What are X-rays?
X-rays are photons similar to light but with higher energy. They are produced by accelerating electrons which then strike a target. Removing electrical power stops any X-rays being produced. X-rays are attenuated (or absorbed) in different ways depending on the energy and the type of material it is passing through. Higher density materials, with more atoms in the material, will absorb more than low density materials.
Quantitative Dual-energy X-ray Absorptiometry (qDXA)
qDXA uses two X-ray beams, each with a different energy, and two high resolution detectors, to measure the amount of photons absorbed in the organic material. The software can then measure the amount (quantity) of the selected atoms – usually oxygen and carbon. As the material moves under the scanner clever algorithms calculate various physical parameters such as weight, moisture, energy value etc.
In addition, the technology also provides for a visual picture (like a normal X-ray image) which allows us to identify material with higher densities – usually debris such as metal and plastic.
The scanners are calibrated and verified against accepted measurement techniques such as the gravimetric (oven) method.