Dosimetry of dual-energy CT for the detection of acute-stage cerebral infarction: A phantom study

We established a method for image-based diagnosis of cerebral stroke by developing a phantom that could visualize cerebral stroke using X-ray CT imaging, while evaluating the imaging conditions. We recently improved the contrast of acute-stage cerebral infarction using virtual monochromatic images obtained by dual-energy CT. We measured radiation doses using the newly developed phantom while assessing its potential clinical application. In this study, the tube voltages with a thin (Sn) filter were 80 kV/Sn 140 kV, 100 kV/Sn140 kV, and 140 kV/80 kV; the tube current time products were 400, 600, and 800 mAs; and the scanning range was 120 mm from the orbitomeatal line to the parietal region. The dose was measured three times using TLD, and the absorbed dose was obtained from the average. Compared with 120 kV, the absorbed dose could be reduced by approximately 47 % at 80 kV/Sn 140 kV, approximately 30 % at 100 kV/Sn 140 kV, and approximately 22 % at 140 kV/80 kV, when the tube current time product was 600 mAs. Our dose measurement for visualizing acute-stage cerebral infarction revealed that the dose could be reduced with dual-energy CT compared with CT at 120 kV.