Author/Authors :
Bنck، نويسنده , , T and Cederkنll، نويسنده , , J and Cederwall، نويسنده , , B and Johnson، نويسنده , , A and Kerek، نويسنده , , A and Klamra، نويسنده , , W and van der Marel، نويسنده , , J and Molnلr، نويسنده , , J and Novلk، نويسنده , , D and Sohler، نويسنده , , D and Steén، نويسنده , , M and Uhlén، نويسنده , , P، نويسنده ,
Abstract :
A TOF-PET system has been designed and constructed for educational purposes. The aim of this system is to demonstrate the possibilities of positron emission tomography in general and the time-of-flight method in particular to the students of various courses at the Royal Institute of Technology, Stockholm, Sweden. The set-up consists of 48 small BaF2 crystals coupled to fast photomultipliers placed in a ring geometry. The signals of the photomultipliers are fed into fast constant fraction discriminators (CFD). The outputs of these are directed to a specially designed logic VME unit, which combines the CFD signals of 6 neighbouring channels to one signal by adding a different delay to each channel. The logic circuitry produces a prompt pulse for each event that serves as the start pulse for the 8-channel fast TDC. The delayed pulses act as the stop pulses for the TDC. In a computer, the measured times are converted into information about which the photomultipliers fired with the difference in the time of flight. The set-up is described and the results are presented.
