Stones of different composition have different probabilities of occurrence and vary in density and morphology: a. Oxalate-based stones are dense, mostly round or star-shaped, and are the most common stones; b. Phosphate-based stones are often large and dense, and can be antler-shaped when they occur in the pelvis and calyces, and small stones are round or sandy; c. Uric acid-based stones are often small, and simple urate stones are less dense; d. Cysteamine-based stones are less common and can be multiple and less dense. d. Cystathione-dominated stones are less common, can be multiple and have a lower density. Stones of different composition have different densities and are classified as positive stones (stones that can be visualized on KUB plain films) or negative stones (stones that cannot be visualized on KUB plain films) according to whether they are visualized on KUB plain films. When urinary stones are suspected clinically, KUB plain film or ultrasound is used as the initial investigation method, and when it is difficult to confirm the diagnosis, urography or CT examination is required. Kidney stones are the first among urinary stones, more in men than in women, and often unilateral. The typical clinical symptoms are pain and hematuria, and the X-ray shows single or multiple high-density shadows of variable size and shape in the kidney area, the larger ones can fill the pelvis and calyces, while the smaller ones are only punctate or nodular. CT scan is able to detect high-density stones in the pelvis and calyces, and some negative stones can also be shown on CT.