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Application of TG-100 risk analysis methods to the acceptance testing and commissioning process of a Halcyon linear accelerator
摘要： Purpose: A new type of linear accelerator (linac) was recently introduced into the market by a major manufacturer. Our institution is one of the early users of this pre-assembled and pre-configured dual-layer MLC, ring-gantry linac – HalcyonTM (1st version). We performed a set of full acceptance testing and commissioning (ATC) measurements for three Halcyon machines and compared the measured data with the standard beam model provided by the manufacturer. The ATC measurements were performed following the guidelines given in different AAPM protocols as well as guidelines provided by the manufacturer. The purpose of the present work was to perform a risk assessment of the ATC process for this new type of linac and investigate whether the results obtained from this analysis could potentially be used as a guideline for improving the design features of this type of linac. Methods: AAPM’s TG100 risk assessment methodology was applied to the ATC process. The acceptance testing process relied heavily on the use of a manufacturer-supplied phantom and the automated analysis of EPID images. For the commissioning process, a conventional measurement setup and process (e.g. use of water tank for scanning) was largely used. ATC was performed using guidelines recommended in various AAPM protocols (e.g. TG-106, TG-51) as well as guidelines provided by the manufacturer. Six medical physicists were involved in this study. Process maps, process steps and failure modes (FMs) were generated for the ATC procedures. Failure Modes and Effects Analysis (FMEA) were performed following the guidelines given in AAPM TG-100 protocol. The top 5 and top 10 highest-ranked FMs were identified for the acceptance and commissioning procedures respectively. Quality control measures were suggested to mitigate these FMs. Results: A total of 38 steps and 88 FMs were identified for the entire ATC process. 14 steps and 34 FMs arose from acceptance testing. The top 5 FMs that were identified could potentially be mitigated by the manufacturer. For commissioning, a total of 24 steps and 54 potential FMs were identified. The use of separate measurement tools that are not machine-integrated has been identified as a cause for the higher number of steps and FMs generated from the conventional ATC approach. More than half of the quality control measures recommended for both acceptance and commissioning could potentially be incorporated by the manufacturer in the design of the Halcyon machine. Conclusion: This paper presents the results of Failure Modes and Effects Analysis and quality control measures to mitigate the failure modes for the acceptance testing and commissioning process for Halcyon machine. Unique FMs that result from the differences in the ATC guidelines provided by the vendor and current conventional protocols, and the challenges of performing the ATC due to the new linac features and ring-gantry design were highlighted for the first time. The FMs identified in the present work along with the suggested quality control measures, could potentially be used to improve the design features of future ring-gantry type of linacs that are likely to be pre-assembled, pre-configured, and heavily reliant on automation and image-guidance.
关键词： new ring-gantry linac,reference dosimetry,TG100,TG-51,Failure Modes and Effects Analysis (FMEA),Acceptance testing and Commissioning
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Characterization of Multilayered Ceramic Capacitors via Piezoelectric Force Microscopy
摘要： The coupling between an electrical and mechanical response in a material is a fundamental property that provides functionality to a variety of applications ranging from sensors and actuators to energy harvesting and biology. Most materials exhibit electromechanical coupling in nanometer-sized domains. Therefore, to understand the relationship between structure and function of these materials, characterization on the nanoscale is required. This property can be directly measured in a non-destructive manner using piezoelectric force microscopy (PFM), a mode that comes standard in all atomic force microscopes (AFMs) from Park Systems. Additionally, PFM can be used as a spectroscopic tool to evaluate switching of piezoelectric domains. Here we demonstrate the utility of PFM for failure analysis of a multilayered ceramic capacitor. Correlative imaging of topography and electrical signals revealed discontinuous structures in the device that likely had a direct effect on device performance. Spectroscopy was also performed at a specific piezoelectric region to measure domain properties, such as the electric field required to flip the polarization direction (coercive voltage).
关键词： topography,atomic force microscopy,multilayered ceramic capacitor,electromechanics,piezoelectric microscopy,polarization,failure analysis
更新于2025-09-23 15:23:52
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Effect of short-circuit stress on the degradation of the SiO2 dielectric in SiC power MOSFETs
摘要： This paper presents the impact of a short-circuit event on the gate reliability in planar SiC MOSFETs, which becomes more critical with increased junction temperature and higher bias voltages. The electrical waveforms indicate that a gate degradation mechanism takes place, showing a large gate leakage current that increases as the gate degrades more and more. A failure analysis has been performed on the degraded SiC MOSFET and then compared to the structure of a new device to identify possible defects/abnormalities. A Focused-Ion Beam cut is performed showing a number of differences in comparison to the new device: (i) cracks between the poly-silicon gate and aluminium source, (ii) metal particles near the source contact, and (iii) alterations in the top surface of the aluminium source. The defects have been correlated with the increase in gate-leakage current and drain-leakage current.
关键词： Focused-Ion Beam,Short circuit,Gate-oxide breakdown,Gate oxide,Degradation,Defects,Reliability,SiC MOSFET,Failure analysis,SEM
更新于2025-09-23 15:22:29
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Low Renal Oxygen Saturation at Near-Infrared Spectroscopy on the First Day of Life Is Associated with Developing Acute Kidney Injury in Very Preterm Infants
摘要： Background: Acute kidney injury (AKI) is a frequent complication in preterm infants, and the identification of early markers of renal hypoperfusion is a chief challenge in neonatal intensive care units. Objectives: To describe the association between early markers of cardiovascular function and renal perfusion with AKI occurrence in a cohort of preterm infants < 32 weeks’ gestation. Methods: 128 infants were prospectively included from birth to discharge. During the first day of life, we assessed cardiovascular function, systemic and organ blood flow by Doppler ultrasound, and monitored cerebral and renal regional oxygen saturation (rSO2) using near-infrared spectroscopy (NIRS). These measures were analyzed in relation to developing AKI and serum creatinine (SCr) peak from day 2 to 7 of life. Results: 12 of 128 infants presented with AKI (9.4%). SCr peak was 155.3 ± 30.2 μmol/L in infants with AKI versus 82.0 ± 16.5 in non-AKI infants (p < 0.001). Among all measures of cardiovascular function and renal perfusion, low mean cerebral and renal rSO2 during the first day of life and a low resistive index at renal artery Doppler were significantly associated with developing AKI. After adjustment for possible confounding factors, low renal rSO2 on the first day of life remained associated with a high SCr peak from day 2 to 7 of life. Conclusion: Low renal rSO2 values during the first day of life correlate with developing AKI in preterm infants < 32 weeks’ gestation. NIRS monitoring of renal function during adaptation seems promising, and its very early use after birth to detect kidney hemodynamic dysfunction deserves further investigations.
关键词： Acute renal failure,Neonatal intensive care,Postnatal adaptation,Near-infrared spectroscopy,Renal function,Extremely low-birth-weight infants,Renal hemodynamics,Premature newborns,Patent ductus arteriosus
更新于2025-09-23 15:22:29
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Soft Failure Localization in Elastic Optical Networks
摘要： Soft failure localization to early detect service level agreement violations is of paramount importance in elastic optical networks (EONs), while it allows anticipating possible hard failure events. Nowadays, effective and automated solutions for soft failure localization during lightpaths’ commissioning testing and operation are still missing. In this paper, we focus on presenting soft failure localization algorithms based on two different active monitoring techniques. First, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures during commissioning testing phase by elaborating the estimated bit-error rate (BER) values provided by low-cost optical testing channel (OTC) modules. Second, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures during lightpath operation using cost-effective optical spectrum analyzers (OSAs) widely deployed in network nodes. Results are presented to validate both algorithms in the event of several soft failures affecting lasers and filters.
关键词： machine learning algorithms,soft failure localization,monitoring and data analytics
更新于2025-09-23 15:22:29
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Apply DFT Integrated Enhanced EBAC Methodology on Defect Isolations
摘要： Design for test (DFT) has been widely applied to digital circuit failure analysis (FA) in semiconductor industries. The FA methods based on DFT involve layer-by-layer checks using a polisher and an SEM for defect identification and localization. Yet these methods have limitations with high risks of sample damages. Besides, they are highly dependent on the technical proficiencies of operators and, thus, they are not effective for precise defect isolations. This problem has been aggravated, especially at advanced nodes. The nano-probing electron beam absorbed current (EBAC) has significant advantages on precisely locating defects. This technique is to directly identify specific defects without layer-by-layer checks. Therefore, it can minimize sample damages during sample pretreatment. EBAC is an efficient technique to isolate the defects when the circuit is at the floating condition. Because the ground lines exist almost everywhere in a chip and they are for, e.g., electronic static discharge charge releases or connecting with sources for pickup, EBAC becomes a natural option for us. However, due to poor EBAC images, EBAC’s applications are restricted when the circuits under test have grounding paths. In this paper, we propose two enhanced EBAC analysis methods, based on the DFT and EBAC integrated system, for the defect isolations with grounded connections. It is the first time the DFT and EBAC integrated system is reported, and we successfully demonstrated EBAC applicability by real FA cases.
关键词： Design for test (DFT),Grounding line,Fault isolation,Electron beam absorbed current (EBAC),Failure analysis (FA)
更新于2025-09-23 15:21:21
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The Generated Entropy Monitored by Pyroelectric Sensors
摘要： Entropy generation in irreversible processes is a critical issue that affects the failure and aging of electrical, chemical or mechanical systems. The promotion of energy conversion ef?ciency needs to reduce energy losses, namely to decrease entropy generation. A pyroelectric type of entropy detector is proposed to monitor energy conversion processes in real time. The entropy generation rate can be derived from the induced pyroelectric current, temperature, thermal capacity, pyroelectric coef?cient and electrode area. It is pro?table to design entropy detectors to maintain a small thermal capacity while pyroelectric sensors minimize geometrical dimensions. Moreover, decreasing the electrode area of the PZT cells could avoid affecting the entropy variation of the measured objects, but the thickness of the cells has to be greatly reduced to promote the temperature variation rate and strengthen the electrical signals. A commercial capacitor with a capacitance of 47 μF and a maximum endured voltage of 4 V were used to estimate the entropy to act as an indicator of the capacitors’ time-to-failure. The threshold time was evaluated by using the entropy generation rates at about 7.5 s, 11.25 s, 20 s and 30 s for the applied voltages of 40 V, 35 V, 30 V and 25 V respectively, while using a PZT cell with dimensions of 3 mm square and a thickness of 200 μm.
关键词： sensor,entropy,energy conversion,pyroelectric effect,failure
更新于2025-09-23 15:21:21
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Modeling and Simulation of Comprehensive Diode Behavior under Electrostatic Discharge Stresses
摘要： Diodes are effective devices for Electrostatic Discharge (ESD) protection. To accurately predict ESD robustness through circuit simulation of protection architectures in integrated circuits that use diodes, an enhanced model is proposed. This model is constructed with several compact model elements to simulate all physical device behaviors under high current transient ESD conditions, namely voltage overshoot, on-resistance variation, and thermal failure. The proposed model implements a thermal monitor, which can not only correlate current – voltage characteristics with the self-heating effect, but accurately predicts thermal failure under different pulse width conditions. The simulation results of this comprehensive diode model benchmarked against measurements are also reported.
关键词： junction thermal failure,Electrostatic discharge (ESD),thermal network,transmission line pulse (TLP),on-resistance variation,overshoot
更新于2025-09-23 15:21:21
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Effectively reducing the switching voltages based on CdS/ZnO heterostructure for resistive switching memory
摘要： Due to the two-terminal structure, non-destructive read and high integrable density, resistive switching random access memory (RRAM) has attracted much attention for its potential applications in semiconductor industry. Unfortunately, the unexpected failure behaviour is an obstacle for further applications. In our previous work, the CdS inter-layer was used to successfully suppress the failure behaviour in Cu2O based memory cell. However, the switching voltages are still too high and need to be signi?cantly reduced for further applications. In this work, the CdS/ZnO heterostructure is exploited to e?ectively reduce the switching voltages. Compared to the CdS/Cu2O based device, the switching voltages in Pt/CdS/ZnO/FTO cell are e?ectively reduced. The Pt/CdS/ZnO/FTO cell also exhibits remarkable resistive switching and stable data retention characteristics. This work proposes a feasible way to e?ectively optimize the RRAM devices for future applications.
关键词： CdS/ZnO,Switching voltages,Failure behaviours,Resistive switching
更新于2025-09-23 15:21:21
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[IEEE 2020 International Conference on Computing, Networking and Communications (ICNC) - Big Island, HI, USA (2020.2.17-2020.2.20)] 2020 International Conference on Computing, Networking and Communications (ICNC) - On Performance of Multiuser Underwater Wireless Optical Communication Systems
摘要： This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated power cycling test setup is given. Then, an improved in situ junction temperature estimation method using on-state collector–emitter voltage VC E O N and load current is proposed. In addition, a procedure of advanced accelerated power cycling test and test results with 600 V, 30 A transfer molded IGBT modules are presented in order to verify the validity and effectiveness of the proposed apparatus and methodology. Finally, physics-of-failure analysis of tested IGBT modules is provided.
关键词： power cycling test,physics-of-failure,Failure mechanism,lifetime model,insulated-gate bipolar transistor module,reliability
更新于2025-09-23 15:21:01