Dose reduction technique in diagnostic X-ray computed tomography by use of 6-channel multileaf collimators.

Recently, region-setting computed tomography (CT) has been studied as a region of interest imaging method. This technique can strongly reduce the radiation dose by limiting the irradiation field. Although mathematical studies have been performed for reduction of the truncation artifact, no experimental studies have been performed so far. In this study, we developed a three-dimensional region-setting CT system and evaluated its imaging properties. As an experimental system, we developed an X-ray CT system with multileaf collimators. In this system, truncated projection data can be captured by limiting of the radiation field. In addition, a truncated projection data correction was performed. Finally, image reconstruction was performed by use of the Feldkamp-Davis-Kress algorithm. In the experiments, the line profiles and the image quality of the reconstructed images were evaluated. The results suggested that the image quality of the proposed method is comparable to that of the original method. Furthermore, we confirmed that the radiation dose was reduced when this system was used. These results indicate that a 3D region-setting CT system using 6-channel multileaf collimators can reduce the radiation dose without in causing a degradation of image quality.