Future of Engineering
Thursday, March 20, 2008
How X-rays Can Detect Cocaine or Semtex in a Suitcase
Bob Cernik likes using x-rays to probe the nature of materials. The Manchester University professor has been working at the Diamond Light Source synchrotron in Oxfordshire to develop a prototype 3D colour x-ray system to detect hidden explosives, drugs, or even cancer. But wait a moment ... x-rays, in colour and three dimensions?
How does a hospital x-ray CAT scanner produce colourful 3D body images? It's a process called "false colour", where shades of grey are converted to a corresponding colour in the normal spectrum. This gives you a high spatial resolution density contrast image that is often false coloured to aid diagnosis. But it is a false colouration.
There are other x-ray techniques, including diffraction, that allow scientists to identify materials.
All these current imaging systems do not however use all the information contained in the x-ray beam. This extra information can be used to fingerprint the material present at each point in a 3D image.
To do this with x-rays, Cernik's system uses "tomographic energy dispersive diffraction imaging" - or TEDDI. He works with "voxels" (volumetric pixels) which represent points in three-dimensional space. TEDDI measures voxels throughout a sample so that each contains an x-ray diffraction pattern - the key to identifying a material's atomic structure and chemistry.
Many experts think TEDDI is excellent work which produces very accurate results.
Some related work is going on to develop the world's first "scatter-enhanced" 3D x-ray security scanner. This method also uses x-ray diffraction but concentrates on the high-speed identification of substances in cluttered scenes - like the insides of suitcases.
Typically, X-rays pass through and are scattered by the contents but, compared with the primary beam, the scattered signals are extremely weak. These new techniques to produce 3D x-ray images with materials to quickly identity information in them.
Read more about these new techniques from here
How does a hospital x-ray CAT scanner produce colourful 3D body images? It's a process called "false colour", where shades of grey are converted to a corresponding colour in the normal spectrum. This gives you a high spatial resolution density contrast image that is often false coloured to aid diagnosis. But it is a false colouration.
There are other x-ray techniques, including diffraction, that allow scientists to identify materials.
All these current imaging systems do not however use all the information contained in the x-ray beam. This extra information can be used to fingerprint the material present at each point in a 3D image.
To do this with x-rays, Cernik's system uses "tomographic energy dispersive diffraction imaging" - or TEDDI. He works with "voxels" (volumetric pixels) which represent points in three-dimensional space. TEDDI measures voxels throughout a sample so that each contains an x-ray diffraction pattern - the key to identifying a material's atomic structure and chemistry.
Many experts think TEDDI is excellent work which produces very accurate results.
Some related work is going on to develop the world's first "scatter-enhanced" 3D x-ray security scanner. This method also uses x-ray diffraction but concentrates on the high-speed identification of substances in cluttered scenes - like the insides of suitcases.
Typically, X-rays pass through and are scattered by the contents but, compared with the primary beam, the scattered signals are extremely weak. These new techniques to produce 3D x-ray images with materials to quickly identity information in them.
Read more about these new techniques from here
Labels: Physics
PermaLink - How X-rays Can Detect Cocaine or Semtex in a Suitcase posted by Ecacofonix : 11:26 PM
