. The method for reconstructing a digital bone model based on scanned images as claimed in claim 1, wherein said auxiliary tool is directly processed into a finished product by 3D printing;
or the auxiliary tool is used for manufacturing the inner layer assembly firstly and then is sealed in the outer layer assembly to manufacture a finished product; when the inner layer assembly is manufactured, a 3D printing, mold curing molding or CNC machining mode is adopted; when the outer layer assembly is sealed, one of the following two modes is adopted: a) placing the inner layer material into the uncoagulated outer layer material to be solidified to obtain a finished product, b) placing the inner layer component into the perforated or movably-installed outer layer material with the cavity to be installed and molded.
7. The method of claim 1, wherein in step 2), the scanning of the target anatomy and the auxiliary tool is performed in two separate scans or the auxiliary tool is scanned together with the target anatomy of the patient.
8. The method for reconstructing a digital model of a bone according to claim 1, wherein when the target anatomy and/or human tissue is multi-layered, said inner layer component and/or said outer layer component are correspondingly arranged in multiple layers.
9. The method of claim 1, further comprising a volume change rate correction step of:
the registration of the three-dimensional model is completed by the reconstructed model of the inner layer component and the original model of the inner layer component by using a least square algorithm or the registration of the reconstructed model of the inner layer component and the original model is completed by using a 3D model registration tool in reverse engineering software;
after registration, by a face bias algorithm or functionThe reconstructed model of the layer assembly is biased towards the inner surface, the volume of the reconstructed model is approximate to the volume of the original model by adjusting the surface bias distance, the absolute average deviation of the model and the original model at the moment is obtained by deviation analysis and is set as k1；
Further adjusting the surface offset distance to minimize the absolute average deviation between the processed reconstructed model and the original model, and setting the minimum value as k2；
Comparison k1、k2Magnitude of value, if k1、k2If the difference value is not larger than the threshold value, selecting a correction ratio x obtained by dividing the reconstructed model volume by the processed reconstructed model volume2To correct the volume of the target anatomical model;
judging whether to select the correction ratio x2To correct the volume of the target anatomical model, further comprising the steps of: let the pixel size of the scanned image be L, if k1And k is2All are greater than 0.301 x L, then the ratio x is not corrected2To correct the volume of the target anatomical model, if k2Not more than 0.301 x L, the correction ratio x is selected2To correct the volume of the target anatomical model.
10. An aid for reconstructing a digital model of a bone based on a scan image, comprising: an inner layer component and an outer layer component, wherein the inner layer component is embedded or completely embedded in the outer layer component; the inner layer component is consistent with a target anatomical structure in CT gray scale or magnetic resonance relaxation time, and the outer layer component is consistent with human tissues outside the target anatomical structure in CT gray scale or magnetic resonance relaxation time;
when the method is applied, an inner layer assembly model is obtained by carrying out image scanning, image segmentation and model reconstruction on the auxiliary tool; importing the reconstructed inner layer component model into reverse engineering software or 3D printing support software, calculating the volume of the reconstructed inner layer component model, and dividing the volume of the reconstructed inner layer component model by the volume of the original inner layer component to obtain the volume change rate of the reconstructed model caused by the whole technical process; and correcting the volume of the reconstructed bone digital model by using the volume change rate of the reconstructed model.
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| CN114559654B (en) * | 2022-02-28 | 2023-11-28 | 深圳市创想三维科技股份有限公司 | 3D model punching method and device, terminal equipment and readable storage medium |
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