抄録
It is necessary to remove artifacts caused by metal in the mouth in order to make a living body model from three-dimensional CT images. This has become a problem that cannot be ignored, because in recent years CT scanners have become more efficient and the number of images output has increased greatly. So, to assist this work, we examined a method of automatically detecting of artifacts on the basis of a change of CT value. To catch artifacts, we examined 11,991 CT images of 147 samples taken in the past, and traced changes of range 1 （CT value from －1024 to －961）, range 2 （CT value from －960 to －897） and range 17 （CT value from 0 to 63）.
As a result, we could automatically detect more than 70 % of slice images which had artifacts.
