2016 年 72 巻 8 号 p. 657-666
The purpose of this study was to investigate the effect of the position in XYZ directions and acquisition parameters on the basic image qualities of for cone beam computed tomography (CBCT) in an angiography system with flat panel detector. The resolution property (modulation transfer function: MTF) and the noise property (Wiener spectrum: WS) of CBCT images in X-Y plane were measured with different acquisition parameters (scan matrix number and projection number) and the effect of the position in XYZ directions. The MTFs with 1024×1024 matrix were higher than those of 512×512 matrix and decreased in the peripheral areas due to the reduction of projection number. The highest and the lowest MTFs were measured at the X-ray tube side and on the detector side of the position in X-Y plane, respectively. The WS-doubled projection number showed about 50% lesser noise level. There were differences in the Wiener spectra (WS) at the position in XYZ directions. We conclude that the resolution and the noise property of CBCT image in X-Y plane showed dependences on the position in XYZ directions and acquisition parameters of the CBCT.
