Static CT imaging device with tube current modulation function and imaging method thereof

Abstract

A static CT imaging device with a tube current modulation function and an imaging method therefor are provided. [Solution] The static CT imaging device of the present invention includes a radiation source ring and a detector ring. The radiation source ring is provided with a plurality of uniformly distributed radiation sources, each of which emits radiation to scan the human body to be measured and projects positioning images of the human body at different angles onto the detector ring. The detector ring is provided with a plurality of uniformly distributed detectors for collecting radiation and obtaining positioning images. Based on the projection brightness of the positioning image, tube current modulation information of the radiation sources corresponding to the corresponding projection positions is obtained, where the tube current modulation information includes the tube current value to be used by each radiation source on the radiation source ring during the medical examination. The tube current of the corresponding radiation source on the radiation source ring is adjusted based on the tube current modulation information. By realizing automatic tube current modulation, the present invention can effectively reduce the exposure dose to the human body.

Description

[Technical Field]

[0001] The present invention relates to a static CT imaging device with tube current modulation function, which belongs to the field of medical equipment technology, and to a corresponding static CT imaging method. [Background technology]

[0002] CT (Computed Tomography) is a type of imaging technology. It uses an X-ray beam and a highly sensitive X-ray detector to scan a specific area of ​​the human body, layer by layer. The X-rays that pass through the X-ray detector are received by a scintillating material, converted into visible light, then converted into an electrical signal by a photoelectric converter, amplified, and then converted into a digital signal by analog-to-digital conversion, which is then input into a computer for processing. The computer calculates the information obtained from the layer-by-layer scan, obtains the X-ray attenuation or absorption coefficient of each voxel, and arranges it into a matrix, known as a voxel digital matrix. The digital information in the voxel digital matrix is ​​converted into small blocks of varying shades of black to white, called pixels in a two-dimensional projection, which are arranged in a tomographic fashion to form a CT image.

[0003] To increase scanning speed, improve imaging accuracy and speed, avoid the effects of centrifugal force caused by mechanical rotation, and reduce the signal tailing and overlapping crosstalk caused by high-speed rotation, a static real-time CT imaging system is disclosed in a Chinese invention patent with publication number CN105361900B. This static real-time CT imaging system includes an annular photon counting detector, an annular scanning X-ray source, and a scan timing controller. Under the control of the scan timing controller, the annular scanning X-ray source emits a narrow beam of X-rays, which passes through the object to be measured and is projected onto the corresponding annular photon counting detector. The annular photon counting detector transmits the corresponding exposure information to a data acquisition and processing unit and a human-computer interaction unit via a scanning host and a main control unit, where the data acquisition and processing unit and the human-computer interaction unit complete image reconstruction. During the scanning process of the static real-time CT imaging system, the circular scanning X-ray source does not need to rotate significantly. Instead, the X-ray projection position is switched sequentially through electronic control, which increases the scanning speed by several tens of times and enables dynamic 3D stereoscopic images to be obtained. The photon counting detector can obtain absorption data and energy data, thereby realizing real-time data reconstruction.

[0004] However, during medical examinations using CT equipment, it is necessary to control the radiation dose to reduce harm to the human body. Most spiral CT devices have only one radiation source, so in the most extreme case (chest scan), two cycles of tube current adjustment are required per scan. Four scans per second requires a tube current adjustment frequency of approximately 8 Hz. For hot cathode radiation sources, the magnitude of the tube current is significantly affected by the ambient temperature and filament temperature, making tube current modulation technically challenging. Summary of the Invention [Problem to be solved by the invention]

[0005] The main technical problem that the present invention aims to solve is to provide a static CT imaging device with tube current modulation capability.

[0006] Another technical problem that the present invention aims to solve is to provide a corresponding static CT imaging method.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] According to a first aspect of an embodiment of the present invention, a radiation source ring and a detector ring are included, a plurality of uniformly distributed radiation sources are provided in the radiation source ring, each of the radiation sources is used to emit radiation for scanning a human body to be measured and to project positioning images of the human body at different angles onto the detector ring, and a plurality of uniformly distributed detectors are provided in the detector ring to collect the radiation and obtain the positioning images; Obtain tube current modulation information of the radiation sources corresponding to the corresponding projection positions according to the projection brightness of the positioning image, the tube current modulation information including a value of a tube current to be used by each of the radiation sources on the radiation source ring during a medical examination; A static CT imaging device with a tube current modulation function is provided, which adjusts the tube current of the corresponding radiation source on the radiation source ring based on the tube current modulation information.

[0009] Preferably, a 0-degree tube current to be used by a radiation source at a 0-degree position in the radiation source ring during a medical examination is obtained based on the projection brightness of the positioning image; Determine a body thickness and a body coverage area in the XY direction of the positioning image based on a bed height, and obtain a 90-degree tube current to be used by a radiation source at a 90-degree position in the radiation source ring during a medical examination; According to the principle of symmetry, a 180-degree tube current is obtained based on the 0-degree tube current, and a 270-degree tube current is obtained based on the 90-degree tube current; An interpolation method is used to interpolate the 0 degree tube current, the 90 degree tube current, the 180 degree tube current, and the 270 degree tube current to obtain the tube current to be used by the radiation source at each position in the radiation source ring during a medical examination.

[0010] Preferably, the radiation sources emit radiation alternately at a set frequency, and the projection areas corresponding to the radiation sources do not overlap.

[0011] The static CT imaging device further includes an image processing device, which is connected to the detector ring and is used to receive the positioning image and perform image processing on the positioning image.

[0012] Preferably, the interpolation method uses a linear interpolation method or an elliptical interpolation method.

[0013] According to a second aspect of an embodiment of the present invention, there is provided a static CT imaging method implemented on the basis of the static CT imaging device described above, the method comprising: each radiation source in the radiation source ring emits radiation for scanning a human body to be measured, and a detector in the detector ring acquires positioning images of the human body at different angles by projecting the positioning images onto the detector ring; obtaining tube current modulation information of the radiation sources corresponding to corresponding projection positions based on the projection brightness of the positioning images, the tube current modulation information including a value of a tube current to be used by each of the radiation sources on the radiation source ring during a medical examination; and adjusting the tube current of the corresponding radiation source on the radiation source ring based on the tube current modulation information.

[0014] Preferably, a 0-degree tube current to be used by a radiation source at a 0-degree position in the radiation source ring during a medical examination is obtained based on the projection brightness of the positioning image; Determine a body thickness and a body coverage area in the XY direction of the positioning image based on a bed height, and obtain a 90-degree tube current to be used by a radiation source at a 90-degree position in the radiation source ring during a medical examination; According to the principle of symmetry, a 180-degree tube current is obtained based on the 0-degree tube current, and a 270-degree tube current is obtained based on the 90-degree tube current; An interpolation method is used to interpolate between the 0 degree tube current, the 90 degree tube current, the 180 degree tube current, and the 270 degree tube current to obtain the tube current to be used by the radiation source at each position in the radiation source ring during a medical examination.

[0015] Preferably, the value of the tube current is related to the body thickness. [Effects of the Invention]

[0016] Compared with the prior art, the static CT imaging device with tube current modulation function provided by the present invention sets the tube current of the radiation source corresponding to the projection angle to a value associated with the thickness of the human body according to the different conditions of the radiation passing through the thickness of the human body at different projection angles, thereby realizing automatic modulation of the tube current and effectively reducing the radiation dose to the human body. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing the overall structure of a static CT imaging device with tube current modulation function according to an embodiment of the present invention; [Figure 2] 2 is a schematic diagram illustrating the distribution of radiation sources in a static CT imaging device according to one embodiment of the present invention. [Figure 3] FIG. 4 is a schematic diagram showing tube currents corresponding to projection angles in an embodiment of the present invention. [Figure 4] FIG. 2 is a flowchart illustrating a method for static CT imaging with tube current modulation according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The technical contents of the present invention will be described in detail and specifically below in combination with the accompanying drawings and specific embodiments.

[0019] In the process of performing medical examinations using CT devices, automatic tube current modulation, which automatically adjusts the value of the tube current used during scanning based on the positioning image, is one of the important technologies for controlling the radiation dose. However, existing spiral CT devices have only one radiation source, making it technically difficult to achieve tube current modulation.

[0020] As shown in Figure 1, a static CT imaging device has multiple radiation sources uniformly distributed across the entire ring, so the concept behind automatic tube current modulation technology is completely different from that of a spiral CT device. A static CT imaging device does not need to adjust the tube current of a single radiation source in real time. Instead, it only needs to calculate and set the tube current of the radiation source at a specific projection angle according to the relationship between the tube current and the projection angle. Before scanning, the pre-calculated tube current modulation methods for various angular positions are set for the radiation source at the corresponding angular position, and the static CT imaging device can scan according to the set tube current modulation method.

[0021] Therefore, by combining the unique characteristics of the radiation source ring and detector ring of the static CT imaging device, a unique automatic tube current modulation function can be realized. That is, according to the different conditions of X-rays passing through the thickness of the human body at different projection angles, the tube current of the radiation source corresponding to the projection angle can be set to a value related to the thickness of the human body, thereby realizing "automatic tube current modulation" and effectively reducing the radiation dose to the human body.

[0022] It should be noted that in the art, the intensity of X-rays is usually expressed in milliamperes (mA) of tube current. By controlling the value of the tube current, the brightness of the projection image (such as a positioning image) can be controlled. Furthermore, the 0-degree position referred to in the embodiments of the present invention refers to the position directly above the radiation source ring and / or the detector ring, and the corresponding angular position is calculated according to the counterclockwise direction.

[0023] An embodiment of the present invention first provides a static CT imaging device with a tube current modulation function. The core idea of ​​this static CT imaging device is to utilize the unique characteristics of the radiation source ring and detector ring of the static CT imaging device to calculate and set the tube current value required for the radiation source at a specific projection angle according to the relationship between the tube current and the projection angle. Before scanning, the pre-calculated tube current modulation method for each angle position is set to the radiation source at the corresponding angle position, and then scanning is performed according to the set tube current value.

[0024] A specific embodiment of the static CT imaging device with the tube current modulation function will be described in detail below in combination with the examples shown in FIGS.

[0025] As shown in FIG. 2, a static CT imaging device with tube current modulation function includes a radiation source ring and a detector ring. The radiation source ring includes a plurality of uniformly distributed radiation sources, each of which emits radiation to scan a human body to be measured and projects positioning images of the human body at different angles onto the detector ring. The detector ring includes a plurality of uniformly distributed detectors for collecting the radiation and obtaining the positioning images. Based on the projection brightness of the positioning images, tube current modulation information of the radiation sources corresponding to corresponding projection positions is obtained, where the tube current modulation information includes a tube current value to be used by each radiation source on the radiation source ring during a medical examination. The tube current of the corresponding radiation source on the radiation source ring is adjusted based on the tube current modulation information.

[0026] In one embodiment of the present invention, the radiation source is preferably an X-ray source, but may be other types of radiation source. A positioning image of the human body is acquired by scanning using the radiation source at the 0 degree position, and a 0 degree tube current mA-0 to be used by the radiation source at the 0 degree position in the radiation source ring during the medical examination is acquired based on the projection brightness of the positioning image.

[0027] Determine the thickness of the human body and the coverage of the human body in the XY direction of the positioning image based on the height of the bed, and obtain a 90-degree tube current mA-90 that should be used by the radiation source at the 90-degree position in the radiation source ring during the medical examination; According to the principle of symmetry, the 180-degree tube current mA-180 is obtained based on the 0-degree tube current, and the value of mA-180 is equal to the value of mA-0. The 270-degree tube current mA-270 is obtained based on the 90-degree tube current, and the value of mA-270 is equal to the value of mA-90. Specifically, considering the inherent symmetry of the human body, mA-0, mA-90, mA-180, and mA-270 are set as four end points, and the tube currents at different projection angles exhibit axial symmetry and circular symmetry.

[0028] Therefore, the tube current corresponding to the projection angle as shown in FIG. 3 is obtained by interpolating between the 0-degree tube current, the 90-degree tube current, the 180-degree tube current, and the 270-degree tube current using an interpolation method to obtain the tube current to be used by the radiation source at each angle position in the radiation source ring during a medical examination.

[0029] In addition to the linear interpolation method mentioned above, other interpolation methods can also be used. For example, the human body is simulated as an ellipse, and 0 and 90 degrees correspond to the minor and major axes of the ellipse, respectively. By calculating the path of the radiation passing through this ellipse at different projection angles, the tube current mA-X (X represents the angle) of the radiation source corresponding to each projection angle can be obtained.

[0030] After the tube current settings of the radiation sources at different projection angles are completed, a normal scanning process is started, and each radiation source located at a different projection angle of the radiation source ring performs a medical examination with a different tube current.

[0031] In one embodiment of the present invention, a plurality of radiation sources (e.g., four, six, or eight) may be evenly arranged in a radiation source ring, and each radiation source alternately emits radiation at a set frequency, but the alternating frequency of the emitted radiation should be such that the projection areas corresponding to each radiation source do not overlap to avoid interference.

[0032] In one embodiment of the present invention, the static CT imaging device may further include an image processing device connected to the detector ring and used for receiving the positioning image and performing image processing for the positioning.

[0033] Based on the above static CT imaging device, as shown in FIG. 4, an embodiment of the present invention further provides a static CT imaging method with tube current modulation function, specifically including steps S1 to S3. S1: Each radiation source in the radiation source ring emits radiation to scan the human body to be measured, and projects positioning images of the human body at different angles onto the detector ring, so that the detectors on the detector ring obtain the positioning images. S2: A step of obtaining tube current modulation information of the radiation source corresponding to the projection position based on the projection brightness of the positioning image of the human body, wherein the tube current modulation information includes a value of a tube current to be used by each of the radiation sources on the radiation source ring during a medical examination. S3: Adjusting the tube current of the corresponding radiation source on the radiation source ring based on the tube current modulation information.

[0034] Specifically, a positioning image of the human body is obtained by scanning with a radiation source at a 0 degree position, and a 0 degree tube current mA-0 to be used by the radiation source at the 0 degree position in the radiation source ring during a medical examination is obtained according to the projection brightness of the positioning image; Determine the thickness of the human body and the coverage of the human body in the XY direction of the positioning image based on the height of the bed, and obtain a 90-degree tube current mA-90 that should be used by the radiation source at the 90-degree position in the radiation source ring during the medical examination; According to the principle of symmetry of the human body, the 180-degree tube current mA-180 is obtained based on the 0-degree tube current, and the value of mA-180 is equal to the value of mA-0, and the 270-degree tube current mA-270 is obtained based on the 90-degree tube current, and the value of mA-270 is equal to the value of mA-90. That is, considering the inherent symmetry of the human body, mA-0, mA-90, mA-180, and mA-270 are set as the four end points, and the tube currents at different projection angles exhibit axial symmetry and circular symmetry.

[0035] Therefore, by using an interpolation method to interpolate between the 0 degree tube current, the 90 degree tube current, the 180 degree tube current, and the 270 degree tube current, the tube current to be used by the radiation source at each angular position in the radiation source ring during a medical examination is obtained. In different embodiments of the present invention, the interpolation method may be a linear interpolation method or an elliptical interpolation method.

[0036] Since the tube current value is related to the thickness of the human body, the tube current value related to the thickness of the human body is set to the corresponding radiation source on the radiation source ring. After the tube current setting of the radiation sources at different projection angles is completed, the normal scanning process is started. Each radiation source at different projection angles of the radiation source ring performs medical examination work with a different tube current.

[0037] Compared with the prior art, the static CT imaging device with tube current modulation function and imaging method provided by the present invention can set the tube current of the radiation source corresponding to the projection angle to a value associated with the thickness of the human body according to the situation where the thickness through which radiation passes through the human body varies at different projection angles, thereby realizing automatic modulation of the tube current and effectively reducing the radiation dose to the human body.

[0038] The static CT imaging device with tube current modulation function and the imaging method thereof provided by the present invention have been described in detail above. Any obvious modifications made to the present invention by those skilled in the art without departing from the essential content of the present invention will be considered as an infringement of the patent right of the present invention and will incur corresponding legal liability.

Claims

1. A static CT imaging device with tube current modulation, comprising: a radiation source ring and a detector ring; a plurality of uniformly distributed radiation sources are provided in the radiation source ring, each of the radiation sources is used to emit radiation for scanning a human body to be measured and to project positioning images of the human body at different angles onto the detector ring, and a plurality of uniformly distributed detectors are provided in the detector ring to collect the radiation and obtain the positioning images; Obtain tube current modulation information of the radiation sources corresponding to the corresponding projection positions according to the projection brightness of the positioning image, the tube current modulation information including a value of a tube current to be used by each of the radiation sources on the radiation source ring during a medical examination; A static CT imaging device with a tube current modulation function, characterized in that the tube current of a corresponding radiation source on the radiation source ring is adjusted based on the tube current modulation information.

2. obtaining a 0-degree tube current to be used by a radiation source at a 0-degree position in the radiation source ring during a medical examination based on the projection brightness of the positioning image; Determine a body thickness and a body coverage area in the X-Y direction of the positioning image based on a bed height, and obtain a 90-degree tube current to be used by a radiation source at a 90-degree position in the radiation source ring during a medical examination; The static CT imaging device with tube current modulation function according to claim 1, characterized in that, according to the principle of symmetry, a 180-degree tube current is obtained based on the 0-degree tube current, and a 270-degree tube current is obtained based on the 90-degree tube current.

3. 3. The static CT imaging device with tube current modulation function according to claim 2, wherein an interpolation method is used to interpolate between the 0-degree tube current, the 90-degree tube current, the 180-degree tube current, and the 270-degree tube current, thereby obtaining the tube current to be used by the radiation source at each position in the radiation source ring during a medical examination.

4. 4. The static CT imaging device with tube current modulation function according to claim 3, wherein the interpolation method is a linear interpolation method or an elliptical interpolation method.

5. 2. The static CT imaging device with tube current modulation function according to claim 1, wherein each of the radiation sources alternately emits radiation at a set frequency, and projection areas corresponding to each of the radiation sources do not overlap.

6. 2. The static CT imaging device with tube current modulation function according to claim 1, further comprising an image processing device connected to the detector ring and used to receive the positioning image and perform image processing on the positioning image.

7. A static CT imaging method implemented on the basis of a static CT imaging device according to any one of claims 1 to 6, comprising: each radiation source in the radiation source ring emits radiation to scan the human body to be measured, and projects positioning images of the human body at different angles onto the detector ring, so that detectors on the detector ring acquire the positioning images; obtaining tube current modulation information of the radiation sources corresponding to corresponding projection positions based on the projection brightness of the positioning images, the tube current modulation information including a value of a tube current to be used by each of the radiation sources on the radiation source ring during a medical examination; and adjusting the tube currents of the corresponding radiation sources on the radiation source ring based on the tube current modulation information.

8. obtaining a 0-degree tube current to be used by a radiation source at a 0-degree position in the radiation source ring during a medical examination based on the projection brightness of the positioning image; Determine a body thickness and a body coverage area in the X-Y direction of the positioning image based on a bed height, and obtain a 90-degree tube current to be used by a radiation source at a 90-degree position in the radiation source ring during a medical examination; According to the principle of symmetry, a 180-degree tube current is obtained based on the 0-degree tube current, and a 270-degree tube current is obtained based on the 90-degree tube current; 8. The static CT imaging method of claim 7, wherein an interpolation method is used to interpolate between the 0-degree tube current, the 90-degree tube current, the 180-degree tube current, and the 270-degree tube current to obtain the tube current to be used by the radiation source at each angle in the radiation source ring during a medical examination.

9. 9. The static CT imaging method according to claim 8, wherein the interpolation method is a linear interpolation method or an elliptical interpolation method.

10. The static CT imaging method according to any one of claims 7 to 9, wherein the value of the tube current is associated with the thickness of the human body.

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