Target Delineation in Radiosurgery for Cerebral Arteriovenous Malformations
Target Delineation in Radiosurgery for Cerebral Arteriovenous Malformations
复制标题
脑动静脉畸形放射外科靶区勾画
作者：
Wan;B. Nordell;B. Karlsson;Michael Söderman;M. Lindqvist;Kaj Ericson;A. Franck;Ingmar Lax;Christer Lindquist
本文对6例动静脉畸形（AVM）患者进行了研究，探讨了在磁共振图像上勾画动静脉畸形的可行性，并比较了在不同图像上勾画动静脉畸形的体积。常规立体定向血管成像，立体定向磁共振成像和磁共振血管成像使用几种不同的脉冲序列放射手术前获得。根据常规立体定向血管造影制定治疗方案。然后将这些计划转移到单独的剂量计划计算机上，该计算机显示带有叠加等剂量线的核磁共振图像。通过这些磁共振图像测量AVM和脑组织的辐射体积。最后，如果治疗计划是根据MR图像而不是传统的立体定向血管造影制定的，则对适当治疗AVM所需的辐射量进行评估。基于各种脉冲序列信息的整合，可以在立体MR图像上圈定中、大尺寸AVM nidi。在常规立体定向血管造影上发现的AVM nidi的估计体积比在立体定向MR图像上发现的要大。因此，基于传统立体定向血管造影的剂量计划将导致相同靶剂量下更高的脑整体剂量。通过使用可靠的MR信息，预期可以减少脑暴露于辐射的体积，从而最大限度地减少立体定向放射手术对AVM的不良影响。
A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.