title: A circular test pattern for evaluating x-ray tube focal spots.
abstract: The design and use of a circular x-ray resolution test pattern is presented. This pattern is shown to yield equivalent focal spot dimensions equal to those obtained with the more commonly used star pattern. The advantage of using the circular pattern is that it obviates the necessity of positioning the pattern strictly along the x-ray beam central axis. A major source of experimental error in making focal spot measurements is therefore circumvented, especially in the case of x-ray tubes with a small target angle.
mesh_terms: D008433:Mathematics; D010363:Pattern Recognition, Automated; D011856:Radiographic Image Enhancement; D011859:Radiography / Q000295:instrumentation*; D013679:Technology, Radiologic