Patent ID: 6269262
Filing Date: 2001-07-31
Classification: A61B

Abstract:
A biomagnetic field measurement apparatus comprising:a shielded room;a bed which is adapted to hold a subject to be inspected in said shielded room;a cryostat in which a plurality of SQUID magnetometers are arranged at low temperature, wherein said cryostat is arranged in said shielded room and the plurality of SQUID magnetometers detect a normal component of a magnetic field generated from a heart of a fetus in said subject to be inspected;a gantry which is adapted to hold said cryostat, and which is arranged in said shielded room;a driving and detecting circuit which drives the plurality of SQUID magnetometers and detects signals from the plurality of SQUID magnetometers;an electrocardiograph which is used to obtain an electrocardiogram of said subject to be inspected, wherein the measure of said electrocardiogram and the measurement of the normal component of said magnetic field are carried out simultaneously;a computer which collects the signals from said driving and detecting circuit and collects signals from said electrocardiograph, and processes the signals from said driving and detecting circuit to obtain a magnetic field waveform expressing a temporal change of said magnetic field, and to obtain a distribution of the magnetic field in the heart of the fetus and a distribution of an electric current in the heart of the fetus, wherein said computer calculates said distribution of the magnetic field by an equation of (dB.sub.z +L /dx).sup.2 +L +(dB.sub.z +L /dy).sup.2 +L , where (x, y, z) are Cartesian coordinates and B.sub.z is said normal component of said magnetic field, and calculates said distribution of the electric current by 90.degree. counter-clockwise rotation of a vector of the differential values (dB.sub.z /dx, dB.sub.z /dy); anda display which displays said magnetic field waveform and which is arranged in said shielded room such that an operator positioning a lower surface of said cryostat with respect to said subject to be inspected can observe said magnetic field waveform on said display.