The use of Dual-Energy in Computed Tomography

A dual-energy CT using fast kV-switching has recently been installed at the Queen Silvia Children’s Hospital in Gothenburg Sweden. This type of CT has never before been installed for clinical purposes at a children’s hospital. This study aimed to get an understanding of how the dual-energy technique works and what it can be used for. This first study, which found out some of the properties of the dual-energy technique would be used to lay the foundation of the knowledge of how to use this technique on children. This study confirmed that the dual-energy ability to create monochromatic images, could reduce the metal artefacts from a double hip-joint-prosthesis. The ability to measure mass density, CT-values at various monochromatic energies was investigated. The metal artefact reduction algorithm of this CT was found to improve the measured CT-value of water with an Aluminium rod present in the image. It was hard to find a relation of low contrast visibility against dose, because the tube current could not be changed. The visibility of a dual-energy scan reconstructed at the approximate mean photon energy of a 120 kVp spectrum showed not to be better than a polychromatic scan at 120 kVp. The results from this study showed though that the accuracy of measuring CT-values to be better using dual-energy. A conclusion was that the dual-energy technique could have a clinical application. The dose was though sometimes ten times higher compared to a normal CT-scan on a child. The doctor should take this into consideration, when deciding the type of scan technique.