We present the results of testing a previously presented algorithm for three-dimensional image reconstruction that uses all gamma-ray coincidence events detected by a PET volumeimaging scanner. By using two iterations of an analytic filterbackprojection method, the algorithm is not constrained by the requirement of a spatially invariant detector point spread function, which limits normal analytic techniques. Removing this constraint allows the incorporation of all detected events, regardless of orientation, which improves the statistical quality of the final reconstructed image.

No abstract

No abstract

No abstract

We have developed a simulation to model position encoding multicrystal detectors for positron emission tomography. The simulation is designed to treat the interactions of energetic photons in a scintillator, the geometry of the multicrystal array, as well as the propagation and detection of individual scintillation photons. The simulation is tested with a model of the EXACT HR PLUS block detector manufactured by Siemens-CTI. Position and energy responses derived from the simulation are compared to measured ones. Line-spread-functions, for four columns of crystals, are reproduced with an accuracy of 50.5 111111. The crysta~-~y-crystal photopeak pulse heights and FWHM's are also predicted within a range of f14%, and ?i %, respectively.

No abstract

No abstract

The "He(p, 2p) H reaction has been studied at 250, 350, and 500 MeV using coplanar symmetric and asymmetric geometries. The data are presented as energy-sharing spectra, coplanar symmetric angular distributions, and quasifree angular distributions. A comparison with distorted wave impulse approximation calculations indicates reasonable agreement for small recoil momenta (q & 150 MeV jc). For larger recoil momenta, the distorted-wave impulse approximation calculations increasingly underestimate the data.The discrepancies are substantially reduced by inclusion of a spin-orbit term in the optical potential used to generate the distorted waves. Improvements of the single particle wave function for the struck nucleon influence the calculations to a lesser degree. The remaining discrepancies at large recoil momenta may, in part, be ascribed to multiple scattering effects and exchange processes not included in the standard distorted-wave impulse approximation.NUCLEAR REACTIONS He(p, 2p ) H; measured d~/(d Q3d Q~dT3), 250, 350, 500 MeV, energy sharing spectra, coplanar symmetric angular distributions, quasifree angular distributions; comparison with DWIA calculations.