Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507936
Joshua W. Kleppinger, S. Chaudhuri, Omerfaruk Karadavut, K. Mandal
High resolution Schottky barrier detectors (SBDs) were fabricated on 150 µm thick 4H-SiC epilayers using a proprietary device design. Electrical properties of the SBD junctions were characterized by temperature-dependent current-voltage (I-V- T) measurements which showed ultra-low leakage current densities lower than 100 pA cm−2at -150 V and remained below 1 µ A.cm−2 even at 600K. Electrically active deep levels present in the epilayers were identified and characterized by deep level transient spectroscopy (DLTS) which showed the presence of three deep levels - Ti(c), Z1/2 and EH6/7- with low concentrations (~1011 cm−3). The energy levels were investigated theoretically by density functional theory (DFT) calculations on intrinsic vacancies and titanium point defects. Pulse height spectra (PHS) were collected using a 241Am alpha source and a percentage energy resolution of 0.55% at 5486 keV was obtained. Further analysis of the forward bias I-V- T showed an improvement in ideality factor and barrier height at elevated temperature revealing the improvement of detection performance at higher temperature.
采用专有器件设计，在150µm厚的4H-SiC薄膜上制备了高分辨率肖特基势垒探测器(sdd)。通过温度相关的电流-电压(I-V- T)测量表征了SBD结的电学特性，结果表明，在-150 V时，泄漏电流密度低于100 pA cm - 2，即使在600K时也保持在1µa cm - 2以下。利用深能级瞬态光谱(deep level transient spectroscopy, dts)对脱膜中存在的电活性能级进行了鉴定和表征，发现存在3个低浓度(~1011 cm−3)的深能级Ti(c)、Z1/2和EH6/7。利用密度泛函理论(DFT)计算了本征空位和钛点缺陷的能级。采用241Am α源采集了脉冲高度光谱(PHS)，在5486 keV下获得了0.55%的百分比能量分辨率。进一步分析正向偏压I-V- T，发现理想因子和势垒高度在高温下有所提高，表明在高温下检测性能有所提高。
{"title":"First Principle Defect Analysis in 150 µm 4H-SiC Epitaxial Layer Schottky Barrier Detectors","authors":"Joshua W. Kleppinger, S. Chaudhuri, Omerfaruk Karadavut, K. Mandal","doi":"10.1109/NSS/MIC42677.2020.9507936","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507936","url":null,"abstract":"High resolution Schottky barrier detectors (SBDs) were fabricated on 150 µm thick 4H-SiC epilayers using a proprietary device design. Electrical properties of the SBD junctions were characterized by temperature-dependent current-voltage (I-V- T) measurements which showed ultra-low leakage current densities lower than 100 pA cm−2at -150 V and remained below 1 µ A.cm−2 even at 600K. Electrically active deep levels present in the epilayers were identified and characterized by deep level transient spectroscopy (DLTS) which showed the presence of three deep levels - Ti(c), Z1/2 and EH6/7- with low concentrations (~1011 cm−3). The energy levels were investigated theoretically by density functional theory (DFT) calculations on intrinsic vacancies and titanium point defects. Pulse height spectra (PHS) were collected using a 241Am alpha source and a percentage energy resolution of 0.55% at 5486 keV was obtained. Further analysis of the forward bias I-V- T showed an improvement in ideality factor and barrier height at elevated temperature revealing the improvement of detection performance at higher temperature.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"4 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73527197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507972
C. Agapopoulou, P. Dinaucourt, A. Dragone, D. Gong, C. de La Taille, N. Makovec, B. Markovic, G. Martin-Chassard, C. Milke, M. Morenas, L. Ruckman, S. Sacerdoti, A. Schwartzman, N. Seguin-Moreau, L. Serin, D. Su, J. Ye
1 Abstract—Designed and characterized by the HGTD collaboration, ALTIROC belongs to the family of readout ASICs used at the Large Hadron Collider (LHC) for the High Luminosity-LHC upgrade. ALTIROC1 is a 25-channel ASIC designed in CMOS 130 nm to read out the 5 x 5 matrix of 1.3 mm x 1.3 mm Low Gain Avalanche Diodes (LGAD) of the ATLAS HGTD detector. The targeted combined time resolution of the sensor and its readout electronics from 35 ps/hit (initial) to 70 ps/hit (end of operational lifetime). Each ASIC channel integrates an RF preamplifier followed by a high speed discriminator and two TDCs for Time-of-Arrival and Time-Over-Threshold measurements as well as a local memory. This front-end must exhibit an extremely low jitter noise while keeping a challenging power consumption of less than 4.5 mW per channel. This conference proceeding summarizes the ASIC's architecture, its measured performances compared to simulation, along with the requirements for the HEP experiments.
摘要:ALTIROC由HGTD合作设计和表征，属于大型强子对撞机(LHC)用于高亮度-LHC升级的读出asic家族。ALTIROC1是一款采用CMOS 130 nm设计的25通道ASIC，用于读取ATLAS HGTD探测器的1.3 mm x 1.3 mm低增益雪崩二极管(LGAD)的5 x 5矩阵。传感器及其读出电子器件的目标组合时间分辨率从35ps /命中(初始)到70ps /命中(运行寿命结束)。每个ASIC通道集成了一个RF前置放大器，随后是一个高速鉴别器和两个tdc，用于到达时间和超过阈值的测量，以及一个本地存储器。该前端必须具有极低的抖动噪声，同时保持每个通道低于4.5 mW的具有挑战性的功耗。本次会议总结了ASIC的架构，与仿真相比的测量性能，以及HEP实验的要求。
{"title":"ALTIROC 1, a 25 ps time resolution ASIC for the ATLAS High Granularity Timing Detector","authors":"C. Agapopoulou, P. Dinaucourt, A. Dragone, D. Gong, C. de La Taille, N. Makovec, B. Markovic, G. Martin-Chassard, C. Milke, M. Morenas, L. Ruckman, S. Sacerdoti, A. Schwartzman, N. Seguin-Moreau, L. Serin, D. Su, J. Ye","doi":"10.1109/NSS/MIC42677.2020.9507972","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507972","url":null,"abstract":"1 Abstract—Designed and characterized by the HGTD collaboration, ALTIROC belongs to the family of readout ASICs used at the Large Hadron Collider (LHC) for the High Luminosity-LHC upgrade. ALTIROC1 is a 25-channel ASIC designed in CMOS 130 nm to read out the 5 x 5 matrix of 1.3 mm x 1.3 mm Low Gain Avalanche Diodes (LGAD) of the ATLAS HGTD detector. The targeted combined time resolution of the sensor and its readout electronics from 35 ps/hit (initial) to 70 ps/hit (end of operational lifetime). Each ASIC channel integrates an RF preamplifier followed by a high speed discriminator and two TDCs for Time-of-Arrival and Time-Over-Threshold measurements as well as a local memory. This front-end must exhibit an extremely low jitter noise while keeping a challenging power consumption of less than 4.5 mW per channel. This conference proceeding summarizes the ASIC's architecture, its measured performances compared to simulation, along with the requirements for the HEP experiments.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"10 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74526313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507902
A. Proctor
Plastic scintillators made from Polyvinyl Toluene 1(PVT) doped with fluorescent dye are used extensively in homeland security, scrap metal inspections, and other applications that require a large-area, cost-effective gamma detector. Unfortunately, gamma ray detection with PVT results in only Compton-edge events which contribute to a broad continuum spectrum having no discernible features. Other methods of obtaining information from low resolution PVT spectra have been described in publications but at the present time there is no practical method suitable for routine use. We have developed a method based on Particle Swarm Optimization (PSO) which analyzes raw PVT spectra and provides a histogram of contribution(s) vs. incident monoenergetic gamma energy(s). This is accomplished by summing multiple single-energy calculated PVT gamma responses into a ‘spectrum’ until a ‘best fit’ to the original raw data spectrum is obtained. The input set of response functions are calculated using MCNP5 and cover an appropriate energy range; we use a set of 255 response functions with 11 keV spacing between them (this corresponds to the ADC gain used in our PVT detectors). This set provides a range of 11 keV to 2805 keV for incident monoenergetic gamma energies which is suitable for most applications. Usually, we find that only one or two gamma response functions contribute to a ‘peak’ in the calculated histogram. Traditional radionuclide identification methods can be applied once the contribution gamma energies have been identified. As an added benefit: locating natural background gamma rays: 238 keV, 609 keV, 1460 keV, and 2614 keV in the deconvolved spectrum can be used to gain-stabilize the PVT detector.
{"title":"Deconvolving Plastic Scintillator Gamma-Ray Spectra Using Particle Swarm Optimization","authors":"A. Proctor","doi":"10.1109/NSS/MIC42677.2020.9507902","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507902","url":null,"abstract":"Plastic scintillators made from Polyvinyl Toluene 1(PVT) doped with fluorescent dye are used extensively in homeland security, scrap metal inspections, and other applications that require a large-area, cost-effective gamma detector. Unfortunately, gamma ray detection with PVT results in only Compton-edge events which contribute to a broad continuum spectrum having no discernible features. Other methods of obtaining information from low resolution PVT spectra have been described in publications but at the present time there is no practical method suitable for routine use. We have developed a method based on Particle Swarm Optimization (PSO) which analyzes raw PVT spectra and provides a histogram of contribution(s) vs. incident monoenergetic gamma energy(s). This is accomplished by summing multiple single-energy calculated PVT gamma responses into a ‘spectrum’ until a ‘best fit’ to the original raw data spectrum is obtained. The input set of response functions are calculated using MCNP5 and cover an appropriate energy range; we use a set of 255 response functions with 11 keV spacing between them (this corresponds to the ADC gain used in our PVT detectors). This set provides a range of 11 keV to 2805 keV for incident monoenergetic gamma energies which is suitable for most applications. Usually, we find that only one or two gamma response functions contribute to a ‘peak’ in the calculated histogram. Traditional radionuclide identification methods can be applied once the contribution gamma energies have been identified. As an added benefit: locating natural background gamma rays: 238 keV, 609 keV, 1460 keV, and 2614 keV in the deconvolved spectrum can be used to gain-stabilize the PVT detector.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"80 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74591751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9508034
A. Castoldi, C. Guazzoni, S. Aschauer, L. Strüder, K. Hansen, S. Maffessanti, M. Porro
The implementation of a Depleted Field Effect Transistor (DEPFET) in each pixel of the DSSC (DEPFET Sensor with Signal Compression) X-ray camera for the European XFEL is intended to provide the appropriate signal compression at high injection levels and low noise figure. The aim of this work is the assessment of the non-linear DEPFET response. To this purpose the response of DSSC DEPFET pixels has been measured and analyzed up to 2 MeV equivalent deposited energy in the experimental conditions foreseen for the final DSSC camera. An appropriate fitting function has been introduced to predict the compression “kink” positions and to model the shape of the compression curve. The preliminary results of this study will be summarized.
{"title":"Assessment of the Non-Linear Response of DEPFET Sensors with Signal Compression","authors":"A. Castoldi, C. Guazzoni, S. Aschauer, L. Strüder, K. Hansen, S. Maffessanti, M. Porro","doi":"10.1109/NSS/MIC42677.2020.9508034","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9508034","url":null,"abstract":"The implementation of a Depleted Field Effect Transistor (DEPFET) in each pixel of the DSSC (DEPFET Sensor with Signal Compression) X-ray camera for the European XFEL is intended to provide the appropriate signal compression at high injection levels and low noise figure. The aim of this work is the assessment of the non-linear DEPFET response. To this purpose the response of DSSC DEPFET pixels has been measured and analyzed up to 2 MeV equivalent deposited energy in the experimental conditions foreseen for the final DSSC camera. An appropriate fitting function has been introduced to predict the compression “kink” positions and to model the shape of the compression curve. The preliminary results of this study will be summarized.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"32 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75363054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507768
Alex Grievson, C. J. Taylor, N. Roberts, M. Bunce, M. Joyce
Experimental measurements to explore the effect of detector voltage, pulse-shape discrimination (PSD) threshold and detector shielding on time-of-flight measurements of the 252Cf neutron spectrum made with organic scintillation detectors are described. It is found that detector voltage has a major effect, whilst changing the PSD threshold and shielding the detectors to optimize sensitivity to the desired γ-neutron correlation results in a small effect.
{"title":"Time-of-Flight Spectroscopy of 252Cf Spontaneous Fission Neutrons: Influences of Detector Voltage, Pulse-Shape Discrimination and Shielding","authors":"Alex Grievson, C. J. Taylor, N. Roberts, M. Bunce, M. Joyce","doi":"10.1109/NSS/MIC42677.2020.9507768","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507768","url":null,"abstract":"Experimental measurements to explore the effect of detector voltage, pulse-shape discrimination (PSD) threshold and detector shielding on time-of-flight measurements of the 252Cf neutron spectrum made with organic scintillation detectors are described. It is found that detector voltage has a major effect, whilst changing the PSD threshold and shielding the detectors to optimize sensitivity to the desired γ-neutron correlation results in a small effect.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"23 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74217623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507821
C. Wu, M. S. Lee, C. Levin
We demonstrate a simulation-based proof-of-concept for superior inter-crystal scatter (ICS) event positioning using a feed-forward neural network (NN) architecture compared to traditional winner-takes-all (WTA) and loser-takes-all (LTA) algorithms. Using a GATE Monte Carlo simulation of a 3D position-sensitive scintillation detector module comprising long crystals read out from the side using SiPMs with 3×3×3 mm3 effective detector voxels, we observe NN ICS event positioning accuracies of 0.753 to 0.680 when the number of interactions per annihilation photon ranges from 2 to 5: significantly more robust compared to 0.726 to 0.367 for LTA and 0.613 to 0.251 for WTA methods over the same range. We then scale the single-detector simulation into a 25 cm diameter PET brain imaging system and reconstruct contrast and resolution phantoms for image quality analysis. The NN model outperformed both WTA and LTA, with image normalized Mean Absolute Errors of 0.030 and 0.122 for contrast and resolution phantoms compared to 0.046, 0.178 and 0.034, 0.140 for WTA and LTA. The NN demonstrated 6.04 to 8.95% higher Contrast Recovery (from resolution phantom), 0.53 to 2.85% larger Contrast Noise Ratio (from contrast phantom), and 2.13 to 6.34% higher Modulation Transfer Function values (from resolution phantom) compared to LTA, which performed second-best. The upper bound for these NN relative improvements occurred with features near the spatial resolution limit of the simulated system (2 mm). Our results indicate the NN positioning approach we examined improves most image quality and quantitation figures of merit.
{"title":"Neural Network-based Inter-crystal Scatter Event Positioning in a PET System Design Based on 3D Position Sensitive Detectors","authors":"C. Wu, M. S. Lee, C. Levin","doi":"10.1109/NSS/MIC42677.2020.9507821","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507821","url":null,"abstract":"We demonstrate a simulation-based proof-of-concept for superior inter-crystal scatter (ICS) event positioning using a feed-forward neural network (NN) architecture compared to traditional winner-takes-all (WTA) and loser-takes-all (LTA) algorithms. Using a GATE Monte Carlo simulation of a 3D position-sensitive scintillation detector module comprising long crystals read out from the side using SiPMs with 3×3×3 mm3 effective detector voxels, we observe NN ICS event positioning accuracies of 0.753 to 0.680 when the number of interactions per annihilation photon ranges from 2 to 5: significantly more robust compared to 0.726 to 0.367 for LTA and 0.613 to 0.251 for WTA methods over the same range. We then scale the single-detector simulation into a 25 cm diameter PET brain imaging system and reconstruct contrast and resolution phantoms for image quality analysis. The NN model outperformed both WTA and LTA, with image normalized Mean Absolute Errors of 0.030 and 0.122 for contrast and resolution phantoms compared to 0.046, 0.178 and 0.034, 0.140 for WTA and LTA. The NN demonstrated 6.04 to 8.95% higher Contrast Recovery (from resolution phantom), 0.53 to 2.85% larger Contrast Noise Ratio (from contrast phantom), and 2.13 to 6.34% higher Modulation Transfer Function values (from resolution phantom) compared to LTA, which performed second-best. The upper bound for these NN relative improvements occurred with features near the spatial resolution limit of the simulated system (2 mm). Our results indicate the NN positioning approach we examined improves most image quality and quantitation figures of merit.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"33 4","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72584041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507843
T. Aso, C. Omachi, T. Toshito, T. Sasaki
The particle therapy system simulation framework (PTSIM) is a Geant4 based Monte Carlo simulation software developed for radiation therapy. It has been continuously extending the functions to facilitate advanced researches in medical physics domain. Consequently, the PTSIM is used in many facilities for verification of treatment plans and quality assurances. In the PTSIM, various types of beam devices are provided as software components named “beam-modules”. The geometry is constructed using a class of the beam-module and the detail geometric parameters in the ASCII data format. This strategy contributed that allows the PTSIM users to easily find the beam-module from the categorized types of beam devices and to develop a rapid prototyping of treatment port in the simulation. However, radiation therapy facilities may introduce variants of existing beam-modules, that may require the implementation of a new class for the beam-module in the PTSIM. In order to respond to such requirements without any coding effort, the interface for the Geometry Description Markup Language (GDML) has been introduced in the PTSIM. The GDML is a specialized XML-based language for an application-independent persistent format. Therefore, it can describe a user-defined complex geometry and exchanging the geometry data file among different facilities. In addition, for the purpose of examining complex geometries, a new interface for the ParaView visualization software has been developed. The interface converts the geometry in the PTSIM to the structured points data in the VTK legacy format. This paper reports on the implementations and the usages of GDML and ParaView interfaces in the PTSIM.
{"title":"Interface for Exchanging Geometric Parameters in Geant4 Based Particle Therapy Simulation Framework","authors":"T. Aso, C. Omachi, T. Toshito, T. Sasaki","doi":"10.1109/NSS/MIC42677.2020.9507843","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507843","url":null,"abstract":"The particle therapy system simulation framework (PTSIM) is a Geant4 based Monte Carlo simulation software developed for radiation therapy. It has been continuously extending the functions to facilitate advanced researches in medical physics domain. Consequently, the PTSIM is used in many facilities for verification of treatment plans and quality assurances. In the PTSIM, various types of beam devices are provided as software components named “beam-modules”. The geometry is constructed using a class of the beam-module and the detail geometric parameters in the ASCII data format. This strategy contributed that allows the PTSIM users to easily find the beam-module from the categorized types of beam devices and to develop a rapid prototyping of treatment port in the simulation. However, radiation therapy facilities may introduce variants of existing beam-modules, that may require the implementation of a new class for the beam-module in the PTSIM. In order to respond to such requirements without any coding effort, the interface for the Geometry Description Markup Language (GDML) has been introduced in the PTSIM. The GDML is a specialized XML-based language for an application-independent persistent format. Therefore, it can describe a user-defined complex geometry and exchanging the geometry data file among different facilities. In addition, for the purpose of examining complex geometries, a new interface for the ParaView visualization software has been developed. The interface converts the geometry in the PTSIM to the structured points data in the VTK legacy format. This paper reports on the implementations and the usages of GDML and ParaView interfaces in the PTSIM.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"80 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78219114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507823
O. Maslyanchuk, V. Strebezhev, P. Fochuk, I. Fodchuk, M. Solovan, M. Sorokatyi, I. Boledzyuk, R. James
In this paper, the transformations of the morphology and surface structure of CdTe crystals under the action of pulsed laser radiation and the properties of laser-optimized Schottky diode X/γ-ray detectors developed by Ni and NiO deposition onto commercially available (111) oriented CdTe:Cl wafers has been investigated. Using scanning electron and atomic force microscopy, it was shown that, depending on the energy density and laser pulse duration, the morphology, phase composition and distribution of the system of defects and inclusions in the surface areas of CdTe crystals can be optimized. The analysis of the effect of laser treatment on the electrical and spectrometric properties CdTe X/γ-ray detectors under study was also carried out.
{"title":"The Influence of Laser Surface Treatment on Properties of CdTe X- and γ-ray Detectors","authors":"O. Maslyanchuk, V. Strebezhev, P. Fochuk, I. Fodchuk, M. Solovan, M. Sorokatyi, I. Boledzyuk, R. James","doi":"10.1109/NSS/MIC42677.2020.9507823","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507823","url":null,"abstract":"In this paper, the transformations of the morphology and surface structure of CdTe crystals under the action of pulsed laser radiation and the properties of laser-optimized Schottky diode X/γ-ray detectors developed by Ni and NiO deposition onto commercially available (111) oriented CdTe:Cl wafers has been investigated. Using scanning electron and atomic force microscopy, it was shown that, depending on the energy density and laser pulse duration, the morphology, phase composition and distribution of the system of defects and inclusions in the surface areas of CdTe crystals can be optimized. The analysis of the effect of laser treatment on the electrical and spectrometric properties CdTe X/γ-ray detectors under study was also carried out.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"13 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78223952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9507772
Hossein ARABI, H. Zaidi
Non-local mean (NLM) denoising is commonly used for noise suppression in natural as well as medical imaging. Basically, the NLM filter takes advantage of the redundant information present in the image in the form of repeated structures/patterns to identify the underlying signals. In medical imaging (particularly PET and SPECT imaging), different representations of the image data under study (target or original image) could be reconstructed via applying different reconstruction settings. These representative (auxiliary) images bear very similar patterns/structures to the original/target image with different signal-to-noise ratios (SNR) which are ideal for use in the NLM denoising approach. This study proposed the multiple-reconstruction NLM filtering approach (referred to as MR-NLM) for noise reduction in PET imaging, wherein the redundant information present in auxiliary PET images are employed to conduct the NLM denoising process. The MR-NLM method relies on 12 additional PET image reconstructions (apart from the target PET image) using the same iterative algorithm with different iterations and subset numbers. Thereafter, for each target voxel, patches of voxels are extracted at the same location from all auxiliary PET images to be fed into the NLM smoothing process. To evaluate the performance of the MR-NLM algorithm, post-reconstruction denoising approaches including the conventional NLM, bilateral, and Gaussian filters were implemented and compared using 25 18F-FDG clinical whole-body (WB) PET/CT studies. The clinical studies demonstrated superior performance of the MR-NLM approach which established a promising compromise between noise suppression and preservation of the underlying signal/structures in PET images leading to higher SNR compared to the conventional NLM approach (34.9±5.7 versus 32.4±5.5). Though MR-NLM exhibited promising performance, this method suffers from long processing time due to the requirement of multiple reconstructions of raw PET data.
{"title":"Multiple PET Reconstruction Assisted Non-local Mean Denoising of PET Images","authors":"Hossein ARABI, H. Zaidi","doi":"10.1109/NSS/MIC42677.2020.9507772","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9507772","url":null,"abstract":"Non-local mean (NLM) denoising is commonly used for noise suppression in natural as well as medical imaging. Basically, the NLM filter takes advantage of the redundant information present in the image in the form of repeated structures/patterns to identify the underlying signals. In medical imaging (particularly PET and SPECT imaging), different representations of the image data under study (target or original image) could be reconstructed via applying different reconstruction settings. These representative (auxiliary) images bear very similar patterns/structures to the original/target image with different signal-to-noise ratios (SNR) which are ideal for use in the NLM denoising approach. This study proposed the multiple-reconstruction NLM filtering approach (referred to as MR-NLM) for noise reduction in PET imaging, wherein the redundant information present in auxiliary PET images are employed to conduct the NLM denoising process. The MR-NLM method relies on 12 additional PET image reconstructions (apart from the target PET image) using the same iterative algorithm with different iterations and subset numbers. Thereafter, for each target voxel, patches of voxels are extracted at the same location from all auxiliary PET images to be fed into the NLM smoothing process. To evaluate the performance of the MR-NLM algorithm, post-reconstruction denoising approaches including the conventional NLM, bilateral, and Gaussian filters were implemented and compared using 25 18F-FDG clinical whole-body (WB) PET/CT studies. The clinical studies demonstrated superior performance of the MR-NLM approach which established a promising compromise between noise suppression and preservation of the underlying signal/structures in PET images leading to higher SNR compared to the conventional NLM approach (34.9±5.7 versus 32.4±5.5). Though MR-NLM exhibited promising performance, this method suffers from long processing time due to the requirement of multiple reconstructions of raw PET data.","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"19 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80167233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-31DOI: 10.1109/NSS/MIC42677.2020.9508016
S. Pourashraf, A. Gonzalez-Montoro, M. S. Lee, J. Cates, Jun Yeon Won, Zhixiang Zhao, Jae Sung Lee, C. Levin
To achieve < 100 ps Coincidence Time Resolution (CTR) and a > 2 - fold improvement in reconstructed image Signal to Noise Ratio (SNR) compared to state-of-the-art TOF-PET scanners, we have evaluated CTR performance of three different mixed-signal front-end electronic configurations. The proposed TOF-PET detector elements are based on two 3×3×10 mm3 “LGSO” crystal segments for a 20 mm effective length and side-coupled to arrays of 3×3 mm2 SiPMs. The front-end readouts were based on: a) high speed RF amplifiers; b) NINO ASIC as discriminator, and; c) combination of both RF+NINO. Coincidence data were experimentally acquired using the 10 mm length crystals, a low jitter FPGA-based TDC, several SiPM bias voltages, and NINO thresholds, achieving CTR value of 103.3 ± 1.5 ps FWHM using configuration (c). This value is much improved compared to the results achieved using configurations (a) and (b).
{"title":"Investigation of Analog and Digital Signal Processing Chains for a Prototype TOF-PET System with 100 ps Coincidence Time Resolution","authors":"S. Pourashraf, A. Gonzalez-Montoro, M. S. Lee, J. Cates, Jun Yeon Won, Zhixiang Zhao, Jae Sung Lee, C. Levin","doi":"10.1109/NSS/MIC42677.2020.9508016","DOIUrl":"https://doi.org/10.1109/NSS/MIC42677.2020.9508016","url":null,"abstract":"To achieve < 100 ps Coincidence Time Resolution (CTR) and a > 2 - fold improvement in reconstructed image Signal to Noise Ratio (SNR) compared to state-of-the-art TOF-PET scanners, we have evaluated CTR performance of three different mixed-signal front-end electronic configurations. The proposed TOF-PET detector elements are based on two 3×3×10 mm3 “LGSO” crystal segments for a 20 mm effective length and side-coupled to arrays of 3×3 mm2 SiPMs. The front-end readouts were based on: a) high speed RF amplifiers; b) NINO ASIC as discriminator, and; c) combination of both RF+NINO. Coincidence data were experimentally acquired using the 10 mm length crystals, a low jitter FPGA-based TDC, several SiPM bias voltages, and NINO thresholds, achieving CTR value of 103.3 ± 1.5 ps FWHM using configuration (c). This value is much improved compared to the results achieved using configurations (a) and (b).","PeriodicalId":6760,"journal":{"name":"2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)","volume":"35 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81905485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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