JPH08238225A - Calibration method for organic magnetism measuring apparatus - Google Patents
Calibration method for organic magnetism measuring apparatusInfo
- Publication number
- JPH08238225A JPH08238225A JP7074415A JP7441595A JPH08238225A JP H08238225 A JPH08238225 A JP H08238225A JP 7074415 A JP7074415 A JP 7074415A JP 7441595 A JP7441595 A JP 7441595A JP H08238225 A JPH08238225 A JP H08238225A
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- Prior art keywords
- coil
- calibration
- detection
- squid
- sensor
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- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、生体から発生する微
小な磁気を検出することにより、生体活動電流源の位
置，向き，大きさを推定する生体磁気計測装置の較正
（キャリブレーション）方法に係り、特に、磁気検出用
のマルチチャンネルＳＱＵＩＤセンサを構成する各ＳＱ
ＵＩＤセンサの位置，方向および磁束／電圧変換係数を
測定する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating a biomagnetism measuring device for estimating the position, orientation and size of a bioactive current source by detecting minute magnetism generated from a living body. In particular, each SQ forming a multi-channel SQUID sensor for magnetic detection
The present invention relates to a method for measuring the position, orientation and magnetic flux / voltage conversion coefficient of a UID sensor.
【０００２】[0002]
【従来の技術】生体に対して光や音のような外界の刺激
を与えると、感覚神経に信号（生体活動電流）が発生す
る。この生体活動電流によって形成される磁界を、ＳＱ
ＵＩＤ（Superconducting Quantum Interface Device:
超電導量子干渉計）を用いたセンサで計測し、その計測
データから生体活動電流源（以下、単に電流源という）
の位置，大きさ，方向を推定する。推定された電流源
は、Ｘ線ＣＴ装置やＭＲＩ層などで撮像された体内断層
像上に表示され、患部等の物理的位置の特定などに利用
される。2. Description of the Related Art When an external stimulus such as light or sound is given to a living body, a signal (biologically active current) is generated in a sensory nerve. The magnetic field formed by this biological activity current is SQ
UID (Superconducting Quantum Interface Device:
A sensor that uses a superconducting quantum interferometer) is used to measure, and from the measured data, a biological activity current source (hereinafter simply referred to as a current source)
Estimate the position, size, and direction of. The estimated current source is displayed on an in-vivo tomographic image captured by an X-ray CT apparatus, an MRI layer, or the like, and is used for specifying the physical position of the affected area or the like.
【０００３】断層像上に電流源を正確に表示するために
は、まず、ＳＱＵＩＤセンサの測定点と生体との位置関
係を正確に求めておく必要がある。ＳＱＵＩＤセンサ
は、デュワーと呼ばれる冷媒容器内にＳＱＵＩＤ素子と
検出コイルおよび補償コイルとを収納して構成されてお
り、ＳＱＵＩＤ素子の超伝導状態を維持するために、デ
ュワー内部は液体ヘリウムなどの冷媒で満たされてい
る。前記ＳＱＵＩＤセンサの測定点とは、デュワーに収
納された検出／補償コイルの位置および方向をいう。In order to accurately display the current source on the tomographic image, it is first necessary to accurately determine the positional relationship between the measurement point of the SQUID sensor and the living body. The SQUID sensor is configured by accommodating a SQUID element, a detection coil, and a compensation coil in a refrigerant container called a dewar. In order to maintain the superconducting state of the SQUID element, the inside of the dewar is made of a refrigerant such as liquid helium. be satisfied. The measurement point of the SQUID sensor refers to the position and direction of the detection / compensation coil housed in the dewar.
【０００４】また、ＳＱＵＩＤセンサは、生体活動電流
源によって生じる磁界を電圧信号に変換して出力するも
のであるので、ＳＱＵＩＤセンサの磁界／電圧変換係数
を正確に求めておくことも、電流源を正しく推定する上
で重要である。Further, since the SQUID sensor converts the magnetic field generated by the biological activity current source into a voltage signal and outputs the voltage signal, the magnetic field / voltage conversion coefficient of the SQUID sensor can be accurately obtained by using the current source. It is important to make a correct estimation.
【０００５】以下に、ＳＱＵＩＤセンサの測定点と生体
との位置関係を求める従来手法と、ＳＱＵＩＤセンサの
磁界／電圧変換係数を求める従来手法を説明する。The conventional method for obtaining the positional relationship between the measurement point of the SQUID sensor and the living body and the conventional method for obtaining the magnetic field / voltage conversion coefficient of the SQUID sensor will be described below.
【０００６】ＳＱＵＩＤセンサの測定点となる前記検出
／補償コイルの位置および方向と、生体との位置関係を
求めるには、まず、デュワーを基準とした３次元座標系
に対する検出／補償コイルの位置，方向を設計図を参照
して把握しておく。次に、デュワーに投光器を取り付け
て光ビームを生体に照射して、デュワーの座標系に対す
る生体の位置関係を把握する。これらの情報、すなわ
ち、デュワーと検出／補償コイルの位置，方向との関
係、およびデュワーと生体との位置関係から、検出／補
償コイルの位置，方向と生体との位置関係を求めてい
る。In order to obtain the positional relationship between the position and direction of the detection / compensation coil, which is the measurement point of the SQUID sensor, and the living body, first, the position of the detection / compensation coil with respect to the three-dimensional coordinate system with Dewar as a reference, Know the direction by referring to the blueprint. Next, a light projector is attached to the dewar to irradiate the living body with a light beam, and the positional relationship of the living body with respect to the dewar coordinate system is grasped. The positional relationship between the detection / compensation coil and the living body is obtained from these pieces of information, that is, the relationship between the dewar and the position / direction of the detection / compensation coil, and the positional relationship between the dewar and the living body.
【０００７】ところが、検出／補償コイルがデュワー内
の冷媒に浸漬されて極低温状態下にあるので、検出／補
償コイルが収縮してしまい、実用上において設計図通り
の位置，方向に保たれておらず、デュワーと検出コイル
の位置，方向との関係を正確に把握することができな
い。また、検出／補償コイルの製作誤差やデュワーへの
取り付け誤差などによっても同様の問題が起こる。However, since the detection / compensation coil is immersed in the refrigerant in the dewar and is in an extremely low temperature state, the detection / compensation coil contracts and is practically kept in the position and direction as designed. Therefore, the relationship between the dewar and the position and direction of the detection coil cannot be accurately grasped. The same problem also occurs due to manufacturing error of the detection / compensation coil and mounting error to the dewar.
【０００８】そこで、本出願人は、上記の問題を解決す
るために、デュワーに収納されている検出／補償コイル
を複数方向からＸ線撮影し、そのＸ線像から検出／補償
コイルの位置，方向を測定する手法を提案している（特
開平５−１１９１３６号公報）。この手法によれば、デ
ュワー内の冷媒中に検出／補償コイルを浸漬した状態で
検出／補償コイルの位置，方向を測定することができる
ので、冷媒による検出／補償コイルの収縮や、検出／補
償コイルの製作誤差や取り付け誤差などに関係なく、検
出／補償コイルの位置，方向を正確に測定することがで
きる。Therefore, in order to solve the above-mentioned problem, the present applicant takes X-ray images of the detection / compensation coils housed in the dewar from a plurality of directions, and detects the positions of the detection / compensation coils from the X-ray images. A method for measuring the direction has been proposed (Japanese Patent Laid-Open No. 5-119136). According to this method, the position / direction of the detection / compensation coil can be measured while the detection / compensation coil is immersed in the refrigerant in the dewar, so that the detection / compensation coil contracts due to the refrigerant, and the detection / compensation coil contracts. The position and direction of the detection / compensation coil can be accurately measured regardless of the manufacturing error and mounting error of the coil.
【０００９】一方、ＳＱＵＩＤセンサの磁束／電圧変換
係数は、ＳＱＵＩＤセンサをデュワー内に収納する前
に、そのＳＱＵＩＤセンサを既知の一様磁場の中に置い
て、その出力電圧を冷媒中で測定することにより求めら
れる。On the other hand, the magnetic flux / voltage conversion coefficient of the SQUID sensor is measured by placing the SQUID sensor in a known uniform magnetic field and storing the output voltage in the refrigerant before housing the SQUID sensor in the dewar. Required by
【００１０】[0010]
【発明が解決しようとする課題】しかしながら、このよ
うな構成を有する従来例の場合には、次のような問題が
ある。最近では、多数個のＳＱＵＩＤセンサを３次元配
置してデュワー内に収納したマルチチャンネルＳＱＵＩ
Ｄセンサが提案実施されているが、このようなマルチチ
ャンネルＳＱＵＩＤセンサの各測定点（各検出／補償コ
イルの位置および方向）を上記特開平５−１１９１３６
号公報で開示された手法で測定した場合、各ＳＱＵＩＤ
センサが重なり合ってＸ線撮影されるので、各ＳＱＵＩ
Ｄセンサの位置や方向を正しく認識することができな
い。However, the prior art having such a structure has the following problems. Recently, a multi-channel SQUI with a large number of SQUID sensors arranged three-dimensionally and housed in a dewar
Although a D sensor has been proposed and implemented, each measurement point (position and direction of each detection / compensation coil) of such a multi-channel SQUID sensor is described in the above-mentioned JP-A-5-119136.
Each SQUID when measured by the method disclosed in the publication
Since X-rays are taken with the sensors overlapping each other, each SQUI
The position and direction of the D sensor cannot be correctly recognized.
【００１１】また、デュワーに収納する前に多数個のＳ
ＱＵＩＤセンサの磁束／電圧変換係数をそれぞれ個別に
測定するのは非常に煩雑である。In addition, before storing in the dewar, a large number of S
It is very complicated to individually measure the magnetic flux / voltage conversion coefficient of the QUID sensor.
【００１２】この発明は、このような事情に鑑みてなさ
れたものであって、マルチチャンネルＳＱＵＩＤセンサ
を構成する各ＳＱＵＩＤセンサの位置，方向および磁束
／電圧変換係数を容易かつ正確に測定することができる
生体磁気計測装置の較正方法を提供することを目的とす
る。The present invention has been made in view of such circumstances, and it is possible to easily and accurately measure the position, direction, and magnetic flux / voltage conversion coefficient of each SQUID sensor that constitutes a multi-channel SQUID sensor. An object of the present invention is to provide a method of calibrating a biomagnetism measuring device that can be used.
【００１３】[0013]
【課題を解決するための手段】この発明は、このような
目的を達成するために、次のような構成をとる。すなわ
ち、この発明は、検出コイルと補償コイル、およびこれ
らコイルに接続されたＳＱＵＩＤ素子で構成されたＳＱ
ＵＩＤセンサを３次元配置して冷媒容器内に収納したマ
ルチチャンネルＳＱＵＩＤセンサの各ＳＱＵＩＤセンサ
の検出／補償コイルの位置，方向および磁束／電圧変換
係数を測定する、生体磁気計測装置の較正方法であっ
て、（ａ）予め知られた複数箇所の位置に予め知られた
方向に較正用コイルを配置し、各箇所で較正用コイルに
既知電流を順に流して磁場を生成する過程と、（ｂ）前
記各箇所で較正用コイルによって生成された磁場を任意
の位置にセットされた各ＳＱＵＩＤセンサで検出して、
それぞれの測定電圧値を得る過程と、（ｃ）前記較正用
コイルを前記各箇所に同様に配置して同じ既知電流を流
したと仮定した場合に、前記各ＳＱＵＩＤセンサで検出
されるべき各出力電圧（仮定電圧値）を、前記各ＳＱＵ
ＩＤセンサの検出／補償コイルの位置，方向および磁束
／電圧変換係数からなる未知のパラメータ群を使って表
し、前記仮定電圧値が前記測定電圧値に最も近い値にな
るように、前記未知のパラメータ群を最適化することに
より、各ＳＱＵＩＤセンサの検出／補償コイルの位置，
方向および磁束／電圧変換係数を求める過程と、を備え
たことを特徴とする。The present invention has the following configuration to achieve the above object. That is, the present invention is an SQ including a detection coil, a compensation coil, and an SQUID element connected to these coils.
A calibration method for a biomagnetism measuring device which measures the position and direction of the detection / compensation coil and the magnetic flux / voltage conversion coefficient of each SQUID sensor of a multi-channel SQUID sensor in which UID sensors are three-dimensionally arranged and housed in a refrigerant container. And (a) a step of arranging a calibration coil in a known direction at a plurality of known positions and generating a magnetic field by sequentially passing a known current through the calibration coil at each position, and (b) The magnetic field generated by the calibration coil at each location is detected by each SQUID sensor set at an arbitrary position,
Steps of obtaining respective measured voltage values, and (c) each output to be detected by each SQUID sensor, assuming that the calibration coils are similarly arranged at the respective locations and the same known current is applied. The voltage (assumed voltage value) is calculated by
An unknown parameter group consisting of the position and direction of the detection / compensation coil of the ID sensor and the magnetic flux / voltage conversion coefficient is used to represent the unknown parameter so that the assumed voltage value is the closest to the measured voltage value. By optimizing the group, the position of the detection / compensation coil of each SQUID sensor,
And a step of obtaining a direction and a magnetic flux / voltage conversion coefficient.
【００１４】[0014]
【作用】この発明の作用は次のとおりである。予め知ら
れた位置および方向に較正用コイルを配置し、その較正
用コイルに既知電流を流して磁場を生成すると、その較
正用コイルが置かれた空間内の各位置における磁場ベク
トルは確定するので、これを計算によって求めることが
できる。したがって、各ＳＱＵＩＤセンサの検出／補償
コイルの位置，方向および磁束／電圧変換係数を測定す
るにあたり、予め知られた位置および方向に較正用コイ
ルを順に配置して、その較正用コイルに既知電流を流し
て磁場を生成し、そのときの各ＳＱＵＩＤセンサの出力
電圧を測定し、その測定電圧値と上記の計算上求められ
る磁場ベクトルに起因する各ＳＱＵＩＤセンサの出力電
圧（仮定電圧値）とを比較することにより、各ＳＱＵＩ
Ｄセンサの検出／補償コイルの位置，方向および磁束／
電圧変換係数を逆算することができる。つまり、前記仮
定電圧値は各ＳＱＵＩＤセンサの検出／補償コイルの位
置，方向および磁束／電圧変換係数を未知のパラメータ
として含むので、前記仮定電圧が測定電圧と最も近い値
をもつように各パラメータを最適化すれば、各ＳＱＵＩ
Ｄセンサの検出／補償コイルの位置，方向および磁束／
電圧変換係数を知ることができる。The operation of the present invention is as follows. When the calibration coil is arranged at a known position and direction and a known current is applied to the calibration coil to generate a magnetic field, the magnetic field vector at each position in the space where the calibration coil is placed is determined. , Which can be calculated. Therefore, when measuring the position / direction and the magnetic flux / voltage conversion coefficient of the detection / compensation coil of each SQUID sensor, the calibration coil is sequentially arranged at a known position and direction, and a known current is applied to the calibration coil. Generate a magnetic field by flowing it, measure the output voltage of each SQUID sensor at that time, and compare the measured voltage value with the output voltage (assumed voltage value) of each SQUID sensor resulting from the magnetic field vector calculated above. Each SQUI
D sensor detection / compensation coil position, direction and magnetic flux /
The voltage conversion factor can be calculated back. That is, since the assumed voltage value includes the position and direction of the detection / compensation coil of each SQUID sensor and the magnetic flux / voltage conversion coefficient as unknown parameters, each parameter is set so that the assumed voltage has a value closest to the measured voltage. If optimized, each SQUI
D sensor detection / compensation coil position, direction and magnetic flux /
You can know the voltage conversion coefficient.
【００１５】[0015]
【実施例】以下、図面を参照してこの発明の一実施例を
説明する。図１は生体磁気計測装置の較正方法の一例を
示す概略図である。図中、符号１は生体磁気計測装置に
備えられたマルチチャンネルＳＱＵＩＤセンサである。
マルチチャンネルＳＱＵＩＤセンサ１は、冷媒容器（以
下、デュワーと言う）２内に、例えば数１０チャンネル
のＳＱＵＩＤセンサ３を３次元配置し、液体ヘリウム等
の冷媒に浸漬して構成されている。本実施例で用いられ
るＳＱＵＩＤセンサ３は、軸型１次微分型ＳＱＵＩＤセ
ンサと呼ばれるもので、図２に示すように、同軸状に配
置されて差動接続された検出コイル４と補償コイル５、
およびこれらの検出／補償コイル４，５に接続された図
示しないＳＱＵＩＤ素子とから構成されている。本実施
例方法では、図３に示すように、上述した各ＳＱＵＩＤ
センサ３の検出コイル４の中心Ｄの位置（ｘdi，ｙdi，
ｚdi）と、補償コイル５の中心Ｃの位置（ｘci，ｙci，
ｚci）と、検出コイル４の方向（コイル面の法線方向）
（θdi，ψdi）と、補償コイル５の方向（θci，ψci）
とを測定するとともに、検出／補償コイル４，５で検出
された磁場強度とＳＱＵＩＤ素子の出力電圧との関係を
示す磁束／電圧変換係数ｋi を測定することになる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a calibration method for a biomagnetism measuring device. In the figure, reference numeral 1 is a multi-channel SQUID sensor provided in the biomagnetism measuring device.
The multi-channel SQUID sensor 1 is configured by three-dimensionally arranging, for example, several tens of channels of SQUID sensors 3 in a refrigerant container (hereinafter referred to as Dewar) 2 and immersing it in a refrigerant such as liquid helium. The SQUID sensor 3 used in this embodiment is called an axial first-order differential type SQUID sensor, and as shown in FIG. 2, the detection coil 4 and the compensation coil 5, which are coaxially arranged and differentially connected,
And a SQUID element (not shown) connected to these detection / compensation coils 4 and 5. In the method of this embodiment, as shown in FIG. 3, each SQUID described above is used.
The position of the center D of the detection coil 4 of the sensor 3 (x di , y di ,
z di ) and the position of the center C of the compensation coil 5 (x ci , y ci ,
z ci ) and the direction of the detection coil 4 (direction normal to the coil surface)
(Θ di , ψ di ) and the direction of the compensation coil 5 (θ ci , ψ ci ).
And the magnetic flux / voltage conversion coefficient k i indicating the relationship between the magnetic field strength detected by the detection / compensation coils 4 and 5 and the output voltage of the SQUID element.
【００１６】なお、この発明方法が適用可能なＳＱＵＩ
Ｄセンサは、上述した軸型１次微分型ＳＱＵＩＤセンサ
に限らず、検出コイルと補償コイルとが平面上に配置さ
れた平面型のＳＱＵＩＤセンサや、２次微分型のＳＱＵ
ＩＤセンサ、あるいは検出コイルのみで構成されたもの
（マグネトメータ）など、種々のＳＱＵＩＤセンサの検
出／補償コイルの位置，方向および磁束／電圧変換係数
の測定に適用することができる。The SQUI to which the method of the present invention is applicable
The D sensor is not limited to the axial first-order differential type SQUID sensor described above, but is also a flat-type SQUID sensor in which a detection coil and a compensation coil are arranged on a plane, and a second-order differential type SQUID.
The present invention can be applied to the measurement of the position and direction of the detection / compensation coil and the magnetic flux / voltage conversion coefficient of various SQUID sensors such as an ID sensor or a sensor (magnetometer) composed of only a detection coil.
【００１７】図１中の符号１０は、上述した各ＳＱＵＩ
Ｄセンサ３の検出／補償コイル４，５の位置，方向およ
び磁束／電圧変換係数の測定に使用される較正用装置で
ある。この較正用装置１０は、基台１１上に所定のピッ
チで２次元配置された較正用コイル１２群と、各較正用
コイル１２に順に所定の電流を流す選択駆動部１３とか
ら構成されている。図４に示すように、較正用コイル１
２は、立方体状のブロックに薄膜コイル１２x ，１
２y ，１２z を貼り付けて構成されている。これらの薄
膜コイル１２x ，１２y ，１２z は選択駆動部１３によ
って個別に駆動される。Reference numeral 10 in FIG. 1 is each SQUI described above.
This is a calibration device used for measuring the positions and directions of the detection / compensation coils 4 and 5 of the D sensor 3 and the magnetic flux / voltage conversion coefficient. The calibration device 10 is composed of a group of calibration coils 12 two-dimensionally arranged on a base 11 at a predetermined pitch, and a selection drive unit 13 that sequentially applies a predetermined current to each of the calibration coils 12. . As shown in FIG. 4, the calibration coil 1
2 is a thin film coil 12 x , 1 in a cubic block
It is configured by pasting 2 y and 12 z . These thin film coils 12 x , 12 y and 12 z are individually driven by the selection drive unit 13.
【００１８】なお、本実施例において、各較正用コイル
１２を３個の薄膜コイル１２x ，１２y ，１２z で構成
したのは、較正用コイル１２の各設置箇所で種々の方向
に磁場を発生させることによって、上述した検出／補償
コイル４，５の位置，方向および磁束／電圧変換係数の
測定精度を出来るだけ上げるためである。したがって、
精度上特に問題がなければ、各較正用コイル１２をそれ
ぞれ一つのコイルで構成してもよい。また、各較正用コ
イル１２は必ずしも所定のピッチ、あるいは方向に配置
されている必要はない。要するに、各較正用コイル１２
の設置された位置および方向が既知であればよい。In the present embodiment, each calibration coil 12 is composed of three thin film coils 12 x , 12 y , and 12 z because the magnetic field is applied in various directions at each installation location of the calibration coil 12. This is to increase the accuracy of the measurement of the positions and directions of the detection / compensation coils 4 and 5 and the magnetic flux / voltage conversion coefficient as much as possible. Therefore,
If there is no particular problem in terms of accuracy, each calibration coil 12 may be composed of one coil. Further, the calibration coils 12 do not necessarily have to be arranged at a predetermined pitch or direction. In short, each calibration coil 12
It suffices that the installed position and direction of the are known.
【００１９】以下、本実施例に係る較正方法を図５に示
したフローチャートを参照して説明する。The calibration method according to this embodiment will be described below with reference to the flow chart shown in FIG.
【００２０】ステップＳ１：まず、較正用装置１０に備
えられた較正用コイル１２（薄膜コイル１２x ，１
２y ，１２z ）のコイル中心座標（ｘj ，ｙj ，ｚj ）
および方向（コイル面の法線方向）（θj ，ψj ）を、
例えば基台１１の角部ＣＲの位置および方向を基準とし
て、スタイラスペンなどの３次元位置測定装置で測定す
る。なお、薄膜コイル１２x ，１２y ，１２z の形状
は、設計値あるいは実測値から知ることができ、何れに
しても既知である。Step S1: First, the calibration coil 12 (thin film coil 12 x , 1
2 y , 12 z ) coil center coordinates (x j , y j , z j )
And direction (normal direction of the coil surface) (θ j , ψ j )
For example, the position and direction of the corner portion CR of the base 11 is used as a reference, and measurement is performed with a three-dimensional position measuring device such as a stylus pen. The shapes of the thin film coils 12 x , 12 y , and 12 z can be known from design values or actual measurement values, and are known in any case.
【００２１】ステップＳ２：相対位置および方向が既知
となった較正用コイル１２群を、マルチチャンネルＳＱ
ＵＩＤセンサ１のデュワー２の下方の任意の位置にセッ
トする。Step S2: The calibration coil 12 group whose relative position and direction are known is set to the multi-channel SQ.
The UID sensor 1 is set at an arbitrary position below the dewar 2.
【００２２】ステップＳ３：選択駆動部１３によって、
各較正用コイル１２の薄膜コイル１２x ，１２y ，１２
z に順に既知の電流を流して磁場を発生させ、各々の磁
場発生状態の下で各ＳＱＵＩＤセンサ３の出力電圧（測
定電圧値）Ｖexp を測定する。Step S3: By the selection drive unit 13,
Thin film coils 12 x , 12 y , 12 of each calibration coil 12
A known current is sequentially applied to z to generate a magnetic field, and the output voltage (measured voltage value) V exp of each SQUID sensor 3 is measured under each magnetic field generation state.
【００２３】ステップＳ４：各測定電圧値Ｖexp と、同
じ磁場状態下で計算によって求められた各ＳＱＵＩＤセ
ンサ３の出力電圧値（仮定電圧値）Ｖthとの２乗誤差が
最小となるような検出／補償コイル４，５の位置，方向
および磁束／電圧変換係数を求める。以下、このステッ
プＳ４の詳細について説明する。Step S4: The square error between each measured voltage value V exp and the output voltage value (assumed voltage value) V th of each SQUID sensor 3 calculated under the same magnetic field condition is minimized. The positions and directions of the detection / compensation coils 4 and 5 and the magnetic flux / voltage conversion coefficient are obtained. The details of step S4 will be described below.
【００２４】いま、ｊ番目の較正用コイル１２（具体的
には較正用コイル１２内の一つの薄膜コイル）に既知の
電流を流したときに、ｉ番目のＳＱＵＩＤセンサ３の出
力電圧（仮定電圧値）は、次式（１）で表すことができ
る。 Ｖth＝ｋ（VBd ・Vnd −VBc ・Vnc ） ……（１）Now, when a known current is applied to the j-th calibration coil 12 (specifically, one thin-film coil in the calibration coil 12), the output voltage of the i-th SQUID sensor 3 (the assumed voltage The value) can be expressed by the following equation (1). V th = k (VB d · Vn d −VB c · Vn c ) ... (1)
【００２５】上式（１）において、ｋは、磁束／電圧変
換係数である。VBd は、検出コイル４のコイル中心での
磁場ベトクルであって、検出コイル４の中心位置
（ｘdi，ｙdi，ｚdi）および較正用コイル１２（具体的
には薄膜コイル）の位置および方向により決まる。VBc
は、補償コイル５のコイル中心での磁場ベトクルであっ
て、補償コイル５の中心位置（ｘci，ｙci，ｚci）およ
び較正用コイル１２（具体的には薄膜コイル）の位置お
よび方向により決まる。Vnd は、検出コイル４の法線ベ
クトル、つまり方向（θdi，ψdi）である。Vnc は、補
償コイル５の法線ベクトル、つまり方向（θci，ψci）
である。In the above equation (1), k is a magnetic flux / voltage conversion coefficient. VB d is a magnetic field vector at the coil center of the detection coil 4, and includes the center position (x di , y di , z di ) of the detection coil 4 and the position of the calibration coil 12 (specifically, a thin film coil). It depends on the direction. VB c
Is a magnetic field vector at the coil center of the compensation coil 5, depending on the center position (x ci , y ci , z ci ) of the compensation coil 5 and the position and direction of the calibration coil 12 (specifically, thin film coil). Decided. Vn d is the normal vector of the detection coil 4 is i.e. the direction (θ di, ψ di). Vn c is the normal vector of the compensation coil 5, that is, the direction (θ ci , ψ ci ).
Is.
【００２６】ここで、磁束／電圧変換係数ｋ、検出コイ
ル４の中心位置（ｘdi，ｙdi，ｚdi）と方向（θdi，ψ
di）、および補償コイル５の中心位置（ｘci，ｙci，ｚ
ci）と方向（θci，ψci）は未知であり、較正用コイル
１２の位置および方向はステップＳ１の測定により既知
である。したがって、上式で表される各ＳＱＵＩＤセン
サの仮定電圧値Ｖthは、１１個の未知のパラメータ群
（ｋ，ｘdi，ｙdi，ｚdi，θdi，ψdi，ｘci，ｙci，ｚ
ci，θci，ψci）によって決定される値である。Here, the magnetic flux / voltage conversion coefficient k, the center position (x di , y di , z di ) and direction (θ di , ψ) of the detection coil 4 are used.
di ) and the center position (x ci , y ci , z of the compensation coil 5
ci ) and the direction (θ ci , ψ ci ) are unknown, and the position and direction of the calibration coil 12 are known by the measurement in step S1. Therefore, the assumed voltage value V th of each SQUID sensor expressed by the above equation is 11 unknown parameter groups (k, x di , y di , z di , θ di , ψ di , x ci , y ci , z
ci , θ ci , ψ ci ).
【００２７】そこで、各ＳＱＵＩＤセンサ３ごとに得ら
れる複数の測定電圧値Ｖexp （本実施例では、一つのＳ
ＱＵＩＤセンサ３について、それぞれ３個の薄膜コイル
で構成される２５個の較正用コイル１２によって順に発
生させた磁場を測定しているので、７５個の測定電圧値
が得られる）と、各々の測定電圧値Ｖexp が得られたと
同じ磁場状態、即ち、較正用コイル１２の位置および方
向と、これに流す電流を同一にしたと仮定した場合に算
出される各ＳＱＵＩＤセンサの複数の仮定電圧値Ｖthと
の２乗誤差（次式（２）で表されるΔ）を最小とするよ
うに、上記１１個のパラメータ群を最適化して、デュワ
ー２内に収納された検出／補償コイル４，５の位置，方
向および磁束／電圧変換係数の各値を求める。 Δ＝Σ（Ｖth−Ｖexp ）2 ／ΣＶexp 2 ……（２） Therefore, a plurality of measured voltage values V exp obtained for each SQUID sensor 3 (in this embodiment, one S
For the QUID sensor 3, since the magnetic fields generated in order by the 25 calibration coils 12 each composed of 3 thin film coils are measured, 75 measurement voltage values can be obtained) and each measurement. A plurality of hypothetical voltage values V of each SQUID sensor calculated under the same magnetic field condition in which the voltage value V exp is obtained, that is, assuming that the position and direction of the calibration coil 12 and the current flowing through the same are assumed to be the same. The eleven parameter groups are optimized so as to minimize the squared error with th (Δ represented by the following equation (2)), and the detection / compensation coils 4, 5 housed in the dewar 2 are optimized. Calculate the position, direction, and magnetic flux / voltage conversion coefficient. Δ = Σ (V th −V exp ) 2 / ΣV exp 2 (2)
【００２８】以上のようにして求められた検出／補償コ
イル４，５の位置，方向は、デュワー２の下方にセット
された較正用コイル１２群の座標系ｘ−ｙ−ｚにおける
値である。これらの値から、例えば中央に配置された検
出／補償コイル４，５を基準とした各検出／補償コイル
４，５の相対的な位置関係および方向が求められる。こ
のようにして各検出／補償コイル４，５の相対的な位置
関係および方向を知れることができれば、デュワー２に
対する各検出／補償コイル４，５の位置関係を必ずしも
把握する必要はない。生体磁気計測時に被検体上の既知
の位置および方向に複数の小コイルを取り付け、これら
の小コイルに既知電流を順に流したときに発生する磁場
を、相対的な位置関係が判っている各ＳＱＵＩＤセンサ
で測定すれば、被検体と各ＳＱＵＩＤセンサの位置関係
を容易に把握することができるからである。The positions and directions of the detection / compensation coils 4 and 5 thus obtained are values in the coordinate system xyz of the group of calibration coils 12 set below the dewar 2. From these values, for example, the relative positional relationship and direction of the detection / compensation coils 4 and 5 with reference to the detection / compensation coils 4 and 5 arranged in the center are obtained. If the relative positional relationship and direction of the detection / compensation coils 4 and 5 can be known in this way, it is not necessary to grasp the positional relationship of the detection / compensation coils 4 and 5 with respect to the dewar 2. Each SQUID whose relative positional relationship is known for the magnetic field generated when a plurality of small coils are attached at known positions and directions on the subject during biomagnetism measurement, and known currents are sequentially applied to these small coils. This is because the positional relationship between the subject and each SQUID sensor can be easily grasped by measuring with the sensor.
【００２９】なお、上記実施例ではマルチチャンネルＳ
ＱＵＩＤセンサのデュワーの下方に複数個の較正用コイ
ルを配置して各ＳＱＵＩＤセンサの位置，方向および磁
束／電圧変換係数を測定したが、この発明はこれに限ら
ず、例えば一個の較正用コイルを複数箇所の予め知られ
た位置および方向に順に移動させ、各箇所でその較正用
コイルに既知電流を流して磁場を発生させることによ
り、各ＳＱＵＩＤセンサの位置，方向および磁束／電圧
変換係数を測定するように構成してもよい。In the above embodiment, the multi-channel S
The position, direction and magnetic flux / voltage conversion coefficient of each SQUID sensor were measured by arranging a plurality of calibration coils below the dewar of the QUID sensor, but the present invention is not limited to this. Measure the position, direction and magnetic flux / voltage conversion coefficient of each SQUID sensor by moving to multiple known positions and directions in sequence and flowing a known current to the calibration coil at each position to generate a magnetic field. It may be configured to do so.
【００３０】[0030]
【発明の効果】以上の説明から明らかなように、この発
明によれば、予め知られた複数箇所の位置に予め知られ
た方向に較正用コイルを配置し、各箇所で前記較正用コ
イルに既知電流を順に流して磁場を生成し、そのときの
各ＳＱＵＩＤセンサの出力電圧を測定し、その測定電圧
値と、同様の条件で磁場を検出したと仮定したときに各
ＳＱＵＩＤセンサで検出されるべき出力電圧（仮定電圧
値）とを比較し、前記仮定電圧値が前記測定値に最も近
い値になるように、前記仮定電圧値に含まれる未知のパ
ラメータ群（すなわち、各ＳＱＵＩＤセンサの位置，方
向および磁束／電圧変換係数）を最適化することによ
り、各ＳＱＵＩＤセンサの位置，方向および磁束／電圧
変換係数を求めているので、冷媒容器内に収納された状
態で各ＳＱＵＩＤセンサの位置，方向および磁束／電圧
変換係数を正確に求めることができる。また、冷媒容器
内に各ＳＱＵＩＤセンサを組み込む前に、各ＳＱＵＩＤ
センサごとに磁束／電圧変換係数を測定する必要もない
ので、生体磁気計測装置の較正を短時間で行なうことが
できる。As is apparent from the above description, according to the present invention, the calibration coils are arranged in a known direction at a plurality of known positions, and the calibration coils are provided at the respective positions. A known current is sequentially passed to generate a magnetic field, the output voltage of each SQUID sensor at that time is measured, and it is detected by each SQUID sensor when the measured voltage value and the magnetic field are detected under the same conditions. Power voltage (assumed voltage value), and an unknown parameter group included in the assumed voltage value (that is, the position of each SQUID sensor, so that the assumed voltage value is closest to the measured value). Since the position, direction and magnetic flux / voltage conversion coefficient of each SQUID sensor are obtained by optimizing the direction and magnetic flux / voltage conversion coefficient), each SQUID sensor is stored in the refrigerant container. Position Sa can be determined accurately the direction and flux / voltage conversion factor. Also, before installing each SQUID sensor in the refrigerant container,
Since it is not necessary to measure the magnetic flux / voltage conversion coefficient for each sensor, the biomagnetism measuring device can be calibrated in a short time.
【図１】この発明に係る生体磁気計測装置の較正方法の
一実施例の説明図である。FIG. 1 is an explanatory diagram of an embodiment of a calibration method for a biomagnetism measuring device according to the present invention.
【図２】検出／補償コイルの一例を示す斜視図である。FIG. 2 is a perspective view showing an example of a detection / compensation coil.
【図３】検出／補償コイルの位置および方向の説明図で
ある。FIG. 3 is an explanatory diagram of positions and directions of detection / compensation coils.
【図４】較正用コイルの一例を示す斜視図である。FIG. 4 is a perspective view showing an example of a calibration coil.
【図５】実施例方法のフローチャートである。FIG. 5 is a flow chart of an example method.
１…マルチチャンネルＳＱＵＩＤセンサ ２…デュワー（冷媒容器） ３…ＳＱＵＩＤセンサ ４…検出コイル ５…補償コイル １０…較正用装置 １２…較正用コイル １３…選択駆動部 1 ... Multi-channel SQUID sensor 2 ... Dewar (refrigerant container) 3 ... SQUID sensor 4 ... Detection coil 5 ... Compensation coil 10 ... Calibration device 12 ... Calibration coil 13 ... Selection drive unit
Claims (1)
コイルに接続されたＳＱＵＩＤ素子で構成されたＳＱＵ
ＩＤセンサを３次元配置して冷媒容器内に収納したマル
チチャンネルＳＱＵＩＤセンサの各ＳＱＵＩＤセンサの
検出／補償コイルの位置，方向および磁束／電圧変換係
数を測定する、生体磁気計測装置の較正方法であって、
（ａ）予め知られた複数箇所の位置に予め知られた方向
に較正用コイルを配置し、各箇所で較正用コイルに既知
電流を順に流して磁場を生成する過程と、（ｂ）前記各
箇所で較正用コイルによって生成された磁場を任意の位
置にセットされた各ＳＱＵＩＤセンサで検出して、それ
ぞれの測定電圧値を得る過程と、（ｃ）前記較正用コイ
ルを前記各箇所に同様に配置して同じ既知電流を流した
と仮定した場合に、前記各ＳＱＵＩＤセンサで検出され
るべき各出力電圧（仮定電圧値）を、前記各ＳＱＵＩＤ
センサの検出／補償コイルの位置，方向および磁束／電
圧変換係数からなる未知のパラメータ群を使って表し、
前記仮定電圧値が前記測定電圧値に最も近い値になるよ
うに、前記未知のパラメータ群を最適化することによ
り、各ＳＱＵＩＤセンサの検出／補償コイルの位置，方
向および磁束／電圧変換係数を求める過程と、を備えた
ことを特徴とする生体磁気計測装置の較正方法。1. A SQUI comprising a detection coil, a compensation coil, and an SQUID element connected to these coils.
A method for calibrating a biomagnetism measuring device, which measures the position, direction, and magnetic flux / voltage conversion coefficient of the detection / compensation coil of each SQUID sensor of a multi-channel SQUID sensor in which ID sensors are three-dimensionally arranged and stored in a refrigerant container. hand,
(A) a step of arranging a calibration coil in a known direction at a plurality of known positions, and sequentially supplying a known current to the calibration coil at each position to generate a magnetic field; The magnetic field generated by the calibration coil at each location is detected by each SQUID sensor set at an arbitrary position to obtain each measured voltage value, and (c) the calibration coil is similarly provided at each location. Assuming that the SQUIDs are arranged and the same known current flows, the output voltages (hypothesized voltage values) to be detected by the SQUID sensors are set to the SQUIDs.
It is expressed using an unknown parameter group consisting of the position / direction of the sensor detection / compensation coil and the magnetic flux / voltage conversion coefficient,
By optimizing the unknown parameter group so that the assumed voltage value becomes the closest value to the measured voltage value, the position / direction and the magnetic flux / voltage conversion coefficient of the detection / compensation coil of each SQUID sensor are obtained. A method for calibrating a biomagnetism measuring device, comprising:
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|---|---|---|---|
| JP7074415A JP2795212B2 (en) | 1995-03-06 | 1995-03-06 | Calibration method for biomagnetic measurement device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7074415A JP2795212B2 (en) | 1995-03-06 | 1995-03-06 | Calibration method for biomagnetic measurement device |
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| Publication Number | Publication Date |
|---|---|
| JPH08238225A true JPH08238225A (en) | 1996-09-17 |
| JP2795212B2 JP2795212B2 (en) | 1998-09-10 |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20010069719A (en) * | 2000-12-18 | 2001-07-25 | 김상범 | Analyzing Method of Measured Value for Physical Energy |
| KR20010069718A (en) * | 2000-12-18 | 2001-07-25 | 김상범 | Analyzing Method of Measured Value for Physical Energy |
| US6522908B1 (en) * | 1999-10-06 | 2003-02-18 | Hitachi, Ltd. | Biomagnetic field measuring apparatus |
| KR100409039B1 (en) * | 2000-06-23 | 2003-12-11 | (주)밸런스텍 | A method for an analysis of physical energy flow |
| CN104698416A (en) * | 2013-12-05 | 2015-06-10 | 中国科学院上海微***与信息技术研究所 | Calibration circuit structure and calibration method thereof |
| CN108024755A (en) * | 2015-09-10 | 2018-05-11 | 株式会社理光 | magnetic measuring device |
-
1995
- 1995-03-06 JP JP7074415A patent/JP2795212B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6522908B1 (en) * | 1999-10-06 | 2003-02-18 | Hitachi, Ltd. | Biomagnetic field measuring apparatus |
| KR100409039B1 (en) * | 2000-06-23 | 2003-12-11 | (주)밸런스텍 | A method for an analysis of physical energy flow |
| KR20010069719A (en) * | 2000-12-18 | 2001-07-25 | 김상범 | Analyzing Method of Measured Value for Physical Energy |
| KR20010069718A (en) * | 2000-12-18 | 2001-07-25 | 김상범 | Analyzing Method of Measured Value for Physical Energy |
| CN104698416A (en) * | 2013-12-05 | 2015-06-10 | 中国科学院上海微***与信息技术研究所 | Calibration circuit structure and calibration method thereof |
| CN104698416B (en) * | 2013-12-05 | 2017-10-27 | 中国科学院上海微***与信息技术研究所 | Calibration Circuit structure and the method demarcated using the structure |
| CN108024755A (en) * | 2015-09-10 | 2018-05-11 | 株式会社理光 | magnetic measuring device |
| CN108024755B (en) * | 2015-09-10 | 2021-07-30 | 株式会社理光 | Magnetic measuring device |
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| JP2795212B2 (en) | 1998-09-10 |
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