@article{ZiemonsHeinrichsStreunetal.2004,
  author    = {Ziemons, Karl and Heinrichs, U. and Streun, M. and Pietrzyk, U.},
  title     = {Validation of GEANT3 simulation studies with a dual-head PMT ClearPET™ prototype},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  issn      = {1082-3654},
  pages     = {3053 -- 3056},
  year      = {2004},
  abstract  = {The ClearPET™ project is proposed by working groups of the Crystal Clear Collaboration (CCC) to develop a 2nd generation high performance small animal positron emission tomograph (PET). High sensitivity and high spatial resolution is foreseen for the ClearPET™ camera by using a phoswich arrangement combining mixed lutetium yttrium aluminum perovskite (LuYAP:Ce) and lutetium oxyorthosilicate (LSO) scintillating crystals. Design optimizations for the first photomultiplier tube (PMT) based ClearPET camera are done with a Monte-Carlo simulation package implemented on GEANT3 (CERN, Geneva, Switzerland). A dual-head prototype has been built to test the frontend electronics and was used to validate the implementation of the GEANT3 simulation tool. Multiple simulations were performed following the experimental protocols to measure the intrinsic resolution and the sensitivity profile in axial and radial direction. Including a mean energy resolution of about 27.0\% the simulated intrinsic resolution is about (1.41±0.11)mm compared to the measured of (1.48±0.06)mm. The simulated sensitivity profiles show a mean square deviation of 12.6\% in axial direction and 3.6\% in radial direction. Satisfactorily these results are representative for all designs and confirm the scanner geometry.},
  language  = {en}
}
@article{HeinrichsPietrzykZiemons2003,
  author    = {Heinrichs, U. and Pietrzyk, U. and Ziemons, Karl},
  title     = {Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {50},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {5},
  isbn      = {0018-9499},
  pages     = {1428 -- 1432},
  year      = {2003},
  abstract  = {Within the Crystal Clear Collaboration (CCC), four centers are developing second generation high performance small animal positron emission tomography (PET) scanners for different kinds of animals and medical applications. The first prototypes are photomultiplier tube (PMT)-based systems including depth of interaction (DOI) detection by using a phoswich layer of lutetium oxyorthosilicate (LSO) and lutetium yttrium aluminum perovskite (LuYAP). The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in fields of view (FOVs) caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN, Geneva, Switzerland) was used.},
  language  = {en}
}
@article{HeinrichsPietrzykZiemons2003,
  author    = {Heinrichs, U. and Pietrzyk, U. and Ziemons, Karl},
  title     = {Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3},
  series = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {682 -- 686},
  year      = {2003},
  abstract  = {Within the Crystal Clear Collaboration four centres are developing 2nd generation high performance small animal PET scanners for different kinds of animals and medical applications. The first prototypes are PMT-based systems including depth of interaction (DOI) detection by using a phoswich layer of LSO and LuYAP. The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in FOVs caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN) was used. The simulations have shown that all PMT designs with one-to-one coupling of crystals have a very nonlinear axial sensitivity profile. By shifting every other PMT 1/4 of a PMT length in axial direction the sampling of the FOVs became more homogeneous. At an energy threshold of 350keV the regression coefficient increases from 0.818 for the non-shifted to 0.993 for the shifted design. Simulations of a point source centred in the FOV (threshold: 350keV) resulted in sensitivities of 4.2\% for a 4×20PMT (LSO/LuYAP a 10mm) and 3.8\% for a 4×16PMT (LSO/LuYAP a 8mm) ring design. The 3D-MLEM reconstruction of a point source shows the enormous improvement of resolution using a crystal double layer with DOI (3.1mm at 40mm from CFOV) instead of a 20mm single layer (11.9mm).},
  language  = {en}
}