JP4136089B2 - Ultrasonic diagnostic equipment - Google Patents

Description

（作用）
次に、このように構成された本実施の形態の作用について説明する。
【００４３】
体腔内に超音波内視鏡１０１の挿入部１０２を挿入し、超音波画像処理装置１１３により超音波内視鏡１０１の先端に設けられた超音波振動１０子５及びフレキシブルシャフト１０６を駆動しラジアルスキャンすると共に超音波内視鏡１０１の挿入部１０２を挿抜しリニアスキャンすることでスパイラルスキャンにより３次元超音波画像を形成する。
【００４４】
このとき、電流発生器１１６より超音波内視鏡１０１の磁気ソース１０８に電流を供給し磁気ソース１０８により磁場を発生させる。そして、この磁場を所定の位置に配置されている磁気センサ１１５により磁場の強度を検出し、位置検出装置１１７において検出した磁場の強度から、磁気ソース１０８及び磁気センサ１１５の各コイルが軸ずれすることなく正確に直交しているものとして、理論的な位置データｒ（ｘ、ｙ、ｚ）を算出し補正装置１１９にこの位置データｒ（ｘ、ｙ、ｚ）を出力する。
【００４５】
補正装置１１９では、ＲＯＭ１１８に格納されているテーブル形式の補正データ（表１参照）を読み込み、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）が、テーブル形式の補正データ中のどの位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）に最も近いか判断し、最も近い位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）に対応する座標データＲ_i（Ｘ_i、Ｙ_i、Ｚ_i）を、順次出力される位置データｒ（ｘ、ｙ、ｚ）を補正した位置データｒ’（ｒ’＝Ｒ_i）として超音波画像処理装置１１３に出力し、超音波画像形成装置１１３は、正確な３次元超音波画像をモニタ１１２に表示する。
【００４６】
このとき、位置データｒ（ｘ、ｙ、ｚ）がテーブル形式の補正データ中のどの位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）に最も近いかの判断は、以下の式（１）により行う。
【００４７】
【数１】

（効果）
このように本実施の形態では、磁気ソース１０８から発せられた磁場を磁気センサ１１５で検出し、位置検出装置１１７が算出した位置データｒ（ｘ、ｙ、ｚ）を補正装置１１９で補正データにより座標データＲ_i（Ｘ_i、Ｙ_i、Ｚ_i）に変換して、補正した正確な位置データｒ’（ｒ’＝Ｒ_i）として超音波画像処理装置１１３に出力するので、たとえ磁気ソース１０８あるいは磁気センサ１１５の各コイルが軸ずれしていても、正確な正確な位置データｒ’（ｒ’＝Ｒ_i）が超音波画像処理装置１１３に出力されるので、正確な３次元超音波画像をモニタ１１２に表示することができる。
【００４８】
なお、上記実施の形態では超音波内視鏡１０１の先端に磁場を発生する磁気ソースを設け、それを磁気センサで検出するとしたが、超音波内視鏡１０１の先端に磁気センサを設け、外部から磁場を発生させる場合においても本実施の形態が適用できることはいうまでもない。
【００４９】
図１０及び図１１は各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第２の実施の形態に係わり、図１０は補正装置における線形内挿による推定式を説明する第１の説明図、図１１は図１０により説明した推定式の第２の説明図である。
【００５０】
（構成）
本実施の形態は、図６ないし図９で説明した各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第１の実施の形態の構成と同じであり、補正装置１１９における補正動作が異なるのみであるので、異なる点のみ説明する。
【００５１】
（作用）
図６ないし図９で説明した実施の形態では、位置検出装置１１７が算出した位置データｒ（ｘ、ｙ、ｚ）を補正装置１１９で補正データにより座標データＲ_i（Ｘ_i、Ｙ_i、Ｚ_i）に変換して、補正した正確な位置データｒ’（ｒ’＝Ｒｉ）としていたが、本実施の形態では、複数の格子点での位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）を基に、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）の正確な座標データＲ’（Ｘ’、Ｙ’、Ｚ’）を推定し、この座標データＲ’（Ｘ’、Ｙ’、Ｚ’）を超音波画像処理装置１１３に出力するものである。
【００５２】
詳細には、まず、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）に対して、ＲＯＭ１１８に格納されているテーブル形式の補正データ（表１参照）の中の位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）のうち最も近い順から４つの格子点の位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）を抽出する。なお、近いか否かの判断は、式（１）により行う。
【００５３】
次に、抽出した４つの格子点の番号を位置データｒ（ｘ、ｙ、ｚ）に近い順から、ｉ＝０、１、２、３と付け直す。
【００５４】
そして、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）と、抽出された４つの格子点の位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）（ｉ＝０、１、２、３）及びこの４つの正確な座標データ座標データｒ_i（ｘ_i、ｙ_i、ｚ_i）（ｉ＝０、１、２、３）とから、位置データｒ（ｘ、ｙ、ｚ）の正確な座標データＲ’（Ｘ’、Ｙ’、Ｚ’）を推定する。
【００５５】
具体的には、この座標データＲ’（Ｘ’、Ｙ’、Ｚ’）を以下の式（２）ないし式（５）による線形内挿により推定する。
【００５６】
【数２】

【数３】

【数４】

【数５】

なお、式（５）でのベクトルｒ、ｒ₀、ｒ₁、ｒ₂、ｒ₃は、３行１列の列ベクトルとして扱う。従って、［ｒ₁−ｒ₀ ｒ₂−ｒ₀ ｒ₃−ｒ₀］は３行３列の行列である。
【００５７】
そして、得られた座標データＲ’（Ｘ’、Ｙ’、Ｚ’）を、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）に対応する補正された正確な位置データとして超音波画像処理装置１１３に出力する。
【００５８】
一般に、ｎ次元空間Ｖで定義された連続関数ｆ上の値ｆ（ｒ）を、ｆ上の複数の既知データｆ（ｒ₀）、ｆ（ｒ₁）、ｆ（ｒ₂）、ｆ（ｒ₃）、……から線形内挿して推定する際には、ｎ＋１個のデータｆ（ｒ_i）（ｉ＝０〜ｎ）があれば推定することができる。このとき、推定値をｆ’（ｒ）として、以下の式（６）及び式（７）のように書くことができ、本実施の形態での式（２）ないし（５）はこの式（６）及び式（７）を応用したものである。
【００５９】
【数６】

【数７】

式（６）及び式（７）の導出方法の詳細は省略するが、概略は以下の通りである。簡単のためｎ＝２の場合で説明する。
【００６０】
図１０に２次元空間（従って平面）Ｖ上で定義された連続関数ｆを示す。これは式（６）でのｎ＝２の場合に相当する。ここで、ｆを示す軸を含めた３（ｎ＋１）次元空間を考える。Ｖ上の３点ｒ₀、ｒ₁、ｒ₂は、対応する関数値ｆ（ｒ₀）、ｆ（ｒ₁）、ｆ（ｒ₂）を含め、この３次元空間上では図９に示す点Ｐ₀、Ｐ₁、Ｐ₂と表現することができる。ここで、ｆ（ｒ）を線形内挿により推定するということは、Ｖ上の点ｒに対応する点Ｐが平面Ｐ₀Ｐ₁Ｐ₂上に存在すると仮定して、その推定値ｆ’（ｒ）を求めることである。これを定式化すると、以下の式（８）及び式（９）のようになる。
【００６１】
ｒが平面Ｖ上に存在する：
【数８】

Ｐが平面Ｐ₀Ｐ₁Ｐ₂上に存在する：
【数９】

ｒ₁−ｒ₀、ｒ₂−ｒ₀が１次独立（ｎ＝２の場合、ｒ₀、ｒ₁、ｒ₂が１直線上に存在しない）であるようなデータであることを仮定すると、Ｃ_i＝Ｃ_i’が導かれる。結局、式（８）、式（９）を解いて成分の１つであるｆ’（ｒ）を求めることで、式（６）、式（７）が導かれ、ｆ（ｒ）の推定が可能となる。
【００６２】
次に、式（６）、式（７）を確かめるため、図１１に示すような連続関数が１次元空間（ｘ軸上）で定義されているような場合を考える。ｎ＝１とおけばよいわけであるから、この場合は、以下のように書くことができる。
【００６３】
【数１０】
ｆ’（ｘ）＝ｆ（ｘ₀）＋Ｃ（ｆ（ｘ₁）−ｆ（ｘ₀）） …（１０）
そして、ｎ＝１のときの式（７）を式（１０）に代入してＣを消去すると、
【数１１】

となり、これは一般の連続関数の線形内挿の式となる。
【００６４】
（効果）
このように本実施の形態では、図６ないし図９で説明した各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第１の実施の形態では、格子間隔以下の刻みの補正された位置データを得ることはできなかったが、線形内挿して座標データを推定するようにしたので、格子間隔以下の細かいデータを取得することができる。
【００６５】
また、格子間隔以下の細かいデータを取得することができるため、格子間隔を広げ格子点を少なくすることで、工場出荷時の補正データ作成のための工数を削減できる。あるいは格子全体を大きくし、補正が可能な領域を広げることも容易である。
【００６６】
図１２は各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第３の実施の形態に係る補正装置における格子点抽出方法を説明する説明図である。
【００６７】
（構成）
本実施の形態は、図６ないし図９で説明した各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第１の実施の形態の構成と同じであり、ＲＯＭ１１８に格納されているテーブル形式の補正データと補正装置１１９における補正動作が異なるのみであるので、異なる点のみ説明する。
【００６８】
（作用）
各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第１及び第２の実施の形態では、正確な座標データＲ_i（Ｘ_i、Ｙ_i、Ｚ_i）を一定の刻みにした表１に示したテーブル形式の補正データをＲＯＭ１１８に格納したが、本実施の形態では、この補正データを、さらに位置検出装置１１７が算出した位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）を一定の刻みとした表２に示されるテーブル形式の第２の補正データを作成し、この第２の補正データをＲＯＭ１１８に格納する。この第２の補正データは、一定の刻みをもった位置データｒ_i（ｘ_i、ｙ_i、ｚ_i）に対する正確な座標データＲ_i（Ｘ_i、Ｙ_i、Ｚ_i）を、各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第２の実施の形態で説明した方法で推定して得ることができる。この演算、作業は工場出荷時等に行う。
【００６９】
【表２】

このようにすることで、図１２に示すように、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）を囲むような位置データを持つ位置データｒ（ｘ、ｙ、ｚ）近傍の８個の格子点（位置データｒ_i（ｘ_i、ｙ_i、ｚ_i））を、位置データｒ（ｘ、ｙ、ｚ）の値から瞬時に抽出することができる。このため、上記第２の実施に形態における位置データｒ（ｘ、ｙ、ｚ）に最も近い順から４点を抽出する動作は、結局この８点から抽出すればよく、動作を簡略化することができる。その他の作用は上記第２の実施に形態と同じである。
【００７０】
（効果）
このように本実施の形態では、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）を囲むような位置データを持つ位置データｒ（ｘ、ｙ、ｚ）近傍の８個の格子点（位置データｒ_i（ｘ_i、ｙ_i、ｚ_i））を、位置データｒ（ｘ、ｙ、ｚ）の値から瞬時に抽出することができるので、全ての格子点について位置データ間の距離｜ｒ−ｒ_i｜を計算することなく、簡単に位置データｒ（ｘ、ｙ、ｚ）に最も近い順から４点を抽出することができる。このため、位置検出装置１１７から順次出力される位置データｒ（ｘ、ｙ、ｚ）に対応した正確な座標データＲを推定する演算速度を飛躍的に向上させることができる。
【００７１】
［付記２］
（付記項２−１） 磁場を発生する送信コイルと、前記送信コイルが発生する磁場を検出する受信コイルとを具備し、前記送信コイル及び前記受信コイルのうちいずれか一方が超音波内視鏡の先端に配置され、前記受信コイルが検出した検出信号により前記超音波内視鏡の先端の位置を算出する位置算出手段を備え、前記送信コイルもしくは前記受信コイルのうち少なくとも一方が軸が直交する複数のコイルからなるコイル群である超音波診断装置において、
前記コイル群の軸ずれに起因する位置ずれを補正する補正手段を備えた
ことを特徴とする超音波診断装置。
【００７２】
（付記項２−２） 前記位置ずれを補正する補正データを記録した記録手段を備え、
前記補正手段は、前記補正データに基づいて前記位置ずれを補正する
ことを特徴とする付記項２−１に記載の超音波診断装置。
【００７３】
（付記項２−３） 前記補正データが、前記位置算出手段が算出した位置データと、前記位置データとは別に測定された実測値との対応を示すデータである
ことを特徴とする付記項２−２に記載の超音波診断装置。
【００７４】
（付記項２−４） 前記補正手段は、前記位置算出手段が算出した位置データを線形内挿して得られた値を用いて補正する
ことを特徴とする付記項２−２または２−３に記載の超音波診断装置。
【００７５】
【発明の効果】
以上説明したように本発明の超音波診断装置によれば補正手段が超音波内視鏡を構成する金属部品によって生じる磁場に歪みによる受信コイルの検出信号の変化を補正するので、超音波内視鏡を構成する金属部品による磁界の歪みの影響を排除し、超音波内視鏡の先端の正確な位置及び配向の算出ができるという効果がある。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る超音波内視鏡の先端の構成を示す断面図
【図２】図１の超音波内視鏡を備えた超音波診断装置の構成を示す構成図
【図３】図２の位置検出装置の構成を示す構成図
【図４】図３の補正回路に予め記憶されている重み付け係数を説明する第１の説明図
【図５】図３の補正回路に予め記憶されている重み付け係数を説明する第２の説明図
【図６】各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第１の実施の形態に係る超音波内視鏡の先端の構成を示す断面図
【図７】図６の超音波内視鏡を備えた超音波診断装置の構成を示す構成図
【図８】図７の磁気センサの構成を示す構成図
【図９】図７のＲＯＭの格納されている補正データを説明する説明図
【図１０】各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第２の実施の形態に係る補正装置における線形内挿による推定式を説明する第１の説明図
【図１１】図１０により説明した推定式の第２の説明図
【図１２】各コイルに軸ずれがあっても正確に超音波内視鏡の先端の位置を算出することのできる第３の実施の形態に係る補正装置における格子点抽出方法を説明する説明図
【符号の説明】
１…超音波内視鏡
２…挿入部
３…硬性部
４…シース
５…超音波振動子
６…フレキシブルシャフト
７…超音波伝達媒体
８…磁気ソース
１１…超音波診断装置
１２…モニタ
１３…超音波画像形成装置
１６…磁気センサ
１９…位置検出装置
２０…パソコン
２１…補正回路
２２…位置算出回路
２３…電流発生器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus characterized by a processing portion of magnetic field detection data for detecting a tip position of an ultrasonic endoscope.
[0002]
[Prior art]
In recent years, an ultrasonic endoscope having an ultrasonic transducer is inserted into a body cavity, ultrasonic waves are transmitted and received from the ultrasonic transducer, and a diagnosis is performed by drawing the state of the body from the echo signal. An ultrasonic diagnostic imaging apparatus is generally used.
[0003]
An ultrasonic endoscope in such an ultrasonic diagnostic imaging apparatus is usually configured such that an ultrasonic transducer is provided at the tip of a flexible shaft and the outer periphery thereof is covered with a cylindrical sheath.
[0004]
Then, by rotating the ultrasonic transducer through the flexible shaft, the radial scan type device that radiates ultrasonic waves in the radial direction, or moving the flexible shaft and ultrasonic transducer in the insertion axis direction With a linear scan method that irradiates ultrasonic waves in a direction orthogonal to the axial direction of the flexible shaft, a spiral scan method (three-dimensional method) that combines the above-mentioned radial scan method and linear scan method Various things have been proposed.
[0005]
The spiral scan method is such that linear scanning is performed simultaneously with radial scanning, so that a plurality of continuous ultrasonic tomographic images can be obtained. Then, some processing is performed on the echo data (image data) obtained thereby to obtain three-dimensional image data.
[0006]
This type of ultrasonic diagnostic imaging device normally captures the echo data of the test site as a series of two-dimensional ultrasound tomographic images, and constructs a 3D image of the test site from the acquired echo data. And display it.
[0007]
However, in the ultrasonic diagnostic imaging apparatus that constructs a three-dimensional image, in general, linear scanning is performed by inserting and removing an ultrasonic endoscope by an operator's hand, so that the position of the tip portion in linear scanning is inaccurate. In addition, since the direction of the radial scan is not known in a curved body cavity, there is a problem that an accurate three-dimensional image cannot be constructed.
[0008]
Therefore, for example, in Japanese Patent Application Laid-Open No. 6-261900, a magnetic source including a coil is provided at the tip, a magnetic field from the magnetic source is detected by a magnetic sensor provided outside, and an ultrasonic transducer for linear scanning is used. There has been proposed an ultrasonic diagnostic imaging apparatus capable of constructing an accurate three-dimensional image by calculating an axial position and a scan plane orientation in a radial scan.
[0009]
[Problems to be solved by the invention]
However, in JP-A-6-261900, a magnetic source is provided at the distal end of the insertion portion. Generally, a rigid portion made of a metal member is provided at the distal end of the insertion portion, and the rigid portion made of this metal member. If a magnetic source is provided in the vicinity, there is a problem that a magnetic field generated from the magnetic source is distorted due to the influence of a hard part made of a metal member, and an accurate position and orientation cannot be calculated.
[0010]
The present invention has been made in view of the above circumstances, eliminates the influence of magnetic field distortion caused by metal parts constituting the ultrasonic endoscope, and calculates the exact position and orientation of the tip of the ultrasonic endoscope. An object of the present invention is to provide an ultrasonic diagnostic apparatus.
[0011]
  An ultrasonic diagnostic apparatus according to the present invention includes a transmission coil that generates a magnetic field and a reception coil that detects a magnetic field generated by the transmission coil, and any one of the transmission coil and the reception coil is within an ultrasonic wave. In an ultrasonic diagnostic apparatus comprising a position information calculation unit that is disposed at a distal end of an endoscope and calculates position information of the distal end of the ultrasonic endoscope based on a detection signal detected by the receiving coil.
  Detection correction information generating means for generating detection signal correction information based on a detection signal detected by the receiving coil when the tip of the ultrasonic endoscope is disposed at a predetermined position of a virtual point in space;
Detection signal correction means for correcting the detection signal output from the receiving coil using the detection signal correction information;
  It is configured with.
[0012]
In the ultrasonic diagnostic apparatus of the present invention, the correction means corrects the change in the detection signal of the reception coil due to distortion in the magnetic field generated by the metal parts constituting the ultrasonic endoscope, thereby enabling the ultrasonic endoscope to The influence of the distortion of the magnetic field due to the metal parts to be configured is eliminated, and the accurate position and orientation of the tip of the ultrasonic endoscope can be calculated.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
1 to 5 relate to an embodiment of the present invention, FIG. 1 is a cross-sectional view showing the configuration of the tip of an ultrasonic endoscope, and FIG. 2 is an ultrasonic diagnosis provided with the ultrasonic endoscope of FIG. 3 is a block diagram showing the configuration of the apparatus, FIG. 3 is a block diagram showing the configuration of the position detection apparatus of FIG. 2, and FIG. 4 is a first explanatory diagram explaining weighting coefficients stored in advance in the correction circuit of FIG. 5 is a second explanatory diagram for explaining the weighting coefficient stored in advance in the correction circuit of FIG.
[0015]
(Constitution)
As shown in FIG. 1, the ultrasonic endoscope 1 has a hard rigid portion 3 made of a metal member at the distal end of the insertion portion 2, and a sheath integrally connected to the distal end of the rigid portion 3. 4 is provided. In this sheath 4, an ultrasonic transducer 5 is rotatably connected to a flexible shaft 6 that passes through the insertion portion 2 and the rigid portion 3, and an ultrasonic transmission medium 7 is placed inside the sheath 4. Is filled. Further, the hard part 3 has a built-in magnetic source 8 that generates a magnetic field in two orthogonal directions, for example.
[0016]
As shown in FIG. 2, the ultrasonic diagnostic apparatus 11 according to the present embodiment drives the ultrasonic endoscope 1, the ultrasonic transducer 5 and the flexible shaft 6 of the ultrasonic endoscope 1, and performs super An ultrasonic image forming apparatus 13 that forms a three-dimensional ultrasonic image by echo data from the ultrasonic transducer 5 and displays the three-dimensional ultrasonic image on the monitor 12, and the insertion portion 2 of the ultrasonic endoscope 1 are provided in the body cavity. A magnetic sensor 16 comprising a plurality of, for example, 16 coils for detecting the magnetic field generated by the magnetic source 8 of the rigid portion 3 of the ultrasonic endoscope 1 provided on the bed 15 on which the patient 14 to be inserted is lying; A position detector 19 for supplying a current to the magnetic source 8 to generate a magnetic field and inputting a magnetic field detection signal from the magnetic sensor 16 to calculate the position and orientation of the magnetic source 8; Magnetic field Personal computers to form a 3-dimensional ultrasound image based on the position and orientation of the source 8 to the ultrasound imaging apparatus 13 (hereinafter, referred to as PC) configured with a 20.
[0017]
As shown in FIG. 3, the magnetic field generated by the magnetic source 8 is distorted by the hard part 3 made of a metal member. Therefore, the position detection device 19 corrects the magnetic field detection signal from the magnetic sensor 16 due to the distorted magnetic field with a weighting coefficient stored in advance, and the magnetic field based on the magnetic field detection signal corrected by the correction circuit 21. A position calculation circuit 22 that calculates the position and orientation of the source 8 and a current generator 23 that supplies a current to the magnetic source 8 are configured.
[0018]
Next, the weighting coefficient stored in the correction circuit 21 in advance will be described. For example, before the factory shipment, the ultrasonic diagnostic apparatus 11 has an arm 31 made of a nonmagnetic material as shown in FIG. 4 and an XYZ that moves the arm 31 three-dimensionally by fixing the base end side of the arm 31. The test is performed using a test jig 33 including the stage 32, the weighting coefficient is determined, and the weighting coefficient data is stored in the correction circuit 21.
[0019]
Specifically, as shown in FIG. 5, in step S <b> 1, first, a test source 8 a configured similarly to the magnetic source 8 is disposed at the tip of the arm 31. In addition, this test source 8a is arrange | positioned independently, without being integrated in the hard part 3 which consists of metal members. Then, the test source 8a and the magnetic sensor 16 are connected to the position detector 19, and a magnetic field is generated by supplying a current from the current generator 23 to the test source 8a. At this time, the test source 8a attached to the tip of the arm 31 is sequentially moved by the XYZ stage 32 to a plurality of virtual predetermined lattice points on the three-dimensional space (on the bed 15) of the subject inspection target region. . Note that the position of the virtual grid point is calculated in advance, and the test source 8a can be accurately positioned at the virtual grid point by the XYZ stage 32.
[0020]
In step S 2, the magnetic field generated from the test source 8 a at each virtual lattice point is applied to each voltage signal V by each coil of the magnetic sensor 16._i(I = 1 to 16) is detected and input to the position detection device 19, and the position calculation circuit 22 estimates the position and orientation of the test source 8a via the correction circuit 21 in step S3, and is estimated at each virtual lattice point. The personal computer 20 stores the position data and orientation data corresponding to each virtual grid point as reference data in the internal memory for every virtual grid point. In the correction circuit 21, the initial value “1” is set as the weighting coefficient value to the voltage signal V._iThis time, the voltage signal V_iIs output to the position calculation circuit 22 as it is.
[0021]
Next, in step S4, the test source 8a is removed from the arm 31, the insertion portion 2 of the ultrasonic endoscope 1 is inserted into the arm 31, and the ultrasonic endoscope 1 is placed at the position where the test source 8a is disposed. The tip portion (that is, the hard portion 3) is positioned. Then, the magnetic source 8 disposed in the rigid portion 3 instead of the test source 8a is connected to the position detection device 19, and a current is supplied to the magnetic source 8 from the current generator 23 to generate a magnetic field. Also at this time, the magnetic source 8 is sequentially moved to a plurality of virtual lattice points in space (on the bed 15) by the arm 31 and the XYZ stage 32.
[0022]
In step S5, the magnetic field generated from the magnetic source 8 at each virtual lattice point is applied to each voltage signal V by each coil of the magnetic sensor 16._i(I = 1 to 16) is detected and input to the position detection device 19, and the voltage signal V at each virtual lattice point in the correction circuit 21 in step S <b> 6._iIs stored and the weighting coefficient ω_iVoltage signal V_iIn step S7, the position calculation circuit 22_i× V_iThus, the position and orientation of the magnetic source 8 are estimated. At this time, the correction circuit 21 uses the weighting coefficient ω._iThe initial value “1” is set to the voltage signal V_iIs multiplied by the voltage signal V_iIs output to the position calculation circuit 22 as it is.
[0023]
Subsequently, in step S8, the position data and orientation data estimated at each virtual grid point on the personal computer 20 are used as measurement data, and the measurement data and reference data corresponding to each virtual grid point stored in the internal memory are used. A comparison is made to determine whether or not the difference between all the measurement data at each virtual grid point and the reference data is less than a predetermined error δ. If the difference is greater than or equal to δ, the weighting coefficient ωi varied in step S9 is output to the correction circuit 21. Then, the process returns to step S6.
[0024]
In step S6 again, the weighting coefficient ω changed by the correction circuit 21 is changed._iVoltage signal V_iIs output to the position calculation circuit 22, and in step S7, the position calculation circuit 22_i× V_iThus, the position and orientation of the magnetic source 8 are estimated. Then, the measurement data corrected again in step S8 is compared with the reference data corresponding to each virtual grid point stored in the internal memory, and it is determined whether or not the difference at each virtual grid point is less than a predetermined error δ. Thus, the weighting coefficient ω is obtained by repeating steps S6 to S9._i, And the voltage signal V which is a magnetic field detection signal at the magnetic source 8 in step S10._iEach voltage signal V of the magnetic sensor 16 for calculating the reference data (including the error δ) by_iEach weighting factor ω_iIs determined. Voltage signal V_iThe PC 20 stores each weighting coefficient ω in the internal memory_iIs stored.
[0025]
Weighting coefficient ω determined in this way_iIs stored in the correction circuit 21 as table data of the magnetic sensor 16 in the magnetic field of the magnetic source 8.
[0026]
(Function)
The operation of the present embodiment configured as described above will be described. The insertion portion 2 of the ultrasonic endoscope 1 is inserted into the body cavity of the patient 14 lying on the bed 15, and the ultrasonic endoscope 1 is controlled by the ultrasonic image forming apparatus 13 under the control of the personal computer 10. A three-dimensional ultrasonic image is formed by spiral scanning by driving the ultrasonic transducer 5 and the flexible shaft 6 provided at the distal end and performing radial scanning and inserting and removing the insertion portion 2 of the ultrasonic endoscope 1 and performing linear scanning. .
[0027]
At this time, the position detection device 19 supplies a current from the current generator 23 to the magnetic source 8 provided in the rigid portion 3 made of a metal member of the ultrasonic endoscope 1 and generates a magnetic field by the magnetic source 8. This magnetic field is applied to the voltage signal V by 16 coils of the magnetic sensor 16 arranged at a predetermined position of the bed 15._i(I = 1 to 16) is input to the correction circuit 21 of the position detection device 19.
[0028]
In the correction circuit 21, in order to correct the influence on the magnetic field of the hard part 3 made of a metal member, the detected voltage signal V_i(I = 1 to 16) is multiplied by a previously stored weighting coefficient ωi to obtain ω_i× V_iIs output to the position calculation circuit 22, and the position calculation circuit 22_i× V_iThus, the position data and orientation data of the tip of the ultrasonic endoscope 1 are calculated.
[0029]
Then, the personal computer 20 controls the ultrasonic image forming apparatus 13 to form a three-dimensional ultrasonic image based on the calculated position data and orientation data of the tip of the ultrasonic endoscope 1, thereby The sonic image forming apparatus 13 displays an accurate three-dimensional ultrasonic image on the monitor 12.
[0030]
(effect)
As described above, in the present embodiment, the magnetic field generated from the magnetic source 8 arranged in the rigid portion 3 made of a metal member is applied to the voltage signal V by each coil of the magnetic sensor 16._iThis voltage signal V is detected as (i = 1 to 16)._i(I = 1 to 16) The weighting coefficient ω calculated in advance by the correction circuit 21_iAnd the position calculation circuit 22 corrects the corrected voltage signal ω._i× V_iThus, since the position data and orientation data of the tip of the ultrasonic endoscope 1 are calculated, the magnetic source 8 that distorts the magnetic field emitted from the magnetic source 8 is arranged in the three-dimensional space of the subject inspection target region. Thus, the influence of the hard part 3 made of a metal member can be removed, whereby the ultrasonic image forming apparatus 13 can display an accurate three-dimensional ultrasonic image on the monitor 12.
[0031]
In the above embodiment, a magnetic source that generates a magnetic field is provided at the distal end of the ultrasonic endoscope 1 and is detected by the magnetic sensor. However, a magnetic sensor is provided at the distal end of the ultrasonic endoscope 1 to externally Needless to say, this embodiment can also be applied to the case where a magnetic field is generated from the above.
[0032]
[Appendix 1]
(Additional Item 1-1) A transmission coil that generates a magnetic field and a reception coil that detects a magnetic field generated by the transmission coil, and one of the transmission coil and the reception coil is an ultrasonic endoscope In an ultrasonic diagnostic apparatus comprising a position calculating unit that is disposed at the distal end of the ultrasonic endoscope and calculates a position of the distal end of the ultrasonic endoscope based on a detection signal detected by the receiving coil.
A correction means for correcting a change in the detection signal of the receiving coil due to distortion in a magnetic field generated by a metal part constituting the ultrasonic endoscope is provided.
An ultrasonic diagnostic apparatus.
[0033]
(Additional Item 1-2) The correction unit corrects the detection signal of the reception coil by multiplying the detection signal by a weighting factor.
The ultrasonic diagnostic apparatus according to Supplementary Note 1-1, which is characterized by the above.
[0034]
Incidentally, for example, in Japanese Patent Laid-Open No. 6-261900 and WO96 / 05768, a magnetic source is formed by three coils along three axes orthogonal to the tip of an ultrasonic endoscope or the like, and a magnetic field from this magnetic source is detected. As a result, the position of the tip of the ultrasonic endoscope is calculated and a three-dimensional ultrasonic image is obtained. However, it is difficult to accurately position the coils of the magnetic source on the orthogonal axes. If there is a deviation, the position of the tip of the ultrasonic endoscope cannot be calculated accurately, and there is a problem that the three-dimensional image is distorted.
[0035]
Therefore, an ultrasonic diagnostic apparatus that can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil has an axis deviation will be described.
[0036]
6 to 8 relate to the first embodiment in which the position of the tip of the ultrasonic endoscope can be accurately calculated even if each coil is misaligned. FIG. FIG. 7 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus equipped with the ultrasonic endoscope shown in FIG. 6, FIG. 8 is a block diagram showing the configuration of the magnetic sensor shown in FIG. FIG. 8 is an explanatory diagram for explaining correction data stored in the ROM of FIG. 7.
[0037]
(Constitution)
As shown in FIG. 6, the ultrasonic endoscope 101 has a hard rigid portion 103 at the distal end of the insertion portion 102, and a sheath 104 integrally provided continuously is provided at the distal end of the rigid portion 103. ing. In this sheath 104, an ultrasonic transducer 105 is rotatably connected to a flexible shaft 106 that is inserted through the insertion portion 102 and the rigid portion 103, and an ultrasonic transmission medium 710 is disposed inside the sheath 104. Is filled. Further, the rigid portion 103 includes a magnetic source 108 including two transmission coils 108a and 108b that generate magnetic fields arranged along two orthogonal axes.
[0038]
As shown in FIG. 7, the ultrasonic diagnostic apparatus 111 according to the present embodiment drives the ultrasonic endoscope 101, the ultrasonic transducer 5 and the flexible shaft 6 of the ultrasonic endoscope 101, and performs super An ultrasonic image processing device 113 that forms a three-dimensional ultrasonic image from echo data from the ultrasonic transducer 5 and displays the three-dimensional ultrasonic image on the monitor 112 and a magnetic source 108 of the ultrasonic endoscope 101 are generated. A magnetic sensor 115 (see FIG. 8) including a plurality of receiving coils 114a, 114b, and 114c provided along a plurality of, for example, three orthogonal axes for detecting a magnetic field, and the magnetic source 108 under the control of the ultrasonic image processing device 113 A current generator 116 that supplies a current to generate a magnetic field, and a position detection device that calculates a position of the magnetic source 108 by inputting a magnetic field detection signal from the magnetic sensor 115. 117 and a correction device 119 that corrects the position data calculated by the position detection device 117 with correction data stored in advance in the ROM 118 and outputs the correction data to the ultrasonic image processing device 113. , Based on the corrected position data from the correction device 119, forms a three-dimensional ultrasonic image from the echo data from the ultrasonic transducer 5 and displays the three-dimensional ultrasonic image on the monitor 112.
[0039]
Next, correction data stored in the ROM 118 will be described. FIG. 9 shows a virtual 100 provided in an actual space.^ThreeIt is a cube having lattice points. For example, here, the lattice spacing is 1 mm. At the time of factory shipment, the magnetic sensor 115 is fixed at a predetermined position, and the center of the magnetic source 108 is sequentially arranged at each position of the lattice points. At this time, it is necessary to arrange the center of the magnetic source 108 as accurately as possible at the lattice point. For example, by using a laser range finder or a measuring instrument such as a stage made of a material that does not disturb the magnetic field, the magnetic source The center of 108 is accurately positioned at the lattice point.
[0040]
The center of the magnetic source 108 is the lattice point i (i = 1 to 100).^Three) And the coordinate data R of this lattice point_i(X_i, Y_i, Z_i) Is accurately measured by the above measuring device, and a current is supplied from the current generator 116 to the magnetic source 108 to generate a magnetic field, which is detected by the magnetic sensor 115, and the position detection device 117 is detected by this detection signal. Position data r_i(X_i, Y_i, Z_i) Is calculated.
[0041]
In this way, the coordinate data R accurately measured by the measuring instrument._i(X_i, Y_i, Z_i) Position data r calculated by the position detection device 117 corresponding to_i(X_i, Y_i, Z_i) And coordinate data R at all grid points is stored in the ROM 118._i(X_i, Y_i, Z_i) And position data r_i(X_i, Y_i, Z_i) Stores correction data in a table format as shown in Table 1.
[0042]
[Table 1]

(Function)
Next, the operation of the embodiment configured as described above will be described.
[0043]
The insertion portion 102 of the ultrasonic endoscope 101 is inserted into the body cavity, and the ultrasonic vibration element 10 and the flexible shaft 106 provided at the distal end of the ultrasonic endoscope 101 are driven by the ultrasonic image processing device 113 to perform radial operation. A three-dimensional ultrasonic image is formed by spiral scanning by scanning and inserting / removing the insertion portion 102 of the ultrasonic endoscope 101 and performing linear scanning.
[0044]
At this time, a current is supplied from the current generator 116 to the magnetic source 108 of the ultrasonic endoscope 101 and a magnetic field is generated by the magnetic source 108. The magnetic field intensity is detected by the magnetic sensor 115 disposed at a predetermined position, and the coils of the magnetic source 108 and the magnetic sensor 115 are off-axis from the magnetic field intensity detected by the position detection device 117. The theoretical position data r (x, y, z) is calculated assuming that they are accurately orthogonal, and the position data r (x, y, z) is output to the correction device 119.
[0045]
The correction device 119 reads correction data in the table format (see Table 1) stored in the ROM 118, and the position data r (x, y, z) sequentially output from the position detection device 117 is the correction data in the table format. Which position data r_i(X_i, Y_i, Z_i) To determine the closest position data r_i(X_i, Y_i, Z_iCoordinate data R corresponding to_i(X_i, Y_i, Z_i), Position data r ′ (r ′ = R ′) obtained by correcting position data r (x, y, z) output sequentially._i) To the ultrasonic image processing apparatus 113, and the ultrasonic image forming apparatus 113 displays an accurate three-dimensional ultrasonic image on the monitor 112.
[0046]
At this time, the position data r (x, y, z) is the position data r in the correction data in the table format._i(X_i, Y_i, Z_i) Is the closest to the following equation (1).
[0047]
[Expression 1]

(effect)
As described above, in this embodiment, the magnetic field generated from the magnetic source 108 is detected by the magnetic sensor 115, and the position data r (x, y, z) calculated by the position detection device 117 is corrected by the correction device 119 using the correction data. Coordinate data R_i(X_i, Y_i, Z_i) And corrected accurate position data r ′ (r ′ = R_i) To the ultrasonic image processing device 113, even if each coil of the magnetic source 108 or the magnetic sensor 115 is off-axis, accurate and accurate position data r '(r' = R)._i) Is output to the ultrasonic image processing device 113, an accurate three-dimensional ultrasonic image can be displayed on the monitor 112.
[0048]
In the above embodiment, a magnetic source that generates a magnetic field is provided at the tip of the ultrasonic endoscope 101 and is detected by the magnetic sensor. However, a magnetic sensor is provided at the tip of the ultrasonic endoscope 101, and the external Needless to say, this embodiment can also be applied to the case where a magnetic field is generated from the above.
[0049]
10 and 11 relate to the second embodiment in which the position of the tip of the ultrasonic endoscope can be accurately calculated even if each coil is misaligned, and FIG. 10 shows linear interpolation in the correction apparatus. FIG. 11 is a second explanatory diagram of the estimation equation described with reference to FIG. 10.
[0050]
(Constitution)
The present embodiment is the same as the configuration of the first embodiment that can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil described in FIGS. Since only the correction operation in the correction device 119 is different, only the different points will be described.
[0051]
(Function)
In the embodiment described with reference to FIGS. 6 to 9, the position data r (x, y, z) calculated by the position detection device 117 is converted into the coordinate data R by the correction data by the correction device 119._i(X_i, Y_i, Z_i) To obtain corrected accurate position data r ′ (r ′ = Ri). However, in the present embodiment, position data r at a plurality of lattice points is used._i(X_i, Y_i, Z_i) Is used to estimate accurate coordinate data R ′ (X ′, Y ′, Z ′) of the position data r (x, y, z) sequentially output from the position detection device 117, and this coordinate data R ′. (X ′, Y ′, Z ′) is output to the ultrasonic image processing apparatus 113.
[0052]
Specifically, first, position data in the table format correction data (see Table 1) stored in the ROM 118 with respect to the position data r (x, y, z) sequentially output from the position detection device 117. r_i(X_i, Y_i, Z_i) Position data r of the four lattice points from the closest_i(X_i, Y_i, Z_i). Note that whether or not they are close is determined by the equation (1).
[0053]
Next, the numbers of the four extracted grid points are reassigned as i = 0, 1, 2, and 3 in the order closest to the position data r (x, y, z).
[0054]
Then, the position data r (x, y, z) sequentially output from the position detection device 117 and the extracted position data r of the four lattice points._i(X_i, Y_i, Z_i) (I = 0, 1, 2, 3) and these four accurate coordinate data coordinate data r_i(X_i, Y_i, Z_i) (I = 0, 1, 2, 3), the accurate coordinate data R ′ (X ′, Y ′, Z ′) of the position data r (x, y, z) is estimated.
[0055]
Specifically, the coordinate data R ′ (X ′, Y ′, Z ′) is estimated by linear interpolation according to the following equations (2) to (5).
[0056]
[Expression 2]

[Equation 3]

[Expression 4]

[Equation 5]

Note that the vectors r and r in equation (5)₀, R₁, R₂, R_ThreeIs treated as a 3 × 1 column vector. Therefore, [r₁-R₀    r₂-R₀    r_Three-R₀] Is a 3 × 3 matrix.
[0057]
Then, the obtained coordinate data R ′ (X ′, Y ′, Z ′) is corrected to be accurate position data corresponding to the position data r (x, y, z) sequentially output from the position detection device 117. Is output to the ultrasonic image processing apparatus 113.
[0058]
In general, the value f (r) on the continuous function f defined in the n-dimensional space V is converted into a plurality of known data f (r₀), F (r₁), F (r₂), F (r_Three),..., N + 1 pieces of data f (r_i) (I = 0 to n) can be estimated. At this time, assuming that the estimated value is f ′ (r), the following equations (6) and (7) can be written, and equations (2) to (5) in the present embodiment are expressed by this equation ( 6) and Expression (7) are applied.
[0059]
[Formula 6]

[Expression 7]

Although details of the derivation methods of Expression (6) and Expression (7) are omitted, the outline is as follows. For simplicity, the case of n = 2 will be described.
[0060]
FIG. 10 shows a continuous function f defined on a two-dimensional space (and hence a plane) V. This corresponds to the case of n = 2 in equation (6). Here, a 3 (n + 1) -dimensional space including an axis indicating f is considered. 3 points on V r₀, R₁, R₂Is the corresponding function value f (r₀), F (r₁), F (r₂) And the point P shown in FIG.₀, P₁, P₂It can be expressed as Here, estimating f (r) by linear interpolation means that the point P corresponding to the point r on V is the plane P.₀P₁P₂The estimated value f ′ (r) is obtained on the assumption that it exists above. When this is formulated, the following equations (8) and (9) are obtained.
[0061]
r exists on the plane V:
[Equation 8]

P is plane P₀P₁P₂Exists on:
[Equation 9]

r₁-R₀, R₂-R₀Is linearly independent (when n = 2, r₀, R₁, R₂Assuming that the data does not exist on one straight line)_i= C_i'Is guided. Eventually, by solving Equations (8) and (9) and obtaining f ′ (r), which is one of the components, Equations (6) and (7) are derived, and f (r) is estimated. It becomes possible.
[0062]
Next, in order to confirm the equations (6) and (7), consider a case where a continuous function as shown in FIG. 11 is defined in a one-dimensional space (on the x-axis). Since it is only necessary to set n = 1, in this case, it can be written as follows.
[0063]
[Expression 10]
f ′ (x) = f (x₀) + C (f (x₁) -F (x₀)) ... (10)
Then, substituting equation (7) when n = 1 into equation (10) and deleting C,
[Expression 11]

This is a general linear interpolation equation for continuous functions.
[0064]
(effect)
As described above, in the present embodiment, the position of the tip of the ultrasonic endoscope can be accurately calculated even if the coils described in FIGS. 6 to 9 are misaligned. Although position data corrected in steps equal to or smaller than the lattice spacing could not be obtained, the coordinate data was estimated by linear interpolation, so that fine data smaller than the lattice spacing can be obtained.
[0065]
Further, since fine data equal to or smaller than the lattice interval can be acquired, the number of steps for creating correction data at the time of factory shipment can be reduced by widening the lattice interval and reducing the number of lattice points. Alternatively, it is easy to enlarge the entire lattice and widen the area that can be corrected.
[0066]
FIG. 12 is an explanatory diagram for explaining a lattice point extraction method in the correction apparatus according to the third embodiment, which can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil has an axis deviation. is there.
[0067]
(Constitution)
The present embodiment is the same as the configuration of the first embodiment that can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil described in FIGS. Since only the correction data in the table format stored in the ROM 118 is different from the correction operation in the correction device 119, only the different points will be described.
[0068]
(Function)
In the first and second embodiments, which can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil has an axis deviation, the accurate coordinate data R_i(X_i, Y_i, Z_iThe correction data in the table format shown in Table 1 with constant increments) is stored in the ROM 118. In the present embodiment, the correction data is further converted into position data r calculated by the position detection device 117._i(X_i, Y_i, Z_iThe second correction data in the table format shown in Table 2 with a constant step) is created, and this second correction data is stored in the ROM 118. This second correction data is the position data r having a constant increment._i(X_i, Y_i, Z_iExact coordinate data R)_i(X_i, Y_i, Z_i) Can be estimated and obtained by the method described in the second embodiment, which can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil has an axis deviation. This calculation and work are performed at the time of factory shipment.
[0069]
[Table 2]

By doing so, as shown in FIG. 12, the position data r (x, y, z) having position data surrounding the position data r (x, y, z) sequentially output from the position detection device 117. ) Eight neighboring lattice points (position data r_i(X_i, Y_i, Z_i)) Can be instantaneously extracted from the value of the position data r (x, y, z). For this reason, the operation of extracting four points from the order closest to the position data r (x, y, z) in the second embodiment may be extracted from these eight points, and the operation is simplified. Can do. Other operations are the same as those of the second embodiment.
[0070]
(effect)
As described above, in the present embodiment, eight pieces of position data in the vicinity of position data r (x, y, z) having position data surrounding position data r (x, y, z) sequentially output from position detection device 117 are used. Grid point (position data r_i(X_i, Y_i, Z_i)) Can be instantaneously extracted from the value of the position data r (x, y, z), the distance | r−r between the position data for all grid points._iIt is possible to easily extract four points from the order closest to the position data r (x, y, z) without calculating |. For this reason, it is possible to dramatically improve the calculation speed for estimating the accurate coordinate data R corresponding to the position data r (x, y, z) sequentially output from the position detection device 117.
[0071]
[Appendix 2]
(Additional Item 2-1) A transmission coil that generates a magnetic field and a reception coil that detects a magnetic field generated by the transmission coil, and either one of the transmission coil and the reception coil is an ultrasonic endoscope. A position calculating means for calculating the position of the distal end of the ultrasonic endoscope based on a detection signal detected by the receiving coil, and at least one of the transmitting coil and the receiving coil is orthogonal in axis. In the ultrasonic diagnostic apparatus which is a coil group composed of a plurality of coils,
A correction means for correcting a positional shift caused by the axial shift of the coil group is provided.
An ultrasonic diagnostic apparatus.
[0072]
(Additional Item 2-2) A recording unit that records correction data for correcting the positional deviation,
The correction unit corrects the misalignment based on the correction data.
The ultrasonic diagnostic apparatus according to Supplementary Note 2-1, which is characterized by the above.
[0073]
(Additional Item 2-3) The correction data is data indicating a correspondence between the position data calculated by the position calculation unit and an actual measurement value measured separately from the position data.
The ultrasonic diagnostic apparatus according to Additional Item 2-2, wherein:
[0074]
(Additional Item 2-4) The correction unit corrects the position data calculated by the position calculation unit using a value obtained by linear interpolation.
The ultrasonic diagnostic apparatus according to Additional Item 2-2 or 2-3, wherein:
[0075]
【The invention's effect】
As described above, according to the ultrasonic diagnostic apparatus of the present invention, the correction means corrects the change in the detection signal of the receiving coil due to distortion in the magnetic field generated by the metal parts constituting the ultrasonic endoscope. There is an effect that the influence of the distortion of the magnetic field due to the metal parts constituting the mirror is eliminated, and the accurate position and orientation of the tip of the ultrasonic endoscope can be calculated.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a distal end of an ultrasonic endoscope according to an embodiment of the present invention.
2 is a configuration diagram showing the configuration of an ultrasonic diagnostic apparatus including the ultrasonic endoscope of FIG. 1;
3 is a configuration diagram showing the configuration of the position detection device of FIG. 2;
4 is a first explanatory diagram illustrating weighting coefficients stored in advance in the correction circuit of FIG. 3;
FIG. 5 is a second explanatory diagram illustrating weighting coefficients stored in advance in the correction circuit of FIG. 3;
FIG. 6 is a cross-sectional view showing the configuration of the distal end of the ultrasonic endoscope according to the first embodiment that can accurately calculate the position of the distal end of the ultrasonic endoscope even if each coil has an axis shift. Figure
7 is a configuration diagram showing a configuration of an ultrasonic diagnostic apparatus including the ultrasonic endoscope of FIG.
8 is a configuration diagram showing the configuration of the magnetic sensor of FIG.
9 is an explanatory diagram for explaining correction data stored in the ROM of FIG. 7;
FIG. 10 illustrates an estimation formula by linear interpolation in a correction apparatus according to a second embodiment that can accurately calculate the position of the tip of an ultrasonic endoscope even if each coil has an axis shift. First explanatory diagram
11 is a second explanatory diagram of the estimation formula described with reference to FIG. 10;
FIG. 12 is an explanatory diagram for explaining a lattice point extraction method in the correction apparatus according to the third embodiment that can accurately calculate the position of the tip of the ultrasonic endoscope even if each coil has an axis shift;
[Explanation of symbols]
1 ... Ultrasound endoscope
2 ... Insertion section
3 ... Hard part
4 ... Sheath
5 ... Ultrasonic transducer
6 ... Flexible shaft
7 ... Ultrasonic transmission medium
8 ... Magnetic source
11 ... Ultrasonic diagnostic equipment
12 ... Monitor
13. Ultrasonic image forming apparatus
16 ... Magnetic sensor
19 ... Position detecting device
20 ... PC
21 ... Correction circuit
22: Position calculation circuit
23 ... Current generator

Claims (8)

A transmission coil that generates a magnetic field;
A receiving coil for detecting a magnetic field generated by the transmitting coil, and
Position information calculation in which one of the transmission coil and the reception coil is arranged at the distal end of the ultrasonic endoscope, and the positional information of the distal end of the ultrasonic endoscope is calculated from the detection signal detected by the reception coil In an ultrasonic diagnostic apparatus comprising means,
Detection that generates detection signal correction information for correcting the detection signal based on the detection signal detected by the reception coil when the distal end of the ultrasonic endoscope is disposed at a predetermined position of a virtual point in space. Correction information generating means;
Detection signal correction means for correcting the detection signal output from the reception coil using the detection signal correction information;
An ultrasonic diagnostic apparatus comprising: Virtual point position information, which is the position information calculated by the position calculation means when the distal end of the ultrasonic endoscope is arranged at a predetermined position of the virtual point, or estimation by interpolating the virtual point position information Storage means for storing at least one of the virtual point estimated position information which is position information;
  Position information correction means for correcting the position information calculated by the position calculation means using the virtual point position information or the virtual point estimated position information stored in the storage means;
  The ultrasonic diagnostic apparatus according to claim 1, further comprising: The virtual point position information, which is the position information calculated by the position calculation means when the distal end of the ultrasonic endoscope is arranged at a predetermined position of the virtual point, and the virtual when the virtual point position information is obtained Storage means for associating and storing virtual point estimated position information, which is estimated position information obtained by interpolating and estimating a known position of a point;
  Position information correction means for correcting the position information calculated by the position calculation means using the associated virtual point position information and the virtual point estimated position information stored in the storage means;
  The ultrasonic diagnostic apparatus according to claim 1, further comprising: The interpolation of the known position calculated by the position calculation means by the position information correction means is interpolation by linear interpolation.
  The ultrasonic diagnostic apparatus according to claim 3. The virtual points on the space are a plurality of lattice points virtually arranged on the space.
  The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, wherein: The interval between the plurality of lattice points is a constant interval.
  The ultrasonic diagnostic apparatus according to claim 5. The virtual point estimated position information is obtained when the virtual point position information is obtained by using the position information calculated by the position calculating means when the distal end of the ultrasonic endoscope is arranged at a plurality of known positions. It is estimated information estimated by interpolating the known position of the virtual point
  The ultrasonic diagnostic apparatus according to any one of claims 2 to 4, wherein the apparatus is an ultrasonic diagnostic apparatus. The detection signal correction unit performs the correction by multiplying the detection signal of the reception coil by a weighting factor based on the detection signal correction information.
  The ultrasonic diagnostic apparatus according to any one of claims 1 to 7, wherein

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