Computed tomography of the head uses a series of X-rays in a CT scan of the head taken from many different directions; the resulting data is transformed into a series of cross sections of the brain using a computer program. CT images of the head are used to investigate and diagnose brain injuries and other neurological conditions, as well as other conditions involving the skull or sinuses; it used to guide some brain surgery procedures as well. CT scans expose the person getting them to ionizing radiation which has a risk of eventually causing cancer; some people have allergic reactions to contrast agents that are used in some CT procedures. Uses Computed tomography (CT) has become the diagnostic modality of choice for head trauma due to its accuracy, reliability, safety, and wide availability. The changes in microcirculation, impaired auto-regulation, cerebral edema, and axonal injury start as soon as head injury occurs and manifest as clinical, biochemical, and radiological changes. Proper therapeutic management of brain injury is based on correct diagnosis and appreciation of the temporal course of the disease process. CT scan detects and precisely localizes the intracranial hematomas, cerebral contusions, edema and foreign bodies. Even in emergency situations, when a head injury is minor as determined by a physician's evaluation and based on established guidelines, CT of the head should be avoided for adults and delayed pending clinical observation in the emergency department for children. Many people visit emergency departments for minor head injuries. CT scans of the head can confirm a diagnosis of skull fracture or brain bleeding, but even in the emergency department, such things are uncommon and not minor injuries, so CT of the head is usually not necessary. Clinical trials have shown the efficacy and safety of using CT of the head in emergency settings only when indicated, which would be at the indication of evidence-based guidelines following the physical examination and a review of the person's history. Concussion is not a routine indication for having brain CT or brain MRI and can be diagnosed by a healthcare provider trained to manage concussions. People with concussions usually do not have relevant abnormalities about which brain imaging could give insight, so brain imaging should not routinely be ordered for people with concussions. If there is concern about a skull fracture, focal neurological symptoms present or worsening symptoms, then CT imaging may be useful. MRI may be