A catheter can look perfect on the outside while still containing a critical defect hidden inside. For medical-device manufacturers, this creates a particular challenge: how can internal structures, components and assembly details be inspected reliably without cutting the product open or relying on destructive testing?
This is where X-ray technology provides a decisive advantage.
Compar AG has developed an X-ray inspection machine specifically for demanding industrial quality-control applications. By combining X-ray imaging with automated image processing, handling and machine-vision expertise, the system makes internal catheter structures visible and enables their reliable, non-destructive inspection.
Why is catheter inspection so challenging?
Catheters are highly sophisticated medical products. Depending on their application, they can contain several layers and components assembled into an extremely small diameter. Tubes, liners, reinforcement structures, wires, coils, markers and other functional elements may all be integrated into the catheter.
At the same time, the quality requirements are exceptionally high. Small deviations in the position, geometry or integrity of an internal component can affect the performance of the finished product.
From the outside, however, many of these critical features cannot be seen.
Conventional optical machine vision is extremely effective when the feature being inspected is accessible to a camera. Surface defects, dimensions, markings, contours and other external characteristics can be measured quickly and accurately. But a camera has an inherent limitation: it can only inspect what is visible.
When critical components are located inside the catheter wall, hidden behind another material or surrounded by several overlapping structures, optical inspection reaches its limits.
This creates a fundamental inspection problem:
The catheter may look correct externally while its internal construction does not meet the required specification.
Where conventional vision reaches its limits
Consider a catheter containing an internal reinforcement structure. From the outside, the surface may be completely flawless. Yet the reinforcement may be incorrectly positioned, damaged or incomplete.
The same applies to internal markers, wires, coils or other functional components. If they are enclosed by the catheter material, a conventional camera cannot reliably determine whether they are present, correctly positioned or correctly assembled.
The challenge becomes even greater when several components overlap. A camera image provides a two-dimensional view of the accessible surface, while the quality-critical information may be located beneath it.
Depending on the catheter design, features that are difficult or impossible to inspect optically can include:
- The position of internal components
- Reinforcement wires, coils or braided structures
- Embedded markers
- Internal interfaces between components
- Internal deformations
- Lumen geometry and potential obstructions
- Foreign particles or inclusions
- Assembly errors hidden within the catheter structure
Opening the catheter to inspect these features is possible in laboratory analysis, but it destroys the product and is therefore unsuitable for routine production inspection.
X-ray technology offers another approach: inspect the inside without destroying the outside.
X-ray makes the invisible visible
X-ray imaging works particularly well for complex assemblies because the radiation can penetrate the catheter and reveal differences between materials and structures.
Instead of seeing only the external surface, the inspection system generates an image of the internal construction. Components that are hidden from a conventional camera can therefore become visible in the X-ray image.
This makes it possible to inspect features that would otherwise require destructive testing or manual investigation.
The principle is simple, but applying it reliably in production is much more demanding. The X-ray image must provide sufficient contrast and resolution, the catheter must be positioned consistently, and the resulting image must be evaluated automatically according to defined quality criteria.
This is where X-ray technology and machine vision come together.
Inspecting the internal structure of a catheter
An automated X-ray inspection system can evaluate a wide range of characteristics depending on the catheter design and the customer's quality requirements.
Position and presence of internal components
One important application is verifying that internal components are present and located where they should be.
For example, a marker or other functional element may need to be positioned within a precisely defined area. X-ray imaging makes the component visible even when it is completely enclosed within the catheter.
The inspection system can then compare its detected position with the specified tolerance and automatically determine whether the part meets the requirements.
Reinforcement structures
Many catheters use internal reinforcement to achieve the required combination of flexibility, strength and dimensional stability.
These structures may consist of fine wires, coils or braided elements. Their small dimensions and location inside the catheter make them challenging to inspect with conventional vision.
X-ray imaging can reveal the reinforcement structure and make deviations such as unexpected positioning, discontinuities or other anomalies detectable.
Internal geometry
The internal lumen is another important quality feature.
An externally perfect catheter may nevertheless have an internal deformation, obstruction or unexpected change in geometry. Depending on the application, X-ray inspection can provide information about the internal shape and allow critical deviations to be identified.
Assembly and internal interfaces
Catheter construction can involve multiple layers and components that must work together precisely. X-ray inspection allows the internal arrangement to be checked without separating the components.
This provides manufacturers with an additional means of verifying that the actual assembly corresponds to the intended design.
From X-ray image to automated quality decision
Generating an X-ray image is only the first step. For industrial production, the real challenge is turning that image into a fast, reliable and repeatable quality decision.
This requires the combination of imaging technology and intelligent image processing.
A typical inspection sequence can be summarized as:
Positioning → X-ray acquisition → image processing → feature inspection → OK/NOK decision → automated handling
The catheter is positioned in the inspection area and an X-ray image is acquired. The image-processing system then analyzes the relevant features and compares the measured characteristics with the defined specifications.
Instead of relying on an operator to interpret every image manually, the system can make an automated inspection decision.
This is particularly valuable for high-volume production, where consistent inspection quality and productivity are essential.
Automation also makes the inspection process repeatable. The same inspection criteria can be applied to every part, reducing the variability associated with manual inspection and supporting a zero-defect manufacturing strategy.
A complete inspection solution from Compar AG
The strength of an industrial inspection system is not determined by the X-ray source or detector alone. The complete solution must bring together imaging, mechanics, automation, software and application-specific knowledge.
This is where Compar AG's interdisciplinary expertise becomes important.
As a system integrator for machine vision and robotics, Compar combines knowledge in automation, image processing and robotics to develop customer-specific inspection solutions.
For catheter inspection, this means that the X-ray technology can be integrated into a complete automated machine rather than being treated as a standalone imaging component.
The system can incorporate the necessary part handling, positioning, image acquisition, image processing and inspection logic required for the application. Depending on the production requirements, the inspection can be integrated into an automated manufacturing process.
Compar's modular approach also makes it possible to adapt the solution to different products and inspection requirements.
Combining X-ray technology with machine vision and robotics
X-ray inspection does not replace conventional machine vision. Instead, the two technologies complement each other.
Optical vision remains highly effective for inspecting accessible surfaces and visible characteristics. X-ray adds another dimension by making internal structures accessible to automated inspection.
Robotics and automation then connect the inspection process with the production environment.
The result is a complete inspection concept:
Machine vision for what is visible. X-ray for what is hidden. Automation and robotics for a reliable production process.
This combination allows Compar to address complex quality-control tasks that cannot be solved effectively with a single technology.
Non-destructive inspection for demanding medical applications
For medical-device manufacturers, non-destructive testing can be particularly valuable. The product remains intact during inspection, while critical internal characteristics can nevertheless be evaluated.
This opens the possibility of inspecting features that would previously have been checked through sampling, manual examination or destructive analysis.
The benefits include:
- Visibility of hidden internal structures
- Non-destructive inspection
- Automated and repeatable quality decisions
- Detection of internal assembly deviations
- Support for zero-defect strategies
- Reduced dependence on manual inspection
- High productivity
- Potential integration into automated production processes
The exact inspection criteria can be adapted to the catheter design and the manufacturer's quality requirements.
When conventional vision cannot see far enough
Catheter inspection illustrates a broader principle in industrial quality control: sometimes the most important quality features are simply not visible from the outside.
A conventional camera can provide an excellent image of the catheter surface, but it cannot look through the product. When wires, reinforcement structures, markers, interfaces or other critical components are hidden inside, another inspection technology is required.
X-ray provides that additional view.
By combining X-ray imaging with automated image processing, Compar AG transforms this capability into an industrial inspection solution. The result is not simply an X-ray image, but an automated system capable of detecting relevant internal characteristics and supporting reliable quality decisions.
When critical quality features are hidden inside a product, X-ray inspection makes it possible to see what conventional vision cannot — without destroying the part.
Compar AG combines X-ray technology, machine vision, automation and robotics to develop flexible inspection solutions for demanding applications in medical technology and other industries.