METHOD AND SYSTEM FOR IN-VIVO TEMPERATURE MEASUREMENT BASED ON AC MAGNETIZATION OF MAGNETIC NANOPARTICLE

摘要

The invention discloses a method for in-vivo temperature measurement based on AC magnetization of magnetic nanoparticles, and relates to a nano test technology field. The invention positions magnetic nano agent at an area of a measured object, applies an AC excitation magnetic field to the area of the magnetic nano agent, collects an AC magnetization signal of the magnetic nano agent under the AC excitation magnetic field, detects amplitudes of odd harmonics of the AC magnetization signal, and finally calculates in-vivo temperature according to a relationship between the odd harmonics and the in-vivo temperature. The invention predetermines the relationship between the odd harmonics and the in-vivo temperature via the discrete Langevin's function and the Fourier transformation, solves the in-vivo temperature according to the relationship without considering concentration of the magnetic nanoparticles, and effective moment as temperature varies, and thus accurately detecting the in-vivo temperature.

主权项

1. A method for in-vivo temperature measurement, comprising steps of:
(1) positioning a magnetic nano agent at an area of a measured object; (2) applying an AC excitation magnetic field to said area of said magnetic nano agent; (3) collecting an AC magnetization signal of said magnetic nano agent under said AC excitation magnetic field; (4) detecting amplitudes C1, C3, . . . , C2n-1 of odd harmonics of said AC magnetization signal, a number of said odd harmonics n≧1; and (5) calculating in-vivo temperature T according to a relationship between said odd harmonics and said in-vivo temperature X=AY, wherein said amplitudes of said odd harmonics form a column vectorX=[C1C3⋮C2n-1]; wherein a coefficient matrix A is defined as: said AC magnetization signal is expressed via Langevin's function, and expression of said amplitudes of said odd harmonics is deduced from a Taylor series expansion of the Langevin's function, and thus said coefficient matrixA= [Ms2H0a1,1kMs4H03a1,2k3Ms6H05a1,3k5…Ms2mH02m-1a1,mk2m-10Ms4H03a2,2k3Ms6H05a2,3k5…Ms2mH02m-1a2,mk2m-1⋮⋱⋱⋱⋮⋮(0)⋱⋱Ms2mH02m-1an-1,mk2m-10……⋱Ms2mH02m-1an,mk2m-1],whereto Ms is effective magnetic moment of a magnetic nanoparticle, k is a Boltzmann's constant, H0 is an amplitude of said AC excitation magnetic field, au,v is a coefficient of an element at the uth row and the vth column of said coefficient matrix A, where u=1, 2, . . . , n, v=1, 2 . . . , m, and m is a number of Taylor's expansion terms, and m≧n;
wherein a related column vector Y of said in-vivo temperature is expressed asY=[NTNT3⋮NT2m-1],where T is said in-vivo temperature of said measured object, and N is magnetic nano concentration at said measured object.