Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-04-19
2001-08-14
Jeffery, John A. (Department: 3742)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C324S248000
Reexamination Certificate
active
06275719
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic field measurement apparatus using a SQUID (Superconducting Quantum Interference Device) for measuring a very small magnetic field generated from hearts and brains of an adult, an infant and a fetus or the like, and particularly to a biomagnetic field measurement apparatus for displaying a magnetic field wave form generated from a heart of a fotus and the position of the heart of the fotus.
When a biomagnetic field measured by a conventional biomagnetic field measurement apparatus is displayed, it is customary that a magnetic wave form is displayed at every channel as it is or a contour map at a certain time point is displayed. Also, there is known a Dewar apparatus in which a sensor position can be finely adjusted easily and freely in accordance with a subject to be inspected or the like (Japanese Patent Laid-open No.297456/1995).
SUMMARY OF THE INVENTION
According to the prior art, when a position of a heart of a fotus is moved within a womb by the movements of the fotus, as a method of monitoring the movements of the fotus and heart rate, there are known a delivery monitor apparatus (Handbook of Clinical Engineering, pp.474-475 (1984)) and a ultrasonic diagnosis apparatus. There is not realized a method of measuring a fotus based on a magnetic wave form obtained by a biomagnetic field measurement apparatus. There is then the problem that it is difficult to understand an aging change of the health of a fotus. An object of the present invention is to provide a biomagnetic field measurement apparatus in which a position of a current dipole (hereinafter simply referred to as a dipole) is estimated and the dipole is displayed on a monitor as a position of a heart of a fotus, thereby resulting in the movements of the fotus and the variation of the heart rate being observed.
According to the present invention, there is provided a biomagnetic field measurement apparatus which is comprised of a plurality of magnetometers each having a SQUID sensor and a detection coil and each detecting a magnetic field generated from a heart of a fotus in a mother, a processor processing magnetic field wave forms detected by the magnetometers and a display displaying results obtained by the processor, wherein the processor estimates a position of a current dipole from the magnetic field wave forms, and processes projecting the position of the current dipole on a first plane parallel to a plane on which one ends of the magnetometers are disposed and processes projecting the position of the current dipole on a second plane perpendicular to the plane on which the one ends of the magnetometers are disposed, and wherein the position of the current dipole projected on the first plane and the position of the current dipole projected on the second plane are displayed on the display. More in detail, the processor executes the processing for estimating the position of the dipole from the magnetic field wave form and the processing in which the position of the dipole is expressed as the position of the heart of the fotus and the position of the dipole is projected onto the plane parallel to and perpendicular to the plane (or the bottom surface of the cryostat for housing magnetometers) in which the tip end portions of a plurality of magnetometers are disposed, and the display means displays results obtained when the position of the dipole is projected onto the parallel plane and the vertical plane.
The biomagnetic field measurement apparatus according to the present invention has the following characteristics:
(1) estimating the position of one dipole from the magnetic field wave form; (2) estimating the position of the dipole at a time point in which the peak value of the magnetic wave form is detected; (3) display means displays a plane of (x, y, z) space on which the position of the dipole is projected; (4) display means projects results obtained when the magnetometer is projected onto the parallel plane and the perpendicular plane; (5) display means displays a time change of the position of the dipole, and display means displays a route indicating the time change of the position of the dipole; (6) display means displays the route indicating the time change of the position of the dipole with numerals; (7) display means displays the route indicating the time change of the position of the dipole with arrows; (8) display means displays the position of the dipole by changing the color depending on the magnitude of the dipole; (9) display means displays a movement speed of the position of the dipole; (10) display means displays a movement distance of the position of the dipole; (11) display means displays a rotation amount in the direction of the dipole; (12) display means displays the time change of the heart rate of the fotus calculated from the magnetic field wave form; (13) display means displays a power spectrum of a time change of a heart rate of a fotus calculated from the magnetic field wave form. (14) Each magnetometer has detection coils formed on one bobbin for detecting components of three directions perpendicular to each other in magnetic field, and tip end portions of a plurality of the bobbins are disposed in a matrix fashion. (15) Display means displays magnetic field wave forms in response to the layout of the tip end portions of a plurality of bobbins. (16) Display means displays components of three directions perpendicular to each other detected by each magnetometer of a plurality of magnetometers on different regions at every direction of the three directions. (17) The processor executes any of the filtering for eliminating a noise lower than or equal to 5 Hz to 6 Hz (e.g. 1 Hz, 2 Hz, 3 Hz) generated in accordance with respiration of a mother, the adding processing of magnetic field wave forms and the peak detection processing of magnetic field wave forms.
As described above, the state of the movements of the foetus can be easily monitored from the position and the state of the heart of the fetus displayed on the display in a two-dimensional fashion and the variation of the heart beat can be analyzed with ease.
A biomagnetic field measurement apparatus comprises a plurality of magnetometers each detecting magnetic field generated from a subject to be inspected, a cryostat which holds the magnetometers at a low temperature by a cooling liquid, a member holding the cryostat and a spherical member in which the cryostat is installed, wherein the member holding the cryostat has a hole in which the spherical member can rotate.
Also, a biomagnetic field measurement apparatus comprises a plurality of magnetometers each detecting magnetic field generated from a subject to be inspected and a cryostat which holds the magnetometers at a low temperature by a cooling liquid, wherein a member having humidity is disposed on a part of the cryostat, or a heating member is disposed on a part of the cryostat. Further, a biomagnetic field measurement apparatus comprises a bag-like member for capturing a cooling gas evaporated from the inside of the cryostat on the upper portion of the cryostat and a member for filling a gas generated from the cooling liquid in the cryostat at an upper part of the cryostat.
Also, a biomagnetic field measurement apparatus comprises a plurality of magnetometers each detecting magnetic field generated from a subject to be inspected, a cryostat which holds the magnetometers at a low temperature by a cooling liquid and a member holding the cryostat, wherein, in the cryostat, a first tube for introducing the cooling liquid into the cryostat and a second tube which has a shape of a funnel tube at one end and into which one end of the first tube can be inserted.
Further, a biomagnetic field measurement apparatus comprises a plurality of magnetometers each having a SQUID sensor and a detection coil and each detecting magnetic field generated from a subject to be inspected, a cryostat which holds the magnetometers at a low temperature by a cooling liquid, a holding member which holds the cryostat such that the cryostat
Kandori Akihiko
Miyashita Tsuyoshi
Sasabuchi Hitoshi
Suzuki Hiroyuki
Tsukada Keiji
Hitachi , Ltd.
Jeffery John A.
Mattingly, Stanger & Malur
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