Effect of the Software Coincidence Timing Window in Time-of-Flight Assisted Positron Emission Tomography

The effect of the software coincidence timing window (SCW) has been studied and demonstrated experimentally using Super PETT I, a time-of-flight (TOF) assisted positron emission tomograph. This method utilizes the TOF information to eliminate unwanted random and scattered coincidence events outside of a region of interest. The effect is substantial for high count rate studies, and can dramatically improve the noise contribution from measured attenuation factors. The effective coincidence window is reduced to 3.3 nsec for reconstructions of the field of view, and reduced to only 2 nsec for measurement of the attenuation factors.