Why does increasing source–image distance (SID) improve spatial resolution? Increasing the source–image distance (SID) improves spatial resolution because it reduces geometric unsharpness and magnification. As the X-ray source is moved further from the patient, the X-ray beam becomes less divergent…
What is geometric unsharpness? Geometric unsharpness refers to image blur caused by the finite size of the X-ray focal spot and the geometry of the imaging setup. Because X-rays originate from a small area rather than a perfect point source,…
Why does focal spot size affect image sharpness? Focal spot size affects image sharpness because X-rays originate from a finite area on the anode, not from a perfect point source. When the focal spot is larger, photons originate from a…
What determines spatial resolution in radiography? Spatial resolution in radiography describes the ability of an imaging system to distinguish small, closely spaced structures as separate objects. High spatial resolution allows fine anatomical detail to be seen clearly, while poor spatial…
What is spatial resolution in radiography? Spatial resolution refers to the ability of an imaging system to distinguish two closely spaced structures as separate objects. It describes how clearly fine anatomical detail can be visualised in a radiographic image. Spatial…
What determines image contrast in digital radiography? Image contrast in digital radiography is determined primarily by differences in X-ray attenuation between tissues, which depend on photon energy, tissue composition, and thickness. These differences produce variations in the number of photons…
What is quantum noise (quantum mottle)? Quantum noise, also called quantum mottle, is the random variation in image intensity caused by the statistical nature of X-ray photon detection. It occurs because the number of photons detected in different regions of…
What is signal-to-noise ratio (SNR) in radiography? Signal-to-noise ratio (SNR) describes the relationship between the useful image signal and the random noise present in the image. It reflects how clearly anatomical structures can be distinguished from background fluctuations. Signal-to-noise ratio…
What is detective quantum efficiency (DQE)? This is a brief, non technical, overview. Detective quantum efficiency (DQE) describes how efficiently an imaging detector converts incoming X-ray photons into a useful image signal while preserving image quality. It reflects how well…
What is a photoconductor? A photoconductor is a material that converts absorbed X-ray photons directly into electrical charge. When an X-ray photon is absorbed within the material, it generates mobile charge carriers that can be collected to form an electrical…