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See detailPerformance evaluation of the General Electric eXplore CT 120 micro-CT using the vmCT phantom.
Bahri, Mohamed Ali ULg; Warnock, Geoffrey ULg; Plenevaux, Alain ULg et al

in Nuclear Instruments & Methods in Physics Research Section A (2011), 648

The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high power tube and a flat panel detector. It allows high resolution and high contrast fast CT scanning of ... [more ▼]

The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high power tube and a flat panel detector. It allows high resolution and high contrast fast CT scanning of small animals. The aim of this study was to compare the performance of the eXplore CT 120 with the one of the eXplore Ultra, its predecessor for which the methodology using the vmCT phantom was already described [1]. The phantom was imaged using typical rat (fast scan or F) or mouse (in vivo bone scan or H) scanning protocols. With the slanted edge method, a 10% modulation transfer function (MTF) was observed at 4.4 (F) and 3.9-4.4 (H) mm-1 corresponding to 114 μm resolution. A fairly larger MTF was obtained with the coil method with the MTF for the thinnest coil (3.3 mm-1 ) equal to 0.32 (F) and 0.34 (H). The geometric accuracy was better than 0.3%. There was a highly linear (R2 > 0.999) relationship between measured and expected CT numbers for both the CT number accuracy and linearity sections of the phantom. A cupping effect was clearly seen on the uniform slices and the uniformity-to-noise ratio ranged from 0.52 (F) to 0.89 (H). The air CT number depended on the amount of polycarbonate surrounding the area where it was measured: a difference as high as approximately 200 HU was observed. This hindered the calibration of this scanner in HU. This is likely due to the absence of corrections for beam hardening and scatter in the reconstruction software. However in view of the high linearity of the system, the implementation of these corrections would allow a good quality calibration of the scanner in HU. In conclusion, the eXplore CT 120 achieved a better spatial resolution than the eXplore Ultra (based on previously reported specifications) and future software developments to include beam hardening and scatter corrections will make the new generation CT scanner even more promising. [less ▲]

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See detailNEMA NU1-2001 performance tests of four Philips Brightview cameras
Seret, Alain ULg

in Nuclear Instruments & Methods in Physics Research Section A (2011), 648(Supplement 1), 89-92

The Brightview is the latest generation dual-head SPECT and SPECT-CT camera from Philips. It is equipped with two large field of view g-ray digital Anger detectors and with an X-ray flat panel detector ... [more ▼]

The Brightview is the latest generation dual-head SPECT and SPECT-CT camera from Philips. It is equipped with two large field of view g-ray digital Anger detectors and with an X-ray flat panel detector. All primary and some secondary NEMA NU1-2001 performance tests were conducted on four (two SPECT and two SPECT-CT) recently installed Brightview systems mainly with 99mTc and low energy high resolution (LEHR) collimators. Intrinsic uniformity for four other isotopes (67Ga, 123I, 131I, 111In) and system uniformity with medium (ME) and high (HE) energy collimators were also measured. The measured parameters were almost identical for all the tested systems and the vast majority of measurements were within the manufacturer’s specifications. The only exception was some of the uniformity indexes of two of the heads but a new calibration solved that particular problem. System alignment could not be processed using the NEMA performance tests due to a file writing problem when performing 360° rotation for each head. However, the Philips COR test was conducted and found to be satisfactory. [less ▲]

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See detailNeutrinos from photo-hadronic interactions in Pks2155-304
Becker, J.; Meli, Athina ULg; Biermann, Peter

in Nuclear Instruments & Methods in Physics Research Section A (2011)

The high-peaked BL Lac object Pks2155-304 shows high variability at multiwavelengths, i.e. from optical up to TeV energies. A giant flare of around 1 h at X-ray and TeV energies was observed in 2006 [1 ... [more ▼]

The high-peaked BL Lac object Pks2155-304 shows high variability at multiwavelengths, i.e. from optical up to TeV energies. A giant flare of around 1 h at X-ray and TeV energies was observed in 2006 [1]. In this context, it is essential to understand the physical processes in terms of the primary spectrum and the radiation emitted, since high-energy emission can arise in both leptonic and hadronic processes. In this contribution, we investigate the possibility of neutrino production in photo-hadronic interactions. In particular, we predict a direct correlation between optical and TeV energies at sufficiently high optical radiation fields. We show that in the blazar Pks2155-304, the optical emission in the low-state is sufficient to lead to photo-hadronic interactions and therefore to the production of high-energy photons. [less ▲]

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See detailActive Galactic Nuclei and Gamma Ray Bursts: Relativistic shocks and the origin of ultra high energy cosmic rays
Meli, Athina ULg; Becker, J. K.; Quenby, J, J,

in Nuclear Instruments & Methods in Physics Research Section A (2011)

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See detailIonoluminescence of diamond, synthetic diamond and simulants
Calvo Del Castillo, Helena ULg; Ruvalcaba Sil, Jose Luis; Álvarez, M A[ et al

in Nuclear Instruments & Methods in Physics Research Section A (2007), 387

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