Closed-bore XMR (CBXMR) systems for aortic valve replacement: x-ray tube imaging performance.
Closed-bore XMR (CBXMR) systems for aortic valve replacement: x-ray tube imaging performance.
复制标题
用于主动脉瓣置换术的闭孔 XMR (CBXMR) 系统：X 射线管成像性能。
DOI：
10.1118/1.3086188
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发表时间：
2009
期刊：
影响因子：
3.8
通讯作者：
Rowlands,JA
中科院分区：
文献类型：
--
作者：
Bracken,JohnA;Komljenovic,Philip;Lillaney,PrasheelV;Fahrig,Rebecca;Rowlands,JA
提出了一种混合闭孔X射线/MRI系统（CBXMR），以提高经皮主动脉瓣置换术的安全性和有效性。在该系统中，X射线C形臂将位于距离1.5 T MRI扫描仪入口约1 m处。CBXMR系统将利用两种模式的互补优势，在无冠状动脉阻塞的情况下将人工生物瓣膜引导并展开到心脏的主动脉瓣环中。构建该系统的一个主要挑战是确保旋转阳极X射线管在MRI边缘磁场环境中正常运行。X射线管中负责产生X射线的电子束可以被边缘场偏转。然而，在磁场中的电子束偏转的临床影响尚未研究。在这里，作者研究了电子束偏转导致的X射线图像中焦斑分辨率、视场偏移和视场截断的变化。作者发现，在X射线C形臂（4 mT）临床位置处作用于X射线管的边缘场中，焦斑尺寸仅增加2%，因此边缘场不会限制X射线系统的分辨率。磁场还导致视野偏移3 mm。必须纠正这种偏移，以避免患者和心导管实验室工作人员受到不必要的初级辐射照射。边缘场太弱，不会导致视场截断。
A hybrid closed‐bore x‐ray/MRI system (CBXMR) is proposed to improve the safety and efficacy of percutaneous aortic valve replacement procedures. In this system, an x‐ray C‐arm will be positioned about 1 m from the entrance of a 1.5 T MRI scanner. The CBXMR system will harness the complementary strengths of both modalities to guide and deploy a bioprosthetic valve into the aortic annulus of the heart without coronary artery obstruction. A major challenge in constructing this system is ensuring proper operation of a rotating‐anode x‐ray tube in the MRI magnetic fringe field environment. The electron beam in the x‐ray tube responsible for producing x rays can be deflected by the fringe field. However, the clinical impact of electron beam deflection in a magnetic field has not yet been studied. Here, the authors investigated changes in focal spot resolving power, field of view shift, and field of view truncation in x‐ray images as a result of electron beam deflection. The authors found that in the fringe field acting on the x‐ray tube at the clinical location for the x‐ray C‐arm (4 mT), focal spot size increased by only 2%, so the fringe field did not limit the resolving power of the x‐ray system. The magnetic field also caused the field of view to shift by 3 mm. This shift must be corrected to avoid unnecessary primary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. The fringe field was too weak to cause field of view truncation.