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Pre-Treatment Dose Verification of Imrt Using Gafchromic Ebt3 Film and 2DArray
摘要： Purpose: The present work deals with pre-treatment dosimetric verification of 10 prostate intensity-modulated radiotherapy (IMRT) plans obtained by Gafchromic EBT3 film and 2D-Array seven29 to establish quality control protocol for the delivery of prostate IMRT in our clinic. Methods: 10 prostate patients were irradiated according to IMRT techniques with 6 MV photon beams produced by a Varian DHX linear accelerator. Dose plans were computed using Eclipse 8.9 (version8.9, Varian, Palo Alto, CA, United States) treatment planning system (TPS). Pre-treatment dosimetric verification was carried out on field-per-field and total IMRT plan basis measuring 2D dose distributions in RW3 solid water phantom (PTW-Freiburg, Germany). For 10 patient plans, the dose distribution was re-calculated with the phantom CT scan and delivered to the phantom with the original and 0 degrees gantry, collimator and table angles. Thus IMRT quality control (QC) plans were generated. Dose distribution measurements were measured with Gafchromic EBT3 film and 2D-Array seven29 (PTW-Freiburg, Germany) two dimensional ionization chamber system. Verification measurements of total IMRT plans and each individual beams were compared with expected dose maps, and differences were evaluated by Verisoft program (PTW-Freiburg, Germany). To provide comparisons of multidimensional dose distributions, dose comparison tools such as gamma dose distribution, distance- to- agreement (DTA) and dose difference (DD) have been developed. The gamma dose distribution tool was used in our study. Three different gamma criteria of dose difference (DD) and distance to agreement (DTA) (3%/3 mm, 4%/4 mm and 5%/5 mm DD / DTA) are selected. These criteria are evaluated while suppressing the dose of 5% from dose distribution. Criterion validity accepted as section with gamma value less than or equal to 1 (γ ≤ 1) to be 90%. Results: In the comparison of dose distributions obtained from TPS and the results of PTW 2D-Array seven29 and Gafchromic EBT3 film dosimetry systems, it was showed that the compatibility of both methods were above 90% with respect to 3% DD and 3mm DTA criteria. PTW 2D-Array seven29 results compared to the results of the film was closer to the TPS data and this difference was statistically meaningful (p<0.05). If the range of criteria is increased, the compatibility increases and it reaches to 100%. It was observed that analyzing by measuring all fields which are composing IMRT plans and analyzing by measuring each individual fields at the same time, made no statistically meaningful difference (p>0.05). Conclusions: The measurements performed with PTW 2D-Array seven29 were closer to the TPS data than film measurements and it takes less time during clinical use, so it could be preferred for routine use. The present results suggest the gamma criteria of 3%/3 mm as the most suitable criteria for prostate IMRT quality assurance.
关键词： Gamma analysis,Gafchromic EBT3 film,2D-Array seven29,RW3 solid water phantom,IMRT
更新于2025-09-19 17:15:36
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Influence of Gamma-ray irradiation on the fluorescence lifetime of Bi/Er co-doped fibers
摘要： We report the radiation effect on fluorescence lifetime (FLT) of the bismuth and erbium co-doped fiber. For emission peak at 1138 nm, the FLT is increased at 0-0.3 kGy, and then is decreased at 0.3-3 kGy. However, for emission peak at 1534 nm of Er3+, its FLT is decreased all the way.
关键词： gamma irradiation,FLT,BEDF,absorption spectrum
更新于2025-09-19 17:15:36
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[IEEE 2018 4th International Conference on Devices, Circuits and Systems (ICDCS) - Coimbatore, India (2018.3.16-2018.3.17)] 2018 4th International Conference on Devices, Circuits and Systems (ICDCS) - Comparative Study of CMOS based Dosimeters for Gamma Radiation
摘要： In this paper, a quantitative comparison study of the CMOS based Double Gate RADFET, Gate All Around (GAA) RADFET, Junctionless Double Gate (JL-DG) RADFET dosimeter and their electrical performance has been carried out. Gamma radiation Model of Sentaurus 3D Device simulator has been used to investigate the trapping detrapping of electron hole due to the moderate dose radiation environment. The impact of the total dose on the threshold voltage and drain current has been addressed. The obtained results indicate improvement in the subthreshold parameters of JL DG RADFET as compared to the conventional DG RADFET and GAA RADFET dosimeter.
关键词： Threshold Voltage,Sentaurus TCAD,JL DG RADFET,DG RADFET,Gamma Radiation Model,GAA MOSFET
更新于2025-09-19 17:15:36
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Annihilation gamma imaging for carbon ion beam range monitoring using Si/CdTe Compton camera
摘要： In this study, we performed on-beam monitoring of 511-keV annihilation gamma emissions using a Compton camera. Beam monitoring experiments were conducted using carbon ion beams of 290 MeV/u irradiated on a polymethyl methacrylate (PMMA) phantom. The intensity of the beams was 3×10^9 particles per pulse, with 20 pulses per minute. A Compton camera based on a silicon/cadmium telluride (Si/CdTe) detector was used to monitor the annihilation gamma rays emitted from the phantom. We successfully reconstructed the energy events of 511-keV annihilation gamma rays and developed Compton images using a simple back-projection method. The distribution of the annihilation gamma ray generation traced the beam trajectory and the peak intensity position was a few millimeters shorter than the Bragg peak position. Moreover, the effect of the beam range shifter with 30-, 60-, and 90-mm water equivalent thickness was clearly visualized in the reconstructed Compton images. The experimentally measured values of the corresponding range shifts in the PMMA phantom (28.70 mm, 52.49 mm, and 76.77 mm, respectively) were consistent with the shifts of the Bragg peak position (25.50 mm, 51.30 mm and 76.70 mm, respectively) evaluated by Monte Carlo simulation. The results show that the Si/CdTe Compton camera has strong potential for on-beam monitoring of annihilation gamma rays in particle therapy in clinical situations.
关键词： Compton camera,Beam monitoring,Annihilation gamma imaging,Carbon ion radiotherapy
更新于2025-09-19 17:15:36
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Development of a high resolution LaGPS imaging detector with pulse shape discrimination capability of different types of radiations
摘要： Ce doped (Gd,La)2Si2O7 (LaGPS) is a new scintillator which has high light output and is a promising candidate for high resolution radiation imaging detectors. Thus we developed a radiation imaging detector using a LaGPS plate combined with a position sensitive photomultiplier tube (PSPMT) and evaluated the performance. We found that the decay times of LaGPS were different with the types of radiations and the separations of the images of the different types of radiations were possible using pulse shape discrimination. The spatial resolution for Am-241 alpha particles (5.5 MeV) was better than 0.31 mm FWHM and the energy resolution was 11 % FWHM. The spatial resolution for Sr–Y-90 beta particles was ～0.6 mm FWHM and those for Co-57 gamma photons (122 keV) and Cs-137 X-ray (～35 keV) were better than 0.6 mm FWHM and ～0.8 mm FWHM, respectively. The decay times for alpha particles, beta particles, and gamma photons were 143 ns, 124 ns, and 119 ns, respectively. With these different decay times, the separation of alpha particles and gamma photons or beta particles was possible using the pulse shape discrimination. We conclude that the developed LaGPS imaging detector has high resolution for all types of radiations and is also capable of the simultaneous imaging and separating the different types of radiations.
关键词： Alpha particles,Imaging,Pulse shape discrimination,Beta particles,Gamma photons,Decay time,LaGPS
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Sandwich in the Middle: Enhancing the Optomechanical Coupling
摘要： This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators (Eu), GYGAG(Ce) and CsI(Na).
关键词： Gamma ray detectors,luminescence,solid scintillation detectors
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 5th International Conference on Wireless and Telematics (ICWT) - Yogyakarta, Indonesia (2019.7.25-2019.7.26)] 2019 IEEE 5th International Conference on Wireless and Telematics (ICWT) - The Behavioral Study of an Optical Injection-Locked Semiconductor Laser under the Influence of Intensity and Phase Noise
摘要： Channel electron multiplier (CEM) and microchannel plate (MCP) detectors are routinely used in space instrumentation for measurement of space plasmas. Our goal is to understand the relative sensitivities of these detectors to penetrating radiation in space, which can generate background counts and shorten detector lifetime. We use keV -rays as a proxy for penetrating radiation such as -rays, cosmic rays, and high-energy electrons and protons that are ubiquitous in the space environment. We find that MCP detectors are times more sensitive to keV -rays than CEM detectors. This is attributed to the larger total area of multiplication channels in an MCP detector that is sensitive to electronic excitation and ionization resulting from the interaction of penetrating radiation with the detector material. In contrast to the CEM detector, whose quantum efficiency keV -rays is found to be 0.00175 and largely independent of detector bias, the quantum efficiency of the MCP detector is strongly dependent on the detector bias, with a power law index of 5.5. Background counts in MCP detectors from penetrating radiation can be reduced using MCP geometries with higher pitch and smaller channel diameter.
关键词： gamma-ray effects,radiation effects,plasma measurements,Electron multipliers
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of Uncertainty Measurement of Radionuclides Minimum Detectable Activity in Large Plastic Scinllators
摘要： This work is devoted to the evaluation of the measurement uncertainty of minimum detectable activity (MDA) for 137Cs on its gamma radiation with large plastic scintillators (PS) used in the portal monitors (PM). The influence of scintillators volume and irradiation geometry on the MDA evaluation of the measurement uncertainty was studied. It is shown that the estimated expanded MDA measurement uncertainty interval on 137Cs is 21—23 per cent. The absolute value of the MDA measurement uncertainty when changing geometry of irradiation increases 10 times. Change in the volumes of the examined PS causes a change of MDA measurement uncertainty within 10 per cent.
关键词： gamma radiation,MDA,portal monitor,PS scintillator,detector,uncertainty of MDA
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - The Optimal Geometry of the Acousto-Optic Interaction in Selected Crystalline Materials Determined by Extreme Surfaces Method
摘要： Segmented gamma scanning (SGS) and tomographic gamma scanning (TGS) are two traditional detection techniques for low and intermediate level radioactive waste drum. This paper proposes one detection method named semi-tomographic gamma scanning (STGS) to avoid the poor detection accuracy of SGS and shorten detection time of TGS. This method and its algorithm synthesize the principles of SGS and TGS. In this method, each segment is divided into annual voxels and tomography is used in the radiation reconstruction. The accuracy of STGS is veri?ed by experiments and simulations simultaneously for the 208 liter standard waste drums which contains three types of nuclides. The cases of point source or multi-point sources, uniform or nonuniform materials are employed for comparison. The results show that STGS exhibits a large improvement in the detection performance, and the reconstruction error and statistical bias are reduced by one quarter to one third or less for most cases if compared with SGS.
关键词： Non-destructive assay,semi-tomographic gamma scanning (STGS),radioactive waste
更新于2025-09-19 17:13:59
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Optimization of Processing Parameters of Laser Skin Welding in vitro Combining the Response Surface Methodology with NSGA- II
摘要： The broadband afterglow of GW170817/GRB 170817A is believed to be from an off-axis structured jet. The central engine of a gamma-ray burst usually launches a pair of outflows that move oppositely. It is reasonable to consider the emission from double-sided structured jets, with a near-jet moving toward us and a counter-jet moving away from us. Assuming that the two branches of the jet have the same physical parameters, we have calculated their radio emission. It is found that the counter-jet component will emerge in the radio light curves ～2500 days post-merger. It typically leads to a plateau in the light curve, thus it could be revealed by high accuracy radio observations. We have also considered the possibilities that both branches have different parameters, and found that if some of the physical parameters of the counter-jet are evaluated more favorably than those of the near-jet, then the counter-jet emission will be enhanced and will clearly show up as an obvious plateau or even a rebrightening. For example, when the circumburst medium encountered by the counter-jet is assumed to be 100 times denser than that of the near-jet, a remarkable radio plateau will appear at ～600 days. However, in X-ray bands, the counter-jet component is generally too faint to be discerned. It is argued that the late radio observations of GW170817/GRB 170817A can help determine the key parameters and diagnose the environment of the event.
关键词： gamma-ray burst: individual (GRB 170817A),ISM: jets and outflows,methods: numerical
更新于2025-09-19 17:13:59