| 1. |
- Aykac, M., et al.
(författare)
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Timing performance of Hi-Rez detector for time-of-flight (TOF) PET
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 53:3, s. 1084-1089
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Tidskriftsartikel (refereegranskat)abstract
- Positron emission tomography (PET)-based on time-of-flight (TOF) is desired to enhance the image quality by improving the noise variance in the reconstruction. This benchtop study evaluates the timing performance of the current Hi-Rez detector which is based on a 13/spl times/13 LSO array of 4 mm/spl times/4 mm/spl times/20 mm crystals and not optimized for TOF PET applications. A Hamamatsu R9779, fast, 51-mm-diameter PMT was used for some experiments in this study as a reference PMT and its time resolution was measured to be 160 ps with a plastic scintillator. The average crystal time resolution of two Hi-Rez detectors, coupled to a 2/spl times/2 array of Hamamatsu 25-mm-diameter R8619 PMTs at +1050 V, in coincidence was measured to be 733 ps. The average crystal energy resolutions for two detectors were measured 13.1% and 13.2%. The average crystal time resolution of two Hi-Rez detectors improved from 733 ps to 642 ps when the PMT voltage was increased to +1300 V. The Hi-Rez detector was originally optimized for good energy resolution to reduce scatter and high packing fraction to obtain high sensitivity and improved spatial resolution for clinical PET.
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| 2. |
- Bauer, F., et al.
(författare)
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Dynode-Timing Method for PET Block Detectors
- 2008
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 55:1, s. 451-456
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Tidskriftsartikel (refereegranskat)abstract
- The focus of this paper is the investigation of a new dynode-timing technique optimized for PET block detectors. This method allows utilization of dynode signals from single but especially multiple photo-multiplier tubes (PMTs), operated with negative high-voltage. The technique will provide an event-timing trigger without deteriorating the anode signal. A printed circuit board has been developed and built for this investigation. Benchmark measurements have been performed, comparing timing of the anode signal with timing of the inverted last-dynode signal and timing of the dynode signal extracted via a newly developed LVPECL-logic based board. Timing measurements were performed with plastic as well as LSO scintillators. From single PMT measurements we find a 30 ps improvement with the dynode-timing method compared to the standard anode timing with two Photonis XP2020Q PMTs with LSO (10 mmtimes10 mmtimes10 mm). For a quad-PMT block detector, assembled of four Hamamatsu R9800 with a Hi-Rez block, the timing-resolution improves ~10%, by 43 ps compared to the standard anode timing.
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| 3. |
- Bauer, F., et al.
(författare)
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Performance Study of the New Hamamatsu R9779 and Photonis XP20D0 Fast 2" Photomultipliers
- 2007
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 54:3, s. 422-426
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Tidskriftsartikel (refereegranskat)abstract
- The focus of this paper is the evaluation of the new fast 51 mm-diameter, 8-stage Hamamatsu R9779 photomultipliers (PMTs) with an acceleration-ring at the front-end and the Photonis XP20D0 PMTs with a screening grid in front of the anode. The following performance characteristics are presented: Timing resolution, anode-scan-uniformity and transit-time spread. The unfolded timing resolution for two R9779 was 192 ps and 210 ps using plastic scintillators. The individual timing resolutions for two XP20D0 using plastic scintillators are 181 ps and 154 ps, respectively. The variation in time resolution across the windows of the two R9779 ranged between 117 ps and 171 ps, and 79 ps and 73 ps for the two XP20D0 PMTs.
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| 4. |
- Eriksson, L, et al.
(författare)
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An investigation of sensitivity limits in PET scanners
- 2007
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Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : Elsevier BV. - 0168-9002. ; 580:2, s. 836-842
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Melcher, C., et al.
(författare)
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Current and Future Use of LSO:Ce Scintillators in PET
- 2006
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Ingår i: Radiation detectors for medical applications. - Dordrecht : Springer. - 9781402050916 ; , s. 243-257
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Konferensbidrag (refereegranskat)abstract
- Single crystal scintillators of Lu2SiO5:Ce (LSO:Ce) were first developed about 15 years ago and have been in commercial use in positron emission tomography systems for more than five years. Annual production now exceeds 10,000 kg. We review the development of LSO:Ce and its implementation in PET, and summarize the current understanding of the scintillation characteristics and mechanisms. In addition, we present the evolution of LSO:Ce detector design and consider the potential performance of future imaging systems. In particular, coincidence timing measurements are presented and time-of-flight systems that take better advantage of the timing characteristics of LSO:Ce are discussed.
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| 6. |
- Bauer, F., et al.
(författare)
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Measurements and Ray-Tracing Simulations of Light Spread in LSO Crystals
- 2009
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 56:5, s. 2566-2573
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Tidskriftsartikel (refereegranskat)abstract
- We report on measurements of the absolute light output from LSO crystals for irradiation with 511 keV gamma rays as a function of interaction position, reflector arrangement, detector coupling geometry and optical coupling to an adjacent crystal. The light output for this series of geometrical configurations is simulated with the ZEMAX ray-tracing software. By fine-tuning the optical parameters of the bulk and at the interfaces of the crystal, a model is obtained which yields good agreement with experimental data for all configurations. The resulting parameter set is applied to calculate the light distribution in a 12$,times,$ 12 crystal block detector. A comparison of measured and calculated block position profiles shows good agreement, demonstrating the potential of the simulation model to predict block detector performance data and provide guidelines for future array designs.
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