JP4280334B2 - Irradiation squeezing presence / absence determination device, method, and computer-readable storage medium - Google Patents

Description

【００３３】
次に右端点抽出手段９０３は（５）式に従い右照射端ｘ２を抽出する（ステップＳ１０３）。
【００３４】
【数２】

【００３５】
ただし、Ｌｅｎｇｔｈは画像データの横軸の長さを示す。
【００３６】
次に第３の判定手段９０４は予め求められた照射端と式（４）、（５）で求められた照射端とを比較し、｜ｘ１−ｘａ｜≦Ｔｈ８かつ｜ｘ２−ｘｂ｜≦Ｔｈ８ならば照射しぼり無しと判定し、ｆｌｇ３＝１とする。それ以外の場合は照射しぼり有りと判定し、ｆｌｇ３＝２とする（ステップＳ３０４）。
【００３７】
また、図１０では説明していないが、｜ｘ１−ｘａ｜＜Ｔｈ７かつ｜ｘ２−ｘｂ｜＜Ｔｈ７ならば完全にしぼり無しとし、ｆｌｇ３１＝１、ｆｌｇ３＝１とする。さらにＴｈ７≦｜ｘ１−ｘａ｜＜Ｔｈ８かつＴＨ７≦｜ｘ２−ｘｂ｜＜Ｔｈ８ならば、しぼり無しの可能性大としてｆｌｇ３１＝２、ｆｌｇ３＝１とする。また、Ｔｈ８≦｜ｘ１−ｘａ｜＜Ｔｈ９かつＴＨ８≦｜ｘ２−ｘｂ｜＜Ｔｈ９ならば、しぼり有りの可能性大としてｆｌｇ３１＝３、ｆｌｇ３＝４とする。そして最後に、Ｔｈ９≦｜ｘ１−ｘａ｜かつＴｈ９≦｜ｘ２−ｘｂ｜ならば、完全にしぼり有りとしてｆｌｇ３１＝４、ｆｌｇ３＝２とする。
【００３８】
尚、Ｔｈ７，Ｔｈ８，Ｔｈ９は近似幅を示す定数で、Ｔｈ７＜Ｔｈ８＜Ｔｈ９なる関係がある。Ａ、Ｂ、Ｃ端についても同様に判定する。
また照射端を抽出する場合にさらに条件を付加して、２次差分値が一定閾値以下となる条件を置いてもよい。さらに、照射端での濃度変化が急峻な場合には、照射端として１次微分、２次微分、さらなる高次微分の値を２次差分の代わりに用いてよい。この場合、各値の絶対値が一定閾値以上の箇所を照射端候補とする。
【００３９】
以上のようにこのしぼり有無判定部１０３によれば、判定基準として２次差分値を用いているため、Ｘ線の透過率の悪い物体に対しても、Ｘ線の直接照射される領域とそうでない領域との境界点を精度よく抽出することができる。そのため、画像端部に腹部などのＸ線透過率の低い部位が覆いかぷさっていても、照射しぼりの有無を精度よく抽出することができる効果がある。
【００４０】
次に判定部１０４による各しぼり有無判定部１０１〜１０３の判定結果の統合方法について説明する。
本実施の形態の統合法則は、判定部１０４により各しぼり有無判定部１０１〜１０３の判定結果のうち多数の判定結果を採用するものである。具体的に図１１のフローチャートに従い説明する。
まず第１のしぼり有無判定部１０１の判定がしぼり有り無しか判定し（Ｓ１１０１）、しぼり無しならば第２のしぼり有無判定部１０２の判定結果を参照し、しぼり無しなら判定部１０４の判定結果をしぼり無しとして処理を終了する。
【００４１】
第２のしぼり有無判定部１０２の判定結果がしぼり有りなら第３のしぼり有無判定部１０３の判定結果を参照し、しぼり無しなら判定部１０４の判定結果をしぼり無しとし、しぼり有りなら判定結果をしぼり有りとして処理を終了する。
【００４２】
また第１のしぼり有無判定部１０１の判定がしぼり有りならば第２のしぼり有無判定部１０２の判定結果を参照し、しぼり有りなら判定部１０４の判定結果をしぼり有りとして処理を終了する。第２のしぼり有無判定部１０２の判定結果がしぼりなしなら第３のしぼり有無判定部１０３の判定結果を参照し、しぼり無しなら判定部１０４の判定結果をしぼり無しとし、しぼり有りなら判定結果をしぼり有りとして処理を終了する。
【００４３】
本実施の形態では、しぼり有無判定部を３種しか用いてないが、それ以上の数に拡張してもよい。また、本実施の形態で用いた以外の照射しぼりの有無を判定するアルゴリズムを用いてもよい。
【００４４】
以上のように本実施の形態では、複数のしぼり有無判定部の結果を統合するので、判定精度が上がる効果がある。さらに、複数のしぼり有無の判定結果のうち多数の判定に従って最終判定をするので、しぼり有無判定部を一つしか使わない場合より精度が上がる効果がある。
【００４５】
次に第２の実施の形態による各しぼり有無判定部１０１〜１０３の結果の統合方法について図１２のフローチャートを用いて説明する。
本実施の形態では、第１のしぼり有無判定部１０１の結果が完全にしぼり無しならぱ判定部１０４の判定結果をしぼり無しとして処理を終了する。
【００４６】
また、第１のしぼり有無判定部１０１の結果が完全にしぼり無し以外ならステップ１２０２の判定に進む（Ｓ１２０１）。次にステップＳ１２０２では、第１のしぼり有無判定蔀１０１の結果が完全にしぼり有りならば、判定部１０４の判定結果をしぼり有りとして処理を終了し、それ以外ならばステップＳ１２０３に進む。ステップＳ１２０３では、第１のしぼり有無判定部１０１の結果がしぼり無しの可能性大がどうか判定し、しぼり無しの可能性大ならばステップＳ１２０４に進み、それ以外の場合はステップＳ１２０６に進む。
【００４７】
そして、第２のしぼり有無判定部１０２の判定結果がしぼり無しならば判定部１０４の判定結果をしぼり無しとして処理を終了し、それ以外の場合はステップＳ１２０５に進む（Ｓ１２０４） 。そして、Ｓ１２０５では第３のしぼり有無判定部１０３の結果がしぼり無しならば判定部１０４の結果をしぼり無しとし、しぼり有りならば判定部１０４の結果をしぼり有りとして処理を終了する。
尚、各しぼり有無の判定部１０１〜１０３のアルゴリズムを順列的に入れ替えて図１２と同一の処理を行ってもよい。
【００４８】
本実施の形態によれば、各しぼり有無判定部の結果にしぼり有無の判定に対し確実性の高い判定が出る場合は、その判定結果を採用することでより判定精度が上がる効果がある。
また、各しぼり有無判定部の判定の確実性が低い場合には、各しぼり有無判定部の判定結果のうち多数を占める判定結果を採用するためより判定精度が上がる効果がある。
【００４９】
次に第３の実施による各しぼり有無判定部１０１〜１０３の結果の統合方法について図１３を用いて説明する。
本実施の形態では、各しぼり有無判定部のうちの一つの判定部の判定結果が完全にしぼり有りと判定した場合、判定部１０４の判定結果をしぼり有りとして処理を終了する。
各しぼり有無判定部の判定結果がいずれも完全にしぼり有りでなかった場合は、図１１に示す第１の実施の形態と同様の処理を行う。
【００５０】
本実施の形態によれば、各しぼり有無の判定結果のうち、確実な判定結果があればその結果を採用するので、判定精度が上がる効果がある。さらに、各しぼり有無の判定結果のうち、確実な判定結果が無い場合には、第１の実施の形態と同様の処理を行うことにより判定精度が上がる効果がある。
【００５１】
次に第４の実施の形態による各しぼり有無判定部１０１〜１０３の結果の統合方法について図１４を用いて説明する。
本実施の形態では、各しぼり有無判定部のうち一つの判定部の判定結果が完全にしぼり無しと判定した場合、判定部１０４の判定結果をしぼり無しとして処理を終了する。
各しぼり有無の判定部の判定結果がいずれも完全にしぼり無しでなかった場合は、図１１に示す第１の実施の形態と同様の処理を行う。
【００５２】
本実施の形態によれば、各しぼり有無の判定結果のうち、確実な判定結果があればその結果を採用するので、判定精度が上がる効果がある。さらに、各しぼり有無の判定結果のうち、確実な判定結果が無い場合には、第１の実施の形態と同様の処理を行うことにより判定精度が上がる効果がある。
【００５３】
次に第５の実施の形態を説明する。
本実施の形態では、各しぼり有無判定部の結果を数値化し、その結果の合計値からしぼりの有無を判定する。例えばｆｌｇ１１が１ならば判定値ｈ１＝２、ｆｌｇ１１が２ならば判定値ｈ１＝１、ｆｌｇ１１が３ならば判定値ｈ１＝−１、ｆｌｇ１１が４ならば判定値ｈ１＝−２とする。同様に、ｆｌｇ２１が１ならば判定値ｈ２＝２、ｆｌｇ２１が２ならば判定値ｈ２＝１、ｆｌｇ２１が３ならば判定値ｈ２＝−１、ｆｌｇ２１が４ならば判定値ｈ２＝−２とする。
【００５４】
同様に、ｆｌｇ３１が１ならば判定値ｈ３＝２、ｆｌｇ３１が２ならば判定値ｈ３＝１、ｆｌｇ３１が３ならば判定値ｈ３＝−１、ｆｌｇ３１が４ならば判定値ｈ３＝−２とする。そしてｈ１＋ｈ２＋ｈ３の合計値から判定部１０４がしぼりの有無を判定する。例えば合計値が０以上の場合にしぼり無し、０より下の場合にしぼり有りと判定する。
尚、本実施の形態においては、しぼり有無判定部の数を増やしてもよい。また、判定の数値化を変更してもよい。
【００５５】
本実施の形態によれば、各しぼり有無の判定部の結果を数値化して総合的に判定できるため、判定精度が上がる効果がある。
【００５６】
次に第６の実施の形態を説明する。
第１のしぼり有無判定部１０１の出現頻度計算手段４０２で計算された出現頻度、第２のしぼり有無判定部１０２の第２の判定手段７０５で計算された照射端点の分散値、第３のしぼり有無判定部１０３の第３の判定手段９０４で計算される｜ｘ１−ｘａ｜、｜ｘ２−ｘ１｜の合計値を説明変数とし、しぼりの有無を目的変数として重回帰分析を行い線形式を作成する。例えば目的変数をしぼりが有れば１、無ければ０とする。そして未知な画像が入力されたならば、上記説明変数を計算し、上記線形式の値を求め、例えば線形式の値が０．５以上ならしぼり有り、Ｏ．５よリ下ならばしぼり無しとする。
【００５７】
尚、ここでは線形回帰式を用いたが、ニューラルネット、エージェント等を用いてもよい。
またしぼり有無判定部は３つに限るものではない。
【００５８】
本実施の形態によれば、各しぼり有無判定部位の結果を統計的に判定結果に反映することが可能であり、より判定精度が上がる効果がある。また関数の作成にニューラルネットを用いた場合には、非線型な統計分布を反映することが可能でより判定精度が上がる効果がある。
【００５９】
次に本発明による記憶媒体について説明する。
図１、図４、図７、図９の各ブロックから成るシステムを、ＣＰＵ、ＲＯＭ等のメモリを含むコンピュータシステムで構成する場合、上記メモリは本発明による記憶媒体を構成する。この記憶媒体には、図５、図６、図８、図１０、図１１等のフローチャートについて前述した動作を制御するための処理手順を実行するためのプログラムが記憶される。
【００６０】
また、この記憶媒体としては、ＲＯＭ、ＲＡＭ等の半導体メモリ、光ディスク、光磁気ディスク、磁気媒体等を用いてよく、これらをＣＤ−ＲＯＭ、フロッピィディスク、磁気媒体、磁気カード、不揮発性メモリカード等に構成して用いてよい。
【００６１】
従って、この記憶媒体を上記各図に示したシステムや装置以外の他のシステムや装置で用い、そのシステムあるいはコンピュータがこの記憶媒体に格納されたプログラムコードを読み出し、実行することによっても、前述した各実施の形態と同等の機能を実現できると共に、同等の効果を得ることができ、本発明の目的を達成することができる。
【００６２】
また、コンピュータ上で稼働しているＯＳ等が処理の一部又は全部を行う場合、あるいは、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拡張機能ユニット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いて、上記拡張機能ボードや拡張機能ユニットに備わるＣＰＵ等が処理の一部又は全部を行う場合にも、各実施の形態と同等の機能を実現できると共に、同等の効果を得ることができ、本発明の目的を達成することができる。
【００６３】
【発明の効果】
以上説明したように、本発明によれば、各判定結果のうち、確実な判定結果があればその結果を採用するので、判定精度が上がる効果がある。さらに、各判定結果のうち、確実な判定結果が無い場合には、複数のしぼり有無の判定結果のうち多数の判定に従って最終判定をするので、しぼり有無判定基準を一つしか使わない場合より精度が上がる効果がある。
【００６８】
さらに、本発明の他の特徴によれば、判定基準として画像全体のＭＡＸ値から決められる濃度の出現頻度を用いることにより、照射端部に撮影対象がかかっても安定した判定が行える効果がる。また、放射線量の強弱の影響を受けず、放射線量が少ない場合や、画像端部全体を撮影対象が覆う場合にも安定して判定が行える効果がある。
【００６９】
また、判定基準として、複数の照射端点の座標値の分散を用いることにより、その値を基準として照射しぼりの有無をうまく抽出できる効果がある。さらに、２次差分値を用いることにより、Ｘ線の透過率の悪い物体に対しても、Ｘ線の直接照射される領域とそうでない領域との境界点を精度よく判定することができる。そのため、画像端部に腹部等のＸ線透過率の低い部位がかぶさっていても、照射しぼりの有無を精度よく抽出することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態を示すブロック図である。
【図２】照射しぼり無しで撮影した手のＸ線画像を示す構成図である。
【図３】照射しぼり有りで撮影した手のＸ線画像と照射端部Ａを示す構成図である。
【図４】第１のしぼり有無判定部の構成を示すブロック図である。
【図５】第１のしぼり有無判定部の処理の流れを示すフローチャートである。
【図６】第２のしぼり有無判定部の判定領域を示す構成図である。
【図７】第２のしぼり有無判定部の構成を示すブロック図である。
【図８】第２のしぼり有無判定部の処理の流れを示すフローチャートである。
【図９】第３のしぼり有無判定部の構成を示すブロック図である。
【図１０】第３のしぼり有無判定部の処理の流れを示すフローチャートである。
【図１１】第１の実施の形態の処理の流れを示すフローチャートである。
【図１２】第２の実施の形態の処理の流れを示すフローチャートである。
【図１３】第３の実施の形態の処理の流れを示すフローチャートである。
【図１４】第４の実施の形態の処理の流れを示すフローチャートである。
【符号の説明】
１０１ 第１のしぼり有無判定部
１０２ 第２のしぼり有無判定部
１０３ 第３のしぼり有無判定部
１０４ 判定部
４０１ 第１の特性値算出手段
４０２ 第１の出現頻度計算手段
４０３ 第１の判定手段
７０１ 座標指示手段
７０２ 特性値抽出手段
７０３ 端点抽出手段
７０４ 記憶手段
７０５ 第２の判定手段
９０１ ２次差分値計算手段
９０２ 左端点抽出手段
９０３ 右端点抽出手段
９０４ 第３の判定手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an irradiation-threshold presence / absence determination device and method for determining the presence / absence of irradiation-threshold from an image taken by an imaging device with radiation-threshold-down, and a computer-readable storage medium used in this device, in particular. This is suitable for use in determining the presence or absence of irradiation from the appearance frequency in the end region of the density value determined from the characteristic value obtained from the above.
[0002]
[Prior art]
With recent advances in digital technology, a radiation image is converted into a digital image signal, image processing is performed on the digital image signal, and the image is displayed on a CRT or printed out. By the way, in radiographic image capturing, for humanitarian reasons, in order to prevent scattering from unnecessary areas and to prevent reduction of contrast, it is common to perform irradiation squeezing that irradiates only the necessary areas. Is. In performing image processing, it is common to determine processing parameters from the distribution of density values and perform image processing based on the determined parameters. However, when the irradiation area is not limited, so-called unnecessary information outside the region of interest is used for determination of the image processing parameter, which causes a problem that appropriate image processing cannot be performed.
[0003]
Therefore, it is necessary to extract an irradiation region and determine an image processing parameter from information on only the region of interest. As a method for extracting the irradiation region, for example, a method of differentiating the image density value and determining the irradiation end from the value, or a region of the base field outside the irradiation region as shown in Japanese Patent Publication No. 6-90412, A method is known in which this bottom field is approximated by a first-order approximation expression, and the irradiation end is determined from the difference between the actual density value and the value of the first-order approximation expression.
[0004]
However, each of the above-mentioned irradiation end extraction methods is a method that is based on the assumption that there is an irradiation squeeze, and in order to use each irradiance end extraction method, it is necessary to determine whether or not there is an irradiation squeeze as preprocessing.
[0005]
As a method for determining the presence or absence of irradiation squeezing, as shown in US Pat. No. 5,091,970, the density average, intermediate value, etc. at the center of the image are compared with the density average value at the edge of the image. If the density value is below a certain value, there is a method of squeezing.
[0006]
[Problems to be solved by the invention]
However, in the method of US Pat. No. 5,091,970, when an imaging region is applied to the edge of the image when the irradiation is not performed, the area of the imaging region is affected by the area of the imaging region applied to the image edge and the transmittance of radiation. Average concentration varies. For this reason, there has been a problem of erroneously determining that there is irradiation even though irradiation is not performed.
In addition, when the irradiation dose is small, there is a problem that there is no difference in density between the center of the image and the edge of the image, and there is a problem of erroneous determination that there is irradiation even though there is no irradiation.
[0007]
The present invention has been made to solve the above-described problems, and an object of the present invention is to make it possible to accurately determine the presence or absence of irradiation.
[0008]
[Means for Solving the Problems]
The irradiation squeezing presence / absence determination device according to the present invention includes at least two squeezing presence / absence determination units having different criteria for determining the presence / absence of irradiation squeezing with respect to a radiographic image, and the first squeezing determination unit among the plurality of squeezing presence / absence determination units. If the presence / absence determining means determines that there is a restriction, it is determined that there is a restriction. Otherwise, the presence / absence of the restriction is determined based on the determination result of the restriction presence / absence determination means that is different from the first restriction presence / absence determination means. And an integrated determination unit.
In addition, another feature of the irradiation squeezing presence / absence determination device according to the present invention is that at least two squeezing presence / absence determination means having different criteria for determining the presence / absence of irradiation squeezing with respect to a radiographic image, Of the determining means, when the first squeezing presence / absence determining means determines that there is no squeezing, it is determined that there is no aperture, and in other cases, the determination result of the squeezing presence / absence determining means that is different from the first squeezing presence / absence determining means. And integrated determination means for determining the presence or absence of an aperture based on the above.
[0009]
The irradiation squeezing presence / absence determination method of the present invention includes a squeezing presence / absence determination step in which the presence / absence of squeezing is determined by at least two squeezing presence / absence determination means different from each other in the determination criterion of the presence or absence of radiation squeezing with respect to a radiographic image, Of the squeezing presence / absence determining means, if the first squeezing presence / absence determining means determines that there is a squeezing, it is determined that there is a squeezing, and otherwise, the squeezing presence / absence determining means is different from the first squeezing presence / absence determining means. An integrated determination step of determining the presence or absence of an aperture based on the determination result.
Another feature of the present invention is a method for determining the presence / absence of squeezing by means of at least two squeezing / non-squeezing determining means for determining the presence / absence of radiation squeezing for radiographic images. Of the plurality of squeezing presence / absence determination means, when the first squeezing presence / absence determination unit determines that there is no squeezing, it is determined that there is no squeezing, and in other cases, the first squeezing presence / absence determination unit is determined. And an integrated determination step of determining the presence or absence of an aperture based on a determination result of a squeezing presence / absence determination unit different from the determination unit.
[0010]
The storage medium according to the present invention includes a squeezing presence / absence determination step for determining the presence / absence of squeezing by at least two squeezing / non-squeezing determination means having different criteria for determining the presence / absence of irradiation irradiation with respect to a radiographic image, and the plurality of squeezing / non-squeezing determinations Among the means, when the first squeezing presence / absence determining means determines that there is squeezing, it is determined that there is a squeezing, and in other cases, the determination result of the squeezing presence / absence determining means different from the first squeezing presence / absence determining means is used. A program for causing a computer to execute an integrated determination step for determining whether or not there is an aperture based on the program is stored.
Another feature of the storage medium according to the present invention is that the presence / absence of the squeezing is determined by at least two squeezing / non-squeezing determining means having different criteria for determining the presence / absence of the irradiation squeezing for the radiographic image. Of the plurality of squeezing presence / absence determining means, if the first squeezing presence / absence determining means determines that there is no squeezing, it is determined that there is no aperture, and otherwise, the first squeezing presence / absence determining means A program for causing a computer to execute an integrated determination step of determining the presence or absence of a diaphragm based on the determination results of different squeezing presence / absence determination means is characterized.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an irradiation-thinning presence / absence determination device according to the first embodiment of the present invention.
In FIG. 1, reference numeral 101 denotes a first squeezing presence / absence determination unit, 102 denotes a second squeezing presence / absence determination unit, 103 denotes a third squeezing presence / absence determination unit, and 104 denotes first to third squeezing presence / absence determination units 101 to 101. The determination part which determines the presence or absence of squeezing integratedly from the determination result of 103 is shown.
[0012]
Next, each of the squeezing presence / absence determining units 101 to 104 will be described sequentially.
FIG. 2 shows an X-ray image of a hand taken without irradiation.
FIG. 3 shows an X-ray image taken with irradiation, and a region A shows an image end portion having a horizontal width dx and a vertical width dy.
[0013]
FIG. 4 is a block diagram showing the configuration of the first squeezing presence / absence determination unit 101. In FIG. 4, 401 is a second characteristic value calculation means for calculating a first characteristic value from the entire image, and 402 is a first characteristic. First appearance frequency calculation means for calculating the frequency at which the density value determined based on the characteristic value calculated by the value calculation means 401 appears at the image edge A, and 403 is the first appearance frequency calculation means 402. It is the 1st determination means which determines the presence or absence of irradiation squeezing from the calculated value.
[0014]
Next, the operation of the first squeezing presence / absence determining unit 101 will be described with reference to the flowchart of FIG. Here, for example, a case will be described in which it is determined whether or not there is irradiation at the left end.
The first characteristic value calculation unit 401 calculates the MAX value of the entire image. The MAX value here may be the upper part of the cumulative histogram of the entire image, for example, the 5% point, or the image density values may be sorted and used as the upper part (step S501).
[0015]
Next, the first appearance frequency calculation unit 402 calculates the appearance frequency at the image end A of a certain ratio of the MAX value calculated by the first characteristic value calculation unit 401, for example, a density value of 90% or more ( Step S502).
[0016]
Next, if the appearance frequency calculated by the first appearance frequency calculation means 402 is larger than a certain value Th1, the first determination means 403 determines that there is no irradiation completely and sets flg11 = 1 and flg1 = 1 ( Step S503). If the appearance frequency is equal to or less than Th1 and greater than Th2, the possibility of no squeezing is assumed to be large, and flg11 = 2 and flg1 = 1 are set (step S504). If it is equal to or less than Th2 and greater than Th3, the possibility of squeezing is set, and flg11 = 3 and flg = 2 are set (S505). If it is less than Th3, no squeeze is made. Here, for example, Th1 = 0.3, Th2 = 0.1, and Th3 = 0.05.
[0017]
As described above, according to the first reduction presence / absence determination unit 101, the presence / absence of irradiation reduction is determined using the appearance frequency of the density at the image edge determined from the MAX value of the entire image as a determination criterion. There is an effect that a stable determination can be made even if an object to be photographed is applied to the part. In addition, there is an effect that the determination can be performed stably even when the radiation dose is small or when the imaging target covers the entire image edge without being affected by the intensity of the radiation dose.
[0018]
Next, the second determination unit 102 will be described.
FIG. 6 shows an X-ray image taken with irradiation squeezed, and Xa and Xb show the positions of the irradiation end with respect to the horizontal axis. Regions A, B, C, and D indicate the edge of the image, A and B indicate regions that are irradiated, and C and D indicate regions that are not irradiated.
[0019]
FIG. 7 is a block diagram illustrating a configuration of the second determination unit 102.
In FIG. 7, reference numeral 701 denotes a coordinate instruction means for instructing coordinates for extracting an irradiation end, and reference numeral 702 denotes a second characteristic value used for determining the irradiation end point from the one-dimensional data of the coordinates instructed by the coordinate instruction means 701. Characteristic value extraction means 703, an end point extraction means for extracting an irradiation end point from the characteristic value calculated by the second characteristic value extraction means 702, and a storage for storing the coordinates of the irradiation end point extracted by the end point extraction means 703. A means 705 is a second determination means for determining the presence or absence of irradiation from the value of the coordinates of the irradiation end point stored in the storage means 704.
[0020]
Next, operation | movement of the 2nd determination part 102 is demonstrated using the flowchart of FIG. Here, for example, a case where it is determined whether or not there is irradiation at the lower end will be described.
A coordinate instruction unit 701 indicates the coordinates of a plurality of X-axis fields between Xa and Xb shown in FIG. For example, in the present embodiment, coordinates (i = 1 to 10) obtained by equally dividing Xa and Xb into 10 parts are used (step S801).
[0021]
Next, the second characteristic value extracting unit 702 calculates the secondary difference value SSi (y) from the one-dimensional data of the coordinates indicated by the coordinate indicating unit 701 according to the calculation formula shown by the formula (1) (step S802). . Here, i is a coordinate number indicated by the coordinate instruction means 801. Further, fi (y) indicates a one-dimensional data string that crosses vertically between Xa and Xb, and y indicates the coordinates thereof. d is a constant indicating the difference distance.
SSi (y) = fi (y−d) 1-2 × fi (y) + fi (y + d) (1)
[0022]
The end point extraction unit 803 extracts the irradiation end yi according to the equation (2) (step S803).
SS (yi) = min {SS (yi) 0 ≦ y ≦ Length} (2)
[0023]
And the memory | storage means 704 memorize | stores the coordinate yi of an irradiation end (step S804).
The above steps S801 to S804 are repeated from 1 = 1 to 10. Here, Length indicates the length of the horizontal axis of the image data.
[0024]
Next, the second determination unit 705 calculates the average value of the coordinates of the irradiation end point stored in the storage unit 704 (step S805), and calculates the dispersion value Bv of the irradiation end point (step S806). If the dispersion value Bv is equal to or greater than a certain number Th4, no irradiation is performed, and otherwise, irradiation is performed (step S807).
[0025]
Although not described in FIG. 8, if the variance value is greater than Th4, it is determined that flg21 = 1 and flg2 = 1 are complete, and if it is less than Th4 and greater than Th5, there is a large possibility of no squeeze. And flg21 = 2 and flg2 = 1. If it is equal to or less than Th5 and greater than Th6, it is determined that there is a large possibility of squeezing, and flg21 = 3 and f1g2 = 2. Finally, if it is less than Th6, it is determined that flg21 = 4 and flg2 = 2 and that there is complete squeezing.
[0026]
Th4, Th5, and Th6 are experimentally determined teachings, and have a relationship of Th4>Th5> Th6. If the irradiation end is obtained in a plurality of rows and there is an irradiation squeeze (lower part), the plurality of end points are arranged on substantially the same horizontal axis, so the variance Bv becomes small. If there is no irradiation squeezing, the coordinates of the irradiation end point vary. The variance value Bv increases.
[0027]
In the above description, the secondary difference is used. However, when the density at the irradiation end changes sharply, a primary difference or a high-order difference may be used. In that case, a value is searched from the edge of the image, and a point where a value equal to or greater than a certain threshold value first appears is set as an irradiation end candidate.
Further, although the variance value is used as the determination index by the determination means, the same effect can be obtained by using an index indicating the discrete degree of other frequencies such as standard deviation.
[0028]
As described above, according to the second squeezed presence / absence determination unit 102, since the variance of the coordinate values of a plurality of irradiation end points is used as a determination criterion, there is an effect that the presence / absence of squeezing can be well extracted based on that value. In addition, since the secondary difference value is used, the boundary point between the area directly irradiated with X-rays and the area not irradiated can be accurately determined even for an object with low X-ray transmittance. Therefore, even if a portion having a low X-ray transmittance, such as the abdomen, covers the edge of the image, it is possible to accurately extract the presence of irradiation.
[0029]
Next, the third squeezing determination unit 103 will be described.
FIG. 9 is a block diagram illustrating a configuration of the third squeezing determination unit 103.
In FIG. 9, reference numeral 901 denotes a secondary difference value calculation means for calculating the secondary difference value of the one-dimensional image data, and 902 denotes a left end point of the irradiation area based on the secondary difference value calculated by the secondary difference value calculation means 901. 903 is a right end point extracting means for extracting the right end point of the irradiation area based on the secondary difference value calculated by the secondary difference value calculating means 901, and 904 is extracted by the left end point extracting means 902 The degree of approximation between the left end point and the right end point extracted by the right end point extracting means 903 and the left and right end points of the irradiation area obtained in advance is determined. If the degree of approximation is high, it is determined that there is no irradiation, and the degree of approximation Is a third determination means for determining that there is irradiation squeezing.
[0030]
Next, the operation of the third squeezing presence / absence determining unit 103 will be described with reference to the flowchart of FIG. Here, for example, a case will be described in which it is determined whether or not there is irradiation at the lower end (portion in FIG. 6C).
The secondary difference value calculation means 901 calculates the secondary difference value SS (x) according to the calculation formula shown by the formula (3) (step S1001). Here, f (x) indicates a one-dimensional data string traversing the region C in the horizontal direction, and x indicates the coordinates. d is a constant indicating the difference distance.
SS (d) = f (x−d) 1 × 2 × f (x) + f (x + d) (3)
[0031]
The left end point extraction means 902 extracts the left irradiation end x1 according to the equation (4) (step S1002). Here, the bar x is a coordinate on the horizontal axis in the left and right irradiation ends (coordinate between Xa and Xb in FIG. 6).
[0032]
[Expression 1]

[0033]
Next, the right end point extracting means 903 extracts the right irradiation end x2 according to the equation (5) (step S103).
[0034]
[Expression 2]

[0035]
Here, Length indicates the length of the horizontal axis of the image data.
[0036]
Next, the third determination unit 904 compares the irradiation end obtained in advance with the irradiation end obtained by the equations (4) and (5), and | x1-xa | ≦ Th8 and | x2-xb | ≦ Th8. Then, it is determined that there is no irradiation squeeze, and flg3 = 1. In other cases, it is determined that there is irradiation and flg3 = 2 is set (step S304).
[0037]
Although not described in FIG. 10, if | x1-xa | <Th7 and | x2-xb | <Th7, it is assumed that there is no squeeze and flg31 = 1 and flg3 = 1. Further, if Th7 ≦ | x1−xa | <Th8 and TH7 ≦ | x2−xb | <Th8, it is assumed that flg31 = 2 and flg3 = 1 as the possibility of no squeezing. Further, if Th8 ≦ | x1−xa | <Th9 and TH8 ≦ | x2−xb | <Th9, it is assumed that flg31 = 3 and flg3 = 4 as the possibility that there is a reduction. Finally, if Th9 ≦ | x1−xa | and Th9 ≦ | x2−xb |, it is assumed that there is a complete reduction, and flg31 = 4 and flg3 = 2.
[0038]
Th7, Th8, and Th9 are constants indicating approximate widths, and have a relationship of Th7 <Th8 <Th9. The same determination is made for the A, B, and C ends.
In addition, when extracting the irradiation end, a condition may be added so that the secondary difference value is equal to or less than a certain threshold value. Further, when the density change at the irradiation end is steep, the values of the first derivative, the second derivative, and the further higher derivative may be used as the irradiation end instead of the secondary difference. In this case, a point where the absolute value of each value is equal to or greater than a certain threshold is set as an irradiation end candidate.
[0039]
As described above, according to the squeezing presence / absence determination unit 103, since the secondary difference value is used as a determination criterion, even an object with low X-ray transmittance is considered to be an area directly irradiated with X-rays. It is possible to accurately extract boundary points with non-regions. Therefore, there is an effect that the presence / absence of irradiation squeezing can be accurately extracted even when the image end portion is covered with a portion having a low X-ray transmittance such as the abdomen.
[0040]
Next, a method for integrating the determination results of each of the reduced presence / absence determination units 101 to 103 by the determination unit 104 will be described.
The integration rule of the present embodiment employs a large number of determination results among the determination results of the respective presence / absence determination units 101 to 103 by the determination unit 104. This will be specifically described with reference to the flowchart of FIG.
First, it is determined whether or not the first squeezing presence / absence determining unit 101 determines whether or not there is a squeezing (S1101). If there is no squeezing, the determination result of the second squeezing presence / absence determining unit 102 is referred to. The process ends with no squeezing.
[0041]
If the determination result of the second squeezing presence / absence determination unit 102 is squeezed, the determination result of the third squeezing / non-squeezing determination unit 103 is referred to. If there is no squeezing, the determination result of the determination unit 104 is determined to be no squeezing. The process is terminated as there is a squeeze.
[0042]
Also, if the first squeezing presence / absence determining unit 101 determines that there is a squeezing, the determination result of the second squeezing / non-squeezing determining unit 102 is referred to. If there is a squeezing, the determination result of the determining unit 104 is determined to be squeezing and the processing is terminated. If the determination result of the second squeezing presence / absence determining unit 102 is not squeezed, the determination result of the third squeezing / non-squeezing determining unit 103 is referred to. If there is no squeezing, the determination result of the deciding unit 104 is determined to be no squeezing. The process is terminated as there is a squeeze.
[0043]
In the present embodiment, only three types of squeezing presence / absence determination units are used, but the number may be expanded to a larger number. In addition, an algorithm for determining the presence or absence of irradiation reduction other than that used in the present embodiment may be used.
[0044]
As described above, in the present embodiment, the results of a plurality of the presence / absence determination units are integrated, which has the effect of improving the determination accuracy. Further, since the final determination is made according to a large number of determinations among a plurality of determination results on the presence / absence of squeezing, there is an effect that accuracy is improved as compared with the case where only one squeezing / non-squeezing determination unit is used.
[0045]
Next, a method for integrating the results of the respective presence / absence determining units 101 to 103 according to the second embodiment will be described with reference to the flowchart of FIG.
In the present embodiment, if the result of the first squeezing / non-squeezing determining unit 101 is completely non-squeezed, the determination result of the squeezing determining unit 104 is determined to be non-squeezed and the process is terminated.
[0046]
On the other hand, if the result of the first squeezing presence / absence determining unit 101 is not completely squeezed, the process proceeds to step 1202 (S1201). Next, in step S1202, if the result of the first squeezing presence / absence determination bar 101 is completely reduced, the determination result of the determination unit 104 is determined to be squeezed, and the process ends. Otherwise, the process proceeds to step S1203. In step S1203, it is determined whether or not the result of the first squeezing presence / absence determination unit 101 is high in the possibility of no squeezing. If the possibility of no squeezing is high, the process proceeds to step S1204. Otherwise, the process proceeds to step S1206.
[0047]
If the determination result of the second squeezing presence / absence determining unit 102 is that there is no squeezing, the determination result of the deciding unit 104 is determined to be squeezed, and otherwise, the process ends (S1204). In step S1205, if the result of the third squeezing presence / absence determination unit 103 indicates that there is no squeezing, the result of the determination unit 104 is determined to be squeezed, and if there is a squeeze, the result of the determination unit 104 is determined to be squeezed and the processing is terminated.
Note that the same processing as that in FIG. 12 may be performed by permutating the algorithms of the determination units 101 to 103 for the presence or absence of squeezing.
[0048]
According to the present embodiment, when a highly reliable determination is made with respect to the determination of the presence / absence of squeezing as a result of each squeezing / non-presence determining unit, there is an effect that the determination accuracy is further improved by adopting the determination result.
In addition, when the certainty of determination by each of the presence / absence determination units is low, the determination result occupying a large number of the determination results of the respective determination / non-existence determination units is adopted, so that the determination accuracy is further improved.
[0049]
Next, a method of integrating the results of the respective presence / absence determining units 101 to 103 according to the third embodiment will be described with reference to FIG.
In the present embodiment, when the determination result of one determination unit among the respective reduction presence / absence determination units determines that there is a complete reduction, the determination result of the determination unit 104 is determined to be the reduction, and the process is terminated.
If none of the determination results of each of the squeezed presence / absence determining units is completely squeezed, the same processing as in the first embodiment shown in FIG. 11 is performed.
[0050]
According to the present embodiment, if there is a certain determination result among the determination results of the presence or absence of the squeezing, the determination result is adopted, so that the determination accuracy is improved. Furthermore, when there is no reliable determination result among the determination results of the presence or absence of each squeezing, there is an effect that the determination accuracy is improved by performing the same processing as in the first embodiment.
[0051]
Next, a method of integrating the results of the respective presence / absence determining units 101 to 103 according to the fourth embodiment will be described with reference to FIG.
In the present embodiment, when the determination result of one determination unit of each of the presence / absence determination units determines that there is no squeeze, the determination result of the determination unit 104 is determined to be no squeeze, and the process ends.
If none of the determination results of the determination units for the presence / absence of squeezing is completely squeezed, processing similar to that in the first embodiment shown in FIG. 11 is performed.
[0052]
According to the present embodiment, if there is a certain determination result among the determination results of the presence or absence of the squeezing, the determination result is adopted, so that the determination accuracy is improved. Furthermore, when there is no reliable determination result among the determination results of the presence or absence of each squeezing, there is an effect that the determination accuracy is improved by performing the same processing as in the first embodiment.
[0053]
Next, a fifth embodiment will be described.
In the present embodiment, the result of each of the presence / absence determination units is digitized, and the presence / absence of the reduction is determined from the total value of the results. For example, if flg11 is 1, the determination value h1 = 2, if flg11 is 2, the determination value h1 = 1, if flg11 is 3, the determination value h1 = -1, and if flg11 is 4, the determination value h1 = -2. Similarly, if flg21 is 1, decision value h2 = 2, if flg21 is 2, decision value h2 = 1, if flg21 is 3, decision value h2 = -1, and if flg21 is 4, decision value h2 = -2. .
[0054]
Similarly, if flg31 is 1, decision value h3 = 2, if flg31 is 2, decision value h3 = 1, if flg31 is 3, decision value h3 = -1 and if flg31 is 4, decision value h3 = -2. . And the determination part 104 determines the presence or absence of squeezing from the total value of h1 + h2 + h3. For example, when the total value is 0 or more, it is determined that there is no squeezing, and when it is lower than 0, it is determined that there is squeezing.
In the present embodiment, the number of squeezing presence / absence determining units may be increased. Further, the digitization of the determination may be changed.
[0055]
According to the present embodiment, the result of the determination unit for the presence or absence of each squeezing can be digitized and comprehensively determined, so that the determination accuracy is improved.
[0056]
Next, a sixth embodiment will be described.
Appearance frequency calculated by the appearance frequency calculation unit 402 of the first squeezing presence / absence determination unit 101, dispersion value of the irradiation end point calculated by the second determination unit 705 of the second squeezing presence / absence determination unit 102, and third squeezing The total value of | x1−xa | and | x2−x1 | calculated by the third determination means 904 of the presence / absence determination unit 103 is used as an explanatory variable, and multiple regression analysis is performed using the presence / absence of squeezing as a target variable to create a line format To do. For example, the objective variable is 1 if there is a threshold, and 0 if there is no objective variable. If an unknown image is input, the explanatory variable is calculated to obtain the value of the line format. For example, if the value of the line format is 0.5 or more, there is a reduction. If it is less than 5 mm, there is no squeezing.
[0057]
Although a linear regression equation is used here, a neural network, an agent, or the like may be used.
Further, the squeezing presence / absence determining unit is not limited to three.
[0058]
According to the present embodiment, it is possible to statistically reflect the result of each of the squeezing presence / absence determination portions in the determination result, and there is an effect that the determination accuracy is further improved. In addition, when a neural network is used to create a function, it is possible to reflect a non-linear statistical distribution, which has the effect of increasing the determination accuracy.
[0059]
Next, the storage medium according to the present invention will be described.
When the system composed of the blocks shown in FIGS. 1, 4, 7, and 9 is constituted by a computer system including a memory such as a CPU and a ROM, the memory constitutes a storage medium according to the present invention. This storage medium stores a program for executing the processing procedure for controlling the operation described above with reference to the flowcharts of FIGS. 5, 6, 8, 10, and 11.
[0060]
As the storage medium, a semiconductor memory such as ROM or RAM, an optical disk, a magneto-optical disk, a magnetic medium, or the like may be used. These may be a CD-ROM, a floppy disk, a magnetic medium, a magnetic card, a nonvolatile memory card, or the like. It may be configured and used.
[0061]
Therefore, the storage medium is used in other systems and apparatuses other than the systems and apparatuses shown in the above drawings, and the system or computer reads out and executes the program code stored in the storage medium as described above. Functions equivalent to those in each embodiment can be realized, and equivalent effects can be obtained, and the object of the present invention can be achieved.
[0062]
Also, when the OS running on the computer performs part or all of the processing, or the program code read from the storage medium is an extension function board inserted in the computer or an extension connected to the computer Even when the CPU or the like provided in the extended function board or the extended function unit performs part or all of the processing based on the instruction of the program code after being written in the memory provided in the functional unit, While equivalent functions can be realized, equivalent effects can be obtained, and the object of the present invention can be achieved.
[0063]
【The invention's effect】
As described above, according to the present invention, if there is a certain determination result among the determination results, the determination result is adopted, so that the determination accuracy is improved. In addition, if there is no reliable judgment result among the judgment results, the final judgment is made according to many judgments among the judgment results for the presence or absence of the squeezing, so the accuracy is higher than when only one squeezing judgment criterion is used. Is effective.
[0068]
Further, according to another feature of the present invention, by using the appearance frequency of the density determined from the MAX value of the entire image as a determination criterion, there is an effect that a stable determination can be performed even when an imaging target is applied to the irradiation end. . In addition, there is an effect that the determination can be performed stably even when the radiation dose is small or when the imaging target covers the entire image edge without being affected by the intensity of the radiation dose.
[0069]
In addition, by using the variance of the coordinate values of a plurality of irradiation end points as a determination criterion, there is an effect that the presence / absence of irradiation squeezing can be well extracted based on that value. Further, by using the secondary difference value, it is possible to accurately determine a boundary point between an area directly irradiated with X-rays and an area not irradiated with X-rays even for an object with low X-ray transmittance. Therefore, even if a portion having a low X-ray transmittance, such as the abdomen, covers the edge of the image, it is possible to accurately extract the presence of irradiation.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a configuration diagram showing an X-ray image of a hand imaged without squeezing irradiation;
FIG. 3 is a configuration diagram showing an X-ray image of a hand and an irradiation end A taken with irradiation squeezing.
FIG. 4 is a block diagram illustrating a configuration of a first squeezing presence / absence determining unit.
FIG. 5 is a flowchart showing a flow of processing of a first squeezing presence / absence determining unit.
FIG. 6 is a configuration diagram showing a determination area of a second squeezing presence / absence determination unit;
FIG. 7 is a block diagram showing a configuration of a second squeezing presence / absence determining unit.
FIG. 8 is a flowchart showing a flow of processing of a second squeezing presence / absence determining unit.
FIG. 9 is a block diagram showing a configuration of a third squeezing presence / absence determining unit.
FIG. 10 is a flowchart showing a flow of processing of a third squeezing presence / absence determining unit.
FIG. 11 is a flowchart illustrating a processing flow according to the first embodiment;
FIG. 12 is a flowchart illustrating a processing flow according to the second embodiment;
FIG. 13 is a flowchart illustrating a processing flow according to the third embodiment;
FIG. 14 is a flowchart illustrating a process flow according to the fourth embodiment;
[Explanation of symbols]
101 First squeezing presence / absence determination unit
102 Second squeezing presence / absence determination unit
103 Third squeezing presence / absence determination unit
104 judgment part
401 First characteristic value calculation means
402 First appearance frequency calculation means
403 first determination means
701 Coordinate instruction means
702 Characteristic value extraction means
703 Endpoint extraction means
704 Memory means
705 Second determination means
901 Secondary difference value calculation means
902 Left end point extraction means
903 Right end point extraction means
904 Third determination means

Claims (7)

At least two squeezed presence / absence judging means each having different judgment criteria for the presence or absence of radiation squeezing with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is a squeezing, it is determined that there is an aperture, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means Integrated determination means for determining the presence or absence of an aperture based on the determination result of the determination means;
An irradiation squeezing presence / absence judging device comprising: At least two squeezed presence / absence judging means each having different judgment criteria for the presence or absence of radiation squeezing with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is no squeezing, it is determined that there is no squeezing, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means. Integrated determination means for determining the presence or absence of an aperture based on the determination result of the determination means;
An irradiation squeezing presence / absence judging device comprising:   The determination criterion of each of the squeezing presence / absence determining means uses at least one of a density appearance frequency determined from a MAX value of the density of the entire image, a variance of coordinate values of a plurality of irradiation end points, and a secondary difference value. The irradiation squeezing presence / absence judging device according to claim 1 or 2. A squeezing presence / absence determination step of determining the presence / absence of squeezing by at least two squeezing / non-squeezing determination means different from each other in the determination criteria of the presence / absence of irradiation irradiation with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is a squeezing, it is determined that there is an aperture, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means An integrated determination step of determining the presence or absence of an aperture based on the determination result of the determination means;
A method for determining the presence or absence of irradiation squeezing. A squeezing presence / absence determination step of determining the presence / absence of squeezing by at least two squeezing / non-squeezing determination means different from each other in the determination criteria of the presence / absence of irradiation irradiation with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is no squeezing, it is determined that there is no squeezing, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means. An integrated determination step of determining the presence or absence of an aperture based on the determination result of the determination means;
A method for determining the presence or absence of irradiation squeezing. A squeezing presence / absence determination step of determining the presence / absence of squeezing by at least two squeezing / non-squeezing determination means different from each other in the determination criteria of the presence / absence of irradiation irradiation with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is a squeezing, it is determined that there is an aperture, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means An integrated determination step of determining the presence or absence of an aperture based on the determination result of the determination means;
A computer-readable storage medium storing a program for causing a computer to execute the program. A squeezing presence / absence determination step of determining the presence / absence of squeezing by at least two squeezing / non-squeezing determination means different from each other in the determination criteria of the presence / absence of irradiation irradiation with respect to the radiographic image;
Of the plurality of squeezing presence / absence determining means, when the first squeezing presence / absence determining means determines that there is no squeezing, it is determined that there is no squeezing, and in other cases, the squeezing presence / absence different from the first squeezing presence / absence determining means. An integrated determination step of determining the presence or absence of an aperture based on the determination result of the determination means;
A computer-readable storage medium storing a program for causing a computer to execute the program.

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