2015 年 71 巻 3 号 p. 230-236
This study aimed to reduce contrast medium dose without reducing the diagnostic capability of computed tomography (CT) angiography of the head. We evaluated the advanced statistical iterative reconstruction (ASiR) settings to adjust to low tube voltage CT. A syringe phantom was constructed using dilute contrast medium and was imaged at tube voltages of 80–120 kV. The iodine volumes, CT values, and image noise were measured in these images. The noise-power spectrum and modulation transfer function were measured from quality assurance phantom images that had been obtained using the tube voltage selected after considering the image noise results as described above and reconstructed using different ASiR rate settings and convolution kernels. Our results suggested that imaging at 100 kV could reduce the contrast medium dose by 14%, compared with imaging at 120 kV, and that the resulting image quality could equal that of conventional imaging by performing reconstruction at a 40% ASiR rate and detail kernel.
