Scattered X-rays captured to enhance hyperspectral imaging

Manchester and Didcot, England--Using an 80 x 80 pixel cadmium zinc telluride (CdZnTe) camera they previously developed for X-ray work, researchers at the University of Manchester and Rutherford Appleton Laboratory have figured out a way to identify different specific atomic elements using X-ray radiographic and scatter imaging.¹ The setup could be used for security, materials science (corrosion detection), medical science (cancer detection), and many other fields.

The camera supports real-time hyperspectral imaging to X-ray energies higher than 70 keV, encompassing many atomic absorption edges and other spectral features. The hyperspectral (2D spatial and 1D spectral) images have enough extra information (when compared to images at single energies) that the researchers can use multivariate analysis to find data groups based on spectral similarity. A standard lab X-ray tube serves as the light source, making the setup relatively compact (especially when compared to the size of an X-ray synchrotron source).

The system can identify chemicals and compounds such as cocaine, semtex, precious metals, and radioactive materials even when they're contained inside a relatively large object like a suitcase. The method could also be extended to detect strain in fabricated components, for example in aircraft wings, and it can be used to image corrosion processes and chemical changes.

Analyzing a dongle

In a recent experiment, the team used the technology to X-ray a USB dongle that controls webcams. They were able to identify the different elements and components inside the dongle by analyzing the energy sensitive radiographs and fluorescence patterns. The elements or components were highlighted in different colors to clearly identify them to the system operators. In this case the X-ray showed bromine, barium, silver, tin, and zirconium.

"Current imaging systems such as spiral CAT scanners do not use all the information contained in the X-ray beam," notes Robert Cernik, one of the researchers. "We can use all the wavelengths present to give a color X-ray image in a number of different imaging geometries."

As well as providing more information about the object being X-rayed, this new technique also decreases the time it takes to create a three dimensional image. Rather than building up lots of separate images (mapping), the new system creates the image in one simple scanning motion that takes only a few minutes.

Cernik is seeking industrial partners for collaborative projects to refine the X-ray technology for each specific application such as security, aerospace, and medical imaging. The team is also close to creating the first color CT scanner, which could dramatically improve diagnosis for a range of conditions or improve security at airports.

REFERENCE:

1. Simon D. M Jacques et al., Analyst, 2013, 138, 755; DOI: 10.1039/c2an36157d