CN103284723B - High-field magnetic resonance scanning safety testing body model system, high-field magnetic resonance scanning safety testing method and magnetic resonance system - Google Patents
High-field magnetic resonance scanning safety testing body model system, high-field magnetic resonance scanning safety testing method and magnetic resonance system Download PDFInfo
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Abstract
The invention discloses a high-field magnetic resonance scanning safety testing body model system, a high-field magnetic resonance scanning safety testing body model method and a magnetic resonance system with the high-field magnetic resonance scanning safety testing body model system. The high-field-magnetic resonance scanning safety testing body model system comprises a radio frequency electric field measuring module, a bionic object body model and a computation processing module, the bionic object body model is positioned in a working area of the magnetic resonance system, the radio frequency electric field measuring module detects a radio frequency electric field of a target portion of the bionic object body model and obtains an equivalent value of the radio frequency electric field of the target portion, and the processing module computes to obtain a magnetic resonance scanning radio frequency Local SAR (specific absorption rate) value of the target portion according to the obtained equivalent value of the radio frequency electric field measuring module and a dielectric parameter of the target portion of a bionic object body model system. By means of comparing a Local SAR1 value obtained by the high-field magnetic resonance scanning safety testing body model system with a Local SAR2 value automatically obtained by the magnetic resonance system via bionic object body model scanning, the Local SAR2 value given by the magnetic resonance system is verified, and accordingly the safety of magnetic resonance scanning is guaranteed.
Description
Technical field
The invention belongs to High-Field and super high field magnetic resonance body scans security technology area, be specifically related to a kind of high-field magnetic resonance scanning security test body mould system and method for testing thereof and there is the magnetic resonance system that this high-field magnetic resonance scans security test body mould system.
Background technology
Nuclear magnetic resonance (Magnetic resonance imaging, MRI) have soft tissue resolution high, functional imaging can be carried out, to human body without outstanding advantages such as ionizing radiation, extensive application in clinical practice.The image quality key index such as spatial resolution, temporal resolution, signal to noise ratio of MRI all can along with main field (B
0) raising of field intensity and being increased dramatically.Therefore, high field intensity MRI is inevitable development trend.Along with B
0field field intensity significantly increases, and while namely MRI resonant frequency significantly improves, the radio-frequency (RF) energy that biological tissue absorbs also significantly promotes.It is exactly that tissue temperature raises that biological tissue absorbs the most obvious biological effect of radio-frequency (RF) energy.In certain tolerance band, human body can regulate blood circulation, sweat gland secretion etc. by nerve centre, maintains the environment of constant body temperature.If but organize radio frequency energy absorption too much, exceed the tolerance range of human body self regulation, just there will be Thermoregulatory disorders, cause the series of problems such as metabolic disturbance of electrolyte, nerve problems.If concentrate in the radio-frequency (RF) energy short time irradiation in local, local tissue temperature can be caused to raise, so local organization may be caused to burn, necrosis etc.Therefore, the absorption of biological tissue radio frequency energy in effective monitoring MR scanning process is the important subject that high field MRI checks safety aspect.
Radio-frequency (RF) energy specific absorption rate, i.e. specific absorption rate(SAR, unit is W/Kg) be the parameter of the degree of absorption characterizing biological tissue radio frequency energy, be usually divided into whole body SAR value, body SAR value and local SAR(Local SAR) value.Whole body SAR value (whole-body SAR) or body SAR value (partial body SAR), refer in the radio frequency exposure time allowed, at systemic body-wide, or within the scope of irradiated body, the average RF energy work rate of every kilogram of tissue resorption.Local SAR value refers in the radio frequency exposure time allowed, everywhere the average RF energy work rate of every gram of tissue resorption in tissue.Visible, whole body SAR value or body SAR value, refer to the meansigma methods of the radio-frequency (RF) energy power that tissue absorbs in a big way, and Local SAR value, be then equivalent to the radio-frequency (RF) energy power that in tissue, every " point " absorbs.
If human body somewhere Local SAR value exceeds standard, mean and create " focus " (Hot Spot) at this place, this tissue injury of place may be caused even downright bad.It is emphasized that the damage that brings of this hot localised points is recessive often, usually do not have obvious clinical symptoms, easily out in the cold clinically.Under normal circumstances, even if whole body SAR value and body SAR value all meet safety criterion, do not represent the Local SAR value that body interior organizes everywhere yet and all necessarily meet safety criterion equally.
Existing clinical high field MR systems all can measure various SAR value when scanning automatically.Wherein, whole body SAR value or body SAR value, measure relatively simple, however the Accurate Determining of Local SAR value but difficulty is larger.The result obtained based on the simulation calculation of the multiple dielectric parameter of certain Electromagnetic model of human body and in vitro tissue that clinical MR system adopts accurately can not reflect the true distribution of the Local SAR value of Different Individual under High-Field MR.
Under scanning in order to ensure clinical High-Field MR, the absorption of tissue radio frequency energy is everywhere all within the scope of secure threshold, and existing high field MR systems often on the basis of simulation result, can only take the way of reserved larger safety margin.This way had both had certain blindness, also limited the performance of device systems performance to a certain extent.Obviously, the Local SAR value of human body biological tissue inside directly can not be measured with in probe or sensor intervening body, and it must be noninvasive for being applicable to the clinical Local SAR value assay method generally used.Because biological tissue Local SAR value Non-invasive measurement relates to MR radio-frequency field (B
1), tissue and B
1the each side basic research such as field interactions, tissue electromagnetic property, acquire a certain degree of difficulty.Due to high-field magnetic resonance Local SAR value quantitative determination problem increasing to become and become more and more important along with magnetic resonance B0 field, but never perfect solution.
At present, Local SAR value quantitative determination method mainly contains two large classes, respectively: based on the emulated computation method of Electromagnetic model of human body with B
1field reflection (B
1mapping) the MR scanning survey computational methods and based on the multiple dielectric parameter measurement technology of MR human body.
Local SAR value simulation calculation side based on Electromagnetic model of human body applies certain Electromagnetic model of human body, under being placed in specific MR radio-frequency coil, arranges certain radio frequency reading parameter, calculates B
1the distribution of field in tissue, with reference to the multiple dielectric parameter of in vitro tissue, obtains the Local SAR value of tissue.In this method, B
1the calculating of field is extremely important, because tissue belongs to electromagnetic load heterogeneous, so the calculating of electromagnetic field adopts Fdtd Method (FDTD) algorithm usually.
Greatest drawback based on the Local SAR value emulated computation method of Electromagnetic model of human body is: calculate Local SAR value owing to setting up personalized whole body electromagnetic model for each individual patient, workload is too large and unrealistic, so general human body electromagnetic model can only be adopted, cause there is relatively large deviation when individual variation is large between Local SAR value result of calculation and actual value.In addition, with reference to the multiple dielectric parameter of in vitro tissue during owing to calculating, and between the multiple dielectric parameter of in vitro tissue and the multiple dielectric parameter of biological tissue, there is some difference, and this species diversity also can cause result of calculation to occur deviation.
With B
1mR scanning survey computational methods based on the multiple dielectric parameter linear measurement technology of Mapping and MR human body, within nearly 2 years, being developed rapidly, is one of High-Field MR research field focus.Katscher etc. propose and adopt B
1mapping technology determines the method organizing conductivity and Local SAR value, but the method is just verified on uniform body mould.Voigt etc. proposed the linear measurement method of the multiple dielectric parameter of brain tissue in 2011, and the Local SAR value computational methods based on multiple dielectric parameter proposed in 2012 on this Research foundation for biological tissue, but be only verified in the live body MR of brain scans, whole body can't be applied to, and error calculated is about 20%, accuracy is not ideal enough, need to improve.
Up to now, although research worker has given the survey calculation method of some Local SAR value, it has been the difficult problem thoroughly do not solved that High-Field MR scans lower personalized body tissue Local SAR value noinvasive quantitative determination always.Lower tissue safety is scanned in order to ensure High-Field MR, be necessary very much to provide a kind of high-field magnetic resonance Local SAR test body modular system, the Local SAR estimated value that current clinical system provides is verified, guarantees the radio frequency safety that the clinical High-Field of objective detecting and super magnetic resonance system scan patient.
Therefore, not enough for prior art, provide a kind of high-field magnetic resonance to scan security test body mould system and method for testing thereof and to have the magnetic resonance system of this high-field magnetic resonance scanning security test body mould system very necessary to overcome prior art deficiency.
Summary of the invention
An object of the present invention is for prior art not enough, a kind of high-field magnetic resonance is provided to scan security test body mould system, when carrying out magnetic resonance imaging, this system is placed in magnetic resonance imaging region, this system can calculate the Local SAR1 value obtaining target site, magnetic resonance scanning system can calculate the Local SAR2 value of this imitative organisms mould automatically simultaneously, by comparing Local SAR1 value and Local SAR2 value, the Local SAR2 value that magnetic resonance scanning system provides is verified.
Above-mentioned purpose of the present invention is achieved through the following technical solutions:
A kind of high-field magnetic resonance scanning security test body mould system, is provided with rf electric field measurement module, imitative organisms mould and computing module;
Described imitative organisms mould is placed in the working region of magnetic resonance system, the rf electric field of the target site of the described imitative organisms mould of described rf electric field measurement module detection also obtains the rf electric field equivalence value of target site, the dielectric parameter of the rf electric field equivalence value that described processing module obtains according to described rf electric field measurement module and described bionical object body mould system target site, calculates the magnetic resonance imaging radio frequency Local SAR value obtaining target site.
Above-mentioned imitative organisms mould is provided with the cavity of simulation human anatomic structure, be filled with bionical fabric texture dielectric material in described cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in described cavity, different parts is filled and the electromagnetic parameter of the corresponding position of tissue match.
Above-mentioned dielectric material is the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous.
Above-mentioned rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit;
Described probe unit detects the rf electric field value of described imitative organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to described rf electric field signal transmission unit, described power supply signal is delivered to described rf electric field equivalence value measuring unit by described rf electric field signal transmission unit, and described rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site.
Above-mentioned probe unit is provided with sensor, described rf electric field signal transmission unit is provided with analog-digital converter, the outfan of described sensor is connected with the input of described analog-digital converter, and the outfan of described analog-digital converter is connected with the input of described rf electric field signal transmission unit;
Described sensor is dipole antenna configuration, described dipole both arms separately length L be set to 10mm, gap H between described dipole both arms is set to 2mm, be provided with Schottky diode D between described dipole both arms, described dipole both arms be connected to the input of described analog-digital converter by high impedance wire.
Above-mentioned computing module installation has collecting unit, computing unit and result output unit;
The input of described collecting unit is connected with the outfan of described rf electric field equivalence value measuring unit, and the outfan of described collecting unit is connected with the input of described computing unit;
Described computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency Local SAR value;
Above-mentioned computing module is also provided with display unit, and described display unit is connected with the outfan of described result output unit.
High-field magnetic resonance scanning security test body mould system provided by the invention, is provided with rf electric field measurement module, imitative organisms mould and computing module; Described imitative organisms mould is placed in the working region of magnetic resonance system, the rf electric field of the target site of the described imitative organisms mould of described rf electric field measurement module detection also obtains the rf electric field equivalence value of target site, the dielectric parameter of the rf electric field equivalence value that described processing module obtains according to described rf electric field measurement module and described bionical object body mould system target site, calculates the magnetic resonance imaging radio frequency Local SAR value obtaining target site.When carrying out high-field magnetic resonance scanning, the magnetic resonance imaging radio frequency Local SAR1 value obtaining target site is calculated by high-field magnetic resonance scanning security test body mould system, pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that described imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified.The Local SAR value that the present invention can provide magnetic resonance system verifies, thus ensures the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
Another object of the present invention is to provide a kind of high-field magnetic resonance to scan method for testing security, the method can verify the Local SAR2 value that magnetic resonance scanning system provides in noinvasive situation.
Above-mentioned purpose of the present invention is achieved through the following technical solutions:
A kind of high-field magnetic resonance scanning method for testing security, adopts above-mentioned high-field magnetic resonance to scan security test body mould system and tests, comprise the steps,
A, previously prepared imitative organisms mould, described imitative organisms mould is provided with the cavity of simulation human anatomic structure, be filled with bionical fabric texture dielectric material in described cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in described cavity, different parts is filled and the electromagnetic parameter of the corresponding site of tissue match; Described dielectric material is the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous;
To the mixture dielectric material of the imitative organisms mould of final preparation, use Network Analyzer to adopt coaxial detection method to measure its electrical conductivity and dielectric constant, electromagnetic dielectric parameter is matched with corresponding biological tissue's electromagnetic parameter;
B, described imitative organisms mould are placed at the working region of magnetic resonance system, described rf electric field measurement module is measured the rf electric field of the target site of imitative organisms mould and is obtained the rf electric field equivalence value of target site, the dielectric parameter at the rf electric field equivalence value that described processing module obtains according to described rf electric field measurement module and described bionical object body mould system test position, calculates the magnetic resonance imaging radio frequency Local SAR value of target site.
Above-mentioned rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit;
Described probe unit detects the rf electric field value of described imitative organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to described rf electric field signal transmission unit, described power supply signal is delivered to described rf electric field equivalence value measuring unit by described rf electric field signal transmission unit, and described rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site;
Described probe unit is provided with sensor, described rf electric field signal transmission unit is provided with analog-digital converter, the outfan of described sensor is connected with the input of described analog-digital converter, and the outfan of described analog-digital converter is connected with the input of described rf electric field signal transmission unit;
Described sensor is dipole antenna configuration, described dipole both arms separately length L be set to 10mm, gap H between described dipole both arms is set to 2mm, be provided with Schottky diode D between described dipole both arms, described dipole both arms be connected to the input of described analog-digital converter by high impedance wire;
Described computing module installation has collecting unit, computing unit and result output unit;
The input of described collecting unit is connected with the outfan of described rf electric field equivalence value measuring unit, and the outfan of described collecting unit is connected with the input of described computing unit;
Described computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency SAR value;
Described step b specifically, the power supply signal at described sensor detection of a target position, carry out after analog digital conversion through analog-digital converter, be delivered to rf electric field equivalence value measuring unit, measured the rf electric field equivalence value obtaining target site by rf electric field equivalence value measuring unit;
Measured rf electric field equivalence value is delivered to the collecting unit of computing module installation by rf electric field equivalence value measuring unit;
High-field magnetic resonance scanning method for testing security provided by the invention, high-field magnetic resonance scanning security test body mould system is adopted to test, imitative organisms mould is placed at the working region of magnetic resonance system, measured the rf electric field of the target site of imitative organisms mould by rf electric field measurement module and obtain the rf electric field equivalence value of target site, and calculating the magnetic resonance imaging radio frequency Local SAR value of target site.Pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified, thus ensure the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
Another object of the present invention is to provide a kind of magnetic resonance system, this system can verify the Local SAR2 value that magnetic resonance scanning system provides in noinvasive situation.
Above-mentioned purpose of the present invention is achieved through the following technical solutions.
A kind of magnetic resonance system is provided, above-mentioned high-field magnetic resonance scanning security test body mould system, when carrying out high-field magnetic resonance scanning, the magnetic resonance imaging radio frequency Local SAR1 value obtaining target site is calculated by high-field magnetic resonance scanning security test body mould system, pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that described imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified, thus ensure the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
Accompanying drawing explanation
The present invention is further illustrated to utilize accompanying drawing, but the content in accompanying drawing does not form any limitation of the invention.
Fig. 1 is the schematic diagram of a kind of high-field magnetic resonance scanning of the present invention security test body mould system.
Fig. 2 is the schematic diagram of the probe unit of a kind of high-field magnetic resonance scanning of the present invention security test body mould system.
Detailed description of the invention
Describe the present invention below in conjunction with specific embodiment.
embodiment 1.
A kind of high-field magnetic resonance scanning security test body mould system, as shown in Figure 1, is provided with rf electric field measurement module, imitative organisms mould and computing module.
Imitative organisms mould is placed in the working region of magnetic resonance system, the rf electric field of the target site of the imitative organisms mould of rf electric field measurement module detection also obtains the rf electric field equivalence value of target site, the dielectric parameter of the rf electric field equivalence value that processing module obtains according to rf electric field measurement module and bionical object body mould system target site, calculates the magnetic resonance imaging radio frequency Local SAR value obtaining target site.
Imitative organisms mould is provided with the cavity of simulation human anatomic structure, bionical fabric texture dielectric material is filled with in cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in cavity, different parts is filled and the electromagnetic parameter of the corresponding position of tissue match, and make the electromagnetic parameter of the bionical electromagnetic parameter of fabric texture dielectric material and the corresponding position of tissue as far as possible close.
The dielectric material that imitative organisms mold cavity is arranged can be the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous, is mixed to form different dielectric constant and electrical conductivity by different proportion.Body mould dielectric material can also adopt the aqueous gelatin oil mixture of salt adding.Oil can adopt vegetable oil, and the oil of different content can simulate the tissue of different moisture content, comprises high-moisture tissue if muscle, tumor and low water content tissue are as fat, bone marrow etc., salt content number can change the size of electrical conductivity.Such as, be simulated muscle tissue phantom, the aqueous gelatin of 90% can be adopted, the vegetable oil of mixing 10%, then add salt (NaCl) according to the ratio of every 1000ml solution 6 grams; For simulated fat tissue, the aqueous gelatin of 15% can be adopted, the vegetable oil of mixing 85%, then add salt according to the ratio of every 1000ml solution 0.24 gram.
For the final mixture dielectric material formed, use Network Analyzer, adopt coaxial probe measuring method, measure its electrical conductivity and dielectric constant accurately, make the electromagnetic dielectric such as electrical conductivity and dielectric constant parameter as far as possible close with corresponding biological tissue's electromagnetic parameter.During measurement, measure the reflection coefficient at sample and coaxial cable interface
for:
， （2）
Wherein
for the characteristic impedance of coaxial line, be generally 50 Ω,
for the complex impedance of sample, jointly determined by the electrical conductivity of sample and dielectric constant, be generally:
, （3）
Here,
correspond to the resonant frequency of MRI system,
be multiple relative dielectric constant, its real part correspond to relative permitivity, and imaginary part correspond to electrical conductivity relative value.Due to the existence of systematic error, the reflection coefficient obtained by Network Analyzer measurement
with
between there is certain difference, can by updating formula below:
， （4）
Try to achieve
, wherein,
,
,
correspond to the directional error of measuring system, source matching error and frequency response error three systematic errors respectively, this systematic error can adopt open circuit, short circuit, titer carrying method to eliminate respectively.In conjunction with (2), (3), (4) three formula, after adopting open circuit, short circuit, titer carrying method to measure, can be eliminated by computing
with
, finally try to achieve
, also namely obtain tested sample relative permitivity and electrical conductivity relative value.
Rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit.
Probe unit detection is imitated the rf electric field value of organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to rf electric field signal transmission unit, power supply signal is delivered to rf electric field equivalence value measuring unit by rf electric field signal transmission unit, and rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site.
Concrete, probe unit is provided with sensor, and rf electric field signal transmission unit is provided with analog-digital converter, and the outfan of sensor is connected with the input of analog-digital converter, and the outfan of analog-digital converter is connected with the input of rf electric field signal transmission unit.
The operating frequency range of sensor is identical with magnetic resonance system operating frequency range, and (7T magnetic resonance system corresponds to 298MH
z, 3T magnetic resonance system corresponds to 128MH
z).As shown in Figure 2, sensor is dipole antenna configuration, the respective length L of dipole both arms 100 is set to 10mm, gap H between dipole both arms 100 is set to 2mm, gap H between dipole both arms 100 is provided with Schottky diode D, by the time humorous electric field at mm place, gap 2 can produce at the two ends detecting Schottky diode D with time humorous electric field magnitude square proportional DC voltage.Dipole, both arms were connected to the input of analog-digital converter by high impedance wire, were drawn by DC voltage to be delivered to analog-digital converter and to carry out analog digital conversion, then inputed to the equivalence value that rf electric field equivalence value measuring unit calculates the rf electric field obtaining target site.
Dipole, is set to Copper Foil.High impedance wire is made up of the wire being provided with resistance R, and resistance R is set to 50 ohm usually, and certainly, resistance R can be arranged according to actual needs flexibly.Electric capacity C is connected with, to input stable magnitude of voltage to analog-digital converter between dipole both arms outfan.
Computing module installation has collecting unit, computing unit and result output unit.The input of collecting unit is connected with the outfan of rf electric field equivalence value measuring unit, and the outfan of collecting unit is connected with the input of computing unit.Computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency Local SAR value,
High-field magnetic resonance scanning security test body mould system of the present invention, the Local SAR value that can provide magnetic resonance system verifies, and guarantees the safety of magnetic resonance scan sequences.Its principle is: when carrying out high-field magnetic resonance scanning, this system is placed in the scanning area of magnetic resonance system, the magnetic resonance imaging radio frequency Local SAR1 value obtaining target site is calculated by high-field magnetic resonance scanning security test body mould system, pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that this imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified.The Local SAR value that the present invention can provide magnetic resonance system verifies, thus ensures the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
High-field magnetic resonance scanning security test body mould system of the present invention, adopt the imitative organisms mould of simulation human body different parts, can be measured the equivalence value of the rf electric field of any part in imitative organisms mould by probe unit, thus the Local SAR value of any part in imitative organisms mould is detected and verified.Owing to adopting imitative organisms mould, therefore can for different individuals scanned previously prepared imitative organisms mould akin with its dielectricity, thus the accuracy in scanning process can be guaranteed, guarantee the safety of magnetic resonance imaging.
The invention solves the defect of the Local SAR value that accurately can not judge magnetic resonance system in prior art, have result accurate, simple to operate, feature easy to use, can guarantee the use safety of magnetic resonance system.
embodiment 2.
A kind of high-field magnetic resonance scanning security test body mould system, other structure is identical with embodiment 1, and difference is: computing module is also provided with display unit, and display unit is connected with the outfan of result output unit.Result can be shown by display unit, easy to use.
embodiment 3.
A kind of high-field magnetic resonance scanning security test body mould system, other structure is identical with embodiment 1, and difference is: the rf electric field equivalence value measuring unit in the present embodiment is integrated in computing module, flexible form.
embodiment 4.
A kind of high-field magnetic resonance scanning method for testing security, adopts above-mentioned high-field magnetic resonance to scan security test body mould system and tests, comprise the steps.
A, previously prepared imitative organisms mould, imitative organisms mould is provided with the cavity of simulation human anatomic structure, bionical fabric texture dielectric material is filled with in cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in cavity, different parts is filled and the electromagnetic parameter of the corresponding site of tissue match, and make the electromagnetic parameter of the bionical electromagnetic parameter of fabric texture dielectric material and the corresponding position of tissue as far as possible close.
The dielectric material that imitative organisms mold cavity is arranged can be the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous, is mixed to form different dielectric constant and electrical conductivity by different proportion.Body mould dielectric material can also adopt the aqueous gelatin oil mixture of salt adding.Oil can adopt vegetable oil, and the oil of different content can simulate the tissue of different moisture content, comprises high-moisture tissue if muscle, tumor and low water content tissue are as fat, bone marrow etc., salt content number can change the size of electrical conductivity.Such as, be simulated muscle tissue phantom, the aqueous gelatin of 90% can be adopted, the vegetable oil of mixing 10%, then add salt (NaCl) according to the ratio of every 1000ml solution 6 grams; For simulated fat tissue, the aqueous gelatin of 15% can be adopted, the vegetable oil of mixing 85%, then add salt according to the ratio of every 1000ml solution 0.24 gram.
For the final mixture dielectric material formed, Network Analyzer can be used, adopt coaxial probe measuring method, measure its electrical conductivity and dielectric constant accurately, make the electromagnetic dielectric such as electrical conductivity and dielectric constant parameter as far as possible close with corresponding biological tissue's electromagnetic parameter.During measurement, measure the reflection coefficient at sample and coaxial cable interface
for:
， （2）
Wherein
for the characteristic impedance of coaxial line, be generally 50 Ω,
for the complex impedance of sample, jointly determined by the electrical conductivity of sample and dielectric constant, be generally:
, （3）
Here,
correspond to the resonant frequency of MRI system,
be multiple relative dielectric constant, its real part correspond to relative permitivity, and imaginary part correspond to electrical conductivity relative value.Due to the existence of systematic error, the reflection coefficient obtained by Network Analyzer measurement
with
between there is certain difference, can by updating formula below:
， （4）
Try to achieve
, wherein,
,
,
correspond to the directional error of measuring system, source matching error and frequency response error three systematic errors respectively, this systematic error can adopt open circuit, short circuit, titer carrying method to eliminate respectively.In conjunction with (2), (3), (4) three formula, after adopting open circuit, short circuit, titer carrying method to measure, can be eliminated by computing
with
, finally try to achieve
, also namely obtain tested sample relative permitivity and electrical conductivity relative value.
B, then, imitative organisms mould is placed at the working region of magnetic resonance system, rf electric field measurement module is measured the rf electric field of the target site of imitative organisms mould and is obtained the rf electric field equivalence value of target site, the dielectric parameter at the rf electric field equivalence value that processing module obtains according to rf electric field measurement module and bionical object body mould system test position, calculates the magnetic resonance imaging radio frequency Local SAR value of target site.
Rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit.
Probe unit detection is imitated the rf electric field value of organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to described rf electric field signal transmission unit, power supply signal is delivered to rf electric field equivalence value measuring unit by rf electric field signal transmission unit, and rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site.
Probe unit is provided with sensor, and rf electric field signal transmission unit is provided with analog-digital converter, and the outfan of sensor is connected with the input of analog-digital converter, and the outfan of analog-digital converter is connected with the input of described rf electric field signal transmission unit.
Sensor is dipole antenna configuration, dipole both arms separately length L be set to 10mm, gap H between described dipole both arms is set to 2mm, is provided with Schottky diode D between dipole both arms, dipole both arms be connected to the input of analog-digital converter by high impedance wire.
Dipole, is set to Copper Foil.High impedance wire is made up of the wire being provided with resistance R, and resistance R is set to 50 ohm usually, and certainly, resistance R can be arranged according to actual needs flexibly.Electric capacity C is connected with, to input stable magnitude of voltage to analog-digital converter between dipole both arms outfan.
Computing module installation has collecting unit, computing unit and result output unit.
The input of collecting unit is connected with the outfan of described rf electric field equivalence value measuring unit, and the outfan of collecting unit is connected with the input of computing unit.
Computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency SAR value.
Specifically, the power supply signal at sensor detection of a target position, carries out after analog digital conversion through analog-digital converter step b, is delivered to rf electric field equivalence value measuring unit, is measured the rf electric field equivalence value obtaining target site by rf electric field equivalence value measuring unit.
Measured rf electric field equivalence value is delivered to the collecting unit of computing module installation by rf electric field equivalence value measuring unit; The dielectric parameter at the rf electric field equivalence value that computing unit obtains according to described rf electric field measurement module and described bionical object body mould system aims of systems position, calculates the magnetic resonance imaging radio frequency Local SAR value of target site according to formula (1) computing unit,
High-field magnetic resonance scanning method for testing security provided by the invention, high-field magnetic resonance scanning security test body mould system is adopted to test, imitative organisms mould is placed at the working region of magnetic resonance system, measured the rf electric field of the target site of imitative organisms mould by rf electric field measurement module and obtain the rf electric field equivalence value of target site, and calculating the magnetic resonance imaging radio frequency Local SAR value of target site.Pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified, thus ensure the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
embodiment 5.
A kind of magnetic resonance system, has the high-field magnetic resonance scanning security test body mould system as embodiment 1 to 3 any one.When carrying out high-field magnetic resonance scanning, the magnetic resonance imaging radio frequency Local SAR1 value obtaining target site is calculated by high-field magnetic resonance scanning security test body mould system, pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that described imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified, thus ensure the safety of magnetic resonance imaging, and the present invention can the Local SAR value of noinvasive to different parts verify.
Finally should be noted that; above embodiment is only in order to illustrate technical scheme of the present invention but not limiting the scope of the invention; although be explained in detail the present invention with reference to preferred embodiment; those of ordinary skill in the art is to be understood that; can modify to technical scheme of the present invention or equivalent replacement, and not depart from essence and the scope of technical solution of the present invention.
Claims (8)
1. high-field magnetic resonance scanning security test body mould system, is characterized in that: be provided with rf electric field measurement module, imitative organisms mould and computing module;
Described imitative organisms mould is placed in the working region of magnetic resonance system, the rf electric field of the target site of the described imitative organisms mould of described rf electric field measurement module detection also obtains the rf electric field equivalence value of target site, the dielectric parameter of the rf electric field equivalence value that described processing module obtains according to described rf electric field measurement module and described bionical object body mould system target site, calculates the magnetic resonance imaging radio frequency Local SAR value obtaining target site;
Described rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit;
Described probe unit detects the rf electric field value of described imitative organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to described rf electric field signal transmission unit, described power supply signal is delivered to described rf electric field equivalence value measuring unit by described rf electric field signal transmission unit, and described rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site;
Described probe unit is provided with sensor, described rf electric field signal transmission unit is provided with analog-digital converter, the outfan of described sensor is connected with the input of described analog-digital converter, and the outfan of described analog-digital converter is connected with the input of described rf electric field signal transmission unit;
Described sensor is dipole antenna configuration, described dipole both arms separately length L be set to 10mm, gap H between described dipole both arms is set to 2mm, be provided with Schottky diode D between described dipole both arms, described dipole both arms be connected to the input of described analog-digital converter by high impedance wire.
2. high-field magnetic resonance scanning security test body mould system according to claim 1, is characterized in that: described computing module installation has collecting unit, computing unit and result output unit;
The input of described collecting unit is connected with the outfan of described rf electric field equivalence value measuring unit, and the outfan of described collecting unit is connected with the input of described computing unit;
Described computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency Local SAR value;
。
3. high-field magnetic resonance scanning security test body mould system according to claim 2, it is characterized in that: described computing module is also provided with display unit, described display unit is connected with the outfan of described result output unit.
4. high-field magnetic resonance scanning security test body mould system according to claim 3, it is characterized in that: described imitative organisms mould is provided with the cavity of simulation human anatomic structure, be filled with bionical fabric texture dielectric material in described cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in described cavity, different parts is filled and the electromagnetic parameter of the corresponding position of tissue match.
5. high-field magnetic resonance scanning security test body mould system according to claim 4, is characterized in that: described dielectric material is the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous.
6. a high-field magnetic resonance scanning method for testing security, adopts high-field magnetic resonance as claimed in claim 1 to scan security test body mould system and tests, it is characterized in that:
Comprise the steps,
A, previously prepared imitative organisms mould, described imitative organisms mould is provided with the cavity of simulation human anatomic structure, be filled with bionical fabric texture dielectric material in described cavity, the bionical electromagnetic parameter of fabric texture dielectric material that in described cavity, different parts is filled and the electromagnetic parameter of the corresponding site of tissue match; Described dielectric material is the mixture of the mixed solution of water and two propanol or the aqueous gelatin oil for saliferous; To the mixture dielectric material of the imitative organisms mould of final preparation, use Network Analyzer to adopt coaxial detection method to measure its electrical conductivity and dielectric constant, electromagnetic dielectric parameter is matched with corresponding biological tissue's electromagnetic parameter;
B, described imitative organisms mould are placed at the working region of magnetic resonance system, described rf electric field measurement module is measured the rf electric field of the target site of imitative organisms mould and is obtained the rf electric field equivalence value of target site, the dielectric parameter at the rf electric field equivalence value that described processing module obtains according to described rf electric field measurement module and described bionical object body mould system test position, calculates the magnetic resonance imaging radio frequency Local SAR value of target site.
7. high-field magnetic resonance scanning method for testing security according to claim 6, is characterized in that:
Described rf electric field measurement module is provided with probe unit, rf electric field signal transmission unit and rf electric field equivalence value measuring unit;
Described probe unit detects the rf electric field value of described imitative organisms mould target site and converts rf electric field value to measurable power supply signal, be delivered to described rf electric field signal transmission unit, described power supply signal is delivered to described rf electric field equivalence value measuring unit by described rf electric field signal transmission unit, and described rf electric field equivalence value measuring unit measures the equivalence value of the rf electric field obtaining target site;
Described probe unit is provided with sensor, described rf electric field signal transmission unit is provided with analog-digital converter, the outfan of described sensor is connected with the input of described analog-digital converter, and the outfan of described analog-digital converter is connected with the input of described rf electric field signal transmission unit;
Described sensor is dipole antenna configuration, described dipole both arms separately length L be set to 10mm, gap H between described dipole both arms is set to 2mm, be provided with Schottky diode D between described dipole both arms, described dipole both arms be connected to the input of described analog-digital converter by high impedance wire;
Described computing module installation has collecting unit, computing unit and result output unit;
The input of described collecting unit is connected with the outfan of described rf electric field equivalence value measuring unit, and the outfan of described collecting unit is connected with the input of described computing unit;
Described computing unit, according to the dielectric parameter at rf electric field equivalence value combining target position, completes and calculates target site magnetic resonance imaging radio frequency SAR value;
Described step b specifically, the power supply signal at described sensor detection of a target position, carry out after analog digital conversion through analog-digital converter, be delivered to rf electric field equivalence value measuring unit, measured the rf electric field equivalence value obtaining target site by rf electric field equivalence value measuring unit;
Measured rf electric field equivalence value is delivered to the collecting unit of computing module installation by rf electric field equivalence value measuring unit;
。
8. a magnetic resonance system, it is characterized in that: be provided with the high-field magnetic resonance scanning security test body mould system as described in claim 1 to 5 any one, when carrying out high-field magnetic resonance scanning, the magnetic resonance imaging radio frequency Local SAR1 value obtaining target site is calculated by high-field magnetic resonance scanning security test body mould system, pass through the magnetic resonance imaging radio frequency Local SAR1 value of obtained target site and magnetic resonance system to scan the Local SAR2 value that described imitative organisms mould obtains automatically and compare, the Local SAR2 value that magnetic resonance system provides is verified.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107137083A (en) * | 2017-06-16 | 2017-09-08 | 上海联影医疗科技有限公司 | A kind of magnetic resonance scanning method, system and computer-readable recording medium |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105974208B (en) * | 2016-05-10 | 2019-02-12 | 上海理工大学 | The measuring system of specific absorption rate under Nuclear Magnetic Resonance |
| CN107144805A (en) * | 2017-06-09 | 2017-09-08 | 创领心律管理医疗器械（上海）有限公司 | A kind of synthesis field method of testing of lower limb model and magnetic resonance imaging safety evaluation |
| CN113017598B (en) * | 2021-03-11 | 2023-11-21 | 中国科学院深圳先进技术研究院 | Radio frequency energy deposition prediction and monitoring method, device, equipment and medium |
| CN114191709A (en) * | 2021-12-17 | 2022-03-18 | 兰州大学 | Implanted medical equipment electromagnetic model transfer function verification system and method based on four-way parallel transmission |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102568287A (en) * | 2010-12-24 | 2012-07-11 | 中国科学院深圳先进技术研究院 | Multimodality bionic body model |
-
2013
- 2013-06-02 CN CN201310212935.1A patent/CN103284723B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102568287A (en) * | 2010-12-24 | 2012-07-11 | 中国科学院深圳先进技术研究院 | Multimodality bionic body model |
Non-Patent Citations (2)
| Title |
|---|
| Determination of Electric Conductivity and Local SAR Via B1 Mapping;Ulrich Katscher et al;《IEEE TRANSACTIONS ON MEDICAL IMAGING》;20090930;第28卷(第9期);摘要、第II-VI部分、附图1 * |
| MR射频能量特定吸收率在女性盆腔不同组织中分布规律的研究;曾雁冰等;《中国医学物理学杂志》;20120930;第29卷(第5期);第3632-3637页 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107137083A (en) * | 2017-06-16 | 2017-09-08 | 上海联影医疗科技有限公司 | A kind of magnetic resonance scanning method, system and computer-readable recording medium |
| CN107137083B (en) * | 2017-06-16 | 2020-05-15 | 上海联影医疗科技有限公司 | Magnetic resonance scanning method, system and computer readable storage medium |
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