arXiv: Medical Physics最新文献_第2页

Portable Magnetometry for Detection of Biomagnetism in Ambient Environments 用于环境中生物磁性检测的便携式磁强计

arXiv: Medical Physics Pub Date : 2020-01-07 DOI: 10.1103/physrevapplied.14.011002

M. Limes, E. Foley, T. Kornack, S. Caliga, S. McBride, A. Braun, W. Lee, V. Lucivero, M. Romalis

{"title":"Portable Magnetometry for Detection of Biomagnetism in Ambient Environments","authors":"M. Limes, E. Foley, T. Kornack, S. Caliga, S. McBride, A. Braun, W. Lee, V. Lucivero, M. Romalis","doi":"10.1103/physrevapplied.14.011002","DOIUrl":"https://doi.org/10.1103/physrevapplied.14.011002","url":null,"abstract":"We present a method of optical magnetometry with parts-per-billion resolution that is able to detect biomagnetic signals generated from the human brain and heart in Earth's ambient environment. Our magnetically silent sensors measure the total magnetic field by detecting the free-precession frequency of highly spin-polarized alkali metal vapor. A first-order gradiometer is formed from two magnetometers that are separated by a 3 cm baseline. Our gradiometer operates from a laptop consuming 5 W over a USB port, enabled by state-of-the-art micro-fabricated alkali vapor cells, advanced thermal insulation, custom electronics, and laser packages within the sensor head. The gradiometer obtains a sensitivity of 16 fT/cm/Hz$^{1/2}$ outdoors, which we use to detect neuronal electrical currents and magnetic cardiography signals. Recording of neuronal magnetic fields is one of a few available methods for non-invasive functional brain imaging that usually requires extensive magnetic shielding and other infractructure. This work demonstrates the possibility of a dense array of portable biomagnetic sensors that are deployable in a variety of natural environments.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77582676","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}

引用次数: 79

An accelerometer-only algorithm for determining the acceleration field of a rigid body, with application in studying the mechanics of mild traumatic brain injury 一种确定刚体加速度场的纯加速度计算法，并在轻度颅脑损伤力学研究中应用

arXiv: Medical Physics Pub Date : 2019-11-21 DOI: 10.1016/j.jmps.2020.104014

Mohammad Masiur Rahaman, Wenqiang Fang, A. Fawzi, Yang Wan, H. Kesari

引用次数: 7

A Feasibility Study on Deep Learning-Based Radiotherapy Dose Calculation 基于深度学习的放疗剂量计算可行性研究

arXiv: Medical Physics Pub Date : 2019-08-08 DOI: 10.1002/MP.13953

Yixun Xing, D. Nguyen, W. Lu, Ming Yang, Steve B. Jiang

{"title":"A Feasibility Study on Deep Learning-Based Radiotherapy Dose Calculation","authors":"Yixun Xing, D. Nguyen, W. Lu, Ming Yang, Steve B. Jiang","doi":"10.1002/MP.13953","DOIUrl":"https://doi.org/10.1002/MP.13953","url":null,"abstract":"Purpose: Various dose calculation algorithms are available for radiation therapy for cancer patients. However, these algorithms are faced with the tradeoff between efficiency and accuracy. The fast algorithms are generally less accurate, while the accurate dose engines are often time consuming. In this work, we try to resolve this dilemma by exploring deep learning (DL) for dose calculation. Methods: We developed a new radiotherapy dose calculation engine based on a modified Hierarchically Densely Connected U-net (HD U-net) model and tested its feasibility with prostate intensity-modulated radiation therapy (IMRT) cases. Mapping from an IMRT fluence map domain to a 3D dose domain requires a deep neural network of complicated architecture and a huge training dataset. To solve this problem, we first project the fluence maps to the dose domain using a modified ray-tracing algorithm, and then we use the HD U-net to map the ray-tracing dose distribution into an accurate dose distribution calculated using a collapsed cone convolution/superposition (CS) algorithm. Results: It takes about one second to compute a 3D dose distribution for a typical 7-field prostate IMRT plan, which can be further reduced to achieve real-time dose calculation by optimizing the network. For all eight testing patients, evaluation with Gamma Index and various clinical goals for IMRT optimization shows that the DL dose distributions are clinically identical to the CS dose distributions. Conclusions: We have shown the feasibility of using DL for calculating radiotherapy dose distribution with high accuracy and efficiency.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85784281","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}

引用次数: 37

Single-Shot X-Ray Speckle-Based Imaging of a Single-Material Object 单一材料物体的单次x射线散斑成像

arXiv: Medical Physics Pub Date : 2019-07-31 DOI: 10.1103/PHYSREVAPPLIED.13.054023

K. Pavlov, H. Li, D. Paganin, S. Berujon, H'elene Roug'e-Labriet, E. Brun

引用次数: 24

Navigated interventions in the head and neck area: standardized assessment of a new handy field generator. 头部和颈部区域的导航干预:一种新的便携式磁场发生器的标准化评估。

arXiv: Medical Physics Pub Date : 2019-03-24 DOI: 10.1007/978-3-658-25326-4_53

B. Mittmann, A. Seitel, L. Maier-Hein, A. Franz

引用次数: 0

SURE-based Automatic Parameter Selection For ESPIRiT Calibration 基于sure的自动参数选择用于spirit校准

arXiv: Medical Physics Pub Date : 2018-11-14 DOI: 10.1002/MRM.2838

S. Iyer, Frank Ong, M. Doneva, M. Lustig

{"title":"SURE-based Automatic Parameter Selection For ESPIRiT Calibration","authors":"S. Iyer, Frank Ong, M. Doneva, M. Lustig","doi":"10.1002/MRM.2838","DOIUrl":"https://doi.org/10.1002/MRM.2838","url":null,"abstract":"Purpose: Parallel imaging methods in MRI have resulted in faster acquisition times and improved noise performance. ESPIRiT is one such technique that estimates coil sensitivity maps from the auto-calibration region using an eigenvalue-based method. This method requires choosing several parameters for the the map estimation. Even though ESPIRiT is fairly robust to these parameter choices, occasionally, poor selection can result in reduced performance. The purpose of this work is to automatically select parameters in ESPIRiT for more robust and consistent performance across a variety of exams. \u0000Theory and Methods: Stein's unbiased risk estimate (SURE) is a method of calculating an unbiased estimate of the mean squared error of an estimator under certain assumptions. We show that this can be used to estimate the performance of ESPIRiT. We derive and demonstrate the use of SURE to optimize ESPIRiT parameter selection. \u0000Results: Simulations show SURE to be an accurate estimator of the mean squared error. SURE is then used to optimize ESPIRiT parameters to yield maps that are optimal in a denoising/data-consistency sense. This improves g-factor performance without causing undesirable attenuation. In-vivo experiments verify the reliability of this method. \u0000Conclusion: Simulation experiments demonstrate that SURE is an accurate estimate of expected mean squared error. Using SURE to determine ESPIRiT parameters allows for automatic parameter this http URL-vivo results are consistent with simulation and theoretical results.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84987972","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}

引用次数: 9

Structural Dynamics and Evolution of Capsule Endoscopy (Pill Camera) Technology in Gastroenterologist Assertion 胃肠病学家断言胶囊内窥镜(药丸相机)技术的结构动力学和演变

arXiv: Medical Physics Pub Date : 2018-04-02 DOI: 10.5121/ijfcst.2018.8201

Maxwell Scale Uwadia Osagie, O. Enagbonma, Amanda Iriagbonse Inyang

引用次数: 3

In vivo high resolution human retinal imaging with wavefront correctionless full-field OCT 无波前校正的全视野OCT在体内高分辨率人眼视网膜成像

arXiv: Medical Physics Pub Date : 2018-01-24 DOI: 10.1364/OPTICA.5.000409

P. Xiao, V. Mazlin, K. Grieve, J. Sahel, M. Fink, A. Boccara

引用次数: 32

Investigation of the energy shielding of kidney stones by cavitation bubble clouds during burst wave lithotripsy 爆破波碎石中空化气泡云对肾结石能量屏蔽的研究

arXiv: Medical Physics Pub Date : 2018-01-21 DOI: 10.1115/1.861851_ch119

K. Maeda, A. Maxwell, W. Kreider, T. Colonius, M. Bailey

{"title":"Investigation of the energy shielding of kidney stones by cavitation bubble clouds during burst wave lithotripsy","authors":"K. Maeda, A. Maxwell, W. Kreider, T. Colonius, M. Bailey","doi":"10.1115/1.861851_ch119","DOIUrl":"https://doi.org/10.1115/1.861851_ch119","url":null,"abstract":"We conduct experiments and numerical simulations of the dynamics of bubble clouds nucleated on the surface of an epoxy cylindrical stone model during burst wave lithotripsy (BWL). In the experiment, the bubble clouds are visualized and bubble-scattered acoustics are measured. In the numerical simulation, we combine methods for modeling compressible multicomponent flows to capture complex interactions among cavitation bubbles, the stone, and the burst wave. Quantitative agreement is confirmed between results of the experiment and the simulation. We observe and quantify a significant shielding of incident wave energy by the bubble clouds. The magnitude of shielding reaches up to 80% of the total acoustic energy of the incoming burst wave, suggesting a potential loss of efficacy of stone comminution. We further discovered a strong linear correlation between the magnitude of the energy shielding and the amplitude of the bubble-scattered acoustics, independent of the initial size and the void fraction of the bubble cloud within a range addressed in the simulation. This correlation could provide for real-time monitoring of cavitation activity in BWL.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74305090","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}

引用次数: 4

Non-invasive Evaluation of Aortic Stiffness Dependence with Aortic Blood Pressure and Internal Radius by Shear Wave Elastography and Ultrafast Imaging 横波弹性成像和超快成像无创评价主动脉硬度与主动脉血压和内半径的相关性

arXiv: Medical Physics Pub Date : 2017-12-01 DOI: 10.1016/j.irbm.2017.12.001

C. Papadacci, T. Mirault, B. Dizier, M. Tanter, E. Messas, M. Pernot

引用次数: 0