Mimicking relative continuum measurements by electrode data in two-dimensional electrical impedance tomography

This paper introduces a constructive method for approximating relative continuum measurements in two-dimensional electrical impedance tomography based on data originating from either the point electrode model or the complete electrode model. The upper bounds for the corresponding approximation errors explicitly depend on the number (and size) of the employed electrodes as well as on the regularity of the continuum current that is mimicked. In particular, if the input current and the object boundary are infinitely smooth, the discrepancy associated with the point electrode model converges to zero faster than any negative power of the number of electrodes. The results are first proven for the unit disk via trigonometric interpolation and quadrature rules, and they are subsequently extended to more general domains with the help of conformal mappings.

Solusi Semi-Analitik Persamaan Laplace Dengan Syarat Batas Campuran

Solusi dari distribusi potensial dalam bola 3 Dimensi dengan syarat batas campuranberasal dari model fisika didapatkan sebagai sistem persamaan linear tak hingga.Masalah syarat batas campuran ini, berasal dari Tomografi Elektrik yang dikenal sebagai Complete Electrode Model (Model Elektroda Lengkap).

SOLUSI SEMI-ANALITIK PERSAMAAN LAPLACE DENGAN SYARAT BATAS CAMPURAN

Solusi analitik dari distribusi potensial dalam bola 3 Dimensi dengan syarat batas campuran berasal dari model sika didapatkan sebagai sistem persamaan linear tak hingga. Masalah syarat batas campuran ini, berasal dari Tomografi Elektrik yang dikenal sebagai Complete Electrode Model<br />(Model Elektroda Lengkap).

‘Phantom Virtual’ Berbasis Rangkaian Kapasitor untuk Electrical Capacitance Tomography

Pada Electrical Capacitance Tomography (ECT) diperlukan Phantom untuk membangkitkan data yang dapat digunakan untuk menguji algoritma inversi. Boundary data simulator (BDS) didesain dengan menggunakan rangkaian kapasitor. Salah satu elektroda pada boundary dihubungkan dengan sumber tegangan AC (alternating current), sedangkan pada elektroda boundary lainnya akan dilakukan pengukuran arus. Data set arus yang berbeda akan dibangkitkan dengan mengganti variable input dari BDS yaitu nilai kapasitor yang menyusun Phantom. Data yang dihasilkan ini dapat direkonstruksi semisal menggunakan EIDORS (electrical impedance tomography and diffuse optical tomography reconstruction software) yang memfasilitasi Complete Electrode Model (CEM).

Forward and inverse effects of the complete electrode model in neonatal EEG

This paper investigates finite element method-based modeling in the context of neonatal electroencephalography (EEG). In particular, the focus lies on electrode boundary conditions. We compare the complete electrode model (CEM) with the point electrode model (PEM), which is the current standard in EEG. In the CEM, the voltage experienced by an electrode is modeled more realistically as the integral average of the potential distribution over its contact surface, whereas the PEM relies on a point value. Consequently, the CEM takes into account the subelectrode shunting currents, which are absent in the PEM. In this study, we aim to find out how the electrode voltage predicted by these two models differ, if standard size electrodes are attached to a head of a neonate. Additionally, we study voltages and voltage variation on electrode surfaces with two source locations: 1) next to the C6 electrode and 2) directly under the Fz electrode and the frontal fontanel. A realistic model of a neonatal head, including a skull with fontanels and sutures, is used. Based on the results, the forward simulation differences between CEM and PEM are in general small, but significant outliers can occur in the vicinity of the electrodes. The CEM can be considered as an integral part of the outer head model. The outcome of this study helps understanding volume conduction of neonatal EEG, since it enlightens the role of advanced skull and electrode modeling in forward and inverse computations. NEW & NOTEWORTHY The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary.