Rotating CTA scan of healthy human kidneys and their associated blood vessels. The kidneys are supplied by blood by the renal arteries, which branch directly from the descending abdominal aorta (down centre). The kidneys filter waste products from the blood and pass it to the bladder as urine. CTA (computed tomography angiography) scans use X-rays to create slice images of tissues, which are compiled into 3D models. The angiography aspect uses a radio-opaque contrast medium injected into the blood vessels to allow them to be clearly seen.