The development and construction of a new cylindrical SPECT Anger camera

Summary form only given. A cylindrical SPECT (single photon emission computed tomography) camera with a 18-cm-high and 30-cm-inner-diameter NaI(Tl) scintillator was developed at the University of Stockholm and the Karolinska Hospital. In the present design the crystal is surrounded by 72 2.5-in. hexagonal photomultipliers with front-end windows, shaped to allow a direct and close connection to the cylindrical crystal assembly. The absorption events are sampled by 72 local acquisition units, each consisting of a central tube and its six (in some cases five or three) neighbors, using the signal sum as a first-level trigger. The light distribution into the photomultiplier tubes of the triggered acquisition group and the instantaneous position of the rotating collimator are used to estimate the projected location of the events using a locally optimized position encoding algorithm. The local acquisition units and their supervisors are realized as a hierarchical transputer network. The design parameters were examined and determined after careful measurements and simulations.<>