WO2014122840A1 - Dispositif de génération d'images tdm et procédé de génération d'images tdm - Google Patents

Dispositif de génération d'images tdm et procédé de génération d'images tdm Download PDF

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Publication number
WO2014122840A1
WO2014122840A1 PCT/JP2013/082226 JP2013082226W WO2014122840A1 WO 2014122840 A1 WO2014122840 A1 WO 2014122840A1 JP 2013082226 W JP2013082226 W JP 2013082226W WO 2014122840 A1 WO2014122840 A1 WO 2014122840A1
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detector
projection
image generation
data
backprojection
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PCT/JP2013/082226
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English (en)
Japanese (ja)
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▲興▼▲東▼ 盛
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株式会社日立メディコ
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Priority to JP2014560646A priority Critical patent/JP6014174B2/ja
Publication of WO2014122840A1 publication Critical patent/WO2014122840A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
    • A61B6/5258—Devices using data or image processing specially adapted for radiation diagnosis involving detection or reduction of artifacts or noise
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/032—Transmission computed tomography [CT]

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  • the present invention relates to a CT image generation apparatus and a CT image generation method, and more particularly to a CT image generation apparatus and a CT image generation method using an improved separable footprint method.
  • CT X-ray computed tomography
  • the CT image reconstruction algorithm mainly includes a filter back projection method and an iterative reconstruction algorithm.
  • the filter back projection method is a conventional method of CT image reconstruction, and is widely applied in conventional CT products.
  • noise always exists with the projection data, especially in the case of low-dose scanning. Since it is remarkable, it becomes difficult to obtain a high-quality CT image.
  • the scope and depth of CT clinical application has gradually reached a high level that has not existed in the past. Under these new circumstances, the industry considers the safety of CT use. In addition, new high demands for image quality have emerged. This makes the filter backprojection method difficult to meet new demands.
  • the iterative reconstruction algorithm mainly includes a projection and backprojection process that are repeated many times, but the main procedure in the conventional filter backprojection algorithm is backprojection.
  • Projection and backprojection methods mainly include conventional ray-driven (Pay-Driven) and pixel-driven (Pixel-Driven) methods, but because of large model errors, it is not suitable for applications in iterative reconstruction algorithms. , It becomes difficult to converge the iterative algorithm. Therefore, highly accurate projection and backprojection methods have been researched and proposed, and the most typical ones are the recently proposed distance-driven (Separable Footprint) methods (for example, patent literature) 1, Patent Document 2). Of these, the separable footprint method is currently the best projection and backprojection model in the academic world, but this method is also a kind of approximation method, and there is still a certain model error, which further improves model accuracy. ⁇ Improvement is expected.
  • the main processor controls a projection / backprojection angle loop using the geometric parameter
  • the weight vector multiplication unit includes the X-ray scanner To multiply the scanned detector data by the weighting vector Ri, calculates a corrected detector value, the separable flask footprint calculation unit, by using the corrected detector value, and executes a separable footprint projection-back projection algorithm.
  • the CT image generation method includes an X-ray scanner that includes an X-ray source and a detector and detects an object disposed between the X-ray source and the detector, a detector data block, and weighting data.
  • a storage module including a block, a parameter data block, and an input / output result image data block;
  • a processor module including a main processor, a weight calculation unit, a weight vector multiplication unit, and a separable footprint calculation unit; and a data interface module
  • a CT image generation method of a CT image generation apparatus comprising: a user interface module, wherein data scanned by the X-ray scanner is stored as detector data in the detector data block via the data interface module Step to make
  • the weight calculation unit obtains a geometric parameter from the parameter data block and calculates a weight vector based on the geometric parameter; and the main processor uses the geometric parameter to project / A step of controlling a backprojection angle loop; a step in which the weight vector multiplication unit multiplies the detector data by the weight vector to obtain
  • the geometric parameters are the distance between the X-ray source and the detector, the detector element size, and the center position of the detector.
  • FIG. 2 is a diagram showing the principle of length-based projection / backprojection weighting.
  • the length when the projection line 201 passes through one of the pixels 202 is the correlation coefficient between the projection line 201 and the pixel, that is, the corresponding detector unit on which the projection line is projected.
  • the weighting coefficient is the projection and backprojection weighting 203 for the pixel unit.
  • This basic model is the basis of the separable footprint projection / backprojection method and the present invention.
  • FIG. 3 is a diagram showing the principle of separable footprint projection / backprojection method and its model error.
  • the separable footprint projection / backprojection method projection and backprojection on a predetermined pixel 301 start from the X-ray source 302, pass through four vertices of the pixel 301, respectively, and correspond to four corresponding on the detector 303.
  • the pixel values are each weighted and integrated into detector units within the four position ranges 304.
  • FIG. 3 is a diagram showing the principle of separable footprint projection / backprojection method and its model error.
  • Expression (2) P 1 , P 2 ..., P k are pixel values of all the pixels 502 on the path of the X-ray 501 in the drawing, and W 1 , W 2 ..., W k are separable footprint methods. 1 / sin ⁇ is a correction coefficient, that is, weighting. Expression (2) is converted into the following expression (3).
  • the integration after performing weighted correction on each pixel may be regarded as correcting after the weighted integration, that is, correcting the detector unit value obtained by projection, Even when the detector unit 503 value is reweighted by weighting (correction coefficient), the weighting coefficient corresponds to the position ⁇ of the detector unit 503 and the angle ⁇ determined by the perpendicular line 504 from the X-ray source to the detector. is doing.
  • the angle can be calculated by the following equation (4).
  • L 504 is the distance of a perpendicular line from the X-ray source of the detector to the detector
  • L 503 is the size of the detector unit
  • m is detected as a vertical line 504 from a predetermined detector unit. The number of detectors up to the intersection with the detector. Thus, a weighting vector as indicated by 505 in FIG. 5 is obtained.
  • FIG. 6 is a diagram showing detector data weighting by weighting vectors. After obtaining the weight vector 601, the projection and back projection processes were corrected by correspondingly multiplying the detector vector 602 composed of the detector values of the detector units in each column on the detector and the weight vector 601. A detector vector 603 is obtained.
  • FIG. 7 is a module diagram of the CT image generation apparatus 700 of the present embodiment.
  • the CT image generation apparatus 700 includes an X-ray scanner 701, a data interface module 702, an image forming apparatus 703, and a user interface module 704.
  • the X-ray scanner 701 includes an X-ray source and a detector, scans a subject, for example, a human body, obtains projection data, and uses the data as detector data.
  • the data interface module 702 is connected to an interface between the X-ray scanner 701 and the image forming apparatus 703.
  • the user interface module 704 provides functions such as display, printing, and setting to the user.
  • the image forming apparatus 703 reconstructs scan data obtained by the X-ray scanner 701 to form a CT image, and mainly includes a storage module 705, a data bus 706, and a processor module 707.
  • the storage module 705 stores parameters and data, and mainly includes a detector data block 708 for storing projection data scanned by a scanner and projection data generated in an algorithm process, an X-ray source and a detector.
  • a weighting data block 709 for storing weighting vectors calculated based on the geometric relationship with the position of the unit, and the basic geometric parameters of the CT apparatus, for example the relative geometry of the X-ray source and detector
  • a parameter data block 710 for storing the academic position, the size of the monitor unit, and the like, and an output image data block 711 for storing the result image generated by the algorithm are included.
  • the data bus 706 is a data transmission path between the processor module 707 and the storage module 705.
  • the processor module 707 is used for calculation processing of an image reconstruction algorithm, and mainly a main processor 715 for controlling a processing module of an algorithm process for controlling a projection / backprojection angle loop using a geometric parameter;
  • a weighting calculation unit 712 for calculating and generating a weighting vector, which is a feature of the present invention, and a weighting vector multiplication unit for performing a multiplication process of the weighting vector and detector data (detector vector) to obtain a corrected detector value 713 and a separable footprint computation unit 714 that executes a separable footprint projection / backprojection algorithm using the corrected detector values.
  • the CT image generation apparatus 700 can be used when the distance between the X-ray source and the detector does not change with the angle of projection and backprojection. In this case, the CT image generation apparatus 700 performs the test at each angle. An image is formed by irradiating a target, and images obtained at different angles are superimposed. The main processor 715 controls image formation at each angle by a projection / backprojection angle loop.
  • FIGS. 8A and 8B show the operation flow of the projection and backprojection process when the distance between the X-ray source and the detector does not change with the angle of projection and backprojection.
  • a geometric parameter value of CT is acquired (801), and then a weighting vector is calculated (802).
  • the original separable footprint projection operation is first performed for each projection and backprojection angle (803), and then the projection result vector obtained by the projection is weighted and corrected with a weighting vector (804).
  • detector data is first weighted with a weighting vector (805), and a separable footprint backprojection operation is performed on the corrected detector data after weighting (806).
  • the CT image generation apparatus 700 can also be used when the distance between the X-ray source and the detector changes according to the angle of projection and back projection.
  • 9A and 9B show an operational flow diagram of the projection and backprojection process when the relative position of the X-ray source and detector changes. Again, first obtaining the CT geometric parameter value (901) is the same as the operation flow of FIGS. 8A and 8B. However, when the distance between the X-ray source and the detector can change according to the angle of projection and back projection, it is necessary to calculate the weighting vector at each angle based on the change in distance.
  • a weighting vector is calculated based on the geometric parameters at the current projection angle (902), the original separable footprint projection operation is performed (903), and then the projection result vector obtained by the projection is obtained. Weight correction is performed with the weight vector (904), and the above steps 902 to 904 are repeated each time the angle changes.
  • the weighting vector is first calculated by the geometric parameter at the current projection angle (902), and then the detector data is weighted by the weighting vector (905), and the weighted correction is performed.
  • a separable footprint backprojection operation is performed on the detector data (906). Also in this case, the above steps 902, 905 and 906 are repeated every time the angle changes.

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Abstract

La présente invention concerne la réduction d'une erreur entre la projection et la rétroprojection dans la génération d'une image TDM. Le dispositif de génération d'images TDM selon la présente invention est doté de : un dispositif de balayage à rayons X doté d'une source de rayons X et d'un détecteur ; un module de stockage comprenant un bloc données de détecteur, un bloc données de pondération, et un bloc données de paramètres ; et un module de processeur comprenant un processeur principal, une unité de calcul de pondération, une unité de multiplication de vecteur de pondération, une unité de calcul de calcul d'empreinte séparable. Un dispositif de balayage stocke les données de balayage sous la forme de données de détecteur dans le bloc données de détecteur, l'unité de calcul de pondération acquiert un paramètre géométrique du bloc données de paramètres et calcule un vecteur de pondération, et le processeur principal commande une boucle d'angle de projection/rétroprojection en utilisant le paramètre géométrique. L'unité de multiplication du vecteur de pondération multiplie les données de détecteur par un vecteur de pondération et acquiert une valeur de détecteur corrigée, et l'unité de calcul d'empreinte séparable exécute un algorithme de projection/rétroprojection d'empreinte séparable en utilisant la valeur de détecteur corrigée.
PCT/JP2013/082226 2013-02-08 2013-11-29 Dispositif de génération d'images tdm et procédé de génération d'images tdm WO2014122840A1 (fr)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN112790952A (zh) * 2019-11-14 2021-05-14 纬创资通股份有限公司 控制方法以及电动助行器
CN116206007A (zh) * 2023-03-22 2023-06-02 北京朗视仪器股份有限公司 一种cbct图像截断伪影抑制方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106683146B (zh) * 2017-01-11 2021-01-15 上海联影医疗科技股份有限公司 一种图像重建方法和图像重建算法的参数确定方法
WO2019041101A1 (fr) * 2017-08-28 2019-03-07 Shenzhen United Imaging Healthcare Co., Ltd. Systèmes et procédés de détermination d'angles de rotation
CN108492341B (zh) * 2018-02-05 2022-02-25 西安电子科技大学 一种基于像素顶点的平行束投影方法

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US6137856A (en) * 1998-12-14 2000-10-24 General Electric Company Generic architectures for backprojection algorithm
JP2005522304A (ja) * 2002-04-15 2005-07-28 ゼネラル・エレクトリック・カンパニイ 投影法及び逆投影法並びにその実行アルゴリズム
JP2010115475A (ja) * 2008-11-11 2010-05-27 Toshiba Corp コンピュータ断層撮影装置及び方法
JP2010253114A (ja) * 2009-04-27 2010-11-11 Hitachi Ltd 画像再構成方法、ｘ線ｃｔ装置、及びプログラム
WO2012069964A1 (fr) * 2010-11-25 2012-05-31 Koninklijke Philips Electronics N.V. Appareil de projection vers l'avant
JP2012220422A (ja) * 2011-04-12 2012-11-12 Shimadzu Corp 断層像再構成方法およびｘ線ｃｔ装置
WO2013132934A1 (fr) * 2012-03-09 2013-09-12 株式会社日立メディコ Procédé, dispositif et système de génération d'image de ct

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US8913805B2 (en) * 2010-08-30 2014-12-16 The Regents Of The University Of Michigan Three-dimensional forward and back projection methods

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Publication number Priority date Publication date Assignee Title
US6137856A (en) * 1998-12-14 2000-10-24 General Electric Company Generic architectures for backprojection algorithm
JP2005522304A (ja) * 2002-04-15 2005-07-28 ゼネラル・エレクトリック・カンパニイ 投影法及び逆投影法並びにその実行アルゴリズム
JP2010115475A (ja) * 2008-11-11 2010-05-27 Toshiba Corp コンピュータ断層撮影装置及び方法
JP2010253114A (ja) * 2009-04-27 2010-11-11 Hitachi Ltd 画像再構成方法、ｘ線ｃｔ装置、及びプログラム
WO2012069964A1 (fr) * 2010-11-25 2012-05-31 Koninklijke Philips Electronics N.V. Appareil de projection vers l'avant
JP2012220422A (ja) * 2011-04-12 2012-11-12 Shimadzu Corp 断層像再構成方法およびｘ線ｃｔ装置
WO2013132934A1 (fr) * 2012-03-09 2013-09-12 株式会社日立メディコ Procédé, dispositif et système de génération d'image de ct

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112790952A (zh) * 2019-11-14 2021-05-14 纬创资通股份有限公司 控制方法以及电动助行器
CN116206007A (zh) * 2023-03-22 2023-06-02 北京朗视仪器股份有限公司 一种cbct图像截断伪影抑制方法
CN116206007B (zh) * 2023-03-22 2023-09-29 北京朗视仪器股份有限公司 一种cbct图像截断伪影抑制方法

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