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Dive into the research topics where Cesar Marco Antonio Robles Gonzalez is active.

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Featured researches published by Cesar Marco Antonio Robles Gonzalez.


PLOS ONE | 2013

Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

Cesar Marco Antonio Robles Gonzalez; José Valencia; Alfredo Mora; Fernando Herrerı́as González; Beatriz Velasco; Martin A. Porras; Javier Salgado; Salvador M. Polo; Nidiyare Hevia-Montiel; Sergio Cordero; Boris Rubinsky

Motivated by the need of poor and rural Mexico, where the population has limited access to advanced medical technology and services, we have developed a new paradigm for medical diagnostic based on the technology of “Volumetric Electromagnetic Phase Shift Spectroscopy” (VEPS), as an inexpensive partial substitute to medical imaging. VEPS, can detect changes in tissue properties inside the body through non-contact, multi-frequency electromagnetic measurements from the exterior of the body, and thereby provide rapid and inexpensive diagnostics in a way that is amenable for use in economically disadvantaged parts of the world. We describe the technology and report results from a limited pilot study with 46 healthy volunteers and eight patients with CT radiology confirmed brain edema and brain hematoma. Data analysis with a non-parametric statistical Mann-Whitney U test, shows that in the frequency range of from 26 MHz to 39 MHz, VEPS can distinguish non-invasively and without contact, with a statistical significance of p<0.05, between healthy subjects and those with a medical conditions in the brain. In the frequency range of between 153 MHz to 166 MHz it can distinguish with a statistical significance of p<0.05 between subjects with brain edema and those with a hematoma in the brain. A classifier build from measurements in these two frequency ranges can provide instantaneous diagnostic of the medical condition of the brain of a patient, from a single set of measurements. While this is a small-scale pilot study, it illustrates the potential of VEPS to change the paradigm of medical diagnostic of brain injury through a VEPS classifier-based technology. Obviously substantially larger-scale studies are needed to verify and expand on the findings in this small pilot study.


Physiological Measurement | 2008

The effect of brain hematoma location on volumetric inductive phase shift spectroscopy of the brain with circular and magnetron sensor coils: a numerical simulation study

R. Rojas; Boris Rubinsky; Cesar Marco Antonio Robles Gonzalez

This numerical simulation study addressed the effects of the location of a discrete brain hematoma on the volumetric inductive phase shift of the brain measured with an induction circular sensor coil and an induction magnetron sensor coil. The theoretical study simulates the brain cavity as a circular sphere transversely centered with respect to the circular and magnetron sensor coils. As a case study for the effects of hematoma location, we employed similar size simulated spherical hematomas placed at three different positions from the center of the brain outward. A three-dimensional finite element analysis of the field equations in the frequency range from 100 kHz to 100 MHz revealed a substantial effect of hematoma location on the ability of both the circular and magnetron sensors to detect the hematomas. In particular it was found that there are frequencies, which may be related to resonance, at which the occurrence of the hematomas has no effect on the volumetric inductive phase shift of the brain. Furthermore it was found that the relative sensitivity of circular and magnetron sensor coils with respect to the occurrence of hematoma varies with the location of the hematoma.


Physiological Measurement | 2009

The detection of brain ischaemia in rats by inductive phase shift spectroscopy.

Cesar Marco Antonio Robles Gonzalez; Cleva Villanueva; C Vera; O Flores; R D Reyes; Boris Rubinsky

Ischaemia in the brain is an important clinical problem that is often monitored and studied with expensive devices such as MRI and PET, which are not readily available in low economical resource parts of the world. We have developed a new less expensive tool for non-invasive monitoring of ischaemia in the brain. This is a first feasibility study describing the concept. The system is based on the hypothesis that electromagnetic properties of the tissue change during ischaemia and that measuring the electromagnetic properties of the bulk of the brain with non-contact means can detect these changes. The apparatus we have built and whose design we describe here consists of two electromagnetic coils placed around the head. The system measures the bulk change in time of the phase difference between the electromagnetic signal on the two coils in a range of frequencies. A mathematical model simulating the device and the measurement is also introduced. Ischaemia was induced in the brain of rats by occlusion of the right cerebral and carotid arteries. Experimental subjects were monitored for 24 h. Inductive phase shift measurements were made at five frequencies in the range of 0.1-50 MHz eight times during the observation period. An ex vivo estimation of the percentage of necrosis in the ischemic subjects at t = 24 h was done. The mathematical model was also applied to the experimental tested situation. The results of both experiments and theory show significant phase shifts increase as a function of frequency and ischaemia time. The theoretical and experimental results suggest that the tested technique has the potential to detect the processes and level of ischaemia in the brain by non-invasive, continuous, bulk volumetric monitoring with a simple and inexpensive apparatus.


Journal of Physics: Conference Series | 2010

Over-hydration detection in brain by magnetic induction spectroscopy

Cesar Marco Antonio Robles Gonzalez; María Pérez; Nidiyare Hevia; Fernándo Arámbula; Omar Flores; Eliot Aguilar; Ivonne Hinojosa; Leo Joskowicz; Boris Rubinsky

Detection and continuous monitoring of edema in the brain in early stages is useful for assessment of medical condition and treatment. We have proposed a solution in which the bulk measurements of the tissue electrical properties to detect edema or in general accumulation of fluids are made through measurement of the magnetic induction phase shift between applied and measured currents at different frequencies (Magnetic Induction Spectroscopy; MIS). Magnetic Resonant Imaging (MRI) has been characterized because its capability to detect different levels of brain tissue hydration by differences in diffusion- weighted (DW) sequences and its involve apparent diffusion coefficient (ADC). The objective of this study was to explore the viability to use measurements of the bulk tissue electrical properties to detect edema or in general accumulation of fluids by MIS. We have induced a transitory and generalized tissue over-hydration condition in ten volunteers ingesting 1.5 to 2 liters of water in ten minutes. Basal and over-hydration conditions were monitored by MIS and MRI. Changes in the inductive phase shift at certain frequencies were consistent with changes in the brain tissue hydration level observed by DW-ADC. The results suggest that MIS has the potential to detect pathologies associated to changes in the content of fluids in brain tissue such as edema and hematomas.


Journal of Physics: Conference Series | 2013

Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue

Cesar Marco Antonio Robles Gonzalez; Lucila M. Lozano; M C Uscanga; J. G. Silva; Salvador M. Polo

Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.


Journal of Applied Mathematics | 2013

First Characterization of a New Method for Numerically Solving the Dirichlet Problem of the Two-Dimensional Electrical Impedance Equation

Marco Ramirez-Tachiquin; Cesar Marco Antonio Robles Gonzalez; Rogelio Adrian Hernandez-Becerril; Ariana Guadalupe Bucio Ramirez

Based upon the elements of the modern pseudoanalytic function theory, we analyze a new method for numerically solving the forward Dirichlet boundary value problem corresponding to the two-dimensional electrical impedance equation. The analysis is performed by introducing interpolating piecewise separable-variables conductivity functions in the unit circle. To warrant the effectiveness of the posed method, we consider several examples of conductivity functions, whose boundary conditions are exact solutions of the electrical impedance equation, performing a brief comparison with the finite element method. Finally, we discuss the possible contributions of these results to the field of the electrical impedance tomography.


Archive | 2007

Circular and Magnetron Inductor/Sensor Coils to Detect Volumetric Brain Edema by Inductive Phase Shift

Cesar Marco Antonio Robles Gonzalez; R. Rojas; Boris Rubinsky

Circular and planar magnetron coils were evaluated and compared for their ability to detect edema in the brain through volumetric inductive phase shift spectroscopy. The circular coil was considered as a single turn wire and the magnetron surface coil configuration was based on the principle of the cavity magnetron with successive slots. The brain cavity was modeled as an idealized sphere transversely centered with respect to the coils. The volumetric sensitivity to changes in the brain was examined by inserting in the brain cavity a spherical hematoma. The magnetic flux densities generated by the inductor and magnetron coils were evaluated through a three-dimensional finite elements solution of the quasi-static equations. Spectra of inductive phase shift induced in a second circular or magnetron receiver coils were estimated in a range of frequencies from 100KHz to 50MHz. In the analyzed range, the sensitivity of the phase shift to the presence of the edema increased with frequency. Using a planar magnetron as an induction coil increased somewhat the sensitivity to volumetric phase shift detection of edema over the use of a circular coil.


Archive | 2014

On the Numerical Solutions of Boundary Value Problems in the Plane for the Electrical Impedance Equation: A Pseudoanalytic Approach for Non-Smooth Domains

Cesar Marco Antonio Robles Gonzalez; Ariana Guadalupe Bucio Ramirez; Marco Pedro Ramirez Tachiquin; Victor Daniel Sanchez Nava

We study the Electrical Impedance Equation within a special class of domains, whose boundaries posses non-smooth points. The forward Dirichlet boundary value problem is solved bias a novel numerical method, based upon the Pseudoanalytic Function Theory, that does not require additional regularization techniques to fulfill the boundary condition at the non-smooth points.


Mathematical Problems in Engineering | 2014

A Regularization Process for Electrical Impedance Equation Employing Pseudoanalytic Function Theory

Cesar Marco Antonio Robles Gonzalez; Ariana Guadalupe Bucio Ramirez; Volodymyr Ponomaryov; Marco Pedro Ramirez Tachiquin

The electrical impedance equation is considered an ill-posed problem where the solution to the forward problem is more easy to achieve than the inverse problem. This work tries to improve convergence in the forward problem method, where the Pseudoanalytic Function Theory by means of the Taylor series in formal powers is used, incorporating a regularization method to make a solution more stable and to obtain better convergence. In addition, we include a comparison between the designed algorithms that perform proposed method with and without a regularization process and the autoadjustment parameter for this regularization process.


Archive | 2019

Innovative Biosensor of Circulating Breast Cancer Cells; a Potential Tool in Latin America Oncology Rooms

Cesar Marco Antonio Robles Gonzalez; Herberth Bravo

The detection of circulating tumoral cells represents the possibility for therapy monitoring as well as prevent metastasis in oncology patients. Portable and economical technologies are required in most of the oncology rooms of third level Latin America hospitals. In this work an innovative biosensor of circulating breast cancer cells on the basis of bioimpedance spectroscopy measurements assisted with magnetic nanoparticles is presented. The technical proposal involves a microfluidic system for cancer cells separation by immunomagnetic technique and its detection by multifrequency bioimpedance measurements. An experimental proof of concept to detect a typical breast cancer cell line was developed to evaluate the sensitivity of the system. The results shown the technical proposal feasibility as portable, inexpensive and non-invasive biosensor of circulating tumoral cells, as well as its technical feasibility for implementation in oncology rooms of Latin America third level hospitals.

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Dive into the Cesar Marco Antonio Robles Gonzalez's collaboration.

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Boris Rubinsky

University of California

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Cleva Villanueva

Instituto Politécnico Nacional

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R. Rojas

Universidad Autónoma Metropolitana

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Jose L. Tapia

Pontifical Catholic University of Chile

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Alan R Quiróz

Universidad del Valle de México

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C Vera

Instituto Politécnico Nacional

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Eliot Aguilar

Instituto Politécnico Nacional

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Fernándo Arámbula

National Autonomous University of Mexico

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