We describe a new method of positioning techniques in this paper. The positioning technique is important to obtain an accurate diagnostic information in radiography. As X-ray films are usually used in radiography, the development of the films becomes necessary. It is desirable to perform the positioning accurately and to confirm the results of the positioning in short time. In this study, we construct an image database which is related to the positioning image of the phantom and its radiographic image. We develop a system which displays the radiographic image by detecting the position of phantom in real time. Furthermore, we use the V-filter to improve the image quality of radiographic images. The V-filter is effective in extracting the region of interesting accurately. It is expected that our method is useful for acquiring of the positioning techniques.