What are the determining factors for image quality?
Image quality is determined by two variables: image resolution and image contrast. Image resolution describes the detail an image holds. It quantifies how close lines can be to each other and still be visibly resolved. It is defined in terms of periodically recurring lines, the “horizontal lines of resolution”, which is the number of alternating lines that can be reproduced in an X-ray image and all be seen distinctly. For high magnifications, such as 100x or higher, resolution equals focal spot diameter divided by two. (Feature recognition, that means the size of the smallest, visibly resolved object, is defined as one third of the focal spot diameter). For lower magnifications (< 10 times), the detector’s effective pixel width is the decisive factor. The image contrast is dependant on the tube current and, above all, the signal-to-noise ratio on the detector output screen. For highest image quality, choose an X-ray system that is supplied with an X-ray tube offering a focal spot that
