Transcranial Doppler and cranial CT are not the same in nature. Transcranial Doppler is mainly to check the blood vessels and blood flow in the brain to see how fast or slow the blood flow is, and whether there is any blockage or thrombosis in the blood vessels. Cranial CT generally looks at whether there are substantial changes inside the brain, and in the case of cranial CTA, also known as angiography, the blood flow of the blood vessels can be seen. If the patient is dizzy, to determine whether there is a blockage of blood vessels or blood flow, transcranial Doppler can be performed. To determine whether the patient has lesions inside the skull, such as cerebral infarction, cerebral hemorrhage or brain tumor, a CT of the brain must be performed to see clearly.