TY - JOUR A1 - Christ, D. A1 - Hollendung, A. A1 - Larue, H. A1 - Parl, C. A1 - Streun, M. A1 - Weber, S. A1 - Ziemons, Karl A1 - Halling, H. T1 - Homogenization of the MultiChannel PM gain by inserting light attenuating masks JF - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4 N2 - 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. Y1 - 2004 SN - 1082-3654 SP - 2382 EP - 2385 ER - TY - JOUR A1 - Ziemons, Karl A1 - Heinrichs, U. A1 - Streun, M. A1 - Pietrzyk, U. T1 - Validation of GEANT3 simulation studies with a dual-head PMT ClearPET™ prototype JF - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5 N2 - 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. Y1 - 2004 SN - 1082-3654 SP - 3053 EP - 3056 ER - TY - JOUR A1 - Auffray, E. A1 - Bruyndonckx, P. A1 - Devroede, O. A1 - Fedorov, A. A1 - Ziemons, Karl T1 - The ClearPET project JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - 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. Y1 - 2004 SN - 0168-9002 N1 - Proceedings of the 2nd International Conference on Imaging Technologies in Biomedical Sciences VL - 527 IS - 1-2 SP - 171 EP - 174 ER - TY - JOUR A1 - Streun, M. A1 - Christ, D. A1 - Hellendung, A. A1 - Larue, H. A1 - Ziemons, Karl A1 - Halling, H. T1 - Effects of crosstalk and gain nonuniformity using multichannel PMTs in the Clearpet® scanner JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - 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. Y1 - 2005 SN - 0168-9002 N1 - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications VL - 537 IS - 1-2 SP - 402 EP - 405 ER - TY - JOUR A1 - Ziemons, Karl A1 - Auffray, E. A1 - Barbier, R. A1 - Brandenburg, G. A1 - Bruyndonckx, P. T1 - The ClearPET™ project: Development of a 2nd generation high-performance small animal PET scanner JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - 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. Y1 - 2005 SN - 0168-9002 N1 - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications VL - 537 IS - 1-2 SP - 307 EP - 311 ER - TY - JOUR A1 - Beer, S. A1 - Streun, M. A1 - Hombach, T. A1 - Buehler, J. A1 - Jahnke, S. A1 - Khodaverdi, M. A1 - Larue, H. A1 - Minwuyelet, S. A1 - Parl, C. A1 - Roeb, G. A1 - Schurr, U. A1 - Ziemons, Karl T1 - Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants JF - Physics in Medicine and Biology N2 - 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. Y1 - 2010 U6 - https://doi.org/10.1088/0031-9155/55/3/006 SN - 1361-6560 VL - 55 IS - 3 SP - 635 EP - 646 PB - IOP CY - Bristol ER - TY - JOUR A1 - Herzog, Hans A1 - Pietrzyk, Uwe A1 - Shah, N. Jon A1 - Ziemons, Karl T1 - The current state, challenges and perspectives of MR-PET JF - Neuroimage N2 - 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 Jülich, 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. Y1 - 2010 U6 - https://doi.org/10.1016/j.neuroimage.2009.10.036 SN - 1053-8119 VL - 49 IS - 3 SP - 2072 EP - 2082 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Parl, C. A1 - Larue, H. A1 - Streun, M. A1 - Ziemons, Karl T1 - Double-side-readout technique for SiPM-matrices JF - 2010 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) N2 - 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. Y1 - 2011 SN - 1095-7863 SP - 1486 EP - 1487 PB - IEEE CY - New York ER - TY - CHAP A1 - Streun, M. A1 - Al-Kaddoum, R. A1 - Parl, C. A1 - Pietrzyk, U. A1 - Ziemons, Karl A1 - Waasen, S. van T1 - Simulation studies of optical photons in monolithic block scintillators T2 - 2011 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) N2 - 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. Y1 - 2012 SN - 978-1-4673-0120-6 (electronic ISBN) SN - 978-1-4673-0118-3 (print ISBN) U6 - https://doi.org/10.1109/NSSMIC.2011.6154621 SP - 1380 EP - 1382 PB - IEEE CY - New York ER - TY - GEN A1 - Achten, Richard A1 - Bauer, Andreas A1 - Bertram, Walter A1 - Cremer, Markus A1 - Daemen, Jos A1 - Dehnhardt, Markus A1 - Fleischer, Manfred A1 - Kirchner, Peter A1 - Leyendecker, Marco A1 - Pietrzyk, Uwe A1 - Schmitz, Jakob A1 - Ziemons, Karl A1 - Zilles, Karl T1 - Vorrichtung zum Halten eines lebenden Objektes bei physiologischen Messungen N2 - 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 Mundstück aufweisen, das mit einer Aussparung für die Zähne des Lebewesens versehen ist, mit einem Masseanteil von wenigstens 95% an glasfaserverstärktem Kunststoff. Y1 - 2005 N1 - Patent Anmelder : Forschungszentrum Jülich GmbH SP - 1 EP - 17 ER -