Application of fluxgate gradiometer in magnetopneumography

Tomek, Jiří; Platil, Antonin; Ripka, Pavel; Kašpar, Petr

doi:10.1016/j.sna.2006.02.033

Cited by 11 publications

(15 citation statements)

References 9 publications

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“…The basic procedures of our MPG measurements were already described, e.g., in [10] and [11]. Subjects or phantoms that are to be examined must be magnetized in a strong DC field prior to scanning in order to have properly aligned magnetizations.…”

Section: The Measurement Equipmentmentioning

confidence: 99%

“…The measured magnetic field data can be used to determine the dust load in lungs [2]- [12] and also eventually its distribution, for which we have used artificial neural networks with partial success [10], [11]. However, the field variations during the step-by-step scans (several minutes for all the nodes) bias the field-maps considerably.…”

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confidence: 99%

“…This mode is more susceptible to a background field gradient variation, which can be tens of nT in a short time between the measurement points. Some authors use methods of tracking the background by a separate reference gradiometer [16], [25] in order to subtract it from the useful signal, but our study with fluxgates has shown that this approach has serious limitations in the real environment of an ordinary laboratory [11]. This finally motivated us to experiment with solutions that enable a combination of our two basic needs: a) evaluating more data acquired in several layers above the tested object and b) the possibility to determine and suppress the background field variations.…”

mentioning

confidence: 99%

“…We have used single "FoGs" in all previous research [2]- [5], [10], [11], [26], [27]. The former setup allowed satisfactory estimates of the total dust load [12] and made the determination of the simple compact artificial sources possible [5], [10], [11].…”

mentioning

confidence: 99%

“…The former setup allowed satisfactory estimates of the total dust load [12] and made the determination of the simple compact artificial sources possible [5], [10], [11]. Using such a setup, the time variations of the background gradient during scanning could not be recorded and suppressed.…”

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confidence: 99%

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Multiple Layer Scanning in Magnetopneumography

2009

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Abstract-In magnetopneumography (MPG), we scan weak remanent magnetic fields (in the range of nT) of ferromagnetic dust deposited in the lungs of affected workers. This is carried out in an unshielded lab. Variations of the background field during the scanning period bias the inversion process, i.e., the estimation of the magnetic sources from the measured field. We present an innovative mathematical technique of finding a field equation uniquely describing the magnetic moments in the nodes of the measurement space. Simultaneously, it enables the tracking of the values of the disturbing gradient created by external distant sources during the time of scanning. Our method preserves the first-order gradients obtained in multiple layers (scan heights above the object) instead of losing data with the higher order gradients which are not effective here. Six coaxially aligned fluxgates were used for scanning the field maps. The obtained five first-order gradients for each node give us the parameters of the respective "equivalent" magnetic sources. Furthermore, we obtain a parameter describing the error originating mainly from the background field. The main limits of the presented method are: 1) the alignment of the probes; 2) their number being limited by a minimum distance; and 3) nonhomogeneity of the external field.Index Terms-Computational elimination of disturbances, magnetopneumography, multiple layer scanning.

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Multiple Layer Scanning in Magnetopneumography

2009

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3D Magnetopneumography Magnetic Dipole Model and Its Application Using Fluxgate Gradiometers

Fang

2019

Bioelectromagnetics

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Magnetopneumography (MPG) as a non‐invasive method for pneumoconiosis diagnosis has been developed to evaluate the load and spatial distribution of particles within the human lungs through scanning of remanent magnetic fields after magnetization of the subject in a strong direct current field. The measurement of particle spatial distribution is very important for pneumoconiosis diagnosis because localized deposits may be associated with some pathological changes such as pulmonary fibrosis. Previous research found that loads of magnetite particles were proportional to their magnetic dipole moments. The three‐dimensional (3D) MPG magnetic dipole model (MDM) proposed in this paper and based on Biot–Savart Law and matrix manipulation provides a means of precise measurement of the particle distribution and load amount. A styrofoam + magnetite powder phantom with magnetization was laid on a nonmagnetic board. Two first‐order fluxgate gradiometers with 10–12 T sensitivity were coaxially applied over and under the phantom and used for scanning remanent magnetic fields. This paper provides validation results using 3D MPG MDM through two experiments. The overall error of the simulation results is 0.2–2.7% in the center and 7.28–9.42% in the corners of the subject. Finally, this paper gives clinical experiments with a welder suffering stage‐II pneumoconiosis and states that the 3D MPG MDM shows similar results to X‐ray chest films in pneumoconiosis diagnosis. The results suggest that the 3D MPG MDM is potentially a reasonable and accurate algorithmic model to inversely track the load amount and distribution of magnetite particles within the lungs. Bioelectromagnetics. 2019;40:472–487. © 2019 Wiley Periodicals, Inc

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Parallel Fluxgate Magnetometers

Janošek

2016

Smart Sensors, Measurement and Instrumentation

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Application of fluxgate gradiometer in magnetopneumography

Cited by 11 publications

References 9 publications

Multiple Layer Scanning in Magnetopneumography

Multiple Layer Scanning in Magnetopneumography

3D Magnetopneumography Magnetic Dipole Model and Its Application Using Fluxgate Gradiometers

Parallel Fluxgate Magnetometers

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