JPH057579A - Irradiation area extractor for radiation image - Google Patents
Irradiation area extractor for radiation imageInfo
- Publication number
- JPH057579A JPH057579A JP3145775A JP14577591A JPH057579A JP H057579 A JPH057579 A JP H057579A JP 3145775 A JP3145775 A JP 3145775A JP 14577591 A JP14577591 A JP 14577591A JP H057579 A JPH057579 A JP H057579A
- Authority
- JP
- Japan
- Prior art keywords
- irradiation field
- contour
- area
- image
- small
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005855 radiation Effects 0.000 title claims abstract description 68
- 239000006185 dispersion Substances 0.000 claims abstract description 15
- 238000000605 extraction Methods 0.000 claims description 19
- 230000005540 biological transmission Effects 0.000 claims description 14
- 239000000284 extract Substances 0.000 claims description 3
- 238000009966 trimming Methods 0.000 abstract 1
- 238000000034 method Methods 0.000 description 16
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 13
- 210000004072 lung Anatomy 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 9
- 230000001186 cumulative effect Effects 0.000 description 4
- 238000002601 radiography Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 2
- 239000012780 transparent material Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Image Analysis (AREA)
- Radiography Using Non-Light Waves (AREA)
- Apparatus For Radiation Diagnosis (AREA)
- Image Processing (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は放射線画像の照射野領域
抽出装置に関し、詳しくは、照射野絞りを行って撮影さ
れた放射線画像から照射野の領域部分のみを抽出する装
置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image irradiation field region extracting apparatus, and more particularly to a device for extracting only a region portion of the irradiation field from a radiation image photographed by narrowing the irradiation field.
【０００２】[0002]
【従来の技術】Ｘ線画像のような放射線画像は、病気診
断用などに多く用いられており、このＸ線画像を得るた
めに、被写体を透過したＸ線を蛍光体層（蛍光スクリー
ン）に照射し、これにより可視光を生じさせてこの可視
光を通常の写真と同様に銀塩を使用したフィルムに照射
して現像した、所謂、放射線写真が従来から多く利用さ
れている。2. Description of the Related Art Radiation images such as X-ray images are often used for diagnosing diseases, etc. In order to obtain this X-ray image, X-rays transmitted through a subject are applied to a phosphor layer (fluorescent screen). Conventionally, so-called radiography, in which visible light is generated by irradiation, and the visible light is applied to a film using a silver salt to develop the film, which is the same as in ordinary photography, has been conventionally used.
【０００３】しかし、近年、銀塩を塗布したフィルムを
使用しないで、蛍光体層から直接画像を取り出す方法が
工夫されるようになってきている。この方法としては、
被写体を透過した放射線を蛍光体に吸収せしめ、しかる
後、この蛍光体を例えば光又は熱エネルギーで励起する
ことによりこの蛍光体が上記吸収により蓄積している放
射線エネルギーを蛍光として放射せしめ、この蛍光を光
電変換して画像信号を得る方法がある。このようにして
得られた放射線画像信号は、そのままの状態で、或いは
画像処理を施されてプリンタ，ＣＲＴ等に出力されて可
視化されるが、コンピュータによる画像処理のためにデ
ジタル化されることが多い。However, in recent years, a method for directly taking out an image from a phosphor layer has been devised without using a film coated with a silver salt. For this method,
Radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy to cause the phosphor to emit the radiation energy accumulated by the absorption as fluorescence. There is a method of obtaining an image signal by performing photoelectric conversion on the. The radiation image signal obtained in this way is visualized as it is or after being subjected to image processing and output to a printer, CRT or the like, but it may be digitized for image processing by a computer. Many.
【０００４】[0004]
【発明が解決しようとする課題】ところで、放射線撮影
においては、放射線の被照射部分をなるべく少なくしよ
うとする人道的な理由や、診断に関係ない部分からの散
乱線を防ぐといった診断上の理由から、被写体の一部や
放射線源に鉛板等の放射線非透過物を設置して、被写体
に対する放射線の照射野を限定する照射野絞りが行われ
る場合がある。By the way, in radiography, there are humanitarian reasons to reduce the radiation-exposed portion as much as possible and diagnostic reasons such as preventing scattered radiation from a portion unrelated to the diagnosis. In some cases, a radiation non-transparent material such as a lead plate is installed on a part of the subject or a radiation source to perform an irradiation field stop that limits the irradiation field of the radiation to the subject.
【０００５】一方、前記ディジタル放射線画像の画像処
理（階調処理，空間周波数処理等）においては、画像デ
ータの統計的性質（データの最大値・最小値・ヒストグ
ラム）から処理条件を決定し、関心領域を見やすく仕上
げる画像処理を施すようにしているが、前述のように照
射野絞りが行われる場合には、画像データの統計的性質
に前記照射野絞りの部分（放射線が直接照射されなかっ
た部分）のデータが影響し、全体的に放射線透過量の少
ない方に偏った性質を示すことになってしまい、画像処
理条件を適切に設定できなくなるという問題がある。On the other hand, in the image processing (gradation processing, spatial frequency processing, etc.) of the digital radiation image, the processing condition is determined from the statistical properties of the image data (maximum value / minimum value of data / histogram), Although the image processing is performed to finish the area so that it is easy to see, when the irradiation field is narrowed as described above, the statistical property of the image data indicates the portion of the irradiation field (the portion where radiation was not directly irradiated). The data of 1) influences and shows the property that the radiation transmission amount is generally small, and there is a problem that the image processing conditions cannot be set appropriately.
【０００６】例えば、図９に示すように、胸部放射線画
像における関心領域である肺野領域を、縦方向及び横方
向のプロジェクションにおける極大・極小値を用いて認
識させ、かかる肺野領域内の画像データのヒストグラム
或いは累積ヒストグラムに基づいて階調処理条件を決定
することが行われているが、図10に示すように、画像下
部に照射野絞りされた部分が入ると、プロジェクション
が前記絞り部分を含めて作成されるから、正しく肺野領
域を認識させることができなくなり、照射野絞りの部分
を含んで肺野領域が認識されることになる。従って、図
10に示すような場合には、誤認識された肺野領域内にお
ける画像データのヒストグラム或いは累積ヒストグラム
を用いて階調処理条件を設定すると、全体的に低めの画
像データに合わせた階調処理が行われることになり、処
理後の画像が白っぽく微妙なコントラストが出ない画像
となってしまう。For example, as shown in FIG. 9, a lung field region, which is a region of interest in a chest radiographic image, is recognized by using the maximum and minimum values in the vertical and horizontal projections, and the image in the lung field region is recognized. It has been performed to determine the gradation processing condition based on the histogram of data or the cumulative histogram, but as shown in FIG. 10, when a part where the irradiation field is narrowed down enters the lower part of the image, the projection covers the narrowed part. Since it is created by including it, the lung field region cannot be correctly recognized, and the lung field region is recognized including the irradiation field stop portion. Therefore, the figure
In the case as shown in 10, if the gradation processing condition is set using the histogram or the cumulative histogram of the image data in the erroneously recognized lung field region, the gradation processing matched to the lower image data as a whole will be performed. As a result, the processed image becomes a whitish image with no delicate contrast.
【０００７】そこで、画像処理条件を決定させるに当た
って、予め画像内の照射野の部分のみを抽出し、該照射
野内の画像データのみに基づいて関心領域検出や条件設
定を行わせる必要があり、照射野を抽出する方法として
は従来以下のような種々の方法が提案されている。例え
ば特開平１−２６７６３４号公報には、画像全体のヒス
トグラムを作成し、照射野部分の山と照射野絞りの部分
の山との分離度が最も良くなる値で画像データの２値化
を行って照射野部分を抽出する方法が開示されている。
また、特開平２−８１２７８号公報には、画像を格子状
に複数の小ブロックに分割し、各小ブロック内で各種の
高周波抽出処理を行い、高周波成分を多く含む部分を照
射野絞り領域として認識する方法が開示されている。更
に、特開昭６３−１８３４３４号公報には、画像データ
のプロファイル情報の微分処理を行い、照射野領域の輪
郭部分を検出する方法が開示されている。Therefore, in determining the image processing condition, it is necessary to extract only the irradiation field portion in the image in advance, and to perform the region of interest detection and condition setting based on only the image data in the irradiation field. The following various methods have been proposed as methods for extracting fields. For example, in Japanese Unexamined Patent Publication No. 1-267634, a histogram of the entire image is created, and the image data is binarized with a value that maximizes the degree of separation between the peak in the irradiation field portion and the peak in the irradiation field stop portion. There is disclosed a method of extracting an irradiation field portion by using the above method.
Further, in Japanese Patent Application Laid-Open No. 2-81278, an image is divided into a plurality of small blocks in a grid pattern, various high frequency extraction processing is performed in each small block, and a portion containing a large amount of high frequency components is used as an irradiation field stop region. A method of recognition is disclosed. Further, Japanese Patent Laid-Open No. 63-183434 discloses a method of differentiating profile information of image data to detect the contour portion of the irradiation field area.
【０００８】しかしながら、上記の２値化による方法の
場合には、照射野絞りの部分の濃度値と照射野内の人体
低濃度域とが重なることが多いため、単純な２値化を行
っても照射野の領域のみを精度良く抽出することは困難
である。また、小ブロック毎の高周波抽出による方法の
場合には、照射野絞りの領域がノイジーであって細かい
濃度変化が多いことを利用するものであるから、超微細
な変化を捉えるために少なくとも2000×2000画素程度の
画像を用いて高精度の解析を行う必要があり、実時間処
理が要求される自動画像処理では実現的とは言えない。
更に、プロファイル情報の微分値に基づいて輪郭を検出
する方法の場合には、各ライン（カラム）毎に照射野領
域の輪郭候補点を求めた後、それらを結んで輪郭線を得
る処理を行うが、１画素単位で見ていく作業ではノイズ
に影響されて不正確な連結を行うことも多く、方程式に
よる直線近似を行うにしても信頼性が低いという問題が
ある。However, in the case of the above-described binarization method, the density value in the irradiation field diaphragm often overlaps with the low-concentration region of the human body in the irradiation field, so that even simple binarization is performed. It is difficult to accurately extract only the area of the irradiation field. Also, in the case of the method by high-frequency extraction for each small block, the fact that the area of the irradiation field diaphragm is noisy and there are many minute density changes is used, so at least 2000 × in order to capture ultrafine changes. It is necessary to perform highly accurate analysis using an image of about 2000 pixels, which is not feasible with automatic image processing that requires real-time processing.
Further, in the case of the method of detecting the contour based on the differential value of the profile information, after the contour candidate points of the irradiation field region are obtained for each line (column), the processing of connecting them to obtain the contour line is performed. However, in the work of observing on a pixel-by-pixel basis, inaccurate connection is often performed due to the influence of noise, and there is a problem that reliability is low even if linear approximation by an equation is performed.
【０００９】本発明は上記問題点に鑑みなされたもので
あり、照射野領域の抽出が比較的簡便な処理によって精
度良く行える放射線画像の照射野領域抽出装置を提供す
ることを目的とする。The present invention has been made in view of the above problems, and an object of the present invention is to provide a radiation image irradiation field region extraction apparatus capable of accurately extracting the irradiation field region by a relatively simple process.
【００１０】[0010]
【課題を解決するための手段】そのため本発明にかかる
放射線画像の照射野領域抽出装置は、照射野絞りを行っ
て被写体に照射された放射線の被写体各部の透過量に対
応して形成される放射線画像の照射野領域抽出装置であ
って、図１に示すように構成される。図１において、小
領域分割手段は、放射線画像の画像領域を縦横に複数の
小領域に分割し、分散値算出手段は、前記分割された小
領域毎に、小領域内に含まれる画像データの分散値を算
出する。Therefore, a radiation image irradiation field region extraction apparatus according to the present invention performs radiation field narrowing and forms radiation corresponding to the amount of transmission of each portion of the radiation irradiated to the object. An irradiation field area extraction device for an image, which is configured as shown in FIG. In FIG. 1, the small area dividing means divides the image area of the radiation image into a plurality of small areas in the vertical and horizontal directions, and the dispersion value calculating means divides the image data contained in the small area for each of the divided small areas. Calculate the variance.
【００１１】そして、輪郭認識手段は、分散値が所定値
以上である小領域を所定数以上含む小領域の縦横列を照
射野の輪郭として認識し、照射野領域抽出手段は、輪郭
として認識された小領域列よりも内側の画像領域を照射
野領域として抽出する。ここで、前記分散値算出手段で
分散値を算出する小領域内の画像データを、オリジナル
の画像データを間引いた画像データとすることが好まし
い。The contour recognizing means recognizes the vertical and horizontal rows of the small areas including the predetermined number or more of the small areas having the variance value of the predetermined value or more as the contours of the irradiation field, and the irradiation field area extracting means recognizes the contours as the contours. The image area inside the small area sequence is extracted as the irradiation field area. Here, it is preferable that the image data in the small area for which the variance value is calculated by the variance value calculation unit is image data obtained by thinning out the original image data.
【００１２】また、輪郭認識手段における照射野の輪郭
認識を、輪郭相当の小領域内若しくは前記輪郭相当の小
領域の近傍の小領域内における画像データの代表値に基
づいて正誤判定し、誤りであると判定されたときに前記
輪郭相当の小領域に基づく最終的な照射野の輪郭認識を
禁止する正誤判定手段を設けて構成すると良い。また、
輪郭認識手段によって画像の内外方向で複数の輪郭が認
識されたときに、前記照射野領域抽出手段による照射野
領域の抽出を最も外側の輪郭に基づいて行わせる外側輪
郭選択手段を設けて構成しても良い。Further, the contour recognition of the irradiation field by the contour recognition means is determined as correct or incorrect based on the representative value of the image data in the small area corresponding to the contour or in the small area near the small area corresponding to the contour, and an error is detected. It is preferable to provide a correctness determination means for prohibiting the final contour recognition of the irradiation field based on the small area corresponding to the contour when it is determined that there is. Also,
When a plurality of contours are recognized in the inner and outer directions of the image by the contour recognizing means, an outer contour selecting means is provided for causing the irradiation field area extracting means to extract the irradiation field area based on the outermost contour. May be.
【００１３】[0013]
【作用】放射線画像の画像領域を縦横に複数の小領域に
分割したときに、照射野絞りによって放射線の照射が遮
られたところに相当する小領域では、放射線の透過量が
略一様に低いから、画像データは低透過量側に大きく偏
って分散値は低くなる。また、照射野に相当する小領域
では、いろいろな構造物が存在し、放射線透過量にばら
つきがあるために比較的分散値は高くなる。これに対
し、照射野絞りの境界線を含む小領域では、照射野絞り
が行われた最も低い透過量の部分と照射野内の比較的高
い透過量の部分との両方を含むことになって、画像デー
タは最も高い分散値を示すことになる。When the image area of the radiation image is vertically and horizontally divided into a plurality of small areas, the radiation transmission amount is substantially uniform in the small areas corresponding to the areas where the irradiation of the radiation is blocked by the irradiation field diaphragm. Therefore, the image data is largely biased toward the low transmission amount side and the dispersion value is low. Further, in a small region corresponding to the irradiation field, various structures are present, and the radiation transmission amount varies, so that the dispersion value becomes relatively high. On the other hand, in the small area including the boundary line of the irradiation field stop, both the part of the lowest transmission amount where the irradiation field stop was performed and the part of relatively high transmission amount in the irradiation field are included, The image data will have the highest variance.
【００１４】従って、分散値が最も高い小領域は、照射
野絞りが行われた部分（放射線が遮られた部分）と照射
野の部分との両方を含むものと予測され、このような小
領域が複数存在する小領域の列は、そのまま照射野の輪
郭を示すものとして認識することができる。上記のよう
に、小領域毎の画像データのばらつきを判断して、照射
野を決定する輪郭を求めるものであるから、間引いた画
像データを用いても輪郭認識の精度が大きく低下するも
のではないから、間引きデータを用いて処理を簡便化さ
せると良い。Therefore, the small area having the highest dispersion value is predicted to include both the area where the irradiation field is narrowed (the area where radiation is blocked) and the area of the irradiation field. A row of small areas in which a plurality of symbols are present can be recognized as they are, which indicate the contour of the irradiation field. As described above, since the contour that determines the irradiation field is determined by determining the variation in the image data for each small area, the accuracy of contour recognition does not greatly deteriorate even if the thinned image data is used. Therefore, it is preferable to simplify the processing by using the thinned data.
【００１５】前述のように分散値が高い小領域が複数含
まれる列を照射野の輪郭として認識するときに、照射野
内で透過量のばらつきにより分散値が比較的高いところ
（例えば被写体構造物の輪郭又は被写体の輪郭）や、照
射野絞り部分でノイズ等の影響によって分散値が高くな
るところが存在すると、この部分を照射野領域の輪郭と
して誤認識する惧れがある。As described above, when a row including a plurality of small areas having a high dispersion value is recognized as the contour of the irradiation field, the dispersion value is relatively high in the irradiation field due to the variation of the transmission amount (for example, the object structure If there is a portion where the variance value is high due to the influence of noise or the like on the contour or the contour of the subject) or the irradiation field stop portion, this portion may be erroneously recognized as the contour of the irradiation field area.
【００１６】ここで、正確に照射野の輪郭が認識された
場合には、照射野輪郭に相当する小領域よりも外側は照
射野絞りの部分であり、また、照射野輪郭に相当する小
領域には照射野絞りの部分を少なくとも含み、更に、照
射野輪郭に相当する小領域よりも内側には照射野絞り部
分を含まないはずである。従って、最終的に分散値に基
づいて照射野の輪郭に相当する小領域を判別する前に、
輪郭相当の小領域内若しくは前記輪郭相当の小領域の近
傍の小領域内における画像データの代表値が、前記の真
の輪郭認識がなされた場合の特性に合致しているか否か
を判定させれば、照射野の輪郭が誤認識されることを回
避できる。Here, when the contour of the irradiation field is accurately recognized, the area outside the small area corresponding to the irradiation field contour is the irradiation field stop portion, and the small area corresponding to the irradiation field contour. Should include at least the irradiation field stop portion, and should not include the irradiation field stop portion inside the small area corresponding to the irradiation field contour. Therefore, before finally determining the small area corresponding to the contour of the irradiation field based on the variance value,
It is possible to determine whether the representative value of the image data in the small area corresponding to the contour or in the small area near the small area corresponding to the contour matches the characteristics when the true contour recognition is performed. For example, it is possible to avoid erroneously recognizing the contour of the irradiation field.
【００１７】また、輪郭の誤認識は、照射野内での放射
線透過量のばらつきによって専ら生じるものと予測され
るから、複数の輪郭が認識された場合には、最も外側の
輪郭が正しいと判断する。Further, it is predicted that the erroneous recognition of the contour will occur exclusively due to the variation of the radiation transmission amount in the irradiation field. Therefore, when a plurality of contours are recognized, the outermost contour is judged to be correct. .
【００１８】[0018]
【実施例】以下に本発明の実施例を説明する。一実施例
を示す図２は、本発明にかかる放射線画像の照射野領域
抽出装置を含む医療用の放射線画像記録読取装置であっ
て、医療用として人体の胸部正面の放射線撮影に適用し
たものである。EXAMPLES Examples of the present invention will be described below. FIG. 2 showing an embodiment is a medical radiation image recording / reading device including a radiation image irradiation field region extracting device according to the present invention, which is applied to radiation imaging of the front of the chest of a human body for medical purposes. is there.
【００１９】ここで、放射線発生源１は、放射線制御装
置２によって制御されて、人体胸部Ｍ（被写体）に向け
て放射線（一般的にはＸ線）を照射するが、本実施例に
おいては、放射線発生源１と人体胸部Ｍとの間に、鉛板
などの放射線非透過物によって形成された遮蔽板20が設
けられており、該遮蔽板20の開口部のみを放射線の照射
野とする照射野絞りを行って放射線撮影が行われるよう
にしてある。Here, the radiation source 1 is controlled by the radiation control device 2 to irradiate the human chest M (subject) with radiation (generally an X-ray), but in this embodiment, Between the radiation source 1 and the human chest M, a shielding plate 20 formed of a non-radiation transparent material such as a lead plate is provided, and irradiation is performed by using only the opening of the shielding plate 20 as a radiation irradiation field. A radiography is performed by narrowing the field.
【００２０】記録読取装置３は、胸部Ｍを挟んで放射線
源１と対向する面に放射線画像変換パネル４を備えてお
り、この変換パネル４は放射線源１からの照射放射線量
に対する胸部Ｍの放射線透過率分布に従ったエネルギー
を輝尽性蛍光体層に蓄積し、そこに胸部Ｍの潜像を形成
する。前記変換パネル４は、支持体上に輝尽性蛍光体層
を、輝尽性蛍光体の気相堆積、或いは輝尽性蛍光体塗料
塗布によって設けてあり、該輝尽性蛍光体層は環境によ
る悪影響及び損傷を遮断するために、保護部材によって
遮蔽若しくは被覆されている。尚、前記輝尽性蛍光体材
料としては、例えば、特開昭６１−７２０９１号公報、
或いは、特開昭５９−７５２００号公報に開示されるよ
うな材料が使われる。The recording / reading device 3 is provided with a radiation image conversion panel 4 on the surface facing the radiation source 1 with the chest M sandwiched therebetween, and the conversion panel 4 is the radiation of the chest M with respect to the radiation dose from the radiation source 1. Energy according to the transmittance distribution is accumulated in the stimulable phosphor layer, and a latent image of the chest M is formed there. The conversion panel 4 is provided with a stimulable phosphor layer on a support by vapor deposition of the stimulable phosphor or coating of a stimulable phosphor coating, and the stimulable phosphor layer is an environment. It is shielded or covered by a protective member in order to block the adverse effects and damages caused by. Examples of the stimulable phosphor material include, for example, JP-A-61-72091,
Alternatively, a material as disclosed in JP-A-59-75200 is used.
【００２１】光ビーム発生部（ガスレーザ，固体レー
ザ，半導体レーザ等）５は、出射強度が制御された光ビ
ームを発生し、その光ビームは種々の光学系を経由して
走査器６に到達し、そこで偏向を受け、更に、反射鏡７
で光路を偏向させて、変換パネル４に輝尽励起走査光と
して導かれる。集光体８は、輝尽励起光が走査される変
換パネル４に近接して光ファイバからなる集光端が位置
され、上記光ビームで走査された変換パネル４からの潜
像エネルギーに比例した発光強度の輝尽発光を受光す
る。９は、集光体８から導入された光から輝尽発光波長
領域の光のみを通過させるフィルタであり、該フィルタ
９を通過した光は、フォトマル10に入射して、その入射
光に対応した電流信号に光電変換される。The light beam generator (gas laser, solid-state laser, semiconductor laser, etc.) 5 generates a light beam whose emission intensity is controlled, and the light beam reaches the scanner 6 via various optical systems. , Where it is deflected, and the reflector 7
The optical path is deflected by and is guided to the conversion panel 4 as stimulated excitation scanning light. The condensing body 8 has a condensing end made of an optical fiber located in the vicinity of the conversion panel 4 scanned by the stimulated excitation light, and is proportional to the latent image energy from the conversion panel 4 scanned by the light beam. The stimulated emission of the emission intensity is received. Reference numeral 9 is a filter that allows only light in the stimulated emission wavelength range from the light introduced from the light collector 8 to pass through. The light that has passed through the filter 9 is incident on the photomultiplier 10 and corresponds to the incident light. Is photoelectrically converted into a generated current signal.
【００２２】フォトマル10からの出力電流は、電流／電
圧変換器11で電圧信号に変換され、増幅器12で増幅され
た後、Ａ／Ｄ変換器13でデジタルデータ（放射線透過量
に比例するデジタル放射線画像信号）に変換される。そ
して、この被写体各部の放射線透過量に比例するデジタ
ル画像信号は、画像処理装置14において順次画像処理さ
れて、画像処理後の画像信号がインターフェイス16を介
してプリンタ17に伝送されるようになっている。The output current from the photomultiplier 10 is converted into a voltage signal by the current / voltage converter 11, amplified by the amplifier 12, and then digital data (digital proportional to the amount of radiation transmission) by the A / D converter 13. Radiation image signal). The digital image signal proportional to the radiation transmission amount of each part of the subject is sequentially subjected to image processing in the image processing device 14, and the image signal after the image processing is transmitted to the printer 17 via the interface 16. There is.
【００２３】15は画像処理装置14における画像処理を制
御するＣＰＵであり、Ａ／Ｄ変換器13から出力されるデ
ジタルの放射線画像データに対して階調処理を含む種々
の画像処理（例えば空間周波数処理，拡大，縮小，移
動，回転，統計処理等）を画像処理装置14において施さ
せ、診断に適した形としてからプリンタ17に出力させ、
プリンタ17で胸部放射線画像のハードコピーが得られる
ようにする。Reference numeral 15 denotes a CPU for controlling image processing in the image processing apparatus 14, which performs various image processing including gradation processing on digital radiation image data output from the A / D converter 13 (for example, spatial frequency). Processing, enlargement, reduction, movement, rotation, statistical processing, etc.) in the image processing device 14 to make it suitable for diagnosis and then output to the printer 17,
Make a hard copy of the chest radiograph available at the printer 17.
【００２４】尚、インタフェイス16を介して接続される
のは、ＣＲＴ等のモニタであっても良く、更に、半導体
記憶装置などの記憶装置（ファイリングシステム）であ
っても良い。18は読取ゲイン調整回路であり、この読取
ゲイン調整回路18により光ビーム発生部５の光ビーム強
度調整、フォトマル用高圧電源19の電源電圧調整による
フォトマル10のゲイン調整、電流／電圧変換器11と増幅
器12のゲイン調整、及びＡ／Ｄ変換器13の入力ダイナミ
ックレンジの調整が行われ、放射線画像信号の読取ゲイ
ンが総合的に調整される。It should be noted that what is connected via the interface 16 may be a monitor such as a CRT, and further a storage device (filing system) such as a semiconductor storage device. Reference numeral 18 denotes a read gain adjusting circuit. The read gain adjusting circuit 18 adjusts the light beam intensity of the light beam generator 5, the gain of the Photomul 10 by adjusting the power supply voltage of the Photomulch high-voltage power supply 19, and the current / voltage converter. The gains of the amplifier 11 and the amplifier 12 are adjusted, and the input dynamic range of the A / D converter 13 is adjusted, so that the read gain of the radiation image signal is comprehensively adjusted.
【００２５】前記画像処理装置14では、読み取られた放
射線画像信号の画像処理を行うが、かかる画像処理にお
いては、画像内における照射野の領域を抽出し、照射野
内の画像データの統計的性質、又は、照射野内でのプロ
ファイル情報などから求めた関心領域での画像データの
統計的性質などに基づいて処理条件を決定させるため
に、画像処理装置14では、図３のフローチャートに示す
ようにして画像処理の前に照射野領域の抽出を行う。The image processing device 14 performs image processing of the read radiation image signal. In such image processing, the area of the irradiation field in the image is extracted, and the statistical properties of the image data in the irradiation field are calculated. Alternatively, in order to determine the processing condition based on the statistical properties of the image data in the region of interest obtained from the profile information in the irradiation field, the image processing device 14 performs image processing as shown in the flowchart of FIG. The irradiation field area is extracted before the processing.
【００２６】ここで、図３のフローチャートに従って、
照射野領域の抽出の様子を簡単に述べると、まず、Ｓ１
では、変換パネル４から光電的に読み取られたディジタ
ル放射線画像信号の間引き処理を行ってデータ数を減少
させ、Ｓ２では、画像領域を縦横に複数の小領域に分割
する。そして、Ｓ３では、Ｓ２で複数に分割された小領
域毎に、領域内に含まれる画像信号の分散値（画像信号
分布幅）を求め、Ｓ４では、小領域毎の分散値のデータ
から照射野領域の輪郭（照射野領域と絞り領域との境
界）を規定する小領域の行及び列（本実施例では、画像
の縦方向の区分を行、横方向の区分を列とする。）の候
補を求める。Here, according to the flow chart of FIG.
A brief description of the extraction of the irradiation field region is as follows: S1
In step S2, the number of data is reduced by thinning out the digital radiation image signal photoelectrically read from the conversion panel 4, and in step S2, the image area is divided into a plurality of small areas in the vertical and horizontal directions. Then, in S3, the variance value (image signal distribution width) of the image signal included in the region is obtained for each of the small regions divided in S2, and in S4, the irradiation field is calculated from the data of the variance value for each small region. Candidates for rows and columns (in the present embodiment, vertical divisions of an image are rows and horizontal divisions are columns) of a small area that defines the contour of the area (the boundary between the irradiation field area and the aperture area). Ask for.
【００２７】Ｓ５では、輪郭を規定する小領域の行・列
として候補に上がったものが、正しいか誤っているかの
判定を行い、照射野の輪郭ではなく、人体内構造物或い
は人体の輪郭である可能性が高いと判定されたときに
は、Ｓ４で判定された候補行・列を無効として、再度Ｓ
４へ戻り、別の行・列で輪郭の候補となるものを探させ
るようにする。一方、Ｓ５でＳ４において候補として上
げた小領域の行・列が正しいと判定されたときには、か
かる小領域の行・列によって照射野の輪郭を認識し、輪
郭を規定する小領域の行・列よりも内側の領域が照射野
領域で、輪郭に規定された小領域を含む外側の領域が照
射野絞りの領域であると見做し、照射野領域の抽出を行
う。In step S5, it is determined whether or not the candidate row / column of the small area defining the contour is correct or incorrect, and it is not the contour of the irradiation field but the contour of the human body structure or the human body. When it is determined that there is a high possibility, the candidate row / column determined in S4 is invalidated and S
Return to step 4 so that another line / column is searched for a contour candidate. On the other hand, when it is determined in S5 that the row / column of the small area selected as the candidate in S4 is correct, the contour of the irradiation field is recognized by the row / column of the small area, and the row / column of the small area that defines the contour is recognized. It is considered that the inner area is the irradiation field area and the outer area including the small area defined by the contour is the irradiation field stop area, and the irradiation field area is extracted.
【００２８】尚、本実施例では、小領域分割手段，分散
値算出手段，輪郭認識手段，照射野領域抽出手段，正誤
判定手段，外側輪郭選択手段としての機能は、ＣＰＵ1
5，画像処理装置14が備えているものとする。次に上記
に概略説明した照射野領域の抽出について詳細に説明す
る。まず、Ｓ１における間引き処理であるが、一般にデ
ィジタル放射線画像信号の原画像は、2000×2000画素程
度であるが、照射野領域の抽出処理における処理時間の
短縮のために、128 ×128 画素程度にまで信号を間引く
処理を行う。間引き方法は、図４に示すように、マトリ
クス内の１点の画素値を用いても良いし、マトリクス内
の平均値を用いても良い。In the present embodiment, the functions of the small area dividing means, the variance value calculating means, the contour recognizing means, the irradiation field area extracting means, the correctness determining means, and the outer contour selecting means are the CPU 1
5. It is assumed that the image processing device 14 is equipped. Next, the extraction of the irradiation field area outlined above will be described in detail. First, regarding the thinning-out processing in S1, the original image of the digital radiation image signal is generally about 2000 × 2000 pixels, but in order to reduce the processing time in the extraction processing of the irradiation field area, it is reduced to about 128 × 128 pixels. Signal is thinned out. As the thinning method, as shown in FIG. 4, a pixel value at one point in the matrix may be used, or an average value in the matrix may be used.
【００２９】128 ×128 画素程度にまで信号を間引く
と、次のＳ２では、４×４画素程度の小領域を単位とし
て画像領域を縦横に分割する処理を行い、画像を32×32
個程度に格子状に分割する（図６参照）。Ｓ３では、間
引きデータ上での４×４画素からなる小領域毎に、含ま
れる16個画素の画像信号の分散値（信号分布幅）を算出
する。When the signals are thinned out to about 128 × 128 pixels, in the next step S2, the image area is divided vertically and horizontally in units of small areas of about 4 × 4 pixels, and the image is divided into 32 × 32 pixels.
Divide into about a grid (see FIG. 6). In S3, the variance value (signal distribution width) of the image signal of 16 pixels included in each small region of 4 × 4 pixels on the thinned-out data is calculated.
【００３０】ここで、小領域が画像領域内のどの部分に
相当するかによって、小領域内における濃度分布（信号
分布）が図５（Ａ）〜（Ｄ）に示すような特性を示すこ
とになる。即ち、照射野内の素抜けの部分に相当する図
５（Ａ）に示すような小領域においては、小領域内に高
濃度画素（高い信号値）が一様に分布しているために分
散値は低くなる。また、小領域が照射野絞りの部分に相
当する場合には、図５（Ｂ）に示すように小領域内に低
濃度画素（低い信号値）が一様に分布しているために、
この場合も分散値は低くなる。一方、小領域が人体部分
に重なっている場合には、いろいろな構造物が存在し、
図５（Ｃ）に示すように画像濃度値（画像信号）にばら
つきがあるため、比較的高い分散値を示すことになる
が、４×４画素程度の小領域内では構造物の構成によっ
て濃度値（信号値）に大きなばらつきが現れない小領域
もあり、人体部分に重なる全ての小領域で高い分散値が
得られるわけではない。更に、小領域内に照射野の輪郭
を含む場合には、図５（Ｄ）に示すように、照射野絞り
に相当する低濃度部分と照射野内の部分とが１つの小領
域内に存在するために、非常に高い分散値となる。Here, the density distribution (signal distribution) in the small area has characteristics as shown in FIGS. 5A to 5D depending on which part of the image area the small area corresponds to. Become. That is, in the small area as shown in FIG. 5 (A), which corresponds to the unexposed portion in the irradiation field, the high density pixels (high signal values) are uniformly distributed in the small area, and therefore the dispersion value is high. Will be lower. Further, when the small area corresponds to the irradiation field stop portion, since the low-density pixels (low signal values) are uniformly distributed in the small area as shown in FIG. 5B,
In this case as well, the variance value is low. On the other hand, when the small area overlaps the human body, various structures exist,
As shown in FIG. 5C, the image density value (image signal) varies, so that the dispersion value is relatively high. However, in a small area of about 4 × 4 pixels, the density may vary depending on the structure of the structure. There is a small area in which a large variation does not appear in the value (signal value), and a high variance value cannot be obtained in all the small areas overlapping the human body part. Further, when the contour of the irradiation field is included in the small area, as shown in FIG. 5D, a low-density portion corresponding to the irradiation field diaphragm and a portion in the irradiation field exist in one small area. Therefore, the dispersion value is very high.
【００３１】従って、小領域で分割される画像の行又は
列方向で、分散値が非常に高い小領域を多く含む行（横
方向の小領域列）又は列（縦方向の小領域列）は、照射
野の輪郭を含む可能性が高いことになる。そこで、Ｓ４
では、分散値が所定の閾値Ｔｈ１以上である小領域（以
下、輪郭領域という。）を、所定数Ｔｈ２以上含む小領
域の行又は列を検出し、かかる行又は列を照射野の輪郭
を規定するための候補とする。Therefore, a row (horizontal small area column) or a column (vertical small area column) that includes many small areas having a very high variance value in the row or column direction of an image divided into small areas is , It is likely that the contour of the irradiation field is included. Therefore, S4
Then, a row or a column of a small area having a predetermined number Th2 or more of a small area having a variance value of a predetermined threshold Th1 or more (hereinafter referred to as a contour area) is detected, and the contour of the irradiation field is defined by the row or the column. To be a candidate for
【００３２】ところで、前記輪郭領域は、含まれる画像
信号の分散値が所定の閾値Ｔｈ１以上である小領域とし
て検出されたものであるから、輪郭を含む小領域以外で
あっても、人体の構造物の構成などによる信号ばらつき
が大きい部分に重なる小領域（例えば図７に示すように
一部分が肺野と重なる領域）では、分散値が閾値Ｔｈ１
を越えて輪郭領域として検出されることがあり、かかる
誤検出の輪郭領域に基づいて照射野の輪郭が誤認識され
る場合があるので、Ｓ５において候補に上げられた小領
域の行又は列が真に照射野の輪郭を示すものであるか否
かの正誤判定を行う。By the way, since the contour area is detected as a small area in which the variance value of the included image signal is equal to or larger than the predetermined threshold Th1, the structure of the human body is not limited to the small area including the contour. In a small area (for example, an area that partially overlaps the lung field as shown in FIG. 7) that overlaps a portion where the signal variation due to the configuration of an object is large, the variance value is the threshold value Th1.
May be detected as a contour region, and the contour of the irradiation field may be erroneously recognized based on the erroneously detected contour region. Therefore, the row or column of the small region selected as a candidate in S5 is Whether or not it really shows the contour of the irradiation field is determined.
【００３３】即ち、Ｓ４において照射野の輪郭であると
認識される小領域の行又は列は、あくまで候補であって
確かめられていないものであるので、未確定要素として
候補行，候補列としてある。Ｓ５における候補行・候補
列の正誤判定、即ち、候補として上げられたものが真に
照射野領域の輪郭であるか、照射野領域の輪郭ではなく
人体構造物の輪郭或いは人体の輪郭である可能性が高い
かの正誤判定は、以下のようにして行われる。That is, the row or column of the small area recognized as the contour of the irradiation field in S4 is only a candidate and has not been confirmed, so it is a candidate row or candidate column as an undetermined element. . Whether or not the candidate row / candidate column is correct / incorrect in S5, that is, the candidate is the contour of the irradiation field area, or the contour of the human body structure or the contour of the human body instead of the contour of the irradiation field area. Whether or not there is a high degree of accuracy is determined as follows.
【００３４】前記候補行・候補列が真に照射野の輪郭を
示すものであれば、かかる候補行・候補列の外側の領域
は照射野絞りの領域であるから、候補行・候補列よりも
それぞれ１つ外側の行・列に含まれる画素の画像信号
は、照射野絞りに対応するレベルを示すはずである。そ
こで、Ｓ５では、照射野輪郭の候補行・候補列の１つの
外側の行・列に含まれる画素値の代表値（最小値・最大
値・平均値等）を求め、かかる代表値と所定の閾値Ｔｈ
３とを比較し、代表値が閾値Ｔｈ３未満である場合に
は、その候補行・候補列は正しいものと見做し、代表値
が閾値Ｔｈ３以上である場合には、その候補行・候補列
は照射野領域の輪郭を示すものではなく、人体構造物又
は人体の輪郭である可能性が高いと判定する。候補行・
候補列が正しい場合には、１つ外側の行・列は、照射野
絞り領域であって一様に低濃度（低信号値）となるか
ら、代表値が閾値Ｔｈ３以上であるときには、真の輪郭
は更に外側にあるものと推察される。If the candidate row / candidate column truly shows the contour of the irradiation field, the area outside the candidate row / candidate column is the area of the irradiation field stop, so that it is more preferable than the candidate row / candidate column. The image signals of the pixels included in the outer one row / column should show the level corresponding to the irradiation field stop. Therefore, in S5, a representative value (minimum value, maximum value, average value, etc.) of pixel values included in one row / column outside the candidate row / candidate column of the irradiation field contour is calculated, and the representative value and the predetermined value are determined. Threshold Th
3 is compared, and if the representative value is less than the threshold value Th3, the candidate row / candidate column is considered to be correct, and if the representative value is not less than the threshold value Th3, the candidate row / candidate column. Does not indicate the contour of the irradiation field region, but determines that the contour is likely to be the contour of the human body structure or the human body. Candidate line
When the candidate column is correct, the outermost row / column is the irradiation field narrowed region and has a uniformly low density (low signal value). Therefore, when the representative value is the threshold value Th3 or more, the true value is true. The contour is presumed to be further outside.
【００３５】Ｓ５で、照射野輪郭の候補行・候補列が真
に照射野領域の輪郭に相当するものではなく、人体構造
物又は人体の輪郭である可能性が高いと判定されたとき
には、その候補行・候補列を無効とし、再度Ｓ４に戻
り、更に外側の行又は列で輪郭領域を所定数Ｔｈ２以上
含む行・列を検出し、その行・列を照射野の輪郭を規定
する候補行・候補列として更新設定させ、Ｓ５で正しい
と判定される候補行・候補列が検出されるまで、Ｓ４，
Ｓ５の処理を繰り返させる。If it is determined in S5 that the candidate row / column of the irradiation field contour does not really correspond to the contour of the irradiation field area but is highly likely to be the contour of the human body structure or the human body, the The candidate row / candidate column is invalidated, the process returns to S4 again, and a row / column that further includes a predetermined number of contour regions Th2 or more in the outer row or column is detected, and that row / column defines the contour of the irradiation field.・ Update setting is performed as a candidate column, and until a candidate row / candidate column that is determined to be correct in S5 is detected, S4,
The process of S5 is repeated.
【００３６】尚、画像の中央行，中央列から上記のよう
に順次候補行・候補列を検出していって、最終的に照射
野の輪郭となる小領域の行・列が検出できなかった場合
には、その方向での照射野絞りは行われなかったものと
見做す。Ｓ５で、照射野輪郭の候補行・候補列が正しい
と判定された場合には、前記候補行・候補列が照射野の
輪郭線を含むものであると最終的に認識し、Ｓ６におい
て、輪郭を規定する小領域の行・列よりも内側の領域
（候補行・候補列を含まない）を照射野領域として抽出
させ、輪郭を規定する小領域の行・列を含めて外側を照
射野絞り領域として除外する。It should be noted that the candidate rows / columns were sequentially detected from the center row and center column of the image as described above, and the row / column of the small area which would eventually become the contour of the irradiation field could not be detected. In this case, it is considered that the irradiation field was not narrowed in that direction. When it is determined in S5 that the candidate row / candidate column of the irradiation field contour is correct, it is finally recognized that the candidate row / candidate column includes the irradiation field contour line, and in S6, the contour is defined. The area inside the rows and columns of the small area (excluding candidate rows and columns) is extracted as the irradiation field area, and the outside including the rows and columns of the small area that defines the contour is defined as the irradiation field narrowed area. exclude.
【００３７】上記のように、輪郭を規定する小領域の行
・列を照射野領域から除くようにするのは、これにより
照射野領域が削られることがあるが、少なくとも照射野
絞りの領域が照射野領域内に僅かでも含まれてしまうこ
とを回避するためである。上記のようにして抽出された
照射野領域は、その後の画像処理条件の設定に供され、
照射野絞りの領域に対応する信号レベルに処理条件が影
響されて、所望の画像処理が行えなくなることを防止す
る。As described above, the reason why the rows and columns of the small area defining the contour are excluded from the irradiation field area is that the irradiation field area may be deleted, but at least the area of the irradiation field diaphragm is reduced. This is for avoiding even a slight inclusion in the irradiation field area. The irradiation field area extracted as described above is provided for the subsequent setting of image processing conditions,
It is prevented that the processing condition is affected by the signal level corresponding to the area of the irradiation field stop and desired image processing cannot be performed.
【００３８】例えば、図７に示すようにして、照射野領
域と照射野絞りの領域とが区別されると、照射野領域内
の画像信号に基づいて胸部放射線画像の関心領域である
肺野の領域をプロファイル情報に基づいて検出し、検出
された肺野内の画像信号のヒストグラムや累積ヒストグ
ラムに基づいて階調処理などの画像処理条件の決定を行
わせる。尚、照射野領域内の全画像信号のヒストグラム
や累積ヒストグラムから画像処理条件を設定させる構成
であっても良い。For example, when the irradiation field region and the irradiation field stop region are distinguished as shown in FIG. 7, the lung field, which is the region of interest of the chest radiographic image, is determined based on the image signal in the irradiation field region. A region is detected based on the profile information, and image processing conditions such as gradation processing are determined based on the histogram or cumulative histogram of image signals in the detected lung field. The image processing condition may be set from the histogram of all the image signals in the irradiation field area or the cumulative histogram.
【００３９】上記のような照射野領域の抽出によると、
画像信号を間引いてから用いるので処理時間を短くでき
ると共に、画像領域を小領域に分割して、かかる小領域
の中で輪郭線を含むものを検出する構成であるから、照
射野絞りが画像に対して斜めに行われても、ある程度ま
ではこれを吸収して照射野領域を抽出させることができ
る。更に、小領域内の信号分散値という際立って特徴的
となるパラメータに基づいて照射野領域を抽出させるも
のであり、例えば空間周波数のような微細な特徴を捉え
て照射野領域を抽出するものではないので、上記のよう
に処理時間短縮のために間引き画像を用いてもあまり精
度が低下することはなく、安定して精度の良い照射野領
域の抽出が行える。According to the extraction of the irradiation field area as described above,
Since it is used after thinning out the image signal, the processing time can be shortened, and the image area is divided into small areas, and the one including the contour line is detected in the small areas. Even if it is performed diagonally, the radiation field region can be extracted by absorbing it to some extent. Furthermore, it is intended to extract the irradiation field region based on a parameter that is a characteristic of the signal dispersion value in a small region, and for example, to extract the irradiation field region by capturing minute features such as spatial frequency. Therefore, even if the thinned image is used for shortening the processing time as described above, the accuracy does not decrease so much, and the irradiation field region can be stably and accurately extracted.
【００４０】ところで、前記Ｓ５における候補行・候補
列の正誤判定は、前述のような１つ外側の行・列におけ
る信号レベルに基づくものの他、候補行・候補列内の画
像信号に基づいて行わせることもできる。即ち、候補行
・候補列が正しいものであるとすれば、かかる候補行・
候補列には、それぞれ照射野絞りの領域が一部に重なっ
ているはずであり、前記照射野絞りの部分に対応する信
号値は、人体において放射線透過量の最も少ない部分
（例えば骨）に対応する信号値よりも低くなる。従っ
て、候補行・候補列に含まれる画素値の中での最小値
が、人体で最も透過量の少ない部分に対応する値よりも
小さく、照射野絞りの部分に相当するときには、候補行
・候補列として設定された小領域の並びの中に少なくと
も照射野絞りの部分が重なっていることになり、前記候
補行・候補列は正しいということになる。逆に、候補行
・候補列における最小信号値が、照射野絞りの領域に対
応するレベルほど小さくない場合には、前記候補行・候
補列は照射野領域の輪郭ではなく、人体構造物又は人体
の輪郭である可能性が高いと見做すことができ、該誤り
と判断された行・列を無効として、更に外側で分散値が
所定以上である小領域を所定数以上含む行・列を探す。By the way, the correctness / incorrectness determination of the candidate row / candidate column in S5 is performed based on the image signal in the candidate row / candidate column in addition to the signal level in the outer row / column as described above. It can also be done. That is, if the candidate row / column is correct,
The areas of the irradiation field diaphragm should overlap each part in the candidate row, and the signal value corresponding to the area of the irradiation field diaphragm corresponds to the portion (for example, bone) with the smallest radiation transmission amount in the human body. Lower than the signal value to Therefore, when the minimum value of the pixel values included in the candidate row / candidate column is smaller than the value corresponding to the portion of the human body with the least amount of transmission and corresponds to the area of the irradiation field stop, the candidate row / candidate This means that at least the irradiation field stop portion overlaps the arrangement of the small areas set as columns, and the candidate row / candidate column is correct. On the contrary, when the minimum signal value in the candidate row / candidate column is not smaller than the level corresponding to the area of the irradiation field aperture, the candidate row / candidate column is not the contour of the irradiation field area, but the human body structure or human body. It is possible to consider that there is a high possibility that it is a contour of the above, and the row / column judged as the error is invalidated, and a row / column including a predetermined number or more of small areas having a variance value of a predetermined value or more is further outside. look for.
【００４１】上記の実施例では、画像の中央から外側に
向けて照射野の輪郭を規定する候補行・候補列を順次検
出して、照射野領域の輪郭ではなく人体構造物又は人体
の輪郭である可能性が高いと判断されたときにのみ更に
外側で候補行・候補列となるところを探すようにした
が、候補行・候補列が設定される毎に正誤を判断させる
のではなく、画像内で候補行・候補列となる小領域の並
びを全て検出してから最終的にどの候補が正しいかを選
択させるようにしても良い。In the above-described embodiment, candidate rows and candidate columns that define the contour of the irradiation field are sequentially detected from the center of the image to the outside, and the contour of the human body structure or the human body is used instead of the contour of the irradiation field region. Only when it is determined that there is a high possibility, we searched for the candidate row / candidate column further outside, but instead of letting the user judge whether the candidate row / candidate column is set correctly, It is also possible to detect all the arrangements of the small areas that are the candidate rows and the candidate columns, and finally select which candidate is correct.
【００４２】例えば、図８に示すように、画像の内外方
向で複数の候補行・列が検出されたときには、最も外側
の候補行・列が正しいものと判定して選択させ、該選択
された候補行・列よりも内側の領域を照射野領域として
抽出させる。このように、外側を正しいものとして扱う
のは、輪郭線を含まないのに分散値が所定値以上となる
のは、人体構造物の構成に影響される場合であって、か
かる誤認識による輪郭は、必ず真の輪郭よりも内側の照
射野内となるからである。For example, as shown in FIG. 8, when a plurality of candidate rows / columns are detected in the inside / outside direction of the image, the outermost candidate rows / columns are judged to be correct and selected, and the selected ones are selected. An area inside the candidate row / column is extracted as an irradiation field area. In this way, the outside is treated as correct when the variance value is equal to or greater than the predetermined value even though the contour line is not included when the structure of the human body structure is affected. Is always within the irradiation field inside the true contour.
【００４３】また、照射野絞りの領域において、ノイズ
等の影響で小領域の分散値が所定以上となって、照射野
の輪郭が誤認識される惧れもあるので、照射野輪郭の候
補行・候補列の１つ内側の行・列に含まれる画素値の代
表値（最小値・最大値・平均値等）を求め、かかる代表
値と所定の閾値Ｔｈ４とを比較し、代表値が前記閾値Ｔ
ｈ４以上である場合には、その候補行・候補列は照射野
輪郭であると見做し、代表値が閾値Ｔｈ４未満である場
合には、その候補行・候補列は照射野絞り領域内のノイ
ズに基づいて誤認識された可能性が高いと判定すると良
い。上記のように、候補の内側の画素値を判別するの
は、真に照射野輪郭が認識されている場合には、その内
側は照射野領域であって、絞り領域よりも信号レベルが
高くなるはずであるからである。Further, in the area of the irradiation field diaphragm, the variance value of the small area may exceed a predetermined value due to the influence of noise and the like, and the contour of the irradiation field may be erroneously recognized. A representative value (minimum value, maximum value, average value, etc.) of pixel values included in a row / column inside one of the candidate columns is obtained, and the representative value is compared with a predetermined threshold Th4. Threshold T
If h4 or more, the candidate row / candidate column is regarded as an irradiation field contour, and if the representative value is less than the threshold value Th4, the candidate row / candidate column is within the irradiation field narrowed region. It may be determined that there is a high possibility that the recognition error is high based on noise. As described above, the pixel value inside the candidate is discriminated when the irradiation field contour is truly recognized, and the inside is the irradiation field area, and the signal level becomes higher than the diaphragm area. Because it should be.
【００４４】また、上記実施例では、照射野輪郭の候補
行・候補列を特定してから正誤判定を行うようにした
が、分散値が所定値以上であると判別された小領域内、
或いは該小領域の１つ外側又は内側の小領域の信号値の
代表値（最小値・最大値・平均値等）によって、その小
領域が照射野輪郭の一部であるか否かを判定した後、輪
郭の一部であると判定された小領域が所定数以上並ぶ行
・列を照射野の輪郭として認識するようにしても良い。
ここで、小領域単位の正誤判定は、前述の候補行・候補
列単位の正誤判定と同様に行わせることができる。Further, in the above-mentioned embodiment, the correct line is determined after specifying the candidate row / candidate column of the irradiation field contour. However, in the small area in which the variance value is determined to be equal to or more than a predetermined value,
Alternatively, it is determined whether or not the small area is a part of the contour of the irradiation field by the representative value (minimum value, maximum value, average value, etc.) of the signal values of the small area outside or inside one of the small areas. After that, a row / column in which a predetermined number or more of small areas determined to be a part of the contour are arranged may be recognized as the contour of the irradiation field.
Here, the correctness determination in small area units can be performed in the same manner as the above-described correctness determination in candidate row / candidate column units.
【００４５】更に、候補行・候補列或いは分散値が所定
値以上である小領域の外側又は内側の小領域の信号値に
基づいて正誤判定する際には、必ずしも１つ外側又は内
側の小領域である必要はなく、２つ以上外側又は内側の
小領域を近傍の小領域として、かかる小領域内の画像デ
ータに基づいて正誤判定させるようにしても良い。尚、
本実施例では、照射野領域の抽出結果に基づき画像処理
された放射線画像信号を、上記のように直ちにプリンタ
17によってハードコピーさせるようにしたが、ＣＲＴ上
に再生させたり、又は、ファイリングシステムに一旦記
憶させ、必要なときに読み出してハードコピーしたり、
ＣＲＴに表示させるようにしても良い。Further, when making an error judgment based on the signal value of a candidate row / candidate column or a small area outside or inside a small area having a variance value of a predetermined value or more, one small area outside or inside is not always required. It is not necessary that the two or more outer or inner small areas be used as neighboring small areas, and the correctness determination may be performed based on the image data in the small areas. still,
In the present embodiment, the radiation image signal image-processed based on the extraction result of the irradiation field area is immediately printed by the printer as described above.
Although it was made to make a hard copy by 17, it can be played back on a CRT, or once stored in a filing system and read out when necessary to make a hard copy.
It may be displayed on the CRT.
【００４６】また、放射線画像信号をファイリングシス
テムに記憶させる際には、画像処理済の放射線画像信号
を記憶させても良いが、処理前の放射線画像信号と照射
野領域の抽出結果（又は、抽出結果に基づく画像処理条
件）とを対にして記憶し、読み出し時に画像処理を行う
ようにしても良い。更に、本実施例では、輝尽性蛍光体
層から光電的に読み取った放射線画像信号から照射野領
域を抽出する構成としたが、輝尽性蛍光体を用いた画像
読取りに限定されるものではなく、その他の１次元又は
２次元的放射線ディテクタを用いた構成であっても良
い。When the radiation image signal is stored in the filing system, the image-processed radiation image signal may be stored, but the unprocessed radiation image signal and the extraction result of the irradiation field area (or extraction). The image processing conditions based on the result) may be stored as a pair and the image processing may be performed at the time of reading. Furthermore, in the present embodiment, the irradiation field region is extracted from the radiation image signal photoelectrically read from the stimulable phosphor layer, but it is not limited to image reading using the stimulable phosphor. Instead, it may be a configuration using another one-dimensional or two-dimensional radiation detector.
【００４７】[0047]
【発明の効果】以上説明したように本発明によると、照
射野絞りを行って撮影された放射線画像を小領域に区分
し、小領域内における信号の分散値が高い領域が照射野
領域と照射野絞り領域との境界（照射野領域の輪郭）を
含むものと見做して、照射野領域を抽出させるようにし
たので、安定した精度で簡便に照射野領域を抽出させる
ことができると共に、画像に対する斜めの照射野絞りに
対しても許容度を以て照射野領域の抽出を行わせること
ができ、更に、間引いた画像データを用いても精度を確
保できるので、間引きデータの使用によって処理時間を
短くすることができるという効果がある。As described above, according to the present invention, the radiation image captured by performing the irradiation field stop is divided into small areas, and the area in which the signal dispersion value is high is the irradiation field area and the irradiation area. Since the irradiation field area is extracted by considering it as including the boundary with the field stop area (outline of the irradiation field area), it is possible to easily extract the irradiation field area with stable accuracy. The irradiation field area can be extracted with a certain degree of tolerance even for the oblique irradiation field diaphragm with respect to the image, and the accuracy can be secured by using the thinned image data. The effect is that it can be shortened.
【図１】本発明の基本構成を示すブロック図。FIG. 1 is a block diagram showing the basic configuration of the present invention.
【図２】本発明の一実施例を示す全体システム概略図。FIG. 2 is a schematic diagram of an entire system showing an embodiment of the present invention.
【図３】実施例における照射野領域の抽出の様子を示す
フローチャート。FIG. 3 is a flowchart showing how the irradiation field area is extracted in the embodiment.
【図４】画像信号の間引きの様子を示す状態図。FIG. 4 is a state diagram showing how image signals are thinned out.
【図５】小領域毎の濃度分布の違いを示す線図。FIG. 5 is a diagram showing a difference in density distribution for each small area.
【図６】照射野絞りを伴った胸部画像における分割状態
を示す線図。FIG. 6 is a diagram showing a division state in a chest image with an irradiation field diaphragm.
【図７】候補行の正誤の例を示す線図。FIG. 7 is a diagram showing an example of correctness of a candidate row.
【図８】画像の内外方向で複数の輪郭が認識された場合
の例を示す線図。FIG. 8 is a diagram showing an example in which a plurality of contours are recognized in the inner and outer directions of an image.
【図９】プロジェクションによる肺野領域の認識の様子
を示す線図。FIG. 9 is a diagram showing how a lung field region is recognized by projection.
【図10】プロジェクションによる肺野領域の誤認識の様
子を示す線図。FIG. 10 is a diagram showing how the lung field area is erroneously recognized by projection.
１ 放射線発生源 ４ 放射線画像変換パネル ５ 光ビーム発生部 10 フォトマル 14 画像処理装置 15 ＣＰＵ 1 Radiation source 4 Radiation image conversion panel 5 Light beam generator 10 Photomaru 14 Image processing device 15 CPU
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｎ 5/238 Ｚ 9187−5Ｃ (72)発明者 土野 久憲 東京都日野市さくら町１番地 コニカ株式 会社内─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 5 Identification code Internal reference number FI Technical indication location H04N 5/238 Z 9187-5C (72) Inventor Hisonori Dono 1 Sakura-cho, Hino-shi, Tokyo Konica Stocks In the company
Claims (4)
射線の被写体各部の透過量に対応して形成される放射線
画像の照射野領域抽出装置であって、 放射線画像の画像領域を縦横に複数の小領域に分割する
小領域分割手段と、 該小領域分割手段で分割された複数の小領域毎に、小領
域内に含まれる画像データの分散値を算出する分散値算
出手段と、 該分散値算出手段で算出された分散値が所定値以上であ
る小領域を所定数以上含む小領域の縦横列を照射野の輪
郭として認識する輪郭認識手段と、 該輪郭認識手段で輪郭として認識された小領域列よりも
内側の画像領域を照射野領域として抽出する照射野領域
抽出手段と、 を含んで構成されたことを特徴とする放射線画像の照射
野領域抽出装置。1. An irradiation field area extraction device for a radiation image, which is formed in accordance with the amount of transmission of radiation that is applied to the object by subjecting the irradiation field to a subject. A small area dividing means for dividing into a plurality of small areas; a dispersion value calculating means for calculating a dispersion value of image data included in the small area for each of the plurality of small areas divided by the small area dividing means; Contour recognition means for recognizing the vertical and horizontal rows of small areas containing a predetermined number or more of small areas with the variance value calculated by the variance value calculating means being a predetermined value or more, as contours of the irradiation field, and being recognized as contours by the contour recognizing means. A radiation image irradiation field region extraction device, comprising: an irradiation field region extraction unit that extracts an image region inside the small region row as an irradiation field region.
領域内の画像データが、オリジナルの画像データを間引
いた画像データであることを特徴とする請求項１記載の
放射線画像の照射野領域抽出装置。2. An irradiation field of a radiation image according to claim 1, wherein the image data in the small area for which the variance value calculation means calculates the variance value is image data obtained by thinning out the original image data. Area extraction device.
識を、輪郭相当の小領域内若しくは前記輪郭相当の小領
域の近傍の小領域内における画像データの代表値に基づ
いて正誤判定し、誤りであると判定されたときに前記輪
郭相当の小領域に基づく最終的な輪郭認識を禁止する正
誤判定手段を設けたことを特徴とする請求項１又は２の
いずれかに記載の放射線画像の照射野領域抽出装置。3. The contour recognition of the irradiation field in the contour recognition means is judged as correct or incorrect based on a representative value of image data in a small area corresponding to the contour or in a small area near the small area corresponding to the contour, and an error is made. 3. The radiation image irradiation according to claim 1, further comprising: a correctness determination unit that prohibits final contour recognition based on the small area corresponding to the contour when it is determined to be true. Field extraction device.
で複数の輪郭が認識されたときに、前記照射野領域抽出
手段による照射野領域の抽出を最も外側の輪郭に基づい
て行わせる外側輪郭選択手段を設けたことを特徴とする
請求項１又は２のいずれかに記載の放射線画像の照射野
領域抽出装置。4. An outer contour selection for causing the irradiation field area extraction means to extract the irradiation field area based on the outermost contour when the contour recognition means recognizes a plurality of contours in the inner and outer directions of the image. A radiation image irradiation field region extraction apparatus according to claim 1 or 2, further comprising means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14577591A JP3239186B2 (en) | 1991-06-18 | 1991-06-18 | Radiation image field extraction device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14577591A JP3239186B2 (en) | 1991-06-18 | 1991-06-18 | Radiation image field extraction device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH057579A true JPH057579A (en) | 1993-01-19 |
| JP3239186B2 JP3239186B2 (en) | 2001-12-17 |
Family
ID=15392881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14577591A Expired - Fee Related JP3239186B2 (en) | 1991-06-18 | 1991-06-18 | Radiation image field extraction device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3239186B2 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5732149A (en) * | 1993-12-24 | 1998-03-24 | Konica Corporation | Apparatus for extracting an irradiation field region from a radiation image |
| WO2002051315A1 (en) * | 2000-12-22 | 2002-07-04 | Mitsubishi Space Software Co., Ltd. | Method and apparatus for cutting out chest area of band- including image |
| US7046836B2 (en) | 1998-04-07 | 2006-05-16 | Canon Kabushiki Kaisha | Image processing method apparatus and storage medium for recognition of irradiation area |
| US7263155B2 (en) | 2003-09-22 | 2007-08-28 | Canon Kabushiki Kaisha | Radiography apparatus and radiation image processing method |
| JP2011115404A (en) * | 2009-12-03 | 2011-06-16 | Canon Inc | X-ray image combining apparatus and x-ray image combining method |
| JP2013102848A (en) * | 2011-11-11 | 2013-05-30 | Konica Minolta Medical & Graphic Inc | Medical image treatment apparatus and program |
| JP2014117307A (en) * | 2012-12-13 | 2014-06-30 | Konica Minolta Inc | Radiation image processor, radiation image processing method, and program |
| JP2015211875A (en) * | 2015-07-09 | 2015-11-26 | キヤノン株式会社 | Image processing apparatus, image processing method, and computer program |
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| JP5311846B2 (en) * | 2008-02-29 | 2013-10-09 | 富士フイルム株式会社 | Image processing method and apparatus, and radiographic imaging processing method and apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5732149A (en) * | 1993-12-24 | 1998-03-24 | Konica Corporation | Apparatus for extracting an irradiation field region from a radiation image |
| US7046836B2 (en) | 1998-04-07 | 2006-05-16 | Canon Kabushiki Kaisha | Image processing method apparatus and storage medium for recognition of irradiation area |
| WO2002051315A1 (en) * | 2000-12-22 | 2002-07-04 | Mitsubishi Space Software Co., Ltd. | Method and apparatus for cutting out chest area of band- including image |
| US7263155B2 (en) | 2003-09-22 | 2007-08-28 | Canon Kabushiki Kaisha | Radiography apparatus and radiation image processing method |
| JP2011115404A (en) * | 2009-12-03 | 2011-06-16 | Canon Inc | X-ray image combining apparatus and x-ray image combining method |
| JP2013102848A (en) * | 2011-11-11 | 2013-05-30 | Konica Minolta Medical & Graphic Inc | Medical image treatment apparatus and program |
| JP2014117307A (en) * | 2012-12-13 | 2014-06-30 | Konica Minolta Inc | Radiation image processor, radiation image processing method, and program |
| JP2015211875A (en) * | 2015-07-09 | 2015-11-26 | キヤノン株式会社 | Image processing apparatus, image processing method, and computer program |
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|---|---|
| JP3239186B2 (en) | 2001-12-17 |
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