Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics最新文献_第5页

Analysis of three-dimensional software EIT (electrical impedance tomography) phantoms by the finite element method. 三维软件电阻抗层析成像的有限元分析。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/026

M Kuzuoglu, M Moh'dSaid, Y Z Ider

{"title":"Analysis of three-dimensional software EIT (electrical impedance tomography) phantoms by the finite element method.","authors":"M Kuzuoglu, M Moh'dSaid, Y Z Ider","doi":"10.1088/0143-0815/13/a/026","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/026","url":null,"abstract":"In electrical impedance tomography, two-dimensional (2D) finite element solutions are used in the imaging algorithms. It is assumed that a major part of the current flowing through the object is restricted to the measurement plane (i.e. the plane determined by the electrodes which are used for measuring voltage differences) and the current flowing elsewhere is negligible. However, there is usually a three-dimensional (3D) variation of the conductivity distribution and if there are regions of high contrast close to the measurement plane, the measured voltage values may be considerably affected. In this work a 3D finite element analysis is utilised to demonstrate the previously mentioned effects. Examples are given to show the measured voltage differences for conductivity distributions which are identical on the measurement plane but different elsewhere.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"135-8"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754874","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: 5

Electrical Impendance Tomography. 4th European Community workshop. York, 24-27 July 1991. 电阻抗断层扫描。第四届欧洲共同体研讨会。1991年7月24日至27日，约克。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01

引用次数: 0

Imaging the complex impedance in electrical impedance tomography. 电阻抗断层成像中的复杂阻抗成像。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/010

J Jossinet, C Trillaud

{"title":"Imaging the complex impedance in electrical impedance tomography.","authors":"J Jossinet, C Trillaud","doi":"10.1088/0143-0815/13/a/010","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/010","url":null,"abstract":"Measuring the reactive component of the bio-impedance enables a full characterisation of the frequency response of a tissue. The amplitude of the reactive component is relatively small in the frequency range generally used in electrical impedance tomography (EIT). Its measurement is therefore more sensitive to errors. At higher frequencies, the amplitude of this component increases, which increases the signal-to-noise ratio. The stray capacitance, however, also increases and the front-end circuit must be designed carefully. The purpose of the present study is to show the feasibility of the collection of data at relatively high frequencies; 31.25 and 250 kHz were used. Both the real and reactive components were used to reconstruct images from capacitive targets. This study suggests that it may be possible to use multifrequency systems to determine the parameters of frequency loci and therefore tissue characterisation.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"47-50"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754112","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: 17

Electrical impedance tomography. Determination of impedance of tissue in the frequency range 10(-6)-20 MHz: preliminary results. 电阻抗断层扫描。10(-6)-20 MHz频率范围内组织阻抗的测定:初步结果。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/015

J Kozlowska, B Rigaud, E Martinez, M Granie, J P Morucci

引用次数: 2

Electrical impedance tomography using induced and injected currents. 使用感应电流和注入电流的电阻抗断层扫描。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/019

N G Gençer, Y Z Ider, M Kuzuoglu

{"title":"Electrical impedance tomography using induced and injected currents.","authors":"N G Gençer, Y Z Ider, M Kuzuoglu","doi":"10.1088/0143-0815/13/a/019","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/019","url":null,"abstract":"A two-dimensional forward problem formulation is introduced for electrical impedance tomography (EIT) using induced currents. The forward problem is linearised around a certain resistivity distribution and the inverse problem is formulated as a solution of a linear system of equations. Sensitivity of boundary measurements to resistivity variations are analysed for spatially uniform, linear and quadratic fields. The formulation, however, is suitable for studying the effects of a general magnetic field applied to induce the currents in the conductive object. A similar inverse problem formulation is also developed for EIT using injected currents. Simulation studies are performed by reconstructing images of a simulation distribution using both methods separately with generalised inversion. It is also shown that the derived formulations for the inverse problems of the two methods can be combined to solve a larger set of equations with a greater number of independent measurements.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"95-9"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754122","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: 12

Optimal electrolytic chloriding of silver ink electrodes for use in electrical impedance tomography. 用于电阻抗断层扫描的银墨水电极的最佳电解氯化。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/004

E T McAdams, P Henry, J M Anderson, J Jossinet

{"title":"Optimal electrolytic chloriding of silver ink electrodes for use in electrical impedance tomography.","authors":"E T McAdams, P Henry, J M Anderson, J Jossinet","doi":"10.1088/0143-0815/13/a/004","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/004","url":null,"abstract":"The electrode-electrolyte interface impedance may be simplistically modelled by an equivalent circuit comprising a resistance, RTOTAL, in series with an empirical, constant phase angle impedance, ZCPA. This pseudo-capacitance can be thought of as representing empirically the non-faradaic, double layer capacitance in the presence of specific adsorption and surface roughness effects. RTOTAL is the sum of the lead and electrolyte resistances. Depositing a thin layer of silver chloride on silver electrodes can yield improved electrical performance characteristics (potential and impedance) when used in conjunction with a chloride gel. An electrolytically deposited AgCl layer tends to have a rough surface profile thus leading to an increase in the effective interface area. This gives rise to a decrease in RTOTAL and ZCPA, both of which are desirable. Unfortunately AgCl is a relatively poor conductor. Increasing layer thickness causes RTOTAL to increase, thus adversely affecting the inter-electrode impedance at high frequencies. Electrode systems for use in electrical impedance tomography therefore require only relatively thin layers of AgCl.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"19-23"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754204","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: 15

Neural networks for electrical impedance tomography image characterisation. 电阻抗断层成像表征的神经网络。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/023

A S Miller, B H Blott, T K Hames

{"title":"Neural networks for electrical impedance tomography image characterisation.","authors":"A S Miller, B H Blott, T K Hames","doi":"10.1088/0143-0815/13/a/023","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/023","url":null,"abstract":"The Southampton electrical impedance tomography (EIT) system used a Sheffield data acquisition unit and a PC based 'Harlequin' transputer card to reconstruct and display images of the distribution of internal conductivity within the thorax. The system produces real-time images relating to both cardiac and pulmonary function. As a first step towards diagnosis using these images neural nets have been applied to the identification of regions of interest in the EIT images for which some activity with time, such as ventricular ejection, is sought. This paper addresses the use of a back-projection network to identify characteristic regions within the images. The network facilitates the production of automated real-time activity plots by defining their effective extent in the images of specific organs. The application is novel within the medical imaging field as the aim is to use neural networks for real-time image analysis.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"119-23"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754370","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: 12

Noise and spatial resolution of a real-time electrical impedance tomograph. 实时电阻抗层析成像的噪声和空间分辨率。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/024

A M Sinton, B H Brown, D C Barber, F J McArdle, A D Leathard

引用次数: 22

Electrical impedance tomography. Determination of the boundary of an object inserted into a water-filled cylinder. 电阻抗断层扫描。确定插入一个充满水的圆柱体的物体的边界。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/029

Y Z Ider, B Nakiboglu, M Kuzuoglu, N G Gençer

{"title":"Electrical impedance tomography. Determination of the boundary of an object inserted into a water-filled cylinder.","authors":"Y Z Ider, B Nakiboglu, M Kuzuoglu, N G Gençer","doi":"10.1088/0143-0815/13/a/029","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/029","url":null,"abstract":"In order to circumvent the electrode position determination problem in static electrical impedance tomography, it is possible to insert the object to be imaged into a water-filled cylinder on which the electrodes are at fixed and known positions. It has previously been shown that if the boundary of the internally placed object and the conductivity of the salty water in the cylinder are known, then a significant improvement in the conductivity image of the object is obtained. An algorithm for finding the boundary of an internally placed object is developed based on the finite element method (FEM). The boundary is assumed to obey a parametric model and the parameters are estimated by inverting a matrix representing the sensitivity of the boundary voltage measurements to parameter variations. The algorithm assumes that the object's internal conductivity is uniform and known. Simulation studies show that if the internal conductivity is not uniform to the extent found in the arm cross-sections, up to 9% error in the boundary, as measured from a centrally placed reference point, may result. It is also shown that if previous knowledge about the boundary shape is used to model the boundary with fewer numbers of parameters, then the boundary may be found with less error.","PeriodicalId":77070,"journal":{"name":"Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics","volume":"13 Suppl A ","pages":"151-4"},"PeriodicalIF":0.0,"publicationDate":"1992-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/0143-0815/13/a/029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754878","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: 11

Electrical impedance tomography. Technical and experimental problems encountered in impedance spectroscopy in the alpha and beta dispersion regions. 电阻抗断层扫描。在α和β色散区阻抗谱中遇到的技术和实验问题。

Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics Pub Date : 1992-01-01 DOI: 10.1088/0143-0815/13/a/012

J Kozlowska, B Rigaud, E Martinez, V Dubroca, J P Morucci

引用次数: 3