磁共振成像系统中梯度线圈设计的一种新的长度约束方案

A new length constraint method for MRI gradient coil design

目的 针对磁共振成像系统中长度约束的梯度线圈设计 ,寻求一种新的方案 ,使其能代替原有的方法 ,并且可以设计用于头部成像的不对称短线圈。方法 本文在目标场方法的基础上 ,引入了流函数约束条件 ,从而提出了流函数约束方案。并在该方案的基础上提出了一种简单的不对称短梯度线圈设计方案。结果 文中分别对直径 3 2cm ,长径比 1.5∶1的对称和不对称横向梯度线圈进行了仿真设计 ,结果显示了该方案的有效性。结论 文中比较了对称和不对称线圈梯度均匀区的位置 ,结果显示后一种线圈适合头部成像而前一种不适合。

Objective To find a new method to control the length of the MRI gradient coil.The new method can replace the previous ones and is capable of designing short asymmetrical coil which is applicable for head imaging.Methods This work presents a stream function constraint method in which stream function is added to target field method as a constraint condition. On the basis of this,a simple method for short asymmetrical coil is presented.Results The method has been implemented on computer and applied to the designs of 32 cm diameter,1.5∶1(length∶diameter),symmetrical and asymmetrical transverse gradient coils respectively.The results manifest the efficiency of the method on length control of coils of two types.Conclusion The contrast between position of ROU(region of uniformity) of symmetrical coil and that of asymmetrical coil demonstrates that the later is suitable for head imaging while the former is not.