As a stent is a life-saving device, stent engineering and development accuracy are vital for the overall functionality of the device. Medical device manufacturers have to verify the quality and function of the stent as well as take into account the precision of the delivery device that is used to implant the stent into the artery.
Most stents are made up of nitinol and platinum metal. The metal structure is squeezed down in a delivery device and implanted into an artery. After it is placed into the artery, the stent expands to open up the blockage and holds the structure together. This enables the blood to flow freely and heal the body.
Stent X-ray Inspection
When imaging a stent, most medical manufacturers are concerned about the intersection points wherein one nitinol wire crosses the other to characterize the wire wear that can occur over time. Manufacturers are also concerned about wire fractures or defects. Stents are made by using laser cutting or etching, and hence, it is necessary to measure the accuracy of the cuts and identify any nicks or burs that are protruding and could cause harm to a patient or develop stress risers that will fail in service.
X-ray is used to examine the delivery devices, and helps a manufacturer to see the inner and outer details of the handle, small laser welds, cables, and plastic-injected molded parts of the delivery handle. 4D X-ray technology helps to observe the stent deployment action as if it were being directly inserted into the artery.
Each stent has a different shape or flexibility. After CT scanning the stent, a finite element analysis (FEA) can be performed using the real-world data set from the CT scan. The FEA software uses a simulated computer program to observe if the stent bends or twists too much and if it will fail or break with its level of flexibility.
With the advent of new stent materials, such as absorbable stents, CT scanning has become an effective non-destructive testing technology to avoid failure.
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This information has been sourced, reviewed and adapted from materials provided by North Star Imaging, Inc.
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