A first-order gradient compensation module and method for unshielded magnetocardiograph

Abstract

The invention relates to a first-order gradient compensation module and method for an unmask magnetocardiography. The first-order gradient compensation module is characterized by consisting of three introduced z-directional reference magnetometers and z-directional reference magnetometers in a known triaxial module, wherein the three introduced z-directional reference magnetometers are respectively SQz1, SQz2 and SQz3, the SQz1 and the SQz2 and the SQz of the triaxial module are arranged in the same plane, and the SQz3 and the SQz are in the same axes. The compensation method comprises the following steps of 1) constructing the first-order gradient compensation module and keeping the relative position of the module and gradiometer to be constant; 2) performing low-temperature testing and optimizing software algorithm; and 3) collecting a real solid magnetic signal. The first-order gradient compensation module is not limited for an unmask magnetocardiography, and is suitable for multi-channel unmask or masked magnetocardiography.

Description

technical field [0001] The invention relates to a first-order gradient compensation module and method for an unshielded magnetocardiograph. Background technique [0002] The magnetocardiograph can detect the weak magnetic field generated during the electrophysiological activity of the heart. It has special advantages such as high sensitivity, complete non-invasiveness, complete passiveness, and non-contact. It is expected to become a new generation of high-end medical clinical research and clinical diagnostic equipment for high-risk groups Health screening and early diagnosis of coronary heart disease [M.Hamalainen et al, Magnetoencephalography-theory, instrumentation, and applications to noninvasive studies of the working human brain, Rev.Mod.Phys.65(2), 413(1993)]. [0003] The diagnostic ability and reliability of a magnetocardiograph depends on the quality of the detected magnetic signal, and the typical strength of the adult human heart is 100pT (1pT=10 -12 T), is only...

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Problems solved by technology

[0004] The noise suppression method in the magnetic field measurement in an unshielded environment mainly uses the gradiometer technology, but due to the imperfect manufacturing process of the hardware gradiometer support material and the existence of manual winding errors and other factors, the gradiometer has a certain degree of imbalance. The degree of balance makes the hardware gradiometer respond to both the uniform field and the gradient field in the ambient magnetic field [J.VRBA, J.MCCUBBLN, First-Gradient Balancing of Higher-Order Gradiometers.Il Nuovo Cimento D.Volume 2, Number 2(1983) ,142-152】

In order to further improve the noise suppression ability of the hardware gradiometer, a three-axis reference magnetometer is usually used to compensate the background field. The compensation algorithms adopted mainly include frequency least squares, time domain least squares, etc. 【Shulin Zhang, Yongliang Wang, Huiwu Wang, Shiqin Jiang and XiaomingXie, Quantitative evaluation of signal integrity for magnetocardiography, Phys.Med.Biol.54(2009)4793], while the three-axis reference magnetometer mainly suppresses the response of the gradiometer to the uniform component of the environmental field, while the Its gradient response, especially the first-order gradient response, has limited suppression ability

Therefore, when the magnetic gradient environment in the application environment of the unshielded magnetocardiograph (the source of the magnetic gradient includes mechanical vibration of the magnetocardiograph, interference from nearby high-power electrical equipment, etc.) The ratio will decrease, thereby reducing the diagnostic ability and system reliability of the magnetocardiograph

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