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EP0449231A1
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Process and apparatus for measuring the biocurrent distribution
Assignee: Hitachi Ltd
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Filing: 1991-03-26
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Granted: —
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Expires: 2011-03-26
Abstract
Abstract A process and an apparatus for measuring the biocurrent distribution are disclosed. Multiple current more than the number of isolated currents possibly existing in a living body are assumed and the virtual magnetic field created by the assumed currents at actual measuring points (12-1, ..., 12-M) is calculated. The estimated location and current vectors of said assumed currents are consecutively changed to decrease the difference between said virtual and actual magnetic fields so that the estimated location and current vectors of the assumed currents having the number corresponding to the true isolated currents substantially approximate to the true values and the estimates of the other assumed currents approximate to zero. This enables the biocurrent distribution to be exactly determined even when the number of isolated currents (q n ) is not preliminarily known.
Inventors
- 👤 Kensuke Sekihara
- 👤 Nagaaki Ohyama
- 👤 Hideaki Haneishi
- 👤 Toshio Honda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 02:45
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/24; A61B5/242; G; G06; G06F; G06F2218/00; G06F2218/22
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
181 words
A process for measuring the distribution of the biocurrent by measuring the biomagnetic field generated by the activity of a living body at a plurality of measuring points (12-1, ..., 12-M) to indirectly determine the distribution of the isolated currents (q n ) in said living body from the plural measured values of the magnetic field, comprising the steps of: measuring the actual magnetic field at said measuring points (12-1, ..., 12-M); assuming multiple currents move than the number of said isolated currents possibly existing in said living body to preset the locations and the current vectors of the assumed currents; calculating a virtual magnetic field at each measuring point from the estimated location and current vectors; and determining including consecutively changing the estimated location and current vectors of said assumed currents to decrease the difference between said virtual and actual magnetic fields so that the estimated location and current vectors of the assumed currents having the number corresponding to the true isolated currents substantially approximate to the true values and the estimates of the others assumed currents approximate to zero.
Claim 2
Dependent Claim
69 words
A process for measuring the biocurrent distribution as defined in Claim 1 in which said determining step includes the steps of: a changing said estimated location and current vectors; calculating a first amount representative of the difference between said virtual and actual magnetic fields; calculating a second amount from each of said estimated current vectors; and determining said estimated location and current vectors from said first and second amounts.
Claim 3
Dependent Claim
50 words
A process for measuring the biocurrent distribution as defined in Claim 2 in which said step of determining said estimated location and current vectors includes presetting a cost function including at least said first and second amounts and determining the estimated location and current vectors by using the cost function.
Claim 4
Dependent Claim
26 words
A process for measuring biocurrent distribution as defined in Claim 3 in which said cost function includes a linear sum of said first and second amounts.
Claim 5
Dependent Claim
31 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said step of determining said estimated location and current vectors is executed by minimizing the cost function.
Claim 6
Dependent Claim
30 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said second amount is the total sum of the absolute values of said estimated current vectors.
Claim 7
Dependent Claim
40 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said second amount is the total sum of the α-th power (α is a positive real number) of the absolute values of said estimated current vectors.
Claim 8
Dependent Claim
42 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said second amount is the total sum of the absolute values of the magnetic fields, each created at each measuring point by each of said assumed current vectors.
Claim 9
Dependent Claim
54 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said second amount is the total sum of the absolute values of the magnetic field's components normal to the surface of said living body, each magnetic field being created by each of said assumed current vector at each measuring point.
Claim 10
Dependent Claim
62 words
A process for measuring the biocurrent distribution as defined in Claim 4 in which said second amount is the total sum of α-th power (α is a positive real number) of absolute values of the magnetic field's components normal to the surface of said living body, each magnetic field being created by each of said assumed current vector at each measuring point.
Claim 11
Dependent Claim
25 words
A process for measuring the biocurrent distribution as defined in Claim 7 or 12, in which α ≠ 1, preferably 0 < α < 1.
Claim 12
Dependent Claim
74 words
A process for measuring the biocurrent distribution as defined in Claim 5 in which said step of determining said estimated location and the current vectors includes a first step of accepting a change in said estimates executed in the step of changing said estimates when said cost function decreases, and a second step of accepting a change in said estimates in a probability relating to a given temperature even when said cost function increases.
Claim 13
Independent Claim
182 words
An apparatus of measuring the biocurrent distribution by measuring the magnetic field generated by the activity of a living body at a plurality of measuring points (12-1, ..., 12-M) to indirectly determine the distribution of isolated currents (q n ) in the living body from the plural measured values of the magnetic field, comprising: means for measuring the actual magnetic field at said measuring points (12-1 ..., 12-M); means for assuming multiple currents more than the number of said isolated currents possibly existing in said living body to preset the location and the current vectors of the assumed current; means for calculating a virtual magnetic field at each measuring point from the estimated location and current vectors; and determining means including consecutively changing the estimated location and current vectors of said assumed currents to decrease the difference between said virtual and actual magnetic fields so that the estimated location and current vectors of the assumed currents having the number corresponding to the true isolated currents substantially approximate to the true values and the estimates of the other assumed currents approximate to zero.
References Cited (Backward Citations)
US4486835A
Cited
DE3725532A1
Cited
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