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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

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Multifrequency electrical impedance tomography. 多频电阻抗断层扫描。
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/014
P M Record, R Gadd, F Vinther
{"title":"Multifrequency electrical impedance tomography.","authors":"P M Record,&nbsp;R Gadd,&nbsp;F Vinther","doi":"10.1088/0143-0815/13/a/014","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/014","url":null,"abstract":"<p><p>Multifrequency tomography may be conveniently achieved by sequentially sweeping the probing drive current and measuring the resultant voltages at each frequency. If events change during measurement comparisons between frequencies cannot be made. Mixing several frequency components may decrease acquisition time but increase the complexity of the instrumentation. A third method is described using Fourier transformation that enables simultaneous multifrequency measurements without an increase in instrumentation. A signal is constructed from a number of sinusoidal components of known amplitude and phase. This group of components is transformed into a time series by the inverse Fourier transform and applied to the object via a voltage or current source. Transforming the detected voltage back into Fourier components will provide the frequency response of the object. Data are collected in this way for all projections and tomograms reconstructed for each frequency. This has the advantage that no special detector is required; both in-phase and quadrature components are available and systematic errors may be easily corrected by software. This technique is demonstrated using a resistor phantom with known frequency-dependent perturbations.</p>","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":"67-72"},"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/014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754117","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: 23
Measurement of pharyngeal transit time by electrical impedance tomography. 电阻抗断层扫描法测量咽传输时间。
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/038
P Liu, H Griffiths, C M Wiles, K M Nathadwarawala, W Stewart
{"title":"Measurement of pharyngeal transit time by electrical impedance tomography.","authors":"P Liu,&nbsp;H Griffiths,&nbsp;C M Wiles,&nbsp;K M Nathadwarawala,&nbsp;W Stewart","doi":"10.1088/0143-0815/13/a/038","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/038","url":null,"abstract":"<p><p>The feasibility of using electrical impedance tomography (EIT) for measuring pharyngeal transit time has been investigated. Imaging sequences were obtained on the neck in a group of eight healthy subjects when swallowing solutions of different electrical conductivities. The solutions used were aqueous Dioralyte (1.5 S m-1) and tap water (0.04 S m-1). The effects of movement upon the images were large compared with the changes due to the solutions, but these were cancelled by a subtraction technique. The mean value of the EIT pharyngeal transit time parameter was 370 +/- 120 ms. EIT has the advantage that repeated measurements could be performed without fear of hazard in contrast to the established technique of video fluoroscopy which involves ionising</p>","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":"197-200"},"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/038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754206","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: 16
Raw data interchange format for electrical impedance tomography. 电阻抗层析成像的原始数据交换格式。
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/039
P M Record, P J Riu Costa
{"title":"Raw data interchange format for electrical impedance tomography.","authors":"P M Record,&nbsp;P J Riu Costa","doi":"10.1088/0143-0815/13/a/039","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/039","url":null,"abstract":"<p><p>A data interchange format is described to allow groups working on electrical impedance tomography (EIT) with disparate algorithms and instruments to compare results. The procedure has been tested by exchanging data by e-mail. The format is defined in the appendix.</p>","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":"201-7"},"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/039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754207","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: 1
Electrical impedance tomography. Improved wideband, high CMRR (common mode rejection ratio) instrumentation amplifier. 电阻抗断层扫描。改进的宽带，高CMRR(共模抑制比)仪表放大器。
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/011
Q S Zhu, F J Lidgey, M A Vere Hunt
{"title":"Electrical impedance tomography. Improved wideband, high CMRR (common mode rejection ratio) instrumentation amplifier.","authors":"Q S Zhu,&nbsp;F J Lidgey,&nbsp;M A Vere Hunt","doi":"10.1088/0143-0815/13/a/011","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/011","url":null,"abstract":"<p><p>A wideband high CMRR instrumentation amplifier is described. Based on a previously reported current-mode design, the improved amplifier features excellent CMRR performance of better than 60 dB up to 200 kHz with unity differential gain.</p>","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":"51-5"},"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/011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754114","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: 14
The performance of integrated transconductance amplifiers as variable current sources for bio-electric impedance measurements. 集成跨导放大器作为可变电流源用于生物电阻抗测量的性能。
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/005
D N Smith
{"title":"The performance of integrated transconductance amplifiers as variable current sources for bio-electric impedance measurements.","authors":"D N Smith","doi":"10.1088/0143-0815/13/a/005","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/005","url":null,"abstract":"<p><p>Multiple applied current impedance measurement systems require numbers of current sources which operate simultaneously at the same frequency and within the same phase but at variable amplitudes. Investigations into the performance of some integrated operational transconductance amplifiers as variable current sources are described. Measurements of breakthrough, non-linearity and common-mode output levels for LM13600, NE5517 and CA3280 were carried out. The effects of such errors on the overall performance and stability of multiple current systems when driving floating loads are considered.</p>","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":"25-30"},"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/005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754208","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: 3
Conductivity interface modelling with dipoles by means of optimal control and boundary element methods in impedance tomography. 阻抗层析中基于最优控制和边界元方法的偶极子电导率界面建模。
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/021
P M Marsili, G Mounié, M Granié, J P Morucci
{"title":"Conductivity interface modelling with dipoles by means of optimal control and boundary element methods in impedance tomography.","authors":"P M Marsili,&nbsp;G Mounié,&nbsp;M Granié,&nbsp;J P Morucci","doi":"10.1088/0143-0815/13/a/021","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/021","url":null,"abstract":"<p><p>Optimal control techniques have been combined with Alessandrini's singular perturbation method and Wexler's algorithm to reconstruct images in impedance imaging. We have also considered an integral formulation of the potential problem, which has led us to introduce an array of dipoles whose position, orientation and length can be optimised to model the conductivity discontinuities.</p>","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":"107-11"},"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/021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754367","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: 1
The modulation transfer function in impedance imaging. 阻抗成像中的调制传递函数。
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/031
J P Morucci, Y Shi, B Rigaud
{"title":"The modulation transfer function in impedance imaging.","authors":"J P Morucci,&nbsp;Y Shi,&nbsp;B Rigaud","doi":"10.1088/0143-0815/13/a/031","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/031","url":null,"abstract":"<p><p>The concepts of the point spread function (PSF) and its Fourier transform, the modulation transfer function (MTF) are introduced to evaluate an impedance imaging system. The effects of some practical factors which should be taken into account in calculating the MTF are analysed. Experimental results from the groups in Sheffield, Barcelona and Toulouse are presented.</p>","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":"161-6"},"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/031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754880","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: 1
Application of electrical impedance tomography to the determination of lung volume. 电阻抗断层扫描在肺容积测定中的应用。
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/032
L A Smulders, A van Oosterom
{"title":"Application of electrical impedance tomography to the determination of lung volume.","authors":"L A Smulders,&nbsp;A van Oosterom","doi":"10.1088/0143-0815/13/a/032","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/032","url":null,"abstract":"<p><p>Trans-thoracical electrical impedance measurements on a human subject have been performed using the Sheffield equipment. These measured transfer impedances are compared with computed ones, based on an inhomogeneous, torso-shaped volume conductor, for different values of the overall electrical conductivities sigma l and sigma r of left and right lung. Each measured set of impedances is compared with all calculated sets. The remaining (minimum) residual difference epsilon is used as a measure of the goodness of fit, and the values of sigma l and sigma r for which epsilon is minimal are taken as representing the overall conductivities of the lungs. For data measured at various stages within the respiratory cycle, sigma l and sigma r have been determined. The results are found to relate well to physiology: for a measurement taken at maximum expiration sigma l and sigma r indicate almost homogeneity, whereas for end inspiratory level sigma l and sigma r tend towards values of 0.2, which is a realistic value for the relative conductivity of lung tissue.</p>","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":"167-70"},"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/032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754881","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: 0
Back-projection distortions in applied potential tomography images due to non-uniform reference conductivity distributions. 由于参考电导率分布不均匀，应用电位断层成像中的反向投影失真。
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/022
N J Avis, D C Barber, B H Brown, M A Kiber
{"title":"Back-projection distortions in applied potential tomography images due to non-uniform reference conductivity distributions.","authors":"N J Avis,&nbsp;D C Barber,&nbsp;B H Brown,&nbsp;M A Kiber","doi":"10.1088/0143-0815/13/a/022","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/022","url":null,"abstract":"<p><p>An investigation was conducted to determine and quantify the distortions in applied potential tomography (APT) images reconstructed from data originating from bodies of non-uniform reference conductivity distributions. The results show that the distortions in the images are dependent on the reference conductivity distribution and on whether the images are formed by back projection along the assumed equipotentials of a uniform reference conductivity distribution or along the equipotentials of the true conductivity distribution. We believe that this last finding is significant since our previously held expectation, similar to that of Yorkey and Webster (1987), that back projection along the true equipotentials of the reference conductivity distribution should result in an accurate reconstruction, is shown to be incorrect.</p>","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":"113-7"},"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/022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754369","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
Imaging the complex impedance of the thorax. 胸腔复杂阻抗成像。
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/016
H Griffiths, H T Leung, R J Williams
{"title":"Imaging the complex impedance of the thorax.","authors":"H Griffiths,&nbsp;H T Leung,&nbsp;R J Williams","doi":"10.1088/0143-0815/13/a/016","DOIUrl":"https://doi.org/10.1088/0143-0815/13/a/016","url":null,"abstract":"<p><p>Respiration-related changes in the complex impedance were obtained on the thorax in three volunteers. The real part of the image clearly showed the lungs as regions of increased conductivity on expiration. The imaginary part of the image, reflecting changes in the ratio of permittivity to conductivity, showed a central negative region surrounded by a positive region extending to the periphery of the lungs. These features may be due to movement of the diaphragm and liver within the sensitive volume during respiration.</p>","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":"77-81"},"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/016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12754119","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: 33
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