The effect of x-ray tube voltage modulation to quality of perfusion images in cone beam C-arm CT

Abstract

Dynamic dose modulation techniques are applied in CT acquisitions to ensure optimal working conditions of the detector unit and to reduce overall radiation exposure of the patient. In C-arm CT systems, large variations in the desired irradiation may require tube voltage modulation (TVM). Recent studies showed that TVM does not affect the quality of perfusion images obtained by clinical CT. Here, we investigate the impact of TVM in a C-arm cone beam CT perfusion imaging setting. We conduct a simulation study based on a real perfusion acquisition (incl. tube modulation) to directly compare results from acquisitions with and without modulation. Using two different reconstruction techniques, we analyze the influence of TVM on the extracted perfusion parameters and quantify the similarity by their correlation coefficients. Our results demonstrate that high correlation (r < 0.99) between the results with and without TVM are achieved for all perfusion parameters using a straightforward and model-based reconstruction technique. These findings suggest that dose modulation techniques, incl. TVM, can be used in C-arm CT perfusion scans without the need for additional correction methods to retain image quality of constant voltage scans.