Cerebral arteriovenous malformation (AVM) is also known as cerebral hemangioma, angiomatous malformation, cerebral arteriovenous fistula and so on. The lack of capillaries between cerebral arteries and cerebral veins at the lesion site results in direct communication between arteries and veins, forming a short circuit between cerebral arteries and veins, and resulting in a series of pathological and cerebral hemodynamic changes, resulting in recurrent intracerebral spontaneous hemorrhage, progressive neurological dysfunction, convulsions and other clinical manifestations. Also, cerebral arteriovenous malformation is one of the most common causes of subarachnoid hemorrhage. Clinical manifestations of arteriovenous malformation 1.Clinical manifestations: ① bleeding; ② epilepsy; ③ progressive neurological dysfunction; ④ headache; ⑤ other symptoms. 2, gamma knife treatment positioning ① general angiography positioning: this is the most classic positioning method of brain arteriovenous malformation gamma knife treatment. Since the early introduction of the Gamma Knife was used for the positioning of cerebral arteriovenous malformations, in most Gamma Knife treatment centers still use this method. The advantage of this method is that it does not require a lot of imaging equipment for localization, and it can be done only with the availability of an X-ray machine, and it is accurate. When combined with the use of rapid serial filming methods, vascular perfusion can be obtained for different periods of time so that the blood supplying arteries, malformed vascular nests and draining veins can be distinguished. However, the greatest disadvantage of plain angiography is that it only provides two-dimensional imaging information and cannot yet clearly express the three-dimensional configuration of irregular or complex vascular malformations. In addition, compared with digital subtraction angiography, the image resolution of plain angiography is not yet high, and it is susceptible to cranial and positioning frame artifacts. In particular, for cerebral arteriovenous malformations located at the skull base and posterior cranial sulcus, plain angiography sometimes does not show the lesions clearly enough. The advent of high-resolution angiography in recent years has partially compensated for this deficiency. ②Digital subtraction angiography (DSA) localization: Digital subtraction angiography localization technique has only been applied in recent years for the localization of cerebral arteriovenous malformations before gamma knife treatment. The reason is that DSA images without special correction, although the display of the vascular nest of cerebral arteriovenous malformations is clearer than ordinary angiography, and is not disturbed by artifacts such as skull, but the accuracy of localization is not high due to the existence of obvious image aberrations. Therefore, it has affected its clinical application. Since 1995, special computer programs and methods for correcting DSA image aberrations have been available. Users can obtain corrected images by simply installing this special program in the DSA machine. This image overcomes the shortcomings of conventional DSA image aberrations while maintaining the good resolution of DSA images compared to normal angiography, and is therefore very popular among clinical users. In addition to clear image display, another feature of DSA positioning technology is that there is greater flexibility in the timing and number of image samples taken during imaging. Therefore, it is easier to capture the image when the nest of malformed vessels is intact and the draining vein is just appearing as the best positioning phase. CT localization: CT shows most of the arteriovenous malformations clearly, especially the enhanced CT scans, which usually show the arteriovenous malformations in a mass-like enhancement, and sometimes also the twisted blood supply arteries and draining veins. In addition, CT can also show the structures of the tissue adjacent to the AVM and the hematoma cavity formed by a history of previous hemorrhage. Compared with angiographic localization, CT localization provides a better three-dimensional morphologic representation of AVMs and is more accurate. However, plain CT localization also has some limitations. For example, it is often difficult to achieve a high degree of selectivity in the display of malformed vessel nests, and it is sometimes difficult to identify the blood supply artery, malformed vessel nests and draining veins on the acquired images, which makes it more difficult to determine the extent of the target area. In addition, CT localization images are also susceptible to influence from the skull or foreign bodies. As a result, CT localization of AVMs located at the skull base and posterior cranial recesses sometimes does not provide a satisfactory image display. The advent of fast CT has partially compensated for the deficiencies of general CT in AVM localization. By using special software, with the use of high-pressure injector, fast CT can capture images of the contrast agent passing through different phases of cerebral vessels (malformed vessels) and reshape the three-dimensional spatial morphology of AVMs (CT angiography, CTA) by image reconstruction techniques, which provides good conditions for accurate determination of the target area range. Only fast CT is expensive and difficult to be popularized in China, and its application is limited.