Interventional dual-energy imaging-Feasibility of rapid kV-switching on a C-arm CT system

3D slice of 3D reconstruction of 50% undersampled constant scan of 81 kV with measured ROIs (C 160, W 2000 HU). Arrowhead: contrasted vessel, double arrowhead: dense bone, dashed arrow: soft tissue and normal arrow: bone marrow. Correlation of HU values measured in the ROIs in the kV-switching and in their respective 50% undersampled constant scans (R2 > 0.99).

In the last decade, dual-energy imaging in conventional CT has grown in clinical use. This technique allows the differentiation of materials and tissue based on differential absorption of varying x-ray photon energies. For example, iodine, a commonly used vascular contrast agent, shows sharply decreasing attenuation with increasing x-ray energy. This spectral response is different than that of soft tissue which shows more constant attenuation.

In this work, the hypothesis that fast kV-switching dual-energy imaging is possible with an interventional angiography system using only one sweep of the C-arm is investigated. The system is equipped with one x-ray tube and can be used to generate images at different x-ray energies by switching the x-ray tube voltage rapidly from pulse to pulse. To date, there is no clinically available angiographic C-arm system available, allowing dual-energy imaging during a single rotational 3D acquisition. In a first experiment, tube voltage measurements were performed to prove the concept of kV-switching with the C-arm system and to measure any instability resulting from rapidly switching the tube voltage. A fast kV-switching protocol was used to image an electron density phantom with different iodine concentrations, and a first in vivo study was carried out.

Müller K, Datta S, Ahmad M, Choi J-H, Moore T, Pung L, Niebler C, Gold G E, Maier A, Fahrig R. Interventional dual-energy imaging-Feasibility of rapid kV-switching on a C-arm CT system. Medical Physics 43 (10), pp 5537-5546, 2016 September 20.