TY  - CHAP
A1  - Peters, H.
A1  - Ziemons, Karl
A1  - Dammers, J.
A1  - Müller-Veggian, Mattea
ED  - Nenonen, Jukka
T1  - Continuous head motion detection during MEG measurement using head location coils
T2  - Proceedings of the 12th International Conference on Biomagnetism : August 13 - 17, 2000, Helsinki University of Technology, Espoo, Finland
Y1  - 2001
SN  - 951-22-5401-8
N1  - Biomag <12, 2000, Espoo> ; Teknillinen Korkeakoulu <Helsinki> ; International Conference on Biomagnetism <12, 2000, Espoo>
PB  - Helsinki Univ. of Technology, Laboratory of Biomedical Engineering
CY  - Espoo
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Chavan, U.
A1  - Lame, H.
A1  - Parl, C.
A1  - Müller-Veggian, Mattea
A1  - Ziemons, Karl
T1  - Treating the Gain Non-Uniformity of Multi Channel PMTs by Channel-Specific Trigger Levels
JF  - 2006 IEEE Nuclear Science Symposium Conference Record, Vol. 2.
Y1  - 2006
SN  - 1082-3654
SP  - 1301
EP  - 1304
CY  - San Diego, CA
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Achten, R.
A1  - Auffray, E.
A1  - Müller-Veggian, Mattea
T1  - The ClearPET™ neuro scanner: a dedicated LSO/LuYAP phoswich small animal PET scanner
JF  - 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
Y1  - 2004
SN  - 1082-3654
N1  - Nuclear Science Symposium Conference Record, 2004 IEEE
SP  - 2430
EP  - 2433
PB  - IEEE Operations Center
CY  - Piscataway, NJ
ER  - 
TY  - JOUR
A1  - Boecker, Henning
A1  - Kuwert, Torsten
A1  - Langen, Karl-J.
A1  - Lange, Herwig W.
A1  - Czech, Norbert
A1  - Ziemons, Karl
A1  - Herzog, Hans
A1  - Shikare, Shekar
A1  - Weindl, Anton
A1  - Feinendegen, Ludwig E.
T1  - SPECT with HMPAO compared to PET with FDG in Huntington disease
JF  - Journal of Computer Assisted Tomography
Y1  - 1994
SN  - 1532-3145
VL  - 18
IS  - 4
SP  - 542
EP  - 548
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Kleines, H.
A1  - Erken, I.
A1  - Knoben, J.
A1  - Zwoll, K.
ED  - Lehmann, Thomas
T1  - IME-DV Projekt: M-FIRBe, Multi-Modality Functional Imaging for Brain Research
JF  - Bildverarbeitung für die Medizin : Algorithmen - Systeme - Anwendungen
Y1  - 1997
SN  - 3-86073-519-5
N1  - Proceedings des Aachener Workshops am 8. u. 9. November 1996 ; WG_005 Arbeitsgruppenvorstellungen
SP  - 363
EP  - 366
PB  - Verl. der. Augustinus-Buchh.
CY  - Aachen
ER  - 
TY  - JOUR
A1  - Kleines, H.
A1  - Erki, I.
A1  - Ziemons, Karl
A1  - Zwoll, K.
ED  - Lehmann, Thomas
T1  - ATM- und Multimedia Pilotsystem im Rahmen des Projektes M-FIBRe Aufbau und Erfahrungen
JF  - Bildverarbeitung für die Medizin : Algorithmen - Systeme - Anwendungen
Y1  - 1997
SN  - 3-86073-519-5
N1  - Proceedings des Aachener Workshops am 8. u. 9. November 1996 ; PP_001 Posterpräsentation
SP  - 241
EP  - 248
PB  - Verl. der. Augustinus-Buchh.
CY  - Aachen
ER  - 
TY  - JOUR
A1  - Erki, I.
A1  - Kleines, H.
A1  - Ziemons, Karl
A1  - Zwoll, K.
ED  - Lehmann, Thomas
T1  - Interaktives System zur Darstellung funktionaler Bilddaten
JF  - Bildverarbeitung für die Medizin : Algorithmen - Systeme - Anwendungen
Y1  - 1997
SN  - 3-86073-519-5
N1  - Proceedings des Aachener Workshops am 8. u. 9. November 1996 ; PP_002 Posterpräsentation
SP  - 249
EP  - 254
PB  - Verl. der. Augustinus-Buchh.
CY  - Aachen
ER  - 
TY  - JOUR
A1  - Grießmeier, M.
A1  - Sonnenberg, F.
A1  - Weckesser, M.
A1  - Ziemons, Karl
A1  - Langen, K.-J.
A1  - Müller-Gärtner, H. W.
T1  - Improvement of SPECT quantification in small brain structures by using experiment based recovery-coefficient corrections
JF  - European Journal of Nuclear Medicine
Y1  - 1996
SN  - 1619-7089
N1  - Abstracts ; PSu827
VL  - 23
IS  - 9
SP  - 1238
EP  - 1238
ER  - 
TY  - JOUR
A1  - Langen, Karl J.
A1  - Ziemons, Karl
A1  - Kiwit, Jürgen C. W.
A1  - Herzog, Hans
A1  - Kuwert, Torsten
A1  - Bock, Wolfgang
A1  - Stöcklin, Gerhard
A1  - Feinendegen, Ludwig E.
A1  - Müller-Gärtner, Hans-W.
T1  - 3-[123I]iodo-α-methyltyrosine and [methyl-11C]-L-methionine uptake in cerebral gliomas: a compara-tive study using SPECT and PET
JF  - Journal of Nuclear Medicine
Y1  - 1997
SN  - 0161-5505
VL  - 38
IS  - 4
SP  - 517
EP  - 522
ER  - 
TY  - JOUR
A1  - Weckesser, Matthias
A1  - Hufnagel, Andreas
A1  - Ziemons, Karl
A1  - Grießmeier, Martin
A1  - Sonnenberg, Frank
A1  - Hackländer, Thomas
A1  - Langen, Karl-J.
A1  - Holschbach, Markus
A1  - Elger, Christian E.
A1  - Müller-Gärtner, Hans-W.
T1  - Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy
JF  - European Journal of Nuclear Medicine
N2  - 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.
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1156
EP  - 1161
ER  - 
TY  - JOUR
A1  - Schmidt, Daniela
A1  - Langen, Karl-J.
A1  - Herzog, Hans
A1  - Wirths, Jochen
A1  - Holschbach, Markus
A1  - Kiwit, Jürgen C. W.
A1  - Ziemons, Karl
A1  - Coenen, Heinz-H.
A1  - Müller-Gärtner, Hans-W.
T1  - Whole-body kinetics and dosimetry of L-3[123I]-iodo-α-methyltyrosine
JF  - European Journal of Nuclear Medicine
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1162
EP  - 1166
ER  - 
TY  - JOUR
A1  - Weckesser, Martin
A1  - Grießmeier, Martin
A1  - Schmidt, Daniela
A1  - Sonnenberg, Frank
A1  - Ziemons, Karl
A1  - Kemna, Lars
A1  - Holschbach, Marcus
A1  - Langen, Karl-J.
A1  - Müller-Gärtner, Hans-W.
T1  - Iodine-123 α-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent
JF  - European Journal of Nuclear Medicine
N2  - 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.
Y1  - 1998
SN  - 1619-7089
VL  - 25
IS  - 2
SP  - 150
EP  - 156
ER  - 
TY  - JOUR
A1  - Taylor, J. G.
A1  - Schmitz, N.
A1  - Ziemons, Karl
A1  - Grosse-Ruyken, M.-L.
A1  - Gruber, O.
A1  - Müller-Gärtner, H.-W.
A1  - Shah, N. J.
T1  - The network of brain areas involved in the motion aftereffect
JF  - Neuroimage
N2  - 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.
Y1  - 2000
SN  - 1053-8119
VL  - 11
IS  - 4
SP  - 257
EP  - 270
ER  - 
TY  - JOUR
A1  - Fink, G. R.
A1  - Marshall, J. C.
A1  - Shah, N. J.
A1  - Weiss, P.H.
A1  - Halligan, P. W.
A1  - Grosse-Ruyken, M.
A1  - Ziemons, Karl
A1  - Zilles, K.
A1  - Freund, H. J.
T1  - Line bisection judgments implicate right parietal cortex and cerebellum as assessed by fMRI
JF  - Neurology
Y1  - 2000
SN  - 1526-632X
VL  - 54
IS  - 6
SP  - 1324
EP  - 1331
ER  - 
TY  - JOUR
A1  - Bussmann, N.
A1  - Engels, R.
A1  - Fuss, L.
A1  - Kemmerling, G.
A1  - Reinartz, R.
A1  - Langen, K.-J.
A1  - Schelten, J.
A1  - Ziemons, Karl
T1  - Performance measurement of a new high resolution detector system for I-131 thyroid studies
JF  - 2000 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - 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
Y1  - 2000
SN  - 1082-3654
SP  - 22/35
EP  - 22/37
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse recording by free-running sampling
JF  - 2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2
N2  - 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
Y1  - 2000
SN  - 1082-3654
SP  - 9/179
EP  - 9/181
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse recording by free-running sampling
JF  - IEEE Transactions on Nuclear Science
N2  - 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
Y1  - 2001
SN  - 0018-9499
VL  - 48
IS  - 3
SP  - 524
EP  - 526
ER  - 
TY  - JOUR
A1  - Heinrich, U.
A1  - Blum, A.
A1  - Bussmann, N.
A1  - Engels, R.
A1  - Kemmerling, G.
A1  - Weber, S.
A1  - Ziemons, Karl
T1  - Statistical studies on the light output and energy resolution of small LSO single crystals with different surface treatments combined with various reflector materials
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - 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.
Y1  - 2002
SN  - 0168-9002
N1  - Proceedings of the 6th International Conference on Inorganic Scin tillators and their Use in Scientific and Industrial Applications
VL  - 486
IS  - 1-2
SP  - 60
EP  - 66
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - A PET system with free running ADCs
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - 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.
Y1  - 2002
SN  - 0168-9002
N1  - Proceedings of the 6th International Conference on Inorganic Scin tillators and their Use in Scientific and Industrial Applications
VL  - 486
IS  - 1-2
SP  - 18
EP  - 21
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Coincidence detection by digital processing of free-running sampled pulses
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - 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.
Y1  - 2002
SN  - 0168-9002
VL  - 487
IS  - 3
SP  - 530
EP  - 534
ER  -