Industrial CT Scanning: Defining Porosity of 3D Porous Structures For Medical Implants Using Advanced Metrology Methods

Additive manufacturing and other innovative manufacturing methods are used to create porous structures of medical implants that promote bone ingrowth. The effectiveness of these structures is determined by taking 2D cross-sections of harvested implants and performing calculations to define pore size and interconnectivity. Researchers analyze the 2D cross-sections to check how far bone has grown into the spaces.

A shortcoming of this method is that 2D cross-sections do not show all areas of an implant. As a result, researchers are unable to evaluate the entire structure. Due to this reason, many researchers rely on 3D CT scanning to measure the effectiveness of porous structures as well as to optimize their printing process.

Industrial CT scanning is one of the most advanced metrology methods used to define the porosity of 3D porous structures for medical implants. A 3D CT scan allows researchers to view the external as well as internal structure of implants, enabling them to analyze porosity and inclusions. Defects can be easily seen as well as quantified. Traditional methods may necessitate destroying samples to gain this information. There is a possibility that the operator may make a mistake (that could affect the accuracy of the test) while mounting the sample.  

Here is a step-by-step guide to defining the porosity of 3D porous structures for medical implants.

Sample Preparation

An entire sample can normally be imaged at once, however researchers can also cut down a sample into sub sections should it be required for their application.

Micro-CT Imaging

Micro-CT is used to non-destructively capture high spatial resolution images of the internal structure of the porous material. It allows researchers to accurately measure pore size, shape, and their distribution within the structure.  

Image Analysis  

Using advanced software, researchers segment the pore spaces from the solid matrix. Segmentation of pore spaces enables quantitative analysis of pore characteristics including surface area, connectivity, sphericity, and volume. From total porosity parameters on an entire part to individual pore properties, a graphical representation can be achieved according to the user's needs.

‍Data Interrogation

Data files are shared with the customer along with free viewer software. Nel PreTech will meet with the customer in person or via online to introduce them to the viewing software and provide some initial guidance as to how the porosity analysis was performed and what the results were. Sometimes, it can be an iterative process depending on what the customer needs. This may include changes to parameters or porosity on a certain scale or size, in which case the analysis can be fine tuned.  

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The Nel PreTech team comprises physicists, mathematicians, and technical science experts. We are equipped to carry out complex analyses. To request a quote, call 708-429-4887.