Blog Archives

Impression of the Science Fair

The Science Fair, october 27th, was the chance for us to present our work to our collegues and other interested people. For this event we made two informative posters which showed the global process we went trough, from scan to printable CAD-model. We also displayed our prints, including the latest, just finished improvement of the previous heart. There was quiet some interest in our project, and it was nice to get some critical questions to answer, like: what value can this really add to the existing products? Instead of some other projects, no media attention was given to us. It was nice to see all the other projects, and to see all the people that passed by and took a look to this Science Fair.

 

SAMSUNG CSC

SAMSUNG CSC

SAMSUNG CSC

SAMSUNG CSC

SAMSUNG CSC

SAMSUNG CSC

SAMSUNG CSC

Printing….

 

New prints

Last friday we finally recieved our heart, complete with valves. A nice side product of printing with the connex is that you literally have to unpack your exciting present.

So after some time, the heart slowly appeared out of the solid mass. We were quite satisfied with the result. The valves where looking good and the coronary arteries where quite clear too.

Ofcourse it is not a perfect print, which was confirmed after showing it to the cardiologists. Some valves were not positioned correctly and the coronary arteries were not perfect too.

IMG_4873

IMG_4868

CC; Creating Coronary

The coronary arteries have a very complex structure and are lying around the myocard of the hearth. The coronary arteries can be split into two parts: the right coronary artery and the left coronary artery. They both begin in the aortic sinuses respectively the left and right aortic sinuses. The middle aortic sinus doesn’t have a connection with a coronary artery.

The right coronary artery is follows the border between the right atrium and right ventricle in the sulci of the hearth. When the sulci is reaching the interventricular septum of the hearth the sulci and the right coronary artery is turning and follows his way on the interventricular septum as the posterior interventricular branch of the right coronary artery.

The left coronary artery splits into two veins: the Circumflex branch of left coronary artery and the anterior interventricular branch. The Circumflex follows the border of the left atrium and the left ventricle in the sulci of the heart. The end of the Circumflex is near the spot were the posterior interventricular branch of right coronary artery at the interventricular septum.

The anterior interventricular branch is following the sulci on the interventricular septum of the hearth. The interventricular branch ends near the end of the posterior interventricular branch of right coronary artery.

These 3 veins are the main veins of the hearth. They split up in multiple branches that are going into the myocard to muscles of the heart of blood. For the printed model it is only necessary to visualize these tree veins, because it is very heart to see which way the branches are following.

Connection lost

After we had made the valves which fitted every heart that could be modelled we faced the next challenge: to print you need a solid. We could place the valves at the right place but the problem was that both the surface of the heart and the surface of the valve were intersecting with each other. When we tried to mesh Boolean in rhino the fan from your laptop creates such a lifting effect that your laptop actually begins to float or it spontaneously combusts. So we came to the conclusion that we needed to search for another solution that using Rhino.

connection lost intersect

Our friends from Autodesk had the ideal program which we could use to mix the meshes, join them, or Boolean difference them. This program helped us throughout the rest of the project and was our savior. Every patch that needed to be done, every Boolean difference or union, this program would fix everything for us.

intersect

A bit offsetting

ofsetting

Each and every model that is used in anatomy classes uses colours to give a visual representation of the oxygen deprived and enriched parts of the heart. This is also what we wanted to create in our model, give a good representation of which part of the heart does what and which colour fits this. To do so we needed to cut the atria and ventricles from the hearth, give them an offset and make them in to a solid. This sounds like a pretty straight forward job, it turned out the other way. Because of the very complex shape the parts of the heart has creating an offset in Rhino was a hard task. After a lot of tinkering, mending holes and patching stuff finally it was done. An offset ventricle and atrium on the right and left side. Each part was Boolean differenced with the whole heart so there was no overlap and the atria and ventricle where separate layers so they could both be given an individual colour.

Open the valves

spuit

To give an accurate representation of the human heart it needs it valves. The hearth has four valves which are in different places and have different sizes. Each of the valves is connected to the hearth or even to each other. Seen the fact that every heart of every human is different we needed to make a system where we modelled the valves and could deform them later without losing their generic shape.

Prepwork

plamuurmes

The scans from the LUMC were in, downloaded and ready to work with. To make a printable file the scan needed to be ONE surface, the problem still was that the CT scans gave us an image which consisted out of multiple smaller surfaces. A lot of cleaning needed to be done, but how. Rhino is a beautiful modelling program but when it comes to meshes it offers us not so much, and so the next search for a modelling program which could model meshes in a quick and easy manner began. After downloading multiple trails, and have tried many programs we found the savior, geomagic. Geomagic offers many platforms on which you can work with meshes. This is where we found the program which we use by now. The program deforms the mesh into a clay shape which could be stretched and moulded. We patched the holes in the model, made it a solid and converted into a smooth and beautiful STL file. Now the real work began…….

It’s a big mesh

In last weeks submitted piece you could read for our quest of a remodel able model of the human heart. There were three fields to look in to before making a decision on which path we wanted to choose. After a lot of research, struggling, downloading 100+ trails for programs and 400 liters of coffee the die is casted! Finally the next steps in the search for the ultimate didactical model for the LUMC are made.

The ideas for a NURBS model are cleared out of the way. Why, would you say. Simply because of the fact that a good NURBS model costs a lot of money and there is no certainty that the NURBS could be re modeled the way we needed. The idea for building a NURBS model ourselves was also cleared of the table because it would take too much time to repeat this step for every patient and with every heart.

Then the final big option was the one we started initially with: The scans from the heart. The problem with the scans is that they are grainy, have a lot of noise and you cannot keep track where the heart starts or ends. This thanks to the fact that the heart moves. It also is inside of an human body surrounded by organs and muscles which al have fairly the same density as the heart itself. So therefore only the Lumens (the cavities where the blood rushes through) are really visible in the scans. The challenge was set: How could the scans get better so we could work with a more detailed mesh?

The LUMC has an unique collection of un-operated hearts with an congenital heart disease. Al these hearts are deprived of blood and plasticized. So in deliberation with our client we asked if the plasticized hearts could be scanned, because of the lack of surrounding tissue and blood, maybe this would help bring the noise down and give us an more detailed scan. And so it was that we got a beautiful scan last week from the LUMC.

First prints

Hi!

Our first test prints arrived from the printer today.

The slice of the heart looks pretty neat. We also printed some test structures to see how thin we could print and how it behaves with different materials (different stiffness). Removing the support material becomes the biggests issue with ultra thin rods.

 

Slice of (baby) heart:

20151013_102656b

20151013_102707b

Modelled tricuspidalus (valve between right atrium and right chamber)

20151013_102748b

 

Test sample with different thicknesses:

20151013_102724b