JP2004150961A - Optical measuring device and optical measuring method - Google Patents

Abstract

Provided is an optical measurement device that can be used at home by imaging measurement results and simplifying the device. A probe device for image measurement 1 according to the present invention includes a position detection unit 4. . Thus, by scanning the probe composed of the light emitting unit 2 and the light receiving unit 3 along the subject 14, the intensity of the transmitted scattered light inside the subject 14 is measured, and at the same time, the probe of the probe is The position can also be detected. Therefore, the intensity of the transmitted scattered light at each measurement position and the measurement position are continuously stored in the storage unit 7, and by combining them, the detection result can be imaged. Further, since the probe is scanned, the detection result can be imaged even with a small number of light emitting elements 10 and light receiving elements 12, and the apparatus can be downsized.
[Selection diagram] Fig. 1

Description

【００６７】
ここで、Ｍは３×２の行列であり、各要素の値は、使用する発光素子の波長によって異なる。また、記憶部８には、離散化された各点での時刻１での計測量Ｓ１（１）およびＳ２（１）、および計測量Ｓ１（ｔ）の平均値とＳ２（ｔ）の平均値、その点をプローブが通過した回数が貯えられている。記憶される値の更新は、新しく取得した計測量と、記憶部８に貯えられている各計測量の平均値と、通過回数とから新しい３つの計測量の平均を算出する。計測量から算出された光学濃度の変化から算出された３つの変化量が、表示部９に出力され、表示部９のモニターに表示される。表示方法については、従来公知の種々の方法を適用することができる。
【００６８】
続いて、図１の画像計測用プローブ装置１を用いた、データ処理について説明する。このプローブ１は、位置検出部４によりプローブ１の位置検出を行う。それと同時に、発光制御部１１からの信号に応じて、２つの受光素子１０ａおよび１０ｂを交互に発光させ、受光部３により透過散乱光を受光する。位置検出部４により得られた位置検出情報と、受光部３で検出した近赤外分光情報は、信号線によって実時間にコンピュータなどのデータ処理部８に送られ、信号処理される。データ処理部８で信号処理された結果は、コンピュータのモニターなどの表示部９に表示される。
【００６９】
プローブ１は、ユーザーの手によって自由に操作でき、被検体（例えば人体）上のあらゆる部分を走査できる。これにより、ユーザーは、表示部９に写し出された計測画像を見ながら、被検体上を走査できる。また、場合によっては、プローブ１を固定して、特定の部分の透過散乱光の強度を長時間測定し、その部分における光強度の経時的変化を観測することができる。
【００７０】
以上のように、本発明にかかる光計測装置は、生体などの被検体に近赤外光を照射し、その透過・散乱光を測定することにより、無侵襲的に被検体内の情報を取得することができる。また、簡易な構成で被検体内の情報を画像表示することができる。
【００７１】
なお、図１では、２つの発光素子１０ａおよび１０ｂを備えているが、発光素子１０の数は特に限定されるものではない。また、受光素子１２の数も特に限定されるものではない。すなわち、プローブを構成する素子の数は特に限定されない。言い換えると、本発明の光計測装置は、単チャンネル型のものであってもよいし、マルチチャンネル型のものであってもよい。
【００７２】
本発明において、より正確に被検体上を走査するためには、図４に示されるように、プローブ１５を補助器具に取り付けて可動式としてもよい。図４では、外枠１８に一対のｘ方向移動用レールと１６と、それに垂直な方向にｙ方向移動用レール１７と、プローブ保持部１９とを備えている。プローブ１５は、プローブ保持部１９に固定されている。これにより、プローブ１５は、ｘ方向およびｙ方向の２次元方向に走査することができる。その結果、２軸（ｘ方向およびｙ方向）の移動レールから検出された精密なプローブ１５の位置が検出される。それゆえ、空間的に均一な測定や長時間の変化を観測できる。また、各移動用レール１６および１７にモーターを取り付けてプローブ１５を自動的に移動させれば、空間的な光計測が自動化される。
【００７３】
なお、上記の説明では、１組の発光部２と受光部３とを備えた画像計測用装置１について説明したが、発光部２と受光部３とを複数組備えるものであってもよい。複数組用いれば、複数箇所で計測できるので、測定時間の短縮や分解能が向上する。ただし、発光部２と受光部３との組を多く備えると、素子の数も増え、装置の大型化およびコスト高を招来する。このため、発光部２と受光部３とを複数組備える場合であっても、その数は少ないほうがよい。
【００７４】
複数組の発光部２と受光部３とを複数組備える場合には、例えば、図５に示すように、発光素子１０ｘおよび受光素子１２ｘと、発光素子１０ｙおよび受光素子１２ｙとを直交配置することが好ましい。
【００７５】
図５（ａ）は、２波長の発光素を含む発光素子１０と受光素子１２とによって、図示しない光吸収物体を、プローブ１５を走査することにより検出した結果を示す図である。横軸は発光素子１０と受光素子１２の中心が光吸収物体の中心にある場所を原点とした時のプローブ１５のｘ方向の移動量であり、縦軸はそのｙ方向の移動量である。図５（ａ）のグラフは、１組の発光素子１０ｘと受光素子１２ｘとを備えたプローブ１５によって被検体上を走査することにより、微小な光吸収物体を測定した時の、プローブ１５の中心位置の変化に対する出力画像、すなわち、点像応答関数その中心プロファイルとを示している。この出力画像の濃淡は、光吸収物体による光学濃度変化を示しており、濃度が濃いほど光学濃度変化も大きい。ここでは、グラフの中心は光吸収物体が、発光素子１０と受光素子１２との中心にある場合であり、グラフの中心ほど光学濃度変化が大きくなっている。
【００７６】
一方、図５（ｂ）は、直交配置された２組の発光素子１０ｘ、１０ｙと受光素子１２ｘ、１２ｙとによって、図示しない光吸収物体を検出した結果を示す図である。図５（ｂ）の点像応答関数と図５（ａ）の点像応答関数とを比較すると、２組の発光素子１０ｘ、１０ｙと受光素子１２ｘ、１２ｙを用いた図５（ｂ）の方が、図５（ａ）の空間的なプロファイルに比べて、中心付近の検出値が大きくなっている。これは、２つの受光素子１２ｘ、１２ｙからの出力が重ねあわされるためである。出力画像も同様に、図５（ｂ）の方が、特に中心付近の出力が大きくなっている。このように、２組の発光素子１０ｘおよび１０ｙと、受光素子１２ｘおよび１２ｙとを垂直配置することにより、光吸収物体の検出能を向上できる。
【００７７】
図５（ａ）および図５（ｂ）に示すような点像応答関数は、任意の関数で変換してもよい。これにより、光吸収物体の検出能力を一層向上させることができる。また、ユーザーは、その信号処理のための関数のパラメータを適応的に変えながら、被検体の光吸収物体を見つけやすい信号処理カーブを変更することもできる。具体的には、図５（ａ）（ｂ）は、中央に微小な光吸収体がある場合に検出される光学濃度変化を示している。上記「光吸収物体の検出能力を向上」とは、図５（ａ）（ｂ）で黒く表される領域の面積を狭くするような処理を行うことを意味している。ユーザーは、画素値の閾値処理の傾きと中心、あるいは、画像の輪郭を除去するような画像処理（つまり、画像の明るさ、コントラスト、ダイナミックレンジを変更する処理、先鋭化処理）を組み合わせて光吸収体を見つけやすいように信号処理のカーブを変更することができる。光吸収体の深さ、被検体の光学特性によって、最適な信号処理は異なることが予想されるため、ユーザーが信号処理カーブを見ながら、最も見やすい画像を得るように調整することができる。
【００７８】
例えば、図５（ａ）に示される出力画像に対して、図６（ａ）に示すように、所定以上の吸光度の変化があった場合にのみ出力するような関数で吸光度変化（光学濃度変化）を変換してもよい。これにより、図６（ｂ）に示すように、光吸収物体の位置をさらに空間的に絞り込むことができる。すなわち、光吸収物体の検出能を上げることができる。ただし、各方向での光吸収物体の位置を絞り込む大きさが異なっている。
【００７９】
一方、図５（ｂ）に示される出力画像に対して、図７（ａ）に示すように、受光素子１２ｘにより検出した吸光度の変化と、受光素子１２ｙにより検出した吸光度の変化とが特に大きい領域を出力するような関数（すなわち、図５（ｂ）の出力画像のうち、受光素子１２ｘおよび１２ｙの出力画像が重なっている領域のみを出力するような関数）で吸光度変化（光学濃度変化）を変換してもよい。これにより、図７（ｂ）に示すように、光吸収物体の位置をほぼ円形に絞り込むことができる。すなわち、図６（ｂ）の場合よりも、より一層光吸収物体の検出能を上げることができる。さらに、絞り込んだ領域の形状はほぼ円形であるため、各方向での光吸収物体の位置を絞り込む大きさもほぼ等しい。
【００８０】
また、図５（ｂ）の出力画像は、図８に示すように、光吸収物体が発光素子１０ｘまたは１０ｙ、または、受光素子１２ｘまたは１２ｙの直下に近い場合（すなわち、光吸収物体が被検体の表面に近い位置に場合）に見られる、大きな吸光度変化のみを出力するような関数で変換してもよい。光吸収物体が、発光素子１０ｘまたは１０ｙや受光素子１２ｘまたは１２ｙの直下の浅い位置にあれば、大きな吸光度変化が検出されることになる。したがって、この大きな吸光度変化が検出された時のみ大きな出力とすることにより、被検体の表面から浅い位置にある光吸収物体のみを分離することができる。なお、１組の発光素子と受光素子とでは、いかなる関数を選択して分離することができなかった。
【００８１】
このように、２組の発光素子１０ｘおよび１０ｙと受光素子１２ｘおよび１２ｙを垂直配置することにより、１組の発光素子１０ｘと受光素子１２ｙの場合よりも、光吸収物体の領域を絞り込むことができ、さらに、被検体の表面に近い光吸収物体のみを検出することもできる。
【００８２】
以上のように、本発明の光計測装置は、生体などの被検体に対して、近赤外領域で中心波長の異なる光を照射し、被検体を透過した透過光を検出して得られた信号を処理することにより被検体の内部の情報を画像表示できる。
【００８３】
より詳細には、プローブを人体表面に沿って走査して、発光および受光のタイミングを合わせて位置検出部によって位置検出情報を得る。さらに、各点毎の光強度を検出して多数枚数重ねることにより、高分解画像が得られる。
【００８４】
このように、本発明の光計測装置は、被検体に光を照射し、その透過散乱光の強度を検出する光センサー（プローブ）と、プローブの位置を検出する位置検出センサー（位置検出手段）とを統合している。
【００８５】
また、本実施形態の光計測装置によれば、少ない発光素子および受光素子で、広い領域の測定が可能となる。これにより、装置を小型化でき、別の器具に取り付けて同時に使用することができる。例えば、内視鏡やカテーテルなどの別の器具に、この光計測装置を取り付けることにより、患部の代謝状態を監視しながら治療処置を施すことができる。
【００８６】
さらに、本発明の光計測装置は、容易に測定結果のデータを保存することができる。その結果、測定結果が画像情報として保存された場合、画像ファイリングソフトを使用すれば、その画像情報を閲覧しやすくなり、データの保存も容易になる。また、検査をする際に、予め日付や患者名を記載したマークを皮膚に貼っておき、そのマーク情報の取得結果も同時に記憶することにより、患者と測定データとを取り違える危険も回避される。
【００８７】
なお、表１に示すように、マルチチャンネル型プローブと、スキャナ型プローブと、光センサー型プローブとでは特徴が異なる。本発明の光計測装置は、いずれのプローブにも可能であるので、被検体の種類や、目的に応じて、プローブの種類を変更すればよい。
【００８８】
【表１】

【００８９】
スキャナ型プローブは、マルチチャンネル型プローブと比較すると以下の重要な特徴を有する。
▲１▼空間分解能が向上する
スキャナ型プローブでは、多様な方向からスキャンできるので、吸光度の吸収変化した部位（すなわち光吸収物体の位置）を絞り込むことができる。これに対して、マルチチャンネル型（例えば固形センサー型）プローブでは、発光素子と受光素子とが数ｃｍ程度離れているため、例えば、被検体の透過散乱光が変化した場合（例えば、脱酸素化ヘモグロビンと酸素化ヘモグロビンとの濃度変化、および総血量が変化した場合）、発光素子と受光素子との間にその部位があることが分かる。しかし、それ以上、その部位の場所を特定することができない。こののように、スキャナ型プローブは、マルチチャンネル型プローブよりも、空間分解能が高い。
▲２▼深さ感度を有する
スキャナ型プローブでは、光吸収物体の深さに応じて得られる画像が異なる。これにより、光吸収物体の深さも検出することができる。
▲３▼測定結果の空間的均質性を有する
本発明のスキャナ型プローブは、１組の発光素子と受光素子とにより、光吸収物体の検出を行うため、各素子の違いによる測定結果のばらつきを防止できる。すなわち、高精度の測定結果が得られる。これに対して、マルチチャネル型プローブでは、発光素子と受光素子とを多数使用して光吸収物体の検出を行うため、各素子の違いによって測定結果がばらついてしまう。すなわち、スキャナ型プローブよりも測定結果の精度が劣る。
▲４▼測定結果に応じて探索できる
ユーザーは、測定結果がリアルタイムで現われる画面を見ながら吸光度の測定ができる。したがって、わずかな吸光度の吸収変化した部位が観測されたばあいであっても、多様な方向からスキャンすることにより、その部位が病変であるか否かを判別できる。また、明らかに吸光度の吸収変化が現われなければ、速やかに別の部位を探索できる。これにより、計測時間が短縮できる。
【００９０】
なお、マルチチャンネル型のプローブの最大の特徴は、多くの部位を同時に測定できるので、高速測定が可能であること、さらに、被検体に応じたプローブ配置を行うことができることにある。
【００９１】
（３）本発明の光計測装置の特徴・利点
▲１▼人体などの被検体に近赤外線領域の光を照射し、その透過散乱光の分光スペクトルにより生体機能などを非侵襲的に測定できる（血液中のヘモグロビンが酸素化−脱酸素化状態によりその吸光度が波長依存性を示すことを利用している。）。
【００９２】
▲２▼身体活動における筋の代謝状態による運動機能の測定、リハビリの評価が可能である。さらに、装置を構成する素子も少なく安価に製造できるため、例えば、家庭内で肩こりの測定などを行うことが可能である。
【００９３】
▲３▼癌（特に乳癌）検診や脳機能測定に応用し得る
乳がんの患者数は年々増えており、近い将来には乳がんが女性で最も多いがんとなると言われている。がん治療においては、初期の段階で腫瘍を検出することが、非常に有効である。最近、近赤外光を使って初期のがんを非侵襲で検出する方法が研究されている。
【００９４】
この方法は、ヘモグロビンと酸素との結合状態に応じて、ヘモグロビンの吸収スペクトルが変化することを利用している。すなわち、近赤外領域において、ヘモグロビンの吸収スペクトルが酸素化・脱酸素化の状態によって変化するため、近赤外光を用いてヘモグロビンの濃度変化が測定できる。そして、得られたヘモグロビン変化から、生体組織の代謝状態を非侵襲で調べることができる。
【００９５】
腫瘍組織は、代謝が活発であるため、近赤外分光イメージングシステム（本発明の光計測装置）を利用して胸の腫瘍を検出できる可能性がある。胸の腫瘍を可視化できるようなシステムが個人向けに（できれば安価で）実現できれば、初期の乳がんを検出するための自己検診に有効である。
【００９６】
一般的に、早期の乳癌は２ｃｍまでと言われているが、この段階では自覚症状がほとんどない。触診によってしこりを発見するためには、２．６ｃｍ以上の大きさが必要である。したがって、乳癌の早期発見・早期治療のためには、２ｃｍ以下のしこりを発見することが重要である。
【００９７】
本発明の光計測装置は、生体を透過・散乱した光の強度を検出することにより、光吸収物質（この場合しこり）の存在を確認するものである。したがって、従来のように触診では発見することのできなかった、早期の乳癌であっても、確実に発見することができる。そのため、乳癌の早期発見・早期治療に役立つ。
【００９８】
本発明は上述した実施形態の構成に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態の構成にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。
【００９９】
【実施例】
以下、実施例に基づいて本発明をより詳細に説明する。なお、本発明はこれに限定されるものではない。
【０１００】
なお、以下の実施例では、図１２に示すように、散乱体２０の入った容器に光吸収物体２１を入れ、プローブ１５を走査することにより光吸収物体２１の画像を取得する実験を行った。
【０１０１】
また、プローブ１５としては、発光素子として２波長（７６０ｎｍと８４０ｎｍ）の発光ダイオード（以下「ＬＥＤ」と称する）と、受光素子としてアンプ付きのシリコンフォトダイオード（以下「ＰＤ」と称する）とからなる光プローブを使用した。実際の装置として使用する場合に、皮下脂肪よりも深い位置での吸収の変化を検出できるようにするため、ＬＥＤとＰＤとの距離を３０ｍｍに設計し、散乱体の表面から１５ｍｍまでの深さに光吸収物体を設置した。また、実施例１〜６は、ＬＥＤとＰＤとの組を１組用い、実施例７はＬＥＤとＰＤとの組を２組用いた。
【０１０２】
〔実施例１〕（散乱体中のフォトン経路）
本実施例では、散乱体中のフォトン（光子）経路を調べる実験を行った。通常、生体組織などの強い散乱体中を光が伝搬する経路を調べるために、モンテカルロ法がよく使われる。このモンテカルロ法は、図１１に示すように、フォトン（光子）の軌跡を追跡するものである。例えば、極方向θでアジムス方向φの２点の間の光路長Ｌは、次の式（４）で算出できる。なお、図１１中の破線は、ｘｙ平面の射影成分を示している。
【０１０３】
【数２】

【０１０４】
ここで、Ｒ_１、Ｒ_２、Ｒ_３は、０と１との間で一様な出現確率をもつ疑似乱数であり、ｍｔ＝ｍｓ＋ｍａは吸収計数の総量、ｆ（ｑ）は散乱体の位相関数ｐ（ｑ）の累積母関数である。
【０１０５】
ｉ番目の相互作用において吸収されるエネルギー（Ｅｉ）は、再帰的に表される。相互作用の後吸収されるエネルギーは、重み係数ｍａ／ｍｔを用いて、Ｅ_ｉ＋１＝（ｍａ／ｍｔ）Ｅ_ｉで表される。散乱係数ｍｓ、 吸収係数ｍａ 非等方係数ｇの典型値は、それぞれ、１０．０ｍｍ^−１、０．１ｍｍ^−１、０．９である。
【０１０６】
これに基づいて、フォトンの移動経路を、ＬＥＤとＰＤとの間隔を変えて算出した。その結果、フォトン経路がＬＥＤとＰＤとの間隔のおよそ半分の深さまで分布することがわかった。
【０１０７】
図１３および図１５は、ＬＥＤとＰＤとの距離が３０ｍｍの場合についてモンテカルロシミュレーションを行って得られたフォトン経路を示した図である。図１３は、散乱体の深さ方向（ｚ方向）へのフォトン経路を示した図であり、図１５は、散乱体の平面方向（ｙ方向）へのフォトン経路を示した図である。ここではＰＤの受光面積を、後述の実施例で用いたＰＤと同じく、１０ｍｍ×１０ｍｍとした。その結果、フォトン経路は表面から１７ｍｍの深さ（ｚ方向）まで分布した。
【０１０８】
また、光吸収物体の深さ方向（ｚ方向）とＰＤによる被検体の透過散乱光の受光量との関係を調べた。その結果を図１４に示す。光吸収物体は１辺５ｍｍの立方体であり、ＬＥＤとＰＤとの中点に配置している。図１４に示すように、光吸収物体が被検体の表面に近いときには、ＰＤに入射するはずのフォトンの多くが光吸収物体により吸収された。一方、吸収体が１７ｍｍより深い場合には、ＰＤに入射するはずのフォトンのほとんどが吸収体に当たらずにＰＤに入射された。
【０１０９】
〔実施例２〕ファントムによる実験
本実施例では、図１２における散乱体２０として牛乳：水＝１：９を使用し、ここではプローブを走査するかわりに光吸収物体２１として光吸収率が大きい１つのゴム球（半径３．０ｍｍ）を使用した。ゴム球には針金を取り付け、自動ステージにより移動させた。
【０１１０】
このような条件で、ゴム球を５ｍｍ、１０ｍｍ、１５ｍｍの深さに調整し、それぞれ発光素子と受光素子を中心としてｘ方向、ｙ方向６０ｍｍの範囲を移動させた。その結果、図１６および図１７に示すように、各深さのゴム球を画像化して検出することができた。なお、図１６（ｂ）は、ｙ＝３０ｍｍにおけるｘ方向の移動距離に対する受光強度の変化を記録した図である。このように、本実施例により、散乱体中の光吸収物体による光強度の変化を検出することにより、光吸収物体を画像化できることが明らかとなった。
【０１１１】
〔実施例３〕ファントム（疑似生体物質）による実験
図１８に本実施例で使用した実験装置の構成を示す。散乱体として酸化チタンを混入したエポキシ樹脂としファントムを作製した。プローブの走査は、図示しない２次元移動ステージ（以下Ｘ−Ｙステージと称する）を用い、ｘ方向に６０ｍｍまで行った。なお、このＸ−Ｙステージの位置決め精度は、各軸０．０２５ｍｍである。Ｘ−Ｙステージのコントローラを経由して、移動距離を記録した。なお、ゴム球の配置は、表面から５ｍｍ、１０ｍｍ、１５ｍｍの深さに吸収体を固定し、プローブをｘ方向に１００ｍｍ走査してゴム球の画像を取得する実験を行った。
【０１１２】
図１９は、プローブを走査した各位置における受光強度の結果を示した図である。図１９に示すように、受光強度の３つのボトムの間隔がゴム球の間隔と一致した。すなわち、本実施例のプローブによって、散乱体中の光吸収体の吸光度変化を検出できることが明らかとなった。
【０１１３】
このように、本実施例のようにファントムを作成した場合であっても、散乱体に入射され、散乱された後、ＰＤによって光強度が受光された。なお、受光信号は受光部に内蔵のアンプ（増幅器）によって増幅された。増幅された信号は、Ａ／Ｄ変換ボードを介して、Ｘ−Ｙステージの位置と一緒にＰＣ（データ処理部）に保存された。
【０１１４】
〔実施例４〕２次元面方向での測定
実施例３で用いたプローブをファントム上で１００ｍｍ×１０ｍｍの範囲で動かした。ゴム球の各位置における受光強度を記録した。図２０は、受光強度を濃淡で示して得られた画像である。受光強度が低い点を暗く示す。すなわち、暗い領域がゴム球の位置に対応する。受光強度は、吸収体の水平方向の位置と深さに依存する。したがって、吸光度変化を表す画像を１チャンネルの移動によって得られることが明らかとなった。
【０１１５】
〔実施例５〕ＰＣ用マウスによってプローブの位置を検出するための予備実験プローブの位置（測定位置）の検出を行うために、ＰＣ用マウスを適用可能かどうか検討した。図２１に示すように、プローブをＰＣ用マウスに取り付け、マウスのカーソルの位置を、実際のプローブの位置に換算した。このプローブを用いて、被検体として、アルファベットの「Ｍ」という文字の検出を行った。その結果、図２２に示すように、マウスに取り付けたプローブを用いて、被検体の「Ｍ」を検出することができることが明らかとなった。すなわち、マウスによってプローブの位置検出を行うのと同時に、被検体の吸光度の測定も行うことができる。
【０１１６】
〔実施例６〕
ＰＣ用マウスを用いてプローブの移動量を検出する方法の可能性を散乱体を用いた実験で調べた。ＰＣマウスに取り付けたプローブを用いる以外は、実施例３と同様にして行った。ファントムの上をプローブが動くことに伴って、マウスカーソルがＰＣ座標の上で動く。プローブが動いた距離に基づいて、実空間の座標でプローブが動いた距離をＰＣ座標でマウスカーソルが動いた距離に換算した。図２３は各位置での受光強度を示したものである。ＰＣ用マウスの信号によって得られたプロットが、実施例３のＸ−Ｙステージの信号で得られた曲線と一致している。このように、ＰＣ用マウスを用いた走査型プローブを近赤外分光イメージングに応用できることが明らかとなった。
【０１１７】
〔実施例７〕直交配置された２組の発光部・受光部を備えたプローブでの実験実施例２と同様な実験装置で直交に配置された２組のＬＥＤとＰＤプローブを用いて実験を行った。吸収物体を深さ１０ｍｍで５０ｍｍ×５０ｍｍの範囲を移動させた。その結果、図２４（ａ）と図２４（ｂ）に示すそれぞれの検出器の出力からその重なりを利用して、図２４（ｃ）に示すように、より吸光度変化の部位を絞り込むことが可能となった。すなわち、検出精度の向上が可能となった。
【０１１８】
【発明の効果】
以上のように、本発明にかかる光計測装置は、被検体に光を照射する発光素子と透過散乱した光を検出する受光素子とを少なくとも１組含むプローブにより、被検体の透過散乱光の強度を検出する光計測装置において、上記プローブの位置を検出する位置検出手段を備えていることを特徴としている。
【０１１９】
それゆえ、被検体上に沿ってプローブを走査して各位置における光強度を測定した結果と、位置検出手段によるプローブの位置情報とを組み合わせることにより、測定結果を画像化することができるという効果を奏する。言い換えると、被検体の測定位置と、その位置における透過散乱光の強度との経時的な変化を連続的に重ねあわすことにより、画像化することができるという効果を奏する。
【０１２０】
さらに、プローブを走査して測定結果を画像化するので、発光素子および受光素子は、多数必要としない。したがって、１組の発光素子および受光素子からなる単チャンネル型プローブであっても、測定結果を画像化することができる。それゆえ、本発明の光計測装置は、多数の発光素子と受光素子とを必要としないので、装置が簡素化されている。すなわち、装置の費用を削減することができるので、安価な光計測装置を提供できるという効果を奏する。
【０１２１】
本発明の光計測装置において、上記プローブと上記位置検出手段とが一体構造であってもよい。
【０１２２】
それゆえ、小型・軽量の光計測装置を提供することができるという効果を奏する。また、従来の装置は大型の装置であったため、研究所や大病院でのみでしか測定できなかった装置を、家庭内にも提供できるという効果を奏する。
【０１２３】
本発明の光計測装置は、上記プローブを移動させる移動手段を備えていてもよい。
【０１２４】
それゆえ、移動手段によって自動的にプローブが被検体上を走査させることができる。
【０１２５】
本発明の光計測装置において、上記発光素子は、中心波長の異なる２波長以上の近赤外領域の光を照射するものであってもよい。
【０１２６】
近赤外領域の光は、生体を透過しやすい。このため、被検体が生体である場合には、発光素子が被検体に照射する光は、近赤外の光であることが好ましい。また、近赤外領域の光を用いれば、無侵襲、非破壊の計測が可能である。さらに、近赤外領域の光を用いれば、測定操作が容易となりルーチン分析に適している。
【０１２７】
したがって、上記の構成によれば、たとえ被検体が生体であっても、安全かつ容易に、しかも低拘束の光計測装置を提供することができるという効果を奏する。
【０１２８】
さらに、上記発光素子は、近赤外領域の光であって、中心波長の異なる２波長以上の光を照射することが好ましい。被検体の透過散乱光の強度を測定する際には、測定対象とする物質以外にも、発光素子からの光を吸収する物質が存在することもある。このような物質が存在すれば、測定の妨げになり、検出精度も低いものとなる。そこで、測定の妨げになるような波長を避け、２波長以上の光を照射すれば、目的とする物質のみの光強度を精度よく計測できるという効果を奏する。
【０１２９】
上記近赤外領域の光においては、波長７００ｎｍ〜９００ｎｍの範囲内の波長の光を照射することが好ましい。波長７００ｎｍ以下では、生体による光の散乱が大きくなり、波長９００ｎｍ以上では、水による吸収が大きくなる。このため、被検体の透過散乱光を検出するときの妨害となる。したがって、波長７００ｎｍ〜９００ｎｍの範囲内とすることにより、この妨害を防ぎ、精度よく被検体の透過散乱光を検出できるという効果を奏する。
【０１３０】
また、本発明において、上記プローブは、直交配置された上記発光素子と上記受光素子との組を２組以上含んでいてもよい。
【０１３１】
それゆえ、発光素子と受光素子とを垂直配置することにより、光吸収物体の検出能を向上できるという効果を奏する。また、１組の発光素子と受光素子の場合よりも、光吸収物体の領域を絞り込むことができ、さらに、被検体の表面に近い光吸収物体のみを検出することもできるという効果を奏する。
【０１３２】
本発明において、上記プローブは、１個以上の発光素子と、１個以上の受光素子とを含んでいればよい。
【０１３３】
それゆえ、発光素子または受光素子の数を減らすことができ、一層光計測装置を小型化することが可能となるという効果を奏する。
【０１３４】
また、本発明にかかる光計測方法は、以上のように、被検体に光を照射する発光素子と透過散乱した光を検出する受光素子とを少なくとも１組含むプローブにより、被検体の透過散乱光の強度を検出する光計測方法において、上記被検体に沿って上記プローブを走査して被検体の透過散乱光の強度を検出すると同時に、上記プローブの位置を検出することを特徴としている。
【０１３５】
それゆえ、被検体上に沿ってプローブを走査して各位置における光強度を測定した結果と、位置検出手段によるプローブの位置情報とを組み合わせることにより、測定結果を画像化することができるという効果を奏する。言い換えると、被検体の測定位置と、その位置における透過散乱光の強度との経時的な変化を連続的に重ねあわすことにより、画像化することができるという効果を奏する。
【０１３６】
さらに、プローブを走査して測定結果を画像化するので、発光素子および受光素子は、多数必要としない。したがって、１組の発光素子および受光素子からなる単チャンネル型プローブであっても、測定結果を画像化することができるという効果を奏する。また、その画像化された測定結果を見ながら、プローブを走査することもできるので、異常が確認された部分を長時間測定して経時的な変化も調べることができるという効果を奏する。
【図面の簡単な説明】
【図１】本発明の光計測装置の実施の一形態における画像計測用プローブ装置の構成を示したブロック図である。
【図２】近赤外領域における酸素化ヘモグロビン、脱酸素化ヘモグロビン、および水の吸収スペクトルを示したグラフである。
【図３】図１の受光素子および発光素子の発光および受光のタイミングチャートであり、図３（ａ）は発光素子１０ａの発光のタイミングチャート、図３（ｂ）は発光素子１０ｂの発光のタイミングチャート、図３（ｃ）は受光素子１２の受光のタイミングチャートである。
【図４】可動式プローブの構成を示した図である。
【図５】発光素子および受光素子の配置と、それによる点像応答関数を示した図であり、図５（ａ）は１組の発光素子および受光素子を用いた場合の図であり、図５（ｂ）は直交配置された２組の発光素子および受光素子を用いた場合の図である。
【図６】図５（ａ）の点像応答関数を変換した結果を示すグラフであり、図６（ａ）は、図５（ａ）の点像応答関数を変換する関数のグラフであり、図６（ｂ）は図６（ａ）の関数によって変換された結果を示すグラフである。
【図７】図５（ｂ）の点像応答関数を変換した結果を示すグラフであり、図７（ａ）は、図５（ｂ）の点像応答関数を変換する関数のグラフであり、図７（ｂ）は図６（ａ）の関数によって変換された結果を示すグラフである。
【図８】被検体の浅い位置にある光吸収物体のみを分離することのできる関数を示した図である。
【図９】本発明の実施の一形態にかかるプローブであって、ＰＣ用マウスを位置検出部とし、プローブと一体構造にした場合の斜視図である。
【図１０】図９とは異なる位置検出部と、プローブとが一体構造になった例を示す図であり、図１０（ａ）は単チャンネルのプローブの側面図であり、図１０（ｂ）は単チャンネルのプローブの底面図であり、図１０（ｃ）は２チャンネルプローブの側面図であり、図１０（ｄ）は２チャンネルプローブの底面図である。
【図１１】モンテカルロシュミレーションによる光子経路の履歴を示す図である。
【図１２】実施例２で使用した実験装置の構成を示した図である。
【図１３】発光素子から受光素子までの深さ方向への光子経路を示した図である。
【図１４】光吸収物体の深さと受光強度の関係を示したグラフである。
【図１５】発光素子から受光素子までの水平方向への光子経路を示した図である。
【図１６】実施例２の結果を示す図であり、図１６（ａ）は光吸収体が５ｍｍの深さにある場合の検出画像を示した図であり、図１６（ｂ）は、Ｙ＝３０の時の受光強度の変化を示した図である。
【図１７】実施例２の結果を示す図であり、図１７（ａ）は光吸収体が１０ｍｍの深さにある場合の検出画像を示した図であり、図１７（ｂ）は光吸収体が１５ｍｍの深さにある場合の検出画像を示した図である。
【図１８】実施例３で使用した実験装置の構成図である。
【図１９】実施例３の結果を示す図であり、プローブを走査した距離に対する受光強度の変化を示した図である。
【図２０】実施例４の結果を示す図であり、光学濃度の２次元分布を示した図である。
【図２１】実施例５の実験の様子を示した図である。
【図２２】実施例５の実験結果を示した図である。
【図２３】実施例６の結果を示す図であり、プローブを走査した距離に対する受光強度の変化を示した図である。
【図２４】実施例７の実験結果を示した図であり、図２４（ａ）および図２４（ｂ）は光吸収体が１０ｍｍの深さにある場合の２つの検出画像であり、図２４（ｃ）は図２４（ａ）と図２４（ｂ）とから計算された画像である。
【図２５】従来の単チャンネル型プローブの構成を示す図であり、図２５（ａ）はプローブの上面図であり、図２５（ｂ）は、プローブの側面図である。
【図２６】従来のマルチチャンネル型プローブの構成を示す図である。
【図２７】従来の光ファイバー型プローブの構成を示す図である。
【符号の説明】
１ 画像計測用プローブ装置（光計測装置）
２ 発光部
３ 受光部
４ 位置検出部（位置検出手段）
５ 制御部
６ 時計
７ 記憶部
８ データ処理部
９ 表示部（表示手段）
１０ 発光素子
１１ 発光制御部
１２ 受光素子
１３ 増幅器
１４ 被検体
１５ プローブ
１６ ｘ方向移動用レール
１７ ｙ方向移動用レール
１８ 外枠
１９ プローブ保持部（移動手段）
２０ 光散乱体
２１ 光吸収物体
２２ 光子（フォトン）
２３ 自動ステージ
５０ 発光素子
５１ 受光素子
５２ 被検体
５３ 光子経路領域
５４ 光ファイバ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical measurement device and an optical measurement method, and more particularly, to an optical measurement method using near-infrared spectroscopy that can easily display an image of, for example, muscle metabolism and cancer tissue. The present invention relates to an apparatus and an optical measurement method.
[0002]
[Prior art]
In recent years, the decline in physical function (eg, lifestyle-related diseases, lack of exercise, decreased basic physical fitness), increased medical expenses, and the problem of aging have led to more talks about physical well-being than physical well-being. Interest in quality of life (QOL), such as enriched life, is increasing.
[0003]
For this reason, a metabolism measuring device for the human body, which measures the image of a living body using near-infrared spectroscopy, has been developed and commercialized (for example, Patent Document 1, Non-Patent Documents 1 and 2). Such metabolism measuring devices can be classified into the following (1) to (3).
(1) Equipped with one set of light emitting element and light receiving element (single channel type)
(2) With multiple light emitting elements and light receiving elements (multi-channel type)
(3) With optical fiber (optical fiber type)
FIGS. 25A and 25B are a top view and a side view of a single-channel type probe using a pair of light emitting element 50 and light receiving element 51. FIG.
[0004]
As shown in FIG. 25, the single-channel probe has a light-emitting element 50 and a light-receiving element 51 in close contact with a subject 52 such as a living body, and irradiates the living body, which is the subject 52, with near-infrared light from the light-emitting element 50. Then, the transmitted / scattered light is detected by the light receiving element 51. The light receiving element 51 can detect the transmitted scattered light of the subject 52 within the range of the detectable region 53. By measuring the change over time of the light intensity detected by the light receiving element 51, for example, the consumption state of oxygen in the living body can be known.
[0005]
This single channel probe can detect the presence of a light absorbing object whose light intensity changes in the detectable region 53 between the light emitting element 50 and the light receiving element 51. However, it is no longer possible to specify the spatial position of the light absorbing object or measure the spatial distribution.
[0006]
By the way, the imaging of the detection result can extract useful information from the image by using the image processing ability of a person even when the signal contrast is low or the signal is buried in noise. . For example, being able to discriminate a lesion from a faint shadow on an X-ray photograph is a good example. Thus, imaging of the detection result is very useful for visually understanding the result.
[0007]
Therefore, in order to image the detection result, a multi-channel probe as shown in FIG. 26 has been developed. This probe has a large number of light emitting elements 50 and light receiving elements 51. In general, the light emitting element 50 and the light receiving element 51 sequentially illuminate the light emitting element 50 to irradiate the living body to avoid crosstalk, and the transmitted / scattered light is detected by the light receiving element 51. Further, by disposing a probe having a large number of light emitting elements 50 and light receiving elements 51 near the surface of a subject (for example, the surface of a living body), spatial information of light absorption can be obtained.
[0008]
In the multi-channel probe, it is necessary to change the measurement range and the arrangement of a large number of light emitting elements 50 and light receiving elements 51 according to the measurement site of the subject. However, in the conventional multi-channel probe, the light emitting element 50 and the light receiving element 51 are fixedly arranged. Therefore, the measurement range and the measurement interval cannot be changed according to the measurement site. That is, the degree of freedom of each element is low, and the elements cannot be freely arranged. Also, due to the physical size of each element, it is not possible to measure at intervals smaller than the element size.
[0009]
In order to improve such a low degree of freedom, a probe in which an optical fiber 54 is connected to a light emitting element 50 and a light receiving element 51 as shown in FIG. 27 has also been developed. Thereby, each element can be freely arranged, and information on a living body can be acquired at a high density. However, this optical measurement device requires a separate rigid installation instrument for installing the optical fiber 54 on the subject. For this reason, it cannot respond to the shape of the subject.
[0010]
[Patent Document 1] Japanese Patent Application Laid-Open No. 6-343625 (publication date: December 20, 1994)
[0011]
[Non-Patent Document 1] Yukihiro Ozaki and Seiichi Matsunaga, Clinical Chemistry, 24, 1995, p. 123-131.
[0012]
[Non-Patent Document 2] Motoki Oda et al., Laser Research, Vol. 25, No. 3, 1997, p. 204-207.
[0013]
[Problems to be solved by the invention]
As described above, the following problem occurs when spatial information of a subject is to be acquired by a conventional optical measurement device using infrared spectroscopy. That is,
{Circle around (1)} With a single-channel optical measurement device, spatial information cannot be obtained because measurement is performed at one location.
{Circle around (2)} In the multi-channel optical measurement device, the arrangement of elements and the measurement range cannot be changed according to the measurement site, and the degree of freedom is low. Further, the spatial resolution cannot be improved due to the physical size of the element. Further, the use of a large number of elements leads to an increase in cost.
{Circle over (3)} The optical fiber type optical measurement device cannot support the shape of the subject because a rigid installation tool for installing the device on the subject is required.
[0014]
As described above, the conventional optical measurement device has many problems, and it is difficult to introduce it at a clinical level, and it is far from being widely used in homes. Therefore, there is a strong demand for an optical measurement device that can image measurement results even with a small number of light emitting elements and light receiving elements and that can be practically used at home at low cost.
[0015]
Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an optical system that can be widely used in homes by imaging measurement results and simplifying the apparatus (ie, reducing the cost). An object of the present invention is to provide a measuring device and an optical measuring method.
[0016]
[Means for Solving the Problems]
The present inventors measure the metabolism and exercise intensity of muscles in human physical activity using the absorption properties of hemoglobin and myoglobin in the near infrared region, and visually present the results to measure their own body. We have been vigorously researching and developing an optical measurement device using near-infrared spectroscopy that allows us to know the activity status.
[0017]
As a result, in addition to a probe (optical sensor) including a light-emitting element and a light-receiving element, a position detection sensor that detects the position of the probe is provided, and the light detection of the subject is performed simultaneously while detecting the relative position over time. As a result, it has been found that spatial information of a subject can be reliably obtained even with a small number of elements, and the present invention has been completed.
[0018]
That is, the optical measurement device according to the present invention detects the intensity of the transmitted scattered light of the subject by using a probe including at least one set of a light emitting element that irradiates the subject with light and a light receiving element that detects the transmitted and scattered light. The optical measurement device is characterized by including a position detecting means for detecting the position of the probe.
[0019]
Conventionally, attempts have been made to image the metabolic distribution in a subject (human body). However, the conventional single-channel optical measurement device could not form an image because the light intensity was measured at one location. For this reason, the imaging method is a method of attaching a large number of light emitting elements and light receiving elements to a subject (human body). That is, the conventional imaging method uses a multi-channel optical measurement device.
[0020]
However, the multi-channel optical measuring device requires a large number of light emitting elements and light receiving elements, and thus the size of the apparatus is increased, so that the manufacturing cost increases; Has to be fixed, so that the measurement range cannot be changed and the arrangement of each element cannot be changed.
[0021]
On the other hand, according to the configuration described above, the position of the probe, that is, the position where the transmitted scattered light of the subject is measured, is detected by the position detecting means. Therefore, when the subject is irradiated with light from the light emitting element, the transmitted light scattered through the subject is detected by the light receiving element. At the same time, the position of the probe (ie, the measurement position of the subject) is also detected by the position detection means. As a result, by combining the result of measuring the light intensity at each position by scanning the probe along the subject and the position information of the probe by the position detecting means, the measurement result can be imaged. In other words, it is possible to form an image by continuously superimposing temporal changes in the measurement position of the subject and the intensity of the transmitted scattered light at that position.
[0022]
Furthermore, according to the above configuration, since the probe scans the measurement result and forms an image, a large number of light emitting elements and light receiving elements are not required. Therefore, the measurement result can be imaged even with a single-channel probe including a single light-emitting element and a light-receiving element. Therefore, the optical measurement device of the present invention does not require a large number of light emitting elements and light receiving elements, so that the apparatus is simplified. That is, since the cost of the apparatus can be reduced, an inexpensive optical measurement apparatus can be provided.
[0023]
In the optical measuring device according to the present invention, the probe and the position detecting means may have an integral structure.
[0024]
According to the above configuration, the probe and the position detecting means have an integral structure. Therefore, a small and lightweight optical measurement device can be provided. As a result, since the conventional apparatus is a large-sized apparatus, an apparatus which can be measured only in a laboratory or a large hospital can be provided in a home.
[0025]
The optical measurement device of the present invention may include a moving unit that moves the probe.
[0026]
According to the above configuration, the probe moves on the subject by the moving means. That is, the probe can automatically scan the subject by the moving means. The direction in which the moving means moves the probe is not particularly limited, and may be, for example, a two-dimensional direction, a three-dimensional direction, or a combination of these directions.
[0027]
In the optical measurement device of the present invention, the light emitting element may emit light in a near infrared region having two or more wavelengths having different center wavelengths.
[0028]
Here, the “light in the near-infrared region” refers to light in the near-infrared ray region, that is, the region from the vicinity of the long wavelength end (750 nm) of the visible light region to the vicinity of the long wavelength end (2500 nm) of the infrared region. It means light.
[0029]
Light in the near-infrared region is easily transmitted through a living body. For this reason, when the subject is a living body, the light emitted from the light emitting element to the subject is preferably near-infrared light. Further, non-invasive and non-destructive measurement is possible by using light in the near infrared region. Furthermore, the use of light in the near-infrared region facilitates the measurement operation and is suitable for routine analysis.
[0030]
Therefore, according to the above configuration, even if the subject is a living body, it is possible to provide an optical measurement device that is safe, easy, and low in restraint.
[0031]
Further, it is preferable that the light emitting element emits light in the near infrared region, which is light of two or more wavelengths having different center wavelengths. The reason for irradiating light of two or more wavelengths is that a change in absorbance due to a change in a target substance and a change in absorbance due to a change in density occur, and there are two unknown values.
[0032]
In the light in the near infrared region, it is preferable to irradiate light having a wavelength in the range of 700 nm to 900 nm. In the near-infrared region, when the wavelength is 700 nm or less, light scattering by a living body increases, and when the wavelength is 900 nm or more, absorption by water increases. Therefore, it becomes an obstacle when detecting the transmitted scattered light of the subject. Therefore, by setting the wavelength within the range of 700 nm to 900 nm, this interference can be prevented, and transmitted scattered light having a higher light intensity from the subject can be detected.
[0033]
In the present invention, the probe may include two or more sets of the light emitting element and the light receiving element arranged orthogonally.
[0034]
If the light-emitting element and the light-receiving element of the probe are arranged orthogonally, the detection value of the light-receiving element near the center, which is the intersection, becomes large. This is because outputs from orthogonal light receiving elements are overlapped. As a result, the output image of the detection result similarly has a particularly large output near the center. Therefore, by arranging the light emitting element and the light receiving element vertically, the ability to detect a light absorbing object can be improved. Therefore, the area of the light absorbing object can be narrowed down as compared with the case of a single light emitting element and a light receiving element, and only the light absorbing object close to the surface of the subject can be detected.
[0035]
In the present invention, the probe only needs to include one or more light emitting elements and one or more light receiving elements. That is, the probe only needs to include at least one set of the light emitting element and the light receiving element, and does not necessarily have to be paired. For example, light from a plurality of light emitting elements may be received by one light receiving element.
[0036]
Thus, the number of light emitting elements or light receiving elements can be reduced, and the size of the optical measurement device can be further reduced.
[0037]
Further, in order to solve the above-described problems, the optical measurement method according to the present invention provides a method for measuring an object by using a probe including at least one set of a light-emitting element for irradiating the object with light and a light-receiving element for detecting transmitted and scattered light. In the optical measurement method for detecting the intensity of the transmitted scattered light, the intensity of the transmitted scattered light of the object is detected by scanning the probe along the object, and the position of the probe is detected. I have.
[0038]
According to the above configuration, the detection of the transmitted scattered light of the subject by the probe and the position detection of the probe are simultaneously performed. As a result, by combining the result of measuring the light intensity at each position by scanning the probe along the subject and the position information of the probe by the position detecting means, the measurement result can be imaged. In other words, it is possible to form an image by continuously superimposing temporal changes in the measurement position of the subject and the intensity of the transmitted scattered light at that position.
[0039]
Furthermore, according to the above configuration, since the probe scans the measurement result and forms an image, a large number of light emitting elements and light receiving elements are not required. Therefore, the measurement result can be imaged even with a single-channel probe including a single light-emitting element and a light-receiving element. In addition, since the probe can be scanned while looking at the imaged measurement result, a portion where an abnormality is confirmed can be measured for a long time to check a change with time.
[0040]
As described above, according to the present invention, a subject such as a living body is irradiated with near-infrared light, and the near-infrared light is scattered and absorbed inside the living body, and the light transmitted through the living body is measured by the photodetector. Then, the light absorption distribution in the living body can be obtained. The greatest advantage of this method is that biological functions can be measured non-invasively. The principle of this method is based on the fact that near-infrared light absorption of blood exhibits wavelength dependence depending on the oxygenation state of the living body, and the oxygen metabolism function of the living body can be measured using this.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. Note that the present invention is not limited to this. In the following, a probe device for image measurement using near-infrared spectroscopy will be described as an example of the optical measurement device of the present invention.
[0042]
The image measurement probe device according to the present embodiment irradiates near-infrared light to the inside of a body, and changes in the intensity of light transmitted through the body to detect oxygenated hemoglobin (HbO) in blood. ₂ ) And deoxygenated hemoglobin (Hb) are detected to detect the metabolic state in the body. This probe can realize metabolism and cancer screening in brain, muscle and other organs.
[0043]
FIG. 1 is a block diagram showing the configuration of the simplest image measurement probe device 1 provided with a pair of light-emitting unit 2 and light-receiving unit 3 for near-infrared spectroscopy. First, the configuration of the image measurement probe device 1 will be described.
[0044]
The image measurement probe device (optical measurement device) 1 includes a light emitting unit 2, a light receiving unit 3, a position detection unit 4, a control unit 5, a clock 6, a storage unit 7, a data processing unit 8, and a display unit 9. I have.
[0045]
The light emitting unit 2 includes two light emitting elements 10a and 10b and a light emission control unit 11, and irradiates the subject with near-infrared light.
[0046]
As the light emitting element 10, for example, an element that is usually used as a light source such as a laser, a tungsten lamp, a halogen lamp, and a light emitting diode can be used. The light emitting element 10 irradiates a subject with light. The wavelength of light emitted from the light emitting element 10 is not particularly limited, but when detecting hemoglobin of a living body as in the present embodiment, a wavelength in a red to near-infrared region (that is, 630 nm to 1600 nm). It is preferable that At a wavelength of 700 nm or less, light scattering by a living body increases, and at a wavelength of 900 nm or more, absorption by water increases. Further, as shown in FIG. 2, due to the characteristic behavior of the absorption change between oxygenated hemoglobin and deoxygenated hemoglobin, the wavelength of the light emitting element 10 is such that the absorption by water is small and the light transmittance of the living body is high, That is, the thickness is preferably 700 nm to 900 nm.
[0047]
In the embodiment described later, two light emitting diodes (760 nm and 840 nm) having different center wavelengths are incorporated as the light emitting element 10. Thus, when light having different center wavelengths is irradiated, the change in absorbance due to the change (oxygen saturation) between oxygenated hemoglobin and deoxygenated hemoglobin, and the change in hemoglobin density (total blood volume) due to the change in blood volume. The change in absorbance due to the change can be measured separately.
[0048]
The light emission control unit 11 is an electronic circuit that controls driving of the light emitting element 10.
[0049]
The light receiving unit 3 includes a light receiving element 12 and an amplifier 13, and receives light transmitted and scattered by the subject.
[0050]
The light receiving element 12 is composed of, for example, a photodetector such as a silicon photodiode, and receives light transmitted and scattered by the subject.
[0051]
The amplifier 13 performs current voltage amplification of the photocurrent signal received by the light receiving element 12.
[0052]
FIG. 3 is an example of a timing chart of light emission and light reception in the light emitting unit 2 and the light receiving unit 3. As shown in FIG. 3, by alternately lighting the light emitting elements 10a and 10b, light from different light emitting elements 10a and 10b can be detected by one light receiving element. The timing of the light emission and light reception will be described in detail using examples. For example, as described below, when a PC mouse is used as the position detection unit 4 and the mouse is moved at 5 cm / s, 50 measurements per second are required to perform the absorbance measurement of the subject at 1 mm intervals. Need to repeat. When the two-wavelength light-emitting elements 10 are used, the light-emitting elements 10a and 10b may be turned on alternately at 50 Hz. Since light reception at this time is required twice, it is sufficient to receive light at 100 Hz. The time width of light reception is determined by the light receiving element 12, the amplifier 13, the A / D conversion circuit, and the sampling interval of the mouse (see FIG. 1). Actually, the time width of the light reception is determined by the response of the amplifier 13 at 1 kHz or the sampling interval of the mouse of 0.3 ms (average of 300 samplings at 100 kHz and 300 times, but slightly different depending on the type of mouse).
[0053]
The position detecting section 4 (position detecting means) detects a change in the position of the probe including the light emitting section 2 and the light receiving section 3. The position detection unit 4 includes, for example, a spherical position detection sensor and an optical position detection sensor for two-dimensional position measurement such as those used in a computer mouse, a three-dimensional position measurement magnetic sensor, an ultrasonic sensor, and an optical sensor. A sensor or the like can be used.
[0054]
In the case of a two-dimensional position measurement sensor, the plane is divided into small squares on a grid and discretized, and the discretized square area contains the center of the light-emitting unit 2 and the light-receiving unit 3 and is determined by the probe. Determine the position.
[0055]
In the case of the three-dimensional position detecting sensor, the space is divided by a small cubic region, and as in the case of the two-dimensional position measuring sensor, which cubic region contains the center of the light emitting unit 2 and the light receiving unit 3 Determines the position of the probe.
[0056]
The size of the square or cube is not particularly limited, and can be appropriately changed according to the measurement range, the measurement time, and the measurement accuracy. When an optical position detection sensor or an optical sensor is used, it is preferable to install a near-infrared light passing filter on the light receiving surface of the light receiving element 12 in order to prevent stray light from each sensor.
[0057]
Further, it is preferable that the position detecting section 4 has an integral structure with the probe. For example, FIG. 9 shows an example in which a position detection sensor for a PC mouse is applied to the position detection unit 4. The PC mouse includes a control unit 5, a light emitting element 10, a light emission control unit 11, a light receiving element 12, and an amplifier 13. Further, the position detection unit 4 (a position detection sensor of a normal PC mouse; not shown in FIG. 9) is provided between the light emitting element 10 and the light receiving element 12.
[0058]
Further, as shown in FIG. 10, the position detecting section 4 may be integrated with a single-channel or two-channel probe.
[0059]
As described above, by integrating the position detection unit 4 and the probe into an integral structure, the device can be downsized.
[0060]
The control unit 5 refers to the signal of the clock 6 to emit and receive light from the light emitting unit 2 and the light receiving unit 3, to detect the position of the probe by the position detecting unit 4, and to perform data processing by the data processing unit 8. Control the timing.
[0061]
The storage unit 7 stores a processing result of the data processing unit 8 described later.
[0062]
The data processing unit 8 refers to the control signal from the control unit and obtains the light intensity information from the light receiving unit 3, the position information from the position detection unit 4, and the information stored in the storage unit 7 at a certain point in time. The oxygen saturation at the position and the total blood volume are calculated. This data processing can be easily performed by a personal computer.
[0063]
Here, an example of data processing in the data processing unit 8 will be described. In general, when measuring living tissue, oxidized hemoglobin, deoxidized hemoglobin, and total blood volume (total hemoglobin) can be calculated from the amount of received light based on near-infrared spectroscopy. Then, by continuously plotting the calculated results, the measurement results can be imaged.
[0064]
The data processing unit 8 outputs the t-th (t is a natural number) measurement output S1 (t) (wavelength of the light emitting element 10a) of the light receiving unit 3 when the subject is irradiated with light having different center wavelengths from the light emitting elements 10a and 10b. OD is calculated from S2 (t) (measured output when irradiating the wavelength of light emitting element 10b) and S2 (t) (measured output when irradiating the wavelength of light emitting element 10b). At this time, the first measurement output is used as a reference. The calculation formula of the change in optical density △ OD for the light emitting elements 10a and 10b is shown by the following formulas (1) and (2).
[0065]
ΔOD1 = log [S1 (1) / S1 (t)] (1)
ΔOD2 = log [S2 (1) / S2 (t)] (2)
From the changes in the optical density for each of the light emitting elements 10a and 10b, three changes (density change of oxygenated hemoglobin △ A, density change of deoxygenated hemoglobin △ B, change of blood volume △ C) are shown in the following (3). It can be calculated from the formula.
[0066]
(Equation 1)

[0067]
Here, M is a 3 × 2 matrix, and the value of each element differs depending on the wavelength of the light emitting element used. Further, the storage unit 8 stores the measured amounts S1 (1) and S2 (1) at time 1 at each of the discrete points, and the average value of the measured amounts S1 (t) and S2 (t). The number of times the probe has passed that point is stored. For updating the stored value, an average of three new measured quantities is calculated from the newly acquired measured quantity, the average value of each measured quantity stored in the storage unit 8, and the number of passes. The three change amounts calculated from the change in the optical density calculated from the measured amount are output to the display unit 9 and displayed on the monitor of the display unit 9. As a display method, various conventionally known methods can be applied.
[0068]
Next, data processing using the image measurement probe device 1 of FIG. 1 will be described. The position of the probe 1 is detected by the position detector 4 of the probe 1. At the same time, the two light receiving elements 10a and 10b emit light alternately in response to a signal from the light emission control unit 11, and the light receiving unit 3 receives transmitted scattered light. The position detection information obtained by the position detection unit 4 and the near-infrared spectral information detected by the light receiving unit 3 are sent to a data processing unit 8 such as a computer in real time by a signal line, and are subjected to signal processing. The result of the signal processing by the data processing unit 8 is displayed on a display unit 9 such as a computer monitor.
[0069]
The probe 1 can be freely operated by a user's hand, and can scan any part of a subject (for example, a human body). Thus, the user can scan the subject while viewing the measurement image displayed on the display unit 9. In some cases, the probe 1 may be fixed, the intensity of the transmitted scattered light in a specific portion may be measured for a long time, and the temporal change in the light intensity in that portion may be observed.
[0070]
As described above, the optical measurement device according to the present invention irradiates a subject such as a living body with near-infrared light and measures transmitted / scattered light to acquire information on the subject in a non-invasive manner. can do. Further, information in the subject can be displayed as an image with a simple configuration.
[0071]
Although FIG. 1 includes two light emitting elements 10a and 10b, the number of light emitting elements 10 is not particularly limited. Also, the number of light receiving elements 12 is not particularly limited. That is, the number of elements constituting the probe is not particularly limited. In other words, the optical measurement device of the present invention may be a single-channel type or a multi-channel type.
[0072]
In the present invention, in order to more accurately scan on the subject, as shown in FIG. 4, the probe 15 may be attached to an auxiliary device to be movable. In FIG. 4, the outer frame 18 includes a pair of x-direction moving rails and 16, a y-direction moving rail 17 in a direction perpendicular thereto, and a probe holding unit 19. The probe 15 is fixed to the probe holding section 19. Thus, the probe 15 can scan in the two-dimensional directions of the x direction and the y direction. As a result, the precise position of the probe 15 detected from the two-axis (x-direction and y-direction) moving rails is detected. Therefore, spatially uniform measurements and long-term changes can be observed. Also, if a motor is attached to each of the moving rails 16 and 17 to automatically move the probe 15, spatial light measurement can be automated.
[0073]
In the above description, the image measurement device 1 including one set of the light emitting unit 2 and the light receiving unit 3 has been described, but a plurality of sets of the light emitting unit 2 and the light receiving unit 3 may be provided. If a plurality of sets are used, measurement can be performed at a plurality of locations, so that the measurement time is reduced and the resolution is improved. However, if a large number of pairs of the light emitting unit 2 and the light receiving unit 3 are provided, the number of elements increases, which leads to an increase in the size and cost of the device. Therefore, even when a plurality of sets of the light emitting unit 2 and the light receiving unit 3 are provided, it is better that the number is small.
[0074]
When a plurality of sets of the light emitting unit 2 and the light receiving unit 3 are provided, for example, as shown in FIG. 5, the light emitting element 10x and the light receiving element 12x and the light emitting element 10y and the light receiving element 12y are arranged orthogonally. Is preferred.
[0075]
FIG. 5A is a diagram illustrating a result of detecting a light absorbing object (not shown) by scanning the probe 15 with the light emitting element 10 including the light emitting elements of two wavelengths and the light receiving element 12. The horizontal axis represents the amount of movement of the probe 15 in the x direction when the center of the light emitting element 10 and the light receiving element 12 is located at the center of the light absorbing object, and the vertical axis represents the amount of movement in the y direction. The graph of FIG. 5A shows the center of the probe 15 when a minute light-absorbing object is measured by scanning the subject with a probe 15 having a set of a light emitting element 10x and a light receiving element 12x. An output image corresponding to a change in position, that is, a point image response function and its central profile are shown. The shading of the output image indicates a change in optical density due to the light absorbing object, and the higher the density, the greater the change in optical density. Here, the center of the graph is a case where the light absorbing object is located at the center between the light emitting element 10 and the light receiving element 12, and the optical density change becomes larger toward the center of the graph.
[0076]
On the other hand, FIG. 5B is a diagram showing a result of detecting a light absorbing object (not shown) by two sets of light emitting elements 10x and 10y and light receiving elements 12x and 12y arranged orthogonally. A comparison between the point image response function of FIG. 5B and the point image response function of FIG. 5A shows that the point image response function shown in FIG. 5B using two sets of light emitting elements 10x and 10y and light receiving elements 12x and 12y. However, the detected value near the center is larger than the spatial profile of FIG. This is because the outputs from the two light receiving elements 12x and 12y overlap. Similarly, the output image of FIG. 5B has a larger output especially near the center. In this manner, by vertically arranging the two light emitting elements 10x and 10y and the light receiving elements 12x and 12y, the ability to detect a light absorbing object can be improved.
[0077]
The point image response function as shown in FIGS. 5A and 5B may be converted by an arbitrary function. Thus, the ability to detect a light absorbing object can be further improved. The user can also change the signal processing curve that makes it easy to find the light absorbing object of the subject while adaptively changing the parameters of the function for the signal processing. Specifically, FIGS. 5A and 5B show changes in optical density detected when a minute light absorber is present at the center. The phrase “improving the ability to detect a light-absorbing object” means performing a process to reduce the area of the region represented by black in FIGS. 5A and 5B. The user combines the slope and center of the pixel value threshold processing with image processing that removes the outline of the image (that is, processing that changes the brightness, contrast, dynamic range, and sharpening processing of the image), The signal processing curve can be changed to make it easier to find the absorber. Since the optimal signal processing is expected to differ depending on the depth of the light absorber and the optical characteristics of the subject, the user can adjust the signal processing curve so as to obtain the most visible image while viewing the signal processing curve.
[0078]
For example, as shown in FIG. 6A, a change in the absorbance (optical density change) is output from the output image shown in FIG. ) May be converted. Thereby, as shown in FIG. 6B, the position of the light absorbing object can be further narrowed down spatially. That is, the ability to detect a light absorbing object can be improved. However, the size for narrowing the position of the light absorbing object in each direction is different.
[0079]
On the other hand, in the output image shown in FIG. 5B, as shown in FIG. 7A, the change in the absorbance detected by the light receiving element 12x and the change in the absorbance detected by the light receiving element 12y are particularly large. Absorbance change (optical density change) by a function that outputs a region (that is, a function that outputs only the region where the output images of the light receiving elements 12x and 12y overlap in the output image of FIG. 5B). May be converted. Thereby, as shown in FIG. 7B, the position of the light absorbing object can be narrowed down to a substantially circular shape. That is, the ability to detect a light-absorbing object can be further improved than in the case of FIG. Furthermore, since the shape of the narrowed-down area is substantially circular, the size of narrowing down the position of the light absorbing object in each direction is also substantially equal.
[0080]
Also, as shown in FIG. 8, the output image of FIG. 5B shows a case where the light absorbing object is close to immediately below the light emitting element 10x or 10y or the light receiving element 12x or 12y (that is, the light absorbing object is May be converted by a function which outputs only a large change in absorbance, which is seen in the case where the position is close to the surface of the image. If the light absorbing object is at a shallow position directly below the light emitting element 10x or 10y or the light receiving element 12x or 12y, a large change in absorbance will be detected. Therefore, by setting a large output only when this large change in absorbance is detected, it is possible to separate only a light absorbing object at a position shallow from the surface of the subject. Note that it was not possible to select and separate any function between one set of light emitting element and light receiving element.
[0081]
As described above, by vertically disposing the two light emitting elements 10x and 10y and the light receiving elements 12x and 12y, the area of the light absorbing object can be narrowed down more than in the case of one light emitting element 10x and the light receiving element 12y. Further, it is also possible to detect only a light absorbing object close to the surface of the subject.
[0082]
As described above, the optical measurement device of the present invention was obtained by irradiating a subject such as a living body with light having a different center wavelength in the near-infrared region and detecting transmitted light transmitted through the subject. By processing the signal, information inside the subject can be displayed as an image.
[0083]
More specifically, the probe is scanned along the surface of the human body, and the position detection unit obtains position detection information by adjusting the timing of light emission and light reception. Furthermore, a high-resolution image can be obtained by detecting the light intensity of each point and superimposing a large number of them.
[0084]
As described above, the optical measurement device of the present invention irradiates an object with light and detects the intensity of the transmitted scattered light, and the position detection sensor (position detection means) that detects the position of the probe. And have integrated.
[0085]
Further, according to the optical measurement device of the present embodiment, it is possible to measure a wide area with a small number of light emitting elements and light receiving elements. This allows the device to be miniaturized and can be attached to another instrument and used simultaneously. For example, by attaching the optical measurement device to another device such as an endoscope or a catheter, a therapeutic treatment can be performed while monitoring the metabolic state of the affected part.
[0086]
Furthermore, the optical measurement device of the present invention can easily store data of measurement results. As a result, if the measurement result is stored as image information, using image filing software makes it easier to browse the image information and save data. In addition, when performing an examination, a mark describing a date and a patient name is put on the skin in advance, and the acquisition result of the mark information is also stored at the same time, thereby avoiding the risk of confusing the measurement data with the patient.
[0087]
As shown in Table 1, the features of the multi-channel probe, the scanner probe, and the optical sensor probe are different. Since the optical measurement device of the present invention can be applied to any probe, the type of the probe may be changed according to the type of the subject or the purpose.
[0088]
[Table 1]

[0089]
The scanner-type probe has the following important features as compared with the multi-channel type probe.
(1) Spatial resolution improves
Since the scanner probe can scan from various directions, it is possible to narrow down the portion where the absorbance changes (that is, the position of the light absorbing object). On the other hand, in a multi-channel type (for example, solid sensor type) probe, since the light emitting element and the light receiving element are separated by about several centimeters, for example, when the transmitted scattered light of the subject changes (for example, deoxygenation). When the concentration of hemoglobin and oxygenated hemoglobin changes and the total blood volume changes), it can be seen that there is a portion between the light emitting element and the light receiving element. However, the location of the site cannot be specified any more. As described above, the scanner type probe has higher spatial resolution than the multi-channel type probe.
(2) Has depth sensitivity
In the case of the scanner type probe, the obtained image differs depending on the depth of the light absorbing object. Thereby, the depth of the light absorbing object can also be detected.
(3) Having spatial homogeneity of measurement results
Since the scanner-type probe of the present invention detects a light-absorbing object using a set of a light-emitting element and a light-receiving element, it is possible to prevent variations in measurement results due to differences between elements. That is, a highly accurate measurement result is obtained. On the other hand, in the multi-channel probe, since a light-absorbing object is detected by using a large number of light-emitting elements and light-receiving elements, measurement results vary depending on the difference between the elements. That is, the accuracy of the measurement result is lower than that of the scanner type probe.
(4) Can be searched according to measurement results
The user can measure the absorbance while watching the screen on which the measurement results appear in real time. Therefore, even if a site having a slight change in absorbance is observed, it is possible to determine whether the site is a lesion by scanning from various directions. If no apparent change in absorbance appears, another site can be quickly searched. Thereby, the measurement time can be reduced.
[0090]
The greatest features of the multi-channel type probe are that many sites can be measured at the same time, so that high-speed measurement is possible, and that the probe can be arranged according to the subject.
[0091]
(3) Features and advantages of the optical measurement device of the present invention
(1) Irradiating a subject such as a human body with light in the near-infrared region and measuring the biological functions noninvasively by the spectrum of transmitted and scattered light (the hemoglobin in the blood can be measured in an oxygenated-deoxygenated state. Utilizing that the absorbance shows wavelength dependence.)
[0092]
(2) It is possible to measure motor function and evaluate rehabilitation based on the metabolic state of muscles in physical activity. Further, since the number of elements constituting the device is small and the device can be manufactured at low cost, it is possible to measure shoulder stiffness at home, for example.
[0093]
(3) Can be applied to cancer (particularly breast cancer) screening and brain function measurement
The number of patients with breast cancer is increasing every year, and it is said that breast cancer will be the most common cancer among women in the near future. In cancer treatment, it is very effective to detect a tumor at an early stage. Recently, methods for detecting non-invasive early cancers using near-infrared light have been studied.
[0094]
This method utilizes the fact that the absorption spectrum of hemoglobin changes according to the binding state between hemoglobin and oxygen. That is, in the near-infrared region, since the absorption spectrum of hemoglobin changes depending on the state of oxygenation and deoxygenation, the change in hemoglobin concentration can be measured using near-infrared light. Then, from the obtained change in hemoglobin, the metabolic state of the living tissue can be examined non-invasively.
[0095]
Since tumor tissue is actively metabolized, there is a possibility that a breast tumor can be detected using a near-infrared spectral imaging system (the optical measurement device of the present invention). If a system capable of visualizing breast tumors can be realized for individuals (preferably at low cost), it will be effective for self-examination for early detection of breast cancer.
[0096]
Generally, early breast cancer is said to be up to 2 cm, but at this stage there are few subjective symptoms. To detect lumps by palpation, a size of 2.6 cm or more is required. Therefore, for early detection and early treatment of breast cancer, it is important to detect lumps of 2 cm or less.
[0097]
The optical measurement device of the present invention detects the intensity of light transmitted and scattered through a living body, thereby confirming the presence of a light absorbing substance (in this case, a lump). Therefore, even early breast cancer, which could not be detected by palpation as in the past, can be reliably detected. Therefore, it is useful for early detection and treatment of breast cancer.
[0098]
The present invention is not limited to the configuration of the above-described embodiment, and various changes can be made within the scope shown in the claims, and can be obtained by appropriately combining the technical means disclosed in the configurations of the different embodiments. Such embodiments are also included in the technical scope of the present invention.
[0099]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to this.
[0100]
In the following example, as shown in FIG. 12, an experiment was performed in which the light absorbing object 21 was put in a container containing the scatterer 20 and the probe 15 was scanned to obtain an image of the light absorbing object 21. .
[0101]
The probe 15 includes a light emitting diode (hereinafter, referred to as “LED”) having two wavelengths (760 nm and 840 nm) as a light emitting element, and a silicon photodiode with an amplifier (hereinafter, referred to as “PD”) as a light receiving element. An optical probe was used. When used as an actual device, the distance between the LED and the PD is designed to be 30 mm so that the change in absorption at a position deeper than the subcutaneous fat can be detected, and the depth from the surface of the scatterer to 15 mm. A light-absorbing object was installed at Examples 1 to 6 used one set of LED and PD, and Example 7 used two sets of LED and PD.
[0102]
[Example 1] (Photon path in scatterer)
In the present embodiment, an experiment was conducted for examining a photon (photon) path in a scatterer. Usually, the Monte Carlo method is often used to investigate the path of light propagation through a strong scatterer such as a living tissue. This Monte Carlo method tracks the trajectory of photons (photons) as shown in FIG. For example, the optical path length L between two points in the polar direction θ and the azimuth direction φ can be calculated by the following equation (4). Note that a broken line in FIG. 11 indicates a projected component on the xy plane.
[0103]
(Equation 2)

[0104]
Where R ₁ , R ₂ , R ₃ Is a pseudo-random number having a uniform appearance probability between 0 and 1, mt = ms + ma is the total amount of absorption count, and f (q) is a cumulative generating function of the scatterer's phase function p (q). .
[0105]
The energy absorbed in the ith interaction (Ei) is recursively expressed. The energy absorbed after the interaction is calculated using the weighting factor ma / mt, _{i + 1} = (Ma / mt) E _i Is represented by Typical values of the scattering coefficient ms, the absorption coefficient ma and the anisotropic coefficient g are 10.0 mm, respectively. ^-1 , 0.1mm ^-1 , 0.9.
[0106]
Based on this, the moving path of the photon was calculated by changing the distance between the LED and the PD. As a result, it was found that the photon paths were distributed to a depth approximately half the distance between the LED and the PD.
[0107]
FIG. 13 and FIG. 15 are diagrams showing photon paths obtained by performing a Monte Carlo simulation when the distance between the LED and the PD is 30 mm. FIG. 13 is a diagram illustrating a photon path in the depth direction (z direction) of the scatterer, and FIG. 15 is a diagram illustrating a photon path in the plane direction (y direction) of the scatterer. Here, the light receiving area of the PD was set to 10 mm × 10 mm, similarly to the PD used in Examples described later. As a result, the photon paths were distributed to a depth of 17 mm (z direction) from the surface.
[0108]
Further, the relationship between the depth direction (z direction) of the light absorbing object and the amount of transmitted scattered light of the subject by the PD was examined. FIG. 14 shows the result. The light absorbing object is a cube having a side of 5 mm, and is arranged at the midpoint between the LED and the PD. As shown in FIG. 14, when the light absorbing object was close to the surface of the subject, most of the photons that would have entered the PD were absorbed by the light absorbing object. On the other hand, when the absorber was deeper than 17 mm, most of the photons that would have entered the PD were incident on the PD without hitting the absorber.
[0109]
[Example 2] Experiment using a phantom
In this embodiment, milk: water = 1: 9 is used as the scatterer 20 in FIG. 12, and here, instead of scanning the probe, one rubber sphere (radius 3.0 mm) having a large light absorption rate is used as the light absorbing object 21. )It was used. A wire was attached to the rubber ball and moved by an automatic stage.
[0110]
Under these conditions, the rubber ball was adjusted to a depth of 5 mm, 10 mm, and 15 mm, and moved in the x and y directions by 60 mm around the light emitting element and the light receiving element, respectively. As a result, as shown in FIGS. 16 and 17, the rubber spheres at each depth could be imaged and detected. FIG. 16B is a diagram in which a change in received light intensity with respect to a moving distance in the x direction at y = 30 mm is recorded. As described above, according to the present embodiment, it has been clarified that an image of a light absorbing object can be formed by detecting a change in light intensity due to the light absorbing object in the scatterer.
[0111]
[Example 3] Experiment using a phantom (simulated biological material)
FIG. 18 shows the configuration of the experimental apparatus used in this example. A phantom was manufactured using an epoxy resin mixed with titanium oxide as a scatterer. The scanning of the probe was performed up to 60 mm in the x direction using a two-dimensional moving stage (hereinafter referred to as an XY stage) not shown. The positioning accuracy of the XY stage is 0.025 mm for each axis. The moving distance was recorded via the controller of the XY stage. In addition, the experiment which acquired the image of a rubber ball by scanning a probe 100 mm in x direction fixed the absorber at the depth of 5 mm, 10 mm, and 15 mm from the surface was performed.
[0112]
FIG. 19 is a diagram showing the result of the received light intensity at each position where the probe is scanned. As shown in FIG. 19, the interval between the three bottoms of the received light intensity matched the interval between the rubber balls. That is, it became clear that the change in the absorbance of the light absorber in the scatterer can be detected by the probe of this example.
[0113]
As described above, even when the phantom was formed as in this example, the light was received by the PD after being incident on the scatterer and scattered. The light receiving signal was amplified by an amplifier (amplifier) built in the light receiving unit. The amplified signal was stored in a PC (data processing unit) together with the position of the XY stage via an A / D conversion board.
[0114]
[Embodiment 4] Measurement in two-dimensional plane direction
The probe used in Example 3 was moved in a range of 100 mm × 10 mm on a phantom. The received light intensity at each position of the rubber ball was recorded. FIG. 20 is an image obtained by indicating the received light intensity by shading. Points where the received light intensity is low are shown dark. That is, the dark area corresponds to the position of the rubber ball. The received light intensity depends on the horizontal position and the depth of the absorber. Therefore, it became clear that an image representing a change in absorbance can be obtained by moving one channel.
[0115]
Example 5 Preliminary Experiment for Detecting Probe Position Using PC Mouse In order to detect the position of the probe (measurement position), it was examined whether the PC mouse could be applied. As shown in FIG. 21, the probe was attached to a PC mouse, and the position of the mouse cursor was converted to the actual position of the probe. Using this probe, the letter "M" in the alphabet was detected as a subject. As a result, as shown in FIG. 22, it was revealed that “M” of the subject can be detected using the probe attached to the mouse. That is, at the same time that the position of the probe is detected by the mouse, the absorbance of the subject can be measured.
[0116]
[Example 6]
The possibility of detecting the amount of movement of the probe using a PC mouse was examined by an experiment using a scatterer. The procedure was performed in the same manner as in Example 3 except that a probe attached to a PC mouse was used. As the probe moves over the phantom, the mouse cursor moves over PC coordinates. Based on the distance the probe moved, the distance the probe moved in the coordinates of the real space was converted to the distance the mouse cursor moved in the PC coordinates. FIG. 23 shows the received light intensity at each position. The plot obtained by the signal of the PC mouse is consistent with the curve obtained by the signal of the XY stage in Example 3. Thus, it became clear that the scanning probe using the mouse for PC can be applied to near-infrared spectral imaging.
[0117]
[Example 7] Experiment with a probe having two sets of light emitting and receiving parts arranged orthogonally An experiment was performed using two sets of LEDs and PD probes arranged orthogonally with the same experimental apparatus as in Example 2. went. The absorbing object was moved in a range of 50 mm × 50 mm at a depth of 10 mm. As a result, using the overlap of the outputs of the respective detectors shown in FIGS. 24 (a) and 24 (b), it is possible to further narrow the area where the absorbance changes as shown in FIG. 24 (c). It became. That is, the detection accuracy can be improved.
[0118]
【The invention's effect】
As described above, the optical measurement device according to the present invention uses the probe including at least one set of the light-emitting element that irradiates the subject with light and the light-receiving element that detects the transmitted and scattered light, to measure the intensity of the transmitted scattered light of the subject. In the optical measurement device for detecting the position of the probe, a position detecting means for detecting the position of the probe is provided.
[0119]
Therefore, by combining the result of measuring the light intensity at each position by scanning the probe along the subject and the position information of the probe by the position detecting means, the measurement result can be imaged. To play. In other words, it is possible to form an image by continuously superimposing a temporal change between the measurement position of the subject and the intensity of the transmitted scattered light at that position.
[0120]
Further, since the probe is scanned to image the measurement result, a large number of light emitting elements and light receiving elements are not required. Therefore, the measurement result can be imaged even with a single-channel probe including a single light-emitting element and a light-receiving element. Therefore, the optical measurement device of the present invention does not require a large number of light emitting elements and light receiving elements, so that the apparatus is simplified. That is, since the cost of the apparatus can be reduced, there is an effect that an inexpensive optical measurement apparatus can be provided.
[0121]
In the optical measuring device according to the present invention, the probe and the position detecting means may have an integral structure.
[0122]
Therefore, there is an effect that a compact and lightweight optical measurement device can be provided. Further, since the conventional apparatus is a large-sized apparatus, there is an effect that an apparatus which can be measured only at a research laboratory or a large hospital can be provided at home.
[0123]
The optical measurement device of the present invention may include a moving unit that moves the probe.
[0124]
Therefore, the probe can automatically scan the subject by the moving means.
[0125]
In the optical measurement device of the present invention, the light emitting element may emit light in a near infrared region having two or more wavelengths having different center wavelengths.
[0126]
Light in the near-infrared region is easily transmitted through a living body. For this reason, when the subject is a living body, the light emitted from the light emitting element to the subject is preferably near-infrared light. Further, non-invasive and non-destructive measurement is possible by using light in the near infrared region. Furthermore, the use of light in the near-infrared region facilitates the measurement operation and is suitable for routine analysis.
[0127]
Therefore, according to the above configuration, even if the subject is a living body, it is possible to provide an optical measuring device that is safe, easy, and low in restraint.
[0128]
Further, it is preferable that the light emitting element emits light in the near infrared region, which is light of two or more wavelengths having different center wavelengths. When measuring the intensity of the transmitted scattered light of the subject, there may be a substance that absorbs light from the light emitting element in addition to the substance to be measured. The presence of such a substance hinders the measurement and lowers the detection accuracy. Therefore, avoiding wavelengths that hinder measurement and irradiating light of two or more wavelengths has the effect of accurately measuring the light intensity of only the target substance.
[0129]
The light in the near infrared region is preferably irradiated with light having a wavelength in the range of 700 nm to 900 nm. At a wavelength of 700 nm or less, light scattering by living organisms increases, and at a wavelength of 900 nm or more, absorption by water increases. Therefore, it becomes an obstacle when detecting the transmitted scattered light of the subject. Therefore, by setting the wavelength within the range of 700 nm to 900 nm, there is an effect that the interference can be prevented and the transmitted scattered light of the subject can be accurately detected.
[0130]
Further, in the present invention, the probe may include two or more sets of the light emitting element and the light receiving element arranged orthogonally.
[0131]
Therefore, by arranging the light emitting element and the light receiving element vertically, there is an effect that the ability to detect a light absorbing object can be improved. In addition, it is possible to narrow the area of the light absorbing object as compared with the case of a single light emitting element and a light receiving element, and it is also possible to detect only the light absorbing object close to the surface of the subject.
[0132]
In the present invention, the probe only needs to include one or more light emitting elements and one or more light receiving elements.
[0133]
Therefore, the number of light emitting elements or light receiving elements can be reduced, and the size of the optical measurement device can be further reduced.
[0134]
In addition, as described above, the light measurement method according to the present invention uses the probe including at least one set of a light-emitting element that irradiates light to a subject and a light-receiving element that detects transmitted and scattered light, to transmit and scatter light of the subject. In the optical measurement method for detecting the intensity of light, the probe is scanned along the object to detect the intensity of the transmitted scattered light of the object, and at the same time, the position of the probe is detected.
[0135]
Therefore, by combining the result of measuring the light intensity at each position by scanning the probe along the subject and the position information of the probe by the position detecting means, the measurement result can be imaged. To play. In other words, it is possible to form an image by continuously superimposing a temporal change between the measurement position of the subject and the intensity of the transmitted scattered light at that position.
[0136]
Further, since the probe is scanned to image the measurement result, a large number of light emitting elements and light receiving elements are not required. Therefore, even with a single-channel type probe including a single light-emitting element and a light-receiving element, the measurement result can be imaged. In addition, since the probe can be scanned while viewing the imaged measurement result, there is an effect that a portion where an abnormality is confirmed can be measured for a long time and a change with time can be examined.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image measurement probe device according to an embodiment of an optical measurement device of the present invention.
FIG. 2 is a graph showing absorption spectra of oxygenated hemoglobin, deoxygenated hemoglobin, and water in the near infrared region.
3A and 3B are timing charts of light emission and light reception of the light receiving element and the light emitting element of FIG. 1. FIG. 3A is a timing chart of light emission of the light emitting element 10a, and FIG. 3B is a light emission timing of the light emitting element 10b. FIG. 3C is a timing chart of the light reception of the light receiving element 12.
FIG. 4 is a diagram showing a configuration of a movable probe.
FIG. 5 is a diagram showing an arrangement of light emitting elements and light receiving elements and a point image response function based on the arrangement, and FIG. 5 (a) is a diagram when one set of light emitting elements and light receiving elements is used; FIG. 5B is a diagram when two sets of light emitting elements and light receiving elements arranged orthogonally are used.
FIG. 6 is a graph showing a result of converting the point image response function of FIG. 5 (a), and FIG. 6 (a) is a graph of a function converting the point image response function of FIG. 5 (a); FIG. 6B is a graph showing a result converted by the function of FIG.
FIG. 7 is a graph showing a result of converting the point image response function of FIG. 5 (b), and FIG. 7 (a) is a graph of a function of converting the point image response function of FIG. 5 (b); FIG. 7B is a graph showing a result converted by the function of FIG.
FIG. 8 is a diagram showing a function capable of separating only a light absorbing object at a shallow position of a subject.
FIG. 9 is a perspective view of the probe according to the embodiment of the present invention, in which a PC mouse is used as a position detection unit and is integrated with the probe.
FIG. 10 is a diagram showing an example in which a position detecting unit and a probe different from those in FIG. 9 are integrated, and FIG. 10A is a side view of a single-channel probe, and FIG. FIG. 10C is a bottom view of the single-channel probe, FIG. 10C is a side view of the two-channel probe, and FIG. 10D is a bottom view of the two-channel probe.
FIG. 11 is a diagram showing a history of photon paths by Monte Carlo simulation.
FIG. 12 is a diagram showing a configuration of an experimental apparatus used in Example 2.
FIG. 13 is a diagram showing a photon path in a depth direction from a light emitting element to a light receiving element.
FIG. 14 is a graph showing the relationship between the depth of a light absorbing object and the received light intensity.
FIG. 15 is a diagram showing a photon path in a horizontal direction from a light emitting element to a light receiving element.
FIG. 16 is a diagram showing the results of Example 2, FIG. 16 (a) is a diagram showing a detected image when the light absorber is at a depth of 5 mm, and FIG. FIG. 9 is a diagram showing a change in received light intensity when = 30.
17A and 17B are diagrams showing the results of Example 2; FIG. 17A is a diagram showing a detection image when the light absorber is at a depth of 10 mm; FIG. It is the figure which showed the detection image at the time of a body being 15 mm in depth.
FIG. 18 is a configuration diagram of an experimental apparatus used in Example 3.
FIG. 19 is a diagram illustrating a result of the third embodiment, and is a diagram illustrating a change in received light intensity with respect to a scanning distance of a probe.
FIG. 20 is a diagram showing a result of Example 4, and showing a two-dimensional distribution of optical density.
FIG. 21 is a diagram showing a state of an experiment in Example 5.
FIG. 22 is a diagram showing experimental results of Example 5.
FIG. 23 is a diagram illustrating a result of Example 6, and illustrating a change in received light intensity with respect to a distance scanned by a probe.
24A and 24B are diagrams showing experimental results of Example 7, and FIGS. 24A and 24B are two detection images when the light absorber is at a depth of 10 mm. (C) is an image calculated from FIGS. 24 (a) and 24 (b).
25A and 25B are diagrams showing a configuration of a conventional single channel type probe, FIG. 25A is a top view of the probe, and FIG. 25B is a side view of the probe.
FIG. 26 is a diagram showing a configuration of a conventional multi-channel probe.
FIG. 27 is a diagram showing a configuration of a conventional optical fiber probe.
[Explanation of symbols]
1 Image measurement probe device (optical measurement device)
2 Light emitting unit
3 Receiver
4 Position detection unit (position detection means)
5 control part
6 clock
7 Storage unit
8 Data processing unit
9 Display part (display means)
10 Light-emitting element
11 Light emission control unit
12 light receiving element
13 Amplifier
14 Subject
15 Probe
16 x direction rail
17 Rail for y-direction movement
18 Outer frame
19 Probe holder (moving means)
20 light scatterers
21 Light absorbing objects
22 Photons
23 Automatic Stage
50 light emitting element
51 Light receiving element
52 subject
53 photon path region
54 Optical Fiber

Claims (8)

A probe including at least one set of a light-emitting element that irradiates the subject with light and a light-receiving element that detects transmitted and scattered light, a light measurement device that detects the intensity of transmitted and scattered light of the subject,
An optical measuring device comprising a position detecting means for detecting the position of the probe. The optical measurement device according to claim 1, wherein the probe and the position detection unit have an integral structure. The optical measurement device according to claim 1, further comprising a moving unit configured to move the probe. 4. The optical measurement device according to claim 1, wherein the light-emitting element emits light in a near-infrared region of two or more wavelengths having different center wavelengths. 5. The optical measurement device according to any one of claims 1 to 4, wherein the light emitting element emits light having a wavelength within a range of 700 nm to 900 nm. The optical measuring device according to any one of claims 1 to 5, wherein the probe includes two or more sets of the light emitting element and the light receiving element arranged orthogonally. The optical measurement device according to claim 1, wherein the probe includes one or more light emitting elements and one or more light receiving elements.
The light emitting element and the light receiving element do not have to form a pair. An optical measurement method for detecting the intensity of transmitted scattered light of an object by a probe including at least one set of a light emitting element that irradiates the object with light and a light receiving element that detects transmitted and scattered light,
An optical measurement method, wherein the probe is scanned along the subject to detect the intensity of the transmitted scattered light of the subject and, at the same time, the position of the probe is detected.

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