According to the principle of the dynamic computed tomography, stable xenon computed tomography allows measurement of the increase in density caused by xenon in the brain tissue. During a period of about 4 min a patient inhales a mixture of xenon (33%) and oxygen. By means of a special software, this method can be used to calculate flowmaps and to determine the local cerebral blood flow in a 1 cm x 1 cm areal. Stable xenon computed tomography is used mainly for cerebral blood flow measurements in patients with cerebrovascular diseases and also allows calculation of cerebral reserve capacity following stimulation of blood flow by the carboanhydrase inhibitor acetazolamide (Diamox).