Please note the democratiz3D service was previously named "Imag3D"
In this tutorial you will learn how to quickly and easily make 3D printable bone models from medical CT scans using the free online service democratiz3D®. The method described here requires no prior knowledge of medical imaging or 3D printing software. Creation of your first model can be completed in as little as 10 minutes.
You can download the files used in this tutorial by clicking on this link. You must have a free Embodi3D member account to do so. If you don't have an account, registration is free and takes a minute. It is worth the time to register so you can follow along with the tutorial and use the democratiz3D service.
>> DOWNLOAD TUTORIAL FILES AND FOLLOW ALONG <<
Both video and written tutorials are included in this page.
Before we start you'll need to have a copy of a CT scan. If you are interested in 3D printing your own CT scan, you can go to the radiology department of the hospital or clinic that did the scan and ask for the scan to be put on a CD or DVD for you. Figures 1 and 2 show the radiology department at my hospital, called Image Management, and the CDs that they give out. Most radiology departments will have you sign a written release and give you a CD or DVD for free or with a small processing fee. If you are a doctor or other healthcare provider and want to 3D print a model for a patient, the radiology department can also help you. There are multiple online repositories of anonymized CT scans for research that are also available.
Figure 1: The radiology department window at my hospital.
Figure 2: An example of what a DVD containing a CT scan looks like. This looks like a standard CD or DVD.
Step 1: Register for an Embodi3D account
If you haven't already done so, you'll need to register for an embodi3d account. Registration is free and only takes a minute. Once you are registered you'll receive a confirmatory email that verifies you are the owner of the registered email account. Click the link in the email to activate your account. The democratiz3D service will use this email account to send you notifications when your files are ready for download.
Step 2: Create an NRRD file with Slicer
If you haven't already done so, go to slicer.org and download Slicer for your operating system. Slicer is a free software program for medical imaging research. It also has the ability to save medical imaging scans in a variety of formats, which is what we will use it for in this tutorial.
Next, launch Slicer. Insert your CD or DVD containing the CT scan into your computer and open the CD with File Explorer or equivalent file browsing application for your operating system. You should find a folder that contains numerous DICOM files in it, as shown in Figure 3. Drag-and-drop the entire DICOM folder onto the Slicer welcome page, as shown in Figure 4. Click OK when asked to load the study into the DICOM database. Click Copy when asked if you want to copy the images into the local database directory.
Figure 3: A typical DICOM data set contains numerous individual DICOM files.
Figure 4: Dragging and dropping the DICOM folder onto the Slicer application. This will load the CT scan.
Once Slicer has finished loading the study, click the save icon in the upper left-hand corner as shown in Figure 5. One of the files in the list will be of type NRRD. make sure that this file is checked and all other files are unchecked. click on the directory button for the NRRD file and select an appropriate directory to save the file. then click Save, as shown in Figure 6.
Figure 5: The Save button
Figure 6: The Save File box
The NRRD file is much better for uploading then DICOM. Instead of having multiple files in a DICOM data set, the NRRD file encapsulates the entire study in a single file. Also, identifiable patient information is removed from the NRRD file. The file is thus anonymized. This is important when sending information over the Internet because we do not want identifiable patient information transmitted.
Step 3: Upload the NRRD file to Embodi3D
Now go to www.embodi3d.com, click on the democratiz3D navigation menu and select Launch App, as shown in Figure 7. Drag and drop your NRRD file where indicated. While NRRD file is uploading, fill in the "File Name" and "About This File" fields, as shown in Figure 8.
Figure 7: Launching the democratiz3D application
Figure 8: Uploading the NRRD file and entering basic information
Figure 9: Basic information fields about your uploaded NRRD file
Next, turn on democratiz3D Processing by selecting the slider under democratiz3D Processing. Make sure the operation CT NRRD to Bone STL is selected. Leave the default threshold of 150 in place. Choose an appropriate quality. Low quality produces small files quickly but the output resolution is low. Medium quality is good for most applications and produces a relatively good file that is not too large. High quality takes the longest to process and produces large output files. Bear in mind that if you upload a low quality NRRD file don't expect the high quality setting to produce a stellar bone model. Medium quality is good enough for most applications.
If you wish, you have the option to specify whether you want your output file to be Private or Shared. If you're not sure, click Private. You can always change the visibility of the file later. If you're happy with your settings, click Save & Submit Files. This is shown in Figure 10.
Figure 10: Entering the democratiz3D Processing parameters.
Step 4: Review Your Completed Bone Model
After about 10 to 20 minutes you should receive an email informing you that your file is ready for download. The actual processing time may vary depending on the size and complexity of the file and the load on the processing servers. Click on the link within the email. If you are already on the embodied site, you can access your file by going to your profile. Click your account in the upper right-hand corner and select Profile, as shown in Figure 11.
Figure 11: Finding your profile.
Your processed file will have the same name as the uploaded NRRD file, except it will end in "– processed". Renders of your new 3D model will be automatically generated within about 6 to 10 minutes. From your new model page you can click "Download this file" to download. If you wish to share your file with the community, you can toggle the privacy setting by clicking Privacy in the lower right-hand corner. You can edit your file or move it from one category to another under the File Actions button on the lower left. These are shown in Figure 12.
Figure 12: Downloading, sharing, and editing your new 3D printable model.
If you wish to sell your new file, you can change your selling settings under File Actions, Edit Details. Set the file type to be Paid, and specify a price. Please note that your file must be shared in order for other people to see it. This is shown in Figure 13. If you are going to sell your file, be sure you select General Paid File License from the License Type field, or specify your own customized license. For more information about selling files, click here.
Figure 13: Making your new file available for sale on the Embodi3D marketplace.
That's it! Now you can create your own 3D printable bone models in minutes for free and share or sell them with the click of a button.If you want to download the STL file created in this tutorial, you can download it here. Happy 3D printing!
Dear Community Members,
After many months of work, we are happy to announce the addition of a feature that will allow you to sell medical models you have designed on Embodi3D.com. While we always have encouraged our members to consider allowing their medical STL files to be downloaded for free, we understand that when a ton of time is invested in creating a valuable and high-quality model, it is reasonable to ask for something in return. Now Embodi3D members have two options: 1) You can share your medical models for free, or 2) you can charge for them. We hope these two options encourage more sharing and file uploads. The more models available, the more it helps the medical 3D printing community.
For more details on how to sell your medical masterpieces on Embodi3D, go to the selling page.
Thanks, and happy 3D printing!
In this tutorial we will learn how to use the free medical imaging conversion service on embodi3D.com to create detailed anatomic muscle and skin 3D printable models in STL file format from medical CT scans. Muscle models show the detailed musculature by subtracting away the skin and fat. Even when created from a scan of an obese person, the model looks like it comes from a bodybuilder, Figure 1A. Skin models show an exact replica of the skin surface. The finest details are captured, including wrinkles and veins underneath the skin. Hair however is not captured in a CT scan and thus the model does not have any hair, Figure 1B.
Figure 1A (left): A muscle 3D printable model. Figure 1B (right): A skin 3D printable model
These models can be used for a variety of purposes such as medical and scientific education and research. Additionally, the skin models can be used to re-create a person's likeness in 3D from a medical scan. If you have had a CT scan of the head, you can create a lifelike replica of your head. You can create replicas of your friends, family, or even pets if they have had a medical CT scan. Alternatively, if you have a loved one who passed away but had a CT scan prior to death, you can use the scan to re-create an exact replica of their face. Even scans that are years old can be used for this purpose. Some people may consider this to be a little creepy, so if you are considering doing this think carefully first.
Before proceeding please register for an embodi3D.com account if you haven't already. You will need an account to use the service.
It is highly recommended that you download the associated file pack for this tutorial so that you can follow along with the exact same files that are used in this tutorial.
>> DOWNLOAD THE FREE FILE PACK BY CLICKING HERE <<
If you are interested in learning how to use the free embodi3D.com service, see my prior tutorials on creating bone models, processing multiple models simultaneously, and sharing and selling your models on the embodi3D.com website.
If you are interested in converting your own CT scan or that of a friend or family member, you can go to the radiology department of the hospital or clinic that did the scan and ask for the scan to be put on a CD or DVD for you. Figure 2 shows the radiology department at my hospital, called Image Management, and the CDs that they give out. Most radiology departments will have you sign a written release and give you a CD or DVD for free or with a small processing fee. If you are a doctor or other healthcare provider and want to 3D print a model for a patient, the radiology department can also help you. There are multiple online repositories of anonymized CT scans for research that are also available. If you have downloaded the file pack for this tutorial, example CT scans are included
Figure 2A, the Image Management (radiology) department at my hospital, where you can pick up a DVD of your CT scan as shown in Figure 2B (right). My hospital does this for free, but some may charge a trivial fee.
PART 1: Creating a Muscle STL model from NRRD File
Before we begin please bear in mind that this process only works for CT scan images. It will not work for MRI images. Before proceeding please check that the scan you wish to convert is a CT (CAT) scan!
Step 1: Convert Your CT scan to an Anonymized NRRD File with 3D Slicer
Open 3D Slicer. If you don't have the software program you can download it for free from slicer.org. Once Slicer has opened, take the folder from the download pack that is called STS_004. This folder contains anonymized DICOM images from a CT scan of the legs of a 24-year-old woman who had a muscle tumor. Drag and drop the entire folder onto the Slicer window, as shown in Figure 3. Slicer will ask you if you want to load the images into the DICOM database. Click OK. Slicer will also ask you if it should copy the images into the database, click Copy. Slicer will take about one minute to load the scanned.
Figure 3: Drag-and-drop the STS_004 DICOM folder from the file pack onto the Slicer window
Next, load the scan into the active wor king area in slicer. If the DICOM browser is not open, click on the Show DICOM browser button, as shown in Figure 4. Click on the STS_004 patient and series, and click the Load button, as shown in Figure 4. The leg CT scan will now load into the active seen within Slicer, as shown in Figure 5.
Figure 4: Open the DICOM browser and load the study into the active seen
Figure 5: The leg CT scan is shown in the active seen
Step 2: Trim the Scan so that only the Right Thigh is included.
Click on the Volume Rendering module from the Modules drop-down menu as shown in Figure 6. Turn on volume rendering by clicking on the eyeball button, as shown in Figure 7. Then, center the model in the 3D pane by clicking on the crosshairs button, Figure 7. If you don't have the same window layout as shown in Figure 7, you can correct this by clicking on the Four-Up window layout from the window layout drop-down menu, as shown in Figure 8.
Figure 6: Turn on the volume rendering module
Figure 7: Center the rendered volume.
Figure 8: Make sure you are in the Four-Up window layout
Next we are going to crop the volume so that we exclude everything other than the right knee and thigh. From the modules menu, select All Modules, Crop Volume, as shown in Figure 9. Turn on ROI visibility by clicking on the eyeball button, as shown in Figure 10. Then, move the region of interest box so that it only encapsulates the right thigh, as shown in Figure 10. You can adjust the size of the box by grabbing on the colored circular handles and moving the sides of the box as needed.
Figure 9: The Crop Volume module.
Figure 10: Turning on and adjusting the crop volume ROI (Region Of Interest)
Once the crop volume ROI is adjusted to the area that you want, perform the crop by clicking on the Crop button, Figure 11.
Figure 11: the Crop button.
The new, smaller volume that encompasses the right fight and knee has been assigned a cryptic name. The entire scan had a name of "2: CT IMAGES – RESEARCH," and the new thigh volume has a name "2: CT IMAGES-RESEARCH-subvolume-scale_1." That's a mouthful and I want to rename it to something more descriptive. I'm going to select the Volumes module, and then select the "2: CT IMAGES-RESEARCH-subvolume-scale_1" from the Active Volume drop-down menu. Then, from the same drop-down menu I'm going to select "Rename Current Volume". Type in whatever name you want. In this case I'm choosing "right thigh."
Figure 12: Renaming the newly cropped volume.
Step 3: Save the right thigh volume as an anonymized NRRD file.
Click on the Save button in the upper left-hand corner. The save window is then shown. All the checkboxes on the left except for the one that corresponds to the right by. Make sure the file format for this line says NRRD (.nrrd). Make sure you specify the proper directory you want the file to be saved as. When you are satisfied click on save. This is demonstrated in Figure 13. In the specified directory you should see a called right thigh.nrrd.
Figure 13: The save file options.
Step 4: Upload the NRRD file to embodi3D.com
Make sure you are logged into your embodi3D.com account. Click on Imag3D from the nav bar, Launch App. Then drag-and-drop your NRRD file onto the upload pain, as shown in Figure 14.
Figure 14: Uploading the NRRD file to embodi3D.com.
Figure 15: File processing options.
Step 5: Download your new STL file after processing is completed.
In about 5 to 15 minutes you should receive an email that says your file has finished processing and is ready to download. Follow the link in the email or access the new file via your profile on the embodi3D.com website. Your newly created STL file should have several rendered thumbnails associated with it on its download page. If you want to download the file click on the Download button, as shown in Figure 16.
Figure 16: the download page for your new muscle STL file
I opened the file in AutoDesk MeshMixer to have another look at it, and it looks terrific, as shown in Figure 17. This file is ready to 3D print!
Figure 17: The final 3D printable muscle model.
PART 2: Creating a Skin Model STL File Ready for 3D Printing
Creating a skin model is essentially identical to creating the muscle model, except instead of choosing the CT NRRD to Muscle STL on the embodi3D.com service, we choose CT NRRD to Skin STL.
Step 1: Load DICOM image set into Slicer
Launch Slicer. From the tutorial file pack drag and drop the MANIX folder onto the Slicer window to load this head and neck CT scan data set. This is shown in Figure 18.
Figure 18: Loading the head and neck CT scan into Slicer. It may take a minute or two to load. From the DICOM browser, click on the ANGIO CT series as shown in Figure 19.
Figure 19: Loading the ANGIO CT series from the MANIX data set
Step 2: Skip the trimming and crop volume operations
In this case we don't need to trim and crop a volume as we did with the muscle file above. We can skip Step 2.
Step 3: Save the CT scan in NRRD format.
Just as with the muscle file above, save the volume in NRRD format. Click on the save button, make sure that the checkbox for the nrrd file is selected and all other checkboxes are deselected. Specify the correct directory you want the file to be saved in, and click Save.
Step 4: Upload your NRRD file of the head to the embodi3D website.
Just as with the muscle file process as shown above, upload the head NRRD file to the embodi3D.com website. Enter in the required fields. In this case, however, under Operation choose the CT NRRD to Skin STL operation, as shown in Figure 20.
Figure 20: Selecting the CT NRRD to Skin STL file operation
Step 5: Download your new Skin STL file
After about 5 to 15 minutes, you should receive an email that says your file processing has been completed. Follow the link in the email or look for your file in the list the files you own in your profile. You should see that your skin STL file has been completed, with several rendered images, as shown in Figure 21. Go ahead and download your file. You can then check the quality of your file in Meshmixer as shown in Figure 22. In this instance everything looks great and the file is error free and ready for 3D printing.
Figure 21: The download page for your newly created 3D printable skin STL file.
Figure 22: Opening the file in Meshmixer for quality control checks. The file is error free and incredibly lifelike. It is ready for 3D printing.
Thank you very much! I hope you enjoyed this tutorial. If you use this service to create 3D printable models, please consider sharing your models with the embodi3D community. Here is a detailed tutorial that I wrote on exactly how to do this. This community is built on medical 3D makers helping each other. Please share the models that you create!
Biofabrication – the combination of mechatronics and biology – is no longer featured in science fiction movies. Currently, the clinical landscape is now using biofabrication through 3D bioprinting to treat different medical conditions that are difficult to medicate using conventional medical procedures.
So what does biofabrication do? If you are sick and in need of a new body part, biofabrication can build it for you. A good example of the application of biofabrication is the cochlear implant which originated in Australia. Also, the country is also involved in the clinical breakthroughs of the implanted jawbone and heel which made them a world leader in 3D biofabrication.
3D biofabrication has a lot of promising features. Aside from being used in creating cochlear and orthopedic implants, biofabrication can also be used in other industries to design new treatment procedures and products.
Moreover, the future of 3D biofabrication looks very promising for future bioengineers. Many investors are starting spin-out companies that employ 3D printing for different applications. This can lead to a wave of academic institutions fortifying its system to provide better education to students who want to take biofabrication in the future. For instance, establishing Masters courses for 3D biofabrication can extend help to the future biofabricators by providing them with the skills needed to operate in this field.
The role of biofabrication in future societies is very big. It can help extend lives by making complex surgical procedures seem easy as well as making body parts readily available to patients. It is science fiction slowly being turned to reality.
3D printing is an essential tool in the modern medical technology as it is used in multitude of applications. One testament of the efficacy of 3D printing technology was its use on a double knee replacement surgery in China.
Doctors from Handan, China used 3D printing technology to repair the legs of a young patient requiring double knee surgery. Suffering from the condition called genu varum deficiency, the patient is characterized having bow legs due to the inward angulation of the knee that resulted to a 43-degree angle of the legs.
Thanks to 3D printing, the doctors were able to find a solution by using 3D printing technology. The doctors were able to create a 1:1 scale replica of the patient’s leg as well as knee joints to fully understand the condition. They also used the replica to plan the best course of action to treat the patient.
With the help of the 3D printed replica, the doctors were able to decide that a double knee replacement surgery is necessary. They also used the replica to practice prior to the operation thus reducing the risk for the patient during and after the surgery.
Dr. Han Shoujiang, Director of No. 3 Department in the said hospital, noted that the 3D printing technology is one of a kind as it allows surgeons to simulate the surgical procedure and also create correct surgery plan. Thanks to 3D printing technology and the knowledge of the doctors, the patient was able to walk for the first time in many decades.
It still sounds like Science Fiction — the next development in 3D printed science is a micro robotic fish.
Medical researchers from the University of California, San Diego have just started testing a new 3D printed nanotechnology that could be used for drug delivery or even removal of toxins (such as bee venom) from the body.
Published in the August issue of the journal Advanced Materials, a team of researchers from the NanoEngineering Department led by Shaochen Chen and Joseph Wang 3D printed micro fish that size up at 30 microns thick and 120 microns long.
Through a series of tests, the team were able to find the micro fish effective in purifying water that was contaminated with a toxin. Once in action, the fish glow red and swim around to completely decontaminate the water.
A New Method of Micro-Manufacture
The micro fish were developed using a high resolution 3D printer and a technique called microscale continuous optical printing (COP), which enables them to print hundreds of fish in just a few seconds. The fish are made of tiny pieces of platinum in the tail that form a reaction when in contact with hydrogen peroxide. If they are placed in hydrogen peroxide, the reaction causes their tails to move so that they start to swim. It is also possible for the researchers to use other particles in addition to platinum when producing the fish, such as chemicals that identify and eliminate toxins.
The method is still very new, so it might take a while before we see the results applied to medical practice.
High Hopes for Tiny Fish
Wei Zhu, a nanoengineering Ph.D. student and co-author on the study, said, "We have developed an entirely new method to engineer nature-inspired microscopic swimmers that have complex geometric structures and are smaller than the width of a human hair. With this method, we can easily integrate different functions inside these tiny robotic swimmers for a broad spectrum of applications.”
Jinxing Li, another researcher on the project, said in a press release, “This method has made it easier for us to test different designs for these microrobots and to test different nanoparticles to insert new functional elements into these tiny structures. It’s my personal hope to further this research to eventually develop surgical microrobots that operate safer and with more precision.”
The groundbreaking project has received support by the NIS as well as the Defense Threat Reduction Agency-Joint Science and Technology Office for Chemical and Biological Defense.
Photo Credits: Popular Science Perfect Science
There are many innovations in 3D printing technology in the medical world. Aside from being used in creating casts for orthopedic patients, it is also being used by pediatric neurosurgeons to create model body parts of their patients.
Surgeons from the Boston Children’s Hospital are now using 3D printing to create 3D models of anatomies of pediatric patients suffering from cerebrovascular malformations which is characterized by having abnormalities in the blood vessels found in the brain.
The pediatric patients, due to the unique brain anatomies, are very difficult to operate on. Dr. Edward Smith, co-director of the Cerebrovascular Surgery and Intervention Center said that the operation may be impossible without the help of 3D printing
The use of 3D printed models can give an intuitive feel of the treatment and it also reduces the risks during the actual operation. To create the 3D printed brain models, a 3D resin printer was use. The data of the pediatric patients was obtained through magnetic resonance as well as MR arteriography data which allowed doctors to see the malformations of the vessels. It is interesting to take note that 3D printing was able to produce 98% accurate models of the patients’ brains.
The use of 3D printing technology in creating accurate and precise brain models allowed the doctors to have a 30-minute reduction of the surgery time which may not sound like a lot of time but it means a dramatic difference and less exposure to anesthesia.
3D printing has become a regular tool in the medical industry as it allows doctors to do their jobs with accuracy and less risk to their patients.
3D printing is used widely in additive manufacturing and medical technology. While it is used to create medical models, it is now used to create better pills. The US Food And Drug Administration recently approved the first ever 3D-printed pill that is used to treat patients suffering from epilepsy. The pill was created by an Ohio-based company called Aprecia Pharmaceuticals.
The pill, called Spritam, is made using the ZipDose technology which is a process that makes the pill porous thus it dissolves easily once taken. This drug is very beneficial for patients who have difficulty in swallowing, making it great for patients who are suffering from epileptic episodes.
Aside from being easily swallowed, the company noted that the use of 3D printing technology allows them to pack high doses of drug in the tablet; which is quite beneficial since most epileptic patient loath taking large sized medicines. Moreover, this new 3D printed drug is very convenient because patients and their caregivers no longer need to measure the dose since each dose is already packed individually. This is very convenient when emergency situations arise.
To create this drug, special 3D printers were used to create them. Conventional 3D printers use polymers but the specially designed 3D printers use chemical compounds to produce the drugs. This clearly shows that 3D printing technology is very versatile.
Currently, the drug is not yet available to the public and the drug will go on sale during the first quarter next year but the company is planning to make more formulations using the 3D printing technology.
The ability to create affordable prosthetics for humans by 3D printing has been in the news since shortly after the it was invented. Now, more animals are benefitting from the technology. Most recently, several birds have successfully joined this growing club of animals with 3D printed prosthetics. But damaged beak most often means death since the birds can’t eat properly, making this 3D printed fix a life saving solution.
Grecia from Costa Rica
Take Grecia, a toucan from Costa Rica. He was a neighborhood pet, where people fed him regularly. This is why he didn’t fly away when approached by a group of kids who snapped off his top beak. Toucans not only use their beaks to eat, but also to regulate body temperature, so Grecia was in a dangerous situation.
Locals took Grecia to the Zoo Ave Animal Rescue Center, where workers campaigned for money and help to create a prosthetic for him. Ewa Corps designed him a two piece 3D beak, with a fixed part and removable piece so that it could be cleaned or replaced when Gercia outgrows it.
Grecia isn’t the only bird benefitting from a 3D printed beak. In the US, a penguin and an eagle have successfully adapted to the prosthetic.
A Chinese Pelican’s Loss for Love
One Chinese White Pelican living at the Dalian Forest Zoo in China ended up with a partially shattered beak after a courtship fight with other pelicans. The bird couldn’t open and close his mouth, let alone eat, and he was shunned by the rest of his flock. Doctors tried several times to fix the damaged beak with aluminum foil but it could not withstand the bird’s activity. They decided to enlist the help of Bao Shu of the Dalian Ruling Science and Technology Company to create a 3D prosthetic.
In White Pelicans, the beak grows tissues that connect inside the mouth, so that removing the broken section of the beak and replacing it with a prosthetic wouldn’t be possible. So instead, doctors 3D printed a board with matching size and texture of the pelican’s beak, and screwed it into the existing beak to hold it in place. The prosthetic took four prototypes, but it was a success, and the pelican was already able to eat again the day after surgery.
A Green Bill from Brazil
The most recent success story of a bird with a new beak is for a Green Billed Tucon, who lost most of his upper beak after flying into a window.
“This toucan could not eat, so if we did not do the operation he literally starve to death,” said veterinarian Roberto Fecchio. “We had to think of something to help him. It is voluntary work involving many people, a multidisciplinary team and we are learning too along the way.”
Doctors replicated part of the bird’s beak using photogrammetry, and printed a prosthetic that now allows the bird to lead a normal life.
Photo Credits: The Telegraph 3DPrint.com 3ders.org
3D printing has been utilized over the past months to create innovative medical devices and implants. Recently, the dental industry has also utilized 3D printing technology in order to create different teeth implants.
One of the companies that made important developments by using 3D printing technology is DENTCA. DENTCA produced the first-ever FDA-approved 3D-printed denture base. The material is made from light-cured resin ejected from a specialized 3D printer. The denture bases created using this technology passed for cytotoxicity, genotoxicity, irritation as well as biocompatibility. This means that the denture is completely safe.
Another advantage of DENTCA is that it is twice faster than traditional means of producing dentures thus patients don’t need to wait to have their dentures. Conventional methods for making dentures need 30 days for the turnaround but DENTCA patients only need 5 days. Moreover, this technology is also very precise and accurate; thus eliminating any human error and dentures will always have a perfect fit.
Dr. Jason Lee, the creator of the DENTCA technology mentioned that this new denture base can revolutionize the entire dental world. Moreover, DENTCA’s CEO Sun Kwon also noted that this new development can pave way for the doctors to one day create customized dentures right in their offices. The company made a very big achievement that can play a very important role in the denture industry. It will be soon when we will see other dental companies jumping on the bandwagon because 3D printing technology is really beneficial not only for dental companies but also for patients and dentists.
When it’s time to present forensic evidence to a judge and jury, prosecutors have traditionally relied on photographs and other visual methods to display evidence. Today, forensic anthropologists are embracing a much more detailed visual aid—with a little help from 3D Printing.
3D Printing for Forensic Evidence
In the case of homicide, there’s no better way to clearly present evidence to a jury than by showing them the actual bones in question, but that’s not considered best practice for an unbiased jury. “..presenting human remains can be disturbing for some individuals, which in turn could lead to prejudicing the jury,” said biological anthropologist David Errickson. There are also risks to the specimens. “…handing bones in courtroom environments could cause bone degradation, which could damage the very forensic evidence of interest.”
Forensic scientists have begun to get around these road blocks by scanning and 3D printing accurate bone samples to present to juries. While CT scanning and X-rays have already been used in the field for years, 3D printers have only recently become an affordable option. Already the printed bones have proved helpful in murder cases. UK prosecutors secured a murder conviction last May by 3D printing two humerus fragments, one found in a man’s house and the other from a suitcase found in a canal. They used software to demonstrate that the two fragments fit together, and to show the matching saw cuts on each.
Printing models of bones is only the beginning for 3D printing in forensic anthropology. Creating casts of footprints is another common piece of evidence used in court. Though often, first responders to a crime scene can only capture photos of footprints, so that making a cast is impossible. Now, advanced photogrammetry software and a digital camera are all they need to 3D print a footprint cast from a photo.
3D scanning can also help with the identification of human remains. The Central Identification Laboratory of the Joint POW/MIA Accounting Command is doing just that by scanning and printing 3D models of remains and superimposing the model with photographs of different faces to create a match. Their goal is to accurately identify remains of American soldiers found after military conflicts.
Traditionally, documenting fingerprints found at a crime scene is done by collecting them using powder and tape, and then creating a high resolution image. Scanning and printing blown up models of these fingerprints is another new application of 3D technology. It makes it easier for examiners to ensure an accurate match, as all finger prints have highly detailed surfaces with unique curves, ridges, and pores, which become more visible with larger models. This not only allows investigators to make comparisons, but also helps prosecutors demonstrate similarities to a judge and jury.
Photo Credits: Forbes Times Higher Education Forensic Magazine
There are many applications of 3D printing in the medical industry. As a matter of fact, experts in 3D printing made innovations for the different applications of 3D printing. One such innovation is the new 3D printed cast that can heal broken bones and also double as a Bluetooth speaker.
This cast is called BoomCast which is embedded with electronics and sensors so that it can be used as a Bluetooth speaker. Moreover, the electronics also allow doctors to monitor the condition of their patients wherever they may be.
This smart medical cast was invented by Mike North. As a frequent traveler, it made it difficult for him to travel with conventional casts . He used 3D printing technology to create the BoomCast to allow him to travel as well as bear weight on the affected foot.
BoomCast is equipped with stamp-sized processors which gives this highly modern cast good computational prowess. This cast also include an accelerometer, gyroscope, magnetometer and several pressure sensors.
This medical device can measure leg movements as well as the amount of swelling in the affected leg. The data collected from the sensors is transmitted to Google’s Firebase in real time and is then shared to the doctor of the patient for monitoring.
Unfortunately, this product will not be made available to consumers any time soon. However, the developers made this project open source so that it can be made by people who have their own consumer-type 3D printers at home. Since it is an open-source project, other people can also contribute to the improvement of such product in the future.
A full skull reconstruction surgery is very difficult to achieve using conventional surgical procedures. However researchers from the Second People’s Hospital of Hunan Province in China performed the first ever full skull reconstruction surgery using 3D printing technology.
The patient was a 3 year old girl suffering from a rare condition called congenital hydrocephalus which caused her head to grow four times its normal size. This condition can also cause problems with brain development. Moreover, the fluid in the brain creates such huge pressure that is detrimental to brain development and functions.
The lead surgeon, Dr. Bo said that the patient will not have survived if she did not get the treatment. The first step to treating her is to remove the infection within her head and application of skin grafting surgery as well as insert a shunt to remove the infection, while also draining the fluid from her brain. However, this is just a temporary solution to her problem.
She also underwent a CT scan so that doctors can create skull models for 3D printing. The model was also used by the doctors to create the titanium mesh skull implants that will be used to correct the size of the head of the patient.
During the procedure, her scalp was removed from her skull and immersed in a saline solution. Drainage tubes were also placed in the head to remove the cerebrospinal fluid. Once the fluids were removed, the surgeons inserted the titanium implants into her head to recreate a new skull. After the grueling surgery, the patient is expected to make a full recovery. The success of this surgery made 3D printing very promising for neurosurgery.
Researchers at the ARC Centre of Excellence for Electromaterials Sciences (ACES) at the University of Wollongong in Australia have developed a structure of neural cells using 3D printing that acts much like human brain tissue.
With around 86 billion nerve cells, the human brain is incredibly complex and multi-faceted. This is the main reason the brain is hardly understood compared to other organs in the body. But recent developments in 3D printing brain tissue could help scientists learn so much more about the mysterious organ.
The possibility of creating a “bench-top brain’ with these tissues will not only teach us more about how the brain functions, but it will also serve as a preferred test bed for experimental drugs and electroceuticals. Pharmaceutical companies largely rely on testing therapeutic drugs with animal subjects, spending millions of dollars only to learn that the drugs affect the human brain much differently. If large amounts of this new tissue become available at an affordable price, then companies can perform tests that will not only increase drug safety, but also result in better drugs than they would have achieved with animal testing.
Beyond aiding in the development of more effective drug treatments, the new 3D printed tissue will also aid researchers in understanding brain disorders (such as schizophrenia), as well as degenerative diseases of the brain such as dementia. The first step in this will be understanding the human brain’s complicated neural networks better.
The director of ACES and author on the research project, Professor Gordon Wallace, said, "We are still a long way from printing a brain but the ability to arrange cells so as they form neuronal networks is a significant step forward.”
How It All Works
Researchers were able to create the neural cell structure in six-layers by creating a novel bio-ink with carbohydrate materials. The naturally occurring materials manage to not only facilitate accurate cell dispersion within the layers, but also protect the cells.
On top of it all, the 3D printing optimized bio-ink can be used in a standard cell culturing facility, eliminating the need for expensive equipment to bio-print the structure. The layered neural tissue is structured like human brain tissue—with all component cells located in the appropriate place within their layer.
For Wallace and his colleagues at the ARC Centre of Excellence for Electromaterials Sciences, the successful development of neural tissue is only the first step in developing high-quality replicas of organ structures to aid biomedical and pharmaceutical research.
"This study highlights the importance of integrating advances in 3D printing, with those in materials science, to realise a biological outcome," Professor Wallace said.
"This paves the way for the use of more sophisticated printers to create structures with much finer resolution.”
Photo Credits: 3DPrint.com
The 3D printing technology has seen a lot of innovations in the additive manufacturing industry as well as aerospace technology. Recently, the medical industry has taken advantage of 3D printing in creating medical implants.
In fact, scientists from Germany’s Laser Zentrum Hannover were able to develop a laser melting process to create implants made from nickel-titanium, platinum or stainless steel. The new technology developed was called selective laser micro-melting process. The project was carried out with the Institute of Biomedical Technology that uses selective laser micro-melting to coat electrodes for pacemakers with platinum.
The application of this new technology is to lengthen the lifespan of pacemakers. Researchers noted that one way of lengthening the life of the pacemaker is to adapt the form as well as surface of the electrodes. Platinum has inert properties as well as good conductivity. However, it is difficult to embed them on small medical devices using traditional casting methods without destroying the integrity of the medical implant. Thus, scientists developed the new procedure to effectively coat the pacemakers with the metal alloy.
Aside from effectively coating the medical implants with platinum, researchers were also able to create lattice structures from shape memory alloys that has the capability to retain the characteristics of the memory alloy. Scientists were also able to produce closed cell design stent structures from this new procedure using stainless steel.
It is clear that using lasers are very beneficial in additive manufacturing and in the medical industry to create next-generation implants that has better quality and will also last longer than conventional implants.
Whether 3D printed or not, bone replacements have always posed several problems for patients. For one, if the patient is a child, they will quickly grow out of whatever artificial implant they may receive. And even if the patient is an adult, they still need a bone replacement that will adapt to changes in their bodies as they age, just like a real piece of the human body. Luckily for everyone, researchers at several organizations are investigating new ways to create the perfect bone replacements—using 3D printing.
Versatile Bone Transplants
Chinese company Xi’an Particle Cloud Advanced Materials Technology Co., Ltd. announced in March that it been able to transplant a biodegradable 3D-printed bone into a rabbit. Using a unique process called Filament Free Printing, the company overcame many of the common issues of FDM 3D printing, such as expense and wastefulness.
The new precise method uses polymers, ceramics and UV light to create a more volatile ink. This ink can create artificial bones with the same pore structures, strength and versatility of real bones. The rabbit in question, who received a 3D-printed femoral condyle bone, started to grow new cells of its own on the artificial implant. The company plans to begin human trials of the new bone with their PCPrinter BCTM 3D printer this June.
The potential benefits of such as versatile bone implant are numerous: it could help patients who have suffered bone loss from cancer or other degenerative diseases. The technology is also much less costly, as current methods take bone grafts from the patient’s body or from cadavers.
Stem Cells for Precise Replacements
Another promising method of 3D printed bone replacements takes a completely different approach. Researchers hope an ultra-personalized bone replacement could be possible by printing 3D tissue using stem cells from the patient in question. Doctors could take a picture of the bone that needs replacement, input the data into the computer, and print a replacement that fits the defective bone precisely.
Kevin Shakeshaff, a University of Nottingham pharmacist, said, “The tissues of our body are structured at the level of single cells. Using 3D printing, we can position cells in precise places.”
The 3D bioprinter would create a scaffold for the bone, then cover it with adult human stem cells. The cells can then become many different types of bodily tissues. After the bone is implanted into the body, the scaffold will slowly degrade and be replaced by authentic bone within three months.
"The first advantage is you get something in the exact shape of the defect you're trying to replace," Shakeshaff said. "More subtly, you have the ability to organize where the cells go within the scaffold," he said.
Using a polylactic acid polymer and alginate gel substance, doctors are able to create a strong bone with cushioning for the cells. Patients will also benefit from better blood vessel formation than other methods.
The most exciting part about bone replacement research is that there are a wide variety of disparate methods being developed in tandem. This versatility of options will not only benefit patients with unique needs, but will help researchers further develop the best possible methods using 3D printing.
Photo Credits: Business Insider Fox News
The human brain is the most complex thing in the human body. Because it is the most important part of the body, it is protected by a thin layer called dura mater. The dura mater is divided into two complex layers. When surgeons need to conduct brain surgery, they need to cut through the protective layers as well as replace them after surgery; otherwise it will put the health of the patient at risk.
The problem is that the dura mater is very difficult to replace. However, researchers from the Maipu Regenerative Medical Technology developed artificial dura mater products with the help of a 3D bioprinter. Chief Officer Professor Xu Tao described the process dubbed as ReDura replaces the native dura mater of patients who underwent brain surgery.
This technology provides a structure which the tissues can grow. The 3D bioprinted scaffold is printed in a printer with two print heads. One print head is filled with human cells called bio ink while the other print head contains a printable water-based gel which serves as the biological paper. The biological paper supports the growth of the meningeal cell.
When the meningeal cells are printed, the machine sprays the bio ink to the biological paper. During the surgery, the scaffold is then inserted on the affected area. Eventually, it stimulates the collagen structures in the body to form layers which replaces the bioprinted dura mater that was once there. In a few months, the ReDura dissolves slowly into water and carbon dioxide leaving behind healthy tissue replacement that functions just like the original dura mater.
A new 3D Printed Anatomy Series developed by scientists at Monash University may be the most realistic alternative to practicing on cadavers for medical students yet.
An Effective and Streamlined Training Tool
The kit contains anatomical body parts specifically designed for medical education, with the potential to revolutionize training in places where cadaver-use is not possible. It includes all major parts of the body, including the limbs, torso, head and neck, but no actual human tissue. The kit is believed to be the first of its kind to become commercially available.
According to Professor Paul McMenamin, the Director of Monash University’s Centre for Human Anatomy Education, the anatomy series is cost-effective and carries the potential to drastically improve training and knowledge for doctors and other health professionals. It could also aid in the development of novel surgical strategies.
“For centuries cadavers bequested to medical schools have been used to teach students about human anatomy, a practice that continues today. However many medical schools report either a shortage of cadavers, or find their handling and storage too expensive as a result of strict regulations governing where cadavers can be dissected,” he said.
“Without the ability to look inside the body and see the muscles, tendons, ligaments, and blood vessels, it’s incredibly hard for students to understand human anatomy. We believe our version, which looks just like the real thing, will make a huge difference.”
A Worthy Alternative to Cadaver Use
Cadaver use for medical training has long been an issue in many countries where it is considered inappropriate for religious or cultural reasons. In these areas, the anatomy kit will be particularly useful.
“Even when cadavers are available, they’re often in short supply, are expensive and they can smell a bit unpleasant because of the embalming process. As a result some people don’t feel that comfortable working with them,” Professor McMenamin said.
The plastic models are also not subject to issues with preservation and regulation like actual cadavers.
3D Printing Accurate Models
The body parts are made by scanning real anatomical models with a CT or surface laser scanner. They are then printed using plastic or a plaster-like powder, creating high resolution specimens with accurate dimensions and color.
“Radiographic imaging, such as CT, is a really sophisticated means of capturing information in very thin layers, almost like the pages of a book. By taking this data and making a 3D rendered model we can then colour that model and convert that to a file format that the 3D printer uses to recreate, layer by layer, a three-dimensional body part to scale,” said McMenamin.
“Our 3D printed series can be produced quickly and easily, and unlike cadavers they won’t deteriorate – so they are a cost-effective option too.”
The developers are currently negotiating with commercial partners and hope to have the kit on the market this year. A scientific article related to the training tool was also published in Anatomical Sciences Education.
Photo Credits: 3DPrint.com
Creating a natural bone with 3D printing is challenging. The problem with creating bioprinted bones is that the materials needed to create them have yet to be developed. Researchers from the Southern Medical University in Guangdong China developed pure bone structures using 3D bioprinting.
Led by Professor Huang Wenhua, the researchers were able to create the bioprinted bones using bone powder and bio-glue. Unlike most bone implants that are made from titanium powder, the researchers were the first to develop the structures using pure bone material. The bone powder is allogeneic which means that it will be made from the same biological species thus making it more compatible for humans.
The benefit of this new technique is that unlike 3D printed titanium implants, the 3D printed pure bone structure will not be rejected by the body; thus it will help patients have faster recovery with fewer risks involved.
To test the new technique, the researchers are still testing different ways to create a natural replica of the human bone. So far, the team was able to successfully print rabbit and goat bones but it will be soon when they will be able to create human bones to suffice the need for bone implants in the country.
While the research still has a long way to go, the researchers are very optimistic that they will be able to use the new 3D printed bones in real medical cases in the following years. For now, they are contented in testing the new materials in the laboratory.
3D printing, which is synonymous with additive manufacturing in the industrial sector, is now quite popularly used as part of the mainstream treatment in surgery. In fact 3D printing is now seen as a potentially crucial procedure to surgically treat unborn babies with abnormalities.
Researchers from the Colorado Fetal Care Center has been studying on how to use 3D printing to perform surgery to correct fetal defects. Traditionally, surgical procedures involving unborn babies present not only risk to babies but also to the mothers.
Dr. Kenneth W. Liechty, a maternal fetal surgery specialist, noted that 3D printing will be very helpful in the pre-operative and intra-operative planning as well, as it will aid the patients to have faster healing process. The team of researchers conducted the first ever fetal surgery using 3D printing in April 2015.
The surgery involved an unborn baby who is suffering from myelomeningocele which is a common type of spinal bifida. Patients affected by this disorder will not be able to walk or will suffer from incontinence. It may also lead to other complications like hydrocephalus or the swelling of the brain. The researchers used a 3D printed replica of the fetus’ spine to assist the procedure.
The procedure was very sensitive but the doctors were able to successfully correct the condition of the unborn baby. With this recent development in 3D printing, it goes to show that 3D printing is not only used in additive manufacturing but it can also be used to save the lives of many, including unborn children.
Han Han was born with a rare disorder called congenital hydrocephalus, which caused her head to grow four times larger than was normal. At three years old, she wasn’t expected to live much longer unless something was done about the condition. Doctors in China, her home country, came to the rescue by developing a titanium mesh skull with the help of a 3D printer. Surgeons at the Second People’s Hospital of Hunan Province were successfully able to remove most of Han Han’s skull and replace it with the titanium one. Now, Han Han is expected to make a full recovery, with a new lease on life.
Han Han was first diagnosed with hydrocephalus at 6 months. The disease usually develops in the womb or at birth, causing an excess of fluid to fill the brain. By the time her father was able to arrange her surgery, Han Han’s brain weighed about 20 kg, while her overall body weight was 32 kg. She was no longer able to lift her head from her pillow, and doctors gave her about two months to live if nothing was done.
According to Dr. Bo of the Second People’s Hospital, “CT results showed that Han Han’s brain was filled 80 percent with water. If she was not sent to hospital for treatment, Han Han would not have survived the summer. We had to first eliminate the infection in Han Han’s head because the brain wound area was too large, and we needed to do skin graft surgery and insert a shunt to help eliminate the infection, and remove the fluid from her brain.”
At first, the surgery may not have been a possibility, if it wasn’t for the efforts of Chen Youzhi, Han Han’s father, in collecting donations for the procedure. Despite the use relatively inexpensive 3D printing technology to create the skull prosthetic, the surgery was incredibly expensive. Han Han’s mother left the family when she was only one year old, but that didn’t hinder Youzhi’s efforts. A combination of funding from family and friends and online donations helped Youzhi collect a portion of the money needed for the surgery, which cost between $64,000-$80,000 USD.
The surgeons were able to create a model of Han Han’s skull using 3D printing technology and a CT scanner. They created three titanium implants that would work together to replace the top of her skull. In a seventeen-hour surgery, doctors had to first drain away the fluid from her brain, and then insert saline pads to cushion her new titanium skull.
While the surgery is seen as the first complete skull replacement in the world, it is one among many successful partial skull and face reconstructions made possible with 3D printing. American baby Gabriel was born with unilateral coronal synostosis, which caused his growth plates to fuse prematurely. Doctors were able to create 3D models of his skull to help them practice a delicate procedure to cut and reshape his bones to correct the problem. Gabriel emerged from a successful reconstruction surgery just last year.
These surgeries are only two of the many examples of how young children are able to benefit from advanced procedures that would otherwise be too risky for them to attempt, with the help of 3D printing.
Photo Credits: Medical Daily and Fox News
UPDATED TUTORIAL: A Ridiculously Easily Way to Convert CT Scans to 3D Printable Bone STL Models for Free in Minutes
Hello, it's Dr. Mike here again with another tutorial and video on medical 3D printing. In this tutorial we're going to learn how to take a DICOM-based medical imaging scan, such as a CT scan, and convert into an STL file in preparation for 3D printing. We will use the free, open-source software program Osirix to do this. Once the file is converted into STL format, we will use the free software packages Blender and Meshmixer to prepare the file for 3D bioprinting. If mastered, this material should easily allow you to make a high-quality 3D printed medical model in less than 30 minutes using free software. Expensive, proprietary software is not needed. This tutorial is designed primarily for Macintosh users since Osirix is a Macintosh-only program. If you use Windows or Linux, please stay tuned for my upcoming tutorial on using free, open-source 3D Slicer to create medical and anatomic models. If you haven't already done so, please see my tutorial on selecting the best medical scan to create a 3D printed model. If you start your 3D printed model project with the wrong kind of scan, your model will not turn out well. Selecting the right kind of scan is critically important and will save you a lot of frustration. Take a few minutes to look over this brief tutorial. It will be well worth your time.
Before you start, DOWNLOAD THE FILE PACK that accompanies this video so you can follow along on your own computer. When you finish the tutorial, you will have your very own 3D printable skull STL file. Download is free for members, and registration for membership is also free and only takes a minute.
Video 1: The video version of this tutorial. It takes you from start to finish in 30 minutes. The written version here has more detail though. A Few Brief Definitions
What is Osirix?
Osirix is a Macintosh-only software package for reading medical imaging scans (Figure 1). There are several versions. There is an FDA-approved version designed for doctors reading scans in clinics and hospitals, a 64-bit version for research and other nonclinical activities, and a free, 32-bit version. The main difference between the free 32-bit version and the paid 64-bit version is the 64-bit version can open very large imaging studies, such as MRI exams with thousands of images. The 32-bit version is limited to about 500 images. Additionally, there is a performance boost with the paid versions. If you are just getting into 3D bioprinting, the free, 32-bit version is a great place to start. It can be downloaded at the Osirix website here.
Figure 1: An example of Osirix being used to read a CT scan.
What is DICOM?
DICOM stands for Digital Imaging and Communications in Medicine. It is the standard file format for most medical imaging scans, such as Computed Tomography (CT), Magnetic Residence Imaging (MRI), ultrasound, and x-ray imaging studies.
What is STL?
STL, or STereoLithography format , is an engineering file format created by 3D Systems for use with Computer Aided Design software (CAD). The file format is primarily used in engineering, and has become the standard file format for 3D printing.
The Problem with 3D Printing Anatomic Structures
The major problem with trying to 3D print anatomic structures from medical scans is that the medical scan data is in DICOM format and 3D printers require files in STL format. The two formats are incompatible. There are very expensive, proprietary software packages that can perform the conversion between DICOM and STL. A little-known secret is that this can also be done using free, open-source software. Osirix is the best solution for Macintosh. 3D Slicer is the best solution for Windows and Linux. I will discuss 3D Slicer in an upcoming tutorial.
If you haven't already, please download the DICOM data set we will be using in this tutorial. This data set is from a high quality CT scan of the brain and skull. It has been anonymized and has been put in the public domain for research by the US National Cancer Institute. Also included with the download packet are other files we will use for this tutorial, including the final STL file of the skull. The download is free for members, and registration for membership is also free and only takes a minute.
From the Macintosh Finder navigate to the folder with the downloaded tutorial file pack and double-click on the file TCGA-06-5410 sharp.zip.
Opening the CT scan with Osirix
Open Osirix. From the File menu, click Import, Import Files. Click Open. (Figure 2)
Figure 2: Importing the CT scan into Osirix
Navigate to the folder that contains your DICOM data set. Click the Open button.
Osirix will ask you if you want to copy the DICOM files into the Osirix database, or only copy the links to these files. Click "Copy Files."
Osirix will begin to copy the files into the database. A progress bar will be shown on the lower left-hand corner. When the data is imported you'll see a small orange circle with a "+" in it. This orange circle will eventually go away when Osirix is finished analyzing the study, but you can open the study and work with it while Osirix does some cleanup postprocessing. Left click on the study.
You will see an icon with a label "FIDUCIALS 1.0 SPO cor, 216 Images." This is a CT scan of the head with coronal slices at 1 mm intervals. Double-click on this icon, Figure 3.
Figure 3: The study when opened
Osirix will remind you that you're not supposed to be using it for diagnostic scan reading on real patients unless you are using the more expensive FDA approved version, Osirix MD we're just using it to create a 3D model, so click "I agree."
At this point, the study will load. Use the mouse wheel or the bar on the top of the screen to scroll.
You can see that this is a pretty decent CT scan of the head for 3D printing. There is not much artifact from metallic dental implants because the maxilla and mandible have been cut off.
Segmenting the bony skull and creating a new series
We can measure the density of the bony structures using the Region Of Interest or ROI tool. This measures the Hounsfield density, or CT density, of the target area. Select the oval tool from the drop-down menu, Figure 4.
Figure 4: The ROI tool.
Choose a region of bone using the oval tool. You will see that information about this region is displayed. What we are interested in is the mean density, which in this case is 1753.194, Figure 5.
Figure 5: Density measurement using ROI tool. The mean density is 1753.194, as shown in maroon field.
Use the ROI tool to select another region in the brain. You will see that the mean attenuation, or density, is much less, in this case 1059.137, Figure 6.
Figure 6: Density measurement of the brain tissue.
Finally, use the oval tool to choose an area in the air adjacent to the head. You can see that the mean attenuation of this region is 38.514, Figure 7.
Figure 7: Density measurement of air.
In this scan the Hounsfield attenuation numbers have been shifted. In a typical scan, air measures about -1000, soft tissue between 30 and 70, and bone typically greater than 300. In this scan those numbers have been increased by 1000. Since we were thorough enough to check the Hounsfield attenuation before moving on, we can easily correct for this shift.
Under ROI menu select Grow Region 2D/3D Segmentation, Figure 8.
Figure 8: The Grow Region tool
In the Segmentation Parameters window that pops up, set the following: Lower Threshold 1150 Upper Threshold 3000. Generate a new series with: Inside pixels 1000 Outside pixels 0
Be sure to check the checkbox next to the Set Inside Pixels, and Set Outside Pixels fields, Figure 9.
Figure 9: Setting up the Segmentation Parameters window.
Next, make sure you select a starting point for the algorithm. Left click on one of the skull bones. Green crosshairs will show. All of the bone that is contiguous with point you clicked will now be highlighted in green, Figure 10.
Figure 10: Setting the starting point for segmentation. The target region turns green.
Click the Compute button
Osirix will generate a new series with the bones being a single white color with a value of 1000, and everything else being a black color with a value of zero, Figure 11. Creating a separate series just for 3D printing purposes is the secret to getting good 3D models from Osirix. Trying to generate a 3D surface model directly from the 3D Surface Rendering function underneath the 3D Viewer menu is tempting to use, however it will not work well for generating STL files. This is not obvious, and the source of much frustration for beginners trying to use Osirix for 3D printing.
Figure 11: The new bitmapped series shown on right of screen. This series has only two colors, black and white. It is idea for conversion to and STL surface model.
Generating an STL file from the new bitmapped series
Now we are ready to create our 3D surface model. Make sure that your new bitmapped series is highlighted. Click on the 3D viewer menu and select 3D Surface Rendering, Figure 12. Leave the settings set to their default values. Click OK as shown in Figure 13.
Figure 12: Selecting 3D Surface Rendering
Figure 13: Setting 3D surface rendering settings
Osirix will then think for a few moments as it prepares the surface. You can see that a relatively good approximation of the skull has been generated. Use of the left mouse button to rotate the 3D model.
Next were going to export the 3D surface model to an STL file. Click Export 3D-SR and choose Export as STL as show in Figure 14. Type the file name "skull file." Click Save.
Figure 14: Exporting model to STL file format.
Cleaning up the 3D model in Blender
You can see from the 3D rendering that there are many small islands of material that have been included with the STL file. Also, the skull has a very pixelated appearance. It does not have the smooth surface that would be expected on a real skull. In order to fix these problems, we're going to do a little postprocessing in Blender, a free open-source 3D software program.
If you don't already have Blender on your computer, you can download it free from blender.org. Blender is available for Windows, Macintosh, and Linux. Select your operating system, preferred installation method, and download mirror.
Once Blender is installed on your computer, open it. In the default scene there will be a cube. We don't need this. Right click on the cube to select it. Then delete it using the delete key on a full keyboard or the X key on a laptop keyboard. Blender will ask you to confirm you want to delete the object. Click Delete as shown in Figure 15.
Figure 15: Deleting the default cube.
Next, we are going to import the skull STL file. From the File menu select Import, STL, as shown in Figure 16. Navigate to the skull STL file you saved from Osirix, and double-click it. Blender will think for a few seconds and then return to what appears to be an empty scene, as shown in Figure 17. Where is your skull? To find your skull, use the mouse scroll wheel to zoom out. If you zoom out far enough you will see the skull. The skull appears to be gigantic, as shown in Figure 18. This is because the default unit of measurement in the skull is 1 mm. In Blender, an arbitrary unit of measurement called a "blender unit" is used. When the skull was imported, 1 mm of real size was translated into 1 blender unit. Thus the skull appears to be hundreds of blender units large, and appears very big.
Figure 16: Importing the STL file into Blender
Figure 17: The "empty" scene. Where is the skull?
Figure 18: Zoom out and the skull appears!
The skull is also offset from the origin. We are going to correct that. Make sure that the skull is still selected by right clicking on it. If it is selected it will have a orange halo. In the lower left corner of the window click on the Object menu. Select Transform, Geometry to Origin as shown in Figure 19. The skull is now centered on the middle of the scene.
Figure 19: Centering the skull in the scene.
Deleting Unwanted Mesh Islands
First, let's get rid of the extra mesh islands. There is a menu in the lower left-hand corner of the window that says Object Mode. Click on this and go to Edit Mode, as shown in Figure 20.
Figure 20: Entering Edit mode in Blender.
Now we are in Edit Mode. In this mode we can edit individual edges and vertices of the model. Right now the entire model is selected because everything is orange. In edit mode you can select vertices, edges, or faces. This is controlled by the small panel of buttons on the bottom toolbar. Make sure that the leftmost or vertex selection mode is highlighted and then right click on a single vertex on the model, as shown in Figure 21. That vertex should become orange and everything else should become gray, because only that single vertex is now selected, Figure 22.
Figure 21: Vertex selection mode
Figure 22: Select a single vertex by right clicking on it.
Under the Select menu, click Linked, as shown in Figure 23. Alternatively, you can hit Control-L. This selects every vertex that is connected to the initial vertex you selected. All the parts of the model that are contiguous with that first selection are now highlighted in orange. You can see that the many mesh islands we wish to get rid of are not selected.
Figure 23: Selecting all linked vertices. We are next going to invert the selection. Do this by again clicking on the Select menu and choosing Inverse, Figure 24. Alternatively, you can hit Control-I. Now, instead of the skull being selected, all of the unwanted mesh islands are selected, as shown in Figure 25. Now we can delete them. Hit the delete key, or alternatively the X key. Blender asks you what you want to delete. Click Vertices, Figure 26. Now all of those unwanted mesh islands have been deleted.
Figure 24: Inverting the selection.
Figure 25: The result after inverting the selection. Only the unwanted mesh islands are selected!
Figure 26: Deleting the unwanted mesh islands.
Repairing Open Mesh Holes
We can see that on the top of the skull there is a large hole where the skull was cut off by the scanner. Because the bone surface was cut off, Osirix left a gaping defect, Figure 27. Before 3D printing, this will have to be corrected. This is what is called a manifold mesh defect. It is an area where the surface of the model is not intact. A 3D printer will not know what to do with this, such as whether it should be filled in or left hollow. Fortunately, it is relatively easy to correct.
Figure 27: A large open mesh hole at the top of the skull.
Using the Select menu in the lower left-hand corner, click on Non-Manifold. This will select all of the non-manifold mesh defects in your model. You can see that the edge of our large hole at the top of the skull has been selected and turned orange. This confirms that this defect has to be fixed.
Unselect by hitting the A key. Then, go to Edge select mode by clicking on the Edge Select button along the lower toolbar. Holding down the Alt key, right-click on one of the edges of the target defect, in this case the top of the skull. That familiar orange ring has formed. Your selection should look like Figure 28. Let's fill in this hole by creating a new face. Hit the F key. This creates a new face to close this hole, Figure 29.
Figure 28: The edge of the hole is selected, as indicated by the orange color.
Figure 29: The hole when filled with a new face.
Due to the innumerable polygons along the edges, the face is actually quite a complex polygon itself. Let's convert it to a simpler geometry. With the face still selected hit Control T. You can alternatively go to the Mesh menu and select Faces, Triangulate Faces as shown in Figure 30. This will convert the complicated face into simpler triangles. As you can see, some of these triangles are quite large relative to the other triangles along the skull surface. These large triangles may become apparent when smoothing algorithms are applied or 3D printing is performed. Let's reduce their size. Hit the W key and then select Subdivide Smooth, as shown in Figure 31. The triangles are now subdivided. Let's repeat that operation again so that they are even smaller. Hit the W key and again select Subdivide Smooth.
Figure 30: Converting all faces into triangles.
] Figure 31: Subdividing and smoothing the selected faces.
Smoothing the Model Surface
Next let's get rid of that pixelated appearance of the model surface. First, we need to convert all of the polygons in the model to triangles. The smoothing algorithms just work better with triangles. Staying in Edit mode, hit the A key. The A key toggles between selecting all and unselecting all. If you need to, hit the A key a second time until the entire model is orange, thus indicating that it is selected. Hit Control-T, or alternatively use the Mesh menu, Faces, Trangulate Faces. This will convert any remaining complex polygons to triangles.
Go back to Object mode by hitting the tab button or selecting Object Mode from the bottom toolbar. We are now going to apply a smoothing function, called a modifier, to the skull. Along the right of the screen you'll see a series of icons, one of which is a wrench, as shown in Figure 32. Click on that. This brings up the modifier panel, a series of tools that Blender uses to manipulate digital objects. Click on the Add Modifier button and select the Smooth modifier. Do not select the Laplacian Smooth modifier. That is different. We just want the regular Smooth modifier, as shown in Figure 33. Leaving the Factor value at 0.5, increase the Repeat factor until you are satisfied with the surface appearance of your model. For me, a factor of 20 seemed to work, Figure 34. At this point the modifier is only temporary, and has not been applied to the model. Click on the Apply button. Now the smoothing function has been applied to the model.
Figure 32: The Modifiers toolbar on the right.
Figure 33: The Smooth modifier
Figure 34: Setting the Smooth modifier to repeat 20 times.
Rotating and Adjusting the Model Orientation
When the model was originally exported from Osirix and opened in Blender, it was at a strange orientation. We can correct to this easily. Click on the View menu from the left portion of the lower now bar and select Front. This orients the model from the frontal view, and you can see that in this orientation we are looking at the top of the skull. To correct this, we will rotate the model along the X axis. First, make sure that the cursor is inside the model window. Then, Hit the R key and then the X key, and type "180." This will rotate the model on the X axis by 180°. Hit the return key to confirm the modification. Don't worry if the skull isn't facing the correct way right now, we will fix that later.
Now we are ready to export our cleaned up skull model. Go to the File menu, click Export, STL. Navigate to your desired folder and save your STL file. Since I corrected several defects in this mesh file, I called the file "skull file corrected.stl"
Performing a Final Inspection Using Meshmixer
If you haven't already done so, go to the Autodesk Meshmixer website at http://www.meshmixer.com/download.html and download and install Meshmixer. The software is free. Once installed open the program and select Import. Navigate to your STL file and double-click it. Meshmixer has a variety of nice features, and one of them is a mesh correction function. Once your file is open click on the Analysis button along the left nav bar. Click on Inspector as shown in Figure 35. Meshmixer will now analyze the STL file for obvious mesh defects. Anything that is detected will be highlighted by red, pink, or blue lines. You can see that our skull model appears to be defect free. Click on the done button and quit Meshmixer.
Figure 35: Running the inspector tool in MeshMixer Your STL file of the skull is now ready for 3D printing!
In this tutorial you have learned how to take a DICOM data set from a CT scan and use it to create a 3D printable STL file using free software. First we used the Osirix to segment a CT scan and convert it to an STL file. Then we performed cleanup operations on the STL file using the Blender and Meshmixer, both free programs. For additional information on how to select an appropriate CT or MRI scan for 3D printing please see my previous tutorial. If you want to learn more about using Blender to fix more extensive defects in bone models, you can view to other tutorials I have created:
3D Printing of Bones from CT Scans: A Tutorial on Quickly Correcting Extensive Mesh Errors using Blender and MeshMixer
Preparing CT Scans for 3D Printing. Cleaning and Repairing STL Files from Bones using Blender, an advanced tutorial
A variety of useful tutorials for 3D printing is available on the Tutorials page. If you are planning on attending the 2015 Radiological Society of North America (RSNA) meeting in Chicago this November, look for my hands-on course "3D Printing and 3D Modeling with Free and Open-Source Software." I will give more tips and tricks for creating great 3D printed medical models using freeware.
I hope you find this tutorial helpful in creating your own medical and anatomic models for 3D printing. Please stay tuned for my next tutorial on using the free, open-source program 3D Slicer to create medical 3D models on Windows and Linux platforms.
If you are creating your own 3D printed medical models, please share your models with the Embodi3D community in the File Vault. If you have questions or comments, please leave a comment below or start a discussion thread in the Forums.
Sample free downloads
A Collection of Free Downloadable STL Skulls for you to 3D print yourself.
3D printable human heart in stackable slices, shows amazing internal anatomy.
A Collection of Spine STL files to download and 3D print.
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The use of 3D printing in medicine has taken the world by storm. Many countries like China, US and in Europe are now using 3D printing technology to treat patients suffering from different orthopedic disorders.
Recently, FDA approved the innovation of Joimax ®. This German company has developed minimally invasive methods for endoscopic spinal surgeries. The product that was approved is Endoscopic Lumbar Interbody Fusion (EndoLIF® On-Cage implant). The implants are printed using titanium and by the method called Electron Beam Melting. The final product features porous surface that comes with a diamond cell structure that allows the cells to proliferate as well as bones to grow on the metal. The company used the titanium alloy because it is well-known for its great biocompatibility with human tissues and it also has a good affinity with bones. This innovation has osteointegrative abilities.
Two German surgeons Dr. Ralf Wagner and Dr. Bernd llerhaus have used the EndoLIF implants to treat 200 patients and the success rate of the implants were very high. The advantage of this type of FDA-approved product is that it is durable and gentle on the nerves. It also preserves the bony structures thus avoiding scar tissues from developing that can cause possible risks of injuries in the future.
The innovations in 3D printing technology in the medical field are very promising and can help a lot of patients suffering from orthopedic anomalies. It will be soon that this product will be available for medical practitioners all over the world.
Hello, it's Dr. Mike here again with another tutorial on medical 3D printing. In this tutorial we are going to learn what types of medical imaging scans can be used for 3D printing. We will also explore the characteristics those scans must have to ensure a high quality 3D print. This is one of a series of 3D printing tutorials that will teach you how to create 3D printed anatomical and medical models yourself. Open source and commercial software are covered in the tutorials along with 3D printer selection and setup. This tutorial is followed by a tutorial on Creating 3D Printable Medical Models in 30 minutes using free software: Osirix, Blender, and MeshMixer.
Introduction to Selecting a Medical Scan for 3D Printing
If you listen to the hype in the press, it sounds like any medical imaging scan can be easily converted into a high quality 3D printed anatomic model, and any structure of interest can be shown clearly and beautifully. This is simply not true. In fact, most conventional medical imaging scans are not suitable for 3D printing. Those few that are suitable will probably only produce high-quality 3D prints of a few anatomic structures. In this tutorial I will go over the basic elements that make a medical scan suitable for 3D printing. I will briefly discuss different imaging modalities such as CT, MRI, and ultrasound. By the end of this tutorial you should be able to recognize whether a medical scan is suitable for 3D printing. If you are planning on having a medical scan done with the intention of 3D printing from the scan, you will be able to protocol the scan appropriately to enable a high quality 3D print.
I'd first like to take a moment to discuss the standard imaging planes used in medical scans. When a medical scan is performed, images of the body are usually captured and displayed in one of three standard imaging planes. These are the transverse plane (also called axial plane), the coronal plane, and the sagittal plane. Figure 1 demonstrates these planes. In layman's terms, the axial plane divides the body into top and bottom, the coronal plane front and back, and the sagittal plane right and left. CT and MRI scans are typically comprised of several series of images. Each series is comprised of a stack of images in the same plane spaced out evenly. When a medical scan is converted into a format suitable for 3D printing, such as an STL file, the computer takes this stack of images and extrapolates the volume of an object. A surface is then calculated around that volume. That surface is what becomes the 3D printed model.
Figure 1: Standard imaging planes used in medical scans. Source: National Cancer Institute
Imaging Modality: CT versus MRI versus ultrasound
In order to understand what scans are best used for 3D printing, a very basic understanding of the types, or modalities, of medical scans is needed. The medical physics behind how these scans work can literally fill volumes. Radiology residents are required to take board examinations on the physics and engineering of medical scanners as part of their training. I will attempt to summarize only the most critical information about medical scans into a few short paragraphs to get you up and 3D printing as quickly as possible.
Computed Tomography, or CT scans, are created when an x-ray beam is rotated around the patient. An x-ray detector on the opposite side of the emitter records the strength of the beam that emerges from the other side of the patient. Knowing the angle and position of the x-ray emitter and the strength of the beam emerging from the other side of the patient, a computer can calculate the x-ray appearance of the body in three dimensions. An x-ray beam is generally absorbed or deflected by electrons in matter. Since the density of electrons in matter is more or less the same as the actual physical density of matter, a CT scan can be considered to be a density map of the patient. Things that are dense, such as bone or metal, will appear white. Things that are not dense, such as air, appear black. Figure 2 shows how the different densities of tissue appear on a standard CT scan. When intravenous contrast is given, which contains an iodine-containing chemical that is very dense, it appears white. Fat is not very dense and floats on water, thus it has a blackish appearance.
What else floats on water? Choices: bread, apples, very small rocks, cider, gravy, cherries, mud, churches, lead, a duck. (This is a joke. If you get the reference, please leave a comment and give yourself a star).
Figure 2: Effect of tissue density on CT scan appearance. This CT scan image of the head at the eyes shows fat in the temporal fossa as black (red arrow), intermediate density brain tissue as gray (green arrow) and dense calcium-laden bone in the skull as white (blue arrow).
Magnetic Residence Imaging, or MRI, is a type of imaging that uses very strong magnetic fields to generate an image. The hydrogen atoms that are part of almost all biological structures (water, fat, muscle, protein, etc.) align with the magnetic field. Radio waves can be sent into the scanner causing the hydrogen atoms to flip orientation. When the radio waves are turned off, the hydrogen atoms flip back and emit their own faint radio signal. Based on analysis of these faint radio emissions and by varying the magnetic field strength and timing of the radio wave pulses, a variety of images can be generated. These different pulse sequences can be used to highlight different types of tissue.
Take Figure 3 for example. Four different pulse sequences are shown of the same slice of brain: T1, T2, FLAIR, and T1 with gadolinium contrast. On the T1 image tissues with fat are a bright white, as shown by the fat in the skin (white arrow). The hard, calcium-filled tissue of the skull is black, with the exception of a small amount of bone marrow which is gray in color and sandwiched between the inner and outer skull plate (yellow arrow). The watery cerebral spinal fluid in the lateral ventricles are black (red arrow). However, on the T2 image the watery cerebral spinal fluid is bright white (red arrow). T2 images show water very well. In addition to the water in the ventricles, swelling of the brain tissue due to an adjacent brain tumor can be seen as a white appearance (blue arrow). FLAIR images are similar to T2 images except pure water has been subtracted from the image. Thus tissue swelling (blue arrow) is still clearly visible but the cerebral spinal fluid in the ventricle (red arrow) now appears black. Finally, in the T1 images with gadolinium IV contrast small blood vessels are visible. Additionally, you can actually see the brain tumor and meninges turning white from contrast enhancement (purple arrows).
Figure 3: MRI of the brain at the same level using four different pulse sequences. The patient has a left frontal lobe brain tumor.
When 3D printing from an MRI scan, it is important to select images from a pulse sequence that will highlight the structure you wish to visualize. Arteries, tumors, body fluid, bones, and general tissue are all best seen on different sequences. If you choose the wrong imaging sequence to generate your 3D model from, you will encounter only frustration.
Ultrasound images are generated when soundwaves are sent into the body by an ultrasound emitter. The waves then bounce off various structures and are detected by a receiver, typically built into the emitter. The concept is similar to sonar that is used on ships and submarines. Based on the strength and depth of the soundwave return, an image can be created. Ultrasound images can be used for 3D printing, however it is very difficult to do so because individual images are not registered in a fixed place in space. The images are acquired by sliding the ultrasound transducer on the skin. The exact location in space and angle of the transducer at the time of image acquisition is not known, which makes generation of a 3D volume difficult or impossible. In general, ultrasound is not recommended as a source of imaging data for 3D printing for the beginner.
Key features of medical imaging scans used in 3D printing
There are certain features common to all scan modalities that can help you to create a good 3D print. When considering making a 3D medical or anatomic model you must first decide what you want the model to show. Should it show bones, arteries, or organs? Having a model with unnecessary structures included not only makes it more difficult to manufacture, but it also diverts attention away from the important parts of the model. Give this careful thought. Once you have decided what you want to show, evaluate the medical scan you want to create your model from carefully. If the scan doesn't have the proper characteristics, you can exponentially increase the difficulty of getting a 3D printable model from it.
1. Presence of Intravenous contrast
Take a look at these two axial (transverse) images from CT scans of the upper abdomen (Figure 4). Both images show slices of the upper abdomen at the level of the tops of the kidneys and liver. What is the difference between the two? You'll notice that on the rightmost scan the aorta is white, whereas on the left scan the aorta is gray. Figure 5 is a zoomed image of this region and shows this in more detail. This is because the rightmost scan was performed with intravenous contrast and that contrast is causing the aorta and other vessels to turn a bright white color.
Figure 4: The effect of intravenous contrast.
Figure 5: Close-up view of the abdominal aorta with (right) and without (left) intravenous contrast.
Take a closer look at the kidneys. Figure 6 shows a zoomed-in image. The outer part of both kidneys on the contrast-enhanced scan on the right are a light shade of color. This is due to blood mixed with contrast going into the outer cortex of the kidney. With the contrast-enhanced scan you can clearly see the edge of the kidney, even where it touches the liver. On the noncontrast scan the border of the kidney is only discernible where it is adjacent to the darker colored fat. Where it touches the liver it is difficult to see where the kidney ends and the liver begins. If you want to make a print of the kidney, it will be very difficult to discern the edge of the kidney without IV contrast.
Figure 6: Close-up view of the right kidney with (right) and without (left) intravenous contrast.
If you are trying to create a 3D printed model of a bone, it is best to create it from a scan without IV contrast. This is because the bone is the only thing that will be a white color in the scan. This allows your software to easily separate the bones from other tissues. The presence of intravenous contrast may trick the software into thinking that blood vessels or organ tissue is actually bone, and it may improperly include these structures in the 3D printable surface model. These unwanted structures can be manually removed, but this can be an incredibly time-consuming and laborious exercise. It is best to avoid this problem in the first place.
On the other hand, if you are trying to 3D print a blood vessel, tumor, or organ, then intravenous contrast is absolutely necessary. Vessels and tumors will light up, or enhance, with IV contrast, turning white on a CT scan. Which will make separation of these structures from background tissue more easy to perform.
2. Timing of intravenous contrast
If you are creating a 3D printed model of a blood vessel, tumor, or organ, merely having intravenous contrast in your scan is not sufficient. You also must have the proper contrast timing. Contrast injected into a vein before a medical scan is not static. It is a very dynamic entity, and flows through the blood vessels and tissues of the body at different times before being excreted by the kidneys.
Intravenous contrast is injected through an IV catheter, typically in the arm immediately before initiation of scanning. The contrast flows with the blood into the superior vena cava, the large vein in the chest, and then into the heart where it is then pumped into the pulmonary arteries. It is at this point, typically about 15 to 20 seconds, that is the best time to perform a scan to clearly visualize the pulmonary arteries. The contrast-filled blood then flows out of the lungs back to the heart where it is pumped into the aorta and its branches. This may be about 30 seconds after contrast injection, and is the best time to see the arteries. The contrast-filled blood then percolates into the capillaries of the tissues throughout the body. This is the point of maximal tissue enhancement, and is usually the best time to see tumors and organs. The blood then leaves the tissues and drains back into the veins, which is the best time to look at the veins. Finally, after about five minutes or so, the contrast begins to be excreted by the kidneys into the urine, and can be seen within the collecting system of the kidneys, the ureters, and the bladder.
Take a look at Figure 7. When the scan was performed in the arterial phase (left) you can clearly see the aorta, arteries of the intestine, and outer rim (cortex) of the kidneys have turned white with contrast-enhanced blood (green arrows). After about five minutes the scan was repeated (right), and on these delayed phase images only a small amount of contrast is left within the aorta and blood vessels. However, contrast can be seen concentrated within the central portions of the kidney (red arrow). This is urine mixed with contrast collecting in the renal pelvis and ureter.
Figure 7: Transverse (axial) images from a contrast-enhanced CT scan from a patient with intravenous contrast in the arterial (left) phase and delayed urographic (right) phase.
The point I'm trying to make here is that merely having intravenous contrast is not good enough. When the scan was taken relative to the contrast injection, in other words the timing of the contrast, is critically important to visualizing the target structure.
3. Oral contrast
In addition to intravenous contrast it is very common for oral contrast to be given prior to CT scans of the abdomen or pelvis. This is that nasty stuff that you are asked to drink about two hours before your scan. Oral contrast is designed to stay within the intestines so they can be clearly seen and evaluated. Take a look at Figure 8. In this CT scan of the abdomen intravenous contrast has clearly been given as the right kidney is white and enhancing (red arrows). Oral contrast has also been given, as several loops of small intestine can be seen filled with a substance that appears white on the CT scan (green arrows).
Unless you are trying to 3D print the intestines, for the most part oral contrast is something you do not want in your source imaging scans. If you are trying to separate out bones, organs, or blood vessels for printing, the presence of oral contrast will increase the likelihood that intestines will be accidentally included in your 3D printable model.
Figure 8: The effects of oral contrast on a CT scan of the abdomen.
4. Slice thickness
Take a look at these two CT scans of the chest (Figure 9). What is the difference between them? Both of them have IV contrast and both of them are showing the heart. Obviously, the scan on the right is of higher quality than that on the left, but why? The reason has to do with the thickness of the image slices. When CT scans are performed they are reconstructed into slices in the axial (transverse) plane. The axial plane is the plane that is parallel to the ground if you are standing upright. When the axial slices are stacked on top of each other the data can be used to create images in a different plane, such as when viewed from the front (the coronal plane), as in these example images. The axial slices that were used to create the coronal image on the left were 5 mm thick, whereas the axial slices used to create the image on the right were only 1 mm thick. You can see that the thick slices in the leftmost image generate structures with a very coarse appearance. If you try to 3D print an anatomic model from a scan with thick slices, your model will have a similar rough appearance. It is very important to use scans with thin slices, preferably less than 1.25 mm in thickness, when creating a model for 3D printing.
Figure 9: The effect of slice thickness on three-dimensional reconstructions.
5. Imaging artifact
Finally, take a look at these two CT scans of the face (Figure 10). What is the difference between them? The scan on the left clearly shows the teeth of the upper jaw as well as the bones of the upper cervical spine. The scan on the right however has white and black lines crisscrossing the mouth and obscuring the teeth. This type of artifact, called a beam hardening artifact, was created by metallic fillings in the teeth. When the CT scan was performed, the x-ray beam could not penetrate the metal fillings in the teeth to reach the detector. Subsequently, the scanner has no information about the x-ray appearance of the tissues along that x-ray path. When it generates an image from the x-ray data, the x-ray path with the missing information is shown as a white or a black line. The same phenomenon can be seen with any metallic object within the body, such as an artificial hip or spine fixation rods. If the scan on the right were converted to an STL file for 3D printing, the white lines would be 3D printed as well and the print would look as if sharp spikes were coming out of the mouth. Metallic objects also cause imaging artifact in MRIs. Metal on MRIs typically looks like a big black blob that obscures everything around it.
Figure 10: Two CT scans through the face and jaw. What is the difference between the two?
6. Reconstruction kernel
Take a closer look at the two CT scans of the face (Figure 10). In particular, look closely at the muscle and fat tissue of the neck. The scan on the left shows the muscle and fat tissue as being somewhat noisy. It has a granular type of appearance. On the rightmost scan however, the muscle and fat tissues appear rather smooth. This is because the two scans use a different type of reconstruction kernel. Think of the reconstruction kernel as equivalent to a sharpening or blurring function in Photoshop. The sharper kernel on the left shows the edges of the bones very clearly at the expense of causing a speckled appearance of the muscles and fat. The softer kernel on the right shows the muscle and fat more accurately, at the expense of causing the bones to have a more indistinct edge. Sharp kernels are used to make it easier to find hairline fractures and other difficult to detect abnormalities in the bones. However, for 3D printing smoother reconstruction kernels are generally best. Reconstruction kernel is primarily a factor only in CT scans.
Figure 11: Zoomed image from Figure 10 of the angle of the jaw. Note how the sharp kernel has much more clearly defined bone edges, but also has a speckled, noisy appearance to the soft tissues. Final thoughts
So there you have it. In this tutorial we have gone over the main types of imaging modalities used for 3D printing (CT, and MRI), as well as six very important factors to consider with any type of imaging scan you are thinking about using for 3D printing. There is a saying when it comes to medical 3D printing: "garbage in, garbage out." No matter what your skill level or amount of available free time, if you start the 3D printing process with a problem-laden medical scan, you will encounter nothing but frustration and probably end up with a bad 3D model assuming you can make the model at all. Do yourself a favor and carefully evaluate your medical scan prior to sinking the time and energy into creating a 3D model from it.
I hope you enjoyed this tutorial and found it helpful. If you liked this article please look see my next to tutorial on Creating a 3D Printable Medical Model in 30 Minutes Using Free Software: Osirix, Blender, and MeshMixer. Additionally, you may wish to check out the Tutorials section of the website.
Also consider registering as a member. Registration is free and allows you to post questions and comments both for blog articles and in the discussion forums. Additionally, you can download free 3D printable models from the file library.
Below are a few 3D models to download. If you wish to follow the latest medical 3D printing news, you can follow Embodi3D on various social media platforms.
Thank you very much and happy 3D printing!
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A Collection of Free Downloadable STL Skulls for you to 3D print yourself.
3D printable human heart in stackable slices, shows amazing internal anatomy.
A Collection of Spine STL files to download and 3D print.
The sternum, commonly called breastbone, is a long and flat bony plate located on top of the heart and at the center of the chest. It connects the rib bones together and it functions in protecting the heart, lungs and blood vessels from physical trauma. However, certain conditions can lead to the disintegration of the sternum which include chest injuries and growth of tumor.
Researchers from the TangDu Hospital of the Fourth Military Medical University made the first 3D printed titanium sternum and implanted it on a 54 year old patient who suffered from an aggressive tumor which made the doctor decide to conduct the dangerous sterna surgery. Under the supervision of Dr. Wang Xiaoping, he also acknowledged the problem of the patient indicating that the removal of the sternum is appropriate due to the large tumor that can cause a lot of problems in the chest region including respiratory problems and heart problems.
To solve the problem, they created a 3D printed titanium alloy sternum which is the exact replica of the patient’s chest structure. To make the procedure challenging, this was the first ever procedure in the world thus careful planning was carried out by the researchers. They created a 1:1 scale 3D printed plastic model of the patient’s sternum before printing the final titanium sterna implant.
The surgery was successful and the patient is slowly recovering from it. It is believed that this was the first 3D printed titanium sterna implant ever conducted in the world and the Chinese doctors were successful in their endeavors.
Why do we need this? This is usually the first response you will get when asking to buy a 3D Printer. What are the benefits? Return on Investment? To show the benefits of having this capability in your center here is a look at one of the many cases I have our used our 3D Printers to create custom piece's and improve realism in our simulation scenarios.
As users of High-Fidelity Manikin's we all know these manikins are capable of replicating human patients with high realism. Unfortunately there are some limitations when using this equipment. Some limitations can cause a simulation scenario to go down a different route from what was intended.
Some simulation's require the scenario to be Can't Intubate, Can Ventilate, the goal being the physician using a specific algorithm for treatment. However I was finding that even with the difficult airways features turned on (laryngospasm, pharyngeal swelling, and tongue swelling) the physicians were able to pass the ET tube into the trachea with little resistance (video 1) *Disclaimer* There is resistance when attempting to pass the tube through the vocal cords, passing the tube with resistance would not take place in a clinical setting, however it does happen in simulation.
I attempted to find solutions to implement in addition to using the manikin features that could improve the realism and prevent intubation. The first solution involved making changes to the ET Tube. I cut the cuff (preventing a seal from being obtained). This solution did not work as it required opening the packaging of the supplies, and trying to prevent the staff from testing the cuff prior to intubation. Even with the modifications the physician was still able to pass the tube through into the trachea.
I decided to create a custom 3D printed piece that would prevent the tube from being passed. The manikin has a removable surgical airway that once removed exposes an opening behind the vocal cords (Figure 1).
The opening would allow a 3D printed piece to fit perfectly without interfering with any of the manikin features. Using digital calipers i measured the diameter of the opening as well length to the vocal cords.
There were multiple programs i could use to design the prototype, TinkerCAD, 123D, or Fusion360. I started creating a rough design in TinkerCAD, as it is web-based and simple to use. Using TinkerCAD did have some limitations and my first print failed due to the walls being too thin.
Design in TinkerCAD
My next attempt was using Fusion360. As with any prototype you will go through several designs before reaching the final one. Using Fusion360 provided me with greater control and more options for creating the prototype. Using the dimensions from TinkerCAD, I was able to easily create the prototype (see Video 2). The prototype has four holes that allow air to pass. Also included is a solid tube extending out to allow from the piece to be removed with forceps.
For the 3D print I decided to use the Formlabs 1+ SLA printer. My reasons for choosing this printer over the other 3D printers was for several reasons. First I wanted the prototype to be clear, second i wanted a flexible material that could be compressed to insure an airtight seal. And last using the Formlabs software allowed me to only have to select the material I wanted to use, all settings are changed automatically. If I used one of the other printers I would need to change multiple values manually to use a flexible filament. I have great results using the Formlabs printer, and I knew the prototype would be good quality. The print settings were:
Material: Flexible Resin v1
Layer Thickness: 0.1mm
Print Time: 59 minutes
Total Cost: $1.80/per print
Blockage Prototype-Printed on Formlabs 1+
(Left) TinkerCAD Design, (Right) Fusion360 Design
Testing the Prototype: To test the prototype. I inserted the piece into the surgical airway opening with the flat base facing the vocal cords. I attempted to intubate the manikin (video 3). The ET tube was not able to pass the vocal cords regardless of the amount of force applied. The prototype fit snuggly in the surgical airway opening (figure 2) providing normal manikin function without any restrictions.
Conclusion: The 3D Printed prototype functioned well during testing and during the simulation scenario's. The simple, low-cost design is achievable by using a 3D printer. The piece can be further modified to be used in a simulation that requires Can't Intubate, Can't Ventilate. Since there are 6 high-fidelity manikins in our center, all the manikins can be fitted with the piece for $10.80. There are countless ways to use a 3D printer in your center, this was just one example of the benefits the 3D printer can bring.
Written by David Escobar
Need Training? Contact me at david@3DAdvantage.org
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