JP2017200522A

JP2017200522A - Radiation imaging device and radiation imaging system

Info

Publication number: JP2017200522A
Application number: JP2016092802A
Authority: JP
Inventors: 長野　和美; Kazumi Nagano; 和美長野; 野村　慶一; Keiichi Nomura; 慶一野村; 尚志郎猿田; Hisashiro Saruta
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2016-05-02
Filing date: 2016-05-02
Publication date: 2017-11-09

Abstract

PROBLEM TO BE SOLVED: To provide an advantageous technique which allows a radiation imaging device using two imaging panels to acquire an energy subtraction image by a single radiation exposure.SOLUTION: The present invention relates to a radiation imaging device, comprising: a first imaging panel provided with a first pixel array including a plurality of first pixels arranged in matrix to output signals in response to radiation or light; and a second imaging panel provided with a second pixel array including a plurality of second pixels arranged in matrix to output signals in response to radiation or light. The first imaging panel is disposed first and the second imaging panel is disposed next from the side of the incidence plane for irradiation with radiation such that the first imaging array and the second imaging array are overlapped with each other. The aperture ratio of the second pixels is smaller than the aperture radio of the first pixels.SELECTED DRAWING: Figure 1

Description

本発明は、放射線撮像装置及び放射線撮像システムに関する。 The present invention relates to a radiation imaging apparatus and a radiation imaging system.

医療画像診断や非破壊検査に放射線撮像装置が広く利用されている。この放射線撮像装置を用いて、被写体に対してエネルギ成分が異なる放射線の放射線画像を複数取得し、取得した放射線画像の差分から、特定の被写体部分を分離又は強調したエネルギサブトラクション画像を取得する方法が知られている。特許文献１〜３には、エネルギサブトラクション画像を取得するために、２つの撮像パネルを用いて、被写体に対して１回の放射線照射（ワンショット法）で２つの異なるエネルギ成分の放射線の放射線画像を記録する放射線撮像装置が提案されている。 Radiation imaging apparatuses are widely used for medical image diagnosis and nondestructive inspection. A method of acquiring a plurality of radiation images of radiation having different energy components with respect to a subject using the radiation imaging apparatus and acquiring an energy subtraction image in which a specific subject portion is separated or emphasized from a difference between the acquired radiation images. Are known. In Patent Documents 1 to 3, radiation images of radiation of two different energy components are obtained with one radiation irradiation (one-shot method) on a subject using two imaging panels in order to obtain an energy subtraction image. A radiation imaging apparatus for recording the above has been proposed.

特開平５−２０８０００号公報JP-A-5-208000 特開２００１−２４９１８２号公報JP 2001-249182 A 特開２０００−２９８１９８号公報JP 2000-298198 A

２つの撮像パネルを重ねて用いる場合、それぞれの撮像パネルと放射線源との間の距離が異なるため、放射線は、放射線源から遠い側の撮像パネルにおいて、放射線源に近い側の撮像パネルよりも広がって検出される。同じ構成の撮像パネルを用いて、それぞれ同じ位置に配された画素から出力される信号の差分からエネルギサブトラクション画像を生成する場合、遠い側の撮像パネルの画素は、近い側の撮像パネルの同じ位置の画素よりも内側の画素を透過した放射線を検出しうる。放射線源から遠い側の撮像パネルの画素が、近い側の撮像パネルの同じ位置の画素以外を透過した放射線を検出することに起因するノイズによって、エネルギサブトラクション画像の画質が低下しうる。 When two imaging panels are used in an overlapping manner, the distance between each imaging panel and the radiation source is different, so that radiation spreads more in the imaging panel far from the radiation source than in the imaging panel closer to the radiation source. Detected. When an energy subtraction image is generated from the difference between signals output from pixels arranged at the same position using imaging panels having the same configuration, the pixels on the far side imaging panel are located at the same positions on the near side imaging panel. It is possible to detect radiation that has passed through a pixel inside the pixel. The image quality of the energy subtraction image may be deteriorated by noise caused by the detection of the radiation transmitted from the pixels on the side farther from the radiation source than the pixels at the same position on the near side imaging panel.

本発明は、放射線撮像装置において、２つの撮像パネルを用い、１回の放射線の照射でエネルギサブトラクション画像を取得するために有利な技術を提供することを目的とする。 An object of the present invention is to provide an advantageous technique for acquiring an energy subtraction image by one radiation irradiation using two imaging panels in a radiation imaging apparatus.

上記課題に鑑みて、本発明の実施形態に係る放射線撮像装置は、行列状に複数配された放射線又は光に応じた信号を出力するための第１の画素を含む第１の画素アレイを備えた第１の撮像パネルと、行列状に複数配された放射線又は光に応じた信号を出力するための第２の画素を含む第２の画素アレイを備えた第２の撮像パネルと、を含み、第１の画素アレイ及び第２の画素アレイが互いに重なるように、放射線を照射するための入射面の側から、第１の撮像パネル、第２の撮像パネルの順に重ねて配された放射線撮像装置であって、第１の画素の開口率よりも第２の画素の開口率が小さいことを特徴とする。 In view of the above problems, a radiation imaging apparatus according to an embodiment of the present invention includes a first pixel array including a first pixel for outputting a signal corresponding to radiation or light arranged in a matrix. A first imaging panel, and a second imaging panel including a second pixel array including a second pixel for outputting a signal corresponding to radiation or light arranged in a matrix. Radiation imaging in which the first imaging panel and the second imaging panel are stacked in this order from the incident surface side for irradiating radiation so that the first pixel array and the second pixel array overlap each other An apparatus is characterized in that the aperture ratio of the second pixel is smaller than the aperture ratio of the first pixel.

上記手段によって、放射線撮像装置において、２つの撮像パネルを用い、１回の放射線の照射でエネルギサブトラクション画像を取得するために有利な技術が提供される。 The above means provides an advantageous technique for acquiring an energy subtraction image in a radiation imaging apparatus using two imaging panels with a single irradiation of radiation.

本発明の実施形態に係る放射線撮像装置の構成例を示す断面図。Sectional drawing which shows the structural example of the radiation imaging device which concerns on embodiment of this invention. 図１の放射線撮像装置の断面の拡大図及び平面図。The enlarged view and top view of the cross section of the radiation imaging device of FIG. 図１の放射線撮像装置の断面の拡大図及び平面図。The enlarged view and top view of the cross section of the radiation imaging device of FIG. 図１の放射線撮像装置の変形例を示す断面図。Sectional drawing which shows the modification of the radiation imaging device of FIG. 図１の放射線撮像装置に入射する放射線を示す断面図。Sectional drawing which shows the radiation which injects into the radiation imaging device of FIG. 本発明に係る放射線撮像装置を用いた放射線撮像システムの構成例を説明する図。The figure explaining the structural example of the radiation imaging system using the radiation imaging device which concerns on this invention.

以下、本発明に係る放射線撮像装置の具体的な実施形態及び実施例を、添付図面を参照して説明する。なお、以下の説明及び図面において、複数の図面に渡って共通の構成については共通の符号を付している。そのため、複数の図面を相互に参照して共通する構成を説明し、共通の符号を付した構成については適宜説明を省略する。なお、本発明における放射線には、放射線崩壊によって放出される粒子（光子を含む）の作るビームであるα線、β線、γ線などの他に、同程度以上のエネルギを有するビーム、例えばＸ線や粒子線、宇宙線なども含みうる。 Hereinafter, specific embodiments and examples of a radiation imaging apparatus according to the present invention will be described with reference to the accompanying drawings. Note that, in the following description and drawings, common reference numerals are given to common configurations over a plurality of drawings. Therefore, a common configuration is described with reference to a plurality of drawings, and a description of a configuration with a common reference numeral is omitted as appropriate. The radiation in the present invention includes a beam having energy of the same degree or more, such as X-rays, β-rays, γ-rays, etc., which are beams formed by particles (including photons) emitted by radiation decay, such as X It can also include rays, particle rays, and cosmic rays.

＜実施形態＞
図１〜５を参照して、本発明の実施形態による放射線撮像装置の構造について説明する。図１は、本発明の実施形態における放射線撮像装置１００の構成例を示す断面図である。図１に示される放射線撮像装置１００は、１つの筐体１０８の中に放射線を検出するための撮像パネル１０１ａ、１０１ｂを含む。放射線撮像装置１００は、２つの撮像パネル１０１ａ、１０１ｂを備えることによって、被写体に対して１回の放射線の照射（ワンショット法）でエネルギサブトラクション画像の取得が可能な構成を有する。このため、筐体１０８の放射線１１０を照射するための入射面１１１に対する正射影において、撮像パネル１０１、１０２は互いに重なるように配される。また、本実施形態の各図に示す構成において、２つの撮像パネル１０１ａ、１０１ｂのうち、撮像パネル１０１ａの方が、撮像パネル１０１ｂよりも入射面１１１に近い放射線の入射する側に配される。 <Embodiment>
With reference to FIGS. 1-5, the structure of the radiation imaging device by embodiment of this invention is demonstrated. FIG. 1 is a cross-sectional view illustrating a configuration example of a radiation imaging apparatus 100 according to an embodiment of the present invention. A radiation imaging apparatus 100 shown in FIG. 1 includes imaging panels 101 a and 101 b for detecting radiation in one housing 108. The radiation imaging apparatus 100 includes two imaging panels 101a and 101b so that an energy subtraction image can be acquired by one-time radiation irradiation (one-shot method) on a subject. For this reason, the imaging panels 101 and 102 are arranged so as to overlap each other in the orthogonal projection with respect to the incident surface 111 for irradiating the radiation 110 of the housing 108. In the configuration shown in each drawing of this embodiment, of the two imaging panels 101a and 101b, the imaging panel 101a is arranged on the radiation incident side closer to the incident surface 111 than the imaging panel 101b.

撮像パネル１０１ａ、１０１ｂは、それぞれ基板１０２ａ、１０２ｂ、基板１０２ａ、１０２ｂの上に配された画素アレイ１０３ａ、１０３ｂ、及び、画素アレイ１０３ａ、１０３ｂの上に配されたシンチレータ１０４ａ、１０４ｂを含む。また、撮像パネル１０１ａ、１０１ｂは、シンチレータ１０４ａ、１０４ｂの上に、保護層１０５ａ、１０５ｂを含む。２つの撮像パネル１０１ａ、１０１ｂは、結合層１０７によって、互いに固定されうる。 The imaging panels 101a and 101b include substrates 102a and 102b, pixel arrays 103a and 103b disposed on the substrates 102a and 102b, and scintillators 104a and 104b disposed on the pixel arrays 103a and 103b, respectively. The imaging panels 101a and 101b include protective layers 105a and 105b on the scintillators 104a and 104b. The two imaging panels 101 a and 101 b can be fixed to each other by the coupling layer 107.

画素アレイ１０３ａ、１０３ｂには、画素が行列状に複数配される。それぞれの画素は、入射した放射線に応じた信号を出力するための変換部を有する。画素アレイ１０３ａに配された画素には変換部１０６ａが、画素アレイ１０３ｂに配された画素には変換部１０６ｂが、それぞれ配される。また、それぞれの画素は、変換部１０６ａ、１０６ｂで生成した信号を適切なタイミングで読み出すためのスイッチ素子を有しうる。 A plurality of pixels are arranged in a matrix in the pixel arrays 103a and 103b. Each pixel has a conversion unit for outputting a signal corresponding to the incident radiation. The conversion unit 106a is arranged for the pixels arranged in the pixel array 103a, and the conversion unit 106b is arranged for the pixels arranged in the pixel array 103b. Each pixel may have a switch element for reading out signals generated by the conversion units 106a and 106b at appropriate timing.

本実施形態において、撮像パネル１０１ａ、１０１ｂは、シンチレータ１０４ａ、１０４ｂで放射線から変換された光を、画素アレイ１０３ａ、１０３ｂに配されたそれぞれの画素の変換部１０６ａ、１０６ｂによって信号に変換する間接型の撮像パネルを用いる。例えば、基板１０２ａ、１０２ｂとしてガラス基板などの絶縁性基板を用い、その上に形成されたシリコンなどの半導体層に、変換部１０６ａ、１０６ｂやスイッチ素子をそれぞれ有する画素が配された画素アレイ１０３ａ、１０３ｂを形成する。変換部１０６ａ、１０６ｂは、半導体領域に形成されたｐｎ、ｐｉｎ、ＭＩＳ型などの光電変換素子でありうる。また、スイッチ素子は、半導体領域に形成された薄膜トランジスタ（ＴＦＴ）などでありうる。変換部１０６ａ、１０６ｂ及びスイッチ素子の形成された画素アレイ１０３ａ、１０３ｂは、アレイ保護層や撮像パネル１０１ａ、１０１ｂの外部に信号を出力するための接続パッド（不図示）を更に含みうる。アレイ保護層は、変換部１０６ａ、１０６ｂをそれぞれ覆うように形成され、例えば、ＳｉＮ、ＴｉＯ_２、ＬｉＦ、Ａｌ_２Ｏ_３、ＭｇＯなどが用いられる。また、ポリフェニレンサルファイド樹脂、フッ素樹脂、ポリエーテルエーテルケトン樹脂、液晶ポリマー、ポリエーテルニトリル樹脂、ポリスルホン樹脂、ポリエーテルサルホン樹脂、ポリアリレート樹脂、ポリアミドイミド樹脂、ポリエーテルイミド樹脂、ポリイミド樹脂、エポキシ樹脂、シリコーン樹脂などを用いてもよい。ただし、アレイ保護層はシンチレータ１０４ａ、１０４ｂによって変換された光の波長について、高い透過率を有する材料で構成されうる。 In this embodiment, the imaging panels 101a and 101b are indirect types that convert light converted from radiation by the scintillators 104a and 104b into signals by the conversion units 106a and 106b of the respective pixels arranged in the pixel arrays 103a and 103b. The imaging panel is used. For example, a pixel array 103a, in which an insulating substrate such as a glass substrate is used as the substrates 102a and 102b, and pixels having conversion units 106a and 106b and switching elements are arranged on a semiconductor layer such as silicon formed thereon, 103b is formed. The conversion units 106a and 106b can be pn, pin, MIS type photoelectric conversion elements formed in the semiconductor region. The switch element can be a thin film transistor (TFT) formed in the semiconductor region. The pixel arrays 103a and 103b in which the conversion units 106a and 106b and the switch elements are formed may further include a connection pad (not shown) for outputting signals to the outside of the array protective layer and the imaging panels 101a and 101b. The array protective layer is formed so as to cover the conversion units 106a and 106b, and, for example, SiN, TiO ₂ , LiF, Al ₂ O ₃ , MgO, or the like is used. Also, polyphenylene sulfide resin, fluorine resin, polyether ether ketone resin, liquid crystal polymer, polyether nitrile resin, polysulfone resin, polyether sulfone resin, polyarylate resin, polyamide imide resin, polyether imide resin, polyimide resin, epoxy resin Silicone resin or the like may be used. However, the array protective layer can be made of a material having a high transmittance with respect to the wavelength of the light converted by the scintillators 104a and 104b.

本実施形態では、入射する放射線１１０をシンチレータ１０４ａ、１０４ｂで光に変換し、変換された光を検出する間接型の撮像パネル１０１ａ、１０１ｂを用いるが、これに限られることはない。撮像パネル１０１ａ、１０２ｂが、入射した放射線１１０を直接、電気信号に変換する変換素子を用いた直接型の撮像パネルであってもよい。この場合、画素アレイ１０３ａ、１０３ｂの変換部１０６ａ、１０６ｂにはアモルファスセレンなどの材料が用いられうる。 In this embodiment, the indirect imaging panels 101a and 101b that convert the incident radiation 110 into light by the scintillators 104a and 104b and detect the converted light are used, but the present invention is not limited to this. The imaging panels 101a and 102b may be direct imaging panels using conversion elements that directly convert incident radiation 110 into electrical signals. In this case, a material such as amorphous selenium can be used for the conversion units 106a and 106b of the pixel arrays 103a and 103b.

シンチレータ１０４ａ、１０４ｂに、柱状結晶構造を有するシンチレータが用いられてもよい。また、シンチレータ１０４ａ、１０４ｂに、粒子状のシンチレータと粒子状のシンチレータを固定するバインダとを含む構造が用いられてもよい。柱状結晶を形成するシンチレータの材料として、ハロゲン化アルカリを主成分とする材料が用いられうる。例えば、ＣｓＩ：Ｔｌ、ＣｓＩ：Ｎａ、ＣｓＢｒ：Ｔｌ、ＮａＩ：Ｔｌ、ＬｉＩ：Ｅｕ、ＫＩ：Ｔｌなどが、シンチレータ１０４ａ、１０４ｂとして用いられうる。例えば、ＣｓＩ：Ｔｌをシンチレータ１０４ａ、１０４ｂとして用いる場合、ＣｓＩとＴｌＩとを同時に蒸着することによってシンチレータ１０４ａ、１０４ｂを形成できる。柱状結晶構造を有するシンチレータは、シンチレータで放射線から変換された光が柱状結晶内を伝搬しやすいため、光散乱が抑制され、高い解像度を得ることができる。また、粒子状のシンチレータの材料を用いる場合、耐湿性、発光効率、熱プロセス耐性、残光性の観点から、一般式Ｍｅ_２Ｏ_２Ｓ：Ｒｅで示される金属酸硫化物が用いられうる。例えば、Ｍｅは、Ｌａ、Ｙ、Ｇｄの何れかを１つ以上を含み、Ｒｅは、Ｔｂ、Ｓｍ、Ｅｕ、Ｃｅ、Ｐｒ、Ｔｍの何れか１つ以上を含む。例えば、微量のテルビウムが添加された酸硫化ガドリニウムが、シンチレータ１０４ａ、１０４ｂに用いられうる。 A scintillator having a columnar crystal structure may be used for the scintillators 104a and 104b. Further, a structure including a particulate scintillator and a binder for fixing the particulate scintillator may be used for the scintillators 104a and 104b. As a material of the scintillator for forming the columnar crystal, a material mainly composed of an alkali halide can be used. For example, CsI: Tl, CsI: Na, CsBr: Tl, NaI: Tl, LiI: Eu, KI: Tl, etc. can be used as the scintillators 104a and 104b. For example, when CsI: Tl is used as the scintillators 104a and 104b, the scintillators 104a and 104b can be formed by simultaneously vapor-depositing CsI and TlI. In the scintillator having a columnar crystal structure, since light converted from radiation by the scintillator easily propagates in the columnar crystal, light scattering is suppressed and high resolution can be obtained. In the case of using a particulate scintillator material, a metal oxysulfide represented by the general formula Me ₂ O ₂ S: Re can be used from the viewpoints of moisture resistance, light emission efficiency, thermal process resistance, and afterglow. For example, Me includes at least one of La, Y, and Gd, and Re includes at least one of Tb, Sm, Eu, Ce, Pr, and Tm. For example, gadolinium oxysulfide to which a small amount of terbium is added can be used for the scintillators 104a and 104b.

シンチレータ１０４ａ、１０４ｂは、互いに同じ材料によって形成されてもよいし、それぞれに異なる材料を用いて形成してもよい。シンチレータ１０４ａ、１０４ｂに同じ材料を用いることによって、放射線撮像装置１００に用いる材料の種類を抑制し、放射線撮像装置１００の製造コストを抑制することができる。また、シンチレータ１０４ａ、１０４ｂに、それぞれ異なる材料を用いることによって、撮像パネル１０１ａ、１０１ｂのそれぞれに適した材料を使用することができる。 The scintillators 104a and 104b may be formed of the same material, or may be formed of different materials. By using the same material for the scintillators 104a and 104b, the type of material used for the radiation imaging apparatus 100 can be suppressed, and the manufacturing cost of the radiation imaging apparatus 100 can be suppressed. In addition, by using different materials for the scintillators 104a and 104b, materials suitable for the imaging panels 101a and 101b can be used.

また、シンチレータ１０４ａ、１０４ｂを形成する方法として、画素アレイ１０３ａ、１０３ｂ上に直接、蒸着してもよいし、印刷形成してもよい。また、予め基台上に蒸着や印刷によってシンチレータ１０４ａ、１０４ｂを形成し、粘着剤などの結合部材を介して画素アレイ１０３ａ、１０３ｂと貼り合わせてもよく、シンチレータ１０４ａ、１０４ｂを形成する方法に特に制限はない。 Further, as a method of forming the scintillators 104a and 104b, vapor deposition may be directly performed on the pixel arrays 103a and 103b, or printing may be performed. In addition, the scintillators 104a and 104b may be formed on the base in advance by vapor deposition or printing, and may be bonded to the pixel arrays 103a and 103b via a bonding member such as an adhesive, and the scintillators 104a and 104b are particularly formed. There is no limit.

保護層１０５ａ、１０５ｂは、シンチレータ１０４ａ、１０４ｂを大気中の水分などから保護しうる。また、保護層１０５ａ、１０５ｂは、シンチレータ１０４ａ、１０４ｂで生成された光のうち画素アレイ１０３ａ、１０３ｂと反対側に進む光を、画素アレイ１０３ａ、１０３ｂに反射する反射層としての機能を有していてもよい。画素アレイ１０３ａ、１０３ｂと反対側に進む光を反射することによって、保護層１０５ａ、１０５ｂは、放射線撮像装置１００の感度を向上させうる。また、保護層１０５ａ、１０５ｂは、シンチレータ１０４ａ、１０４ｂで発生する光以外の光、例えば外部光が、画素アレイ１０３ａ、１０３ｂに入射することを抑制する機能も備えうる。また、保護層１０５ａ、１０５ｂは、シンチレータ１０４ａで発生した光が画素アレイ１０３ｂで検出されること、シンチレータ１０４ｂで発生した光が画素アレイ１０３ａで検出されることを、それぞれ抑制しうる。さらに、保護層１０５ａ、１０５ｂは、シンチレータ１０４ａ、１０４ｂの保護だけでなく、電磁シールドとして機能してもよい。保護層１０５ａ、１０５ｂには、例えば金属箔や金属薄膜で構成されうる。金属箔や金属薄膜で構成される保護層１０５ａ、１０５ｂは、１μｍ以上かつ１００μｍ以下程度の厚さを有しうる。保護層１０５ａ、１０５ｂの厚さが１μｍよりも薄い場合、保護層１０５ａ、１０５ｂの形成時にピンホール欠陥が発生しやすく耐湿性が低下する場合や、また、遮光性に劣る場合がある。一方、保護層１０５ａ、１０５ｂの厚さが１００μｍよりも厚い場合、保護層１０５ａ、１０５ｂでの放射線の吸収量が大きくなり、得られる放射線画像の画質が劣化する可能性がある。保護層１０５ａ、１０５ｂの材料として、例えばアルミニウム、金、銀、銅などの金属材料やその合金が用いられうる。アルミニウムは、放射線透過性が高いため、保護層１０５ａ、１０５ｂの材料として用いられうる。 The protective layers 105a and 105b can protect the scintillators 104a and 104b from moisture in the atmosphere. In addition, the protective layers 105a and 105b have a function as a reflection layer that reflects the light generated by the scintillators 104a and 104b to the opposite side of the pixel arrays 103a and 103b to the pixel arrays 103a and 103b. May be. The reflective layers 105a and 105b can improve the sensitivity of the radiation imaging apparatus 100 by reflecting the light traveling to the opposite side of the pixel arrays 103a and 103b. The protective layers 105a and 105b can also have a function of suppressing light other than light generated by the scintillators 104a and 104b, for example, external light, from entering the pixel arrays 103a and 103b. Further, the protective layers 105a and 105b can suppress the detection of the light generated by the scintillator 104a by the pixel array 103b and the detection of the light generated by the scintillator 104b by the pixel array 103a, respectively. Furthermore, the protective layers 105a and 105b may function as an electromagnetic shield as well as protect the scintillators 104a and 104b. The protective layers 105a and 105b can be made of, for example, a metal foil or a metal thin film. The protective layers 105a and 105b made of metal foil or metal thin film can have a thickness of about 1 μm to about 100 μm. When the thickness of the protective layers 105a and 105b is less than 1 μm, pinhole defects are likely to occur during the formation of the protective layers 105a and 105b, and the moisture resistance may be lowered, or the light shielding property may be poor. On the other hand, when the thickness of the protective layers 105a and 105b is greater than 100 μm, the amount of radiation absorbed by the protective layers 105a and 105b increases, and the image quality of the obtained radiographic image may deteriorate. As a material of the protective layers 105a and 105b, for example, a metal material such as aluminum, gold, silver, copper, or an alloy thereof can be used. Aluminum can be used as a material for the protective layers 105a and 105b because it has high radiation transparency.

保護層１０５ａ、１０５ｂに金属箔や金属薄膜を用いた場合、金属箔や金属薄膜の耐擦傷性を向上させるためにポリエチレンテレフタレート（ＰＥＴ）などの材料を用いた樹脂層を最外層に形成してもよい。また、図１に示す構成では、保護層１０５ａ、１０５ｂはシンチレータ１０４ａ、１０４ｂの上に配されているが、遮光性や電磁シールド性を向上するために、撮像パネル１０１ａ、１０１ｂ全体を覆っていてもよい。 When a metal foil or metal thin film is used for the protective layers 105a and 105b, a resin layer using a material such as polyethylene terephthalate (PET) is formed on the outermost layer in order to improve the scratch resistance of the metal foil or metal thin film. Also good. In the configuration shown in FIG. 1, the protective layers 105a and 105b are disposed on the scintillators 104a and 104b, but cover the entire imaging panels 101a and 101b in order to improve light shielding properties and electromagnetic shielding properties. Also good.

次に、図２を用いて画素アレイ１０３ａ、１０３ｂに配された画素がそれぞれ有する変換部１０６ａ、１０６ｂの配置について説明する。図２（ａ）は、図１に示す放射線撮像装置１００のうち撮像パネル１０１ａ、１０１ｂの画素２０１ａ、２０１ｂの拡大図を示す。図２（ｂ）は、入射面１１１に対する正射影における、撮像パネル１０１ａ、１０１ｂのそれぞれの画素２０１ａ、２０１ｂに配された変換部１０６ａ、１０６ｂの配置を示す平面図である。 Next, the arrangement of the conversion units 106a and 106b included in the pixels arranged in the pixel arrays 103a and 103b will be described with reference to FIG. FIG. 2A shows an enlarged view of the pixels 201a and 201b of the imaging panels 101a and 101b in the radiation imaging apparatus 100 shown in FIG. FIG. 2B is a plan view showing the arrangement of the conversion units 106a and 106b arranged in the respective pixels 201a and 201b of the imaging panels 101a and 101b in the orthogonal projection with respect to the incident surface 111. FIG.

本実施形態において、撮像パネル１０１ａ、１０１ｂに配される各画素２０１ａ、２０１ｂの変換部１０６ａ、１０６ｂは、入射面に対する正射影において、互いに重なる位置に配される。また、放射線の入射する側から遠い撮像パネル１０１ｂの画素アレイ１０３ｂに配された画素２０１ｂが有する変換部１０６ｂは、放射線の入射する側の撮像パネル１０１ａの画素アレイ１０３ａに配された画素２０１ａが有する変換部１０６ａよりも面積が小さい。画素アレイ１０３ａの画素２０１ａに配された変換部１０６ａには、それぞれ相対する位置に画素アレイ１０３ｂの画素２０１ｂに配された変換部１０６ｂが存在する。このため、撮像パネル１０１ａの画素アレイ１０３ａに含まれる画素２０１ａ及び変換部１０６ａの数と、撮像パネル１０１ｂの画素アレイ１０３ｂに含まれる画素２０１ｂ及び変換部１０６ｂの数とが同じであってもよい。 In the present embodiment, the conversion units 106a and 106b of the pixels 201a and 201b arranged on the imaging panels 101a and 101b are arranged at positions that overlap each other in the orthogonal projection with respect to the incident surface. Further, the conversion unit 106b included in the pixel 201b arranged in the pixel array 103b of the imaging panel 101b far from the radiation incident side has the pixel 201a arranged in the pixel array 103a of the imaging panel 101a on the radiation incident side. The area is smaller than that of the conversion unit 106a. In the conversion unit 106a arranged in the pixel 201a of the pixel array 103a, the conversion unit 106b arranged in the pixel 201b of the pixel array 103b is present at a position opposite to each other. For this reason, the number of pixels 201a and conversion units 106a included in the pixel array 103a of the imaging panel 101a may be the same as the number of pixels 201b and conversion units 106b included in the pixel array 103b of the imaging panel 101b.

２つの撮像パネルを重ねて用いる場合、それぞれの撮像パネルと放射線源との間の距離が異なる。このため、放射線源に近い側の撮像パネル１０１ａよりも放射線源から遠い側の撮像パネル１０１ｂで、撮像パネル１０１ａ、１０１ｂの中心から外縁側に向かって放射線が広がって検出される。換言すると、撮像パネル１０１ａ、１０１ｂの外周側では、放射線１１０は、撮像パネル１０１ａ、１０１ｂに対して斜めに入射しうる。図５（ａ）に示すように、撮像パネル１０１ａ、１０１ｂの画素アレイ１０３ａ、１０３ｂに同じ面積を有する変換部１０６ａ、１０６ｂを用いた場合を考える。この場合、画素アレイ１０３ｂの外周側に配された画素２０１ｂが有する変換部１０６ｂは、画素アレイ１０３ａの互いに重なる位置に配された画素２０１ａよりも中心側の画素２０１ａを透過した放射線を検出しうる。このため、それぞれ相対する位置に配された変換部１０６ａ、１０６ｂから出力される信号の差分からエネルギサブトラクション画像を生成する場合、互いに重なる位置の画素以外を透過した放射線を検出することに起因するノイズが発生しうる。このため、エネルギサブトラクション画像の画質が低下しうる。 When two imaging panels are used in an overlapping manner, the distance between each imaging panel and the radiation source is different. For this reason, radiation is spread and detected from the center of the imaging panels 101a and 101b toward the outer edge side by the imaging panel 101b farther from the radiation source than the imaging panel 101a closer to the radiation source. In other words, on the outer peripheral side of the imaging panels 101a and 101b, the radiation 110 can enter the imaging panels 101a and 101b obliquely. As shown in FIG. 5A, consider a case where conversion units 106a and 106b having the same area are used for the pixel arrays 103a and 103b of the imaging panels 101a and 101b. In this case, the conversion unit 106b included in the pixel 201b disposed on the outer peripheral side of the pixel array 103b can detect radiation that has passed through the pixel 201a that is closer to the center than the pixels 201a disposed in the pixel array 103a. . For this reason, when an energy subtraction image is generated from the difference between signals output from the conversion units 106a and 106b arranged at opposite positions, noise caused by detecting radiation transmitted through pixels other than the overlapping pixels. Can occur. For this reason, the image quality of the energy subtraction image can be lowered.

一方、本実施形態において、放射線の入射する側から遠い撮像パネル１０１ｂの各画素２０１ｂに配される変換部１０６ｂは、放射線の入射する側の撮像パネル１０１ａの各画素２０１ａに配される変換部１０６ａよりも面積が小さい。このため、図５（ｂ）に示すように、放射線源から遠い撮像パネル１０１ｂの画素２０１ｂに配された変換部１０６ｂは、入射側の撮像パネル１０１ａの相対する画素２０１ａに近接する画素２０１ａの変換部１０６ａを通過した放射線を検出しにくくなる。換言すると、撮像パネル１０１ｂの画素２０１ｂに配された変換部１０６ｂは、入射側の撮像パネル１０１ａの相対する画素２０１ａの変換部１０６ａを通過した放射線のみを検出しやすくなる。これによって、撮像パネル１０１ａと撮像パネル１０１ｂとで、相対する互いに重なる位置の画素以外を透過した放射線を検出することに起因するノイズ軽減し、得られるエネルギサブトラクション画像の空間分解能を向上することが可能となる。 On the other hand, in this embodiment, the conversion unit 106b arranged in each pixel 201b of the imaging panel 101b far from the radiation incident side is the conversion unit 106a arranged in each pixel 201a of the imaging panel 101a on the radiation incidence side. Is smaller than the area. Therefore, as shown in FIG. 5B, the conversion unit 106b disposed in the pixel 201b of the imaging panel 101b far from the radiation source converts the pixel 201a adjacent to the opposing pixel 201a of the incident-side imaging panel 101a. It becomes difficult to detect the radiation that has passed through the portion 106a. In other words, the conversion unit 106b disposed in the pixel 201b of the imaging panel 101b can easily detect only the radiation that has passed through the conversion unit 106a of the opposing pixel 201a of the incident-side imaging panel 101a. Thereby, the imaging panel 101a and the imaging panel 101b can reduce noise caused by detecting radiation that has passed through other than the mutually overlapping pixels, and can improve the spatial resolution of the obtained energy subtraction image. It becomes.

図２（ａ）、（ｂ）に示すように、撮像パネル１０１ａ、１０１ｂの全体に渡って、画素２０１ａが有する変換部１０６ａの中心と、相対して配された画素２０１ｂが有する変換部１０６ｂの中心とが、互いに重なる位置に配されてもよい。ここで、変換部１０６ａ、１０６ｂの中心とは、入射面１１１に対する正射影において、変換部１０６ａ、１０６ｂの形状の幾何学的重心の位置であってもよい。また、変換部１０６ａ、１０６ｂが矩形の場合、対角線の交点であってもよい。また、変換部１０６ａの中心と変換部１０６ｂの中心とが、それぞれの変換部１０６ａ、１０６ｂの並ぶピッチの長さの５％以下程度の長さ、ずれた位置にあってもよい。 As shown in FIGS. 2A and 2B, the center of the conversion unit 106 a included in the pixel 201 a and the conversion unit 106 b included in the pixel 201 b disposed opposite to each other over the entire imaging panels 101 a and 101 b. The centers may be arranged at positions that overlap each other. Here, the centers of the conversion units 106a and 106b may be the positions of the geometric gravity centers of the shapes of the conversion units 106a and 106b in the orthogonal projection with respect to the incident surface 111. Further, when the conversion units 106a and 106b are rectangular, they may be diagonal intersections. Further, the center of the conversion unit 106a and the center of the conversion unit 106b may be at a position shifted by about 5% or less of the length of the pitch of the conversion units 106a and 106b.

また、変換部１０６ａ、１０６ｂの形状とは、例えば、変換部１０６ａ、１０６ｂがｐｎ、ｐｉｎ、ＭＩＳ型などの変換素子であった場合、入射面１１１に対する正射影における、それぞれの変換素子の形状であってもよい。また例えば、同じ大きさの変換素子を用いて、変換素子上に配された配線層や遮光層などを用いて、変換素子に対する光（放射線）の入射する開口率を変えることによって変換部１０６ａ、１０６ｂの面積を変化させてもよい。この場合、変換部１０６ａ、１０６ｂの形状とは、入射面１１１に対する正射影における、光（放射線）を変換素子に透過するための開口部の形状であってもよい。すなわち、画素の開口率は、入射面１１１に対する正射影において、画素の面積に対する放射線又は光を感知可能な領域の面積の占有比率である。 The shape of the conversion units 106a and 106b is, for example, the shape of each conversion element in the orthogonal projection with respect to the incident surface 111 when the conversion units 106a and 106b are pn, pin, MIS type conversion elements. There may be. In addition, for example, by using a conversion element having the same size, and using a wiring layer or a light shielding layer disposed on the conversion element, the conversion unit 106a, by changing the aperture ratio of light (radiation) incident on the conversion element, The area of 106b may be changed. In this case, the shape of the conversion units 106a and 106b may be the shape of an opening for transmitting light (radiation) to the conversion element in an orthogonal projection with respect to the incident surface 111. In other words, the aperture ratio of the pixel is an occupation ratio of the area of the region where radiation or light can be sensed with respect to the area of the pixel in the orthogonal projection with respect to the incident surface 111.

画素アレイ１０３ａ、１０３ｂに入射する放射線１１０は、画素アレイ１０３ａ、１０３ｂの中心側から外周側に進むに従って、より斜めに入射することが考えられる。そこで、図３に示すように、放射線源から遠い撮像パネル１０１ｂの画素アレイ１０３ｂに配された画素２０１ｂが有する変換部１０６ｂ’は、画素アレイ１０３ｂの外周側では変換部１０６ｂ’の中心が、画素２０１ｂの中心に対して外周側に偏っていてもよい。つまり、画素アレイ１０３ｂの中心から離れて配された画素２０１ｂが有する変換部１０６ｂ’の中心が、互いに相対する位置に配された画素２０１ａが有する変換部１０６ａの中心に対して画素アレイ１０３ａ、１０３ｂの外周側にずれて配される。この場合、図３（ｂ）に示すように、互いに相対する画素２０１ａ、２０１ｂに配された変換部１０６ａと変換部１０６ｂ’とは、入射面１１１に対する正射影において、互いに重なるように配されてもよい。つまり、変換部１０６ａと変換部１０６ｂ’との中心の位置は偏心するが、変換部１０６ｂ’の全体が、変換部１０６ａと重なる位置に配されてもよい。 It is conceivable that the radiation 110 incident on the pixel arrays 103a and 103b enters more obliquely as it proceeds from the center side to the outer peripheral side of the pixel arrays 103a and 103b. Therefore, as shown in FIG. 3, in the conversion unit 106b ′ included in the pixel 201b arranged in the pixel array 103b of the imaging panel 101b far from the radiation source, the center of the conversion unit 106b ′ is located on the outer peripheral side of the pixel array 103b. It may be biased toward the outer peripheral side with respect to the center of 201b. In other words, the center of the conversion unit 106b ′ included in the pixel 201b disposed away from the center of the pixel array 103b is aligned with the center of the conversion unit 106a included in the pixel 201a disposed in a position opposite to each other. It is shifted and arranged on the outer peripheral side. In this case, as shown in FIG. 3B, the conversion unit 106a and the conversion unit 106b ′ arranged in the pixels 201a and 201b facing each other are arranged so as to overlap each other in the orthogonal projection with respect to the incident surface 111. Also good. That is, the center positions of the conversion unit 106a and the conversion unit 106b 'are decentered, but the entire conversion unit 106b' may be disposed at a position overlapping the conversion unit 106a.

図３（ａ）は、画素アレイ１０３ａ、１０３ｂの外周側において、相対する画素２０１ａ、２０１ｂがそれぞれ有する変換部１０６ａと変換部１０６ｂ’とが、偏心して配された場合の断面図を示す。このとき、画素アレイ１０３ｂの中心に近接して配される画素２０１ｂが有する変換部１０６ｂの中心は、図３（ｂ）の平面図に示すように、互いに相対する位置に配された画素２０１ａが有する変換部１０６ａの中心と重なる位置に配されうる。つまり、画素アレイ１０３ａ、１０３ｂの中心に近接して配される画素２０１ａ、２０１ｂの断面は図２（ａ）と同様の構成を有しうる。 FIG. 3A is a cross-sectional view in the case where the conversion units 106a and 106b 'included in the opposing pixels 201a and 201b are arranged eccentrically on the outer peripheral side of the pixel arrays 103a and 103b. At this time, the center of the conversion unit 106b included in the pixel 201b arranged close to the center of the pixel array 103b is the pixel 201a arranged at a position facing each other, as shown in the plan view of FIG. It can be arranged at a position overlapping the center of the conversion unit 106a. That is, the cross sections of the pixels 201a and 201b arranged close to the centers of the pixel arrays 103a and 103b can have the same configuration as that in FIG.

図３（ｂ）に示す構成において、画素アレイ１０３ａ、１０３ｂの中心に近接し、互いの中心が重なる変換部１０６ａ、１０６ｂをそれぞれ有する画素２０１ａ、２０１ｂから、外周部に向かって徐々に変換部１０６ａ、１０６ｂ’の中心の位置が偏心してもよい。また例えば、中心から外周部に向かって、段階的に変換部１０６ａ、１０６ｂ’の中心の位置が偏心してもよい。また、画素アレイ１０３ｂの外周部における画素２０１ｂの変換部１０６ｂ’の偏りは、図３（ｂ）に示すように、行方向及び列方向の両方向に偏ってもよいし、行方向や列方向だけの偏りを有していてもよい。また、画素アレイ１０３ａに配されたそれぞれの画素２０１ａが有する変換部１０６ａの中心が、図２及び図３に示す構成において、一定のピッチで配されていてもよい。図２に示す構成では、画素アレイ１０３ｂに配されたそれぞれの画素２０１ｂが有する変換部１０６ｂの中心は、一定のピッチで配されうる。これに対して、図３に示す構成では、画素アレイ１０３ｂに配されたそれぞれの画素２０１ｂが有する変換部１０６ｂの中心は、一定のピッチで配されない部分を有する。 In the configuration shown in FIG. 3B, from the pixels 201a and 201b having the conversion units 106a and 106b that are close to the centers of the pixel arrays 103a and 103b and overlap each other, gradually convert toward the outer periphery. , 106b ′ may be eccentric. Further, for example, the positions of the centers of the conversion units 106 a and 106 b ′ may be decentered stepwise from the center toward the outer periphery. Further, as shown in FIG. 3B, the bias of the conversion unit 106b ′ of the pixel 201b in the outer periphery of the pixel array 103b may be biased in both the row direction and the column direction, or only in the row direction and the column direction. May have a bias of. In addition, the centers of the conversion units 106a included in the respective pixels 201a arranged in the pixel array 103a may be arranged at a constant pitch in the configuration shown in FIGS. In the configuration illustrated in FIG. 2, the centers of the conversion units 106b included in the respective pixels 201b arranged in the pixel array 103b can be arranged at a constant pitch. On the other hand, in the configuration shown in FIG. 3, the center of the conversion unit 106b included in each pixel 201b arranged in the pixel array 103b has a portion that is not arranged at a constant pitch.

また、図２、３に示すように画素アレイ１０３ａに配された画素２０１ａの有する変換部１０６ａの面積が、画素アレイ１０３ａ内ですべて同じであってもよい。また、画素アレイ１０３ｂに配された画素２０１ｂの有する変換部１０６ｂの面積が、画素アレイ１０３ｂ内ですべて同じであってもよい。このとき、撮像パネル１０１ｂの各画素２０１ｂが有する変換部１０６ｂの面積が、相対して配された撮像パネル１０１ａの画素２０１ａが有する変換部１０６ａの面積の５０％以上かつ９０％以下であってもよい。更に、撮像パネル１０１ｂの各画素２０１ｂが有する変換部１０６ｂの面積が、相対して配された撮像パネル１０１ａの画素２０１ａが有する変換部１０６ａの面積の６０％以上かつ７０％以下であってもよい。ここで、変換部１０６ａ、１０６ｂの面積とは、例えば、変換部１０６ａ、１０６ｂがｐｎ、ｐｉｎ、ＭＩＳ型などの変換素子であった場合、入射面１１１に対する正射影における、それぞれの変換素子の面積であってもよい。また例えば、変換素子上に配された配線層や遮光層などを用いて、変換素子に入射する光（放射線）の量を変化させる場合、変換部１０６ａ、１０６ｂの面積とは、入射面１１１に対する正射影における、光を変換素子に透過するための開口部の面積であってもよい。 Further, as shown in FIGS. 2 and 3, the areas of the conversion units 106a included in the pixels 201a arranged in the pixel array 103a may be the same in the pixel array 103a. Further, the area of the conversion unit 106b included in the pixel 201b arranged in the pixel array 103b may be the same in the pixel array 103b. At this time, even if the area of the conversion unit 106b included in each pixel 201b of the imaging panel 101b is 50% or more and 90% or less of the area of the conversion unit 106a included in the pixel 201a of the imaging panel 101a that is disposed in a relative manner. Good. Furthermore, the area of the conversion unit 106b included in each pixel 201b of the imaging panel 101b may be 60% or more and 70% or less of the area of the conversion unit 106a included in the pixel 201a of the imaging panel 101a disposed in a relative manner. . Here, the areas of the conversion units 106a and 106b are, for example, when the conversion units 106a and 106b are pn, pin, MIS type conversion elements, and the like, in the orthogonal projection with respect to the incident surface 111. It may be. Further, for example, when the amount of light (radiation) incident on the conversion element is changed using a wiring layer or a light shielding layer disposed on the conversion element, the areas of the conversion units 106 a and 106 b are relative to the incident surface 111. It may be the area of the opening for transmitting light to the conversion element in orthographic projection.

また、被写体を配さないで撮影した際、入射する放射線のうち低エネルギ側の放射線を検出する撮像パネル１０１ａの感度をＩａ、撮像パネル１０１ａを透過した高エネルギの放射線を検出する撮像パネル１０１ｂの感度をＩｂとする。画素アレイ１０３ａに配される各画素２０１ａの変換部１０６ａよりも画素アレイ１０３ｂに配される各画素２０１ｂの変換部１０６ｂの方が小さいため、同じ強度の放射線に対する信号の出力が、変換部１０６ａよりも変換部１０６ｂの方が小さくなりうる。変換部１０６ａ、１０６ｂの面積の違いによって発生する感度低下の影響を軽減するために、変換部１０６ａよりも変換部１０６ｂの方が、同じ強度の放射線に対して感度が高くてもよい。例えば、変換部１０６ａ、１０６ｂがＭＩＳ型の変換素子の場合、変換部１０６ａと変換部１０６ｂとで、変換素子の半導体領域や絶縁膜の厚さを変化させてもよい。また例えば、変換部１０６ａ、１０６ｂがｐｎ、ｐｉｎ型の変換素子の場合、変換部１０６ａと変換部１０６ｂとで、変換素子のそれぞれのｐ型、ｎ型、ｉ型の半導体領域の厚さを変化させてもよい。また例えば、シンチレータ１０４ａとシンチレータ１０４ｂとで膜厚や用いる材料を変化させてもよい。また例えば、それぞれの画素２０１ａ、２０１ｂから信号を読み出す読出回路のＩＣゲインを、画素アレイ１０３ａと画素アレイ１０３ｂとで変化させてもよい。 In addition, when photographing without a subject, the sensitivity of the imaging panel 101a that detects low-energy radiation among the incident radiation is Ia, and the imaging panel 101b that detects high-energy radiation transmitted through the imaging panel 101a. Let sensitivity be Ib. Since the conversion unit 106b of each pixel 201b arranged in the pixel array 103b is smaller than the conversion unit 106a of each pixel 201a arranged in the pixel array 103a, a signal output for radiation of the same intensity is output from the conversion unit 106a. Also, the conversion unit 106b can be smaller. In order to reduce the influence of the sensitivity reduction caused by the difference in the areas of the conversion units 106a and 106b, the conversion unit 106b may be more sensitive to radiation of the same intensity than the conversion unit 106a. For example, when the conversion units 106a and 106b are MIS type conversion elements, the thickness of the semiconductor region or the insulating film of the conversion elements may be changed between the conversion unit 106a and the conversion unit 106b. Further, for example, when the conversion units 106a and 106b are pn and pin type conversion elements, the conversion unit 106a and the conversion unit 106b change the thicknesses of the p-type, n-type, and i-type semiconductor regions of the conversion elements. You may let them. Further, for example, the film thickness and the material used may be changed between the scintillator 104a and the scintillator 104b. Further, for example, the IC gain of the readout circuit that reads signals from the respective pixels 201a and 201b may be changed between the pixel array 103a and the pixel array 103b.

また、画素アレイ１０３ｂにおいて、各画素２０１ｂが有する変換部１０６ｂの面積を画素アレイ１０３の中心から外周側に進むに従って、変化させてもよい。例えば、画素アレイ１０３ｂの中心に近接する画素２０１ｂに対して、放射線１１０は垂直に近い角度で入射し、相対する画素２０１ａを透過した放射線は入射し難くなりうる。このため、画素アレイ１０３ｂの中心に近接する画素２０１ｂが有する変換部１０６ｂは、例えば、画素アレイ１０３ａに配される変換部１０６ａの９０％の面積を有してもよい。一方で、画素アレイ１０３ｂの外周に近接する画素２０１ｂに対して、放射線１１０は斜めに入射しうる。当該画素２０１ｂの変換部１０６ｂ’は、画素アレイ１０３ａの相対する位置に配された画素２０１ａ以外を透過した放射線を検出しないために、変換部１０６ａに対して外周側に偏心し、変換部１０６ａの５０％の面積を有していてもよい。つまり、画素アレイ１０３ｂの中心に近接する画素２０１ｂが有する変換部１０６ｂが、画素アレイ１０３ｂの外周部に近接する画素２０１ｂが有する変換部１０６ｂ’よりも大きくてもよい。画素アレイ１０３ｂ内で変換部１０６ｂの面積の違いによって発生する感度の変化は、それぞれの画素２０１ｂから信号を読み出す読出回路のＩＣゲインを変化させることで補正してもよい。 In the pixel array 103b, the area of the conversion unit 106b included in each pixel 201b may be changed from the center of the pixel array 103 toward the outer peripheral side. For example, the radiation 110 may enter the pixel 201b close to the center of the pixel array 103b at an angle close to vertical, and the radiation transmitted through the opposing pixel 201a may be difficult to enter. Therefore, the conversion unit 106b included in the pixel 201b close to the center of the pixel array 103b may have, for example, 90% of the area of the conversion unit 106a arranged in the pixel array 103a. On the other hand, the radiation 110 can be incident obliquely on the pixels 201b close to the outer periphery of the pixel array 103b. The conversion unit 106b ′ of the pixel 201b is eccentric to the outer peripheral side with respect to the conversion unit 106a in order not to detect radiation that has passed through other than the pixel 201a arranged at the opposite position of the pixel array 103a. It may have an area of 50%. That is, the conversion unit 106b included in the pixel 201b adjacent to the center of the pixel array 103b may be larger than the conversion unit 106b 'included in the pixel 201b adjacent to the outer periphery of the pixel array 103b. The change in sensitivity caused by the difference in the area of the conversion unit 106b in the pixel array 103b may be corrected by changing the IC gain of the readout circuit that reads a signal from each pixel 201b.

また、本実施形態において、図１に示すように撮像パネル１０１ａと撮像パネル１０１ｂとは、結合層１０７を介して互いにシンチレータ１０４ａ、１０４ｂが入射面１１１の方向を向くように重ねられる。しかしながら、撮像パネル１０１ａと撮像パネル１０１ｂとを重ねる構成は、これに限られるものではない。 In the present embodiment, as shown in FIG. 1, the imaging panel 101 a and the imaging panel 101 b are overlapped with each other through the coupling layer 107 so that the scintillators 104 a and 104 b face the direction of the incident surface 111. However, the configuration in which the imaging panel 101a and the imaging panel 101b are overlapped is not limited to this.

例えば、図４（ａ）に示すように、撮像パネル１０１ａと撮像パネル１０１ｂとの間に、撮像パネル１０１ａを透過する放射線の一部を吸収する放射線吸収層４０１を配してもよい。撮像パネル１０１ａは低エネルギの放射線を検出し、撮像パネル１０１ｂは、撮像パネル１０１ａを透過した高いエネルギを有する放射線を検出しうる。しかしながら、撮像パネル１０１ａで、低エネルギ側のエネルギを全て吸収できるとは限らない。そこで、放射線吸収層４０１を、撮像パネル１０１ａと撮像パネル１０１ｂとの間に配することによって、撮像パネル１０１ａを透過した放射線のうち低エネルギの成分を吸収することによって、得られるエネルギサブトラクション画像の画質の向上が可能となる。放射線吸収層には、例えば金、銀、銅などの金属材料やその合金を用いてもよい。 For example, as shown in FIG. 4A, a radiation absorbing layer 401 that absorbs part of the radiation that passes through the imaging panel 101a may be disposed between the imaging panel 101a and the imaging panel 101b. The imaging panel 101a can detect low-energy radiation, and the imaging panel 101b can detect radiation having high energy that has passed through the imaging panel 101a. However, the imaging panel 101a cannot always absorb all of the energy on the low energy side. Therefore, by disposing the radiation absorbing layer 401 between the imaging panel 101a and the imaging panel 101b, the image quality of the energy subtraction image obtained by absorbing the low energy component of the radiation transmitted through the imaging panel 101a. Can be improved. For the radiation absorbing layer, for example, a metal material such as gold, silver, copper, or an alloy thereof may be used.

また例えば、図４（ｂ）に示すように、撮像パネル１０１ａと撮像パネル１０１ｂとの基板１０２ａ、１０２ｂが結合層１０７を介して互いに隣接していてもよい。また例えば、図４（ｃ）に示すように、撮像パネル１０１ａと撮像パネル１０１ｂとのシンチレータ１０４ａ、１０４ｂが結合層１０７を介して互いに隣接していてもよい。これらの場合も、撮像パネル１０１ａと撮像パネル１０１ｂとの間に、上述の放射線吸収層４０１が配されていてもよい。 Further, for example, as illustrated in FIG. 4B, the substrates 102 a and 102 b of the imaging panel 101 a and the imaging panel 101 b may be adjacent to each other via the coupling layer 107. Further, for example, as shown in FIG. 4C, scintillators 104 a and 104 b of the imaging panel 101 a and the imaging panel 101 b may be adjacent to each other via a coupling layer 107. Also in these cases, the above-described radiation absorbing layer 401 may be disposed between the imaging panel 101a and the imaging panel 101b.

＜実施例＞
次いで、本実施形態の実施例について説明する。 <Example>
Next, examples of the present embodiment will be described.

第１の実施例
上述の図２に示す構造を有する放射線撮像装置１００を作製した。まず、５５０ｍｍ×４４５ｍｍ×ｔ０．７ｍｍの無アルカリガラスの基板の上に、アモルファスシリコン（非晶質シリコン）を用いた半導体層を形成した。次いで、半導体層に光を電気信号に変換するための変換部１０６ａ、１０６ｂとＴＦＴとで構成される画素などを含む画素アレイ１０３ａ、１０３ｂを、真空成膜やフォトエッチングプロセスなどを繰り返すことによって形成した。画素アレイ１０３ａ、１０３ｂは、それぞれ画素数２８１６×３４１６、画素ピッチ１２５μｍの構成を有する。画素アレイ１０３ａ、１０３ｂに配された画素のうち、外周部に配された各８画素は、画素アレイ１０３ａ、１０３ｂ作成時のドライエッチングなどのプロセスマージンを確保するために形成される所謂ダミー画素である。これらダミー画素は、有効画素領域の外周部に約１．２ｍｍの幅で形成した。また、画素アレイ１０３ａ、１０３ｂとに含まれるエネルギサブトラクション画像を生成するための画素は、それぞれに互いに相対する画素を有し、画素アレイ１０３ａに含まれる画素の数と画素アレイ１０３ｂに含まれる画素の数とは同じである。 First Example A radiation imaging apparatus 100 having the structure shown in FIG. 2 was produced. First, a semiconductor layer using amorphous silicon (amorphous silicon) was formed on a non-alkali glass substrate having a size of 550 mm × 445 mm × t 0.7 mm. Next, pixel arrays 103a and 103b including pixels composed of conversion units 106a and 106b and TFTs for converting light into electrical signals are formed in the semiconductor layer by repeating vacuum film formation, a photoetching process, and the like. did. Each of the pixel arrays 103a and 103b has a configuration of 2816 × 3416 pixels and a pixel pitch of 125 μm. Of the pixels arranged in the pixel arrays 103a and 103b, eight pixels arranged in the outer peripheral portion are so-called dummy pixels formed to secure a process margin such as dry etching when the pixel arrays 103a and 103b are formed. is there. These dummy pixels were formed with a width of about 1.2 mm on the outer periphery of the effective pixel region. In addition, the pixels for generating the energy subtraction images included in the pixel arrays 103a and 103b have pixels opposed to each other, and the number of pixels included in the pixel array 103a and the number of pixels included in the pixel array 103b. The number is the same.

変換部１０６ａは、入射面１１１に対する正射影において、それぞれの画素２０１ａの面積に対して８０％の面積となるように画素２０１ａの開口率が構成されている。また、変換部１０６ｂは、入射面１１１に対する正射影において、それぞれの画素２０１ｂの面積に対して５０％の面積となるように画素２０１ｂの開口率が構成されている。換言すると、撮像パネル１０１ｂの画素アレイ１０３ｂの各画素２０１ｂが有する変換部１０６ｂの面積を、相対して配された撮像パネル１０１ａの画素アレイ１０３ａの各画素２０１ａが有する変換部１０６ａの面積の６２．５％とした。 In the conversion unit 106a, the aperture ratio of the pixel 201a is configured to have an area of 80% with respect to the area of each pixel 201a in the orthogonal projection with respect to the incident surface 111. Further, the aperture ratio of the pixel 201b is configured so that the conversion unit 106b has an area of 50% with respect to the area of each pixel 201b in the orthogonal projection with respect to the incident surface 111. In other words, the area of the conversion unit 106b included in each pixel 201b of the pixel array 103b of the image pickup panel 101b is equal to the area of the conversion unit 106a included in each pixel 201a of the pixel array 103a of the image pickup panel 101a disposed in a relative manner. 5%.

その後、画素アレイ１０３ａ、１０３ｂを保護する目的で、ＳｉＮ_ｘ層及びポリイミド樹脂層を形成し、画素アレイ１０３ａ、１０３ｂを得た。 Thereafter, for the purpose of protecting the pixel arrays 103a and 103b, an SiN _x layer and a polyimide resin layer were formed to obtain the pixel arrays 103a and 103b.

次いで、画素アレイ１０３ａ、１０３ｂ形成されたに配線部を保護するためのマスキング処理を実施した後、蒸着チャンバ中に画素アレイ１０３ａ、１０３ｂの形成された基板１０２ａ、１０２ｂを設置した。チャンバ内を１０^−５Ｐａまで減圧後、画素アレイ１０３ａ、１０３ｂの形成された基板１０２ａ、１０２ｂを回転させながら、画素アレイ１０３ａ、１０３ｂの表面が１８０℃となるようにランプ加熱を行い、ＣｓＩの蒸着を行った。この際、発光中心となるＴｌも同時に蒸着した。このようにして、画素アレイ１０３ａ、１０３ｂの上に、膜厚４００μｍ、Ｔｌ濃度１ｍｏｌ％のシンチレータ１０４ａ、１０４ｂを形成した。 Next, after performing masking processing for protecting the wiring portion on the pixel arrays 103a and 103b, the substrates 102a and 102b on which the pixel arrays 103a and 103b were formed were placed in the vapor deposition chamber. After reducing the pressure in the chamber to 10 ⁻⁵ Pa, while rotating the substrates 102a and 102b on which the pixel arrays 103a and 103b are formed, lamp heating is performed so that the surfaces of the pixel arrays 103a and 103b become 180 ° C. Vapor deposition was performed. At this time, Tl serving as the emission center was also deposited at the same time. In this manner, scintillators 104a and 104b having a film thickness of 400 μm and a Tl concentration of 1 mol% were formed on the pixel arrays 103a and 103b.

シンチレータ１０４ａ、１０４ｂの形成後、シンチレータ１０４ａ、１０４ｂの形成された画素アレイ１０３ａ、１０３ｂの形成された基板１０２ａ、１０２ｂを蒸着チャンバから取り出した。次いで、シンチレータ１０４ａ、１０４ｂの防湿保護と反射率確保のために、シンチレータ１０４ａ、１０４ｂを覆うように真空加熱ラミネーターにて保護層１０５ａ、１０５ｂを接着した。保護層１０５ａ、１０５ｂは、２０μｍ厚のＰＥＴと２０μｍ厚のＡｌとの積層シートを含み、接着目的で５０μｍ厚のホットメルト接着剤がコーティングされている。更に、周辺からの湿気混入を防ぐために、保護層１０５ａ、１０５ｂの周辺部を入念に加圧接着した。その後、気泡を抜くための加圧脱泡処理を行い、しかるべき電気実装と緩衝材の接着、および電気回路の接続、機構部分への実装などを行い、それぞれ画素が有する変換部１０６ａ、１０６ｂの面積が互いに異なる撮像パネル１０１ａ、１０１ｂを得た。 After the formation of the scintillators 104a and 104b, the substrates 102a and 102b on which the pixel arrays 103a and 103b on which the scintillators 104a and 104b were formed were taken out of the vapor deposition chamber. Next, in order to protect the scintillators 104a and 104b from moisture and to ensure reflectance, the protective layers 105a and 105b were bonded by a vacuum heating laminator so as to cover the scintillators 104a and 104b. The protective layers 105a and 105b include a laminated sheet of 20 μm thick PET and 20 μm thick Al, and are coated with a 50 μm thick hot melt adhesive for bonding purposes. Furthermore, in order to prevent moisture from entering from the periphery, the peripheral portions of the protective layers 105a and 105b were carefully pressure-bonded. Thereafter, pressure defoaming processing for removing bubbles is performed, and appropriate electrical mounting and buffering material bonding, electrical circuit connection, mounting on a mechanism portion, and the like are performed. Imaging panels 101a and 101b having different areas were obtained.

次いで、撮像パネル１０１ｂの保護層１０５ｂの形成された側に、結合層１０７として１０μｍ厚のアクリル粘着シートを転写し、離形フィルムを剥離した後、各画素の中心が撮像パネル１０１ａと撮像パネル１０１ｂとで重なるように基準で位置出しを行った。位置出しの後、結合層１０７を介して撮像パネル１０１ｂの保護層１０５ｂの形成された側を、撮像パネル１０１ａの基板１０２ａの側に貼り付けた。以上の工程を用いて、２つの撮像パネル１０１ａ、１０１ｂを積層し、１ショットでエネルギサブトラクションが可能な放射線撮像装置１００を得た。 Next, an acrylic adhesive sheet having a thickness of 10 μm is transferred as the bonding layer 107 to the side of the imaging panel 101b where the protective layer 105b is formed, and after the release film is peeled off, the center of each pixel is the imaging panel 101a and the imaging panel 101b. Positioning was performed based on the reference so that they overlap. After positioning, the side on which the protective layer 105b of the imaging panel 101b was formed was attached to the substrate 102a side of the imaging panel 101a through the bonding layer 107. Using the above steps, two imaging panels 101a and 101b were stacked to obtain a radiation imaging apparatus 100 capable of energy subtraction in one shot.

この放射線撮像装置１００に、管電圧１５０ｋＶ、管電流２００ｍＡ、固定ろ過１．９ｍｍ厚Ａｌ、付加フィルター無しの条件で、ＳＩＤ（ＳｏｕｒｃｅＩｍａｇｅｒｅｃｅｐｔｏｒＤｉｓｔａｎｃｅ）１３０ｃｍの位置から放射線を爆射した。放射線の曝射によって、撮像パネル１０１ａ、１０１ｂのそれぞれで放射線画像を取得した。 The radiation imaging apparatus 100 was exposed to radiation from a position of 130 cm SID (Source Image Receptor Distance) under the conditions of a tube voltage of 150 kV, a tube current of 200 mA, a fixed filtration of 1.9 mm thickness of Al, and no additional filter. Radiation images were acquired by the imaging panels 101a and 101b by radiation exposure.

撮像パネル１０１ａの保護層１０５ａの上にＭＴＦチャートを載せ、空間周波数２ｌｐ／ｍｍのＭＴＦの測定を行ったところ、撮像パネル１０１ａのＭＴＦは０．３５０、撮像パネル１０１ｂのＭＴＦは０．３２０であった。 An MTF chart was placed on the protective layer 105a of the imaging panel 101a, and MTF measurement at a spatial frequency of 2 lp / mm was performed. As a result, the MTF of the imaging panel 101a was 0.350 and the MTF of the imaging panel 101b was 0.320. It was.

第２の実施例
上述の図３に示す構造を有する放射線撮像装置１００を作製した。撮像パネル１０１ａは、上述の第１の実施例の撮像パネル１０１ａと同様の構成を有する。一方、本実施例の撮像パネル１０１ｂは、画素アレイ１０３ｂの中心から離れた位置に配された画素が有する変換部１０６ｂ’の中心は、相対する位置に配された画素が有する変換部１０６ａの中心に対して画素アレイ１０３ａ、１０３ｂの外周側にずれて配される。また、画素アレイ１０３ｂの中心に近接する画素において、相対する画素の変換部１０６ａの中心と重なる位置に変換部１０６ｂを有する。具体的には、画素アレイ１０３ａの相対する画素の変換部１０６ａの中心と重なる位置に変換部１０６ｂを有する画素を、画素アレイ１０３ｂに形成された２８１６×３４１６の画素のうち画素アレイ１０３ｂの中心側の１４０８×１７０８画素に配した。一方、それよりも画素アレイ１０３ｂの外周側に配された画素に、変換部１０６ｂ’の中心が画素アレイ１０３ａの相対する位置に配された画素の変換部１０６ａの中心に対して外周側へ偏心した位置に配された画素を配した。本実施例において、画素アレイ１０３ａにおいて画素２０１ａが配されるピッチの１５％分、変換部１０６ｂ’の中心を、画素アレイ１０３ａの相対する位置に配された画素の変換部１０６ａの中心に対して偏心させた。これら２つの撮像パネル１０１ａ、１０１ｂを上述の第１の実施例と同様の工程を用いて積層し、１ショットでエネルギサブトラクションが可能な放射線撮像装置１００を得た。 Second Example A radiation imaging apparatus 100 having the structure shown in FIG. 3 was produced. The imaging panel 101a has the same configuration as the imaging panel 101a of the first embodiment described above. On the other hand, in the imaging panel 101b of the present embodiment, the center of the conversion unit 106b ′ included in the pixel disposed at a position away from the center of the pixel array 103b is the center of the conversion unit 106a included in the pixel disposed at the opposite position. With respect to the outer peripheral side of the pixel arrays 103a and 103b. In addition, in the pixel close to the center of the pixel array 103b, the conversion unit 106b is provided at a position overlapping the center of the conversion unit 106a of the opposite pixel. Specifically, a pixel having the conversion unit 106b at a position overlapping the center of the conversion unit 106a of the opposite pixel of the pixel array 103a is a center side of the pixel array 103b among 2816 × 3416 pixels formed in the pixel array 103b. 1408 × 1708 pixels. On the other hand, the center of the conversion unit 106b ′ is decentered toward the outer periphery with respect to the center of the conversion unit 106a of the pixel arranged at the opposite position of the pixel array 103a in the pixel arranged on the outer circumference side of the pixel array 103b. Pixels arranged at the positions were arranged. In this embodiment, the center of the conversion unit 106b ′ is set to 15% of the pitch at which the pixels 201a are arranged in the pixel array 103a with respect to the center of the conversion unit 106a of the pixels arranged at the opposite positions of the pixel array 103a. Eccentric. These two imaging panels 101a and 101b were stacked using the same process as in the first embodiment, and the radiation imaging apparatus 100 capable of energy subtraction in one shot was obtained.

撮像パネル１０１ａの保護層１０５ａの上にＭＴＦチャートを載せ、空間周波数２ｌｐ／ｍｍのＭＴＦの測定を行ったところ、撮像パネル１０１ａのＭＴＦは０．３５０、撮像パネル１０１ｂのＭＴＦは０．３３０であった。放射線源から遠い側の撮像パネル１０１ｂの画素アレイ１０３ｂに配された画素の変換部１０６ｂのうち外周側に配された変換部１０６ｂ’を画素アレイ１０３ｂの外周側に偏心することによって、撮像パネル１０１ｂのＭＴＦを向上することが可能となった。これによって、エネルギサブトラクション画像のより高画質化が可能となる。 When an MTF chart was placed on the protective layer 105a of the imaging panel 101a and MTF measurement was performed at a spatial frequency of 2 lp / mm, the MTF of the imaging panel 101a was 0.350 and the MTF of the imaging panel 101b was 0.330. It was. The conversion unit 106b ′ disposed on the outer peripheral side of the pixel conversion unit 106b disposed on the pixel array 103b of the imaging panel 101b far from the radiation source is decentered toward the outer peripheral side of the pixel array 103b. It was possible to improve the MTF. As a result, the image quality of the energy subtraction image can be improved.

比較例
本実施形態に対する比較構造による比較例として、同じ面積の変換部１０６ａ、１０６ｂを有する画素２０１ａ、２０１ｂが配された画素アレイ１０３ａ、１０３ｂを備えた撮像パネル１０１ａ、１０１ｂを積層した放射線撮像装置を作製した。作製した放射線撮像装置は、変換部１０６ａ、１０６ｂの面積が互いに同じであること以外、上述の第１の実施例及び第２の実施例で作製した放射線撮像装置１００と同様の構成を有する。 Comparative Example As a comparative example using the comparative structure for the present embodiment, a radiation imaging apparatus in which imaging panels 101a and 101b including pixel arrays 103a and 103b in which pixels 201a and 201b having conversion units 106a and 106b having the same area are arranged are stacked. Was made. The produced radiation imaging apparatus has the same configuration as the radiation imaging apparatus 100 produced in the first and second embodiments described above, except that the areas of the conversion units 106a and 106b are the same.

撮像パネル１０１ａの保護層１０５ａの上にＭＴＦチャートを載せ、空間周波数２ｌｐ／ｍｍのＭＴＦの測定を行ったところ、撮像パネル１０１ａのＭＴＦは０．３５０、撮像パネル１０１ｂのＭＴＦは０．３００であった。放射線源から遠い側の撮像パネル１０１ｂに配された画素２０１ｂの変換部１０６ｂが大きく、相対する撮像パネル１０１ｂ画素２０１ａだけでなく近接する位置に配された画素２０１ａを透過した放射線を検出したため、ＭＴＦが低下したと考えられる。 An MTF chart was placed on the protective layer 105a of the imaging panel 101a, and MTF measurement at a spatial frequency of 2 lp / mm was performed. The MTF of the imaging panel 101a was 0.350 and the MTF of the imaging panel 101b was 0.300. It was. Since the conversion unit 106b of the pixel 201b arranged on the imaging panel 101b far from the radiation source is large and detects the radiation transmitted through the pixel 201a arranged not only at the opposing imaging panel 101b pixel 201a but also at a close position, the MTF is detected. Is thought to have declined.

１回の放射線の照射でエネルギサブトラクション画像を取得するための放射線撮像装置１００において、撮像パネル１０１ａと撮像パネル１０１ｂとで、各画素２０１ａ、２０１ｂに配される変換部１０６ａ、１０６ｂの面積を変える。具体的には、放射線源から遠い撮像パネル１０１ｂの画素２０１ｂに配される変換部１０６ｂを、放射線の入射する側の撮像パネル１０１ａの画素２０１ａに配される変換部１０６ａよりも小さくする。これによって、撮像パネル１０１ａと撮像パネル１０１ｂとで、互いに重なる位置の画素以外を透過した放射線を検出することに起因するノイズ軽減し、得られるエネルギサブトラクション画像の空間分解能を向上することが可能となった。また、放射線源から遠い撮像パネル１０１ｂの画素アレイ１０３ｂの画素２０１ｂが有する変換部１０６ｂを画素アレイ１０３ｂの外周側で、変換部１０６ｂの中心を偏心する。これによって、さらに得られるエネルギサブトラクション画像の空間分解能を向上できることが分かった。 In the radiation imaging apparatus 100 for acquiring an energy subtraction image by one-time irradiation, the areas of the conversion units 106a and 106b arranged in the pixels 201a and 201b are changed between the imaging panel 101a and the imaging panel 101b. Specifically, the conversion unit 106b arranged in the pixel 201b of the imaging panel 101b far from the radiation source is made smaller than the conversion unit 106a arranged in the pixel 201a of the imaging panel 101a on the radiation incident side. As a result, the image pickup panel 101a and the image pickup panel 101b can reduce noise caused by detecting radiation that has passed through pixels other than the overlapping pixels, and improve the spatial resolution of the obtained energy subtraction image. It was. Further, the conversion unit 106b included in the pixel 201b of the pixel array 103b of the imaging panel 101b far from the radiation source is decentered on the outer peripheral side of the pixel array 103b. As a result, it was found that the spatial resolution of the obtained energy subtraction image can be improved.

以上、本発明に係る実施形態、実施例を示したが、本発明はこれらの実施形態、実施例に限定されないことはいうまでもなく、本発明の要旨を逸脱しない範囲で、上述した実施形態、実施例は適宜変更、組み合わせが可能である。 As mentioned above, although embodiment and the Example which concern on this invention were shown, it cannot be overemphasized that this invention is not limited to these embodiment and Example, Embodiment mentioned above in the range which does not deviate from the summary of this invention. The embodiments can be appropriately changed and combined.

＜放射線撮像システム＞
以下、図６を参照しながら本発明の放射線撮像装置１００が組み込まれた放射線撮像システム６００を例示的に説明する。放射線撮像システム６００は、例えば、放射線撮像装置１００と、イメージプロセッサなどを含む信号処理部６０３と、ディプレイなどを含む表示部６０４と、放射線を発生させるための放射線源６０１とを含む。放射線源６０１から発せられた放射線（例えばＸ線）は、被験者６０２を透過し、被験者６０２の体内の情報を含む放射線が、本実施形態の放射線撮像装置１００によって検出される。これによって得られた放射線画像を用いて、例えば、信号処理部６０３は、所定の信号処理を行い、画像データを生成する。この画像データは、表示部６０４に表示される。 <Radiation imaging system>
Hereinafter, a radiation imaging system 600 in which the radiation imaging apparatus 100 of the present invention is incorporated will be described with reference to FIG. The radiation imaging system 600 includes, for example, a radiation imaging apparatus 100, a signal processing unit 603 including an image processor, a display unit 604 including a display, and a radiation source 601 for generating radiation. Radiation (for example, X-rays) emitted from the radiation source 601 passes through the subject 602, and radiation including information in the body of the subject 602 is detected by the radiation imaging apparatus 100 of the present embodiment. For example, the signal processing unit 603 performs predetermined signal processing using the radiographic image obtained thereby, and generates image data. This image data is displayed on the display unit 604.

１００：放射線撮像装置、１０１ａ、１０１ｂ：撮像パネル、１０３ａ、１０３ｂ：画素アレイ、１０６ａ、１０６ｂ：変換部、１１１：入射面、２０１ａ、２０１ｂ：画素 DESCRIPTION OF SYMBOLS 100: Radiation imaging device, 101a, 101b: Imaging panel, 103a, 103b: Pixel array, 106a, 106b: Conversion part, 111: Incidence surface, 201a, 201b: Pixel

Claims

A first imaging panel comprising a first pixel array including a first pixel for outputting a signal corresponding to radiation or light arranged in a matrix;
A second imaging panel including a second pixel array including a second pixel for outputting a signal corresponding to radiation or light arranged in a matrix.
The first imaging panel and the second imaging panel are stacked in this order from the incident surface side for irradiating radiation so that the first pixel array and the second pixel array overlap each other. A radiation imaging device,
A radiation imaging apparatus, wherein the aperture ratio of the second pixel is smaller than the aperture ratio of the first pixel.

Each pixel included in the first pixel array and the second pixel array has a conversion unit for outputting a signal corresponding to incident radiation,
2. The radiation imaging according to claim 1, wherein an area of the conversion unit included in the second pixel is smaller than an area of the conversion unit included in the first pixel in an orthogonal projection with respect to the incident surface. apparatus.

In the orthogonal projection with respect to the incident surface, the conversion unit included in the first pixel such that the center of the conversion unit included in the first pixel and the center of the conversion unit included in the second pixel overlap each other. The radiation imaging apparatus according to claim 2, wherein the second imaging unit and the conversion unit included in the second pixel are arranged to overlap each other.

The first pixel array further includes a third pixel disposed on an outer peripheral side of the first pixel array with respect to a center of the first pixel array with respect to the first pixel,
The second pixel array further includes a fourth pixel disposed on an outer peripheral side of the second pixel array with respect to a center of the second pixel array with respect to the second pixel,
In the orthogonal projection with respect to the incident surface, the area of the conversion unit is smaller in the fourth pixel than the third pixel, and the center of the conversion unit included in the fourth pixel is the third pixel. 4. The radiation imaging according to claim 2, wherein the center of the first pixel array is shifted to an outer peripheral side of the first pixel array with respect to a center of the first pixel array with respect to a center of the conversion unit included in the pixel. apparatus.

5. The orthographic projection with respect to the incident surface, wherein the conversion unit included in the third pixel and the conversion unit included in the fourth pixel are arranged so as to overlap each other. Radiation imaging device.

In the orthogonal projection with respect to the incident surface, the area of the conversion unit included in the first pixel and the area of the conversion unit included in the third pixel are the same.
The area of the conversion unit included in the second pixel and the area of the conversion unit included in the fourth pixel are the same in orthogonal projection with respect to the incident surface. Radiation imaging device.

In the orthogonal projection with respect to the incident surface, the area of the conversion unit included in the first pixel and the area of the conversion unit included in the third pixel are the same.
The orthographic projection with respect to the said entrance plane WHEREIN: The area of the said conversion part which the said 2nd pixel has is larger than the area of the said conversion part which the said 4th pixel has, The Claim 4 or 5 characterized by the above-mentioned. Radiation imaging device.

The radiation imaging apparatus according to claim 2, wherein centers of the conversion units included in the respective pixels included in the first pixel array are arranged at a constant pitch. .

The conversion unit included in each pixel included in the second pixel is more sensitive to radiation of the same intensity than the conversion unit included in each pixel included in the first pixel array. The radiation imaging apparatus according to claim 2, wherein the radiation imaging apparatus is characterized.

The area of the conversion unit included in the second pixel is 50% or more and 90% or less of the area of the conversion unit included in the first pixel in the orthogonal projection with respect to the incident surface. Item 10. The radiation imaging apparatus according to any one of Items 2 to 9.

Each of the first imaging panel and the second imaging panel includes a scintillator,
The radiation imaging apparatus according to claim 2, wherein the conversion unit detects light converted from radiation by the scintillator.

The number of pixels included in the pixel array arranged in the first imaging panel is the same as the number of pixels contained in the pixel array arranged in the second imaging panel. The radiation imaging apparatus of any one of thru | or 11.

The radiation absorption layer for absorbing a part of radiation which permeate | transmitted the said 1st imaging panel is included between the said 1st imaging panel and the said 2nd imaging panel. The radiation imaging apparatus according to any one of 12.

The radiation imaging apparatus according to any one of claims 1 to 13,
A radiation imaging system comprising: a signal processing unit that processes a signal from the radiation imaging apparatus.