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3d printing materials and their use in medical education: a review of current technology and trends for the future

by:Tuowei     2019-08-13
3d printing is a new and developing technology.
It is rapidly expanding and is now being used for health education. Patient-
Specific models with anatomical Fidelity created from imaging datasets have the potential to significantly improve the knowledge and skills of a new generation of surgeons.
This review provides an overview of the five technical steps required to complete the printing model: including (1)
Select the anatomical area of interest ,(2)
Creation of 3D geometry ,(3)
Optimization and appropriate selection of printed files (4)
3D printer and (5)materials.
All these steps take time, expertise and money.
Therefore, in order to optimize the value of education, it is essential to have a thorough understanding of the needs of education.
At present, most of the printed materials available are rigid, so their flexibility and elasticity are not optimal, unlike biological tissues.
We believe that the simulation and adjustment of material properties through the manufacture of composite materials and/or mixed materials will ultimately allow patients-
Specific models with anatomical and tissue fidelity.
Foreword the rapid development of 3D printing technology has created new learning and teaching tools for medical education.
Ability to produce patients
Specific electronic models in medical digital imaging and communication (DICOM)
The data obtained during CT, MRI or ultrasound scanning is combined with new, cheaper 3D printing techniques.
Depending on the area of interest, these printed models show anatomical and structural fidelity consistent with the patient\'s actual disease process.
1 2 this Fidelity allows learners to view and understand general pathology and structural relationships prior to surgical intervention.
In turn, better understanding and visualization enable the surgical team to plan interventions more accurately and guide the removal of edges, simulate the appropriate implant size, and sometimes create the implant itself using 3D printing techniques.
However, the vast majority of printing models are made of hard materials, and only a few have a certain flexibility and elasticity.
Although hard materials are sufficient to reconstruct anatomical fidelity, reconstruction of models with tissue features similar to human pathological specimens has always been a challenge. Patient-
Specific pre-intervention practices can be improved with more representative materials.
This is only possible after a firm understanding of the tissue features required for the model and the ability of the printer to mix composites to simulate human tissue.
The type of printed material that can be printed depends on the type of printer used.
As many groups are using 3D printing technology, more people are looking to move into this expanding area, and we believe that a review of the 3D printing process will be an important starting point for medical educators.
As with every educational tool, the proper construction and use of these models is guided by educational goals.
Once the requirements are identified, there are basically five important and often relevant steps in the 3D printing process to create a patient
Specific models with anatomical and/or tissue Fidelity :(1)
Capture areas of interest ,(2)
Create 3D geometry from a data set specific to the area of interest ,(3)
Convert a 3D object to a file ready to print ,(4)
Choose the right 3D printer and (5)
Choose the right material to use (figure 1).
The main focus of the review is to describe the process required to create a 3D patient
Specific models and examples, we highlight the step-by-step 3D printing process by referring throughout the review process to the creation of a thoracic aorta with a root aneurysm.
We also discuss the available 3D printing materials that are best suited to various organizational types.
Finally, we propose future directions and research areas to advance the field of printed materials.
Download figureOpen in the new tabDownload powerpoint figure 1 the steps required to create a 3D print model in healthcare education.
Capturing areas of interest understanding the needs the first step in creating a new tool for medical education using 3D printing includes defining educational goals.
Is it necessary to teach anatomy, pre-procedure planning or technical skills?
Also, what is the anatomical area of interest and how much needs to be included?
Understanding the educational needs or learning gaps you are trying to address is critical to creating the most appropriate education and costsEffective mode.
When planning a 3D printing model, four basic features of the model should be addressed and aligned with educational needs: Size: How many organs or anatomical areas are required?
For example, if the purpose is to teach the anatomy of the root of the aorta, is the whole ascending aorta required to guide the learner?
Surrounding structure: is it necessary for the surrounding structure to describe the relationship of the particular anatomical region that you are interested in?
For tumors and invasive cancers, having multiple different structures is essential to understand the relationship and plan with resection.
Surgery: Do you want learners to see not only the pathological anatomy, but also the anatomy or resection?
In this case, more emphasis will be placed on the precise anatomical details including the surrounding structure, especially in the case of the treatment of potential tumor resection.
If you need a model that allows cutting, cutting and stitching, the material properties of the model will be essential.
Accuracy and resolution of the model: how much fine detail and resolution do you need for your teaching?
Some models have a print resolution of 1mm, is this necessary?
These four considerations will have an impact on the type of imaging used to capture the area of interest, the resolution required, the nature of the materials and composites used, and the type of 3D printer to be used.
All of this will have a direct impact on the final cost of the 3D printing model.
With regard to the thoracic aorta, we would like to create a 3D printed and anatomical correct model with a root aneurysm that is able to teach the geometry of the thoracic aorta to residents in cardiac surgery.
We limit the representation of the aorta to the beginning of the root, ascending aorta, arch, and descending aorta (figure 2).
It also includes three branches (
From the near side to the far side: head arm artery, left common neck artery, left subclavian artery)
The beginning of two forensic doctors.
We kept the true size of the artery, but ignored the patient\'s calcium stove.
To ensure the representation of important details in the final product, the model requires high accuracy and resolution.
Download figureOpen in figure 2 of the new tabDownload powerpoint for teaching purposes, showing the geometry of the thoracic aortic model.
Once the requirements have been identified, discussions on these requirements should be shared with radiologists whose expertise is to select enough medical imaging processes for your specific 3D printing simulator, and the accuracy of the imaging data appropriately represented.
The concept of a medical imaging process can be seen as a large number of 2D images taken one by one, separated from the previously determined controlled thickness;
Therefore, 3D representation is achieved by simply stacking the continuous layers of 2D images into 3D volumes.
This explains why the accuracy of 3D geometry decreases as the thickness between each slice increases (see figure 3).
Low resolution creates a lot of space between 2D images, losing potentially important anatomical details.
It is generally recommended that the distance between the two pieces be 1mm or less than 4mm, but Matsumoto et al found 1.
5-3mm is the appropriate thickness of the chest and abdomen, 0. 4–0.
The bones and joints are 75mm.
In our lab, we used the slice thickness of 0.
625mm in our reproductive cardiovascular (
Thoracic aorta with root aneurysm)
Anatomy of the liver.
Download the new tabDownload powerpointFigure month (A)
Illustration of a flat 2D image of an area of interest captured by most medical imaging techniques ,(B)
Segmentation of object crossingsection (black circles)
Extraction, and (C)
The interpolation required to fill the missing volume between segments.
Some imaging processes are used in radiology to capture 2D images of the human body, but the most common techniques are still CT and MRI.
For these two methods, the contrast agent was injected into the patient before each acquisition, and the tissue was better organized by enhancing the contrast of the interested structure.
Controlling the noise and resolution of the image also affects the quality of the 2D image.
It is always recommended to use very high resolution data imaging;
However, depending on the needs and functionality of the 3D printer selected for manufacturing, high resolution may not be required.
As will be reviewed later, only a few printing techniques and equipment models can reproduce very fine details.
If you are interested in printing the structure of the chest and vascular system of the heart, the best way to visualize the arteries and veins is CT angiography and MRI angiography.
CT is the method we selected to capture the geometry of the thoracic aortic model.
ECG is required for both CT and MRI
For example, gated acquisition to identify the geometry of contraction and/or expansion, while reducing body movement 7, is critical to avoiding blurry images and thus improving the visibility of the aortic valve
In the literature, CT data sets were also used for other aortic models s8 and geometry, such as the heart with congenital diseases, 9 aneurism in the abdominal trunk, 10 trachea trees 11, and esophagus.
Similarly, the structures of pulmonary valves, 13 cardiac tumors 14, and thoracic aorta 15 were replicated from MRI images.
Data sets from multiple imaging sources can be merged to get the best results.
In fact, a mixture of traditional CT and CT angiography images has created the pulmonary artery for training in chest surgery.
16 similarly, cardiac surgery and interventional cardiology models were developed with CT and MRI17 and mitral valve models through CT and esophageal ultrasound.
18 models that replicate soft tissue and bones, such as the Assembly of the lungs and chest, are made from CT image 19 and need to be optimized for imaging of multiple tissue densities.
Friedman et al used CT and standard algorithms to capture bone geometry, minimizing artifacts in contact between bones and soft tissue, while using MRI to provide high contrast between cortical bone and surrounding tissue.
Has been taken from CT20-22 or microCT, 23, and Cone beam CT (
Cone formed by X-rays)
Multi-layer CT (
The number of pieces is large, so the resolution is better)
It is known that other suitable methods are available in cranial facial surgery.
24. in the field of neurosurgery, CT and MRI have been used to replicate blood vessels and large brain tissue.
25 26 CT imaging data have been used in Otolaryngology
Head and Neck Surgery training for the creation of rhinoplasty, subnasal sinus, skull base and chin Phantom, 27 deformed skulls, 28 as well as cortical brain tumor structures formed through the skin, bones, the spine membrane is surrounded by normal brain.
29 however, a single CT dataset can also provide sufficient information to perform geometric extraction from a 2D image, just as with a phantom of complex neck anatomy 30 and the repair of intra-vascular aneurysm of a cerebral artery.
31 Finally, when metal elements participate in CT imaging (
Such as: prosthesis, steel plate, screw, etc)
Artifacts that distort the geometry of the structure due to beam hardening or scattering can be well controlled by dual energy CT, thus providing a second less powerful X-
For better image quality, after the traditional light.
Understanding the requirements the first step in creating new tools for medical education using 3D printing includes defining educational goals.
Is it necessary to teach anatomy, pre-procedure planning or technical skills?
Also, what is the anatomical area of interest and how much needs to be included?
Understanding the educational needs or learning gaps you are trying to address is critical to creating the most appropriate education and costsEffective mode.
When planning a 3D printing model, four basic features of the model should be addressed and aligned with educational needs: Size: How many organs or anatomical areas are required?
For example, if the purpose is to teach the anatomy of the root of the aorta, is the whole ascending aorta required to guide the learner?
Surrounding structure: is it necessary for the surrounding structure to describe the relationship of the particular anatomical region that you are interested in?
For tumors and invasive cancers, having multiple different structures is essential to understand the relationship and plan with resection.
Surgery: Do you want learners to see not only the pathological anatomy, but also the anatomy or resection?
In this case, more emphasis will be placed on the precise anatomical details including the surrounding structure, especially in the case of the treatment of potential tumor resection.
If you need a model that allows cutting, cutting and stitching, the material properties of the model will be essential.
Accuracy and resolution of the model: how much fine detail and resolution do you need for your teaching?
Some models have a print resolution of 1mm, is this necessary?
These four considerations will have an impact on the type of imaging used to capture the area of interest, the resolution required, the nature of the materials and composites used, and the type of 3D printer to be used.
All of this will have a direct impact on the final cost of the 3D printing model.
With regard to the thoracic aorta, we would like to create a 3D printed and anatomical correct model with a root aneurysm that is able to teach the geometry of the thoracic aorta to residents in cardiac surgery.
We limit the representation of the aorta to the beginning of the root, ascending aorta, arch, and descending aorta (figure 2).
It also includes three branches (
From the near side to the far side: head arm artery, left common neck artery, left subclavian artery)
The beginning of two forensic doctors.
We kept the true size of the artery, but ignored the patient\'s calcium stove.
To ensure the representation of important details in the final product, the model requires high accuracy and resolution.
Download figureOpen in figure 2 of the new tabDownload powerpoint for teaching purposes, showing the geometry of the thoracic aortic model.
Once the requirements have been identified, discussions on these requirements should be shared with radiologists whose expertise is to select enough medical imaging processes for your specific 3D printing simulator, and the accuracy of the imaging data appropriately represented.
The concept of a medical imaging process can be seen as a large number of 2D images taken one by one, separated from the previously determined controlled thickness;
Therefore, 3D representation is achieved by simply stacking the continuous layers of 2D images into 3D volumes.
This explains why the accuracy of 3D geometry decreases as the thickness between each slice increases (see figure 3).
Low resolution creates a lot of space between 2D images, losing potentially important anatomical details.
It is generally recommended that the distance between the two pieces be 1mm or less than 4mm, but Matsumoto et al found 1.
5-3mm is the appropriate thickness of the chest and abdomen, 0. 4–0.
The bones and joints are 75mm.
In our lab, we used the slice thickness of 0.
625mm in our reproductive cardiovascular (
Thoracic aorta with root aneurysm)
Anatomy of the liver.
Download the new tabDownload powerpointFigure month (A)
Illustration of a flat 2D image of an area of interest captured by most medical imaging techniques ,(B)
Segmentation of object crossingsection (black circles)
Extraction, and (C)
The interpolation required to fill the missing volume between segments.
Some imaging processes are used in radiology to capture 2D images of the human body, but the most common techniques are still CT and MRI.
For these two methods, the contrast agent was injected into the patient before each acquisition, and the tissue was better organized by enhancing the contrast of the interested structure.
Controlling the noise and resolution of the image also affects the quality of the 2D image.
It is always recommended to use very high resolution data imaging;
However, depending on the needs and functionality of the 3D printer selected for manufacturing, high resolution may not be required.
As will be reviewed later, only a few printing techniques and equipment models can reproduce very fine details.
If you are interested in printing the structure of the chest and vascular system of the heart, the best way to visualize the arteries and veins is CT angiography and MRI angiography.
CT is the method we selected to capture the geometry of the thoracic aortic model.
ECG is required for both CT and MRI
For example, gated acquisition to identify the geometry of contraction and/or expansion, while reducing body movement 7, is critical to avoiding blurry images and thus improving the visibility of the aortic valve
In the literature, CT data sets were also used for other aortic models s8 and geometry, such as the heart with congenital diseases, 9 aneurism in the abdominal trunk, 10 trachea trees 11, and esophagus.
Similarly, the structures of pulmonary valves, 13 cardiac tumors 14, and thoracic aorta 15 were replicated from MRI images.
Data sets from multiple imaging sources can be merged to get the best results.
In fact, a mixture of traditional CT and CT angiography images has created the pulmonary artery for training in chest surgery.
16 similarly, cardiac surgery and interventional cardiology models were developed with CT and MRI17 and mitral valve models through CT and esophageal ultrasound.
18 models that replicate soft tissue and bones, such as the Assembly of the lungs and chest, are made from CT image 19 and need to be optimized for imaging of multiple tissue densities.
Friedman et al used CT and standard algorithms to capture bone geometry, minimizing artifacts in contact between bones and soft tissue, while using MRI to provide high contrast between cortical bone and surrounding tissue.
Has been taken from CT20-22 or microCT, 23, and Cone beam CT (
Cone formed by X-rays)
Multi-layer CT (
The number of pieces is large, so the resolution is better)
It is known that other suitable methods are available in cranial facial surgery.
24. in the field of neurosurgery, CT and MRI have been used to replicate blood vessels and large brain tissue.
25 26 CT imaging data have been used in Otolaryngology
Head and Neck Surgery training for the creation of rhinoplasty, subnasal sinus, skull base and chin Phantom, 27 deformed skulls, 28 as well as cortical brain tumor structures formed through the skin, bones, the spine membrane is surrounded by normal brain.
29 however, a single CT dataset can also provide sufficient information to perform geometric extraction from a 2D image, just as with a phantom of complex neck anatomy 30 and the repair of intra-vascular aneurysm of a cerebral artery.
31 Finally, when metal elements participate in CT imaging (
Such as: prosthesis, steel plate, screw, etc)
Artifacts that distort the geometry of the structure due to beam hardening or scattering can be well controlled by dual energy CT, thus providing a second less powerful X-
For better image quality, after the traditional light.
4 Creating 3D geometry from a data set specific to the region of interest once sufficient clinical imaging data set is obtained, an electronic geometry object needs to be created.
In general, a 3D object means a component that will be made of a particular material.
For example, if the component is made up of two different objects, such as bones and ligaments, the two geometries need to be defined separately before printing, and then they are reconnected together, proper manufacturing as a component (see figure 4).
Usually, for the sake of clarity, the two objects are made or printed in different colors from different materials.
Download figureOpen in the new tabDownload powerpoint figure 4, and two different objects are made of different materials or printed in different colors to create a component.
The thoracic aortic model with root aneurysm does not include any secondary factors, such as the calcium focus of the aortic wall.
Therefore, a 3D printing material is needed to reconstruct the arterial wall evenly.
When different objects are involved, it is better to define the points directly from the obtained jpeg image by extracting the points along the profile of the anatomical structure and defining its geometry.
This extraction process is called segmentation and is often based on thresholds, so color contrast between tissue density is used to separate the tissue structure into different objects.
Some may prefer to define geometry by dividing larger structures;
However, this may be a complex
Experienced design software users.
When defining an object from an image, the contrast or threshold of the split is highly dependent on the image.
Threshold levels often vary depending on the patient image, and the image quality from one slice to another may need to change the threshold level.
Therefore, verification of the correct identification of the anatomical structures of interest from the imaging data needs to be checked.
Once the threshold level is defined, the divided points can be extracted along the data set, however, for each manufacturing, no point can be accurately copied, resulting in changes or features between models.
Figure 12 rapid prototyping method with red arrows indicating the direction of movement (x, y, z axes).
As shown in Figure 13, the supporting material cannot be deposited in a blank space, so models with prominence usually need to be filled or supported in the lattice (or scaffold)forms.
In addition, the filling material is designed to strengthen the structure during the printing process, thus avoiding the deformation of the model when the material is cured.
Download figureOpen in the new tabDownload powerpoint figure 13 structure, the highlighted part of the structure is filled with a lattice structure, supporting material, or non-cured material. With silk (FDM)or liquids (SLA)
The supporting material provides a grid that can be easily disassembled by hand with the tool;
However, in order to get a good finish, they usually leave unwanted impressions on surfaces that require additional polishing.
This step of the process is very subtle because it is possible to damage the model by losing the details of the geometry.
When the model is completed by dissolution, some supporting materials can also be easily removed, just like water-soluble pvc.
In PJ, the volume of the solidified wax support material used to fill the highlights.
For models that are easily soluble, engraving tools are usually used to clean models and water spray devices.
Otherwise, the solution bath can remove the filling required for printing on its own.
If your 3D printer makes a model using powder (BJ, SLS)
, The prominent part will be filled with uncured materials as support.
It\'s also easy to clean up.
It is important to note that models printed with undissolved grids or wax supporting materials can be very complicated to clean up, especially when it is not easy to approach the cavity with hands or tools.
Cost of printing: Easiest, easiest to get and cost for 3D printers, materials and technical support-
37, also the cheapest technology, see Table 1.
Prices usually go up from BJ to SLA, and finally SLS and PJ.
View this table: View the main features of the inline View pop-up table 1 Rapid prototyping method: Stereo Vision (SLA), polyJet (PJ)
Model of molten deposition (FDM)
Selective Laser Sintering (SLS)
Injection of adhesive (BJ)
With regard to material costs, FDM filaments once again become the cheapest material of all 3D printer types and should be considered in large print volumes where material performance and high print resolution are not the main concerns.
Also, they are easy to store and use, which leads to the majority of users
Friendly process.
The SLA and PJ can provide high resolution, but they are also much more expensive.
SLA is the highest resolution in all types of 3D printers, while PJ printers allow the use and mixing of multiple materials in one print.
BJ is also very cost-effective.
Effective, low overall cost of printing.
These powders are a little more expensive than the filaments of FDM, and nevertheless, their advantage is that they can be reused when they are not cured, but are used as support for previous printing.
Therefore, there is little waste of material compared to liquid and silk methods.
In addition, the BJ printer is fast and easy to use and maintain.
The main consumables components are cheap and easy to replace.
However, the BJ model is more vulnerable than FDM printing without processing.
In terms of technical requirements, the risk of a printer malfunction in a limited company is rare and easy to solve.
Common problems can be summarized as the melting or sliding problem of the blockage caused by the material through the nozzle, or when the part is not properly attached to the underheated print bed.
In a finite difference printer, most of the faults are caused by the design of the 3D model, not any problem with the machine itself.
The technology that requires the broadest range of technical support is PJ.
In order to avoid the blockage of the liquid from potential solidification in the nozzle, the technician should use all the loaded materials for weekly maintenance (
If there is no scheduled print)
Provides continuous material flow in the printer.
In addition, using very specific technology, multiple parts of the machine need to be cleaned frequently, and errors can easily damage the equipment.
In addition, the 3D printer should be kept in a specific environment with the ventilation system and protect the material from the light.
PJ machines should also not be turned off unless there is a long time (months)
No print.
This includes a large waste of material by removing the liquid emptying nozzle;
Therefore, if PJ is used occasionally, maintenance costs will be higher than continuous printing.
The liquid for the SLA also needs to stay away from the light, but the machine does not need weekly maintenance such as SLS and BJ.
They can be used whenever a user wants to print an object and are easy to use.
The most complicated part of the process may be the removal of the printed material.
For BJ printers, the excess material and construction area must be manually vacuumed to remove the unincorporated powder.
For SLA printers, the printing tank must be carefully checked to ensure that there is no curing material in the tank, as it may interfere with the curing process of future printing.
Speed, accuracy and quality of manufacturing
Based on technology (SLA, PJ)
Provides the best precision and powderbased (SLS, BJ)
The printer is built the fastest.
That\'s why we chose the PJ process to create the thoracic aorta with root aneurysm for teaching purposes to ensure high
High-quality printing of details can be replicated in arterial geometry.
We actually have our 3D printed model to show as accurately as possible the shape of the body to the non-aortic lesions
Experience rich of surgery doctor
The use of a method to support the fiber lattice may reduce the surface quality and may require manual finishing to remove the marks that the surface does not want to appear, as described above.
37 However, a high resolution good machine that needs to support the fiber holder can still make objects with good surface roughness and clarity 39table 1).
In addition, the purity of the powder will affect the printing quality of SLS, 40 and the quality of the laser.
This is the case with any printer using UV curing (SLA, PJ)and sintering (SLS).
Powder sintering can also produce pores/voids in model 38, resulting in fragile structures with low stiffness 39 in BJ, contrary to the solid structures created by SLS.
In contrast, liquids tend to create more uniform material properties that are both hard and elastic.
41 Finally, the object needs to be well designed and positioned, regardless of the technology itself, to achieve optimal manufacturing.
According to the selected methods and parameters, changes in mechanical properties can be observed on the model, such as the heterosexual behavior corresponding to higher deformation resistance in the layer direction directly related to the building direction
42 rigid reduction can also be seen on the side of the object in contact with the support material, and the support material is not easy to expose to ultraviolet radiation curing during the polymerization process.
41 selecting the right printer to create the model 3d printing technology can be aligned with the predefined educational needs as shown below.
Teaching anatomy, patient education: models constructed with hard materials are often sufficient in order to teach anatomy and explain pathology.
Without the need for fine print definitions and the size of the model, FDM, a low-cost and easiest-to-access method, is undoubtedly the best option, otherwise we would recommend the SLA.
The model obtained by the SLA presents more details, so it would be better for small print models (
Coronary artery).
However, in the case of a model of the thoracic aorta with a root aneurysm, we emphasize the authenticity of the geometry with as many details as possible, which is why we need to use the most accurate 3D printing method: Pu.
It also allows us to easily change the color of the 3D printing model if needed.
Surgical planning and surgical review: surgical planning and surgical review do not necessarily require materials to have the same mechanical properties of biological tissues.
The hard material model can represent the anatomy well and again, it is emphasized that FDM and SLA may be your best choice.
Pre-program planning: pre-program planning models are more complex because they require materials that are mechanically representative of biological tissues.
This issue will be discussed in the next section and eventually all printing methods will be used.
The general concept of 3D printing is to use an object as a series of layers (see figure 11).
Each layer of the object (
Or a collection of objects)
With the same thickness, the thickness depends on the method selected and the accuracy of the machine.
In addition, the 3D printer is not necessarily limited to one material, for example, the material (A)
Can be used for an object consisting of Layer 1, Layer 2, and layer 3, while the second object (layer 4)
Can be made of this material (B).
This information must be defined by geometry files that were previously converted in stl that you created for each different object.
Some machines can even mix a material (or more)
However, for each kind of manufacturing, it is not possible to reproduce any kind of manufacturing precisely, resulting in changes or features of the model to another kind of manufacturing.
Figure 12 rapid prototyping method with red arrows indicating the direction of movement (x, y, z axes).
As shown in Figure 13, the supporting material cannot be deposited in a blank space, so models with prominence usually need to be filled or supported in the lattice (or scaffold)forms.
In addition, the filling material is designed to strengthen the structure during the printing process, thus avoiding the deformation of the model when the material is cured.
Download figureOpen in the new tabDownload powerpoint figure 13 structure, the highlighted part of the structure is filled with a lattice structure, supporting material, or non-cured material. With silk (FDM)or liquids (SLA)
The supporting material provides a grid that can be easily disassembled by hand with the tool;
However, in order to get a good finish, they usually leave unwanted impressions on surfaces that require additional polishing.
This step of the process is very subtle because it is possible to damage the model by losing the details of the geometry.
When the model is completed by dissolution, some supporting materials can also be easily removed, just like water-soluble pvc.
In PJ, the volume of the solidified wax support material used to fill the highlights.
For models that are easily soluble, engraving tools are usually used to clean models and water spray devices.
Otherwise, the solution bath can remove the filling required for printing on its own.
If your 3D printer makes a model using powder (BJ, SLS)
, The prominent part will be filled with uncured materials as support.
It\'s also easy to clean up.
It is important to note that models printed with undissolved grids or wax supporting materials can be very complicated to clean up, especially when it is not easy to approach the cavity with hands or tools.
Cost of printing: Easiest, easiest to get and cost for 3D printers, materials and technical support-
37, also the cheapest technology, see Table 1.
Prices usually go up from BJ to SLA, and finally SLS and PJ.
View this table: View the main features of the inline View pop-up table 1 Rapid prototyping method: Stereo Vision (SLA), polyJet (PJ)
Model of molten deposition (FDM)
Selective Laser Sintering (SLS)
Injection of adhesive (BJ)
With regard to material costs, FDM filaments once again become the cheapest material of all 3D printer types and should be considered in large print volumes where material performance and high print resolution are not the main concerns.
Also, they are easy to store and use, which leads to the majority of users
Friendly process.
The SLA and PJ can provide high resolution, but they are also much more expensive.
SLA is the highest resolution in all types of 3D printers, while PJ printers allow the use and mixing of multiple materials in one print.
BJ is also very cost-effective.
Effective, low overall cost of printing.
These powders are a little more expensive than the filaments of FDM, and nevertheless, their advantage is that they can be reused when they are not cured, but are used as support for previous printing.
Therefore, there is little waste of material compared to liquid and silk methods.
In addition, the BJ printer is fast and easy to use and maintain.
The main consumables components are cheap and easy to replace.
However, the BJ model is more vulnerable than FDM printing without processing.
In terms of technical requirements, the risk of a printer malfunction in a limited company is rare and easy to solve.
Common problems can be summarized as the melting or sliding problem of the blockage caused by the material through the nozzle, or when the part is not properly attached to the underheated print bed.
In a finite difference printer, most of the faults are caused by the design of the 3D model, not any problem with the machine itself.
The technology that requires the broadest range of technical support is PJ.
In order to avoid the blockage of the liquid from potential solidification in the nozzle, the technician should use all the loaded materials for weekly maintenance (
If there is no scheduled print)
Provides continuous material flow in the printer.
In addition, using very specific technology, multiple parts of the machine need to be cleaned frequently, and errors can easily damage the equipment.
In addition, the 3D printer should be kept in a specific environment with the ventilation system and protect the material from the light.
PJ machines should also not be turned off unless there is a long time (months)
No print.
This includes a large waste of material by removing the liquid emptying nozzle;
Therefore, if PJ is used occasionally, maintenance costs will be higher than continuous printing.
The liquid for the SLA also needs to stay away from the light, but the machine does not need weekly maintenance such as SLS and BJ.
They can be used whenever a user wants to print an object and are easy to use.
The most complicated part of the process may be the removal of the printed material.
For BJ printers, the excess material and construction area must be manually vacuumed to remove the unincorporated powder.
For SLA printers, the printing tank must be carefully checked to ensure that there is no curing material in the tank, as it may interfere with the curing process of future printing.
Speed, accuracy and quality of manufacturing
Based on technology (SLA, PJ)
Provides the best precision and powderbased (SLS, BJ)
The printer is built the fastest.
That\'s why we chose the PJ process to create the thoracic aorta with root aneurysm for teaching purposes to ensure high
High-quality printing of details can be replicated in arterial geometry.
We actually have our 3D printed model to show as accurately as possible the shape of the body to the non-aortic lesions
Experience rich of surgery doctor
The use of a method to support the fiber lattice may reduce the surface quality and may require manual finishing to remove the marks that the surface does not want to appear, as described above.
37 However, a high resolution good machine that needs to support the fiber holder can still make objects with good surface roughness and clarity 39table 1).
In addition, the purity of the powder will affect the printing quality of SLS, 40 and the quality of the laser.
This is the case with any printer using UV curing (SLA, PJ)and sintering (SLS).
Powder sintering can also produce pores/voids in model 38, resulting in fragile structures with low stiffness 39 in BJ, contrary to the solid structures created by SLS.
In contrast, liquids tend to create more uniform material properties that are both hard and elastic.
41 Finally, the object needs to be well designed and positioned, regardless of the technology itself, to achieve optimal manufacturing.
According to the selected methods and parameters, changes in mechanical properties can be observed on the model, such as the heterosexual behavior corresponding to higher deformation resistance in the layer direction directly related to the building direction
42 rigid reduction can also be seen on the side of the object in contact with the support material, and the support material is not easy to expose to ultraviolet radiation curing during the polymerization process.
41 selecting the right printer to create the model 3d printing technology can be aligned with the predefined educational needs as shown below.
Teaching anatomy, patient education: models constructed with hard materials are often sufficient in order to teach anatomy and explain pathology.
Without the need for fine print definitions and the size of the model, FDM, a low-cost and easiest-to-access method, is undoubtedly the best option, otherwise we would recommend the SLA.
The model obtained by the SLA presents more details, so it would be better for small print models (
Coronary artery).
However, in the case of a model of the thoracic aorta with a root aneurysm, we emphasize the authenticity of the geometry with as many details as possible, which is why we need to use the most accurate 3D printing method: Pu.
It also allows us to easily change the color of the 3D printing model if needed.
Surgical planning and surgical review: surgical planning and surgical review do not necessarily require materials to have the same mechanical properties of biological tissues.
The hard material model can represent the anatomy well and again, it is emphasized that FDM and SLA may be your best choice.
Pre-program planning: pre-program planning models are more complex because they require materials that are mechanically representative of biological tissues.
This issue will be discussed in the next section and eventually all printing methods will be used.
The selection of 3D printing materials is directly related to the 3D printing process and the selection of printers, as well as the needs of models.
All the information developed in the following paragraphs is summarized and reorganized in table 2.
View this table: view inline View pop-up table 2 3D printing techniques and materials involved in surgical training model manufacturing, their simulated body parts, purpose, requirements and machine human bones using rigid materials are printed through 3D the simplest biological tissue to replicate, because most materials are rigid.
The most common option is still acrylic-Ding benzene (ABS)
BJ also used FDM20 27 43, but Beijing also used powder from gypsum board 27 and hydrogen quinine 23, as well as polyamide to mix polyamide with glass beads.
22 ABS is the same plastic used in most home water pipes and the most affordable material for 3D printing.
It turns out that despite the softness of the material, it is a suitable bone replacement with good visual and tactile effects that can practice drilling at minimal cost.
Cohen and Reyes argue that the benefits of training will be felt even if the mechanical properties do not exactly match the bones.
This study is a perfect example of the fact that tissue Fidelity does not necessarily need to be fully realistic, and the purpose and requirements of the model are absolutely necessary when choosing the right material.
In the context of pre-program planning, rigid materials may also be sufficient, which has proved that it can improve the way surgeons think, interpret, evaluate a program and face complex situations by simulating all steps in advance.
2 19 44 lack of image 14 and anatomical consistency (
Charcot foot syndrome)
45, and the hard visualization of 3D geometry through a 2D display, 10 may complicate the surgical strategies that the 3D printing model can achieve.
After that, the same rigid model can be used for localization during surgery.
46 in addition, Levi et al28 highlights the importance of several visits by residents to memorize the stage of surgery.
On the other hand, the physical and graspable models help trainees to familiarize themselves with human anatomy and infinite pathology for better understanding, 11 47 tactile and visual 3D appreciation.
Therefore, when the operation time is shortened to two hours, the accuracy of the program will be higher and the quality of diagnosis will be improved.
30, 48 years old and the risk of complications and trauma in the patient.
To better understand and visualize multiple situations, 2 models can also be designed as removable structures.
49 flexible materials most 3D printing materials lack the realism of fully imitating soft human biological tissues;
As a result, post-processing may be required to soften the printing structure.
For example, the cartilage tissue used for Anatomy and drilling requires a liquid coating to increase the physical strength of the structure created by BJ, while the penetration of the elastic resin is intended to increase its flexibility.
27 similarly, BJ was used for tumors in the context of surgical simulation, 26 arteries were used for the implementation of catheter valve replacement, 17 for liver segment 50 and heart 17 51 for the teaching of human anatomy.
In contrast, SLA has the ability to manufacture flexible hearts made of polyurethane suitable for cutting and stitching practices without post-processing.
9 Similarly, the PJ52 also replicated the cartilage trachea, providing rubber
The flexibility of the structure, such as arteries, 16 36 soft tissues, 53 valve 18, and brain aneurysm, can be controlled as with materials mixed with rigid photopolymers.
31 the trachea, arteries, and soft tissue are created to be as real as possible, while the valve is used to learn the catheter
Surgical equipment based on intervention and evaluation;
In addition, the aneurysm is to learn how to clip the artery.
Print with multiple materials as needed, several materials (
Color, properties, texture)
A proper Phantom may need to be created.
Waran etal29 chose to use the multi-layer material pajamas machine
A base model made of rigidity and soft tissue (
Bone, spine, tumor, normal brain).
Similarly, Wang et al. manufactured a material made of rigid fibers embedded in flexible materials to control the performance of printed composites.
Chan et al. 27 manufactured the hard structure of the bone and softer cartilage tissue with different materials and processes, respectively, to finally realistically assemble the replicated head and neck.
Finally, a three-layer polyurethane coating was added by Hochman et al to simulate the hard spine membrane of the temporary bone model for better tissue fidelity.
Multi-material composites may be the future of 3D printing models, as none of the materials currently available can simulate elasticity and biological tissue.
Therefore, printing materials containing fibers are being explored to fully control the mechanical properties of the model.
Mechanical testing can be performed to analyze the biological mechanical response of human tissues by cutting, compressing or tearing materials.
So, more
Material composites can be manufactured according to the selected material\'s ability to simulate the mechanical properties of human tissues.
Recently, our team has been focusing on mechanical testing of human aortic tissue, 55 providing the necessary data for the manufacture and testing of materials that ultimately have tissue fidelity.
Rigid material bones are the simplest biological tissues copied through 3D printing, as most materials are rigid.
The most common option is still acrylic-Ding benzene (ABS)
BJ also used FDM20 27 43, but Beijing also used powder from gypsum board 27 and hydrogen quinine 23, as well as polyamide to mix polyamide with glass beads.
22 ABS is the same plastic used in most home water pipes and the most affordable material for 3D printing.
It turns out that despite the softness of the material, it is a suitable bone replacement with good visual and tactile effects that can practice drilling at minimal cost.
Cohen and Reyes argue that the benefits of training will be felt even if the mechanical properties do not exactly match the bones.
This study is a perfect example of the fact that tissue Fidelity does not necessarily need to be fully realistic, and the purpose and requirements of the model are absolutely necessary when choosing the right material.
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