2 Tome is Greek for slice. Left is shown at right. Other standard planes of view are coronal and sagittal . Each pixel represents brain tissue which is about 1 mm.
Pixel intensity represents an average from tissue within the voxel.
A beam of x-rays is shot straight through the brain. As it comes out the other side, the beam is blunted slightly because it has hit dense living tissues on the way through. X-ray detectors positioned around the circumference of the scanner collect attenuation readings from multiple angles. A computerized algorithm reconstructs an image of each slice. The strength of the transmitted energy is proportional to the number of protons in the tissue.