Physical Background

  • Thorsten R. C. Johnson
  • Willi A. Kalender
Part of the Medical Radiology book series (MEDRAD)


There had been attempts to utilize spectral information for tissue characterization soon after the invention of Computed Tomography, but only recently Dual Energy CT has achieved a significant role in clinical radiology.

To perform Dual Energy CT, it is necessary to generate x-rays with different energies, mostly as polychromatic spectra. On the other hand, the detector has to be capable to differentiate x-ray quanta of different energies. There are four technical approaches to meet these requirements, of which the Dual Source CT, the rapid voltage switching and the layer detector technology are available or being implemented.

To obtain relevant diagnostic information, there have to be substances with spectral properties which reflect the pathology by their presence or distribution. Most important is the photoelectric effect of elements like uric acid, iron, calcium, iodine or xenon gas, which are present in pathological structures or can be administered as contrast material. The identification and quantification of these elements can be used to diagnose several diseases.


Tube Voltage Hardware Effort Layer Detector Lower Energy Spectrum Tungsten Anode 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Department of Clinical RadiologyUniversity of Munich, Grosshadern HospitalMunichGermany
  2. 2.Institute of Medical PhysicsUniversity of ErlangenErlangenGermany

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