The influence of image quality characteristics on the accuracy of vessel measurement was investigated using simple vascular models, the comparison of the profile curve of the cross section of the vascular models and physical image quality characteristics such as modulation transfer function (MTF), Wiener spectrum (WS) and contrast, with changing scan conditions. The profile curves in the section part that greatly influences the measurement accuracy of the vessel diameter has changed by x-ray tube voltage. The noise has increased evenly in all frequency band regions at the same time though the contrast rose in 2 and 4 mm vascular models. The change was not seen in MTF. It can be said that the decision of the scan parameters that raises the contrast and decreases the noise will improve the measurement accuracy of the vessel diameter.