The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Guillem Pratx - One of the best experts on this subject based on the ideXlab platform.
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single cell radioluminescence microscopy with two fold higher sensitivity using dual scintillator configuration
PLOS ONE, 2020Co-Authors: Tae Jin Kim, Qian Wang, Mark Shelor, Guillem PratxAbstract:Radioluminescence microscopy (RLM) is an imaging technique that allows quantitative analysis of clinical radiolabeled drugs and probes in single cells. However, the modality suffers from slow data acquisition (15–30 minutes), thus critically affecting experiments with short-lived radioactive drugs. To overcome this issue, we suggest an approach that significantly accelerates data collection. Instead of using a single scintillator to image the decay of radioactive molecules, we sandwiched the radiolabeled cells between two Scintillators. As proof of concept, we imaged cells labeled with [18F]FDG, a radioactive glucose popularly used in oncology to image tumors. Results show that the double scintillator configuration increases the microscope sensitivity by two-fold, thus reducing the image acquisition time by half to achieve the same result as the single scintillator approach. The experimental results were also compared with Geant4 Monte Carlo simulation to confirm the two-fold increase in sensitivity with only minor degradation in spatial resolution. Overall, these findings suggest that the double scintillator configuration can be used to perform time-sensitive studies such as cell pharmacokinetics or cell uptake of short-lived radiotracers.
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bright lu2o3 eu thin film Scintillators for high resolution radioluminescence microscopy
Advanced Healthcare Materials, 2015Co-Authors: Debanti Sengupta, Stuart R. Miller, Zsolt Marton, Frederick T. Chin, Vivek V. Nagarkar, Guillem PratxAbstract:The performance of a new thin-film Lu2O3:Eu scintillator for single-cell radionuclide imaging is investigated. Imaging the metabolic properties of heterogeneous cell populations in real time is an important challenge with clinical implications. An innovative technique called radioluminescence microscopy has been developed to quantitatively and sensitively measure radionuclide uptake in single cells. The most important component of this technique is the scintillator, which converts the energy released during radioactive decay into luminescent signals. The sensitivity and spatial resolution of the imaging system depend critically on the characteristics of the scintillator, that is, the material used and its geometrical configuration. Scintillators fabricated using conventional methods are relatively thick and therefore do not provide optimal spatial resolution. A thin-film Lu2O3:Eu scintillator is compared to a conventional 500 μm thick CdWO4 scintillator for radioluminescence imaging. Despite its thinness, the unique scintillation properties of the Lu2O3:Eu scintillator allow us to capture single-positron decays with fourfold higher sensitivity, which is a significant achievement. The thin-film Lu2O3:Eu Scintillators also yield radioluminescence images where individual cells appear smaller and better resolved on average than with the CdWO4 Scintillators. Coupled with the thin-film scintillator technology, radioluminescence microscopy can yield valuable and clinically relevant data on the metabolism of single cells.
Qihua Zhao - One of the best experts on this subject based on the ideXlab platform.
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countering beam divergence effects with focused segmented Scintillators for high dqe megavoltage active matrix imagers
Physics in Medicine and Biology, 2012Co-Authors: Langechua Liu, Qihua Zhao, Larry E Antonuk, Youcef ElmohriAbstract:The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ∼1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through the utilization of thick, two-dimensional, segmented Scintillators with optically isolated crystals. However, this strategy is constrained by the degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented Scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented Scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented Scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ∼130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such Scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented Scintillators in MV AMFPIs.
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monte carlo investigations of the effect of beam divergence on thick segmented crystalline Scintillators for radiotherapy imaging
Physics in Medicine and Biology, 2010Co-Authors: Yi Wang, Youcef Elmohri, Larry E Antonuk, Qihua ZhaoAbstract:The use of thick, segmented Scintillators in electronic portal imagers offers the potential for significant improvement in x-ray detection efficiency compared to conventional phosphor screens. Such improvement substantially increases the detective quantum efficiency (DQE), leading to the possibility of achieving soft-tissue visualization at clinically practical (i.e. low) doses using megavoltage (MV) cone-beam computed tomography. While these DQE increases are greatest at zero spatial frequency, they are diminished at higher frequencies as a result of degradation of spatial resolution due to lateral spreading of secondary radiation within the scintillator—an effect that is more pronounced for thicker Scintillators. The extent of this spreading is even more accentuated for radiation impinging the scintillator at oblique angles of incidence due to beam divergence. In this paper, Monte Carlo simulations of radiation transport, performed to investigate and quantify the effects of beam divergence on the imaging performance of MV imagers based on two promising Scintillators (BGO and CsI:Tl), are reported. In these studies, 10–40 mm thick Scintillators, incorporating low-density polymer, or high-density tungsten septal walls, were examined for incident angles corresponding to that encountered at locations up to ~15 cm from the central beam axis (for an imager located 130 cm from a radiotherapy x-ray source). The simulations demonstrate progressively more severe spatial resolution degradation (quantified in terms of the effect on the modulation transfer function) as a function of increasing angle of incidence (as well as of the scintillator thickness). Since the noise power behavior was found to be largely independent of the incident angle, the dependence of the DQE on the incident angle is therefore primarily determined by the spatial resolution. The observed DQE degradation suggests that 10 mm thick Scintillators are not strongly affected by beam divergence for detector areas up to ~30 × 30 cm2. For thicker Scintillators, the area that is relatively unaffected is significantly reduced, requiring a focused scintillator geometry in order to preserve spatial resolution, and thus DQE.
Youcef Elmohri - One of the best experts on this subject based on the ideXlab platform.
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countering beam divergence effects with focused segmented Scintillators for high dqe megavoltage active matrix imagers
Physics in Medicine and Biology, 2012Co-Authors: Langechua Liu, Qihua Zhao, Larry E Antonuk, Youcef ElmohriAbstract:The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ∼1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through the utilization of thick, two-dimensional, segmented Scintillators with optically isolated crystals. However, this strategy is constrained by the degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented Scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented Scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented Scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ∼130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such Scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented Scintillators in MV AMFPIs.
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monte carlo investigations of the effect of beam divergence on thick segmented crystalline Scintillators for radiotherapy imaging
Physics in Medicine and Biology, 2010Co-Authors: Yi Wang, Youcef Elmohri, Larry E Antonuk, Qihua ZhaoAbstract:The use of thick, segmented Scintillators in electronic portal imagers offers the potential for significant improvement in x-ray detection efficiency compared to conventional phosphor screens. Such improvement substantially increases the detective quantum efficiency (DQE), leading to the possibility of achieving soft-tissue visualization at clinically practical (i.e. low) doses using megavoltage (MV) cone-beam computed tomography. While these DQE increases are greatest at zero spatial frequency, they are diminished at higher frequencies as a result of degradation of spatial resolution due to lateral spreading of secondary radiation within the scintillator—an effect that is more pronounced for thicker Scintillators. The extent of this spreading is even more accentuated for radiation impinging the scintillator at oblique angles of incidence due to beam divergence. In this paper, Monte Carlo simulations of radiation transport, performed to investigate and quantify the effects of beam divergence on the imaging performance of MV imagers based on two promising Scintillators (BGO and CsI:Tl), are reported. In these studies, 10–40 mm thick Scintillators, incorporating low-density polymer, or high-density tungsten septal walls, were examined for incident angles corresponding to that encountered at locations up to ~15 cm from the central beam axis (for an imager located 130 cm from a radiotherapy x-ray source). The simulations demonstrate progressively more severe spatial resolution degradation (quantified in terms of the effect on the modulation transfer function) as a function of increasing angle of incidence (as well as of the scintillator thickness). Since the noise power behavior was found to be largely independent of the incident angle, the dependence of the DQE on the incident angle is therefore primarily determined by the spatial resolution. The observed DQE degradation suggests that 10 mm thick Scintillators are not strongly affected by beam divergence for detector areas up to ~30 × 30 cm2. For thicker Scintillators, the area that is relatively unaffected is significantly reduced, requiring a focused scintillator geometry in order to preserve spatial resolution, and thus DQE.
Yutaka Fujimoto - One of the best experts on this subject based on the ideXlab platform.
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x ray detection properties of plastic Scintillators containing surface modified bi2o3 nanoparticles
Japanese Journal of Applied Physics, 2018Co-Authors: Fumiyuki Hiyama, Shunji Kishimoto, Rie Haruki, Yutaka Fujimoto, Fumihiko Nishikido, Masanori Koshimizu, Takio Noguchi, Tsutomu Aida, Seiichi Takami, Tadafumi AdschiriAbstract:Plastic Scintillators containing Bi2O3 nanoparticles (NPs) were developed as detectors for X-ray synchrotron radiation. A hydrothermal method was used to synthesize the NPs that had average particle sizes of less than 10 nm. Higher NP concentration led to a higher detection efficiency at 67.4 keV. The light yield of the scintillator containing 5 wt % Bi2O3 NPs was comparable with or higher than that of the commercially available plastic scintillator, EJ 256. The time resolution of the developed scintillation detector equipped with each sample scintillator was approximately 0.6 ns. Dispersion of nanoparticles within plastic Scintillators is generally applicable and has wide application as a method for preparation of plastic Scintillators for detecting X-ray synchrotron radiation.
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x ray detection properties of plastic Scintillators containing surface modified bi2o3nanoparticles
Japanese Journal of Applied Physics, 2018Co-Authors: Fumiyuki Hiyama, Shunji Kishimoto, Rie Haruki, Yutaka Fujimoto, Fumihiko Nishikido, Masanori Koshimizu, Takio Noguchi, Tsutomu Aida, Seiichi Takami, Tadafumi AdschiriAbstract:Plastic Scintillators containing Bi2O3 nanoparticles (NPs) were developed as detectors for X-ray synchrotron radiation. A hydrothermal method was used to synthesize the NPs that had average particle sizes of less than 10 nm. Higher NP concentration led to a higher detection efficiency at 67.4 keV. The light yield of the scintillator containing 5 wt % Bi2O3 NPs was comparable with or higher than that of the commercially available plastic scintillator, EJ 256. The time resolution of the developed scintillation detector equipped with each sample scintillator was approximately 0.6 ns. Dispersion of nanoparticles within plastic Scintillators is generally applicable and has wide application as a method for preparation of plastic Scintillators for detecting X-ray synchrotron radiation.
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X-ray detection capability of bismuth-loaded plastic Scintillators
Japanese Journal of Applied Physics, 2015Co-Authors: Masanori Koshimizu, Shunji Kishimoto, Rie Haruki, Matthieu Hamel, Guillaume Bertrand, Yutaka Fujimoto, Takayuki Yanagida, Fumihiko Nishikido, Keisuke AsaiAbstract:We evaluated the high-energy X-ray detection capabilities of Bi-loaded plastic Scintillators. The detection efficiency for 67.4 keV X-rays was successfully increased by increasing the Bi concentration. The detection efficiency of a plastic scintillator loaded with 10 wt % Bi was comparable to that of a commercially available plastic scintillator loaded with 5 wt % Pb, NE-142. A subnanosecond time resolution was achieved, and no long scintillation component appeared with Bi loading. These results indicate that Bi loading is an effective method of enhancing the detection efficiency for high-energy X-rays while preserving the timing properties of plastic Scintillators.
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comparative study of ceramic and single crystal ce gagg scintillator
Optical Materials, 2013Co-Authors: Takayuki Yanagida, Yutaka Fujimoto, Kei Kamada, Hideki Yagi, Takagimi YanagitaniAbstract:Abstract Recent study revealed that single crystal Ce:Gd 3 (Al,Ga) 5 O 12 (Ce:GAGG) showed good scintillation response under γ-ray exposure. We discover here that ceramic Ce:GAGG scintillator exhibited better performance than the single crystal counterpart. We developed Ce 1% doped ceramic and single crystal GAGG Scintillators with 1 mm thick and compared their properties. In radioluminescence spectra, they showed intense emission peaking at 530 nm due to Ce 3+ 5d–4f transition. The 137 Cs γ-ray induced light yields of ceramic and single crystal resulted 70 000 ph/MeV and 46 000 ph/MeV with primary decay times of 165 and 143 ns, respectively. At present, the observed light yield was the brightest in oxide Scintillators.
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temperature dependence of neutron gamma discrimination based on pulse shape discrimination technique in a rm ce licaalf _ 6 scintillator
IEEE Transactions on Nuclear Science, 2013Co-Authors: Kenichi Watanabe, Yoshiyuki Kondo, Atsushi Yamazaki, Akira Uritani, Tetsuo Iguchi, Noriaki Kawaguchi, Kentaro Fukuda, Sumito Ishidu, T Yanagida, Yutaka FujimotoAbstract:LiCaAlF6 Scintillators are one of the attractive Scintillators for neutron detection. To reduce the effect on gamma-rays, the Ce doped LiCaAlF6 Scintillators can discriminate the neutron and gamma-ray events based on the pulse shape discrimination technique. To apply the Scintillators for the oil logging, the high temperature characteristics must be investigated. In this paper, the temperature dependence of the neutron-gamma discrimination based on pulse shape discrimination technique in the Ce:LiCaAlF6 scintillator is investigated as one of the high temperature characteristics. The property of pulse shape discrimination in the Ce:LiCaAlF6 has small temperature dependence ranging from 25°C to 150°C. We concluded that the Ce:LiCaAlF6 Scintillators can discriminate neutron and gamma-ray events under high temperature condition up to 150°C .
Kapłon Łukasz - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and characterization of plastic Scintillators for the total-body J-PET scanner
2020Co-Authors: Kapłon ŁukaszAbstract:The aim of the research was to develop a polystyrene scintillator for use in the novel time-of-flight Jagiellonian Positron Emission Tomography (J-PET) scanner being elaborated for the whole-body imaging. To achieve this goal, polystyrene-based plastic Scintillators with the different chemical compositions were produced and characterized. Light output, decay time and emission spectra were measured to develop the best composition of the polystyrene scintillator
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Technical attenuation length measurement of plastic scintillator strips for the total-body J-PET scanner
'Institute of Electrical and Electronics Engineers (IEEE)', 2020Co-Authors: Kapłon ŁukaszAbstract:The aim of the performed technical attenuation length measurement is to compare light attenuation of a few commercially available plastic scintillator strips and to select the best scintillator type for the total-body Jagiellonian Positron Emission Tomograph (J-PET) construction. Few models of plastic Scintillators obtained from different manufacturers were tested. All strips had the same rectangular cross section and dimensions 6 mm × 24 mm × 1000 mm with all surfaces polished. The light attenuation length was measured by exciting the scintillator strip at different positions with an ultraviolet lamp emitting at 365 nm and reading light signal collected at one side of the strip by a silicon photodiode. Among measured plastic Scintillators, EJ-200 possesses the highest technical light attenuation length and is suitable for construction of total-body J-PET scanner
