WO2020206657A1 - Système d'imagerie par tomodensitométrie multi-énergie et son application - Google Patents

Système d'imagerie par tomodensitométrie multi-énergie et son application Download PDF

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Publication number
WO2020206657A1
WO2020206657A1 PCT/CN2019/082286 CN2019082286W WO2020206657A1 WO 2020206657 A1 WO2020206657 A1 WO 2020206657A1 CN 2019082286 W CN2019082286 W CN 2019082286W WO 2020206657 A1 WO2020206657 A1 WO 2020206657A1
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Prior art keywords
energy
imaging
imaging system
energy spectrum
filter
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PCT/CN2019/082286
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English (en)
Chinese (zh)
Inventor
高河伟
张丽
邢宇翔
陈志强
吴承鹏
刘以农
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清华大学
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Priority to PCT/CN2019/082286 priority Critical patent/WO2020206657A1/fr
Publication of WO2020206657A1 publication Critical patent/WO2020206657A1/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
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]

Definitions

  • the present disclosure belongs to the field of radiation imaging, and relates to a multi-energy CT imaging system and its application, in particular to a multi-energy CT imaging system and its application based on flying focus and energy spectrum filtering.
  • CT Computed Tomography
  • Computed Tomography Computed Tomography
  • Cone-beam CT imaging has broad application prospects in many fields such as industry, agriculture, and medicine. It has already played an indispensable and important role in human oral (dental) examination, image-guided interventional therapy, and radiotherapy.
  • Related imaging Theoretical and applied research has also continued to deepen.
  • Ray scattering is a basic physical challenge that affects the quality of CT images since the birth of CT, which can cause image artifacts and inaccurate CT values.
  • ray scattering exists and is very serious in practical applications.
  • Flat-panel detectors cannot be placed with high-performance de-scattering gratings due to their small pixels. Placing the scatter gratings will cause the detector's ray utilization rate to be too low and the dose loss too large.
  • One of the core issues to improve the imaging performance of cone beam CT is to remove or reduce ray scattering.
  • the methods for removing scattering can be roughly divided into two categories.
  • One is hardware-based direct scattering measurement, such as using scattering occlusion blocks/scattering occlusion bars
  • algorithm-based scattering estimation such as physics-based analysis/Monte Carlo calculations, projection domain convolution filtering, and artifact estimation based on prior images.
  • the direct measurement type scattering correction method has high accuracy, but it has additional requirements on the hardware, and often requires a second scan, which may increase the dose; while the algorithm estimation method has no additional requirements on the hardware, and does not require a second scan, but The correction effect may be worse, or the computational complexity may increase significantly.
  • the present disclosure provides a multi-energy CT imaging system and its application to at least partially solve the technical problems mentioned above.
  • a multi-energy CT imaging system including: a ray source with a flying focus function to generate rays for transmission imaging; an energy spectrum filter for modulating the energy spectrum of incident rays , Including a plurality of filter modules, according to the relative position of each filter module and the focal point of the ray source to generate energy spectrum modulated emitted rays, the emitted rays irradiate the object to be measured; and a detector module for receiving the object to be measured Ray signal.
  • the focal point of a ray source with a flying focus function can move back and forth along the interlayer direction of the detector during CT imaging, or move back and forth along the intralayer direction of the detector, or along The detector moves back and forth in any combination of the two directions between the layers and the layers.
  • the energy spectrum filter is a device relatively fixed to the ray source, and the filter module is made of a material that can change the ray energy spectrum and its spatial distribution. The type, thickness, and distribution of the material determine the energy The energy spectrum distribution of the emitted rays after spectrum modulation.
  • the focus of the flying focus ray source moves back and forth, which occurs during the data collection process of all projection angles of CT imaging, so that the focus positions of data collection at adjacent projection angles are different; or, The focus of the flying focus ray source moves back and forth during the data collection process of the CT imaging part of the projection angle, so that only the focus position of the data collection under the partial projection angle changes.
  • the multiple filter modules of the energy spectrum filter are semi-transparent module units that attenuate part of the rays, and the multiple filter modules are periodically distributed.
  • the multiple filter modules include two or more filter grids or filter bars of different thicknesses or materials.
  • the ray source with the flying focus function includes one of the following devices: X-ray tubes, carbon nanotubes, or accelerators.
  • the rays used for transmission imaging are X-rays or gamma rays.
  • the multi-energy CT imaging system further includes: a mechanical/electrical control module for mechanical and/or electrical control of the movement of the focus position of the ray source; a data transmission unit for controlling the detector The ray signal received by the module performs data transmission; and a data processing unit is used for data processing.
  • an application of a multi-energy CT imaging system in the field of multi-energy CT imaging is provided.
  • a ray source with flying focus function combined with an energy spectrum modulation method and a static spatial energy spectrum filter, it can quickly switch to generate different ray energy spectra to realize multi-energy CT imaging, and at the same time, it can improve the CT detector layer (Z direction) Sampling rate and/or intra-layer (X-direction) sampling rate to obtain non-sparse multi-energy CT data, which can then carry out more accurate decomposition of base materials and adopt faster and more convenient analytical reconstruction methods. It has Good application prospects.
  • Fig. 1 is a simplified schematic diagram of a planar structure of a multi-energy CT imaging system according to an embodiment of the present disclosure.
  • Fig. 2 is a schematic diagram of a three-dimensional structure of a multi-energy CT imaging system according to an embodiment of the present disclosure.
  • Fig. 3 is a schematic diagram of the function of a ray source flying focus in a multi-energy CT imaging system according to an embodiment of the disclosure.
  • FIG. 4 is a schematic diagram of the energy spectrum filter of the multi-energy CT imaging system according to an embodiment of the present disclosure modulating the energy spectrum of the incident rays, and generating rays of different energy spectra according to the relative position of the focus of the ray source, wherein, (a) is a schematic diagram of incident rays containing multiple energy spectra, (c) is a schematic diagram of energy spectrum distribution corresponding to incident rays; (b) is a schematic diagram of emitted rays modulated by an energy spectrum filter, (d) is a The schematic diagram of the energy spectrum distribution corresponding to the ray; (e) is the schematic diagram of the material distribution of the energy spectrum filter.
  • Source modulation scattering correction has been developed in the past 10 years. Its basic principle is to place a high-frequency translucent attenuation grid between the X-ray source and the scanned object, and pass a series of physical assumptions (mainly scattered photon distribution). The low-frequency characteristics) and mathematical derivation to achieve fast scatter correction requiring only one CT scan measurement. In recent years, source modulation scatter correction has been further developed, especially in scatter estimation algorithms. The main difficulty of source modulation scattering correction is that the modulator will introduce ray hardening and energy spectrum inconsistency, which may limit the performance of scattering correction in practical applications.
  • Dynamic spatial energy spectrum filtering can realize cone-beam CT multi-energy imaging, but it needs more complicated mechanical and electrical control to realize the movement of energy spectrum filter, there is a problem of sparse data, and it is difficult to decompose the base material.
  • source modulation extend the source modulation method to cone-beam CT dual-energy imaging, but it also has the problem of sparse data and requires iterative reconstruction methods.
  • the ray source flying focus technology has been successfully applied to high-end medical diagnostic CT machines. It increases the sampling rate between layers (Z direction) or intralayer (X direction) of the CT detector by changing the position where the electron beam bombards the tungsten target during the generation of the X-ray source, that is, the focus position of the X-ray source.
  • the present disclosure innovatively uses the ray source flying focus technology, combines the energy spectrum modulation scattering correction theory, and the static spatial energy spectrum filtering method to establish a brand-new multi-energy CT imaging system to realize non-sparse multi-energy CT data and single energy Multi-energy CT imaging system with ray source and static energy spectrum filtering.
  • A/B means A and/or B.
  • a data transmission/processing unit includes a data transmission unit or a data processing unit, or the unit has both data transmission and processing functions.
  • a multi-energy CT imaging system is provided.
  • Fig. 1 is a simplified schematic diagram of a planar structure of a multi-energy CT imaging system according to an embodiment of the present disclosure.
  • Fig. 2 is a schematic diagram of a three-dimensional structure of a multi-energy CT imaging system according to an embodiment of the present disclosure.
  • the multi-energy CT imaging system of the present disclosure includes: a ray source with a flying focus function to generate rays for transmission imaging; an energy spectrum filter for performing the energy spectrum of incident rays Modulation, including multiple filter modules, according to the relative position of each filter module and the focal point of the ray source to generate energy spectrum modulated emitted rays, which irradiate the object to be measured; and a detector module for receiving the object to be measured Ray signal.
  • the multi-energy CT imaging system further includes: a mechanical/electrical control module, which is used to mechanically and/or electrically control the movement of the focal position of the radiation source.
  • the multi-energy CT imaging system further includes: a data transmission unit for data transmission of the radiation signal received by the detector module. Furthermore, it also includes: a data processing unit for data processing.
  • the data transmission unit and the data processing unit may be integrated in the same module, or may be separate units.
  • the multi-energy CT imaging system in this embodiment includes: a ray source, an energy spectrum filter, a detector module, a mechanical/electrical control and a data transmission/processing unit.
  • the ray source is a ray source with a flying focus function, which can be one of X-ray tubes, carbon nanotubes and accelerators, which can generate rays for transmission imaging; the rays are X-rays or Gamma rays. Horse ray; the focus of the ray source can move along the interlayer (Z direction shown in Figure 3) and/or within the layer (X direction shown in Figure 3) or two directions successively to change the initial position of the ray emitted by the ray source .
  • the ray source can rotate 360 degrees around the object to be measured, as shown by the circular dashed line in the figure, so as to scan all angles of the object to be measured.
  • Fig. 3 is a schematic diagram of the function of a ray source flying focus in a multi-energy CT imaging system according to an embodiment of the present disclosure.
  • the focus of the ray source is initially at the center point, the focus can be quickly switched to the upper and lower points in the Z direction, or the left and right points in the X direction, or the four points in the diagonal direction through electrical control operations. Place.
  • the fly-focus function of the ray source is used to make the focal point of the ray source move as required, so as to realize the regulation of the initial position of the ray emitted by the ray source.
  • the flying focus function for sampling at every angle.
  • the frequency of the flying focus can be determined according to actual needs.
  • the sparse flying focus adopting mode is used, that is, a flying focus sampling is done every few angles.
  • the focus of the flying focus ray source moves back and forth, which occurs during the data collection process of all projection angles of CT imaging, so that the focus positions of data collection at adjacent projection angles are different; or, The focus of the flying focus ray source moves back and forth during the data collection process of the CT imaging part of the projection angle, so that only the focus position of the data collection under the partial projection angle changes.
  • the plurality of filter modules of the energy spectrum filter are semi-transparent module units that attenuate part of the rays, and the plurality of filter modules are arranged in a periodic distribution form, for example, the plurality of filter modules are arranged in a high frequency period. Sexual grid-like.
  • the multiple filter modules include two or more filter grids or filter bars of different thicknesses or materials.
  • the energy spectrum filter is a device relatively fixed to the ray source, and the filter module is made of a material that can change the ray energy spectrum and its spatial distribution, and the type, thickness and distribution of the material are determined The energy spectrum distribution of the emitted rays after energy spectrum modulation.
  • the energy spectrum filter is a device relatively fixed to the ray source, and a plurality of filter modules are made of materials that can absorb part of the rays, and are processed into translucent module units, arranged in a high-frequency periodic grid.
  • the incident ray energy spectrum is modulated, and rays of different energy spectrum are generated according to the relative position of the filter module and the focus of the ray source.
  • the ray energy spectrum or energy spectrum distribution represents the quantity distribution formed by rays of different energy.
  • FIG. 4 is a schematic diagram of the energy spectrum filter of the multi-energy CT imaging system according to an embodiment of the present disclosure modulating the energy spectrum of the incident rays, and generating rays of different energy spectra according to the relative position of the focus of the ray source, wherein, (a) is a schematic diagram of incident rays containing multiple energy spectra, (c) is a schematic diagram of the energy spectrum distribution corresponding to the incident rays, the ordinate is normalized; (b) is the outgoing ray modulated by an energy spectrum filter In the schematic diagram, (d) is the schematic diagram of the energy spectrum distribution corresponding to the emitted rays, and the ordinate is normalized; (e) is the schematic diagram of the material distribution of the energy spectrum filter.
  • Figure 4 it is assumed that three different energy spectra need to be generated through an energy spectrum filter, and the corresponding energy spectrum filter is composed of three different types of materials with different thicknesses, which are respectively material 1, material 2. And material 3 are arranged at intervals in order to form a high-frequency periodic grid, as shown in Figure 4 (e), which can modulate the energy spectrum of incident rays.
  • the incident rays are shown in Figure 4 (a). Parallel lines at the same starting position indicate rays of the same energy.
  • Figure 4(a) illustrates incident rays of multiple energies, such as three energies.
  • the energy spectrum distribution diagrams of these three energies are shown in Figure 4(c) ) Means; after the incident rays containing multiple energies are modulated by energy spectrum filters arranged in a high-frequency periodic grid, the outgoing rays are generated according to the relative position of the focus of the ray source.
  • the outgoing rays are shown in Figure 4 ( As shown in b), compared with the incident ray shown in Fig. 4(a), each energy value and the distribution of each energy value have changed.
  • the energy spectrum distribution diagram of the outgoing ray is shown in Fig. 4(d) , So as to achieve energy spectrum modulation, and then change the energy spectrum of rays passing through the object.
  • the material type, thickness, and arrangement manner of the corresponding energy spectrum filter can be designed according to system design requirements, and it is not limited to the material type, thickness and arrangement manner in this embodiment.
  • Multi-energy CT-based material decomposition method Based on the multi-energy CT system, combined with the patent application "Multi-energy CT-based material decomposition method" filed by the applicant on the same day, CT imaging without artifacts can be realized. Based on the multi-energy CT system, it can quickly switch to generate different ray energy spectra, realize multi-energy CT imaging, and at the same time, it can increase the sampling rate between the CT detector layers (Z direction) and/or the intra-layer (X direction) sampling rate to obtain non- Sparse multi-energy CT data, and then more accurate decomposition of the base material; by adding the scattering intensity under the corresponding energy spectrum to the energy spectrum projection value under multi-energy, the relationship between the scattering intensity under different energy is calibrated , The scattering distribution correlation function is obtained.
  • the weighted coefficient projection value and the scattering intensity distribution of the two base materials can be calculated through the pre-established mapping model. According to the actual measured projection value, based on the pre-established two-way mapping relationship, Then the projection value can be decomposed to M base materials, and the projection data and scattering intensity of the M base materials corresponding to the unknown object structure can be found. Since the scattering intensity and the projection data of the M base materials are separated, Elimination of artifacts, image reconstruction only based on the projection data of a variety of base materials, images without artifacts can be obtained, with a very good effect of eliminating artifacts, has a good application in the field of multi-energy CT imaging prospect.
  • the present disclosure provides a multi-energy CT imaging system and its application.
  • a ray source with flying focus function combined with a source modulation method and static spatial energy spectrum filtering, it can quickly switch to generate different ray energy spectra.
  • To achieve multi-energy CT imaging and at the same time to obtain non-sparse multi-energy CT data by increasing the inter-layer (Z-direction) sampling rate and/or the intra-layer (X-direction) sampling rate of the CT detector, thereby enabling more accurate base materials
  • Material decomposition and the use of faster and more convenient analytical reconstruction methods have good application prospects in the field of multi-energy CT imaging. Based on this multi-energy CT imaging system, CT imaging without artifacts can be realized.

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Abstract

La présente invention concerne un système d'imagerie par tomodensitométrie multi-énergie et son application. Le système d'imagerie par tomodensitométrie multi-énergie comprend : une source de rayons de rayonnement ayant une fonction de point focal volant et générant un rayon de rayonnement utilisé pour une imagerie de transmission ; un filtre de spectre d'énergie comprenant de multiples modules de filtre, utilisés pour moduler un spectre d'énergie d'un rayon de rayonnement incident, et générer un rayon de rayonnement émergent modulé par spectre d'énergie selon des positions relatives respectives de chaque module de filtre par rapport à un point focal de la source de rayons de rayonnement, le rayon de rayonnement émergent exposant au rayonnement un objet à l'essai ; et un module de détecteur utilisé pour recevoir un signal de rayon de rayonnement ayant traversé l'objet à l'essai. La présente invention utilise la source de rayons de rayonnement ayant la fonction de point focal volant, et combine un procédé de modulation de spectre d'énergie et un filtrage de spectre d'énergie spatiale statique, ce qui permet une commutation rapide entre différents spectres d'énergie de rayons de rayonnement, et permet de réaliser une imagerie par tomodensitométrie multi-énergie. De plus, la présente invention acquiert des données de tomodensitométrie multi-énergie non éparses par amélioration d'un taux d'échantillonnage inter-couche et/ou d'un taux d'échantillonnage intra-couche d'un tomodensitomètre, et effectue une décomposition matérielle précise de matériaux de base en conséquence, fournissant ainsi des perspectives d'application prometteuses dans le domaine de l'imagerie par tomodensitométrie multi-énergie.
PCT/CN2019/082286 2019-04-11 2019-04-11 Système d'imagerie par tomodensitométrie multi-énergie et son application WO2020206657A1 (fr)

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CN102727230A (zh) * 2011-04-02 2012-10-17 沈阳东软医疗系统有限公司 Ct扫描图像重建方法及装置
US8862206B2 (en) * 2009-11-12 2014-10-14 Virginia Tech Intellectual Properties, Inc. Extended interior methods and systems for spectral, optical, and photoacoustic imaging
US9220469B2 (en) * 2013-12-31 2015-12-29 General Electric Company Systems and methods for correcting detector errors in computed tomography imaging
CN106361367A (zh) * 2016-12-01 2017-02-01 上海联影医疗科技有限公司 一种检测器的校正方法和使用该校正方法的装置及设备

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7400703B2 (en) * 2006-08-11 2008-07-15 General Electric Company Method and system for controlling radiation intensity of an imaging system
US8862206B2 (en) * 2009-11-12 2014-10-14 Virginia Tech Intellectual Properties, Inc. Extended interior methods and systems for spectral, optical, and photoacoustic imaging
CN102727231A (zh) * 2011-04-02 2012-10-17 沈阳东软医疗系统有限公司 飞焦点ct机扫描数据采集方法及装置
CN102727230A (zh) * 2011-04-02 2012-10-17 沈阳东软医疗系统有限公司 Ct扫描图像重建方法及装置
US9220469B2 (en) * 2013-12-31 2015-12-29 General Electric Company Systems and methods for correcting detector errors in computed tomography imaging
CN106361367A (zh) * 2016-12-01 2017-02-01 上海联影医疗科技有限公司 一种检测器的校正方法和使用该校正方法的装置及设备

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