Simultaneous multi-head calibration for pinhole SPECT
Simultaneous multi-head calibration for pinhole SPECT
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DOI：
10.1109/tns.2005.862978
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发表时间：
2006-02-01
影响因子：
1.8
通讯作者：
Jaszczak, RJ
中科院分区：
文献类型：
--
作者：
Metzler, SD;Jaszczak, RJ
针孔准直被用作放大几何结构，以克服SPECT中使用的伽马相机的分辨率限制。它对孔径相对于旋转轴的机械位置非常敏感。它还对孔的轴向位置敏感。当使用一个摄像头时，不存在用于确定轴向机械移位的固有参考点。然而，当使用多个头部时，轴向原点可以被定义为第一孔的中心。其他孔可以相对于第一孔测量。本文提出了一种在所有测头的视场中用一个点源同时标定多个测头的方法。机架旋转360度。使用最大似然法将质心拟合到描述轴向和横轴几何形状的方程。点源的三个坐标是沿着轴向和横轴方向上的机械和电子位移确定的;第一孔径的轴向机械位移根据定义被设置为零。多头校准的另一个优点是对点源的位置进行了进一步的约束。我们将校准信息应用于具有1.6 mm磁盘的亚微盘体模。
Pinhole collimation is used as a magnifying geometry to overcome the resolution constraints of the gamma cameras used in SPECT. It is very sensitive to the mechanical position of the aperture relative to the axis of rotation. It is also sensitive to the axial position of the aperture. When one camera head is used, there is no intrinsic reference point for determining the axial mechanical shift. However, when multiple heads are used, the axial origin can be defined as the center of the first aperture. The other apertures can be measured relative to the first. A procedure has been developed for simultaneously calibrating multiple heads by using a single point source in the field of view of all heads. The gantry is rotated through 360 degrees. The centroids are fit using a maximum-likelihood method to an equation that describes the axial and transaxial geometry. The three coordinates of the point source are determined along with the mechanical and electronic shifts in the axial and transaxial directions; the axial mechanical shift of the first aperture is set to zero by definition. Another advantage of multi-head calibration is that a further constraint on the position of the point source is made. We apply the calibration information to a sub-micro disk phantom with 1.6 mm disks.