Three Ways Helical Scanning Can Improve Your MicroCT Materials Science Results

MicroCT in materials science

Micro-computed tomography (microCT) has revolutionized materials science, giving researchers quick and easy 3D X-ray images of almost any structure—without the need for staining, slicing, or cross-sectioning. With the ability to visualize the internal structure without damaging the sample, micro-CT has become an essential quality control tool in the production of complex machined and molded parts.

Heliscan helical scanning

Today’s researchers typically use micro-CT to identify voids, porosity, and cracks before these flaws turn into catastrophic failures. And as more materials scientists embrace microCT as part of their failure analysis process, advanced helical scanning with iterative reconstruction technology is bringing micro-CT into a new era by providing once unobtainable high-fidelity images.

How microCT works

MicroCT produces images by transmitting X-rays onto a sample and recording the X-rays that pass through it using a detector on the other side. The sample is then slightly rotated, another is image taken, and the process repeated to create a series of images that are then combined using software to form a 3D image.

MicroCT produces 3D images based on the fact that harder materials absorb more X-rays and lighter materials allow more X-rays to pass through.

Advantages of helical scanning

Helical scanning takes microCT to the next level with a more sophisticated scanning technique. Unlike conventional circular microCT scanners, which typically scan the sample at its midpoint, helical scanning provides a spiral route that covers the whole sample from bottom to top, using algorithms to create a seamless image composed of data that’s consistently in focus.

Helical scanning can significantly improve researchers’ failure analysis results. Here are three main advantages it offers over circular scanners:

Unsurpassed image fidelity. Helical scanning brings the detector much closer to the X-ray source than a circular scanner, reducing the number of unused X-rays and achieving a better signal to noise ratio. With helical scanning, every part of the test piece has the sample’s optimum X-ray image projected onto the detector, meaning that every part of the image is in focus. What’s more, no stitching of multiple images is required, eliminating the errors that result from circular scanners. Instead, the sample is rotated in a helical formation with the integrated algorithms turning the data into a seamless final image.

MicroCT helical scanning compared to typical microCT

Using a helical scanner, materials scientists can bring the sample and detector closer to the source, improving X-ray efficiency and obtaining the highest signal-to-noise ratio.

The versatility required to study a wide variety of samples. Helical scanning can also handle a wider variety of samples, making it quick and easy to identify defects inside complex shapes. Researchers can obtain high-resolution images of the internal parts of everything from solid objects to both high-density and low-density materials. For low-density materials, researchers can change the tool’s X-ray source from tungsten to lanthanum hexaboride for a dramatically improved resolution at high magnification. Helical scanning can also work on large samples up to six times faster and with higher accuracy than circular scanners—with the whole object in focus the first time.

Aluminum-silicon composite in a lithium battery imaged with microCT

An aluminum-silicon composite in a lithium battery visualized with a standard tungsten filament (left) versus a lanthanum hexaboride filament X-ray source (right).

Accurate and precise measurements. In addition to providing in-depth analysis of internal structures, helical scanners can be used as a measurement tool, producing exact measurements of the internal dimensions of specific components without the need for sample preparation. This makes it a useful tool for characterizing faults during the manufacturing process.

Using a helical microCT scanner, materials scientists can clearly see details that were once hidden by grainy images. Combined with their versatility and ability to produce high-accuracy measurements, helical scanners enable scientists to more quickly and precisely identify failures within the whole sample. The result is reduced costs and improved productivity of the entire quality control process.

To learn more, please read our “Helical Scanning with Iterative Reconstruction Technology” whitepaper.

Dirk Laeveren is product marketing manager, HeliScan microCT, at Thermo Fisher Scientific.

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