JP5177633B2 - Material identification inspection apparatus and method - Google Patents

Material identification inspection apparatus and method Download PDF

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JP5177633B2
JP5177633B2 JP2007298158A JP2007298158A JP5177633B2 JP 5177633 B2 JP5177633 B2 JP 5177633B2 JP 2007298158 A JP2007298158 A JP 2007298158A JP 2007298158 A JP2007298158 A JP 2007298158A JP 5177633 B2 JP5177633 B2 JP 5177633B2
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七三雄 金子
大典 石田
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本発明は、Ｘ線により被検査物の材質識別を行う材質識別検査装置および方法に関する。   The present invention relates to a material identification inspection apparatus and method for performing material identification of an object to be inspected by X-rays.

税関や空港における手荷物検査等において、Ｘ線を被検査物に照射し、透過したＸ線の強度分布を画像化して内部の危険物（銃器等）を検出するＸ線検査装置が従来から広く用いられている。
さらに、近年になって、被検査物の材質を識別する手段が種々提案されている（例えば特許文献１〜４）。 Conventionally, X-ray inspection equipment that detects X-ray intensity distribution of transmitted X-rays and detects internal dangerous objects (firearms, etc.) in inspection of baggage at customs and airports has been widely used. It has been.
Furthermore, in recent years, various means for identifying the material of the inspection object have been proposed (for example, Patent Documents 1 to 4).

特許文献１の「材質特定Ｘ線検査装置」は、被測定物に含まれる対象物の元素を特定して、材質を特定することを目的とする。
そのため、この発明では、図６に模式的に示すように、予め元素が既知の対象物にＸ線を照射して、透過Ｘ線の検出出力と対象物の厚みとの特性データを、照射Ｘ線のエネルギー別および元素別に求めて特性データとして特性データ格納手段（特性データメモリ５０）に格納しておき、Ｘ線源（第１，２Ｘ線管５２Ｈ，５２Ｌ）からエネルギーの異なる２つのＸ線を被測定物５１に照射し、各Ｘ線に対する透過Ｘ線を検出器（第１，２ラインセンサＸ線管５６Ｈ，５６Ｌ）で検出して検出出力レベルを求める。材質特定手段（画像メモリ５４ａ，演算，比較回路５４ｂ，制御回路５４ｃ）は、特性データを用いて２つの検出出力レベルに対応する対象物の厚みを求め、厚みが一致する元素を求める。異なるＸ線エネルギーによる検出出力レベルに対する厚みの一致から、被測定物中に含まれる対象物の元素を特定し、被測定物の材質を特定するものである。 The “material-specific X-ray inspection apparatus” of Patent Document 1 is intended to specify an element of an object included in an object to be measured and specify a material.
Therefore, in the present invention, as schematically shown in FIG. 6, X-rays are irradiated to an object whose element is known in advance, and the characteristic data of the detected output of transmitted X-rays and the thickness of the object are expressed as irradiation X Two X-rays having different energies from the X-ray sources (first and second X-ray tubes 52H and 52L) are obtained as characteristic data obtained for each line energy and element and stored in characteristic data storage means (characteristic data memory 50). To the object to be measured 51, and transmitted X-rays for each X-ray are detected by a detector (first and second line sensors X-ray tubes 56H and 56L) to obtain a detection output level. The material specifying means (image memory 54a, arithmetic / comparison circuit 54b, control circuit 54c) obtains the thickness of the object corresponding to the two detection output levels using the characteristic data, and obtains the elements having the same thickness. The element of the object contained in the object to be measured is specified from the coincidence of the thickness with the detected output level by different X-ray energy, and the material of the object to be measured is specified.

特許文献２の「内容物識別装置および内容物識別方法」は、容器，袋あるいは機器の中に存在する内容物を簡便にかつ正確に表示してその識別を行うことを目的とする。
そのため、この発明の装置は、Ｘ線透視画像信号を作成する手段、中性子画像信号を作成する手段、これらの信号を基にＸ線透視画像の中に中性子透視画像を合成して表示する手段からなるものである。 The “content identification device and content identification method” of Patent Document 2 is intended to easily and accurately display the contents present in a container, a bag, or a device for identification.
Therefore, the apparatus of the present invention comprises means for creating an X-ray fluoroscopic image signal, means for generating a neutron image signal, and means for synthesizing and displaying the neutron fluoroscopic image in the X-ray fluoroscopic image based on these signals. It will be.

特許文献３のＸ線ＣＴ装置は、端部効果によるアーチファクトを軽減し、診断能の高い再構成画像を得ることを目的とする。
そのため、この発明の装置は、図７に示すように、被検体６０のある断面に、その周囲の多数の角度方向からＸ線源６１によりＸ線を照射し、透過したＸ線を多数のＸ線検出素子を配列してなる多チャンネルＸ線検出器６２で検出し、デジタルデータとして測定すると共に、測定したデジタルデータから被検体６０の断面の像を再構成するＸ線ＣＴ装置において、計測したＸ線強度値であるデジタルデータあるいはそれに相当する値のうち、隣接する複数の値から補間操作によって１Ｘ線検出素子内を細分化した後、細分化したＸ線強度値のそれぞれをログ変換し、ログ変換した値の加重平均値を１Ｘ線検出素子でのＸ線吸収係数の線積分値あるいはそれに相当する値として出力する補正処理手段を具備し、補正処理手段の出力値を用いて画像再構成するものである。 The X-ray CT apparatus of Patent Document 3 aims to reduce artifacts due to end effects and obtain a reconstructed image with high diagnostic ability.
Therefore, as shown in FIG. 7, the apparatus of the present invention irradiates a cross section of a subject 60 with X-rays from an X-ray source 61 from a plurality of angular directions around the subject 60, and transmits the transmitted X-rays to a large number of X-rays. Detected by a multi-channel X-ray detector 62 in which line detection elements are arranged, measured as digital data, and measured by an X-ray CT apparatus that reconstructs a cross-sectional image of the subject 60 from the measured digital data. After subdividing the inside of the 1 X-ray detection element by interpolating operation from a plurality of adjacent values among digital data that is X-ray intensity values or values corresponding thereto, log conversion is performed for each of the subdivided X-ray intensity values, Correction processing means for outputting a weighted average value of the log-converted values as a line integral value of the X-ray absorption coefficient at the 1 X-ray detection element or a value corresponding thereto, and using the output value of the correction processing means It is intended to re-configuration.

特許文献４の「高速中性子及び連続エネルギー・スペクトルＸ線により材料識別する方法及びその装置」は、高速中性子及び連続エネルギー・スペクトルＸ線による材料識別の方法と装置を提供することを目的とする。
そのため、この発明では、図８に模式的に示すように、（ａ）高速中性子源７１及び連続エネルギー・スペクトルＸ線源７４でそれぞれ産生された高速中性子ビーム７２及び連続エネルギー・スペクトルＸ線ビーム７５を被検対象７７に照射する；（ｂ）Ｘ線検出器アレー７６及び中性子検出器アレー７３にて、透過したＸ線ビーム７５及び高速中性子ビーム７２の強度を直接計測する；（ｃ）被検対象７７の異なる材料を透過した中性子ビームとＸ線ビームの減衰差によって形成された曲線により、被検対象の材料に対して材料識別を行う；ステップを含む。高速中性子と連続エネルギー・スペクトルＸ線との透過減衰強度が異なるように構成され、被検対象の厚さと無関係に被検対象の等効原子番号Ｚとのみ関係するｎ−Ｘ曲線を利用して材料識別を行うものである。 An object of the “method and apparatus for identifying materials by fast neutrons and continuous energy spectrum X-rays” in Patent Document 4 is to provide a method and apparatus for identifying materials by fast neutrons and continuous energy spectrum X-rays.
Therefore, in the present invention, as schematically shown in FIG. 8, (a) a fast neutron beam 72 and a continuous energy spectrum X-ray beam 75 produced by a fast neutron source 71 and a continuous energy spectrum X-ray source 74, respectively. (B) The intensity of the transmitted X-ray beam 75 and fast neutron beam 72 is directly measured by the X-ray detector array 76 and the neutron detector array 73; (c) the test Material identification is performed on the material to be examined by a curve formed by the attenuation difference between the neutron beam and the X-ray beam transmitted through different materials of the object 77; The transmission attenuation intensity of fast neutrons and continuous energy spectrum X-rays are configured to be different from each other, using an n-X curve that is related only to the isotropic atomic number Z of the test object regardless of the thickness of the test object. Material identification is performed.

特開平１０−１０４１７５号公報、「材質特定Ｘ線検査装置」Japanese Patent Laid-Open No. 10-104175, “Material Specific X-ray Inspection Device” 特開平１１−６４２４８号公報、「内容物識別装置および内容物識別方法」Japanese Patent Laid-Open No. 11-64248, “Content Identification Device and Content Identification Method” 特許第２７９８９９８号公報、「Ｘ線ＣＴ装置」Japanese Patent No. 2798998, “X-ray CT apparatus” 特開２００７−１２７６１７号公報、「高速中性子及び連続エネルギー・スペクトルＸ線により材料識別する方法及びその装置」Japanese Patent Application Laid-Open No. 2007-127617, “Method and apparatus for identifying material by fast neutron and continuous energy spectrum X-ray”

上述した特許文献３のようなＸ線ＣＴ装置（Ｘ線断層撮影装置）では、検査対象物の周囲を１８０度回転させて対象物の断層データを取得し、これからコンピュータによって画像を再構築して二次元断面像を得ることができる。さらに内部にある物質を識別することもできる。
しかし、Ｘ線ＣＴ装置では、検査対象物の周囲、１８０度分のデータを取得する必要上Ｘ線と検出器を回転させるための回転機構を有するため、検査速度が遅い。さらにＸ線エネルギーもスペクトルが連続であるため、物質識別の精度が低かった。 In the X-ray CT apparatus (X-ray tomography apparatus) as in Patent Document 3 described above, the tomographic data of the object is acquired by rotating the periphery of the inspection object by 180 degrees, and the image is reconstructed from this by using a computer. A two-dimensional cross-sectional image can be obtained. In addition, it is possible to identify substances inside.
However, since the X-ray CT apparatus has a rotation mechanism for rotating the X-ray and the detector around the inspection object, it is necessary to acquire data for 180 degrees, so the inspection speed is slow. Furthermore, since the spectrum of the X-ray energy is continuous, the accuracy of substance identification is low.

また、上述した特許文献１では、材質識別はできるが予め元素が既知の対象物に関して、Ｘ線の検出出力と対象物の厚みとの特性データを求めておく必要があり、特許文献２と特許文献４では、中性子ビームを用いた中性子透視画像が別途必要となる問題点があった。   Further, in Patent Document 1 described above, it is necessary to obtain characteristic data on the detection output of the X-ray and the thickness of the object with respect to the object whose element can be identified but whose element is already known. In Reference 4, there is a problem that a neutron fluoroscopic image using a neutron beam is separately required.

本発明は、上述した問題点を解決するために創案されたものである。すなわち、本発明の目的は、税関や空港における手荷物検査等において、被検査物を連続的に検査して、短時間にその材質を識別することができ、かつ予めＸ線の検出出力と対象物の厚みとの特性データを求める必要がない材質識別検査装置および方法を提供することにある。   The present invention has been developed to solve the above-described problems. That is, it is an object of the present invention to continuously inspect an object to be inspected in customs or baggage inspection at an airport, etc., to identify the material in a short time, and to detect an X-ray detection output and an object in advance. It is an object of the present invention to provide a material identification inspection apparatus and method that do not require to obtain characteristic data on the thickness of the material.

本発明によれば、被検査物を内部に有する荷物を搬送する搬送装置と、
該荷物の搬送方向に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線を、同時又は時間をずらして照射するＸ線照射装置と、
前記荷物の複数の断面に対する複数の照射方向のそれぞれについて、透過Ｘ線強度分布を２以上のエネルギー領域に弁別して計測し記憶するＸ線計測装置と、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各断面の擬似断層像を作成する擬似断層像作成手段と、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各照射方向の透過像を作成する透過像作成手段と、
前記擬似断層像と前記透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去する偽画像除去手段と、
偽画像を除去した前記擬似断層像内の被検査物に関して、２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度から、前記被検査物の実効原子番号と電子密度を算出し、これから被検査物の材質を識別する識別演算装置と、を備えたことを特徴とする材質識別検査装置が提供される。 According to the present invention, a transport device for transporting a load having an inspection object inside,
An X-ray irradiation apparatus that irradiates linear incident X-rays having a predetermined energy distribution at the same time or at different times from a plurality of irradiation directions orthogonal to the load carrying direction;
And X-ray measuring device for each of the radiation directions, to measure and discriminate the transmitted X-ray intensity distribution into two or more energy area storage for a plurality of cross-section of the cargo,
A pseudo tomographic image creating means for creating a pseudo tomographic image of each cross section from a transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections;
A transmission image creating means for creating a transmission image in each irradiation direction from a transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections;
A false image removing unit that combines the pseudo tomographic image and the transmission image, and removes the false image included in the pseudo tomographic image from the presence / absence information of the object by the transmission image;
With respect to the inspection object in the pseudo tomographic image from which the false image has been removed, the effective atomic number and electron density of the inspection object are calculated from the intensities of incident X-rays and transmission X-rays in two or more energy regions, and from this, There is provided a material identification inspection device comprising an identification operation device for identifying a material of an inspection object.

本発明の好ましい実施形態によれば、前記識別演算装置は、偽画像を除去した前記擬似断層像から、前記複数の照射方向の被検査物の厚さｘを特定し、
前記２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度と前記厚さから、各エネルギー領域における２以上の減弱係数μを求め、
光電効果、コンプトン効果及び減弱係数の関係から実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物の材質を識別する。 According to a preferred embodiment of the present invention, the identification calculation device specifies the thickness x of the inspection object in the plurality of irradiation directions from the pseudo tomographic image from which the false image is removed,
From the intensity of incident X-rays and transmitted X-rays in the two or more energy regions and the thickness, obtain an attenuation coefficient μ of two or more in each energy region,
The effective atomic number Z eff and the electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient, and the material of the object to be inspected is identified therefrom.

また本発明によれば、被検査物を内部に有する荷物を搬送し、
該荷物の搬送方向に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線を、同時又は時間をずらして照射し、
前記荷物の複数の断面に対する複数の照射方向のそれぞれについて、透過Ｘ線強度分布を２以上のエネルギー領域に弁別して計測し記憶し、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各断面の擬似断層像を作成し、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各照射方向の透過像を作成し、
前記擬似断層像と前記透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去し、
偽画像を除去した前記擬似断層像内の被検査物に関して、２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度から、前記被検査物の実効原子番号と電子密度を算出し、これから被検査物の材質を識別する、ことを特徴とする材質識別検査方法が提供される。 Further, according to the present invention, a load having an inspection object inside is transported,
Irradiate linear incident X-rays having a predetermined energy distribution simultaneously or at different times from a plurality of irradiation directions orthogonal to the carrying direction of the luggage,
For each of a plurality of irradiation directions for a plurality of cross sections of the luggage , the transmitted X-ray intensity distribution is measured and stored in two or more energy regions,
From the transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections, a pseudo tomographic image of each cross section is created,
From the transmission X-ray intensity distribution in a plurality of irradiation directions for the plurality of cross-sections, create a transmission image in each irradiation direction,
Combining the pseudo tomogram and the transmission image, removing the false image included in the pseudo tomogram from the presence / absence information of the object by the transmission image,
With respect to the inspection object in the pseudo tomographic image from which the false image has been removed, the effective atomic number and electron density of the inspection object are calculated from the intensities of incident X-rays and transmission X-rays in two or more energy regions, and from this, There is provided a material identification inspection method characterized by identifying a material of an inspection object.

本発明の好ましい実施形態によれば、偽画像を除去した前記擬似断層像から、前記複数の照射方向の被検査物の厚さｘを特定し、
前記２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度と前記厚さから、各エネルギー領域における２以上の減弱係数μを求め、
光電効果、コンプトン効果及び減弱係数の関係から実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物の材質を識別する。 According to a preferred embodiment of the present invention, the thickness x of the inspection object in the plurality of irradiation directions is specified from the pseudo tomographic image from which the false image is removed,
From the intensity of incident X-rays and transmitted X-rays in the two or more energy regions and the thickness, obtain an attenuation coefficient μ of two or more in each energy region,
The effective atomic number Z eff and the electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient, and the material of the object to be inspected is identified therefrom.

上述した本発明の装置と方法によれば、搬送装置、Ｘ線照射装置およびＸ線計測装置により、被検査物を内部に有する荷物を搬送しながら、搬送方向に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線を、同時又は時間をずらして照射し、前記荷物の複数の断面に対する複数方向の透過Ｘ線強度分布を２以上のエネルギー領域に弁別して計測し記憶するので、被検査物を連続的に検査して、短時間に結果を得ることができる。   According to the apparatus and method of the present invention described above, while transporting a load having an object to be inspected by a transport device, an X-ray irradiation device, and an X-ray measurement device, from a plurality of irradiation directions orthogonal to the transport direction, Irradiate linear incident X-rays having a predetermined energy distribution simultaneously or at different times, and measure and store transmission X-ray intensity distributions in a plurality of directions with respect to a plurality of cross sections of the load into two or more energy regions. Therefore, the inspection object can be continuously inspected and the result can be obtained in a short time.

また、擬似断層像作成手段、透過像作成手段および偽画像除去手段により、前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各断面の擬似断層像と、前記各照射方向の透過像とを作成し、擬似断層像と透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去するので、検査速度を落とさずに偽画像を除去して、擬似断層像の検出精度を高めることができる。   Further, the pseudo tomographic image creating means, the transmission image creating means, and the pseudo image removing means are configured to obtain a pseudo tomographic image of each cross section from the transmission X-ray intensity distribution in the plurality of irradiation directions with respect to the plurality of cross sections, and each irradiation direction. Create a transmission image, combine the pseudo tomographic image and the transmission image, and remove the false image included in the pseudo tomographic image from the presence or absence information of the object by the transmission image, so remove the false image without slowing down the inspection speed, The detection accuracy of the pseudo tomogram can be improved.

さらに、識別演算装置により、偽画像を除去した前記擬似断層像内の被検査物に関して、２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度から、前記被検査物の実効原子番号と電子密度を算出し、これから被検査物の材質を識別するので、短時間にその材質を識別することができ、かつ予めＸ線の検出出力と対象物の厚みとの特性データを求める必要がない。   Furthermore, the effective atomic number and the electron of the inspection object are obtained from the intensities of incident X-rays and transmission X-rays in two or more energy regions with respect to the inspection object in the pseudo tomographic image from which the false image is removed by the identification arithmetic unit. Since the density is calculated and the material of the object to be inspected is identified from the density, the material can be identified in a short time, and there is no need to obtain characteristic data of the X-ray detection output and the thickness of the object in advance.

以下、本発明の好ましい実施形態を図面を参照して説明する。なお各図において、共通する部分には同一の符号を付し、重複した説明は省略する。   Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

はじめに本発明の原理について説明する。
図１は、本発明で使用するＸ線管とＸ線検出器のスペクトル図である。
この図において、横軸はＸ線のエネルギー、１はＸ線管から放射される入射Ｘ線の強度分布、２はエネルギー弁別機能付きＸ線検出器による入射Ｘ線の検出強度分布、３はある物質を透過した透過Ｘ線のＸ線検出器による検出強度分布である。 First, the principle of the present invention will be described.
FIG. 1 is a spectrum diagram of an X-ray tube and an X-ray detector used in the present invention.
In this figure, the horizontal axis is X-ray energy, 1 is the intensity distribution of incident X-rays emitted from the X-ray tube, 2 is the intensity distribution of incident X-rays detected by the X-ray detector with energy discrimination function, and 3 is It is a detection intensity distribution by the X-ray detector of the transmission X-ray which permeate | transmitted the substance.

この図から明らかなように、Ｘ線管から放射されるＸ線の強度分布１は、ある波長領域において、連続した連続Ｘ線である。
Ｘ線の波長は、約０．０１〜１００Å（１０-１２〜１０-８ｍ）程度であり、波長λ［Å］とＸ線エネルギーＥ［ｋｅＶ］との間には、式（１）の関係がある。
Ｅ＝１２．４／λ・・・（１）
従って、波長λ［Å］と光量子エネルギーＥ［ｋｅＶ］は１対１で対応している。 As is apparent from this figure, the intensity distribution 1 of X-rays emitted from the X-ray tube is continuous X-rays in a certain wavelength region.
The wavelength of the X-ray is about 0.01 to 100 Å (10 −12 to 10 −8 m), and between the wavelength λ [Å] and the X-ray energy E [keV], the equation (1) There is a relationship.
E = 12.4 / λ (1)
Therefore, there is a one-to-one correspondence between the wavelength λ [Ｖ] and the photon energy E [keV].

図１において、Ｘ線エネルギーＥ１，Ｅ２の２種の入射Ｘ線（強度Ｉ１０，Ｉ２０）を厚さｘの物質に照射し、その透過Ｘ線の強度Ｉ１，Ｉ２を計測すると、以下の関係がある。
Ｉ１＝Ｉ１０ｅｘｐ（−μ１ｘ）・・・（２ａ）
Ｉ２＝Ｉ２０ｅｘｐ（−μ２ｘ）・・・（２ｂ）
ここで、μ１，μ２はＸ線エネルギーＥ１，Ｅ２における減弱係数（又は線吸収係数）である。 In FIG. 1, two types of incident X-rays (intensities I 10 and I 20 ) of X-ray energies E 1 and E 2 are irradiated onto a substance having a thickness x, and the intensities I 1 and I 2 of the transmitted X-rays are measured. Then, there is the following relationship.
I 1 = I 10 exp (−μ 1 x) (2a)
I 2 = I 20 exp (−μ 2 x) (2b)
Here, μ 1 and μ 2 are attenuation coefficients (or linear absorption coefficients) in the X-ray energies E 1 and E 2 .

上記（２ａ）（２ｂ）の式から、厚さｘが既知であれば、入射Ｘ線（強度Ｉ１０，Ｉ２０）と透過Ｘ線強度（Ｉ１，Ｉ２）から減弱係数μ１，μ２を求めることができる。 From the above equations (2a) and (2b), if the thickness x is known, the attenuation coefficient μ 1 , μ is determined from the incident X-ray (intensities I 10 , I 20 ) and the transmitted X-ray intensity (I 1 , I 2 ). 2 can be obtained.

また、減弱係数μ１，μ２は、光電効果とコンプトン効果の和であり、以下の関係がある。
μ１＝ρｅＺｅｆｆ ４Ａ１＋ρｅＢ１・・・（３ａ）
μ２＝ρｅＺｅｆｆ ４Ａ２＋ρｅＢ２・・・（３ｂ） The attenuation coefficients μ 1 and μ 2 are the sum of the photoelectric effect and the Compton effect, and have the following relationship.
μ 1 = ρ e Z eff 4 A 1 + ρ e B 1 (3a)
μ 2 = ρ e Z eff 4 A 2 + ρ e B 2 (3b)

ここで、Ｚｅｆｆは物質の実効原子番号、ρｅは物質の電子密度、Ａ１，Ａ２，Ｂ１，Ｂ２は、実効原子番号によって決まる比例定数である。
減弱係数μ１，μ２を実験的に求めることにより、上記式（３ａ）（３ｂ）において、Ａ１，Ａ２，Ｂ１，Ｂ２は理論的に求まるため、２つの未知数Ｚｅｆｆ，ρｅを求めることができる。 Here, Z eff is the effective atomic number of the substance, ρ e is the electron density of the substance, and A 1 , A 2 , B 1 , and B 2 are proportional constants determined by the effective atomic number.
By experimentally determining the attenuation coefficients μ 1 and μ 2 , A 1 , A 2 , B 1 , and B 2 are theoretically determined in the above formulas (3a) and (3b), so two unknowns Z eff and ρ e can be obtained.

図２は、本発明による材質識別検査装置の第１実施形態を示す構成図である。この図において、本発明の材質識別検査装置１０は、搬送装置１２、Ｘ線照射装置１４、Ｘ線計測装置１６、擬似断層像作成手段１８、透過像作成手段１９、偽画像除去手段２０及び識別演算装置２２を備える。   FIG. 2 is a block diagram showing a first embodiment of the material identification inspection apparatus according to the present invention. In this figure, the material identification inspection apparatus 10 of the present invention includes a transport device 12, an X-ray irradiation device 14, an X-ray measurement device 16, a pseudo tomographic image creation means 18, a transmission image creation means 19, a false image removal means 20, and an identification. An arithmetic device 22 is provided.

搬送装置１２は、例えばベルトコンベアであり、被検査物５を内部に有する荷物６（例えば旅行用ケース）を水平（この図でＺ方向）に搬送する。   The transport device 12 is, for example, a belt conveyor, and transports a load 6 (for example, a travel case) having the inspection object 5 therein horizontally (in the Z direction in this figure).

Ｘ線照射装置１４は、荷物６の搬送方向（Ｚ方向）に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線７を、同時又は時間をずらして照射する。入射Ｘ線７のエネルギー分布は、例えば図１に１で示した入射Ｘ線の連続した強度分布であるのがよい。   The X-ray irradiation device 14 irradiates linear incident X-rays 7 having a predetermined energy distribution simultaneously or at different times from a plurality of irradiation directions orthogonal to the conveyance direction (Z direction) of the luggage 6. The energy distribution of the incident X-ray 7 is preferably a continuous intensity distribution of the incident X-ray indicated by 1 in FIG.

またこの例において、Ｘ線照射装置１４は、垂直下向き、斜め上向き、及び斜め下向きに固定配置された３台のＸ線管１５ａ，１５ｂ，１５ｃであり、搬送方向に直交する断面内で荷物６に対し所定のエネルギー分布の入射Ｘ線７を線状かつ扇状に照射するようになっている。
なお、３台のＸ線管１５ａ，１５ｂ，１５ｃのＺ方向位置は、この例では異なるが、同一の断面内に配置してもよい。 In this example, the X-ray irradiation device 14 includes three X-ray tubes 15a, 15b, and 15c that are fixedly arranged vertically downward, obliquely upward, and obliquely downward. On the other hand, incident X-rays 7 having a predetermined energy distribution are irradiated linearly and in a fan shape.
The X-direction positions of the three X-ray tubes 15a, 15b, and 15c are different in this example, but may be arranged in the same cross section.

Ｘ線計測装置１６は、上述したエネルギー弁別機能付きＸ線検出器であり、荷物６の複数の断面に対する複数の照射方向（この例では３つの照射方向）のそれぞれについて、透過Ｘ線の強度分布Ｉ１，Ｉ２を２以上のエネルギー領域Ｅ１，Ｅ２に弁別して計測し、所定の記憶装置（例えばＰＣのハードディスク）に記憶する。
またこの例において、Ｘ線計測装置１６は、３台のＸ線管１５ａ，１５ｂ，１５ｃに対向するように水平方向と垂直方向に固定配置された３台の線状検出器１７ａ，１７ｂ，１７ｃである。各線状検出器１７ａ，１７ｂ，１７ｃの分解能は高いほどよく、例えば、長さ１．２ｍの場合に、４ｍｍピッチで２５６点の独立したＸ線検出器を備えることにより、Ｘ線管１台当たり２５６点の透過Ｘ線の強度分布Ｉ１，Ｉ２を同時に計測することができる。
The X-ray measurement device 16 is the above-described X-ray detector with an energy discrimination function , and the transmitted X-ray intensity distribution for each of a plurality of irradiation directions (three irradiation directions in this example) with respect to a plurality of cross sections of the luggage 6. I 1 and I 2 are discriminated into two or more energy regions E 1 and E 2 , measured, and stored in a predetermined storage device (for example, a hard disk of a PC).
In this example, the X-ray measuring device 16 includes three linear detectors 17a, 17b, and 17c fixedly arranged in the horizontal and vertical directions so as to face the three X-ray tubes 15a, 15b, and 15c. It is. The higher the resolution of each of the linear detectors 17a, 17b, and 17c, the better. For example, in the case of a length of 1.2 m, by providing 256 independent X-ray detectors at a pitch of 4 mm, The intensity distributions I 1 and I 2 of 256 transmitted X-rays can be measured simultaneously.

擬似断層像作成手段１８、透過像作成手段１９、偽画像除去手段２０及び識別演算装置２２は、１台又は複数のコンピュータ（ＰＣ）で構成され、入力装置２３（例えば、キーボード、マウス等）、出力装置２４（例えば、画像表示装置、プリンタ等）および共通の記憶装置２５（例えばハードディスク）を備える。   The pseudo tomographic image creating means 18, the transmission image creating means 19, the false image removing means 20 and the identification calculation device 22 are composed of one or a plurality of computers (PC), and an input device 23 (for example, a keyboard, a mouse, etc.), An output device 24 (for example, an image display device, a printer, etc.) and a common storage device 25 (for example, a hard disk) are provided.

擬似断層像作成手段１８は、複数の断面に対する複数（この例で３）の照射方向の透過Ｘ線強度分布Ｉ１，Ｉ２から、荷物６の各断面の擬似断層像を作成する。
透過像作成手段１９は、複数の断面に対する複数（この例で３）の照射方向の透過Ｘ線強度分布から、各照射方向の荷物６の透過像を作成する。
偽画像除去手段２０は、擬似断層像と透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去する。 The pseudo tomographic image creating means 18 creates a pseudo tomographic image of each cross section of the luggage 6 from a plurality (three in this example) of transmitted X-ray intensity distributions I 1 and I 2 with respect to a plurality of cross sections.
The transmission image creating means 19 creates a transmission image of the luggage 6 in each irradiation direction from a plurality of (three in this example) transmission X-ray intensity distributions in a plurality of sections.
The false image removing unit 20 combines the pseudo tomographic image and the transmission image, and removes the false image included in the pseudo tomographic image from the presence / absence information of the object based on the transmission image.

識別演算装置２２は、偽画像を除去した擬似断層像内の被検査物に関して、２以上のエネルギー領域Ｅ１，Ｅ２における入射Ｘ線７と透過Ｘ線の強度Ｉ１０，Ｉ２０、Ｉ１，Ｉ２から、被検査物５の実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物５の材質を識別する。 The discriminating operation device 22 relates to the inspected object in the pseudo tomographic image from which the false image is removed, and the intensities I 10 , I 20 and I 1 of the incident X-ray 7 and the transmitted X-ray in the two or more energy regions E 1 and E 2 . , I 2 , the effective atomic number Z eff and the electron density ρ e of the inspection object 5 are calculated, and the material of the inspection object 5 is identified from this.

識別演算装置２２は、偽画像を除去した擬似断層像から、複数（この例で３）の照射方向の被検査物の厚さｘを特定する。この特定は、擬似断層像の画像から容易にできる。
次いで、２以上のエネルギー領域Ｅ１，Ｅ２における入射Ｘ線７と透過Ｘ線８の強度と厚さｘから、上述した式（２ａ）（２ｂ）により、各エネルギー領域Ｅ１，Ｅ２における２以上の減弱係数μ１，μ２を求める。
次に、光電効果、コンプトン効果及び減弱係数の関係（上記（３ａ）（３ｂ）の式）から、実効原子番号Ｚｅｆｆと電子密度ρｅを算出する。被検査物５の材質は、実効原子番号Ｚｅｆｆと電子密度ρｅから一般的に容易に特定でき識別が完了する。 The identification calculation device 22 specifies the thickness x of the inspection object in a plurality (3 in this example) of the irradiation direction from the pseudo tomographic image from which the false image is removed. This identification can be easily made from the pseudo tomographic image.
Then, two or more energy region E 1, strength and thickness x of the incident X-ray 7 and transmitted X-ray 8 in E 2, by the above-mentioned formula (2a) (2b), in each energy range E 1, E 2 Obtain attenuation coefficients μ 1 and μ 2 of 2 or more.
Next, the effective atomic number Z eff and the electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient (the expressions (3a) and (3b) above). The material of the inspected object 5 can be generally easily identified from the effective atomic number Z eff and the electron density ρ e , and the identification is completed.

図３は、本発明の材質識別検査方法を示す全体フロー図であり、図４は、本発明の方法の模式的説明図である。
図３に示すように、本発明の材質識別検査方法は、上述した装置を用い、搬送ステップＳ１、照射ステップＳ２、計測ステップＳ３、擬似断層像作成ステップＳ４、透過像作成ステップＳ５、偽画像除去ステップＳ６および材質識別ステップＳ７からなる。 FIG. 3 is an overall flowchart showing the material identification inspection method of the present invention, and FIG. 4 is a schematic explanatory view of the method of the present invention.
As shown in FIG. 3, the material identification inspection method of the present invention uses the above-described apparatus, and includes a transport step S1, an irradiation step S2, a measurement step S3, a pseudo tomographic image creation step S4, a transmission image creation step S5, and a false image removal. It consists of step S6 and material identification step S7.

搬送ステップＳ１では、例えばベルトコンベアにより被検査物５を内部に有する荷物６を水平に搬送する。図４（Ａ）は、被検査物５が、直方体５ａ，５ｂ、円柱５ｃおよび球５ｄである場合を示している、   In the transport step S1, the luggage 6 having the inspection object 5 therein is transported horizontally by, for example, a belt conveyor. FIG. 4A shows a case where the inspection object 5 is a rectangular parallelepiped 5a, 5b, a cylinder 5c, and a sphere 5d.

照射ステップＳ２では、荷物６の搬送方向（Ｚ方向）に直交する複数（この例で３）の照射方向から、所定のエネルギー分布１を有する線状の入射Ｘ線７を、同時又は時間をずらして照射する。
計測ステップＳ３では、荷物６の複数の断面（この例では４断面）に対する複数方向の透過Ｘ線の強度分布Ｉ１，Ｉ２を２以上のエネルギー領域Ｅ１，Ｅ２に弁別して計測し、所定の記憶装置（例えばＰＣのハードディスク）に記憶する。 In the irradiation step S2, linear incident X-rays 7 having a predetermined energy distribution 1 are simultaneously or shifted from a plurality of (in this example, 3) irradiation directions orthogonal to the carrying direction (Z direction) of the load 6. Irradiate.
In the measurement step S3, the intensity distributions I 1 and I 2 of transmitted X-rays in a plurality of directions with respect to a plurality of cross sections (4 cross sections in this example) of the luggage 6 are discriminated into two or more energy regions E 1 and E 2 and measured. The data is stored in a predetermined storage device (for example, a hard disk of a PC).

擬似断層像作成ステップＳ４では、複数の断面（この例では４断面）に対する複数の照射方向の透過Ｘ線強度分布Ｉ１，Ｉ２から、各断面の擬似断層像を作成する。
この擬似断層像の作成手段は、従来のＸ線ＣＴ装置における断面像を再構成方法と同一である。しかし、本発明では、Ｘ線ＣＴ装置と相違し、Ｘ線照射装置１４が固定されているため、Ｘ線計測装置１６で得られる透過Ｘ線の強度分布Ｉ１，Ｉ２の点数が相対的に少なく（例えば、４ｍｍピッチで２５６点×３＝７６８点）、かつＸ線の照射方向も限られている。
そのため、図４（Ｂ）に示すように、擬似断層像作成ステップＳ４で得られる擬似断層像３１は、被検査物５の正確な形状を再現することが難しく、被検査物５の周辺や被検査物５の存在しない位置に偽画像３２を含む場合が多い。 In the pseudo tomographic image creation step S4, a pseudo tomographic image of each cross section is created from the transmitted X-ray intensity distributions I 1 and I 2 in a plurality of irradiation directions with respect to a plurality of cross sections (four cross sections in this example).
This pseudo tomographic image creating means is the same as the method for reconstructing a cross-sectional image in a conventional X-ray CT apparatus. However, in the present invention, unlike the X-ray CT apparatus, since the X-ray irradiation apparatus 14 is fixed, the scores of the transmitted X-ray intensity distributions I 1 and I 2 obtained by the X-ray measurement apparatus 16 are relatively high. (For example, 256 points × 3 = 768 points at a pitch of 4 mm) and the X-ray irradiation direction is limited.
Therefore, as shown in FIG. 4B, the pseudo tomographic image 31 obtained in the pseudo tomographic image creation step S4 is difficult to reproduce the accurate shape of the inspection object 5, and the periphery of the inspection object 5 and the object In many cases, the false image 32 is included at a position where the inspection object 5 does not exist.

この偽画像３２を含む擬似断層像３１に基づき、後述する材質識別ステップＳ７で材質を識別すると、偽画像３２により本来存在しないような材質を検出してしまい材質識別の精度が低下する可能性がある。
そこで、本発明では、透過像作成ステップＳ５において、複数の断面に対する複数（この例で３）の照射方向の透過Ｘ線強度分布Ｉ１，Ｉ２から、Ｘ線照射装置１４による各照射方向の荷物６の透過像３３を作成する。図４（Ｃ）に示すように、この透過像３３は、直方体５ａ，５ｂ、円柱５ｃ、球５ｄにそれぞれ対応する透過像３４a、３４ｂ、３４ｃ、３４ｄからなる。透過像３３は、荷物６を透過した透過Ｘ線８の強度分布そのままであるため、被検査物５の存在しない部分に偽画像は発生しない。
次いで、本発明では、偽画像除去ステップＳ６において、擬似断層像３１と透過像３３（３４a、３４ｂ、３４ｃ、３４ｄ）を組み合わせ、透過像３３による物体の有無情報から擬似断層像に含まれる偽画像３２を除去する。これにより、図４（Ｄ）に模式的に示すように、被検査物５の存在しない部分の偽画像をなくし、かつ被検査物５の周囲の偽画像も除去して被検査物５の断面形状をより正確に再現した擬似断層像３１を得ることができる。 If a material is identified in the material identification step S7 described later based on the pseudo tomogram 31 including the false image 32, a material that does not originally exist may be detected from the false image 32, and the accuracy of material identification may be reduced. is there.
Therefore, in the present invention, in the transmission image creation step S5, the transmission X-ray intensity distributions I 1 and I 2 in a plurality of (3 in this example) irradiation directions with respect to a plurality of cross-sections are measured in the respective irradiation directions. A transmission image 33 of the luggage 6 is created. As shown in FIG. 4C, the transmission image 33 includes transmission images 34a, 34b, 34c, and 34d corresponding to the rectangular parallelepipeds 5a and 5b, the cylinder 5c, and the sphere 5d, respectively. Since the transmitted image 33 is the intensity distribution of the transmitted X-rays 8 that have passed through the load 6, the false image does not occur in a portion where the inspection object 5 does not exist.
Next, in the present invention, in the false image removal step S6, the pseudo tomographic image 31 and the transmission image 33 (34a, 34b, 34c, 34d) are combined, and the pseudo image included in the pseudo tomographic image from the presence / absence information of the object by the transmission image 33. 32 is removed. Thereby, as schematically shown in FIG. 4D, the false image of the portion where the inspection object 5 does not exist is eliminated, and the false image around the inspection object 5 is also removed, and the cross section of the inspection object 5 is removed. A pseudo tomographic image 31 in which the shape is reproduced more accurately can be obtained.

材質識別ステップＳ７では、偽画像を除去した擬似断層像内の被検査物に関して、２以上のエネルギー領域Ｅ１，Ｅ２における入射Ｘ線７と透過Ｘ線の強度Ｉ１０，Ｉ２０、Ｉ１，Ｉ２から、被検査物５の実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物５の材質を識別する。 In the material identification step S7, the intensities of incident X-rays 7 and transmitted X-rays I 10 , I 20 , I 1 in two or more energy regions E 1 , E 2 with respect to the inspected object in the pseudo tomographic image from which the false images are removed. , I 2 , the effective atomic number Z eff and the electron density ρ e of the inspection object 5 are calculated, and the material of the inspection object 5 is identified from this.

図３において、材質識別ステップＳ７は、厚さ特定ステップＳ７１、減弱係数算出ステップＳ７２、実効原子番号・電子密度算出ステップＳ７３、および材質識別ステップＳ７４からなる。
厚さ特定ステップＳ７１では、偽画像３２を除去した擬似断層像３１から、複数の方向の被検査物５の厚さｘを特定する。この特定は、擬似断層像３１から画像処理、又はマウス等を用いて容易にできる。
減弱係数算出ステップＳ７２では、２以上のエネルギー領域における入射Ｘ線７と透過Ｘ線８の強度と被検査物５の厚さｘから、各エネルギー領域Ｅ１，Ｅ２における２以上の減弱係数μ１，μ２を求める。
実効原子番号・電子密度算出ステップＳ７３では、光電効果、コンプトン効果及び減弱係数の関係から実効原子番号Ｚｅｆｆと電子密度ρｅを算出する。
材質識別ステップＳ７４では、実効原子番号Ｚｅｆｆと電子密度ρｅから被検査物の材質を決定する。 In FIG. 3, the material identification step S7 includes a thickness identification step S71, an attenuation coefficient calculation step S72, an effective atomic number / electron density calculation step S73, and a material identification step S74.
In the thickness specifying step S71, the thickness x of the inspection object 5 in a plurality of directions is specified from the pseudo tomographic image 31 from which the false image 32 is removed. This specification can be easily performed from the pseudo tomographic image 31 using image processing or a mouse.
In the attenuation coefficient calculation step S72, from the intensity of the incident X-ray 7 and the transmitted X-ray 8 in the two or more energy regions and the thickness x of the inspection object 5, two or more attenuation coefficients μ in the respective energy regions E 1 and E 2 are obtained. 1 and μ 2 are obtained.
In the effective atomic number / electron density calculation step S73, the effective atomic number Z eff and the electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient.
In the material identification step S74, the material of the object to be inspected is determined from the effective atomic number Z eff and the electron density ρ e .

上述した本発明の装置と方法によれば、搬送装置１２、Ｘ線照射装置１４およびＸ線計測装置１６により、被検査物５を内部に有する荷物６を搬送しながら、搬送方向に直交する複数の方向から、所定のエネルギー分布１を有する線状の入射Ｘ線７を、同時又は時間をずらして照射し、荷物６の複数の断面に対する複数方向の透過Ｘ線強度分布Ｉ１，Ｉ２を２以上のエネルギー領域Ｅ１，Ｅ２に弁別して計測し記憶するので、被検査物５を連続的に検査して、短時間に結果を得ることができる。 According to the above-described apparatus and method of the present invention, a plurality of devices orthogonal to the transport direction are transported by the transport device 12, the X-ray irradiation device 14, and the X-ray measurement device 16 while transporting the load 6 having the inspection object 5 therein. In this direction, a linear incident X-ray 7 having a predetermined energy distribution 1 is irradiated simultaneously or at different times, and transmission X-ray intensity distributions I 1 and I 2 in a plurality of directions with respect to a plurality of cross sections of the luggage 6 are obtained. since two or more energy region E 1, E 2 to measure to discriminate stores, the object to be inspected 5 continuously testing, results can be obtained short time.

また、擬似断層像作成手段１８、透過像作成手段１９および偽画像除去手段２０により、計測した各断面の擬似断層像３１をその断面に対する複数方向の透過Ｘ線強度分布から作成し、複数の方向に対する荷物の透過像３３を作成し、擬似断層像３１と透過像３３を組み合わせ、透過像３３による物体の有無情報を追加して擬似断層像に含まれる偽画像３２を除去するので、検査速度を落とさずに偽画像３２を除去して、擬似断層像３１の検出精度を高めることができる。   Further, the pseudo tomographic image 31 of each cross section measured by the pseudo tomographic image creating means 18, the transmission image creating means 19 and the pseudo image removing means 20 is created from the transmission X-ray intensity distributions in a plurality of directions with respect to the cross section, and a plurality of directions are obtained. The transmission image 33 of the baggage is created, the pseudo tomographic image 31 and the transmission image 33 are combined, and the presence / absence information of the object by the transmission image 33 is added to remove the false image 32 included in the pseudo tomographic image. The false image 32 can be removed without dropping and the detection accuracy of the pseudo tomographic image 31 can be improved.

さらに、識別演算装置２２により、偽画像３２を除去した擬似断層像３１内の被検査物５に関して、２以上のエネルギー領域Ｅ１，Ｅ２における入射Ｘ線７と透過Ｘ線８の強度から、被検査物５の実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物５の材質を識別するので、短時間にその材質を識別することができ、かつ予めＸ線の検出出力と対象物の厚みとの特性データを求める必要がない。 Furthermore, regarding the inspected object 5 in the pseudo tomographic image 31 from which the false image 32 has been removed by the identification arithmetic unit 22, from the intensity of the incident X-ray 7 and the transmitted X-ray 8 in the two or more energy regions E 1 and E 2 , Since the effective atomic number Z eff and the electron density ρ e of the inspection object 5 are calculated and the material of the inspection object 5 is identified from the effective atomic number Z eff , the material can be identified in a short time, and the X-ray detection output can be obtained in advance. There is no need to obtain characteristic data on the thickness of the object.

すなわち、本発明は、Ｘ線を用いて複数方向からの透過Ｘ線の強度（又は強度分布）とＸ線のエネルギー弁別によって取得した情報を利用して、物質を正確に識別することができる。   That is, according to the present invention, a substance can be accurately identified by using X-rays and using information acquired by intensity (or intensity distribution) of transmitted X-rays from a plurality of directions and energy discrimination of X-rays.

図５は、本発明による材質識別検査装置の第２実施形態を示す構成図である。この図は、図２のＺ方向から見た別の図である。この図において、本発明の材質識別検査装置１０は、図２と同様に、搬送装置１２、Ｘ線照射装置１４、及びＸ線計測装置１６と図示しない擬似断層像作成手段、透過像作成手段、偽画像除去手段及び識別演算装置を備える。図示しない擬似断層像作成手段、透過像作成手段、偽画像除去手段及び識別演算装置は、上述した第１実施形態における擬似断層像作成手段１８、透過像作成手段１９、偽画像除去手段２０及び識別演算装置２２と同一である。   FIG. 5 is a block diagram showing a second embodiment of the material identification inspection apparatus according to the present invention. This figure is another figure seen from the Z direction of FIG. In this figure, the material identification inspection apparatus 10 of the present invention is similar to FIG. 2 in that a conveying device 12, an X-ray irradiation device 14, and an X-ray measuring device 16, pseudo tomographic image creating means, transmission image creating means, not shown, A fake image removing unit and an identification calculation device are provided. The pseudo tomographic image creating means, the transmission image creating means, the false image removing means, and the identification computing device (not shown) are the pseudo tomographic image creating means 18, the transmission image creating means 19, the false image removing means 20 and the identification in the first embodiment described above. It is the same as the arithmetic unit 22.

この例において、Ｘ線照射装置１４は、荷物６を中心として互いに１２０°の周方向間隔で配置された３台のＸ線管１５ａ，１５ｂ，１５ｃであり、搬送方向に直交する同一断面内で被検査物５を内部に有する荷物６に対し所定のエネルギー分布１の入射Ｘ線７を線状かつ扇状に照射するようになっている。   In this example, the X-ray irradiation device 14 includes three X-ray tubes 15a, 15b, and 15c arranged at a circumferential interval of 120 ° around the baggage 6, and within the same cross section orthogonal to the transport direction. Incident X-rays 7 having a predetermined energy distribution 1 are irradiated linearly and in a fan-like manner on the luggage 6 having the inspection object 5 therein.

またこの例において、Ｘ線検出装置１６は、３台のＸ線管１５ａ，１５ｂ，１５ｃに対向するように互いに１２０°の周方向間隔で配置された３台の線状検出器１７ａ，１７ｂ，１７ｃであり、被検査物５を内部に有する荷物６を透過した線状のＸ線から２以上のエネルギー領域Ｅ１，Ｅ２の強度分布Ｉ１，Ｉ２を弁別して計測するようになっている。
第２実施形態では、同一の平面内に３組のＸ線照射装置１４とＸ線検出装置１６が配置されている点で、第１実施形態と相違する。その他の構成は第１実施形態と同様である。 In this example, the X-ray detection device 16 includes three linear detectors 17a, 17b, which are arranged at 120 ° circumferential intervals so as to face the three X-ray tubes 15a, 15b, 15c. a 17c, so as to measure and discriminate the intensity distribution I 1, I 2 of the specimen 5 at least two energy regions E from linear X-rays transmitted through cargo 61 included therein, E 2 Yes.
The second embodiment is different from the first embodiment in that three sets of the X-ray irradiation device 14 and the X-ray detection device 16 are arranged in the same plane. Other configurations are the same as those of the first embodiment.

上述した構成により、３台のＸ線管１５ａ，１５ｂ，１５ｃと３台の線状検出器１７ａ，１７ｂ，１７ｃが、被検査物５およびその容器６を同一平面内で囲むことにより、３つの照射方向から、所定のエネルギー分布１の入射Ｘ線７を、同時又は時間をずらして照射し、透過した透過Ｘ線８から２以上のエネルギー領域Ｅ１，Ｅ２のＸ線強度Ｉ１，Ｉ２を弁別して計測するので、第１実施形態と比較して、計測時間を短縮することができる。なおその他の効果は、第１実施形態と同様である。 With the above-described configuration, the three X-ray tubes 15a, 15b, and 15c and the three linear detectors 17a, 17b, and 17c surround the object 5 and its container 6 in the same plane, X-ray intensities I 1 and I of two or more energy regions E 1 and E 2 from the transmitted X-rays 8 which are irradiated at the same time or at different times from the irradiation direction and incident X-rays 7 having a predetermined energy distribution 1 are irradiated. Since 2 is discriminated and measured, the measurement time can be shortened as compared with the first embodiment. Other effects are the same as those of the first embodiment.

また、図５に示したＸ線照射装置１４とＸ線計測装置１６の構成を搬送方向（Ｚ方向）に直交する断面内で、周方向に任意の角度範囲で揺動させて、同一断面に対して、６方向以上の多数の照射方向から線状の入射Ｘ線７を照射し透過した透過Ｘ線８を計測してもよい。
さらに、図５に示したＸ線照射装置１４とＸ線計測装置１６の構成をＺ方向の異なる位置に周方向に角度をずらして複数設置して、同一断面に対して、６以上の多数の照射方向から線状の入射Ｘ線７を照射し透過した透過Ｘ線８を計測してもよい。
これらの手段によっても、第１実施形態と同様に、被検査物を連続的に検査して、短時間にその材質を識別することができ、かつ予めＸ線の検出出力と対象物の厚みとの特性データを求める必要がないという効果が得られる。 In addition, the configurations of the X-ray irradiation device 14 and the X-ray measurement device 16 shown in FIG. 5 are swung within an arbitrary angular range in the circumferential direction within the cross section orthogonal to the transport direction (Z direction), so that the same cross section is obtained. On the other hand, the transmitted X-rays 8 that are transmitted through the irradiation with the linear incident X-rays 7 from a plurality of irradiation directions of six or more directions may be measured.
Further, a plurality of configurations of the X-ray irradiation device 14 and the X-ray measurement device 16 shown in FIG. 5 are installed at different positions in the Z direction at different angles in the circumferential direction. You may measure the transmitted X-ray 8 which irradiated and irradiated the linear incident X-ray 7 from the irradiation direction.
Also by these means, as in the first embodiment, it is possible to inspect the inspection object continuously, identify the material in a short time, and to detect the X-ray detection output and the thickness of the object in advance. It is possible to obtain an effect that it is not necessary to obtain the characteristic data.

なお、本発明は、上述した実施形態に限定されず、本発明の要旨を逸脱しない範囲で種々に変更することができることは勿論である。   In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

本発明で使用するＸ線管とＸ線検出器のスペクトル図である。It is a spectrum figure of the X-ray tube and X-ray detector which are used by this invention. 本発明による材質識別検査装置の第１実施形態を示す構成図である。It is a block diagram which shows 1st Embodiment of the material identification inspection apparatus by this invention. 本発明の材質識別検査方法を示す全体フロー図である。It is a whole flowchart which shows the material identification inspection method of this invention. 本発明の方法の模式的説明図である。It is a typical explanatory view of the method of the present invention. 本発明による材質識別検査装置の第２実施形態を示す構成図である。It is a block diagram which shows 2nd Embodiment of the material identification inspection apparatus by this invention. 特許文献１の装置の模式図である。It is a schematic diagram of the apparatus of patent document 1. FIG. 特許文献３の装置の模式図である。It is a schematic diagram of the apparatus of patent document 3. FIG. 特許文献４の装置の模式図である。It is a schematic diagram of the apparatus of patent document 4.

符号の説明Explanation of symbols

１ 入射Ｘ線の強度分布、
２ 入射Ｘ線の検出強度分布、
３ 透過Ｘ線の検出強度分布、
５ 被検査物、６ 荷物、７ 入射Ｘ線、８ 透過Ｘ線、
１０ 材質識別検査装置、１２ 搬送装置、
１４ Ｘ線照射装置、１５ａ，１５ｂ，１５ｃ Ｘ線管、
１６ Ｘ線検出装置、１７ａ，１７ｂ，１７ｃ 線状検出器、
１８ 擬似断層像作成手段、１９ 透過像作成手段、
２０ 偽画像除去手段、２２ 識別演算装置、
２３ 入力装置、２４ 出力装置、２５ 記憶装置、
３１ 擬似断層像、３２ 偽画像、３３ 透過像 1 Incident X-ray intensity distribution,
2 Incident X-ray detection intensity distribution,
3 Detection intensity distribution of transmitted X-ray,
5 inspection object, 6 luggage, 7 incident X-ray, 8 transmitted X-ray,
10 material identification inspection device, 12 transport device,
14 X-ray irradiation device, 15a, 15b, 15c X-ray tube,
16 X-ray detectors, 17a, 17b, 17c linear detectors,
18 pseudo tomographic image creation means, 19 transmission image creation means,
20 fake image removal means, 22 identification calculation device,
23 input devices, 24 output devices, 25 storage devices,
31 pseudo tomographic image, 32 pseudo image, 33 transmission image

Claims (4)

被検査物を内部に有する荷物を搬送する搬送装置と、
該荷物の搬送方向に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線を、同時又は時間をずらして照射するＸ線照射装置と、
前記荷物の複数の断面に対する複数の照射方向のそれぞれについて、透過Ｘ線強度分布を２以上のエネルギー領域に弁別して計測し記憶するＸ線計測装置と、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各断面の擬似断層像を作成する擬似断層像作成手段と、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各照射方向の透過像を作成する透過像作成手段と、
前記擬似断層像と前記透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去する偽画像除去手段と、
偽画像を除去した前記擬似断層像内の被検査物に関して、２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度から、前記被検査物の実効原子番号と電子密度を算出し、これから被検査物の材質を識別する識別演算装置と、を備えたことを特徴とする材質識別検査装置。 A transport device for transporting a load having an inspection object inside;
An X-ray irradiation apparatus that irradiates linear incident X-rays having a predetermined energy distribution at the same time or at different times from a plurality of irradiation directions orthogonal to the load carrying direction;
And X-ray measuring device for each of the radiation directions, to measure and discriminate the transmitted X-ray intensity distribution into two or more energy area storage for a plurality of cross-section of the cargo,
A pseudo tomographic image creating means for creating a pseudo tomographic image of each cross section from a transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections;
A transmission image creating means for creating a transmission image in each irradiation direction from a transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections;
A false image removing unit that combines the pseudo tomographic image and the transmission image, and removes the false image included in the pseudo tomographic image from the presence / absence information of the object by the transmission image;
With respect to the inspection object in the pseudo tomographic image from which the false image has been removed, the effective atomic number and electron density of the inspection object are calculated from the intensities of incident X-rays and transmission X-rays in two or more energy regions, and from this, A material identification inspection device comprising: an identification operation device for identifying a material of an inspection object. 前記識別演算装置は、偽画像を除去した前記擬似断層像から、前記複数の照射方向の被検査物の厚さｘを特定し、
前記２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度と前記厚さから、各エネルギー領域における２以上の減弱係数μを求め、
光電効果、コンプトン効果及び減弱係数の関係から実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物の材質を識別する、ことを特徴とする請求項１に記載の材質識別検査装置。 The identification calculation device identifies the thickness x of the object to be inspected in the plurality of irradiation directions from the pseudo tomographic image from which the false image is removed,
From the intensity of incident X-rays and transmitted X-rays in the two or more energy regions and the thickness, obtain an attenuation coefficient μ of two or more in each energy region,
The material identification inspection apparatus according to claim 1, wherein an effective atomic number Z eff and an electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient, and the material of the object to be inspected is identified from the effective atomic number Z eff. . 被検査物を内部に有する荷物を搬送し、
該荷物の搬送方向に直交する複数の照射方向から、所定のエネルギー分布を有する線状の入射Ｘ線を、同時又は時間をずらして照射し、
前記荷物の複数の断面に対する複数の照射方向のそれぞれについて、透過Ｘ線強度分布を２以上のエネルギー領域に弁別して計測し記憶し、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各断面の擬似断層像を作成し、
前記複数の断面に対する複数の照射方向の透過Ｘ線強度分布から、前記各照射方向の透過像を作成し、
前記擬似断層像と前記透過像を組み合わせ、透過像による物体の有無情報から擬似断層像に含まれる偽画像を除去し、
偽画像を除去した前記擬似断層像内の被検査物に関して、２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度から、前記被検査物の実効原子番号と電子密度を算出し、これから被検査物の材質を識別する、ことを特徴とする材質識別検査方法。 Carrying luggage with the inspection object inside,
Irradiate linear incident X-rays having a predetermined energy distribution simultaneously or at different times from a plurality of irradiation directions orthogonal to the carrying direction of the luggage,
For each of a plurality of irradiation directions for a plurality of cross sections of the luggage , the transmitted X-ray intensity distribution is measured and stored in two or more energy regions,
From the transmission X-ray intensity distribution in a plurality of irradiation directions with respect to the plurality of cross sections, a pseudo tomographic image of each cross section is created,
From the transmission X-ray intensity distribution in a plurality of irradiation directions for the plurality of cross-sections, create a transmission image in each irradiation direction,
Combining the pseudo tomogram and the transmission image, removing the false image included in the pseudo tomogram from the presence / absence information of the object by the transmission image,
With respect to the inspection object in the pseudo tomographic image from which the false image has been removed, the effective atomic number and electron density of the inspection object are calculated from the intensities of incident X-rays and transmission X-rays in two or more energy regions, and from this, A material identification inspection method characterized by identifying a material of an inspection object. 偽画像を除去した前記擬似断層像から、前記複数の照射方向の被検査物の厚さｘを特定し、
前記２以上のエネルギー領域における入射Ｘ線と透過Ｘ線の強度と前記厚さから、各エネルギー領域における２以上の減弱係数μを求め、
光電効果、コンプトン効果及び減弱係数の関係から実効原子番号Ｚｅｆｆと電子密度ρｅを算出し、これから被検査物の材質を識別する、ことを特徴とする請求項３に記載の材質識別検査方法。 From the pseudo tomographic image from which the false image is removed, the thickness x of the inspection object in the plurality of irradiation directions is specified,
From the intensity of incident X-rays and transmitted X-rays in the two or more energy regions and the thickness, obtain an attenuation coefficient μ of two or more in each energy region,
4. The material identification inspection method according to claim 3, wherein the effective atomic number Z eff and the electron density ρ e are calculated from the relationship between the photoelectric effect, the Compton effect, and the attenuation coefficient, and the material of the inspection object is identified from the effective atomic number Z eff. .
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