<International Circulation>: What are the differences between microSPECT and microPET?

  《国际循环》：microSPECT和microPET有什么区别？

    Dr Sinusas:  One of the problems with microPET with regard to small animal imaging is that there are some inherent limitations with the physics of coincidence detection that involve variation in the angle of the 180 degree separation of the two 511 keV photons. There are also different positron ranges in PET tracers so if they have a higher energy positron， they will migrate before they annihilate and that migration， depending on the PET tracer， can be as much as a centimeter. Even though you can detect the coincidence with high precision， you don’t know where that positron actually originated. That is a limitation with SPECT. In clinical imaging， we are operating in ranges where that isn’t as critical.

    Sinusas博士：对于小动物成像，microPET的一个问题是它在物理学上的重合检测，包括两个511KeV光子在180度夹角的变化的固有局限性。同样在PET示踪剂上有也有不同的正电子范围。如果有较高能量的正电子，在其湮灭之前会发生迁移，根据示踪剂显示，这种迁移会高达1厘米。即使能够检测精度高的重合，也不能确定正电子的真正起源。这是SPECT的局限性，在临床成像时，我们尽量在非至关重要的区域进行操作。