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Dual energy x-rays gain traction

21 November 2022

Gareth Jones offers his thoughts on the next big technology development for product inspection equipment in food processing applications. 



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Although dual energy x-ray is not completely new as a product inspection technology, it is starting to gain more and more traction with food manufacturers due to its ability to help identify and reject certain types of contaminants that traditionally have been hard to find. So, the importance of dual energy x-ray for improving food safety standards, reducing waste and avoiding product recalls is growing.

Dual energy x-ray is suitable for some specific application such as for detecting low-density foreign bodies such as bone, aluminium, low mineral glass and rubber. It is also well-suited to applications where the product is multi-textured or overlapping – such as bags of dry pasta, frozen potato wedges, chicken breasts and sausages which produce a ‘noisy’ x-ray image within which low-density contaminants can be hidden in the noise.

In simple terms, dual energy takes two images – one classed as low energy, the other as high energy. Each material in the images, in the host product material and the contaminant material, will generate a different material curve relative to the x-ray energy. Software then compares and analyses the images produced and can remove the dominant material, which is the host product itself, from the image. What is left visible is the contaminant.

Typically, there are two different levels of dual energy x-ray – standard dual energy and advanced dual energy. Standard dual energy is based on existing x-ray technology and can usually be used in the same environments and operating conditions as single energy x-ray. Detecting low density contaminants in those noisy product applications therefore becomes viable with dual energy x-ray.

Advanced dual energy x-ray features radically enhanced detector technology – smaller diodes with a smaller pitch can collect more detailed product data. Combining this with advanced image analysis software provides clearer images with much higher resolution. This level of x-ray is designed to detect contaminants in the most demanding of applications, where the very best performance is required.

Big benefits
The potential business benefits for food manufacturers with the right applications are significant. Food safety is, of course, a benefit to consumers and to society at large, but for the food manufacturer it has implications also in terms of business reputation along the supply chain and brand protection. Using cutting-edge x-ray technology to improve the ability to detect hard-to-find contaminants makes product recalls less likely and strengthens the reputation of the manufacturer. 

Added to the reputational boost is a cost-efficiency boost. Dual energy x-ray can help to reduce false reject rates on the production line and therefore save on unnecessary product throwaway and the inherent costs of this waste.

Gareth Jones is head of engineering at Mettler-Toledo Product Inspection.


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