CT of the brain is generally considered necessary when the following symptoms are present: 1. headache, regardless of the cause of the headache, if the headache is severe and lasts for a long time, it is recommended to do a CT of the head, which may be caused by cerebral hemorrhage or cerebral infarction, intracranial tumor, skull fracture, intracranial hematoma, etc., all of which can cause head pain and can be identified by CT. 2. patients who are often dizzy can also do it. 3. Patients with limb dysfunction, speech dysfunction, unstable walking, easy to fall, and limb hemianesthesia can have head CT, which can identify cerebrovascular diseases, such as cerebral infarction, or cerebral hemorrhage in some patients.