Characteristics of a newly developed dentomaxillofacial X-ray cone beam CT scanner (CB MercuRay™):: system configuration and physical properties

Objective: The purpose of this paper is to present the system configuration and physical properties of a new dentomaxillofacial X-ray cone beam CT system (CB MercuRay(TM)) being developed. Methods: The system consists of an image intensifier and a cone beam X-ray source. There are two different models of this system, each with a different size image intensifier, 9" or 12". Each system has three field of view (FOV) modes. The 12" system has facial (F), panoramic (P) and implant (1) FOV modes. The 9" system has P, I and dental (D) modes. Images produced by these systems consist of 5 12 X 512 X 512 isotropic voxels. Physical properties such as resolution, noise and distortion of the images were evaluated in this study. Modulation transfer function (MTF) was measured using Boone's method. Image noise was measured as the standard deviation of the CT value in water. Circularity of the axial images yielded by the two models was measured using an 8 mm diameter acrylic pipe phantom. Results: The resolving power at a MTF of 0.1 in the D mode was over 2.01p mm(-1), suggesting that this system yields images of high resolution. The standard deviation of the CT value in water was approximately 80, which is thought to be greater than that of conventional CT. The circularity of images of the pipe phantom was 99% of the ideal value. Conclusion: This study shows that our newly developed cone beam CT system produces high resolution three-dimensional volumetric images that will be useful for the examination of dentomaxillofacial disorders.