All computed tomography (CT) scanners use X-rays to produce anatomical images; however, there have been enormous developments over the years in how this is achieved. The broad principle of CT scanning has remained unchanged over the years, but technological advances have been accompanied by changes in the algorithms used. Intravenous contrast used in CT is an iodine-based substance similar to that used for intravenous urograms (IVUs) and numerous other radiological procedures such as angiography. CT scans of the head are usually presented on brain windows, but are also frequently presented on bone windows, particularly in the context of trauma. After the CT scan, the patient should be kept intubated and ventilated, and returned to an intensive therapy area while the case is discussed with the local neurosurgeons. An entirely normal unenhanced CT scan of the brain is not sufficient to completely exclude intracranial metastatic disease.