TY - JOUR A1 - Streun, M. A1 - Brandenburg, G. A1 - Khodaverdi, M. A1 - Larue, H. A1 - Parl, C. A1 - Ziemons, Karl T1 - Timemark correction for the ClearPET™ scanners JF - 2005 IEEE Nuclear Science Symposium Conference Record, Vol. 4 N2 - 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 Y1 - 2006 SN - 1082-3654 SP - 2057 EP - 2060 ER - TY - JOUR A1 - Mosset, J.-B. A1 - Devroede, O. A1 - Krieguer, M. A1 - Rey, M. A1 - Vieira, J.-M. A1 - Jung, J. H. A1 - Kuntner, C. A1 - Streun, M. A1 - Ziemons, Karl A1 - Auffray, E. A1 - Sempere-Roldan, P. A1 - Lecoq, P. A1 - Bruyndonckx, P. A1 - Loude, J.-F. A1 - Tavernier, S. A1 - Morcel, C. T1 - Development of an optimized LSO/LuYAP phoswich detector head for the Lausanne ClearPET demonstrator JF - IEEE Transactions on Nuclear Science N2 - 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. Y1 - 2006 SN - 0018-9499 VL - 53 IS - 1 SP - 25 EP - 29 ER - TY - GEN A1 - Rongen, Heinz A1 - Ziemons, Karl A1 - Schiek, Michael A1 - Tass, Alexander T1 - Vorrichtung zur Messung biomedizinischer Daten eines Probanden und Verfahren zur Simulation des Probanden mit in Echtzeit verarbeiteten Daten T1 - Device for measuring biomedical data from a testee and method for stimulating the testee with data processed in real-time N2 - 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 Übertragung der Daten vom Messsystem zur ersten Hardware-Komponente zur Aufzeichnung der Daten ist erfindungsgemäss ein Mittel zur galvanischen Auftrennung der Daten angeordnet. Auf diese Weise ist wenigstens die Duplizierung der Daten für Datenverarbeitungszwecke gewährleistet. Die auf diese Weise verarbeiteten Daten werden für ein Verfahren zur Echtzeit-Stimulation eines Probanden genutzt. Y1 - 2006 N1 - Auch veröffentlicht als EP2007276 ; US2009069662 ; US8301222 ; JP2009535071 ; WO2007118443 ; AT 533401 SP - 1 EP - 12 ER - TY - JOUR A1 - Streun, M. A1 - Beer, S. A1 - Hombach, T. 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 - PlanTIS: A positron emission tomograph for imaging 11C transport in plants JF - 2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6 N2 - 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. Y1 - 2008 SN - 1082-3654 SP - 4110 EP - 4112 ER - TY - JOUR A1 - Ziemons, Karl A1 - Bruyndonckx, P. A1 - Perez, J. M. A1 - Pietrzyk, U. A1 - Rato, P. A1 - Tavernier, S. T1 - Beyond ClearPET: Next Aims JF - 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008 N2 - 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. Y1 - 2008 SN - 978-1-4244-2003-2 SP - 1421 EP - 1424 ER - TY - JOUR A1 - Jahnke, Siegfried A1 - Menzel, Marion I. A1 - Dusschoten, Dagmar van A1 - Roeb, Gerhard W. A1 - Bühler, Jonas A1 - Minwuyelet, Senay A1 - Blümler, Peter A1 - Temperton, Vicky M. A1 - Hombach, Thomas A1 - Streun, Matthias A1 - Beer, Simone A1 - Khodaverdi, Maryam A1 - Ziemons, Karl A1 - Coenen, Heinz H. A1 - Schurr, Ulrich T1 - Combined MRI–PET dissects dynamic changes in plant structures and functions JF - The Plant Journal N2 - 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. Y1 - 2009 SN - 1365-313X VL - 59 IS - 4 SP - 634 EP - 644 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Wedrowski, M. A1 - Bruyndonckx, P. A1 - Tavernier, S. A1 - Zhi, L. A1 - Dang, J. A1 - Mendes, P. R. A1 - Perez, J. M. A1 - Ziemons, Karl T1 - Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography JF - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) N2 - 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 × 20 × 10 mm3 monolithic LSO crystal block. Y1 - 2009 SN - 1082-3654 SP - 2625 EP - 2628 ER - TY - JOUR A1 - Streun, M. A1 - Larue, H. A1 - Parl, C. A1 - Ziemons, Karl T1 - A compact PET detector readout using charge-to-time conversion JF - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) N2 - 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. Y1 - 2009 SN - 1082-3654 SP - 1868 EP - 1870 PB - IEEE CY - New York 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 - http://dx.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 - 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 - http://dx.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 -