@article{Ziemons1987,
  author    = {Ziemons, Karl},
  title     = {Jet production and fragmentation properties in deep inelastic muon scattering},
  series = {Zeitschrift f{\"u}r Physik C : Particles and Fields},
  volume    = {36},
  journal   = {Zeitschrift f{\"u}r Physik C : Particles and Fields},
  number    = {4},
  isbn      = {0170-9739},
  pages     = {527 -- 543},
  year      = {1987},
  language  = {en}
}
@article{Ziemons1988,
  author    = {Ziemons, Karl},
  title     = {A measurement of the spin asymmetry of the structure function g1 in deep inelastic muon-proton scattering},
  series = {Physics Letters B},
  volume    = {206},
  journal   = {Physics Letters B},
  number    = {2},
  isbn      = {0370-2693},
  pages     = {364 -- 370},
  year      = {1988},
  abstract  = {The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured over a large x range (0.01<x<0.7). The spin-dependent structure function g1(x) for the proton has been determined and its integral over x found to be 0.114±0.012±0.026, in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Bjorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These values for the integrals of g1 lead to the conclusion that the total quark spin constitutes a rather small fraction of the spin of the nucleon.},
  language  = {en}
}
@article{ZiemonsBerghoffLanskeetal.1988,
  author    = {Ziemons, Karl and Berghoff, G. and Lanske, D. and Schultze, K.},
  title     = {Strangeness production in deep inelastic muon-nucleon scattering},
  series = {Verhandlungen der Deutschen Physikalischen Gesellschaft},
  volume    = {23},
  journal   = {Verhandlungen der Deutschen Physikalischen Gesellschaft},
  number    = {5},
  isbn      = {0420-0195},
  pages     = {T309 -- T309},
  year      = {1988},
  language  = {en}
}
@article{BerghoffLanskeSchultzeetal.1988,
  author    = {Berghoff, G. and Lanske, D. and Schultze, K. and Ziemons, Karl},
  title     = {Jets and QCD-effects in muon-nuclean scattering},
  series = {Verhandlungen der Deutschen Physikalischen Gesellschaft},
  volume    = {23},
  journal   = {Verhandlungen der Deutschen Physikalischen Gesellschaft},
  number    = {5},
  isbn      = {0420-0195},
  year      = {1988},
  language  = {en}
}
@article{Ziemons1989,
  author    = {Ziemons, Karl},
  title     = {An investigation of the spin structure of the proton in deep inelastic scattering of polarised muons and polarised protons},
  series = {Nuclear Physics B},
  volume    = {328},
  journal   = {Nuclear Physics B},
  number    = {1},
  isbn      = {0550-3213},
  pages     = {1 -- 35},
  year      = {1989},
  abstract  = {The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g1(x) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These integrals lead to the conclusion, in the na{\"i}ve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.},
  language  = {en}
}
@article{ZiemonsHerzogFeinendegen1990,
  author    = {Ziemons, Karl and Herzog, H. and Feinendegen, L. E.},
  title     = {Iterative image reconstruction with weighted pixel contribution to projection element},
  series = {European Journal of Nuclear Medicine},
  volume    = {16},
  journal   = {European Journal of Nuclear Medicine},
  number    = {7},
  isbn      = {1619-7089},
  pages     = {403 -- 403},
  year      = {1990},
  language  = {en}
}
@article{Ziemons1991,
  author    = {Ziemons, Karl},
  title     = {Comparison of forward hadrons produced in muon interactions on nuclear targets and deuterium},
  series = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  volume    = {52},
  journal   = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  number    = {1},
  isbn      = {1431-5858},
  pages     = {1 -- 11},
  year      = {1991},
  abstract  = {Differential multiplicities of forward produced hadrons in deep inelastic muon scattering on nuclear targets have been compared with those from deuterium. The ratios are observed to increase towards unity as the virtual photon energy increases with no significant dependence on the other muon kinematic variables. The hadron transverse momentum distribution is observed to be broadened in nuclear targets. The dependence on the remaining hadron variables is investigated and the results are discussed in the framework of intranuclear interaction models and in the context of the EMC effect.},
  language  = {en}
}
@article{Ziemons1992,
  author    = {Ziemons, Karl},
  title     = {Muoproduction of J/ψ and the gluon distribution of the nucleon},
  series = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  volume    = {56},
  journal   = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  number    = {1},
  isbn      = {1431-5858},
  pages     = {21 -- 28},
  year      = {1992},
  abstract  = {Measurements are presented of the inclusive distributions of the J/Ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04<x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use of J/Ψ productionby virtual photons to extract the gluon distribution at HERA.},
  language  = {en}
}
@article{ZiemonsHerzogBosettietal.1992,
  author    = {Ziemons, Karl and Herzog, H. and Bosetti, P. and Feinendegen, L. E.},
  title     = {Iterative image reconstruction with weighted pixel contribution to projection elements},
  series = {European Journal of Nuclear Medicine},
  volume    = {19},
  journal   = {European Journal of Nuclear Medicine},
  number    = {8},
  isbn      = {1619-7089},
  pages     = {588 -- 588},
  year      = {1992},
  language  = {en}
}
@article{Ziemons1993,
  author    = {Ziemons, Karl},
  title     = {A measurement of the ratio of the nucleon structure function in copper and deuterium},
  series = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  volume    = {57},
  journal   = {Zeitschrift f{\"u}r Physik C Particles and Fields},
  number    = {2},
  isbn      = {1431-5858},
  pages     = {211 -- 218},
  year      = {1993},
  abstract  = {Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function,F 2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.},
  language  = {en}
}
@article{BoeckerKuwertLangenetal.1994,
  author    = {Boecker, Henning and Kuwert, Torsten and Langen, Karl-J. and Lange, Herwig W. and Czech, Norbert and Ziemons, Karl and Herzog, Hans and Shikare, Shekar and Weindl, Anton and Feinendegen, Ludwig E.},
  title     = {SPECT with HMPAO compared to PET with FDG in Huntington disease},
  series = {Journal of Computer Assisted Tomography},
  volume    = {18},
  journal   = {Journal of Computer Assisted Tomography},
  number    = {4},
  isbn      = {1532-3145},
  pages     = {542 -- 548},
  year      = {1994},
  language  = {en}
}
@article{GriessmeierSonnenbergWeckesseretal.1996,
  author    = {Grießmeier, M. and Sonnenberg, F. and Weckesser, M. and Ziemons, Karl and Langen, K.-J. and M{\"u}ller-G{\"a}rtner, H. W.},
  title     = {Improvement of SPECT quantification in small brain structures by using experiment based recovery-coefficient corrections},
  series = {European Journal of Nuclear Medicine},
  volume    = {23},
  journal   = {European Journal of Nuclear Medicine},
  number    = {9},
  issn      = {1619-7089},
  pages     = {1238 -- 1238},
  year      = {1996},
  language  = {en}
}
@article{ZiemonsKleinesErkenetal.1997,
  author    = {Ziemons, Karl and Kleines, H. and Erken, I. and Knoben, J. and Zwoll, K.},
  title     = {IME-DV Projekt: M-FIRBe, Multi-Modality Functional Imaging for Brain Research},
  series = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  journal   = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  editor    = {Lehmann, Thomas},
  publisher = {Verl. der. Augustinus-Buchh.},
  address   = {Aachen},
  isbn      = {3-86073-519-5},
  pages     = {363 -- 366},
  year      = {1997},
  language  = {de}
}
@article{KleinesErkiZiemonsetal.1997,
  author    = {Kleines, H. and Erki, I. and Ziemons, Karl and Zwoll, K.},
  title     = {ATM- und Multimedia Pilotsystem im Rahmen des Projektes M-FIBRe Aufbau und Erfahrungen},
  series = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  journal   = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  editor    = {Lehmann, Thomas},
  publisher = {Verl. der. Augustinus-Buchh.},
  address   = {Aachen},
  isbn      = {3-86073-519-5},
  pages     = {241 -- 248},
  year      = {1997},
  language  = {de}
}
@article{ErkiKleinesZiemonsetal.1997,
  author    = {Erki, I. and Kleines, H. and Ziemons, Karl and Zwoll, K.},
  title     = {Interaktives System zur Darstellung funktionaler Bilddaten},
  series = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  journal   = {Bildverarbeitung f{\"u}r die Medizin : Algorithmen - Systeme - Anwendungen},
  editor    = {Lehmann, Thomas},
  publisher = {Verl. der. Augustinus-Buchh.},
  address   = {Aachen},
  isbn      = {3-86073-519-5},
  pages     = {249 -- 254},
  year      = {1997},
  language  = {de}
}
@article{LangenZiemonsKiwitetal.1997,
  author    = {Langen, Karl J. and Ziemons, Karl and Kiwit, J{\"u}rgen C. W. and Herzog, Hans and Kuwert, Torsten and Bock, Wolfgang and St{\"o}cklin, Gerhard and Feinendegen, Ludwig E. and M{\"u}ller-G{\"a}rtner, Hans-W.},
  title     = {3-[123I]iodo-α-methyltyrosine and [methyl-11C]-L-methionine uptake in cerebral gliomas: a compara-tive study using SPECT and PET},
  series = {Journal of Nuclear Medicine},
  volume    = {38},
  journal   = {Journal of Nuclear Medicine},
  number    = {4},
  isbn      = {0161-5505},
  pages     = {517 -- 522},
  year      = {1997},
  language  = {en}
}
@article{WeckesserHufnagelZiemonsetal.1997,
  author    = {Weckesser, Matthias and Hufnagel, Andreas and Ziemons, Karl and Grießmeier, Martin and Sonnenberg, Frank and Hackl{\"a}nder, Thomas and Langen, Karl-J. and Holschbach, Markus and Elger, Christian E. and M{\"u}ller-G{\"a}rtner, Hans-W.},
  title     = {Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy},
  series = {European Journal of Nuclear Medicine},
  volume    = {24},
  journal   = {European Journal of Nuclear Medicine},
  number    = {9},
  isbn      = {1619-7089},
  pages     = {1156 -- 1161},
  year      = {1997},
  abstract  = {Animal experiments and preliminary results in humans have indicated alterations of hippocampal muscarinic acetylcholine receptors (mAChR) in temporal lobe epilepsy. Patients with temporal lobe epilepsy often present with a reduction in hippocampal volume. The aim of this study was to investigate the influence of hippocampal atrophy on the quantification of mAChR with single photon emission tomography (SPET) in patients with temporal lobe epilepsy. Cerebral uptake of the muscarinic cholinergic antagonist [123I]4-iododexetimide (IDex) was investigated by SPET in patients suffering from temporal lobe epilepsy of unilateral (n=6) or predominantly unilateral (n=1) onset. Regions of interest were drawn on co-registered magnetic resonance images. Hippocampal volume was determined in these regions and was used to correct the SPET results for partial volume effects. A ratio of hippocampal IDex binding on the affected side to that on the unaffected side was used to detect changes in muscarinic cholinergic receptor density. Before partial volume correction a decrease in hippocampal IDex binding on the focus side was found in each patient. After partial volume no convincing differences remained. Our results indicate that the reduction in hippocampal IDex binding in patients with epilepsy is due to a decrease in hippocampal volume rather than to a decrease in receptor concentration.},
  language  = {en}
}
@article{SchmidtLangenHerzogetal.1997,
  author    = {Schmidt, Daniela and Langen, Karl-J. and Herzog, Hans and Wirths, Jochen and Holschbach, Markus and Kiwit, J{\"u}rgen C. W. and Ziemons, Karl and Coenen, Heinz-H. and M{\"u}ller-G{\"a}rtner, Hans-W.},
  title     = {Whole-body kinetics and dosimetry of L-3[123I]-iodo-α-methyltyrosine},
  series = {European Journal of Nuclear Medicine},
  volume    = {24},
  journal   = {European Journal of Nuclear Medicine},
  number    = {9},
  isbn      = {1619-7089},
  pages     = {1162 -- 1166},
  year      = {1997},
  language  = {en}
}
@article{WeckesserGriessmeierSchmidtetal.1998,
  author    = {Weckesser, Martin and Grießmeier, Martin and Schmidt, Daniela and Sonnenberg, Frank and Ziemons, Karl and Kemna, Lars and Holschbach, Marcus and Langen, Karl-J. and M{\"u}ller-G{\"a}rtner, Hans-W.},
  title     = {Iodine-123 α-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent},
  series = {European Journal of Nuclear Medicine},
  volume    = {25},
  journal   = {European Journal of Nuclear Medicine},
  number    = {2},
  isbn      = {1619-7089},
  pages     = {150 -- 156},
  year      = {1998},
  abstract  = {Single-photon emission tomography (SPET) with the amino acid analogue l-3-[123I]iodo-α-methyl tyrosine (IMT) is helpful in the diagnosis and monitoring of cerebral gliomas. Radiolabelled amino acids seem to reflect tumour infiltration more specifically than conventional methods like magnetic resonance imaging and computed tomography. Automatic tumour delineation based on maximal tumour uptake may cause an overestimation of mean tumour uptake and an underestimation of tumour extension in tumours with circumscribed peaks. The aim of this study was to develop a program for tumour delineation and calculation of mean tumour uptake which takes into account the mean background activity and is thus optimised to the problem of tumour definition in IMT SPET. Using the frequency distribution of pixel intensities of the tomograms a program was developed which automatically detects a reference brain region and draws an isocontour region around the tumour taking into account mean brain radioactivity. Tumour area and tumour/brain ratios were calculated. A three-compartment phantom was simulated to test the program. The program was applied to IMT SPET studies of 20 patients with cerebral gliomas and was compared to the results of manual analysis by three different investigators. Activity ratios and chamber extension of the phantom were correctly calculated by the automatic analysis. A method based on image maxima alone failed to determine chamber extension correctly. Manual region of interest analysis in patient studies resulted in a mean inter-observer standard deviation of 8.7\%±6.1\% (range 2.7\%-25.0\%). The mean value of the results of the manual analysis showed a significant correlation to the results of the automatic analysis (r = 0.91, P<0.0001 for the uptake ratio; r = 0.87, P<0.0001 for the tumour area). We conclude that the algorithm proposed simplifies the calculation of uptake ratios and may be used for observer-independent evaluation of IMT SPET studies. Three-dimensional tumour recognition and transfer to co-registered morphological images based on this program may be useful for the planning of surgical and radiation treatment.},
  language  = {en}
}
@article{TaylorSchmitzZiemonsetal.2000,
  author    = {Taylor, J. G. and Schmitz, N. and Ziemons, Karl and Grosse-Ruyken, M.-L. and Gruber, O. and M{\"u}ller-G{\"a}rtner, H.-W. and Shah, N. J.},
  title     = {The network of brain areas involved in the motion aftereffect},
  series = {Neuroimage},
  volume    = {11},
  journal   = {Neuroimage},
  number    = {4},
  isbn      = {1053-8119},
  pages     = {257 -- 270},
  year      = {2000},
  abstract  = {A network of brain areas is expected to be involved in supporting the motion aftereffect. The most active components of this network were determined by means of an fMRI study of nine subjects exposed to a visual stimulus of moving bars producing the effect. Across the subjects, common areas were identified during various stages of the effect, as well as networks of areas specific to a single stage. In addition to the well-known motion-sensitive area MT the prefrontal brain areas BA44 and 47 and the cingulate gyrus, as well as posterior sites such as BA37 and BA40, were important components during the period of the motion aftereffect experience. They appear to be involved in control circuitry for selecting which of a number of processing styles is appropriate. The experimental fMRI results of the activation levels and their time courses for the various areas are explored. Correlation analysis shows that there are effectively two separate and weakly coupled networks involved in the total process. Implications of the results for awareness of the effect itself are briefly considered in the final discussion.},
  language  = {en}
}
@article{FinkMarshallShahetal.2000,
  author    = {Fink, G. R. and Marshall, J. C. and Shah, N. J. and Weiss, P.H. and Halligan, P. W. and Grosse-Ruyken, M. and Ziemons, Karl and Zilles, K. and Freund, H. J.},
  title     = {Line bisection judgments implicate right parietal cortex and cerebellum as assessed by fMRI},
  series = {Neurology},
  volume    = {54},
  journal   = {Neurology},
  number    = {6},
  isbn      = {1526-632X},
  pages     = {1324 -- 1331},
  year      = {2000},
  language  = {en}
}
@article{BussmannEngelsFussetal.2000,
  author    = {Bussmann, N. and Engels, R. and Fuss, L. and Kemmerling, G. and Reinartz, R. and Langen, K.-J. and Schelten, J. and Ziemons, Karl},
  title     = {Performance measurement of a new high resolution detector system for I-131 thyroid studies},
  series = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {22/35 -- 22/37},
  year      = {2000},
  abstract  = {A 2-dimensional detector system for high resolution thyroid I-131 scintigraphy was developed. It has a sensitive area of 4 cm×4 cm and consists of a lead-collimator and an array of 10×10 EGO crystals combined with a position sensitive photomultiplier. The spatial resolution and the sensitivity of the detector has been measured and compared to two commercially available gamma-cameras. Furthermore first patient measurements have been carried out},
  language  = {de}
}
@article{StreunBrandenburgLarueetal.2000,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse recording by free-running sampling},
  series = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  journal   = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  issn      = {1082-3654},
  pages     = {9/179 -- 9/181},
  year      = {2000},
  abstract  = {Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free running ADCs at a sampling rate of 40 MHz. A four-channel acquisition-board has been developed which is equipped with four 12 bit-ADCs connected to one FPGA (field programmable gate array). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware-trigger can be omitted. The method of free running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. These informations are crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows coping with very high count rates. Since this method is going to be employed in positron emission tomography (PET), the position of an event is another important information. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO-scintillators coupled to the PS-PMT are presented},
  language  = {en}
}
@inproceedings{PetersZiemonsDammersetal.2001,
  author    = {Peters, H. and Ziemons, Karl and Dammers, J. and M{\"u}ller-Veggian, Mattea},
  title     = {Continuous head motion detection during MEG measurement using head location coils},
  series = {Proceedings of the 12th International Conference on Biomagnetism : August 13 - 17, 2000, Helsinki University of Technology, Espoo, Finland},
  booktitle = {Proceedings of the 12th International Conference on Biomagnetism : August 13 - 17, 2000, Helsinki University of Technology, Espoo, Finland},
  editor    = {Nenonen, Jukka},
  publisher = {Helsinki Univ. of Technology, Laboratory of Biomedical Engineering},
  address   = {Espoo},
  isbn      = {951-22-5401-8},
  pages     = {XX, 1060 S. : Ill., graph. Darst.},
  year      = {2001},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2001,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse recording by free-running sampling},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {48},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {3},
  isbn      = {0018-9499},
  pages     = {524 -- 526},
  year      = {2001},
  abstract  = {Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free-running ADCs at a sampling rate of 40 MHz. A four-channel acquisition board has been developed which is equipped with four 12-bit ADCs connected to one field programmable gate array (FPGA). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware trigger can be omitted. The method of free-running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. This information is crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows very high count rates to be dealt with. Since this method is to be employed in positron emission tomography (PET), the position of an event is also important. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO scintillators coupled to the PS-PMT are presented here},
  language  = {en}
}
@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{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {A PET system with free running ADCs},
  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     = {18 -- 21},
  year      = {2002},
  abstract  = {A small PET system has been built up with two multichannel photomultipliers, which are attached to a matrix of 64 single LSO crystals each. The signal from each multiplier is being sampled continuously by a 12 bit ADC at a sampling frequency of 40 MHz. In case of a scintillation pulse a subsequent FPGA sends the corresponding set of samples together with the channel information and a time mark to the host computer. The data transfer is performed with a rate of 20 MB/s. On the host all necessary information is extracted from the data. The pulse energy is determined, coincident events are detected and multiple hits within one matrix can be identified. In order to achieve a narrow time window the pulse starting time is refined further than the resolution of the time mark (=25 ns) would allow. This is possible by interpolating between the pulse samples. First data obtained from this system will be presented. The system is part of developments for a much larger system and has been created to study the feasibility and performance of the technique and the hardware architecture.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Coincidence detection by digital processing of free-running sampled pulses},
  series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {487},
  journal   = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {3},
  isbn      = {0168-9002},
  pages     = {530 -- 534},
  year      = {2002},
  abstract  = {Coincident events in two scintillator crystals coupled to photomultipliers (PMT) are detected by processing just the digital data of the recorded pulses. For this purpose the signals from both PMTs are continuously sampled by free-running ADCs at a sampling rate of 40 MHz. For each sampled pulse the starting time is determined by processing the pulse data. Even a fairly simple interpolating algorithm results in a FWHM of about 2 ns.},
  language  = {en}
}
@article{KhodaverdiPaulySchroderetal.2002,
  author    = {Khodaverdi, M. and Pauly, F. and Schroder, G. and Ziemons, Karl and Sievering, R. and Halling, H.},
  title     = {Preliminary studies of a micro-CT for a combined small animal PET/CT scanner},
  series = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {1605 -- 1606},
  year      = {2002},
  abstract  = {We are developing an X-ray computed tomography (CT) system which will be combined with a high resolution animal PET system. This permits acquisition of both molecular and anatomical images in a single machine. In particular the CT will also be utilized for the quantification of the animal PET data by providing accurate data for attenuation correction. A first prototype has been built using a commercially available plane silicon diode detector. A cone-beam reconstruction provides the images using the Feldkamp algorithm. First measurements with this system have been performed on a mouse. It could be shown that the CT setup fulfils all demands for a high quality image of the skeleton of the mouse. It is also suited for soft tissue measurements. To improve contrast and resolution and to acquire the X-ray energy further development of the system, especially the use of semiconductor detectors and iterative reconstruction algorithms are planned.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {A PET system based on data processing of free-running sampled pulses},
  series = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  journal   = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  issn      = {1082-3654},
  pages     = {693 -- 694},
  year      = {2002},
  abstract  = {Within the developments for the Crystal Clear small animal PET project (CLEARPET) a dual head PET system has been established. The basic principle is the early digitization of the detector pulses by free running ADCs. The determination of the γ-energy and also the coincidence detection is performed by data processing of the sampled pulses on the host computer. Therefore a time mark is attached to each pulse identifying the current cycle of the 40 MHz sampling clock. In order to refine the time resolution the pulse starting time is interpolated from the samples of the pulse rise. The detector heads consist of multichannel PMTs with a single LSO scintillator crystal coupled to each channel. For each PMT only one ADC is required. The position of an event is obtained separately from trigger signals generated for each single channel. An FPGA is utilized for pulse buffering, generation of the time mark and for the data transfer to the host via a fast I/O-interface.},
  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{StreunBrandenburgLarueetal.2003,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Saleh, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET},
  series = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {1636 -- 1639},
  year      = {2003},
  abstract  = {A feasible way to gain the depth of interaction information in a PET scanner is the use of phoswich detectors. In general the layer of interaction is identified front the pulse shape of the corresponding scintillator material. In this work pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could he kept simple due to an additional slow component in the light decay of the LuYAP pulse. At the same time the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2003,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Saleh, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {50},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {3},
  isbn      = {0018-9499},
  pages     = {344 -- 347},
  year      = {2003},
  abstract  = {A feasible way to gain the depth of interaction information in a positron emission tomography scanner is the use of phoswich detectors. In general, the layer of interaction is identified from the pulse shape of the corresponding scintillator material. In this work, pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could be kept simple because of an additional slow component in the light decay of the LuYAP pulse. At the same time, the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.},
  language  = {en}
}
@article{ZiemonsAchtenAuffrayetal.2004,
  author    = {Ziemons, Karl and Achten, R. and Auffray, E. and M{\"u}ller-Veggian, Mattea},
  title     = {The ClearPET™ neuro scanner: a dedicated LSO/LuYAP phoswich small animal PET scanner},
  series = {2004 IEEE Nuclear Science Symposium conference record : Nuclear Science Symposium, Medical Imaging Conference ; 16 - 22 October 2004, Rome, Italy ; [including the Symposium on Nuclear Power System (SNPS), 14th Room Temperature Semiconductor X- and Gamma-Ray Detectors Workshop and special focus workshops] / NPSS, Nuclear \& Plasma Sciences Society. Guest ed.: J. Anthony Seibert},
  journal   = {2004 IEEE Nuclear Science Symposium conference record : Nuclear Science Symposium, Medical Imaging Conference ; 16 - 22 October 2004, Rome, Italy ; [including the Symposium on Nuclear Power System (SNPS), 14th Room Temperature Semiconductor X- and Gamma-Ray Detectors Workshop and special focus workshops] / NPSS, Nuclear \& Plasma Sciences Society. Guest ed.: J. Anthony Seibert},
  publisher = {IEEE Operations Center},
  address   = {Piscataway, NJ},
  issn      = {1082-3654},
  pages     = {2430 -- 2433},
  year      = {2004},
  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{ZiemonsAuffrayBarbieretal.2004,
  author    = {Ziemons, Karl and Auffray, E. and Barbier, R. and Brandenburg, G.},
  title     = {The ClearPET TM LSO/LuYAP phoswich scanner: a high performance small animal PET system},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {1728 -- 1732},
  year      = {2004},
  abstract  = {A 2nd generation high performance small animal PET scanner, called ClearPET™, has been designed and a first prototype is built by working groups of the Crystal Clear Collaboration (CCC). In order to achieve high sensitivity and maintain good uniform spatial resolution over the field of view in high resolution PET systems, it is necessary to extract the depth of interaction (DOI) information and correct for spatial degradation. The design of the first ClearPET™ Demonstrator based on the use of the multi-anode photomultiplier tube (Hamamatsu R7600-M64) and a LSO/LuYAP phoswich matrix. The two crystal layers of 8*8 crystals (2*2*10 mm3) are stacked on each other and mounted without light guide as one to one on the PMT. A unit of four PMTs arranged in-line represents one of 20 sectors of the ring design. The opening diameter of the crystal ring is 137 mm, the axial detector length is 110 mm. The PMT pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the pulse arrival time. Single gamma interactions are recorded and coincidences are found by software. The gantry allows rotation of the detector modules around the field of view. The measurements have been done using the first LSO/LuYAP detector cassettes.},
  language  = {en}
}
@article{StreunBrandenburgBroekeletal.2004,
  author    = {Streun, M. and Brandenburg, G. and Br{\"o}kel, M. and Fuss, L. and Larue, H. and Parl, C. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {The ClearPET data acquisition},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  issn      = {1082-3654},
  pages     = {3097 -- 3100},
  year      = {2004},
  abstract  = {Within the Crystal Clear Collaboration a modular system for a small animal PET scanner (ClearPET™) has been developed. The modularity allows the assembly of scanners of different sizes and characteristics in order to fit the specific needs of the individual member institutions. Now a first demonstrator is being completed in Julich. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to multi-channel photomultipliers (PMTs). A free-running ADC digitizes the signal from the PMT and the complete scintillation pulses are sampled by an FPGA and sent with 20 MB/S to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. An advantage of that is that the coincidence window and the dimensions of the field of view can be adjusted easily. The ClearPET™ demonstrator is equipped with 10240 crystals on 80 PMTs. This paper presents an overview of the data acquisition system.},
  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}
}
@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{AuffrayBruyndonckxDevroedeetal.2004,
  author    = {Auffray, E. and Bruyndonckx, P. and Devroede, O. and Fedorov, A. and Ziemons, Karl},
  title     = {The ClearPET project},
  series = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {527},
  journal   = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {1-2},
  isbn      = {0168-9002},
  pages     = {171 -- 174},
  year      = {2004},
  abstract  = {The Crystal Clear Collaboration has designed and is building a high-resolution small animal PET scanner. The design is based on the use of the Hamamatsu R7600-M64 multi-anode photomultiplier tube and a LSO/LuYAP phoswich matrix with one to one coupling between the crystals and the photo-detector. The complete system will have 80 PM tubes in four rings with an inner diameter of 137 mm and an axial field of view of 110 mm. The PM pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the pulse arrival time. Single gamma interactions are recorded and coincidences are found by software. The gantry allows rotation of the detector modules around the field of view. Simulations, and measurements a 2×4 module test set-up predict a spatial resolution of 1.5 mm in the centre of the field of view and a sensitivity of 5.9\% for a point source in the centre of the field of view.},
  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}
}
@misc{AchtenBauerBertrametal.2005,
  author    = {Achten, Richard and Bauer, Andreas and Bertram, Walter and Cremer, Markus and Daemen, Jos and Dehnhardt, Markus and Fleischer, Manfred and Kirchner, Peter and Leyendecker, Marco and Pietrzyk, Uwe and Schmitz, Jakob and Ziemons, Karl and Zilles, Karl},
  title     = {Vorrichtung zum Halten eines lebenden Objektes bei physiologischen Messungen},
  pages     = {1 -- 17},
  year      = {2005},
  abstract  = {Die vorliegende Erfindung betrifft eine Vorrichtung zum Halten eines lebenden Objektes bei physiologischen Messungen mit einem Basiselement und Mitteln zum Arretieren des lebenden Objektes, die atraumatische Ohrenhalter sowie ein Mundst{\"u}ck aufweisen, das mit einer Aussparung f{\"u}r die Z{\"a}hne des Lebewesens versehen ist, mit einem Masseanteil von wenigstens 95\% an glasfaserverst{\"a}rktem Kunststoff.},
  language  = {de}
}
@article{StreunChristHellendungetal.2005,
  author    = {Streun, M. and Christ, D. and Hellendung, A. and Larue, H. and Ziemons, Karl and Halling, H.},
  title     = {Effects of crosstalk and gain nonuniformity using multichannel PMTs in the Clearpet® scanner},
  series = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {537},
  journal   = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {1-2},
  isbn      = {0168-9002},
  pages     = {402 -- 405},
  year      = {2005},
  abstract  = {The ClearPET® scanners developed by the Crystal Clear Collaboration use multichannel PMTs as photodetectors with scintillator pixels coupled individually to each channel. In order to localize an event each channel anode is connected to a comparator that triggers when the anode signal exceeds a common predefined threshold. Two major difficulties here are crosstalk of light and the gain nonuniformity of the PMT channels. Crosstalk can generate false triggering in channels adjacent to the actual event. On the one hand this can be suppressed by sufficiently increasing the threshold, but on the other hand a threshold too high can already prevent valid events on the lower gain channels from being detected. Finally, both effects restrict the dynamic range of pulse heights that can be processed. The requirements to the dynamic range are not low as the ClearPET® scanners detect the depth of interaction by phoswich pixels consisting of LSO and Lu0.7Y0.3AP, two scintillators with different light yields. We will present a model to estimate the achievable dynamic range and show solutions to increase it.},
  language  = {en}
}
@article{ZiemonsAuffrayBarbieretal.2005,
  author    = {Ziemons, Karl and Auffray, E. and Barbier, R. and Brandenburg, G. and Bruyndonckx, P.},
  title     = {The ClearPET™ project: Development of a 2nd generation high-performance small animal PET scanner},
  series = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {537},
  journal   = {Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {1-2},
  issn      = {0168-9002},
  pages     = {307 -- 311},
  year      = {2005},
  abstract  = {Second generation high-performance PET scanners, called ClearPET™1, have been developed by working groups of the Crystal Clear Collaboration (CCC). High sensitivity and high spatial resolution for the ClearPET camera is achieved by using a phoswich arrangement combining two different types of lutetium-based scintillator materials: LSO from CTI and LuYAP:Ce from the CCC (ISTC project). In a first ClearPET prototype, phoswich arrangements of 8×8 crystals of 2×2×10 mm3 are coupled to multi-channel photomultiplier tubes (Hamamatsu R7600). A unit of four PMTs arranged in-line represents one of 20 sectors of the ring design. The opening diameter of the ring is 120 mm, the axial detector length is 110 mm.The PMT pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the exact pulse starting time, which is subsequently used for coincidence detection. The gantry allows rotation of the detector modules around the field of view. Preliminary data shows a correct identification of the crystal layer about (98±1)\%. Typically the energy resolution is (23.3±0.5)\% for the luyap layer and (15.4±0.4)\% for the lso layer. early studies showed the timing resolution of 2 ns FWHM and 4.8 ns FWTM. the intrinsic spatial resolution ranges from 1.37 mm to 1.61 mm full-width of half-maximum (FWHM) with a mean of 1.48 mm FWHM. further improvements in image and energy resolution are expected when the system geometry is fully modeled.},
  language  = {en}
}
@article{StreunChavanLameetal.2006,
  author    = {Streun, M. and Chavan, U. and Lame, H. and Parl, C. and M{\"u}ller-Veggian, Mattea and Ziemons, Karl},
  title     = {Treating the Gain Non-Uniformity of Multi Channel PMTs by Channel-Specific Trigger Levels},
  series = {2006 IEEE Nuclear Science Symposium Conference Record, Vol. 2.},
  journal   = {2006 IEEE Nuclear Science Symposium Conference Record, Vol. 2.},
  address   = {San Diego, CA},
  issn      = {1082-3654},
  pages     = {1301 -- 1304},
  year      = {2006},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2006,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Parl, C. and Ziemons, Karl},
  title     = {The data acquisition system of ClearPET neuro - a small animal PET scanner},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {53},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {3},
  isbn      = {0018-9499},
  pages     = {700 -- 703},
  year      = {2006},
  abstract  = {The Crystal Clear Collaboration has developed a modular system for a small animal PET scanner (ClearPET). The modularity allows the assembly of scanners of different sizes and characteristics in order to satisfy the specific needs of the individual member institutions. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to Multichannel Photomultipliers (PMTs). For each PMT a free running 40 MHz ADC digitizes the signal and the complete scintillation pulse is sampled by an FPGA and sent with 20 MB/s to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. The system in J{\"u}lich (ClearPET Neuro) is equipped with 10240 crystals on 80 PMTs. The paper will present an overview of the data acquisition system.},
  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{StreunBrandenburgKhodaverdietal.2006,
  author    = {Streun, M. and Brandenburg, G. and Khodaverdi, M. and Larue, H. and Parl, C. and Ziemons, Karl},
  title     = {Timemark correction for the ClearPET™ scanners},
  series = {2005 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  journal   = {2005 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  isbn      = {1082-3654},
  pages     = {2057 -- 2060},
  year      = {2006},
  abstract  = {The small animal PET scanners developed by the Crystal Clear Collaboration (ClearPETtrade) detect coincidences by analyzing timemarks which are attached to each event. The scanners are able to save complete single list mode data which allows analysis and modification of the timemarks after data acquisition. The timemarks are obtained from the digitally sampled detector pulses by calculating the baseline crossing of the rising edge of the pulse which is approximated as a straight line. But the limited sampling frequency causes a systematic error in the determination of the timemark. This error depends on the phase of the sampling clock at the time of the event. A statistical method that corrects these errors will be presented},
  language  = {en}
}
@article{MossetDevroedeKriegueretal.2006,
  author    = {Mosset, J.-B. and Devroede, O. and Krieguer, M. and Rey, M. and Vieira, J.-M. and Jung, J. H. and Kuntner, C. and Streun, M. and Ziemons, Karl and Auffray, E. and Sempere-Roldan, P. and Lecoq, P. and Bruyndonckx, P. and Loude, J.-F. and Tavernier, S. and Morcel, C.},
  title     = {Development of an optimized LSO/LuYAP phoswich detector head for the Lausanne ClearPET demonstrator},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {53},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {1},
  isbn      = {0018-9499},
  pages     = {25 -- 29},
  year      = {2006},
  abstract  = {This paper describes the LSO/LuYAP phoswich detector head developed for the ClearPET small animal PET scanner demonstrator that is under construction in Lausanne within the Crystal Clear Collaboration. The detector head consists of a dual layer of 8×8 LSO and LuYAP crystal arrays coupled to a multi-anode photomultiplier tube (Hamamatsu R7600-M64). Equalistion of the LSO/LuYAP light collection is obtained through partial attenuation of the LSO scintillation light using a thin aluminum deposit of 20-35 nm on LSO and appropriate temperature regulation of the phoswich head between 30°C to 60°C. At 511keV, typical FWHM energy resolutions of the pixels of a phoswich head amounts to (28±2)\% for LSO and (25±2)\% for LuYAP. The LSO versus LuYAP crystal identification efficiency is better than 98\%. Six detector modules have been mounted on a rotating gantry. Axial and tangential spatial resolutions were measured up to 4 cm from the scanner axis and compared to Monte Carlo simulations using GATE. FWHM spatial resolution ranges from 1.3 mm on axis to 2.6 mm at 4 cm from the axis.},
  language  = {en}
}
@misc{RongenZiemonsSchieketal.2006,
  author    = {Rongen, Heinz and Ziemons, Karl and Schiek, Michael and Tass, Alexander},
  title     = {Vorrichtung zur Messung biomedizinischer Daten eines Probanden und Verfahren zur Simulation des Probanden mit in Echtzeit verarbeiteten Daten},
  pages     = {1 -- 12},
  year      = {2006},
  abstract  = {Die Erfindung betrifft eine Vorrichtung zur Messung biomedizinischer Daten eines Probanden, mit einem Messsystem zur Erhebung der Daten sowie einer ersten Hardware-Komponente zur Aufzeichnung der Daten. In einer Verbindungsleitung zur {\"U}bertragung der Daten vom Messsystem zur ersten Hardware-Komponente zur Aufzeichnung der Daten ist erfindungsgem{\"a}ss ein Mittel zur galvanischen Auftrennung der Daten angeordnet. Auf diese Weise ist wenigstens die Duplizierung der Daten f{\"u}r Datenverarbeitungszwecke gew{\"a}hrleistet. Die auf diese Weise verarbeiteten Daten werden f{\"u}r ein Verfahren zur Echtzeit-Stimulation eines Probanden genutzt.},
  language  = {de}
}
@article{StreunBeerHombachetal.2008,
  author    = {Streun, M. and Beer, S. and Hombach, T. and Jahnke, S. and Khodaverdi, M. and Larue, H. and Minwuyelet, S. and Parl, C. and Roeb, G. and Schurr, U. and Ziemons, Karl},
  title     = {PlanTIS: A positron emission tomograph for imaging 11C transport in plants},
  series = {2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6},
  journal   = {2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6},
  isbn      = {1082-3654},
  pages     = {4110 -- 4112},
  year      = {2008},
  abstract  = {Plant growth and transport processes are highly dynamic. They are characterized by plant-internal control processes and by strong interactions with the spatially and temporally varying environment. Analysis of structure- function relations of growth and transport in plants will strongly benefit from the development of non-invasive techniques. PlanTIS (Plant Tomographic Imaging System) is designed for non-destructive 3D-imaging of positron emitting radiotracers. It will permit functional analysis of the dynamics of carbon distribution in plants including bulky organs. It will be applicable for screening transport properties of plants to evaluate e.g. temperature adaptation of genetically modified plants. PlanTIS is a PET scanner dedicated to monitor the dynamics of the 11C distribution within a plant while or after assimilation of 11CO2. Front end electronics and data acquisition architecture of the scanner are based on the ClearPETTM system [1]. Four detector modules form one of two opposing detector blocks. Optionally, a hardware coincidence detection between the blocks can be applied. In general the scan duration is rather long (~ 1 hour) compared to the decay time of 11C (20 min). As a result the count rates can vary over a wide range and accurate dead time correction is necessary.},
  language  = {en}
}
@article{ZiemonsBruyndonckxPerezetal.2008,
  author    = {Ziemons, Karl and Bruyndonckx, P. and Perez, J. M. and Pietrzyk, U. and Rato, P. and Tavernier, S.},
  title     = {Beyond ClearPET: Next Aims},
  series = {5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008},
  journal   = {5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008},
  isbn      = {978-1-4244-2003-2},
  pages     = {1421 -- 1424},
  year      = {2008},
  abstract  = {The CRYSTAL CLEAR collaboration, in short CCC, is a consortium of 12 academic institutions, mainly from Europe, joining efforts in the area of developing instrumentation for nuclear medicine and medical imaging. In the framework of the CCC a high performance small animal PET system, called ClearPET, was developed by using new technologies in electronics and crystals in a phoswich arrangement combining two types of lutetium- based scintillator materials: LSO:Ce and LuYAP:Ce. Our next aim will be the development of hybrid image systems. Hybrid MR-PET imaging has many unique advantages for brain research. This has sparked a new research line within CCC for the development of novel MR-PET compatible technologies. MRI is not as sensitive as PET but PET has poorer spatial resolution than MRI. Two major advantages of PET are sensitivity and its ability to acquire metabolic information. To assess these innovations, the development of a 9.4T hybrid animal MR-PET scanner is proposed based on an existing 9.4T MR scanner that will be adapted to enable simultaneous acquisition of MR and PET data using cutting- edge technology for both MR and PET.},
  language  = {en}
}
@article{JahnkeMenzelDusschotenetal.2009,
  author    = {Jahnke, Siegfried and Menzel, Marion I. and Dusschoten, Dagmar van and Roeb, Gerhard W. and B{\"u}hler, Jonas and Minwuyelet, Senay and Bl{\"u}mler, Peter and Temperton, Vicky M. and Hombach, Thomas and Streun, Matthias and Beer, Simone and Khodaverdi, Maryam and Ziemons, Karl and Coenen, Heinz H. and Schurr, Ulrich},
  title     = {Combined MRI-PET dissects dynamic changes in plant structures and functions},
  series = {The Plant Journal},
  volume    = {59},
  journal   = {The Plant Journal},
  number    = {4},
  publisher = {Wiley},
  address   = {Weinheim},
  isbn      = {1365-313X},
  pages     = {634 -- 644},
  year      = {2009},
  abstract  = {Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope 11C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI-PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.},
  language  = {en}
}
@article{WedrowskiBruyndonckxTavernieretal.2009,
  author    = {Wedrowski, M. and Bruyndonckx, P. and Tavernier, S. and Zhi, L. and Dang, J. and Mendes, P. R. and Perez, J. M. and Ziemons, Karl},
  title     = {Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography},
  series = {2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  journal   = {2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  isbn      = {1082-3654},
  pages     = {2625 -- 2628},
  year      = {2009},
  abstract  = {The monolithic scintillator block approach for gamma detection in the Positron Emission Tomography (PET) avoids estimating Depth of Interaction (DOI), reduces dead zones in detector and diminishes costs of detector production. Neural Networks (NN) are very efficient to determine the entrance point of a gamma incident on a scintillator block. This paper presents results on the robustness of the spatial resolution as a function of the random fraction in the data, temperature and HV fluctuations. This is important when implementing the method in a real scanner. Measurements were done with two Hamamatsu S8550 APD arrays, glued on a 20 {\~A}— 20 {\~A}— 10 mm3 monolithic LSO crystal block.},
  language  = {en}
}
@article{StreunLarueParletal.2009,
  author    = {Streun, M. and Larue, H. and Parl, C. and Ziemons, Karl},
  title     = {A compact PET detector readout using charge-to-time conversion},
  series = {2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  journal   = {2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  publisher = {IEEE},
  address   = {New York},
  isbn      = {1082-3654},
  pages     = {1868 -- 1870},
  year      = {2009},
  abstract  = {The readout of gamma detectors is considerably simplified when the event intensity is encoded as a pulse width (Pulse Width Modulation, PWM). Time-to-Digital-Converters (TDC) replace the conventional ADCs and multiple TDCs can be realized easily in one PLD chip (Programmable Logic Device). The output of a PWM stage is only one digital signal per channel which is well suited for transport so that further processing can be performed apart from the detector. This is particularly interesting for large systems with high channel density (e.g. high resolution scanners). In this work we present a circuit with a linear transfer function that requires a minimum of components by performing the PWM already in the preamp stage. This allows a very compact and also cost-efficient implementation of the front-end electronics.},
  language  = {en}
}
@article{HerzogPietrzykShahetal.2010,
  author    = {Herzog, Hans and Pietrzyk, Uwe and Shah, N. Jon and Ziemons, Karl},
  title     = {The current state, challenges and perspectives of MR-PET},
  series = {Neuroimage},
  volume    = {49},
  journal   = {Neuroimage},
  number    = {3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1053-8119},
  doi       = {10.1016/j.neuroimage.2009.10.036},
  pages     = {2072 -- 2082},
  year      = {2010},
  abstract  = {Following the success of PET/CT during the last decade and the recent increasing proliferation of SPECT/CT, another hybrid imaging instrument has been gaining more and more interest: MR-PET. First combined, simultaneous PET and MR studies carried out in small animals demonstrated the feasibility of the new approach. Concurrently, some prototypes of an MR-PET scanner for simultaneous human brain studies have been built, their performance is being tested and preliminary applications have already been shown. Through this pioneering work, it has become clear that advances in the detector design are necessary for further optimization. Recently, the different issues related to the present state and future prospects of MR-PET were presented and discussed during an international 2-day workshop at the Forschungszentrum J{\"u}lich, Germany, held after, and in conjunction with, the 2008 IEEE Nuclear Science Symposium and Medical Imaging Conference in Dresden, Germany on October 27-28, 2008. The topics ranged from small animal MR-PET imaging to human MR-BrainPET imaging, new detector developments, challenges/opportunities for ultra-high field MR-PET imaging and considerations of possible future research and clinical applications. This report presents a critical summary of the contributions made to the workshop.},
  language  = {en}
}
@article{BeerStreunHombachetal.2010,
  author    = {Beer, S. and Streun, M. and Hombach, T. and Buehler, J. and Jahnke, S. and Khodaverdi, M. and Larue, H. and Minwuyelet, S. and Parl, C. and Roeb, G. and Schurr, U. and Ziemons, Karl},
  title     = {Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants},
  series = {Physics in Medicine and Biology},
  volume    = {55},
  journal   = {Physics in Medicine and Biology},
  number    = {3},
  publisher = {IOP},
  address   = {Bristol},
  issn      = {1361-6560},
  doi       = {10.1088/0031-9155/55/3/006},
  pages     = {635 -- 646},
  year      = {2010},
  abstract  = {Positron emitters such as 11C, 13N and 18F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is 11CO2 since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET™ system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.},
  language  = {en}
}
@article{ParlLarueStreunetal.2011,
  author    = {Parl, C. and Larue, H. and Streun, M. and Ziemons, Karl},
  title     = {Double-side-readout technique for SiPM-matrices},
  series = {2010 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  journal   = {2010 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  publisher = {IEEE},
  address   = {New York},
  issn      = {1095-7863},
  pages     = {1486 -- 1487},
  year      = {2011},
  abstract  = {In our case the double-side-method is used to minimize the complexity of a matrix-readout. Here the number of channels is reduced to 2√N̅. It is also possible to benefit from the method in a single pixel readout system. One signal can be used to measure position and energy of the event, the other one can be applied to a fast trigger-circuit at the same time. In a next step we will investigate timing behavior and electrical crosstalk of the circuit.},
  language  = {en}
}
@inproceedings{StreunAlKaddoumParletal.2012,
  author    = {Streun, M. and Al-Kaddoum, R. and Parl, C. and Pietrzyk, U. and Ziemons, Karl and Waasen, S. van},
  title     = {Simulation studies of optical photons in monolithic block scintillators},
  series = {2011 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  booktitle = {2011 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)},
  publisher = {IEEE},
  address   = {New York},
  isbn      = {978-1-4673-0120-6 (electronic ISBN)},
  doi       = {10.1109/NSSMIC.2011.6154621},
  pages     = {1380 -- 1382},
  year      = {2012},
  abstract  = {The interest in PET detectors with monolithic block scintillators is growing. In order to obtain high spatial resolutions dedicated positioning algorithms are required. But even an ideal algorithm can only deliver information which is provided by the detector. In this simulation study we investigated the light distribution on one surface of cuboid LSO scintillators of different size. Scintillators with a large aspect ratio (small footprint and large height) showed significant position information only for a minimum interaction depth of the gamma particle. The results allow a quantitative estimate for a useful aspect ratio.},
  language  = {en}
}
@article{GaribaldiBegingCaneseetal.2017,
  author    = {Garibaldi, F. and Beging, Stefan and Canese, R. and Carpinelli, G. and Clinthorne, N. and Colilli, S. and Cosentino, L. and Finocchiaro, P. and Giuliani, F. and Gricia, M. and Lucentini, M. and Majewski, S. and Monno, E. and Musico, P. and Santavenere, F. and T{\"o}dter, J. and Wegener, Hans-Peter and Ziemons, Karl},
  title     = {A novel TOF-PET MRI detector for diagnosis and follow up of the prostate cancer},
  series = {European Physical Journal Plus},
  volume    = {132},
  journal   = {European Physical Journal Plus},
  number    = {9},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2190-5444},
  doi       = {10.1140/epjp/i2017-11662-x},
  year      = {2017},
  language  = {en}
}
@article{ChoiFelderFelderetal.2020,
  author    = {Choi, Chang-Hoon and Felder, Tim and Felder, J{\"o}rg and Tellmann, Lutz and Hong, Suk-Min and Wegener, Hans-Peter and Shah, N Jon and Ziemons, Karl},
  title     = {Design, evaluation and comparison of endorectal coils for hybrid MR-PET imaging of the prostate},
  series = {Physics in Medicine \& Biology},
  volume    = {65},
  journal   = {Physics in Medicine \& Biology},
  number    = {11},
  publisher = {IOP},
  address   = {Bristol},
  issn      = {0031-9155},
  doi       = {10.1088/1361-6560/ab87f8},
  year      = {2020},
  abstract  = {Prostate cancer is one of the most common cancers among men and its early detection is critical for its successful treatment. The use of multimodal imaging, such as MR-PET, is most advantageous as it is able to provide detailed information about the prostate. However, as the human prostate is flexible and can move into different positions under external conditions, it is important to localise the focused region-of-interest using both MRI and PET under identical circumstances. In this work, we designed five commonly used linear and quadrature radiofrequency surface coils suitable for hybrid MR-PET use in endorectal applications. Due to the endorectal design and the shielded PET insert, the outer face of the coils investigated was curved and the region to be imaged was outside the volume of the coil. The tilting angles of the coils were varied with respect to the main magnetic field direction. This was done to approximate the various positions from which the prostate could be imaged. The transmit efficiencies and safety excitation efficiencies from simulations, together with the signal-to-noise ratios from the MR images were calculated and analysed. Overall, it was found that the overlapped loops driven in quadrature were superior to the other types of coils we tested. In order to determine the effect of the different coil designs on PET, transmission scans were carried out, and it was observed that the differences between attenuation maps with and without the coils were negligible. The findings of this work can provide useful guidance for the integration of such coil designs into MR-PET hybrid systems in the future.},
  language  = {en}
}
@inproceedings{OlderogMohrBegingetal.2021,
  author    = {Olderog, M. and Mohr, P. and Beging, Stefan and Tsoumpas, C. and Ziemons, Karl},
  title     = {Simulation study on the role of tissue-scattered events in improving sensitivity for a compact time of flight compton positron emission tomograph},
  series = {2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)},
  booktitle = {2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)},
  publisher = {IEEE},
  isbn      = {978-1-7281-7693-2},
  doi       = {10.1109/NSS/MIC42677.2020.9507901},
  pages     = {4 Seiten},
  year      = {2021},
  abstract  = {In positron emission tomography improving time, energy and spatial detector resolutions and using Compton kinematics introduces the possibility to reconstruct a radioactivity distribution image from scatter coincidences, thereby enhancing image quality. The number of single scattered coincidences alone is in the same order of magnitude as true coincidences. In this work, a compact Compton camera module based on monolithic scintillation material is investigated as a detector ring module. The detector interactions are simulated with Monte Carlo package GATE. The scattering angle inside the tissue is derived from the energy of the scattered photon, which results in a set of possible scattering trajectories or broken line of response. The Compton kinematics collimation reduces the number of solutions. Additionally, the time of flight information helps localize the position of the annihilation. One of the questions of this investigation is related to how the energy, spatial and temporal resolutions help confine the possible annihilation volume. A comparison of currently technically feasible detector resolutions (under laboratory conditions) demonstrates the influence on this annihilation volume and shows that energy and coincidence time resolution have a significant impact. An enhancement of the latter from 400 ps to 100 ps leads to a smaller annihilation volume of around 50\%, while a change of the energy resolution in the absorber layer from 12\% to 4.5\% results in a reduction of 60\%. The inclusion of single tissue-scattered data has the potential to increase the sensitivity of a scanner by a factor of 2 to 3 times. The concept can be further optimized and extended for multiple scatter coincidences and subsequently validated by a reconstruction algorithm.},
  language  = {en}
}
@article{PhilippEfthimiouPaganoetal.2022,
  author    = {Philipp, Mohr and Efthimiou, Nikos and Pagano, Fiammetta and Kratochwil, Nicolaus and Pizzichemi, Marco and Tsoumpas, Charalampos and Auffray, Etiennette and Ziemons, Karl},
  title     = {Image reconstruction analysis for positron emission tomography with heterostructured scintillators},
  series = {IEEE Transactions on Radiation and Plasma Medical Sciences},
  volume    = {7},
  journal   = {IEEE Transactions on Radiation and Plasma Medical Sciences},
  number    = {1},
  publisher = {IEEE},
  address   = {New York, NY},
  issn      = {2469-7311},
  doi       = {10.1109/TRPMS.2022.3208615},
  pages     = {41 -- 51},
  year      = {2022},
  abstract  = {The concept of structure engineering has been proposed for exploring the next generation of radiation detectors with improved performance. A TOF-PET geometry with heterostructured scintillators with a pixel size of 3.0×3.1×15 mm3 was simulated using Monte Carlo. The heterostructures consisted of alternating layers of BGO as a dense material with high stopping power and plastic (EJ232) as a fast light emitter. The detector time resolution was calculated as a function of the deposited and shared energy in both materials on an event-by-event basis. While sensitivity was reduced to 32\% for 100 μm thick plastic layers and 52\% for 50 μm, the CTR distribution improved to 204±49 ps and 220±41 ps respectively, compared to 276 ps that we considered for bulk BGO. The complex distribution of timing resolutions was accounted for in the reconstruction. We divided the events into three groups based on their CTR and modeled them with different Gaussian TOF kernels. On a NEMA IQ phantom, the heterostructures had better contrast recovery in early iterations. On the other hand, BGO achieved a better contrast to noise ratio (CNR) after the 15th iteration due to the higher sensitivity. The developed simulation and reconstruction methods constitute new tools for evaluating different detector designs with complex time responses.},
  language  = {en}
}