2. Application of Star Test Pattern in the Quality Guaranty of Imaging System

Tranditional radiographic techniques also have important value in X-ray imaging techniques. The inspection of imaging ability of X-ray tube is a important factor. We use star test pattern to measure the size, resolution and expension of effective focal spot. However there is no unanimous opinion about the magnification rate when various sizes of focal spot are measured by means of star test pattern. The magnification rate and the basic principle of magnification technique for different focal spots are discussed in this paper.