15 results on '"Chih-Chieh Chiang"'
Search Results
2. Intelligent control scheme for output efficiency improvement of parallel inverters.
- Author
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Wei-Hao Huang, Shu-Hung Liao, Jen-Hao Teng, Ting-Yen Hsieh, Bo-Ren Lan, and Chih-Chieh Chiang
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- 2016
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Catalog
3. Smart Control Strategy for Conversion Efficiency Enhancement of Parallel Inverters at Light Loads.
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Jen-Hao Teng, Shu-Hung Liao, Wei-Hao Huang, and Chih-Chieh Chiang
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- 2016
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4. Enhancing Thermoelectric Properties of 2D Bi2Se3 by 1D Texturing with Graphene
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Jen-Kai Wu, Sheng-Kuei Chiu, Szu-Hua Chen, Zhi-Long Yen, Ssu-Yen Huang, Yi-Ru Luo, Mario Hofmann, Yuan Huei Chang, Ya-Ping Hsieh, Wen-Pin Hsieh, and Chih-Chieh Chiang
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Materials science ,Graphene ,Phonon ,business.industry ,Energy Engineering and Power Technology ,Thermoelectric materials ,law.invention ,Thermal conductivity ,law ,Thermoelectric effect ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Tellurium compounds - Abstract
Two-dimensional (2D) thermoelectrics have shown enhanced performance compared to bulk thermoelectrics but cannot easily be improved through nanostructuring, since phonon-boundary-scattering becomes... more...
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- 2019
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5. Time of flight dual photon emission computed tomography
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Yu-Ching Ni, Keh-Shih Chuang, Meei-Ling Jan, Chih-Chieh Chiang, Chun-Chao Chuang, and Hsin-Hon Lin
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Radionuclide imaging ,Image quality ,Physics::Medical Physics ,Monte Carlo method ,lcsh:Medicine ,Article ,Coincidence ,Imaging phantom ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Optics ,Medical imaging ,Positron emission ,lcsh:Science ,Tomography ,Physics ,Multidisciplinary ,business.industry ,lcsh:R ,Detector ,030220 oncology & carcinogenesis ,lcsh:Q ,business - Abstract
Time-of-flight dual photon emission computed tomography (TOF-DuPECT) is an imaging system that can obtain radionuclide distributions using time information recorded from two cascade-decay photons. The potential decay locations in the image space, a hyperbolic response curve, can be determined via time-difference-of-arrival (TDOA) estimations from two instantaneous coincidence photons. In this feasibility study, Monte Carlo simulations were performed to generate list-mode coincidence data. A full-ring positron emission tomography-like detection system geometry was built in the simulation environment. A contrast phantom and a Jaszczak-like phantom filled with Selenium-75 (Se-75) were used to evaluate the image quality. A TOF-DuPECT system with varying coincidence time resolution (CTR) was then evaluated. We used the stochastic origin ensemble (SOE) algorithm to reconstruct images from the recorded list-mode data. The results indicate that the SOE method can be successfully employed for the TOF-DuPECT system and can achieve acceptable image quality when the CTR is less than 100 ps. Therefore, the TOF-DuPECT imaging system is feasible. With the improvement of the detector with time, future implementations and applications of TOF-DuPECT are promising. Further quantitative imaging techniques such as attenuation and scatter corrections for the TOF-DuPECT system will be developed in future. more...
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- 2020
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6. Optical and thermal simulations for the design of optodes for minimally invasive optogenetics stimulation or photomodulation of deep and large cortical areas in non-human primate brain
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A, Dubois, Chih-Chieh, Chiang, F, Smekens, S, Jan, V, Cuplov, S, Palfi, Keh-Shih, Chuang, S, Senova, and F, Pain
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Cerebral Cortex ,Mineral Fibers ,Optogenetics ,Primates ,Hot Temperature ,Opsins ,Physical Stimulation ,Motor Cortex ,Animals ,Computer Simulation ,Monte Carlo Method ,Photic Stimulation - Abstract
The use of optogenetics or photobiomodulation in non-human primate (NHP) requires the ability to noninvasively stimulate large and deep cortical brain tissues volumes. In this context, the optical and geometrical parameters of optodes are critical. Methods and general guidelines to optimize these parameters have to be defined.We propose the design of an optode for safe and efficient optical stimulation of a large volume of NHP cortex, down to 3-5 mm depths without inserting fibers into the cortex.Monte Carlo simulations of optical and thermal transport have been carried out using the Geant4 application for tomographic emission (GATE) platform. Parameters such as the fiber diameter, numerical aperture, number of fibers and their geometrical arrangement have been studied. Optimal hardware parameters are proposed to obtain homogeneous fluence above the fluence threshold for opsin activation without detrimental thermal effects.The simulations show that a large fiber diameter and a large numerical aperture are preferable since they allow limiting power concentration and hence the resulting thermal increases at the brain surface. To obtain a volume of 200-500 mmThe present study defines a method to optimize the design of optode and the choice of stimulation parameters for optogenetics and more generally light delivery to deep and large volumes of tissues in NHP brain with a controlled irradiance dosimetry. The general guidelines are the use of silica fibers with a large numerical aperture and a large diameter. The combination of several fibers is required if large volumes need to be stimulated while avoiding thermal effects. more...
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- 2018
7. Erratum: Experimental assessment of the safety and potential efficacy of high irradiance photostimulation of brain tissues
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Suhan Senova, Ilona Scisniak, Chih-Chieh Chiang, Isabelle Doignon, Stéphane Palfi, Antoine Chaillet, Claire Martin, and Frédéric Pain
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Multidisciplinary ,Article - Abstract
Optogenetics is widely used in fundamental neuroscience. Its potential clinical translation for brain neuromodulation requires a careful assessment of the safety and efficacy of repeated, sustained optical stimulation of large volumes of brain tissues. This study was performed in rats and not in non-human primates for ethical reasons. We studied the spatial distribution of light, potential damage, and non-physiological effects in vivo, in anesthetized rat brains, on large brain volumes, following repeated high irradiance photo-stimulation. We generated 2D irradiance and temperature increase surface maps based on recordings taken during optical stimulation using irradiance and temporal parameters representative of common optogenetics experiments. Irradiances of 100 to 600 mW/mm2 with 5 ms pulses at 20, 40, and 60 Hz were applied during 90 s. In vivo electrophysiological recordings and post-mortem histological analyses showed that high power light stimulation had no obvious phototoxic effects and did not trigger non-physiological functional activation. This study demonstrates the ability to illuminate cortical layers to a depth of several millimeters using pulsed red light without detrimental thermal damages. more...
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- 2017
8. Experimental assessment of the safety and potential efficacy of high irradiance photostimulation of brain tissues
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Claire Martin, Frédéric Pain, Suhan Senova, Stéphane Palfi, Antoine Chaillet, Chih-Chieh Chiang, Ilona Scisniak, Isabelle Doignon, Institut Mondor de Recherche Biomédicale (IMRB), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-IFR10, Groupe Henri Mondor-Albert Chenevier, Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Henri Mondor-Hôpital Albert Chenevier, Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC (UMR_8165)), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Warsaw (UW), National Tsing Hua University [Hsinchu] (NTHU), Intéractions cellulaires et physiopathologie hépathique (Orsay, Essonne) UMRS 1174 (ICPH ), Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire des signaux et systèmes (L2S), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Unité de Biologie Fonctionnelle et Adaptative (BFA (UMR_8251 / U1133)), Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), ANR-13-JS03-0006,SYNCHNEURO,Théorie de la commande pour la synchronisation neuronale: modélisation à partir de données l'optogénétique, et alteration boucle-fermée des oscillations cérébrales pathologiques(2013), Laboratoire des signaux et systèmes ( L2S ), Université Paris-Sud - Paris 11 ( UP11 ) -CentraleSupélec-Centre National de la Recherche Scientifique ( CNRS ), Imagerie et Modélisation en Neurobiologie et Cancérologie ( IMNC ), Centre National de la Recherche Scientifique ( CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Paris-Sud - Paris 11 ( UP11 ), PAIN, FREDERIC, Jeunes Chercheuses et Jeunes Chercheurs - Théorie de la commande pour la synchronisation neuronale: modélisation à partir de données l'optogénétique, et alteration boucle-fermée des oscillations cérébrales pathologiques - - SYNCHNEURO2013 - ANR-13-JS03-0006 - JC - VALID, Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR10-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) more...
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0301 basic medicine ,Hot Temperature ,[SPI.OPTI] Engineering Sciences [physics]/Optics / Photonic ,Light ,[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Irradiance ,Biology ,Optogenetics ,Photostimulation ,[ SDV.IB.MN ] Life Sciences [q-bio]/Bioengineering/Nuclear medicine ,Translational Research, Biomedical ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,medicine ,Animals ,Rats, Wistar ,ComputingMilieux_MISCELLANEOUS ,[ SDV.IB.IMA ] Life Sciences [q-bio]/Bioengineering/Imaging ,Cerebral Cortex ,Neurons ,Multidisciplinary ,High irradiance ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Neuromodulation (medicine) ,Electrophysiology ,030104 developmental biology ,medicine.anatomical_structure ,[SDV.IB.IMA] Life Sciences [q-bio]/Bioengineering/Imaging ,Cerebral cortex ,[ SDV.NEU.NB ] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic ,[ SPI.OPTI ] Engineering Sciences [physics]/Optics / Photonic ,Erratum ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
Optogenetics is widely used in fundamental neuroscience. Its potential clinical translation for brain neuromodulation requires a careful assessment of the safety and efficacy of repeated, sustained optical stimulation of large volumes of brain tissues. This study was performed in rats and not in non-human primates for ethical reasons. We studied the spatial distribution of light, potential damage, and non-physiological effects in vivo, in anesthetized rat brains, on large brain volumes, following repeated high irradiance photo-stimulation. We generated 2D irradiance and temperature increase surface maps based on recordings taken during optical stimulation using irradiance and temporal parameters representative of common optogenetics experiments. Irradiances of 100 to 600 mW/mm2 with 5 ms pulses at 20, 40, and 60 Hz were applied during 90 s. In vivo electrophysiological recordings and post-mortem histological analyses showed that high power light stimulation had no obvious phototoxic effects and did not trigger non-physiological functional activation. This study demonstrates the ability to illuminate cortical layers to a depth of several millimeters using pulsed red light without detrimental thermal damages. more...
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- 2017
- Full Text
- View/download PDF
9. A noise smoothing origin ensemble algorithm based on local filtering
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Chih-Chieh Chiang, Yu-Ching Ni, Meei-Ling Jan, Keh-Shih Chuang, and Hsin-Hon Lin
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Radiological and Ultrasound Technology ,Phantoms, Imaging ,Image quality ,Computer science ,Image processing ,Reconstruction algorithm ,Filter (signal processing) ,Iterative reconstruction ,Signal-To-Noise Ratio ,computer.software_genre ,Imaging phantom ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Kernel (image processing) ,Voxel ,030220 oncology & carcinogenesis ,Image Processing, Computer-Assisted ,Humans ,Radiology, Nuclear Medicine and imaging ,computer ,Algorithm ,Algorithms ,Smoothing ,Probability - Abstract
An origin ensemble (OE) image reconstruction algorithm can be used for the fast reconstruction of unconventional geometrical images, e.g. in a Compton camera (CC) system. Due to the low-count rate in the emission data, the reconstructed image is often noisy and inhomogeneous in density. In this study, we propose a way to smooth out the noise in the OE algorithm. During the OE reconstruction, the algorithm stochastically modifies the current location to a random new voxel along the probable corresponding curve of each event depending on the relative event density of the new and old locations. In the original OE technique, the event density is simply the number of events in the voxel. In the proposed method, the event density is estimated from the filtering of a kernel window centered on the voxel. Incorporating the regional filtering is similar to performing an OE algorithm on a smoothed image at each iteration and enables the reconstruction of a smoother image. A Flangeless Esser PET phantom and a multi-activity phantom are used to study the property of the new reconstruction algorithm. The results indicate that the proposed method performs better than a conventional OE algorithm in terms of normalized mean square error (NMSE) and structural similarity (SSIM). Both contrast noise ratio (CNR) and reconstruction accuracy of the new method are better than the conventional OE algorithm and their performances improve with the increase of object size. The median-OE possesses the highest overall image quality and recovery rate among the three filter-OE algorithms and is the method of choice for image reconstruction. Comparing to conventional post-smoothing OEs, the NMSE of median-OE improves 57.6% (46.9%) and the SSIM increased by 73.2% (51.1%) for the Esser (multi-activity) phantom. The proposed OE algorithm is simple and efficient for noise smoothing without complex calculations and highly suited for low-count cases. more...
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- 2019
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10. Experimental assessment of thermal effects of high power density light stimulation for optogenetics control of deep brain structures (Conference Presentation)
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Isabelle Doignon, Antoine Chaillet, Claire Martin, Chih Chieh Chiang, Suhan Senova, Stéphane Palfi, Ilona Scisniak, and Frédéric Pain
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Optical fiber ,Materials science ,business.industry ,Attenuation ,LIGHT STIMULATION ,High power density ,Blood flow ,Optogenetics ,Cooling effect ,law.invention ,Optics ,law ,business ,Biomedical engineering - Abstract
2D surface maps of light distribution and temperature increase were recorded in wild type anesthetized rats brains during 90s light stimulation at 478nm (blue) and 638nm (red) with continuous or pulsed optical stimulations with corresponding power ranging from 100 up to 1200 mW/mm² at the output of an optical fiber. Post mortem maps were recorded in the same animals to assess the cooling effect of blood flow. Post mortem histological analysis were carried out to assess whether high power light stimulations had phototoxic effects or could trigger non physiological functional activation. Temperature increase remains below physiological changes (0,5 -1°) for stimulations up to 400mW/mm² at 40Hz. . Histology did not show significant irreversible modifications or damage to the tissues. The spatial profile of light distribution and heat were correlated and demonstrate as expected a rapid attenuation with diatnce to the fiber. more...
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- 2016
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11. An innovative numerical approach to resolve the pulse wave velocity in a healthy thoracic aorta model
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Chih Chieh Chiang, Wen-Yih Isaac Tseng, Hsi-Yu Yu, Chih-yung Wen, An-Shik Yang, and Li Yu Tseng
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Adult ,Male ,Models, Anatomic ,medicine.medical_specialty ,Biomedical Engineering ,Hemodynamics ,Aorta, Thoracic ,Bioengineering ,Pulse Wave Analysis ,medicine.artery ,Internal medicine ,Fluid–structure interaction ,medicine ,Humans ,Thoracic aorta ,Pulse wave velocity ,Aortic dissection ,Physics ,General Medicine ,Blood flow ,medicine.disease ,Magnetic Resonance Imaging ,Computer Science Applications ,Human-Computer Interaction ,Compliance (physiology) ,Circulatory system ,cardiovascular system ,Cardiology ,Compliance ,Biomedical engineering - Abstract
Aortic dissection and atherosclerosis are highly fatal diseases. The development of both diseases is closely associated with highly complex haemodynamics. Thus, in predicting the onset of cardiac disease, it is desirable to obtain a detailed understanding of the flowfield characteristics in the human cardiovascular circulatory system. Accordingly, in this study, a numerical model of a normal human thoracic aorta is constructed using the geometry information obtained from a phase-contrast magnetic resonance imaging (PC-MRI) technique. The interaction between the blood flow and the vessel wall dynamics is then investigated using a coupled fluid-structure interaction (FSI) analysis. The simulations focus specifically on the flowfield characteristics and pulse wave velocity (PWV) of the blood flow. Instead of using a conventional PC-MRI method to measure PWV, we present an innovative application of using the FSI approach to numerically resolve PWV for the assessment of wall compliance in a thoracic aorta model. The estimated PWV for a normal thoracic aorta agrees well with the results obtained via PC-MRI measurement. In addition, simulations which consider the FSI effect yield a lower predicted value of the wall shear stress at certain locations in the cardiac cycle than models which assume a rigid vessel wall. Consequently, the model provides a suitable basis for the future development of more sophisticated methods capable of performing the computer-aided analysis of aortic blood flows. more...
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- 2012
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12. Simulation of multi-photon emission isotopes using time-resolved SimSET multiple photon history generator
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Meei-Ling Jan, Chang-Shiun Lin, Hsin-Hon Lin, Keh-Shih Chuang, and Chih-Chieh Chiang
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Physics ,medicine.medical_specialty ,Radionuclide ,Generator (computer programming) ,Photon ,Decay scheme ,Photon emission ,Isotope ,Monte Carlo method ,medicine ,Energy level ,Medical physics ,Computational physics - Abstract
Multiple-photon emitters, such as In-111 or Se-75, have enormous potential in the field of nuclear medicine imaging. For example, Se-75 can be used to investigate the bile acid malabsorption and measure the bile acid pool loss. The simulation system for emission tomography (SimSET) is a well-known Monte Carlo simulation (MCS) code in nuclear medicine for its high computational efficiency. However, current SimSET cannot simulate these isotopes due to the lack of modeling of complex decay scheme and the time-dependent decay process. To extend the versatility of SimSET for simulation of those multi-photon emission isotopes, a time-resolved multiple photon history generator based on SimSET codes is developed in present study. For developing the time-resolved SimSET (trSimSET) with radionuclide decay process, the new MCS model introduce new features, including decay time information and photon time-of-flight information, into this new code. The half-life of energy states were tabulated from the Evaluated Nuclear Structure Data File (ENSDF) database. The MCS results indicate that the overall percent difference is less than 6.1% for all simulation trials as compared to GATE. To sum up, we demonstrated that time-resolved SimSET multiple photon history generator can have comparable accuracy with GATE and keeping better computational efficiency. The new MCS code is very useful to study the multi-photon imaging of novel isotopes that needs the simulation of lifetime and the time-of-flight measurements. more...
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- 2015
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13. Enhancing Thermoelectric Properties of 2D Bi2Se3 by 1D Texturing with Graphene.
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Jen-Kai Wu, Hofmann, Mario, Wen-Pin Hsieh, Szu-Hua Chen, Zhi-Long Yen, Sheng-Kuei Chiu, Yi-Ru Luo, Chih-Chieh Chiang, Ssu-Yen Huang, Yuan-Huei Chang, and Ya-Ping Hsieh
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- 2019
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14. SU-G-IeP4-14: Prostate Brachytherapy Activity Measurement and Source Localization by Using a Dual Photon Emission Computed Tomography System: A Feasibility Study
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Chang-Shiun Lin, Hsin-Hon Lin, Chih-Chieh Chiang, Yao Chou Tsai, and Keh-Shih Chuang
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Physics ,medicine.diagnostic_test ,business.industry ,medicine.medical_treatment ,Brachytherapy ,food and beverages ,Centroid ,General Medicine ,Collimated light ,Imaging phantom ,Optics ,medicine ,Coincidence circuit ,Dosimetry ,business ,Prostate brachytherapy ,Emission computed tomography - Abstract
Purpose: To monitor the activity distribution and needle position during and after implantation in operating rooms. Methods: Simulation studies were conducted to assess the feasibility of measurement activity distribution and seed localization using the DuPECT system. The system consists of a LaBr3-based probe and planar detection heads, a collimation system, and a coincidence circuit. The two heads can be manipulated independently. Simplified Yb-169 brachytherapy seeds were used. A water-filled cylindrical phantom with a 40-mm diameter and 40-mm length was used to model a simplified prostate of the Asian man. Two simplified seeds were placed at a radial distance of 10 mm and tangential distance of 10 mm from the center of the phantom. The probe head was arranged perpendicular to the planar head. Results of various imaging durations were analyzed and the accuracy of the seed localization was assessed by calculating the centroid of the seed. Results: The reconstructed images indicate that the DuPECT can measure the activity distribution and locate the seeds dwelt in different positions intraoperatively. The calculated centroid on average turned out to be accurate within the pixel size of 0.5 mm. The two sources were identified when the duration is longer than 15 s. The sensitivity measured in water was merely 0.07 cps/MBq. Conclusion: Preliminary results show that the measurement of the activity distribution and seed localization are feasible using the DuPECT system intraoperatively. It indicates the DuPECT system has potential to be an approach for dose-distribution-validation. The efficacy of acvtivity distribution measurement and source localization using the DuPECT system will evaluated in more realistic phantom studies (e.g., various attenuation materials and greater number of seeds) in the future investigation. more...
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- 2016
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15. Experimental assessment of the safety and potential efficacy of high irradiance photostimulation of brain tissues.
- Author
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Suhan, Senova, Ilona, Scisniak, Chih-Chieh, Chiang, Isabelle, Doignon, Stéphane, Palfi, Antoine, Chaillet, Claire, Martin, and Frédéric, Pain
- Abstract
Optogenetics is widely used in fundamental neuroscience. Its potential clinical translation for brain neuromodulation requires a careful assessment of the safety and efficacy of repeated, sustained optical stimulation of large volumes of brain tissues. This study was performed in rats and not in non-human primates for ethical reasons. We studied the spatial distribution of light, potential damage, and non-physiological effects in vivo, in anesthetized rat brains, on large brain volumes, following repeated high irradiance photo-stimulation. We generated 2D irradiance and temperature increase surface maps based on recordings taken during optical stimulation using irradiance and temporal parameters representative of common optogenetics experiments. Irradiances of 100 to 600 mW/mm
2 with 5 ms pulses at 20, 40, and 60 Hz were applied during 90 s. In vivo electrophysiological recordings and post-mortem histological analyses showed that high power light stimulation had no obvious phototoxic effects and did not trigger non-physiological functional activation. This study demonstrates the ability to illuminate cortical layers to a depth of several millimeters using pulsed red light without detrimental thermal damages. [ABSTRACT FROM AUTHOR] more...- Published
- 2017
- Full Text
- View/download PDF
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