WO2007145109A1 - Appareil de tomodensitométrie ayant une direction de rayonnement des rayons x et une orientation du détecteur fixées dans des directions arbitraires, et procédé de reconstitution d'une image en trois dimensions et programme pour l'appareil - Google Patents

Appareil de tomodensitométrie ayant une direction de rayonnement des rayons x et une orientation du détecteur fixées dans des directions arbitraires, et procédé de reconstitution d'une image en trois dimensions et programme pour l'appareil Download PDF

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Publication number
WO2007145109A1
WO2007145109A1 PCT/JP2007/061429 JP2007061429W WO2007145109A1 WO 2007145109 A1 WO2007145109 A1 WO 2007145109A1 JP 2007061429 W JP2007061429 W JP 2007061429W WO 2007145109 A1 WO2007145109 A1 WO 2007145109A1
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WO
WIPO (PCT)
Prior art keywords
projection
data
image reconstruction
image data
image
Prior art date
Application number
PCT/JP2007/061429
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English (en)
Japanese (ja)
Inventor
Haiquan Yang
Meihua Li
Kazuhito Koizumi
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Uni-Hite System Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Uni-Hite System Corporation filed Critical Uni-Hite System Corporation
Publication of WO2007145109A1 publication Critical patent/WO2007145109A1/fr

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/003—Reconstruction from projections, e.g. tomography
    • G06T11/006—Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2211/00—Image generation
    • G06T2211/40—Computed tomography
    • G06T2211/421—Filtered back projection [FBP]

Definitions

  • CT device with X-ray irradiation direction and detector orientation set in any direction, its 3D image reconstruction method and program
  • the present invention relates to a radiation (especially X-ray) CT apparatus and a three-dimensional image reconstruction method thereof, and in particular, a CT apparatus in which an X-ray irradiation direction and a detector orientation are set in arbitrary directions and a three-dimensional image reconstruction method thereof. And a program for the same.
  • Non-patent Document 1 Regarding a three-dimensional image reconstruction method using an X-ray CT apparatus, for example, there is a skew CT apparatus described in Patent Document 1.
  • the FDK method is generally known as a conventional three-dimensional reconstruction method of projection data (Non-patent Document 1).
  • Patent Document 1 Japanese Patent Laid-Open No. 2003-344316
  • Non-patent literature 1 L. A. Feldkamp, L. C. Davis, and J. W. Kress, Practical cone-beam algorism ", J. Opt. Soc. Am., A. Vol. 1, No. 6, pp.612-619, 1984
  • the detection surface is fixed so as to be orthogonal to the straight line connecting the X-ray focal point and the rotation center point of the measurement object, and then the measurement object is placed on the turntable.
  • the object to be measured is obtained by detecting a plurality of 2D projection data images by rotating the turntable once and reconstructing an image from the detected 2D projection data images. 3D image of the internal structure.
  • the image reconstruction method often used is the FDK method.
  • the FDK method was proposed by Feldkamp, Davis, and Kress, and is the mainstream reconstruction method (Non-patent Document 1).
  • the FDK method is a reconstruction method that can be applied when the X-ray source and detection surface are arranged as shown in Fig. 1.
  • the magnification with respect to the target object depends on the position of the X-ray source, the turntable, and the detector. There is a drawback that it is decided.
  • This device irradiates the target object with X-rays obliquely, and the detector is arranged so as to be orthogonal to the X-ray oblique irradiation direction, and the obtained image is applied to the FDK method. Therefore, projective transformation is performed on the captured image. It turned out that this conversion has the problem that the resolution of the target object is lowered. Moreover, since there is no degree of freedom in the inclination of the detector, there is a drawback that the magnification is also determined by the position of the X-ray source, the rotary table, and the detector.
  • the present invention has been made in view of eliminating these drawbacks. That is, the present invention relates to a three-dimensional image reconstruction method and apparatus, and a product of a prod- The issue is to provide a program.
  • the coordinate system of the reconstruction space is (x, y, z)
  • the coordinate system of the two-dimensional detector plane is (p, q)
  • the projection angle ⁇ is at the point (p, q) on the detector plane. If the projection value is P (p, q), the point (x, y, z)
  • D is the distance to the center of the X-ray focal force measurement object
  • t cos ⁇ + v in ⁇
  • the (p, q) coordinate system is a coordinate system fixed to the detection surface, but the FDK method considers reconstruction by moving the (p, q) coordinate system to the coordinate system in the reconstruction space.
  • the three-dimensional image reconstruction method performed by equation (1) is performed by the following procedure.
  • Weight projection data This “weight” is a weight related to the distance D taking into account the detected object coordinate systems p and q.
  • one degree of freedom ⁇ in the X-ray irradiation direction and two degrees of freedom in the inclination (orientation) of the detector are two degrees of freedom in the inclination (orientation) of the detector.
  • the CT image construction method for forming a three-dimensional image of a measurement object is: (1) X-rays transmitted through a measurement object arranged at a predetermined distance from an X-ray source; A process of preparing an X-ray CT device with a detection surface to be detected;
  • a CT image reconstruction method including a step of performing image reconstruction from a detected projection data image and displaying an internal structure of a measurement object
  • a CT image reconstruction device for converting a measurement object into a three-dimensional image.
  • This apparatus is an X-ray CT apparatus provided with a detection surface for detecting X-rays transmitted through a measurement object arranged at a predetermined distance from an X-ray source. Orient the detection surface of the detector in any direction with respect to the straight line connecting the X-ray source and the center of the object to be measured,
  • a C ⁇ image reconstruction device that performs image reconstruction from the detected projection data image and displays the internal structure of the measurement object
  • (A) means for applying a predetermined weight to the projection image data
  • (B) means for filtering the weighted projection image data
  • (C) means for performing back projection on the filtered data in a predetermined manner in a three-dimensional reconstruction space.
  • a program for carrying out the method of the basic configuration 1 is provided.
  • the apparatus and the three-dimensional image reconstruction method of the present invention that gives the degree of freedom to the X-ray irradiation direction and the detector tilt according to the present invention described in detail above can realize high magnification and miniaturization of the apparatus.
  • image reconstruction can be performed without conversion on a projection data image detected by an oblique CT apparatus, a laminography apparatus, or the like.
  • the present invention provides a three-dimensional image reconstruction method that can be achieved with high resolution and downsizing with an oblique CT apparatus (Japanese Patent Application Laid-Open No. 2003-344316). Since it can be used for image reconstruction, there is an advantage that the quality of the reconstructed image is improved.
  • the reconstruction algorithm is performed in the following steps.
  • a unique weight is applied to the projection data.
  • the present invention provides one degree of freedom in the X-ray irradiation direction and two degrees of freedom in the inclination of the detector.
  • the resolution of the target object can be improved.
  • FIG. 1 is an explanatory diagram of a conventional coordinate system for reconstructing a three-dimensional X-ray CT image.
  • FIG. 2 is an explanatory diagram for a coordinate system in which an X-ray irradiation direction according to the present invention is set to an arbitrary direction and detectors are also arranged in an arbitrary direction.
  • the detection surface is a surface constituted by a dotted line.
  • FIG. 4 (a) Phantom, (b) A longitudinal section of the center of a 3D image reconstructed by the method of the present invention for the projection data image detected by the apparatus of [Fig. 3], (c) [Fig. A longitudinal section of the center of a three-dimensional image reconstructed using the FDK method for the projection data image detected by the device in [1].
  • FIG. 6 Cross-sectional images of the center of the reconstructed three-dimensional image under the same angle conditions as in Fig. 5, and a profile along the dotted line at a position close to the end of these cross-sectional images.
  • FIG. 7 is a flowchart showing an embodiment of the three-dimensional CT image reconstruction procedure of the present invention.
  • CT image according to one of configurations 1 to 6, wherein R ⁇ jip sin (p-q sin ⁇ os ⁇ + R) '+ (p cos ⁇ + sin i? Sin q-cos ⁇ dy' is used Reconstruction method (Configuration 7) CT image reconstruction method according to any one of Configurations 1 to 7, wherein the orientation angle of the detection surface is used as the filter (Configuration 8)
  • the X-ray irradiation direction is irradiated at an angle ⁇ greater than 0 degrees with respect to the rotation axis of the measured object. ( ⁇ can be set by selecting the desired angle)
  • the detector is arranged according to the following procedure.
  • the three-dimensional image reconstruction in the present invention performed by equation (3) is performed by the following procedure.
  • This program is recorded on a recording medium provided in the control unit (especially its CPU), or can be transmitted via a communication line (wired or wireless), and can be remotely controlled from outside the shielding room as required. Can also be done.
  • FIG. 4 (a) a phantom, (b) a longitudinal section of the center of a three-dimensional image reconstructed according to the present invention from the projection data image detected by the apparatus of FIG. 3, and (c) FIG.
  • the longitudinal section of the center of the three-dimensional image reconstructed by the FDK method is shown for the projection data image detected by this device. From the experimental results in Fig. 4, the resolution of the central longitudinal section of the three-dimensional image reconstructed using the present invention compared to the device proposed in the present invention was reconstructed using the FDK method with the conventional device. It can be seen that it is sufficiently high compared to the captured image.
  • Fig. 5 shows each cross-sectional image and the profile along the center line of each cross-sectional image
  • Fig. 6 shows the profile along the dotted line at the position near the end of each cross-sectional image and each cross-sectional image. Show isle.
  • the profile of the present invention matches with high accuracy and has no inferiority compared to the phantom profile. It disappears and is integrated and displayed!
  • image reconstruction is performed with an essentially improved accuracy compared to the FDK method.
  • the X-ray irradiation method of the present invention and the three-dimensional image reconstruction method using a device in which the tilt orientation of the detector is arranged in an arbitrary direction are detected by a micro CT device, an oblique CT device, a laminography device, or the like.
  • the theoretically detected projection data image that can be directly applied to the projection data image has exactly the same effect as the projection data image detected by the above-mentioned apparatus, and is exactly the same as the geometric system in the reconstruction space. If so, there is a general feature that it can be applied easily.
  • This principle is not limited to the X-ray apparatus, and is generally applicable to three-dimensional image reconstruction in a radiation (including electron beam 'electromagnetic wave) CT apparatus.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Algebra (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Mathematical Physics (AREA)
  • Pure & Applied Mathematics (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

La présente invention concerne un appareil de tomodensitométrie à rayons X, dans lequel une direction de rayonnement des rayons X (c'est-à-dire, une direction d'une demi-droite rectiligne partant d'un foyer de rayons X et joignant le foyer des rayons X et le point central de rotation d'un objet) est fixée dans une direction arbitraire et dans lequel un détecteur est également disposé dans une direction arbitraire, et un procédé de reconstitution d'une image en trois dimensions pour l'appareil. La procédé de reconstitution d'image de tomodensitométrie permettant de transformer l'objet en une image à trois dimensions comprend: (1) l'étape consistant à préparer l'appareil de tomodensitométrie à rayons X en disposant une plaque de détection pour détecter un rayon X ayant traversé un objet disposé à une distance prédéterminée d'une source de rayons X, (2) l'étape consistant à orienter l'agencement de la plaque de détection du détecteur dans une direction arbitraire par rapport à la ligne droite joignant la source de rayons X et l'objet, (3) l'étape consistant à détecter l'irradiation de l'objet avec le rayon X à un angle plus grand que 0 degré dans la direction de rotation pour détecter de cette manière les données d'image de projection avec le détecteur, et (4) l'étape consistant à effectuer une reconstitution d'image à partir des données d'image de projection détectées, pour afficher la structure interne de l'objet en trois dimensions. Le procédé de reconstitution d'image par tomodensitométrie se caractérise en ce qu'il effectue les opérations consistant à (A) appliquer un poids prédéterminé aux données d'image de projection, (B) filtrer les données d'image de projection pondérées, et (C) projeter les données filtrées de manière inversée par un procédé prédéterminé dans un espace de reconstitution à trois dimensions.
PCT/JP2007/061429 2006-06-13 2007-06-06 Appareil de tomodensitométrie ayant une direction de rayonnement des rayons x et une orientation du détecteur fixées dans des directions arbitraires, et procédé de reconstitution d'une image en trois dimensions et programme pour l'appareil WO2007145109A1 (fr)

Applications Claiming Priority (2)

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JP2006-163695 2006-06-13
JP2006163695 2006-06-13

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WO2007145109A1 true WO2007145109A1 (fr) 2007-12-21

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103278515A (zh) * 2013-05-16 2013-09-04 华南理工大学 旋转式x射线分层摄影检测系统与方法
CN111077173A (zh) * 2020-01-03 2020-04-28 重庆大学 一种倒置结构大视场Mirco-CT扫描成像系统
CN111707687A (zh) * 2020-03-26 2020-09-25 国网河南省电力公司电力科学研究院 一种直线轨迹扫描ct检测方法及装置
CN114199905A (zh) * 2021-12-13 2022-03-18 中国航发南方工业有限公司 一种机匣内部缺陷的空间定位方法及系统

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JP2003344316A (ja) * 2002-05-27 2003-12-03 National Institute Of Advanced Industrial & Technology 傾斜三次元ｘ線ｃｔ画像の再構成方法
JP2004132931A (ja) * 2002-10-15 2004-04-30 Shimadzu Corp Ｘ線ｃｔ装置
JP2004138461A (ja) * 2002-10-17 2004-05-13 Tohken Co Ltd Ｘ線顕微検査装置
JP2005127886A (ja) * 2003-10-24 2005-05-19 Shimadzu Corp 傾斜型ｘ線ｃｔ装置における回転中心軸の較正方法および傾斜型ｘ線ｃｔ装置

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JP2003344316A (ja) * 2002-05-27 2003-12-03 National Institute Of Advanced Industrial & Technology 傾斜三次元ｘ線ｃｔ画像の再構成方法
JP2004132931A (ja) * 2002-10-15 2004-04-30 Shimadzu Corp Ｘ線ｃｔ装置
JP2004138461A (ja) * 2002-10-17 2004-05-13 Tohken Co Ltd Ｘ線顕微検査装置
JP2005127886A (ja) * 2003-10-24 2005-05-19 Shimadzu Corp 傾斜型ｘ線ｃｔ装置における回転中心軸の較正方法および傾斜型ｘ線ｃｔ装置

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103278515A (zh) * 2013-05-16 2013-09-04 华南理工大学 旋转式x射线分层摄影检测系统与方法
CN111077173A (zh) * 2020-01-03 2020-04-28 重庆大学 一种倒置结构大视场Mirco-CT扫描成像系统
CN111707687A (zh) * 2020-03-26 2020-09-25 国网河南省电力公司电力科学研究院 一种直线轨迹扫描ct检测方法及装置
CN114199905A (zh) * 2021-12-13 2022-03-18 中国航发南方工业有限公司 一种机匣内部缺陷的空间定位方法及系统
CN114199905B (zh) * 2021-12-13 2024-02-20 中国航发南方工业有限公司 一种机匣内部缺陷的空间定位方法及系统

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