CT brain scans. Assortment of coloured computed tomography (CT) scans of the human brain. At top left is the head sectioned in sagittal view; all other scans show the brain in horizontal (axial) section. A rounded brain tumour is revealed (magenta) in some of the brain scans at centre right. CT scanning creates 'slice' images through the body using X-rays. It is useful in detecting brain tumours and cancer.