CN100381096C - Non-contact magnetic inductive encephaledema monitoring method - Google Patents
Non-contact magnetic inductive encephaledema monitoring method Download PDFInfo
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Abstract
The present invention discloses a non-contact magnetic induction hydrocephalus monitoring method, which uses methods of magnetic induction information detection and magnetic induction imaging for monitoring all hydrocephalus by utilizing the principle of eddy current detection. A monitored target (skull) is laid in an excitation magnetic field, the disturbed magnetic field of eddy current is induced by utilizing the monitored target, and the variation of the magnetic field is detected. Electric conductivity in the target and the distribution of the variation of the electric conductivity can be obtained, so that the developing process of hydrocephalus can be monitored. The detected variation information of the magnetic field can be utilized to analyze various kinds of information, can reconstruct images, and reflects the distribution of electric conductivity in the monitored target (skull) and the variation thereof (pathological changes of hydrocephalus). The non-contact monitoring method of the present invention has the advantages of no contact and no electricity leakage, and also has the advantages that corresponding medical instruments can be developed according to the method, corresponding information, curves, images and numerical values can be displayed, and various hydrocephalus patients can be continuously monitored.
Description
Technical field
The invention belongs to medical imaging and monitoring method in the biomedical engineering field, specifically refer in particular to non-contact magnetic inductive mode (one-dimension information and imaging) monitoring cerebral edema.
Technical background
Utilize imaging means such as X-CT, MRI to carry out imaging at present to the cerebral edema that cerebral hemorrhage, ischemia cause, but because the radioactivity of X-CT is difficult for repeatedly using, and X-CT, MRI belong to main equipment, can't use continuously in that bed is other, to the evolution of cerebral edema can't be continuously, monitor in real time.
The data-searching of carrying out according to the applicant, the technology approaching with the application is the patent " method of non-invasive clinical monitoring intracranial edema " of Bo'en Sci. ﹠ Tech. Co., Ltd., Chongqing's application in 2002, this method is to utilize subtend stickup electrode on head, to the inner low-frequency current that injects of head, at the inner current field that forms of volume conductor, when the organizational structure of electric current field domain changed, the current field redistribution was carried out non-invasive monitoring by phase-detection by computer and display screen.
Contactless noinvasive triage is surveyed and monitoring is the new method of medical domain.Mode about the mapping magnetic induction image is the method that does not all have the new magnetic induction detection of report at present both at home and abroad.Therefore study that a kind of to be used for the other method of in real time cerebral edema being monitored of bed significant.
Summary of the invention
At the deficiency of existing technology and method and clinical needs, the objective of the invention is to, proposing a kind of is the noncontact cerebral edema magnetic induction monitoring method of the cerebral edema of various craniocerebral injuries initiations, this method can be used for the detection and the monitoring of the cerebral edema of general apoplexy and closed injury initiation, can also be used for the detection and the monitoring, the particularly detection of head war wound and monitoring of the cerebral edema of open injury initiation.
To achieve these goals, the present invention takes following technical solution:
The non-contact magnetic inductive encephaledema monitoring method is utilized the EDDY CURRENT principle, magnetic induction information is detected and the method for magnetic induction image is used for the monitoring of various cerebral edemas, comprises the following steps:
1) excitation coil and measurement coil are seated near around the monitoring objective (human body head), the alternating magnetic field that is produced by excitation coil is as excitation field B0, this magnetic field produces eddy current because of the electromagnetic induction effect makes it during by monitoring objective, this eddy current produces induced field Δ B simultaneously and changes the power of former excitation field, is measuring detection induced field Δ B on the coil; When the monitoring objective impedance changes, promptly influence the intensity and the distribution of eddy current, and then make the voltage of magnetic test coil and induction reactance also change;
2) the magnetic field Δ B that records by magnetic test coil, the distribution of impedance that can reflect conductor, and according to the distribution of impedance information that is consecutively detected, extract corresponding variation numerical value, curve, and according to measurement data reconstruct (so-called reconstruct is meant the inverse problem of finding the solution partial differential equation, can be referring to " counting method of partial differential equation inverse problem and application thereof ", Su Chaowei work, publishing house of Northwestern Polytechnical University, nineteen ninety-five) image or topography;
3) with different excitation coils and measurement coil arrangement mode;
Its arrangement mode is respectively:
1. the excitation coil that quantity is equal to measure coil and link to each other successively and be arranged in the circle shape round monitoring objective, target is carried out fault imaging, with the position and the variation tendency of the conductivity variations of the aspect that reflects target internal coil correspondence;
2. excitation coil that quantity is equal to and measurement coil arrangement are arranged on the one or both sides of monitoring objective, monitoring objective is carried out the monitoring of magnetic induction one-dimension information, mobile successively excitation coil and measurement coil, relatively the result of each time measurement is with the projected position and the variation tendency of reflection target internal conductivity variations;
3. the excitation coil that quantity is equal to and measure the coil forming array, be placed on the monitoring objective both sides, one side is the excitation coil array, opposite side is the slotted line coil array, in the excitation coil array, apply synchronous alternating current, then the place forms proximate parallel magnetic field in the middle of coil array, is mapped to picture, obtains the electrical conductivity general status and the variation tendency of monitoring objective inside.
Method major advantage of the present invention is noncontact, no wound, need not to paste any electrode at human body head, corresponding Medical Instruments can be developed according to this method, corresponding information, curve, image, numerical value can be shown, can be to various cerebral edema patient's continuous monitorings.
Description of drawings
Fig. 1 is a theory diagram of the present invention;
Fig. 2 is a fault imaging excitation metering system of the invention process;
Fig. 3 is the excitation metering system that one-dimension information of the invention process detects; Wherein a is that the offside excitation is measured, and b is that the homonymy excitation is measured;
Fig. 4 is the picture excitation metering system that is mapped to of the invention process;
Fig. 5 field domain sensitivity; Wherein a is the relation of target along Y-axis deviation post and output phase shift, and b is the relation of target along Y-axis deviation post and output phase shift;
Fig. 6～Fig. 8 is the circuit diagram of a kind of embodiment of the present invention.
The present invention is described in further detail with enforcement below in conjunction with accompanying drawing.
The specific embodiment
Non-contact magnetic inductive encephaledema monitoring method of the present invention is to utilize near the excitation coil monitoring objective (head) to produce magnetic field, target (head) places excitation field, utilize target (head) induced inside to go out the disturbed magnetic field of eddy current, measure the variation in coil detection magnetic field, show by relevant detection circuit and computer, various cerebral edemas (open injury, closed injury, apoplexy) are carried out the noncontact monitoring, and concrete grammar is:
1. fault imaging:
Adopt a plurality of excitations, slotted line corral to be arranged in circle shape (excitation, measurement coil are respectively 6,8,10,12,14,16,32, according to the practical situation adjustment, see Fig. 2) around target (head).
Its operation principle is, in some coils, apply alternating current (as excitation), will produce alternating magnetic field, this magnetic field arrives other all coils (as measuring) through spatial transmission, the propagation in magnetic field is subjected to the influence of the spatial telegram in reply conductance of passing through, compare and measure the phase contrast of coil and excitation coil, just can obtain the information of space telegram in reply conductance; Change excitation coil successively, and measure respectively, can obtain one group of complete data at other coils; According to restructing algorithm, can rebuild the distributed image of two dimension or three-dimension disclocation internal conductance rate or its variable quantity.In the measuring process, excitation and measurement coil do not need to move.
2. magnetic induction one-dimension information monitoring:
1) excitation is measured respectively in monitoring objective (head) both sides, referring to Fig. 3:
The quantity of excitation coil and measurement coil is respectively 2 or 4 or 6 or 8, wherein if use 2, then selects 1 excitation coil, 1 measurement coil (Fig. 3 a's is a kind of).
Excitation coil and measure coil and keep coaxial state and distance constant.Some positions at head apply alternating current by excitation coil, produce alternating magnetic field, are measuring the magnetic signal that the coil measurement induces then; Mobile excitation coil and measure coil encourages once more and measures; Relatively the result of twice measurement if bigger difference is arranged, illustrates that then the intermediary distribution of conductivity of twice measurement is inconsistent.At continuous mobile excitation coil of whole head and measurement coil, just can obtain whole distribution of conductivity state.
Because excitation coil and measure the coil offside and distribute, the distribution of conductivity state that this kind method can better detection head center position.
2) excitation is measured at target (head) homonymy:
Excitation slotted line number of turns amount is identical: quantity is respectively 2, and (1 as excitation, 1 as measuring), 4 (2 as excitation, 2 as measuring), 6 (3 are used as excitation, and 3 as measuring), 8 (4 as excitation, 4 as measuring), wherein if use 2, then select 1 excitation coil, 1 measurement coil (Fig. 3 b's is a kind of).
Excitation coil remains on same plane with the measurement coil and distance is constant.Some positions at head apply alternating current by excitation coil, produce alternating magnetic field, are measuring the magnetic signal that the coil measurement induces then; Mobile excitation coil and measure coil encourages once more and measures; Relatively the result of twice measurement if bigger difference is arranged, illustrates that then the intermediary distribution of conductivity of twice measurement is inconsistent.At continuous mobile excitation coil of whole head and measurement coil, just can obtain whole distribution of conductivity state.
Because excitation coil and measure the coil homonymy and distribute, the distribution of conductivity state that this kind method can better detection head edge position.
3. be mapped to picture: the excitation coil that quantity is equal to and measure the coil forming array, be placed on monitoring objective (head) both sides, a side is the excitation coil array, and opposite side is the slotted line coil array, and its array is 2 * 2,3 * 3,4 * 4,5 * 5 or the like, sees Fig. 4.
The excitation coil array is coaxial with parallel distribution of excitation coil array and centre.In the excitation coil array, apply synchronous alternating current, then can in the middle of coil array, form proximate parallel magnetic field in the place.This method can improve the magnetic induction in magnetic field effectively, and is difficult for dispersing, and is convenient to outside certain distance (penetration head) and measures.Measure at the measurement coil position, can directly form the map image of the spatial electrical conductivity of passing through; Can also rotate whole excitation coil array and slotted line coil array, thereby form the distribution of conductivity image of two dimension or three-dimension disclocation.
Realize the inventive method a kind of mode---the system block diagram of fault imaging mode as shown in Figure 1.Coil comprises 8,16 or 32 groups, and each group is made of two coils, and one is used for excitation, and another is used for measuring.All coils is rounded around monitoring objective (head).Each excitation coil to a certain group drives, and pumping signal is produced by driving source, amplifies by power amplifier, behind impedance matching, is connected on the specified excitation coil by permutator again.Once after the excitation, detect response signal on the measurement coil of other all coil groups, the selection of coil groups is switched successively by permutator, an end of input phase discriminator after impedance matching and amplification; In addition, also detect its response signal,, receive the other end of phase discriminator as the synchronous reference signal of driving source with excitation coil measurement coil on the same group.Exportable two phase of input signals of phase discriminator are poor.This phase signal is by AD analog digital conversion input computer.After in computer, carrying out necessary processing, use restructing algorithm and can rebuild the interior distribution of conductivity image of coil place tomography.
Fig. 5 be excitation coil and measure coil over against the time, different electrical conductivity objects respectively vertically with the horizontal change curve of measuring the phase contrast of gained when mobile.Can find out that all electrical conductivity is big more from figure a and figure b, the phase contrast of measuring gained is also big more.
The circuit diagram that it is above-mentioned such as Fig. 6 are to shown in Figure 8, and HC14DY is the active crystal oscillator of 160MHz among Fig. 6, is used to produce the square wave clock signal; AD9850 is a Direct Digital signal synthesis chip, is used to produce pumping signal and reference signal; Filter2 is a low pass filter, is used for filtering high-frequency harmonic component.AD8099 is the high accuracy low distortion amplifier among Fig. 7, is used for buffering and amplifies.AD8302 is integrated phase demodulation amplitude discriminator among Fig. 8, is used to obtain amplitude ratio and phase contrast with respect to reference signal.The input of the output map interlinking 7 of Fig. 6, both produce pumping signal jointly, and pumping signal is after-applied to excitation coil through power amplifier.Another group circuit identical with Fig. 6 and Fig. 7 produces reference signal, directly receives the REF end of Fig. 8.Detected response signal on the measurement coil is connected to the SIN end of Fig. 8.Fig. 8 realizes the detection of phase place, the phase contrast between VP end output measuring-signal and the reference signal.
Noncontact cerebral edema monitoring method of the present invention is all inequality with rich grace patent aspect three of monitoring mode, monitoring principle, ranges of application etc.: the method that 1. rich grace patent adopts contact to paste electrode at head, the present invention adopts contactless excitation, measures the method for coil.2. rich grace patent adopts and detects the principle that corresponding current field changes, and the present invention adopts and detects the principle that induced field changes.3. the method for rich grace patent only can be used for the detection that head does not have the cerebral edema of wound, and the present invention can be to various cerebral edema patient's continuous monitorings except the detection that is used for cerebral edema.
Claims (4)
1. the monitoring method that changes of a non-contact magnetic inductive brain distribution of conductivity, it is characterized in that, this method is utilized the EDDY CURRENT principle, the magnetic induction one-dimension information is detected and the method for magnetic induction image is used for the monitoring of brain distribution of conductivity variation, comprises the following steps:
With excitation coil and measure coil be placed on monitoring objective around; In excitation coil, apply alternating current, then can produce alternating magnetic field, be designated as excitation field B0; The monitoring objective that is positioned at the alternating magnetic field territory forms the alternation eddy current of inducting because of the electromagnetic induction effect, and the intensity of this eddy current and the main distribution of conductivity by monitoring objective inside that distributes are determined; This eddy current produces induced field Δ B simultaneously, and changes former excitation field; By measuring coil, can detect amplitude and the phase place of induced field Δ B; When the distribution of conductivity of monitoring objective inside changes, the intensity of the eddy current of inducting and the also change thereupon that distributes, thus make the induced field Δ B on the magnetic test coil also change;
Measure the induced field Δ B of gained, can reflect the distribution of conductivity situation of monitoring objective inside; Therefrom extract the one dimensional numerical and the curve of distribution of conductivity or its variation, perhaps reconstruct distribution of conductivity two dimension or 3-D view, or distribution of conductivity topography; Thereby realize monitoring to the variation of brain distribution of conductivity;
The excitation coil of described excitation coil and measurement coil and measurement coil arrangement mode are respectively:
A. the excitation coil that quantity is equal to and measure coil rounded, uniformly-spaced be arranged in around the monitoring objective; Successively single excitation coil is applied excitation, and all are measured coil detect, to realize that imaging is carried out in the monitoring objective internal electrical conductance distribution of hub of a spool section of living in; By faultage image, with position and the variation tendency that reflects that this monitoring objective internal electrical conductance changes;
B. the excitation coil that quantity is equal to and measure coil linearly shape be arranged in the one or both sides of monitoring objective; Change excitation coil successively and measure coil, can carry out the monitoring of magnetic induction one-dimension information monitoring objective; By comparing the result of each time measurement, can reflect projected position and variation tendency that monitoring objective internal electrical conductance changes;
C. excitation coil that quantity is equal to and measurement coil constitute planar array respectively, two parallel both sides that are placed on monitoring objective of array, and a side is the excitation coil array, opposite side is the slotted line coil array; Apply synchronous alternating current in the excitation coil array, then the place can form proximate parallel magnetic field in the middle of coil array; Successively each coil in the slotted line coil array is detected, so that monitoring objective is mapped to picture; By map image, general status and variation tendency that reflection monitoring objective internal electrical conductance distributes.
2. the method for claim 1 is characterized in that, conglobate excitation coil of described arrangement and slotted line number of turns amount are respectively 6 or 8 or 10 or 12 or 14 or 16 or 32.
3. the method for claim 1 is characterized in that, the described excitation coil that is arranged in the one or both sides of monitoring objective is respectively 2 or 4 or 6 or 8 with the quantity of measuring coil.
4. the method for claim 1 is characterized in that, described excitation coil and the slotted line coil array that is arranged in a side of monitoring objective is that excitation coil is arranged in together, measures coil and comes together.
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| CN101822541B (en) * | 2009-03-06 | 2011-09-28 | 沈阳工业大学 | Resonant magnetic induction bioelectrical impedance tomography method and equipment adopted by same |
| CN101849818B (en) * | 2010-06-03 | 2012-11-14 | 中国人民解放军第三军医大学 | Device for checking type of cerebral edema |
| CN102499681A (en) * | 2011-10-17 | 2012-06-20 | 中国人民解放军第四军医大学 | Rotation-type coil group applicable to magnetic induction tomography and arrangement method thereof |
| CN102579009B (en) * | 2012-02-27 | 2013-10-23 | 重庆博恩富克医疗设备有限公司 | Electric signal processing unit for monitoring hydrocephalus and encephaledema |
| CN103006185B (en) * | 2012-12-19 | 2015-06-17 | 中国人民解放军第四军医大学 | Device and method for non-contact magnetic induction impedance plane projection imaging |
| CN103126671B (en) * | 2013-03-27 | 2015-08-19 | 中国人民解放军第三军医大学 | A kind of non-contacting magnetic inductive cerebral hemorrhage detection system |
| US10185011B2 (en) * | 2014-04-16 | 2019-01-22 | Koninklijke Philips N.V. | EPT method of electric conductivity reconstruction with enhanced stability and speed |
| US11241187B2 (en) * | 2014-11-03 | 2022-02-08 | Qian Xia | Electromagnetic wave sensing and modulating of neuronal activities |
| CN104783800A (en) * | 2015-05-05 | 2015-07-22 | 天津工业大学 | Lung respiration monitoring system based on magnetic detection electrical impedance imaging |
| GB201522661D0 (en) * | 2015-12-22 | 2016-02-03 | Univ Sheffield | Apparatus and methods for determining electrical conductivity of tissue |
| CN105997070B (en) * | 2016-06-15 | 2019-02-15 | 合肥工业大学 | A kind of contactless magnetic induction image system and its imaging method |
| WO2018039600A1 (en) * | 2016-08-26 | 2018-03-01 | AMI Research & Development, LLC | Vital sign monitoring via touchscreen using bioelectric impedance |
| CN106725468B (en) * | 2016-11-22 | 2020-10-20 | 天津大学 | Multi-frequency electromagnetic tomography method for cerebral hemorrhage detection |
| CN106901733B (en) * | 2017-02-20 | 2020-01-17 | 天津大学 | Multi-frequency electromagnetic tomography method for inhibiting mutual inductance coupling effect between tissues |
| CN108670252A (en) * | 2018-05-15 | 2018-10-19 | 苏州迈磁瑞医疗科技有限公司 | A kind of contactless head average dielectric constant measurement method |
| CN108937928A (en) * | 2018-06-12 | 2018-12-07 | 李长寿 | A kind of Medical electromagnetic induction type three uses diagnostic equipment |
| CN110680320B (en) * | 2019-10-25 | 2020-11-06 | 深圳技术大学 | Magnetic induction imaging method and system |
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