- Pulse Pileup Analysis for a Double-Sided Silicon Strip Detector Using Variable Pulse Shapes IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2019; 66 (6): 960?68
- Preclinical testing of ultra-rapid FLASH total abdominal irradiation demonstrates survival benefit and decreased gastrointestinal toxicity compared to conventional external beam radiation. AMER SOC CLINICAL ONCOLOGY. 2019
Pulse pileup analysis for a double-sided silicon strip detector using variable pulse shapes.
IEEE transactions on nuclear science
2019; 66 (6): 960?68
Due to pulse pileup, photon counting detectors (PCDs) suffer from count loss and energy distortion when operating in high count rate environments. In this paper, we studied the pulse pileup of a double-sided silicon strip detector (DSSSD) to evaluate its potential application in a mammography system. We analyzed the pulse pileup using pulses of varied shapes, where the shape of the pulse depends on the location of photon interaction within the detector. To obtain the shaped pulses, first, transient currents for photons interacting at different locations were simulated using a Technology Computer-Aided Design (TCAD) software. Next, the currents were shaped by a CR-RC2 shaping circuit, calculated using Simulink. After obtaining these pulses, both the different orders of pileup and the energy spectrum were calculated by taking into account the following two factors: 1) spatial distribution of photon interactions within the detector, and 2) time interval distribution between successive photons under a given photon flux. We found that for a DSSSD with thickness of 300 ?m, pitch of 25 ?m and strip length of 1 cm, under a bias voltage of 50 V, the variable pulse shape model predicts the fraction free of pileup can be > 90 % under a photon flux of 3.75 Mcps/mm2. The double-sided silicon-strip detector is a promising candidate for digital mammography applications.
View details for DOI 10.1109/TNS.2019.2917144
View details for PubMedID 31327872
View details for PubMedCentralID PMC6640861
Reduced cognitive deficits after FLASH irradiation of whole mouse brain are associated with less hippocampal dendritic spine loss and neuroinflammation.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
To evaluate the impact of ultra-rapid FLASH mouse whole brain irradiation on hippocampal dendritic spines and neuroinflammation, factors associated with cognitive impairment after brain irradiation.We administered 30?Gy whole brain irradiation to C57BL6/J mice in sub-second (FLASH) vs. 240?s conventional delivery time keeping all other parameters constant, using a custom configured clinical linac. Ten weeks post-irradiation, we evaluated spatial and non-spatial object recognition using novel object location and object recognition testing. We measured dendritic spine density by tracing Golgi-stained hippocampal neurons and evaluated neuroinflammation by CD68 immunostaining, a marker of activated microglia, and expression of 10 pro-inflammatory cytokines using a multiplex immunoassay.At ten weeks post-irradiation, compared to unirradiated controls, conventional delivery time irradiation significantly impaired novel object location and recognition tasks whereas the same dose given in FLASH delivery did not. Conventional delivery time, but not FLASH, was associated with significant loss of dendritic spine density in hippocampal apical dendrites, with a similar non-significant trend in basal dendrites. Conventional delivery time was associated with significantly increased CD68-positive microglia compared to controls whereas FLASH was not. Conventional delivery time was associated with significant increases in 5 of 10 pro-inflammatory cytokines in the hippocampus (and non-significant increases in another 3), whereas FLASH was associated with smaller increases in only 3.Reduced cognitive impairment and associated neurodegeneration were observed with FLASH compared to conventional delivery time irradiation, potentially through decreased induction of neuroinflammation, suggesting a promising approach to increasing therapeutic index in radiation therapy of brain tumors.
View details for DOI 10.1016/j.radonc.2019.06.006
View details for PubMedID 31253467
- Bulk GaN alpha-particle detector with large depletion region and improved energy resolution NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2017; 849: 11-15
Thermal limits on MV x-ray production by bremsstrahlung targets in the context of novel linear accelerators.
2017; 44 (12): 6610?20
To study the impact of target geometrical and linac operational parameters, such as target material and thickness, electron beam size, repetition rate, and mean current on the ability of the radiotherapy treatment head to deliver high-dose-rate x-ray irradiation in the context of novel linear accelerators capable of higher repetition rates/duty cycle than conventional clinical linacs.The depth dose in a water phantom without a flattening filter and heat deposition in an x-ray target by 10 MeV pulsed electron beams were calculated using the Monte-Carlo code MCNPX, and the transient temperature behavior of the target was simulated by ANSYS. Several parameters that affect both the dose distribution and temperature behavior were investigated. The target was tungsten with a thickness ranging from 0 to 3 mm and a copper heat remover layer. An electron beam with full width at half maximum (FWHM) between 0 and3 mm and mean current of 0.05-2 mA was used as the primary beam at repetition rates of 100, 200, 400, and 800 Hz.For a 10 MeV electron beam with FWHM of 1 mm, pulse length of 5 ?s, by using a thin tungsten target with thickness of 0.2 mm instead of 1 mm, and by employing a high repetition rate of 800 Hz instead of 100 Hz, the maximum dose rate delivered can increase two times from 0.57 to 1.16 Gy/s. In this simple model, the limiting factor on dose rate is the copper heat remover's softening temperature, which was considered to be 500°C in our study.A high dose rate can be obtained by employing thin targets together with high repetition rate electron beams enabled by novel linac designs, whereas the benefit of thin targets is marginal at conventional repetition rates. Next generation linacs used to increase dose rate need different target designs compared to conventional linacs.
View details for PubMedID 28983960
View details for PubMedCentralID PMC5734638
- Review of using gallium nitride for ionizing radiation detection APPLIED PHYSICS REVIEWS 2015; 2 (3)
- Transient current analysis of a GaN radiation detector by TCAD NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2014; 761: 7-12
- Discharge characteristics of the DUHOCAMIS with a high magnetic bottle-shaped field CHINESE PHYSICS C 2014; 38 (10)
In Situ Quantification and Visualization of Lithium Transport with Neutrons
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2014; 53 (36): 9498-9502
A real-time quantification of Li transport using a nondestructive neutron method to measure the Li distribution upon charge and discharge in a Li-ion cell is reported. By using in?situ neutron depth profiling (NDP), we probed the onset of lithiation in a high-capacity Sn anode and visualized the enrichment of Li atoms on the surface followed by their propagation into the bulk. The delithiation process shows the removal of Li near the surface, which leads to a decreased coulombic efficiency, likely because of trapped Li within the intermetallic material. The developed in?situ NDP provides exceptional sensitivity in the temporal and spatial measurement of Li transport within the battery material. This diagnostic tool opens up possibilities to understand rates of Li transport and their distribution to guide materials development for efficient storage mechanisms. Our observations provide important mechanistic insights for the design of advanced battery materials.
View details for DOI 10.1002/anie.201404197
View details for Web of Science ID 000342677000013
View details for PubMedID 25044527
- Study of GaN Radiation Sensor After In-core Neutron Irradiation IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2014; 61 (4): 2040-2044
- Profiling lithium distribution in Sn anode for lithium-ion batteries with neutrons JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 2014; 301 (1): 277-284
- Evaluation of freestanding GaN as an alpha and neutron detector NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2013; 719: 13-16
- Design of triode extraction system for a dual hollow cathode ion source CHINESE PHYSICS C 2011; 35 (2): 193-198
Theoretical analysis of a new extraction system for a DUHOCAMIS operating in a high magnetic field
CHINESE PHYSICS C
2010; 34 (11): 1738-1741
View details for Web of Science ID 000284184500014