Radiation dose is cumulative in the radiosensitive organs. In neuroradiology the organ of particular interest is the eye. There is an immutable physical relationship between spatial resolution, signal-to-noise ratio (i.e., density discrimination), and dose: Dose alpha (formula: see text). Optimal imaging conditions require a compromise between these three factors. The factors concerned in the effective utilisation of dose are discussed and the various compromises considered. Radiation dose measurements are given for a wide variety of neuroradiological procedures, including CT employing the EMI CT1010 and CT5005.