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Fast Baggage Scanning: Mathematics Crucial to Airport Baggage Screening

Fast Baggage Scanning: Mathematics Crucial to Airport Baggage Screening

By Prof Bill Lionheart (University of Manchester)

In 2005, a Surrey University spin out company CXR approached us at the University of Manchester for help developing a fast x-ray tomography system. Coming from a perspective of highly non-linear and ill-posed imaging problems my first (and naive) reaction was x-ray CT (Computed Tomography) was quite simple . What drew me in to the problem was the novelty of the geometry. A conventional hospital x-ray CT  system has an x-ray source and array of detectors mounted on a mechanically rotated gantry, and this limits its rotation and hence scanning speed. The Real Time Tomography (RTT) system developed by Ed Morton and his team had a fixed array of x-ray sources which were electronically switched. The down-side is that the detector array has to be offset from the ring of sources rather than opposite, and there was no theory nor reconstruction algorithm for for this case.

The original idea of the RTT was to monitor oil, water and gas in pipes in the petroleum industry but  CXR was bought by the major security screening company Rapiscan Systems, in the wake of an increased interest in improved baggage screening following 9/11, with the intention of developing a fast 3D baggage scanner. In a joint EPSRC and Rapiscan funded project worth £750k over three years we developed novel reconstruction algorithms, optimal measurement schemes and scatter correction algorithms for the RTT, which were patented and published. By the end of the project there was a production prototype baggage scanner. After regulatory approval the RTT 110 went in to production at its UK factory and is now deployed in airports around the world scanning hold luggage on a conveyor belt in real time.

At Manchester the work widened our  interest in x-ray CT algorithms especially for materials and advanced manufacturing in collaboration with the Henry Mosley X-ray Imaging Facility. We now have our own RTT 110 which is being tested and adapted to do fundamental science such as looking in to the mysteries of granular materials and two phase fluid flow, as well as rapid non-destructive testing for manufacturing.

Interdisciplinary projects are always more challenging, mainly due to communications barriers. This is true even more so in collaborations between industry and academia ,but if you meet these challenges, the rewards are worth it.

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Prof Bill Lionheart is Professor of Applied Mathematics, University of Manchester.  He specialises in inverse problems and imaging across a wide range of applications including security screening, medical imaging, non-destructive testing, and land mine detection. EPSRC Grant Information: EP/E010997/1 Title: X-ray CT reconstruction algorithms for airport security and process tomography. This was a special maths with industry EPSRC maths programme call.  500k from EPSRC and 250 k from Rapiscan

Selected references

  1. Nicola Wadeson, Edward Morton and William Lionheart Scatter in an uncollimated x-ray CT machine based on a Geant4 Monte Carlo simulation. In: SPIE Medical Imaging 2010: Physics of Medical Imaging, 15-18 February 2010, San Diego, USA.
    MIMS e-print: 2010.66
  1. William M Thompson, William RB Lionheart and Edward J Morton, Real-Time imaging with a high speed X-Ray CT system. In: 6th International Symposium on Process Tomography, 26 – 28 March 2012, Cape Town, South Africa.
    MIMS e-print: 2012.36
  1. WM Thompson, WRB Lionheart, EJ Morton, High-speed dynamic imaging with a real time tomography system, Proceedings of the Second International Conference on Image Formation in X-Ray Computed Tomography, June 24-27, 2012, Salt Lake City, Utah, USA , p99-102.
    MIMS e-print: 2015.45
  1. William M Thompson, William RB Lionheart, Edward J Morton, Mike Cunningham and Russell Luggar, High Speed Imaging of Dynamic Processes with a Switched Source X-ray CT System, Measurement Science and Technology 26 055401 2015 DOI: 10.1088/0957-0233/26/5/055401

Patents

  1. Marta Betcke, William Robert Breckon Lionheart, Edward James Morton ,System and method for image reconstruction by using multi-sheet surface rebinning  Patent number: 8559592, Filed: January 9, 2012 , Date of Patent: October 15, 2013
  1. William Thompson, William Robert Breckon Lionheart, Edward James Morton, Optimization of the Source Firing Pattern for X-Ray Scanning Systems,Publication number: 20120219116 Type: Application Filed: February 24, 2012 Publication date: August 30, 2012