@article{HeinrichBlumBussmannetal.2002,
  author    = {Heinrich, U. and Blum, A. and Bussmann, N. and Engels, R. and Kemmerling, G. and Weber, S. and Ziemons, Karl},
  title     = {Statistical studies on the light output and energy resolution of small LSO single crystals with different surface treatments combined with various reflector materials},
  series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {486},
  journal   = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {1-2},
  issn      = {0168-9002},
  pages     = {60 -- 66},
  year      = {2002},
  abstract  = {The optimization of light output and energy resolution of scintillators is of special interest for the development of high resolution and high sensitivity PET. The aim of this work is to obtain statistically reliable results concerning optimal surface treatment of scintillation crystals and the selection of reflector material. For this purpose, raw, mechanically polished and etched LSO crystals (size 2×2×10 mm3) were combined with various reflector materials (Teflon tape, Teflon matrix, BaSO4) and exposed to a 22Na source. In order to ensure the statistical reliability of the results, groups of 10 LSO crystals each were measured for all combinations of surface treatment and reflector material. Using no reflector material the light output increased up to 551±35\% by mechanical polishing the surface compared to 100±5\% for raw crystals. Etching the surface increased the light output to 441±29\%. The untreated crystals had an energy resolution of 24.6±4.0\%. By mechanical polishing the surface it was possible to achieve an energy resolution of 13.2±0.8\%, by etching of 14.8±0.7\%. In combination with BaSO4 as reflector material the maximum increase of light output has been established to 932±57\% for mechanically polished and 895±61\% for etched crystals. The combination with BaSO4 also caused the best improvement of the energy resolution up to 11.6±0.2\% for mechanically polished and 12.2±0.3\% for etched crystals. Relating to the light output there was no significant statistical difference between the two surface treatments in combination with BaSO4. In contrast to this, the statistical results of the energy resolution have shown the combination of mechanical polishing and BaSO4 as the optimum.},
  language  = {en}
}
@article{KhodaverdiChatziioannouWeberetal.2005,
  author    = {Khodaverdi, M. and Chatziioannou, A. F. and Weber, S. and Ziemons, Karl and Halling, H. and Pietrzyk, U.},
  title     = {Investigation of different MicroCT scanner configurations by GEANT4 simulations},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {52},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {1},
  isbn      = {0018-9499},
  pages     = {188 -- 192},
  year      = {2005},
  abstract  = {This study has been performed to design the combination of the new ClearPET (ClearPET is a trademark of the Crystal Clear Collaboration), a small animal positron emission tomography (PET) system, with a micro-computed tomography (microCT) scanner. The properties of different microCT systems have been determined by simulations based on GEANT4. We will demonstrate the influence of the detector material and the X-ray spectrum on the obtained contrast. Four different detector materials (selenium, cadmium zinc telluride, cesium iodide and gadolinium oxysulfide) and two X-ray spectra (a molybdenum and a tungsten source) have been considered. The spectra have also been modified by aluminum filters of varying thickness. The contrast between different tissue types (water, air, brain, bone and fat) has been simulated by using a suitable phantom. The results indicate the possibility to improve the image contrast in microCT by an optimized combination of the X-ray source and detector material.},
  language  = {en}
}
@article{KhodaverdiWeberStreunetal.2006,
  author    = {Khodaverdi, M. and Weber, S. and Streun, M. and Parl, C. and Ziemons, Karl},
  title     = {High resolution imaging with ClearPET™ Neuro - first animal images},
  series = {2005 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2005 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  isbn      = {1082-3654},
  pages     = {1641 -- 1644},
  year      = {2006},
  abstract  = {The ClearPET™ Neuro is the first full ring scanner within the Crystal Clear Collaboration (CCC). It consists of 80 detector modules allocated to 20 cassettes. LSO and LuYAP:Ce crystals in phoswich configuration in combination with position sensitive photomultiplier tubes are used to achieve high sensitivity and realize the acquisition of the depth of interaction (DOI) information. The complete system has been tested concerning the mechanical and electronical stability and interplay. Moreover, suitable corrections have been implemented into the reconstruction procedure to ensure high image quality. We present first results which show the successful operation of the ClearPET™ Neuro for artefact free and high resolution small animal imaging. Based on these results during the past few months the ClearPET™ Neuro System has been modified in order to optimize the performance.},
  language  = {en}
}
@article{KhodaverdiChaziioannouWeberetal.2004,
  author    = {Khodaverdi, M. and Chaziioannou, A. F. and Weber, S. and Ziemons, Karl and Halling, H. and Pietrzyk, U.},
  title     = {Investigation of different microCT scanner configurations by GEANT4 simulations},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  issn      = {1082-3654},
  pages     = {2989 -- 2993},
  year      = {2004},
  abstract  = {This study has been performed to design the combination of the new ClearPET TM (ClearPET is a trademark of the Crystal Clear Collaboration), a small animal Positron Emission Tomography (PET) system, with a microComputed Tomography (microCT) scanner. The properties of different microCT systems have been determined by simulations based on GEANT4. We demonstrate the influence of the detector material and the X-ray spectrum on the obtained contrast. Four different detector materials (selenium, cadmium zinc telluride, cesium iodide and gadolinium oxysulfide) and two X-ray spectra (a molybdenum and a tungsten source) have been considered. The spectra have also been modified by aluminum filters of varying thickness. The contrast between different tissue types (water, air, brain, bone and fat) has been simulated by using a suitable phantom. The results indicate the possibility to improve the image contrast in microCT by an optimized combination of the X-ray source and detector material.},
  language  = {en}
}
@article{ChristHollendungLarueetal.2004,
  author    = {Christ, D. and Hollendung, A. and Larue, H. and Parl, C. and Streun, M. and Weber, S. and Ziemons, Karl and Halling, H.},
  title     = {Homogenization of the MultiChannel PM gain by inserting light attenuating masks},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  issn      = {1082-3654},
  pages     = {2382 -- 2385},
  year      = {2004},
  abstract  = {MultiChannel Photomultipliers (PM), like the R7600-00-M64 or R5900-00-M64 from Hamamatsu, are often chosen as photodetectors in high-resolution positron emission tomography (PET). A major problem of this PM is the nonuniform channel gain. In order to solve this problem, light attenuating masks were created. The aim of the masks is a homogenization of the output of all 64 channels using different hole sizes at the channel positions. The hole area, which is individually defined for the different channels, is inversely proportional to the channel gain. The measurements by inserting light attenuating masks improved a homogenization to a ratio of 1:1.2.},
  language  = {en}
}
@inproceedings{TersteggeWeberHerzogetal.1997,
  author    = {Terstegge, Andreas and Weber, S. and Herzog, H. and M{\"u}ller-G{\"a}rtner, H. W. and Halling, H.},
  title     = {Design and implementation aspects of a 3D reconstruction algorithm for the J{\"u}lich TierPET system},
  series = {1997 International Meeting on Fully ThreeDimensional Image Reconstruction in Radiology and Nuclear Medicine : 3D97},
  booktitle = {1997 International Meeting on Fully ThreeDimensional Image Reconstruction in Radiology and Nuclear Medicine : 3D97},
  pages     = {170 -- 173},
  year      = {1997},
  language  = {en}
}
@inproceedings{WeberTersteggeEngelsetal.1996,
  author    = {Weber, S. and Terstegge, Andreas and Engels, R. and Herzog, H. and Reinartz, R. and Reinhart, P. and Rongen, F. and M{\"u}ller-G{\"a}rtner, H. W. and Halling, H.},
  title     = {The KFA TierPET: performance characteristics and measurements},
  series = {Conference record / 1996 IEEE Nuclear Science Symposium [and Medical Imaging], November 2 - 9, 1996, Anaheim, California ; vol. 2},
  booktitle = {Conference record / 1996 IEEE Nuclear Science Symposium [and Medical Imaging], November 2 - 9, 1996, Anaheim, California ; vol. 2},
  publisher = {IEEE},
  address   = {Piscataway, NJ},
  organization    = {Institute of Electrical and Electronics Engineers},
  isbn      = {0-7803-3534-1},
  issn      = {1082-3654},
  pages     = {1117 -- 1119},
  year      = {1996},
  language  = {en}
}
@inproceedings{WeberTersteggeHallingetal.1995,
  author    = {Weber, S. and Terstegge, Andreas and Halling, H. and Herzog, H. and Reinartz, R. and Reinhart, P. and Rongen, F. and M{\"u}ller-G{\"a}rtner, H.-W.},
  title     = {The design of an animal PET: flexible geometry for achieving optimal spatial resolution or high sensitivity},
  series = {Conference record / 1995 IEEE Nuclear Science Symposium and Medical Imaging, October 21 - 28, 1995, San Francisco ; vol. 2},
  booktitle = {Conference record / 1995 IEEE Nuclear Science Symposium and Medical Imaging, October 21 - 28, 1995, San Francisco ; vol. 2},
  publisher = {IEEE},
  address   = {Piscataway, NJ},
  organization    = {Institute of Electrical and Electronics Engineers},
  isbn      = {078033180X ; 0780331818 ; 0780331826},
  pages     = {1002 -- 1005},
  year      = {1995},
  language  = {en}
}