JP3631215B2 - Radiation image processing apparatus, radiation image processing system, radiation imaging system, radiation imaging apparatus, radiation image processing method, computer-readable storage medium, and program - Google Patents

Description

【００４１】
同様に、グリッドの有無及びグリッド種類によってグリッド消去処理のパラメータが制御される。グリッド消去処理は固定グリッドシステムの場合にのみ行われ、移動グリッドシステムの場合は行われない。固定グリッドシステムによる撮影の利点は、高速の撮影が可能となることであるが、反面、グリッドによる縞目が画像中に顕在して、医師によっては診断の妨げになるとして嫌われる。そこで、画像中に存在するグリッドによる縞目を画像処理により消し去る消去処理が行われる。
【００４２】
センサ系のサンプリング周波数Ｆｓ（ナイキスト周波数Ｆｎ＝Ｆｓ／２）が決まれば、どのグリッドを使用した場合に、どの周波数に縞目が発生するかは計算により求めることができる。グリッドの周波数をＦｇとすると、Ｆｎ＞Ｆｇであれば、Ｆｇの周波数に縞目ができるので、フィルタ処理によりこれを取り除く。このときのバンドカットフィルタの周波数は、検知されたグリッドの種類に基づいて、画像処理パラメータ記憶部４４内に保存されている画像処理パラメータテーブルを参照することにより、例えばカット周波数Ｆａとして決定される。
【００４３】
また、Ｆｎ＜Ｆｇであれば、Ｆｎ−（Ｆｇ−Ｆｎ）＝２Ｆｎ−Ｆｇに、グリッドに起因した縞目が発生することになる。この場合も同様に、この２Ｆｎ−Ｆｇの周波数が、検知されたグリッドの種類に基づいて、画像処理パラメータ記憶部４４内に保存されている画像処理パラメータテーブルを参照することにより得られ、当該周波数に応じたバンドカットフィルタが構成される。尚、このバンドカットフィルタ自体が画像処理パラメータ記憶部４４内に保存されていてもよい。
【００４４】
ＱＡ処理の１つである周波数処理も、グリッドの有無及び種類によりパラメータが調整される。ここでは、グリッド消去処理において副作用として弱められた周波数領域が復元されることと、完全に消去されていないグリッドを強調することなく、診断に有効なその他の周波数帯域を強調することが目的である。これらのフィルタパラメータも検知手段からのグリッド情報を基に、画像処理パラメータテーブルを検索して決定される。
【００４５】
最後に階調処理を行うが、一般的にグリッドを使用しない撮影では、若干ではあるが、散乱線により画像全体のコントラストが低下する。これを補正するために、階調処理ではコントラストを上げて変換することが望ましい。
【００４６】
表１のテーブルに示した処理に関して、グリッドの有無及び種類によりパラメータが変更される過程を開示したが、グリッドに関連する処理はこれに限定されることはなく、その他にも例えば、診断画像の後処理に関する画像圧縮においても、グリッドを強調しないようにパラメータが調整されることが考えられる。また、グリッド情報を利用した処理パラメータの調整法は、上述のものに限定されるものではなく、通常医師や撮影技師の希望により決定される。
【００４７】
以上に説明したグリッドの有無情報またはグリッドの種別情報に基づいて画像処理を行う場合の画像処理フローを、図７および図８を用いて説明する。図７は、グリッド判別回路３１がグリッドの有無のみを検知する場合の、当該検知結果に基づく画像処理部１８による画像処理フローを説明している。まず、画像処理部１８はグリッド判別回路３１によって判別されたグリッドの有無情報を受け取る（ステップＳ７０１）。次に、画像処理部１８はグリッドの有無情報に基づいて、ゲイン画像テーブルからゲイン画像を選択する（ステップＳ７０２）。尚、固定グリッドシステムを用いる場合には、上述のようにグリッドの有無に拘らずゲイン画像テーブルから読み出されるゲイン画像は同一である。すなわち、グリッドを使用せずに予め取得されたゲイン画像を選択する。移動グリッドシステムを用いる場合には、上述のようにグリッドの有無によって線質（Ｘ線のエネルギー）が異なるため、グリッドの有無に応じて異なるゲイン画像を選択する。つづいて、画像処理部１８はグリッドの有無情報に基づいて、他の画像処理パラメータを選択する（ステップＳ７０３）。画像処理パラメータとしては例えば、前記表１のようなグリッド消去処理、周波数強調処理、階調処理等がある。例えば、少なくともグリッドの有無情報に基づいて、グリッド消去処理を行うか否かが選択される。また、グリッド消去処理の有無に応じて、鮮鋭化処理などの周波数強調処理パラメータが選択される場合もある。また、少なくともグリッドの有無情報に基づいて、階調処理のパラメータ（例えば、ガンマ）が選択される。画像処理部１８は以上のようにして選択されたパラメータに基づいて画像処理を実行する（ステップＳ７０４）。
【００４８】
図８は、グリッド判別回路３１がグリッドの有無情報のみならずグリッドの種別情報も検知する場合の、当該検知結果に基づく画像処理部１８による画像処理フローを説明している。まず、画像処理部１８はグリッド判別回路３１によって判別されたグリッドの有無および種別情報を受け取る（ステップＳ８０１）。次に、画像処理部１８はグリッドの有無および種別情報に基づいて、ゲイン画像テーブルからゲイン画像を選択する（ステップＳ８０２）。尚、固定グリッドシステムを用いる場合には、上述のようにグリッドの有無に拘らずゲイン画像テーブルから読み出されるゲイン画像は同一である。すなわち、グリッドを使用せずに予め取得されたゲイン画像を選択する。移動グリッドシステムを用いる場合には、上述のようにグリッドの有無及び種別によって線質（Ｘ線のエネルギー）が異なるため、グリッドの有無及び種別に応じて異なるゲイン画像を選択する。つづいて、画像処理部１８はグリッドの有無および種別情報に基づいて、他の画像処理パラメータを選択する（ステップＳ８０３）。画像処理パラメータとしては例えば、前記表１のようなグリッド消去処理、周波数強調処理、階調処理等がある。例えば、少なくともグリッドの有無情報に基づいて、グリッド消去処理を行うか否かが選択される。また、少なくともグリッドの種別情報に基づいて、グリッド消去処理の他のパラメータ（例えば、前述のバンドカットフィルタの周波数特性等）が選択される。また、グリッド消去処理の有無および他のパラメータに応じて、鮮鋭化処理などの周波数強調処理パラメータが選択される場合もある。さらに、グリッドの種別に応じて散乱線量などが変化し、その結果微小構造のコントラストが変化することがあり、このような場合、少なくともグリッドの有無および種別情報に基づいて周波数強調処理パラメータが選択される。また、少なくともグリッドの有無および種別情報に基づいて、階調処理のパラメータ（例えば、ガンマ）が選択される。画像処理部１８は以上のようにして選択されたパラメータに基づいて画像処理を実行する（ステップＳ８０４）。
【００４９】
以上の説明では、グリッドの有無或いは種類に関する情報により画像処理パラメータを調整することについて述べたが、そもそも撮影法によりグリッドを替えるということは、撮影法により適切なグリッドが決まるということである。本実施形態の撮影装置においては、Ｘ線曝射による撮影前に、どのような部位をどのような意図で撮影するかを示す撮影法の入力が、表示装置６に付随する入力部、或いはネットワークインタフェース４６を経由して病院情報システムＨＩＳや放射線情報システムＲＩＳから行われる。
【００５０】
例えば、表２に示すように、胸部の正面であればグリッドＡの使用が適切であり、四肢画像であればグリッドを使用しないのが適切である場合を想定する。
【００５１】
【表２】

【００５２】
本実施形態では、表２を用いて撮影法から検索される適切なグリッドの種類とグリッド検知手段において検知されたグリッドの種類との比較を行い、選択されたグリッドが適切でなければ、表示装置６にその旨を表示する機能を持たせることができる。なお、表２に示した撮影法とグリッドとの対応テーブルは予め設定され、適応グリッドテーブル記憶部４５に保存されている。
【００５３】
上述の説明では、グリッドの特性を検知する手段を有することを前提にしており、図３はグリッドユニット１５の構成と、撮影装置内のグリッドの有無及び撮影装置内にどのような特性のグリッドが装着されているかを判別する方法を示している。しかし、グリッドの有無の検出手段のみを有する構成として機構を簡略化することもできる。
【００５４】
この場合は、どのような特性のグリッドが装着されているかの判定は別の手段を用いて行う。例えば、グリッド有無検出手段により検知されたグリッドの有無状態の遷移をモニタしておき、グリッドのない状態の存在の有無でグリッドが変更されたか否かを検知する構成とし、入れ換えがあった場合には、表示部６にグリッド種類判別のための空曝射の要求パネルが表示される。
【００５５】
この空曝射は、被写体がない状態での撮影を意味し、しかもグリッドを固定した撮影を意味する。この固定グリッド空曝射画像を画像処理部１８とは別に設けた図示しない画像解析部で解析することにより、グリッドの種別の判定が行われる。画像解析手法にはフーリエ変換を使用した周波数解析が使用でき、具体的にはスペクトルの位置でグリッドの周波数、スペクトルの大きさでグリッドの格子比を判定することが可能である。このような画像解析手法を使用してグリッド種別判定が行われた後には、先の説明と同様に、当該判定結果が画像処理パラメータの選択に使用される。
【００５６】
図９に実施の形態の基本的構成を示す。本実施の形態は、サンプリング周波数（画素密度、解像度、画素サイズ又は画素ピッチ等ともいう）の異なる複数の放射線像検出器（以下、イメージセンサとも称す）が同一の画像処理部に接続されて構成される画像処理システムの例である。この場合、各放射線像検出器の解像度に依存して画像処理のパラメータを変更する必要がある。
【００５７】
図９において、第１イメージセンサ９０および第２イメージセンサ９２は各々グリッドが着脱可能に構成され、また各々第１グリッド判別部９１および第２グリッド判別部９３が設けられている。尚、各グリッド判別部は、グリッドが装着されているか否かの判別をするものであってもよいし、グリッドの有無のみならず、グリッドの周波数、格子比などの違いに基づくグリッドの種別を判別するものであってもよい。グリッドの種別まで判別する場合には、上述の実施の形態で説明したように、複数種類のグリッドを使用し、使用されるグリッドの種別に応じた画像処理パラメータを選択することが可能になる。
【００５８】
画像処理部９６は所定の手段によって、各イメージセンサに固有の解像度に関する情報を取得する。このため、各イメージセンサは当該情報を外部装置（画像処理部９６）に示すための指示部、例えば当該情報を送信するための送信部を有して構成されることが望ましい。例えば、当該情報が各イメージセンサから画像処理部９６に、第１のデータインタフェース９４、第２のデータインタフェース９５を介して、画像情報とともに、画像情報の転送に先立って、あるいは他のタイミングで転送されるようにすればよい。
【００５９】
あるいは、画像処理部９６が同様又は他の手段により各イメージセンサの識別情報（ＩＤ情報）を認識できるようにするとともに、当該識別情報に対応させて各イメージセンサの解像度情報をイメージセンサ情報テーブルとして記憶するイメージセンサ情報テーブル記憶部９７を画像処理部９６が参照可能に構成してもよい。典型的には、コンピュータ内外のコンピュータ可読メモリに当該テーブルを記憶させて、各イメージセンサの特性情報を管理すればよい。
【００６０】
また、上述の実施の形態におけるグリッドユニット１５およびグリッド判別回路３１を用いたシステムと同様の仕組みで、画像処理部９６が各イメージセンサの解像度情報を取得できるように構成されていてもよい。尚、本実施の形態では、簡単のため、データインタフェース９４および９５のいずれを介して画像データが取得されたかに応じて、画像データを取得したイメージセンサが識別されるものとする。画像処理部９６は、識別されたイメージセンサの解像度情報をイメージセンサ情報テーブルから得、得られた解像度情報に応じて画像処理パラメータを決定し、決定された画像処理パラメータに基づいて画像処理を実行する。
【００６１】
図１０のフローチャートを用いて、図９の画像処理システムによって実行される処理の流れを説明する。まず、イメージセンサ１およびイメージセンサ２のいずれかのイメージセンサを使用して画像データの取得が行われる（ステップＳ１００１）。
【００６２】
画像処理部９６は、第１のデータインタフェース９４および第２のデータインタフェース９５のいずれを通して画像データが取得されたかに依存して、画像データを取得したイメージセンサを識別し、識別されたイメージセンサの解像度を、イメージセンサ情報テーブルを参照することによって取得する（ステップＳ１００２）。尚、解像度情報は前述のイメージセンサ情報テーブルに含まれている。
【００６３】
次に、画像処理部９６は画像データを取得したイメージセンサについてのグリッドの有無および／または種別情報を、上述の実施の形態と同様の手法により取得する（ステップＳ１００３）。本情報の取得のタイミングは、本例に限定されず画像処理を実行する前であればよく、例えば、画像処理直前であってもよいし、画像データ取得直前であってもよい。
【００６４】
次いで、画像処理部９６はグリッドの有無および／または種別情報に応じて、上述の実施の形態と同様の思想の下に、ゲイン画像テーブルからゲイン画像を選択する（ステップＳ１００４）。但し、本実施の形態におけるゲイン画像の選択にあたっては、グリッドの有無および／または種別情報に加えて、画像データを取得したイメージセンサの識別情報も使用される。また、イメージセンサがその解像度（画素密度）を可変できるものである場合には、当該解像度情報もゲイン画像の選択にあたって使用される。
【００６５】
次に、画像処理部９６は画像処理パラメータテーブルから画像処理パラメータを選択する（ステップＳ１００５）。この選択も上述の実施の形態と同様の思想の下に行われるが、本実施の形態ではグリッドの有無および／または種別情報に加えて、イメージセンサの解像度情報をも使用して画像処理パラメータを選択することが上述の実施の形態と異なる。尚、画像処理パラメータテーブルには予め作成されたデフォルトのパラメータが記憶されており、このテーブルから、グリッドの有無および／または種別情報、およびイメージセンサの解像度情報に応じた画像処理パラメータが選択される。尚、このテーブルに記憶される画像処理パラメータはデフォルトのパラメータであって、画像処理の際、個別の状況（被写体特性等）に依存してユーザがパラメータを変更することも可能である。
【００６６】
イメージセンサの解像度に応じて画像処理パラメータを調整する必要性について、例を挙げて説明する。例えば、７ｘ７画素のマスクサイズのフィルタを用いて空間周波数処理（例えば、ＱＡ処理中で行われる画像鮮鋭化処理等）を行う場合、適用される画像データのピクセルサイズ（画素密度）が異なれば、前記７ｘ７画素のフィルタの空間周波数特性も異なるものになる。ところが、臨床的な画像を想定した場合、例えば、人体における所定部位の血管のエッジを形成する空間周波数は概ね一定であるため、画像処理の目的が血管を見えやすくする（強調する）ことであれば、空間フィルタの周波数特性はイメージセンサの解像度（画素密度）とは関係なく概ね一定にすることが望ましい。
【００６７】
よって、解像度の異なる画像に対して概ね等しい周波数特性を持ったフィルタ処理を行うためには、イメージセンサの解像度（画素密度）に応じた係数および／またはマスクサイズを有するフィルタを使用する必要がある。よって、本実施の形態では、グリッドの有無および／または種別情報、並びにイメージセンサの解像度情報に応じて画像処理パラメータが選択される。
【００６８】
また、グリッド消去処理においても、イメージセンサの解像度に依存したパラメータの調整が必要となる。例えば、イメージセンサのナイキスト周波数をＦｎ、グリッドの周波数をＦｇとしたとき、Ｆｇ≦Ｆｎであれば空間周波数Ｆｇ、Ｆｇ＞Ｆｎであれば空間周波数２Ｆｎ−Ｆｇのストライプ状パターン（グリッドに起因した縞目）が画像上に現れる。従って、グリッド消去処理を行う場合、画像処理部９６はグリッドの有無および／または種別情報、並びにイメージセンサの解像度情報に基づいて、グリッド起因縞の周波数（Ｆｇまたは２Ｆｎ−Ｆｇ）を演算または選択する。
【００６９】
尚、イメージセンサの特性に依存して、使用に適したグリッドの周波数が存在する場合がある。各イメージセンサに対し好適なグリッド周波数は理論的または実験的に決められる。筆者らの実験によれば、１６０ミクロン画素ピッチのイメージセンサに対しては約４０ｌｐ／ｃｍ、１００ミクロン画素ピッチのセンサであれば約６０ｌｐ／ｃｍのグリッドが好適である（ここで、ｌｐはｌｉｎｅ ｐａｉｒの意）。この場合、各イメージセンサで取得された画像において、各グリッドは異なる周波数スペクトルを形成する。グリッド消去処理では、この周波数スペクトルに対応した周波数成分を除去する空間フィルタが使用される。よって、この場合も、画像処理部９６はグリッドの有無および／または種別情報、並びにイメージセンサの解像度情報に基づいて、グリッド消去処理のパラメータを演算または選択する。尚、ここで、使用したイメージセンサにグリッドが装着されていなかった（グリッド判別回路３１によりグリッド「なし」と判別された）場合には、グリッド消去処理のパラメータは「なし」であり、すなわちグリッド消去処理が実行されないことになる。
【００７０】
また、上述の実施の形態と同様に、画像処理部９６はグリッドの有無および／または種別情報、並びにイメージセンサの解像度情報に基づいて、階調処理のパラメータ（例えば、ガンマ）や画像圧縮のパラメータ等を選択する。
【００７１】
尚、グリッドの有無および／または種別情報、並びにイメージセンサの解像度情報に応じて調整される処理パラメータおよびその調整手法は、上述のものに限定されるものでなく、むしろ種々の変更が可能であるとともに、通常医師や撮影技師の希望に基づいて決定される。
【００７２】
画像処理部９６は以上のようにして決定（演算又は選択）されたパラメータに基づいて画像処理を実行する（ステップＳ１００６）。
【００７３】
（他の実施形態）
本発明を、複数の装置（例えば、１以上の画像処理装置、１以上のインターフェース、１以上の放射線撮影装置、及び１以上のＸ線発生装置、等）から構成されるシステム、又は画像処理装置及び放射線撮影装置を統合した構成等のいずれにも適用可能であることは言うまでもない。
【００７４】
また、本発明の目的は、上述の実施の形態の機能を実現するためのソフトウェアのプログラムコードを記憶した記憶媒体を、システム或いは装置に供給し、そのシステム或いは装置のコンピュータ（ＣＰＵ又はＭＰＵ等）が記憶媒体に格納されたプログラムコードを読み出して実行することによっても、達成されることは言うまでもない。
【００７５】
この場合、記憶媒体から読み出されたプログラムコード自体が上述の実施の形態の機能を実現することとなり、当該プログラムコード、及び当該プログラムコードを記憶した記憶媒体は本発明を構成することとなる。
【００７６】
プログラムコードを供給するための記憶媒体としては、ＲＯＭ、フロッピーディスク、ハードディスク、光ディスク、光磁気ディスク、ＣＤ−ＲＯＭ、ＣＤ−Ｒ、磁気テープ、不揮発性のメモリカード等を用いることができる。
【００７７】
また、コンピュータが読み出したプログラムコードを実行することにより、上述の実施の形態の機能が実現されるだけでなく、そのプログラムコードの指示に基づき、コンピュータ上で稼動しているＯＳ等が実際の処理の一部又は全部を行い、その処理によって上述の実施の形態の機能が実現される場合も本発明を構成することは言うまでもない。
【００７８】
さらに、記憶媒体から読み出されたプログラムコードが、コンピュータに挿入された拡張機能ボードやコンピュータに接続された機能拡張ユニット等に備わるメモリに書き込まれた後、そのプログラムコードの指示に基づき、その機能拡張ボードや機能拡張ユニット等に備わるＣＰＵなどが実際の処理の一部又は全部を行い、その処理によって上述の実施の形態の機能が実現される場合も本発明を構成することは言うまでもない。
【００７９】
本発明が上述のプログラムコード及びコンピュータ可読記憶媒体に適用される場合において、当該プログラムコードは、例えば、上述の実施の形態において記述された図１０で示されるフローチャートに対応するプログラムコードであり、また当該記憶媒体は、例えば、当該フローチャートに対応するプログラムコードを格納する。
【００８０】
図１１は、上述のコンピュータの機能１１００の構成の一例を示したものである。
【００８１】
コンピュータ機能１１００は、上記図１１に示すように、ＣＰＵ１１０１と、ＲＯＭ１１０２と、ＲＡＭ１１０３と、キーボード（ＫＢ）１１０９に対するキーボードコントローラ（ＫＢＣ）１１０５と、表示部としてのＣＲＴディスプレイ（ＣＲＴ）１１１０に対するＣＲＴコントローラ（ＣＲＴＣ）１１０６と、ハードディスク（ＨＤ）１１１１及びフロッピーディスク（ＦＤ）１１１２に対するディスクコントローラ（ＤＫＣ）１１０７と、任意のネットワーク１１２０に接続されたネットワークインターフェースカード（ＮＩＣ）１１０８とが、システムバス１１０４を介して互いに通信可能に接続されて構成されている。
【００８２】
ＣＰＵ１１０１は、ＲＯＭ１１０２若しくはＨＤ１１１１に記憶されたソフトウェア（プログラムコード等）、又はＦＤ１１１２より供給されるソフトウェアを実行することで、システムバス１１０４に接続された各構成部を総括的に制御する。
【００８３】
すなわち、ＣＰＵ１１０１は、所定の処理シーケンスに従った処理プログラムを、ＲＯＭ１１０２若しくはＨＤ１１１１、又はＦＤ１１１２から読み出して実行することで、上述の実施の形態における動作を実施するための制御を行う。
【００８４】
ＲＡＭ１１０３は、ＣＰＵ１１０１の主メモリ或いはワークエリア等として機能する。
【００８５】
ＫＢＣ１１０５は、ＫＢ１１０９や図示していないポインティングデバイス等からの指示入力等を制御する。
【００８６】
ＣＲＴＣ１１０６は、ＣＲＴ１１１０等の表示装置による表示を制御する。
【００８７】
ＤＫＣ１１０７は、ブートプログラム、種々のアプリケーションソフトウェア、編集ファイル、ユーザファイル、ネットワーク管理プログラム、及び上述の実施の形態に係る処理プログラム等を記憶するＨＤ１１１１又はＦＤ１１１２等へのアクセスを制御する。
【００８８】
ＮＩＣ１１０８は、ネットワーク１１２０上の装置或いはシステム等と双方向にデータをやりとりする。
【００８９】
尚、本発明は上述の実施の形態に限られず、むしろ種々の変更及び改変が本発明の精神及び範囲の内において可能である。そこで、本発明の範囲を公衆に通告するため、前述の特許請求の範囲が作成されている。
【００９０】
【発明の効果】
以上説明したように本発明によれば、画素密度の異なる複数のイメージセンサを選択的に使用可能とし、かつ該画素密度及びグリッドに関する情報に応じた画像処理を行うための放射線画像処理装置、放射線画像処理システム、放射線撮影システム、放射線撮影装置、放射線画像処理方法、コンピュータ可読記憶媒体、及びプログラムを提供することができる。
【図面の簡単な説明】
【図１】放射線撮影装置の構成図
【図２】放射線撮影部の平面図
【図３】グリッドユニットの正面図
【図４】図３のＡ−Ａ線に沿った断面図
【図５】経過時間に対するモータに流れる電流値を示したグラフ図
【図６】画像処理部のブロック構成図
【図７】画像処理部による画像処理フローを説明するための図
【図８】画像処理部による画像処理フローを説明するための図
【図９】システム構成を説明するための図
【図１０】図９のシステムによる処理フローを説明するための図
【図１１】実施の形態の機能または動作に係るプログラムを実行可能なコンピュータの構成を示すブロック図
【符号の説明】
９４ 第１のデータインタフェース
９５ 第２のデータインタフェース
９６ 画像処理部
９７ イメージセンサ情報テーブル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiographic image processing apparatus, a radiographic image processing system, a radiographic imaging system, a radiographic imaging apparatus, a radiographic image processing method, a computer-readable storage medium, and a radiographic image processing apparatus for processing a radiographic image captured by selectively using a grid. And programs.
[0002]
[Prior art]
When a certain type of phosphor is irradiated with radiation such as X-rays, α-rays, β-rays, γ-rays, electron beams, and ultraviolet rays, a part of the radiation energy is accumulated in the phosphors. It is known that when this phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated emission according to the accumulated energy. Called a phosphor or stimulable phosphor.
[0003]
Conventionally, using this stimulable phosphor, radiation image information of a subject such as a human body is once recorded on the sheet of the stimulable phosphor, and this stimulable phosphor sheet is scanned using excitation light such as laser light. Thus, stimulated emission light is emitted, and the obtained stimulated emission light is photoelectrically read to obtain an image signal. A radiographic image information recording / reproducing system that outputs a radiographic image of a subject as a visible image on a display device such as a recording material such as a photographic photosensitive material or a CRT based on the image signal is disclosed in, for example, Japanese Patent Application Laid-Open No. 55-12429, This is proposed in Japanese Patent No. 56-11395. Such a method is called computed radiography (CR).
[0004]
In recent years, a system for taking a radiographic image of a subject using a semiconductor image sensor having a large area has been developed. This system has a practical advantage that an image can be recorded over a very wide range of radiation exposure compared to a conventional radiographic system using silver salt photography. That is, X-rays with a very wide dynamic range are read as electrical signals using photoelectric conversion means, and the electrical signals are further converted into digital signals. By processing this digital signal and outputting the radiation image as a visible image to a recording material such as a photographic photosensitive material or a display device such as a CRT, a good radiation image can be obtained even if the radiation exposure varies to some extent. It is done.
[0005]
In the CR system using the above-described stimulable phosphor, various types of grids are used in order to reduce scattered radiation from a subject or the like. However, in an imaging system using a semiconductor image sensor, a stripe is included in a captured image due to the relationship between the sampling frequency of the image sensor (the reciprocal of the pixel pitch) and the grid frequency (the reciprocal of the pitch of a radiation-absorbing member such as lead). Pattern (also referred to as moire fringes) occurs. Therefore, in a photographing system using a semiconductor image sensor, information related to the grid to be used is detected and detected so that a plurality of grids having different frequencies can be used and moire fringes are removed by image processing. Japanese Patent Application Laid-Open No. 2000-083951 by the present applicant discloses that photographing or image processing is executed in accordance with the information.
[0006]
[Problems to be solved by the invention]
However, in the above Japanese Patent Laid-Open No. 2000-083951, it is very effective in a system including one image sensor, but a plurality of image sensors having different sampling frequencies (pixel density) can be selectively connected and used. The system was not considered.
[0007]
Therefore, the present invention enables a plurality of image sensors having different pixel densities to be selectively used, and a radiographic image processing apparatus, a radiographic image processing system, and radiography for performing image processing according to information on the pixel density and grid It is an object to provide a system, a radiographic apparatus, a radiographic image processing method, a computer-readable storage medium, and a program.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the first invention provides: Radiation image transmitted through the grid for removing scattered radiation In a radiographic image processing apparatus for processing radiographic image data from a radiographer that detects
In the radiograph Attached Scattered ray removal grid Type of Grid information acquisition means for acquiring information about,
In the radiograph Image sensor Pixel density information acquisition means for acquiring information on the pixel density of
Calculate or select the frequency of grid-derived fringes based on the grid type and the pixel density, and perform grid erasure processing based on the frequency And image processing means for executing the above.
[0009]
In a second aspect based on the first aspect, the image processing means comprises: Change processing parameters according to the grid type and the pixel density It is configured to execute at least one of gain correction processing, frequency processing, gradation processing, and image compression processing.
[0010]
According to a third invention, in the first invention, The grid elimination process is a band cut filter process having a frequency characteristic determined by the calculation or the selected frequency. It is characterized by that.
[0011]
A fourth invention is a radiographic image processing system in which a plurality of apparatuses are communicably connected to each other, and each element constituting the radiographic image processing apparatus of any one of the first to third inventions is provided. It is characterized by having.
[0012]
A fifth invention is a radiation imaging system comprising the radiation image processing device according to any one of the first to third inventions and the radiation imaging device.
[0013]
6th invention is a radiography apparatus which has a radiography apparatus which detects a radiographic image, The grid information presentation means which presents the information regarding the scattered radiation removal grid in the said radiography apparatus to an external apparatus, In the said radiography apparatus It has pixel density information presentation means for presenting information related to the pixel density of the radiation image detector to an external device.
[0014]
The seventh invention Radiation image transmitted through the grid for removing scattered radiation In a radiographic image processing method for processing radiographic image data from a radiographer that detects
In the radiograph Attached Scattered ray removal grid Type of Grid information acquisition process to acquire information about,
In the radiograph Image sensor A pixel density information acquisition step of acquiring information on the pixel density of
Calculate or select the frequency of grid-derived fringes based on the grid type and the pixel density, and perform grid erasure processing based on the frequency And an image processing step for executing the above.
[0015]
An eighth invention is the radiographic image processing apparatus of the first to third inventions, the radiographic image processing system of the fourth invention, the radiographic system of the fifth invention, and the radiographic apparatus of the sixth invention. A computer-readable storage medium storing a program for causing a computer to realize the function of the apparatus or system of any one of the inventions.
[0016]
A ninth invention is a computer-readable storage medium storing a program for causing a computer to execute the operation of the radiographic image processing method of the seventh invention.
[0017]
A tenth aspect of the invention is the radiographic image processing apparatus of the first to third aspects of the invention, the radiographic image processing system of the fourth aspect of the invention, the radiographic system of the fifth aspect of the invention, and the radiographic apparatus of the sixth aspect of the invention. It is a program for causing a computer to realize the function of the apparatus or system of any one of the inventions.
[0018]
An eleventh invention is a program for causing a computer to perform the operation of the radiographic image processing method of the seventh invention.
[0019]
Other features and advantages of the present invention will become apparent from the following description made with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar components throughout the drawings.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings (FIGS. 1 to 11).
[0021]
FIG. 1 is a configuration diagram of an X-ray digital image capturing apparatus (radiation imaging apparatus), and FIG. 2 is a plan view of a radiation imaging section (radiation imaging apparatus) constituting the X-ray digital image capturing apparatus. The X-ray digital image capturing apparatus includes an X-ray generation unit 1, a gantry 2, a radiation imaging unit (radiography unit) 3, a control unit 4 that controls the radiation imaging unit 3, and a cable that connects the radiation imaging unit 3 and the control unit 4. 5 and a monitor 6 for displaying a signal processed in the control unit 4.
[0022]
The radiographic unit 3 can be moved up and down via the movable unit 2a of the gantry 2, and the vertical movement can freely change the height according to the position of the subject. The subject located between the generator 1 can be photographed at a predetermined position.
[0023]
In the housing 11 of the radiation imaging unit 3, a grid including a radiation image receiving unit 14 including a radiation image detector 12 and a reading circuit 13 that reads a signal from the radiation image detector 12, and a grid that removes scattered rays from the subject. A unit 15 is incorporated. Further, a handle 15 a is provided on a side surface of the grid unit 15. Further, an openable / closable cover 16 is attached to the side surface of the radiation imaging unit 3 via a hinge 17.
[0024]
The grid unit 15 and the radiation image receiving unit 14 are arranged in parallel in the casing 11 of the radiation imaging unit 3, and the cover 16 is opened and the handle 15 a is pulled to take out the grid unit 15 to the outside of the radiation imaging unit 3. Is possible.
[0025]
The control unit 4 supplies power to the image processing unit 18, the radiation image receiving unit 14, the image processing unit 18, and the like which perform filtering processing such as noise reduction and edge enhancement of the image digital signal supplied from the reading circuit 13. It is composed of The connection between the radiation imaging unit 3 and the control unit 4 is connected by a cable 5 including a signal line and a power line, and this cable 5 is covered and protected by a flexible tube 20. Since the flexible tube 20 is made of a flexible material, it can follow the vertical movement of the radiation imaging unit 3.
[0026]
In the X-ray imaging apparatus system having such a configuration, the radiation imaging unit 3 is moved to an imaging target region of a patient, and X-rays are emitted from the X-ray generation unit 1 to perform imaging. Then, the image information of the subject imaged by the radiation imaging unit 3 is transmitted as a digital signal to the image processing unit 18 through the cable 5, and various image processing is performed depending on whether or not the grid is used and the type of grid.
[0027]
3 is a front view of the grid unit 15, and FIG. 4 is a cross-sectional view taken along the line AA in FIG. The grid unit 15 includes a handle 15 a, a grid body 15 b, and a grid holding unit 21, and the grid body 15 b mounted in the radiation imaging unit 3 is fixed to the frame-shaped grid holding unit 21 via a fixing member 22. The grid holding portion 21 is bent at four sides at right angles in order to improve the strength. Convex protrusions 23, 24, and 25 are formed at equal intervals on the end of the side surface of the bent four sides facing the handle 15a. Further, a switch mounting plate 26 is provided in the radiation imaging section 3, and microswitches 27, 28, 29 are provided on the switch mounting plate 26 so as to face the protrusions 23, 24, 25, and each microswitch. A grid discriminating circuit 31 is connected to 27, 28, and 29 via a lead wire 30.
[0028]
When the grid unit 15 is mounted on the radiation imaging unit 3, the micro switch 27 is arranged so as to be turned on from the off state by the protrusion 23 provided on the grid holding unit 21. Similarly, the microswitches 28 and 29 are changed from the off state to the on state by the protrusions 24 and 25, respectively. The on / off state of each microswitch 27, 28, 29 is transmitted to the grid discriminating circuit 31 via the lead wire 30, and the presence / absence of the grid main body 15b and the type of the grid main body 15b are determined.
[0029]
For example, if all the microswitches 27, 28, and 29 are in the on state, it is identified that the grid body 15b having the first characteristic A is attached, and if only the microswitch 27 is in the on state, the second characteristic B has the second characteristic B. It may be set to identify that the grid body 15b is mounted, and to identify that the grid body 15b itself is not mounted if all of the micro switches 23, 24, and 25 are in the off state.
[0030]
Such setting is not limited to this example, and various settings can be made by combining the on / off states of the microswitches 27, 28, and 29. The detection means is not limited to the microswitches 27, 28, and 29, and may be a reed switch using magnetic force or a photoswitch using light, and the number of detection means can be selected as necessary.
[0031]
Furthermore, although the case where the stationary grid main body 15b is used has been described in the above-described embodiment, such a detection method is not limited to the stationary grid main body 15b, but the grid main body 15b is attached to the radiation image receiving unit 14 during imaging. The present invention can also be applied to a photographing apparatus that moves and photographs. For example, a driving unit such as a motor for moving the grid body 15b is separately provided in the radiation imaging unit 3, and the grid body 15b is configured to be movable with respect to the grid holding unit 21, and only the grid body 15b is driven by the driving unit during imaging. It can be moved at a predetermined speed.
[0032]
In this case, the detection means provided in the grid holding unit 21 can be used as it is as in the above-described embodiment, and the presence or absence of the grid or the characteristics of the grid body 15b can be identified regardless of the movement of the grid body 15b. it can.
[0033]
By providing such a detection means in the common grid holding part 21 without providing it directly in the grid main body 15b, the following advantages can be mentioned. That is, regardless of the grid thickness depending on the grid ratio, the grid insertion part in the photographing apparatus can be simplified to the same shape. Further, in the case of shooting for moving the grid, since the microswitch is not repeatedly turned on and off every time the grid is moved, durability is improved. In addition, the grid can be protected when the grid is detached from the photographing apparatus. Further, if the presence of the grid body 15b in the radiation imaging unit 3 is detected and the grid driving means is operated only in the case of imaging for moving the grid, the grid body 15b is mounted in the radiation imaging unit 3. It is possible to prevent the grid driving means from being erroneously driven when the image is not taken or when the grid is fixed.
[0034]
Also, parameters that vary depending on the load applied to the motor during photographing or when the grid driving means, for example, only the motor is operated before photographing without using the above-described grid detecting micro switches 27, 28, 29. If the amount is detected to identify the presence or weight of the grid body 15b, there is no need to provide a new grid detection means. Specifically, for example, the current value flowing through the motor when the motor is operated is used as a parameter amount, and the current value when the current value is in an equilibrium state is compared with a preset discrimination current value. The characteristics of the grid body 15b depending on the presence or absence of the grid body 15b and the weight of the grid body 15b can be identified. As the characteristic of the grid body 15b depending on the weight of the grid body 15b, the amount of lead in the grid body 15b, that is, the grid density can be considered.
[0035]
FIG. 5 is a graph showing the value of the current flowing through the motor with respect to the elapsed time. When the grid main body 15b does not exist in the radiation imaging unit 3, the load torque applied to the motor is very small, so the current value from the start of rotation of the motor changes as shown by curve C, and the current balance value is the current balance value. It converges to Ic after the arrival time t1. Similarly, the current values when the grids A and B are mounted are curves a and b, respectively, and the current values are Ia and Ib after the current equilibrium arrival times t2 and t3, respectively. Since the grid B has a higher grid density and higher weight than the grid A, the load torque also increases, and the current value satisfies Ib>Ia> Ic. In addition, the rate of increase of the current value at the start of rotation of the motor is large in the order of curves b, a, and c, and the current equilibrium arrival time is also in the order of t3>t2> t1.
Here, if the discrimination current values Ica and Iab are set in advance so that Ib>Iab>Ia>Ica> Ic, if the current value i after the current equilibrium arrival time t3 is Ica> i, the grid is If it is not attached, and Iab>i> Ica, i> Iab, it can be seen that the attached grids are A and B, respectively, and it is possible to identify the presence / absence of the grid and the type. In the present embodiment, the parameter amount that fluctuates depending on the load applied to the grid driving means is the current value i in the equilibrium state, but it may be the rate of increase of the current value or the required time until the equilibrium state is reached. The same effect can be obtained even if the number of rotations of the motor inversely proportional to the torque is used.
[0036]
FIG. 6 shows a block circuit configuration diagram of the image processing unit 18. The image processing unit 18 uses the information on the presence / absence and type of the grid main body 15b obtained by the method described above to perform appropriate image processing. You can choose. The image processing unit 18 includes a preprocessing unit 41, a QA processing unit 42, an image storage unit 43, an image processing parameter storage unit 44, an adaptive grid table storage unit 45, and a network interface 46. In the preprocessing unit 41, gain correction, offset processing, LOG conversion, and grid erasure processing (not shown) are performed.
[0037]
In shooting in a fixed grid system, all gain images are shot without using a grid. That is, in the fixed grid system, the gain image W1 photographed without using the grid is used regardless of the presence / absence of the grid and the type. Moreover, in the imaging | photography in a moving grid system, the gain images W2-W4 collected with the grid used for imaging | photography are used. One reason for this is that, since the energy characteristics of transmitted X-rays differ depending on the grid, it is preferable to use a gain image obtained with X-rays having similar radiation quality.
[0038]
Even in the case of the moving grid system, when the grid is not mounted, the gain image obtained without using the grid is used for correction. However, shading does not occur even if the gain image is not switched by the grid, and the image quality is not greatly affected even if the gain image is not switched.
[0039]
Such gain images W1 to W4 are stored in the image storage unit 43, and the images shown in Table 1 are stored in the image processing parameter storage unit 44 from the result of the grid detection unit under the control of the preprocessing unit 41. The processing parameter table is referred to, and the corresponding gain image is downloaded from the image storage unit 43.
[0040]
[Table 1]

[0041]
Similarly, the parameters of the grid erasure process are controlled by the presence / absence of the grid and the grid type. The grid erasure process is performed only for the fixed grid system, not the moving grid system. The advantage of imaging with a fixed grid system is that high-speed imaging is possible, but on the other hand, grid-like stripes appear in the image and are disliked by doctors as an obstacle to diagnosis. Therefore, an erasing process is performed to erase the fringes due to the grids present in the image by image processing.
[0042]
If the sampling frequency Fs of the sensor system (Nyquist frequency Fn = Fs / 2) is determined, it is possible to obtain by calculation which fringe is generated at which frequency when which grid is used. Assuming that the frequency of the grid is Fg, if Fn> Fg, stripes are formed in the frequency of Fg, and this is removed by filtering. The frequency of the band cut filter at this time is determined as, for example, the cut frequency Fa by referring to the image processing parameter table stored in the image processing parameter storage unit 44 based on the type of the detected grid. .
[0043]
Further, if Fn <Fg, stripes due to the grid are generated in Fn− (Fg−Fn) = 2Fn−Fg. Similarly in this case, the frequency of 2Fn-Fg is obtained by referring to the image processing parameter table stored in the image processing parameter storage unit 44 based on the detected grid type, and the frequency A band cut filter according to the above is configured. The band cut filter itself may be stored in the image processing parameter storage unit 44.
[0044]
In frequency processing, which is one of QA processing, parameters are adjusted depending on the presence and type of a grid. The purpose here is to restore the frequency domain that was weakened as a side effect in the grid erasure process and to emphasize other frequency bands that are useful for diagnosis without emphasizing the grid that has not been completely erased. . These filter parameters are also determined by searching the image processing parameter table based on the grid information from the detection means.
[0045]
Finally, although gradation processing is performed, in general, when shooting without using a grid, the contrast of the entire image is reduced due to scattered rays, although it is slightly. In order to correct this, it is desirable to perform conversion by increasing the contrast in the gradation processing.
[0046]
Regarding the processing shown in the table of Table 1, the process of changing the parameters depending on the presence and type of the grid has been disclosed, but the processing related to the grid is not limited to this. In image compression related to post-processing, it is conceivable that parameters are adjusted so as not to emphasize the grid. Further, the method for adjusting the processing parameters using the grid information is not limited to the above-described method, and is usually determined according to the wishes of a doctor or a radiographer.
[0047]
An image processing flow when image processing is performed based on the grid presence / absence information or grid type information described above will be described with reference to FIGS. FIG. 7 illustrates an image processing flow by the image processing unit 18 based on the detection result when the grid determination circuit 31 detects only the presence / absence of a grid. First, the image processing unit 18 receives grid presence / absence information determined by the grid determination circuit 31 (step S701). Next, the image processor 18 selects a gain image from the gain image table based on the grid presence / absence information (step S702). When a fixed grid system is used, the gain image read from the gain image table is the same regardless of the presence or absence of the grid as described above. That is, a gain image acquired in advance without using a grid is selected. When the moving grid system is used, the gain image (X-ray energy) varies depending on the presence or absence of the grid as described above, and therefore a different gain image is selected depending on the presence or absence of the grid. Subsequently, the image processing unit 18 selects another image processing parameter based on the grid presence / absence information (step S703). Examples of the image processing parameters include grid elimination processing, frequency enhancement processing, gradation processing, and the like as shown in Table 1 above. For example, whether or not to perform grid erasure processing is selected based on at least grid presence / absence information. Further, frequency enhancement processing parameters such as sharpening processing may be selected depending on whether or not grid erasing processing is performed. Further, a gradation processing parameter (for example, gamma) is selected based on at least grid presence / absence information. The image processing unit 18 performs image processing based on the parameters selected as described above (step S704).
[0048]
FIG. 8 illustrates an image processing flow by the image processing unit 18 based on the detection result when the grid determination circuit 31 detects not only the presence / absence information of the grid but also the type information of the grid. First, the image processing unit 18 receives the presence / absence and type information of the grid determined by the grid determination circuit 31 (step S801). Next, the image processing unit 18 selects a gain image from the gain image table based on the presence / absence of the grid and the type information (step S802). When a fixed grid system is used, the gain image read from the gain image table is the same regardless of the presence or absence of the grid as described above. That is, a gain image acquired in advance without using a grid is selected. When the moving grid system is used, since the quality of the radiation (X-ray energy) varies depending on the presence and type of the grid as described above, different gain images are selected depending on the presence and type of the grid. Subsequently, the image processing unit 18 selects another image processing parameter based on the presence / absence of the grid and the type information (step S803). Examples of the image processing parameters include grid elimination processing, frequency enhancement processing, gradation processing, and the like as shown in Table 1 above. For example, whether or not to perform grid erasure processing is selected based on at least grid presence / absence information. Also, other parameters (for example, frequency characteristics of the above-described band cut filter) are selected based on at least the grid type information. Further, frequency enhancement processing parameters such as sharpening processing may be selected depending on the presence / absence of grid erasing processing and other parameters. Furthermore, the scattered dose etc. may change depending on the type of grid, and as a result the contrast of the microstructure may change.In such a case, the frequency enhancement processing parameter is selected based on at least the presence / absence of the grid and type information. The A gradation processing parameter (for example, gamma) is selected based on at least the presence / absence of the grid and the type information. The image processing unit 18 performs image processing based on the parameters selected as described above (step S804).
[0049]
In the above description, adjustment of the image processing parameter is described based on information on the presence or type of the grid. However, changing the grid by the imaging method originally means that an appropriate grid is determined by the imaging method. In the imaging apparatus according to the present embodiment, an input of an imaging method that indicates what part is to be captured with what intention before imaging by X-ray exposure is an input unit or network associated with the display device 6. This is performed from the hospital information system HIS and the radiation information system RIS via the interface 46.
[0050]
For example, as shown in Table 2, it is assumed that it is appropriate to use the grid A if it is the front of the chest, and it is appropriate not to use the grid if it is a limb image.
[0051]
[Table 2]

[0052]
In the present embodiment, the appropriate grid type searched from the imaging method using Table 2 is compared with the grid type detected by the grid detection means, and if the selected grid is not appropriate, the display device 6 can have a function of displaying the fact. Note that the correspondence table between the imaging method and the grid shown in Table 2 is set in advance and stored in the adaptive grid table storage unit 45.
[0053]
In the above description, it is assumed that there is a means for detecting the characteristics of the grid. FIG. 3 shows the configuration of the grid unit 15, the presence / absence of the grid in the imaging apparatus, and what kind of grid is in the imaging apparatus. It shows a method of determining whether it is attached. However, the mechanism can be simplified as a configuration having only a detection means for the presence or absence of a grid.
[0054]
In this case, the determination of what kind of grid is mounted is performed using another means. For example, the transition of the presence / absence state of the grid detected by the grid presence / absence detection means is monitored, and it is configured to detect whether the grid has been changed based on the presence / absence of a state without a grid. The display unit 6 displays an air exposure request panel for determining the grid type.
[0055]
This sky exposure means shooting in the absence of a subject, and shooting with a fixed grid. The fixed grid sky exposure image is analyzed by an image analysis unit (not shown) provided separately from the image processing unit 18 to determine the type of grid. As the image analysis method, frequency analysis using Fourier transform can be used. Specifically, it is possible to determine the grid frequency at the spectrum position and the grid ratio of the grid by the spectrum size. After the grid type determination is performed using such an image analysis method, the determination result is used to select an image processing parameter, as described above.
[0056]
FIG. 9 shows a basic configuration of the embodiment. In the present embodiment, a plurality of radiation image detectors (hereinafter also referred to as image sensors) having different sampling frequencies (also referred to as pixel density, resolution, pixel size, pixel pitch, etc.) are connected to the same image processing unit. It is an example of a processed image processing system. In this case, it is necessary to change image processing parameters depending on the resolution of each radiation image detector.
[0057]
In FIG. 9, the first image sensor 90 and the second image sensor 92 are configured such that the grids are detachable, and the first grid determination unit 91 and the second grid determination unit 93 are provided, respectively. Each grid discriminating unit may discriminate whether or not a grid is mounted, and not only the presence or absence of a grid but also the type of grid based on differences in grid frequency, grid ratio, etc. It may be one that is discriminated. When discriminating up to the grid type, as described in the above embodiment, it is possible to use a plurality of types of grids and select image processing parameters according to the type of grid used.
[0058]
The image processing unit 96 acquires information about the resolution unique to each image sensor by a predetermined means. For this reason, each image sensor preferably includes an instruction unit for indicating the information to the external device (image processing unit 96), for example, a transmission unit for transmitting the information. For example, the information is transferred from each image sensor to the image processing unit 96 via the first data interface 94 and the second data interface 95 together with the image information, prior to the transfer of the image information, or at other timing. What should I do?
[0059]
Alternatively, the image processing unit 96 can recognize the identification information (ID information) of each image sensor by the same or other means, and the resolution information of each image sensor is used as an image sensor information table corresponding to the identification information. The image sensor information table storage unit 97 to be stored may be configured so that the image processing unit 96 can refer to it. Typically, the table may be stored in a computer readable memory inside or outside the computer to manage the characteristic information of each image sensor.
[0060]
Further, the image processing unit 96 may be configured to be able to acquire resolution information of each image sensor by a mechanism similar to the system using the grid unit 15 and the grid discrimination circuit 31 in the above-described embodiment. In the present embodiment, for the sake of simplicity, it is assumed that the image sensor that acquired the image data is identified according to which of the data interfaces 94 and 95 is used to acquire the image data. The image processing unit 96 obtains resolution information of the identified image sensor from the image sensor information table, determines an image processing parameter according to the obtained resolution information, and executes image processing based on the determined image processing parameter To do.
[0061]
The flow of processing executed by the image processing system of FIG. 9 will be described using the flowchart of FIG. First, image data is acquired using one of the image sensors 1 and 2 (step S1001).
[0062]
The image processing unit 96 identifies the image sensor that has acquired the image data depending on whether the image data has been acquired through the first data interface 94 or the second data interface 95, and The resolution is acquired by referring to the image sensor information table (step S1002). The resolution information is included in the image sensor information table described above.
[0063]
Next, the image processing unit 96 acquires the presence / absence and / or type information of the grid for the image sensor that has acquired the image data by the same method as in the above-described embodiment (step S1003). The acquisition timing of this information is not limited to this example, but may be any time before image processing is performed. For example, the timing may be immediately before image processing or just before image data acquisition.
[0064]
Next, the image processing unit 96 selects a gain image from the gain image table in accordance with the same idea as the above-described embodiment according to the presence / absence of the grid and / or the type information (step S1004). However, in selecting the gain image in the present embodiment, in addition to the presence / absence and / or type information of the grid, the identification information of the image sensor that acquired the image data is also used. Further, when the image sensor can change the resolution (pixel density), the resolution information is also used in selecting the gain image.
[0065]
Next, the image processing unit 96 selects an image processing parameter from the image processing parameter table (step S1005). This selection is also made under the same concept as in the above embodiment, but in this embodiment, in addition to the presence / absence and / or type information of the grid, the image sensor resolution information is also used using the resolution information of the image sensor. The selection is different from the above-described embodiment. Note that default parameters created in advance are stored in the image processing parameter table, and image processing parameters corresponding to the presence / absence and / or type information of the grid and the resolution information of the image sensor are selected from this table. . Note that the image processing parameters stored in this table are default parameters, and the user can change the parameters depending on individual circumstances (subject characteristics, etc.) during image processing.
[0066]
The necessity of adjusting the image processing parameter in accordance with the resolution of the image sensor will be described with an example. For example, when performing spatial frequency processing (for example, image sharpening processing performed during QA processing) using a filter having a mask size of 7 × 7 pixels, if the pixel size (pixel density) of the applied image data is different, The spatial frequency characteristics of the 7 × 7 pixel filter are also different. However, assuming a clinical image, for example, since the spatial frequency forming the edge of a blood vessel at a predetermined site in the human body is substantially constant, the purpose of image processing is to make the blood vessel easier to see (emphasize). For example, it is desirable that the frequency characteristics of the spatial filter be substantially constant regardless of the resolution (pixel density) of the image sensor.
[0067]
Therefore, in order to perform filter processing having substantially equal frequency characteristics on images with different resolutions, it is necessary to use a filter having a coefficient and / or mask size corresponding to the resolution (pixel density) of the image sensor. . Therefore, in the present embodiment, the image processing parameter is selected according to the presence / absence and / or type information of the grid and the resolution information of the image sensor.
[0068]
Also in the grid erasing process, it is necessary to adjust parameters depending on the resolution of the image sensor. For example, when the Nyquist frequency of the image sensor is Fn and the frequency of the grid is Fg, a spatial frequency Fg if Fg ≦ Fn, and a stripe pattern with a spatial frequency of 2Fn−Fg if Fg> Fn (a stripe caused by the grid). Eye) appears on the image. Therefore, when performing the grid erasure process, the image processing unit 96 calculates or selects the frequency (Fg or 2Fn−Fg) of the grid-derived fringes based on the presence / absence and / or type information of the grid and the resolution information of the image sensor. .
[0069]
Depending on the characteristics of the image sensor, there may be a grid frequency suitable for use. A suitable grid frequency for each image sensor is determined theoretically or experimentally. According to the author's experiment, a grid of about 40 lp / cm is suitable for an image sensor with a 160 micron pixel pitch, and about 60 lp / cm for a sensor with a 100 micron pixel pitch (where lp is a line). meaning of pair). In this case, in the image acquired by each image sensor, each grid forms a different frequency spectrum. In the grid elimination process, a spatial filter that removes frequency components corresponding to the frequency spectrum is used. Therefore, also in this case, the image processing unit 96 calculates or selects a parameter for the grid erasure process based on the presence / absence and / or type information of the grid and the resolution information of the image sensor. Here, when no grid is mounted on the used image sensor (when the grid discriminating circuit 31 discriminates the grid “none”), the parameter of the grid erasure processing is “none”, that is, the grid The erasure process is not executed.
[0070]
Similarly to the above-described embodiment, the image processing unit 96 uses the presence / absence and / or type information of the grid and the resolution information of the image sensor to determine gradation processing parameters (for example, gamma) and image compression parameters. Select etc.
[0071]
Note that the processing parameters adjusted according to the presence / absence and / or type information of the grid and the resolution information of the image sensor and the adjustment method thereof are not limited to those described above, but can be variously changed. At the same time, it is determined based on the wishes of doctors and radiographers.
[0072]
The image processing unit 96 executes image processing based on the parameters determined (calculated or selected) as described above (step S1006).
[0073]
(Other embodiments)
The present invention is a system comprising a plurality of devices (for example, one or more image processing devices, one or more interfaces, one or more radiation imaging devices, one or more X-ray generation devices, etc.), or an image processing device Needless to say, the present invention can be applied to any configuration in which the radiation imaging apparatus is integrated.
[0074]
Another object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and a computer (CPU or MPU, etc.) of the system or apparatus. Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium.
[0075]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.
[0076]
A ROM, floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, or the like can be used as a storage medium for supplying the program code.
[0077]
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS or the like running on the computer based on an instruction of the program code performs actual processing. It goes without saying that the present invention is also configured when a part or all of the above is performed and the functions of the above-described embodiment are realized by the processing.
[0078]
Further, after the program code read from the storage medium is written in a memory provided in an extension function board inserted in the computer or a function extension unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the present invention is also configured when a CPU or the like provided in an expansion board, a function expansion unit or the like performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0079]
When the present invention is applied to the above-described program code and computer-readable storage medium, the program code is, for example, a program code corresponding to the flowchart shown in FIG. 10 described in the above-described embodiment, and The storage medium stores, for example, a program code corresponding to the flowchart.
[0080]
FIG. 11 shows an example of the configuration of the computer function 1100 described above.
[0081]
As shown in FIG. 11, the computer function 1100 includes a CPU 1101, a ROM 1102, a RAM 1103, a keyboard controller (KBC) 1105 for a keyboard (KB) 1109, and a CRT controller (CRT) 1110 as a display unit (display). CRTC) 1106, a disk controller (DKC) 1107 for a hard disk (HD) 1111 and a floppy disk (FD) 1112, and a network interface card (NIC) 1108 connected to an arbitrary network 1120 via a system bus 1104 It is configured to be communicably connected to each other.
[0082]
The CPU 1101 comprehensively controls each component connected to the system bus 1104 by executing software (program code or the like) stored in the ROM 1102 or the HD 1111 or software supplied from the FD 1112.
[0083]
That is, the CPU 1101 reads out from the ROM 1102 or the HD 1111 or the FD 1112 and executes a processing program according to a predetermined processing sequence, thereby performing control for performing the operation in the above-described embodiment.
[0084]
The RAM 1103 functions as a main memory or work area for the CPU 1101.
[0085]
The KBC 1105 controls an instruction input from a KB 1109 or a pointing device (not shown).
[0086]
The CRTC 1106 controls display by a display device such as a CRT 1110.
[0087]
The DKC 1107 controls access to the HD 1111 or the FD 1112 that stores a boot program, various application software, an editing file, a user file, a network management program, a processing program according to the above-described embodiment, and the like.
[0088]
The NIC 1108 exchanges data bidirectionally with devices or systems on the network 1120.
[0089]
The present invention is not limited to the above-described embodiments, but rather various changes and modifications are possible within the spirit and scope of the present invention. Therefore, in order to notify the public of the scope of the present invention, the aforementioned claims are prepared.
[0090]
【The invention's effect】
As described above, according to the present invention, a plurality of image sensors having different pixel densities can be selectively used, and a radiation image processing apparatus for performing image processing according to information on the pixel density and the grid, radiation An image processing system, a radiation imaging system, a radiation imaging apparatus, a radiation image processing method, a computer-readable storage medium, and a program can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a radiation imaging apparatus.
FIG. 2 is a plan view of the radiation imaging section
[Fig. 3] Front view of the grid unit
4 is a cross-sectional view taken along line AA in FIG.
FIG. 5 is a graph showing the current value flowing through the motor with respect to the elapsed time.
FIG. 6 is a block diagram of an image processing unit.
FIG. 7 is a diagram for explaining an image processing flow by the image processing unit;
FIG. 8 is a diagram for explaining an image processing flow by the image processing unit;
FIG. 9 is a diagram for explaining a system configuration;
10 is a diagram for explaining a processing flow by the system of FIG. 9;
FIG. 11 is a block diagram illustrating a configuration of a computer that can execute a program related to the function or operation of the embodiment;
[Explanation of symbols]
94 First data interface
95 Second data interface
96 Image processing unit
97 Image sensor information table

Claims (11)

In a radiographic image processing apparatus that processes radiographic image data from a radiographing device that detects a radiographic image transmitted through a grid for removing scattered radiation,
Grid information acquisition means for acquiring information on the type of the scattered radiation removal grid mounted on the radiation imaging device;
Pixel density information acquisition means for acquiring information on the pixel density of the image sensor in the radiation imaging device;
A radiographic image processing apparatus comprising: an image processing unit that calculates or selects a frequency of a grid-derived fringe based on the type of the grid and the pixel density, and executes a grid erasing process based on the frequency . The image processing means is configured to execute at least one of gain correction processing, frequency processing, gradation processing, and image compression processing by changing processing parameters according to the grid type and the pixel density. The radiographic image processing apparatus according to claim 1, wherein The radiographic image processing apparatus according to claim 1, wherein the grid erasing process is a band cut filter process having a frequency characteristic determined by the calculation or a selected frequency . A radiation image processing system in which a plurality of devices are communicably connected to each other, and each component constituting the radiation image processing device according to any one of claims 1 to 3 is provided. Image processing system. A radiation imaging system comprising: the radiation image processing apparatus according to any one of claims 1 to 3; and the radiation imaging device. Grid information presentation means for presenting information related to the scattered radiation removal grid in the radiation imaging apparatus to an external device;
The radiation image processing apparatus according to claim 1, further comprising: a pixel density information presenting unit that presents information related to a pixel density of the radiation image detector in the radiation imager to an external device. In a radiographic image processing method for processing radiographic image data from a radiographer that detects a radiographic image transmitted through a grid for removing scattered radiation,
A grid information acquisition step for acquiring information related to the type of the scattered radiation removal grid mounted on the radiation imaging device;
A pixel density information acquisition step of acquiring information relating to a pixel density of an image sensor in the radiation imaging device;
A radiation image processing method comprising: an image processing step of calculating or selecting a frequency of a grid-derived fringe based on the type of the grid and the pixel density, and executing a grid erasing process based on the frequency . The radiographic image processing apparatus according to claim 1, the radiographic image processing system according to claim 4, the radiographic imaging system according to claim 5, and the radiographic imaging apparatus according to claim 6. A computer-readable storage medium storing a program for causing a computer to realize the functions of the apparatus or system described in the paragraph. A computer-readable storage medium storing a program for causing a computer to execute the operation of the radiographic image processing method according to claim 7. Any one of the radiation image processing apparatus according to claim 1, the radiation image processing system according to claim 4, the radiation imaging system according to claim 5, and the radiation imaging apparatus according to claim 6. A program for causing a computer to realize the functions of the apparatus or system described in the paragraph. A program for causing a computer to execute the operation of the radiological image processing method according to claim 7.

Images