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S Beer,
M Streun,
T Hombach,
J Buehler,
S Jahnke,
M Khodaverdi, H Larue,
S Minwuyelet,
C Parl,
G Roeb,
U Schurr,
K Ziemons
[show abstract]
[hide abstract]
ABSTRACT: Positron emitters such as (11)C, (13)N and (18)F 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 (11)CO(2) 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.
Physics in Medicine and Biology 02/2010; 55(3):635-46. · 2.83 Impact Factor
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[show abstract]
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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.
Nuclear Science Symposium Conference Record (NSS/MIC), 2009 IEEE; 12/2009
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Nuclear Science Symposium Conference Record, 2006. IEEE, San Diego; 10/2006
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[show abstract]
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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 Jülich (ClearPET Neuro) is equipped with 10240 crystals on 80 PMTs. The paper will present an overview of the data acquisition system.
IEEE Transactions on Nuclear Science 07/2006; · 1.45 Impact Factor
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E. Auffray,
M. Boutemeur,
G. Brandenburg,
P. Bruyndonckx,
Y. Choi,
Y. D’Asseler,
O. Devroede,
O. Dietzel,
C. Dujardin,
A. Fedorov, [......],
J. Trummer,
S. Vandenberghe,
R. Van Holen,
J.-M. Vieira,
S. Weber,
E. Wieörs,
M. Wisniewska,
D. Wisniewski,
Y. Wu,
K. Ziemons
[show abstract]
[hide abstract]
ABSTRACT: The Crystal Clear Collaboration has designed and built a family of high resolution small animal PET scanners. These were designed
to be used in research laboratories and provide maximum modularity and flexibility. The source code of the data acquisition
and reconstruction software is freely available to the users. The design is based on the use of the Hamamatsu R7600-M64 multi-anode
photomultiplier tube and an LSO/LuYAP phoswich matrix with one-to-one coupling between the crystals and the photo-detector.
A complete system has 80 PMT tubes in four rings with a minimum inner diameter of 137 mm and an axial field of view of 110
mm. The detectors are rotating over 360 degrees so that partially filled ring geometries can be used. This greatly simplifies
the combination of PET with other imaging modalities. Single gamma interactions are recorded in list mode format and coincidences
are found by software.
03/2006: pages 149-164;
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M. Khodaverdi,
S. Weber,
M. Streun,
Ch. Parl, H. Larue,
G. Brandenburg,
A. Bauer,
M. Dehnhardt,
E. Auffray,
M. Boutemeur, [......],
S. Tavernier,
J. Trummer,
R. Van Holen,
J.-M. Vieira,
E. Wieers,
M. Wisniewska,
D. Wisniewski,
Y. Wu,
U. Pietrzyk,
K. Ziemons
[show abstract]
[hide abstract]
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.
Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
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[show abstract]
[hide abstract]
ABSTRACT: The small animal PET scanners developed by the Crystal Clear Collaboration (ClearPET™) 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.
Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
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[show abstract]
[hide abstract]
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 Julich (ClearPET™ Neuro) is equipped with 10240 crystals on 80 PMTs. The paper presents an overview of the data acquisition system.
Real Time Conference, 2005. 14th IEEE-NPSS; 07/2005
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K. Ziemons,
R. Achten,
E. Auffray,
A. Bauer,
G. Brandenburg,
P. Bruyndonckx,
Y. Choi,
J. Daemen,
M. Dehnhardt,
O. Devroede, [......],
U. Pietrzyk,
J. Schmitz,
M. Streun,
S. Tavernier,
M. Veggian,
E. Zimmermann,
H.H. Coenen,
H. Halling,
R. Sievering,
K. Zilles
[show abstract]
[hide abstract]
ABSTRACT: The ClearPET initiative is a project being undertaken by working groups of the Crystal Clear Collaboration (CCC). Its aim is to develop a second-generation high performance small animal positron emission tomograph. The ClearPET™ camera is expected to provide both high sensitivity and high spatial resolution. It uses a phoswich arranging combining two types of lutetium-based scintillator materials: LSO and LuYAP:Ce. Based on the same detector modules different designs from each collaboration partner are realized for their associated medical institutes. Each dedicated version is expressed by the name ClearPET™ plus an extension. The ClearPET™ neuro scanner is a dedicated small animal scanner to allow measurements of signal transduction in non-human primates under physiological conditions. This scanner is build by working groups of the Research Center Julich (FZJ). The gantry allows rotation of the detector modules as well as tilting by 90 degrees to measure non-human primates in an upright sitting position. The opening diameter of the ring is variable between 130 mm and 300 mm, the axial detector length is 110 mm.
Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
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[show abstract]
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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.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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[show abstract]
[hide abstract]
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.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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K. Ziemons,
E. Auffray,
R. Barbier,
G. Brandenburg,
P. Bruyndonckx,
Y. Choi,
D. Christ,
N. Costes,
Y. Declais,
O. Devroede, [......],
Ch. Pedrini,
A.G. Petrosyan,
U. Pietrzyk,
M. Rey,
S. Saladino,
D. Sappey-Marinier,
L. Simon,
M. Streun,
S. Tavernier,
J.M. Vieira
[show abstract]
[hide abstract]
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 mm<sup>3</sup>) 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.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
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[show abstract]
[hide abstract]
ABSTRACT: We present our results on the development and characterization of a prototype of Hilbert spectrometer, which is intended to operate with pulsed far-infrared radiation. The new prototype consists of high-T<sub>c</sub> Josephson detector in an optical cryostat, analog electronics with the bandwidth of 14 MHz, and a DSP-based data acquisition system, controlling spectroscopic measurements. The specially developed digital data acquisition system gives a possibility to operate in two regimes - with and without integration of the pulsed signal. The tests have been carried out using pulsed 94 GHz radiation with pulse duration of 200 ns and a pulse repetition rate of 1 MHz. A measuring time of 7 ms for a data set of 512 spectral points has been realized. It has been demonstrated, that in a broadband (≈10 MHz) regime of measurements without integration the developed spectrometer has a dynamic range of external signal power of 17 dB, which can be enhanced by using integration function.
IEEE Transactions on Appiled Superconductivity 07/2003; · 1.04 Impact Factor
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[show abstract]
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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.
IEEE Transactions on Nuclear Science 07/2003; · 1.45 Impact Factor
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[show abstract]
[hide abstract]
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.
Nuclear Science Symposium Conference Record, 2002 IEEE; 12/2002
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[show abstract]
[hide abstract]
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.
Nuclear Science Symposium Conference Record, 2001 IEEE; 12/2001
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[show abstract]
[hide abstract]
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
Nuclear Science Symposium Conference Record, 2000 IEEE; 02/2000
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[show abstract]
[hide abstract]
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 . 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 .
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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M. Streun,
S. Beer,
T. Hombach,
S. Jahnke,
M. Khodaverdi, H. Larue,
S. Minwuyelet,
C. Pari,
G. Roeb,
U. Schurr,
K. Ziemons
[show abstract]
[hide abstract]
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 <sup>11</sup>C distribution within a plant while or after assimilation of <sup>11</sup>CO<sub>2</sub>. Front end electronics and data acquisition architecture of the scanner are based on the ClearPET<sup>TM</sup> 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 <sup>11</sup>C (20 min). As a result the count rates can vary over a wide range and accurate dead time correction is necessary.
Nuclear Science Symposium Conference Record, 2007. NSS '07. IEEE;
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K. Ziemons,
E. Auffray,
R. Barbier,
G. Brandenburg,
P. Bruyndonckx,
Y. Choi,
D. Christ,
N. Costes,
Y. Declais,
O. Devroede, [......],
Ch. Pedrini,
A.G. Petrosyan,
U. Pietrzyk,
M. Rey,
S. Saladino,
D. Sappey-Marinier,
L. Simon,
M. Streun,
S. Tavernier,
J.M. Vieira
[show abstract]
[hide abstract]
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.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
