Scale replicas made with a 3D printer: this is how the tumor is explained to a patient

The first thing is to get over the shock; then understand what happens. When a patient learns that he has a tumor, in addition to assimilating it, he faces the challenge of understanding what is wrong with him and how his doctors will try to remedy it. The replicas and models made in the Advanced Planning and 3D Manufacturing Unit of the Madrid public hospital Gregorio Marañón are used for this. Starting from a model developed on the computer, the printers allow doctors to obtain life-size replicas of their patient's organs, veins or arteries. With them, not only do they explain to the affected person what happens to him and how the surgery to which he is going to undergo is going to be, but also makes it easier for health teams to agree before the operation in a simpler and more visual way and to elaborate surgical guides. And all without leaving the hospital.

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3D printing is known as

, since it builds objects layer by layer.

'' The advantage of this is that it serves as a communication tool with the patient and for case planning, as well as to manufacture tailor-made solutions.

That is the most ambitious of what we do here: we design and manufacture medical devices and even implantables that the patient wears, and they are unique because they have been designed exclusively for him '', explains Rubén Pérez-Mañanes, coordinator of the Unit and orthopedic surgeon cancer center.

The first step to obtain that copy of the patient's anatomy on a real scale (something they call a

) is to develop a digital copy through the computer.

For this, it is essential to have done a radiological study: a CT (computerized axial tomography) or an MRI.

The doctor then provides that digital image to the Unit's biomedical engineers.

In this case, Estela Gómez Larrén and Iago González Fernández.

They are in charge of programming the 3D printers, which use FDM and SLS technology.

The first consists

, the most common technique in 3D printing, and the second in

, which allows the construction of complex and resistant parts.

'' Printing a model can take six to eight hours.

If in one morning we have worked on the model, maybe the next day we could have the impression.

It is very fast and tailored, both for the patient and the doctor, '' explains oncological and liver transplant surgeon José Manuel Asencio Pascual.

In the center, José Manuel Asencio and Rubén Pérez-Mañanes and, at the ends, Iago González Fernández and Estela Gómez Larrén, pose in front of one of the printers of the Hospital's 3D Printing Unit.

These models can be assimilated to a kind of "GPS of what is happening," according to Asencio, who regularly uses them. The biomodels allow them to see very clearly '' where the arteries and veins are or what structures we are going to treat, for example, so that a very customized and very safe surgery is done, which are the two things that interest us '' he insists.

Although explaining the disease with a replica of their own organs on a real scale, being able to see the size of the tumor with their own eyes, could seem something difficult for the patient to assimilate, Dr. Asencio assures that precisely being able to do that is one of the benefits that they detected from the beginning: '' The majority welcomes him. When you tell someone they have a caval tumor, most don't even know what it is, but when they're seeing it like this, it's pretty obvious. They can see where it is going to be cut, how the prosthesis is going to be put on by joining one end to the other ... It gives them a lot of peace of mind when they understand what is going to happen to them. The patient experience is so much better. ''

Models do not have to be actual size, but that size is usually chosen.

According to Asencio: '' We can make them smaller or larger, but normally we are interested in working on a real scale.

For example, in the case of prostheses, it is obvious to be able to make them to measure.

Sometimes we make models to teach or for a congress, and in that case they can be smaller. ''

Biomodel of a tumor (in red) in the vena cava CR

Printing can be done with different materials, but for these models it is common to use plastic. If it is an implant that the patient is going to wear, the materials should be biocompatible with the tissues and fluids of the human body, such as some types of ceramics, resin and methacrylates. At the moment, the unit does not manufacture implants, although it is working on it: '' The implantable material is outsourced, what will remain in the patient later we design here, but the printing process is outside. The idea is that, over time, that will also be in the Hospital, '' says Asencio. "Now we are making the leap to the manufacture of implantable products by means of metal impressions: hip prostheses, spine, metal surgical guides ...", continues Pérez-Mañanes.

This plan for the design and manufacture of personalized implants will be one more step in the unique and personalized attention that the Unit team defends.

"It is a very useful tool that can help save lives in the operating room, so we must bet on this," insists Gómez Larrén.

According to the head of the Unit, one of the most innovative aspects is that there are no specific profiles: '' At a professional level this has not yet been defined.

It is a beautiful moment because new professional profiles, teams and multidisciplinary units are beginning to be created… It is not so much that someone has to know how to do it, but rather that we put together a team and that together we all have all the knowledge of the process.

It is a more transversal way of working. ''

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