Fraunhofer Development Center X-Ray Technology EZRT, Division of Fraunhofer Institute for Integrated Circuits IIS, Fürth, Germany

Anyone who has flown in the last few years, or has ever broken a bone, knows that X-rays are a tested method to investigate images. Researchers at the Fraunhofer Development Center X-Ray Technology EZRT, are now developing an X-ray detector that, they say, is capable of delivering high-quality 3D images in real time. They say that this will make it possible to precisely reconstruct even the processes going on inside materials and can provide a reliable way of detecting miniscule faults.

The MULIX X-ray detector is designed to be integrated into industrial computed tomography systems. This hybrid solution combines the advantages of single-line and flat-panel detectors. Its adjustable curvature enhances the image quality while maintaining full flexibility. (Credit: Fraunhofer EZRT)
In healthcare, X-rays provide high-resolution images of our bodies to help doctors make a definitive diagnosis. Industry also uses X-rays, as a reliable, nondestructive way of seeing what’s hidden inside materials and components and to check for cracks or irregularities.

However, industry also draws upon different technologies that are not used in the medical field. Whereas medical Xray machines have been specifically designed for human test subjects, industrial X-ray machines are used to analyze objects that vary much more in their size and material composition. This calls for X-ray equipment that is correspondingly more flexible.

The Fraunhofer EZRT researchers have developed MULIX—an X-ray detector for industrial computed tomography (CT), which is based on the design of medical X-ray devices.

“Our challenge was to combine high image quality with a high degree of flexibility,” explains Frank Nachtrab from EZRT. MULIX harnesses two concepts already in use, making it a hybrid solution that incorporates elements of line and flat-panel detectors commonly used in industry. The researchers already know what they plan to achieve with their work: “We’ve had very promising results with our demonstrator and have shown that MULIX works. We’re now looking for industrial partners to help develop a MULIX prototype,” says Nachtrab.

Combining Benefits of Two Methods

Single-line detectors use a fan-shaped beam to X-ray a certain section of the test object, while flat-panel detectors work with a cone-shaped beam that encompasses the entire object. There are pros and cons to both solutions. A flat-panel detector can quickly give you a 2D image of the entire object. However, it causes scattered radiation, which can greatly impair image quality. A single-line detector is less sensitive to scatter and will, therefore, deliver extremely sharp images. But, because it captures only a small portion of the test object, this scanning method can be much more time-consuming.

“We have combined the benefits of the two solutions,” says Nachtrab. The new equipment is based on a detector with multiple lines, which until now has been only used in the medical field. Multiple-line detectors work according to the same principle as their single-line counterparts, but can cover larger areas and radically reduce scanning time. MULIX uses a total of 256 lines, allowing it to scan larger objects, such as car body parts, very quickly. What’s really remarkable is that the new detector delivers images so quickly, the researchers say that it becomes possible to use CT techniques to make a nearly real-time 3D scan of the object.

MULIX opens up new application opportunities in materials research and quality assurance, which would allow multiple industries and research institutions to observe processes going on within the materials they use.

“When testing mechanical properties such as tensile strength, we can use the images we get to see just how a compromising fault comes about,” says Nachtrab.

The researchers came up with one more innovative solution for the technology. Unlike commercially available detectors, it is possible to adjust MULIX’s curvature, which ensures the flexibility that industrial CT needs to adapt the system to the various sizes and material properties of test objects.