CN104665859B - Imaging system - Google Patents

Abstract

The present invention relates to an imaging system. The imaging system comprises: an X-ray source for emitting a beam of X-rays; a detector array comprising a plurality of detectors which generate an initial signal responsive to the beam of X-rays obliquely incident on the detectors, the The initial signal includes a parallax crosstalk signal in response to an X-ray beam incident to the adjacent detector; and a correction module, connected to the detector array, and used to correct the parallax crosstalk signal from the adjacent detector to generate a correction Signal. The imaging system corrects the parallax crosstalk signal to improve image quality.

Description

imaging system

technical field

The present invention relates to an imaging system, in particular to an imaging system used in CT (Computed Tomography, computerized tomography) imaging.

Background technique

CT scanners work by projecting a fan-shaped or cone-shaped beam of X-rays from an X-ray source. The X-ray source emits X-rays at multiple viewing positions around an imaged object, such as a patient, which attenuates the X-ray beam as it passes through it. The attenuated beam is detected by a set of detectors which generate a signal representative of the intensity of the incident X-ray beam. Processing the signal yields data representing the line integral of the object's attenuation coefficient along the x-ray path. These signals are generally referred to as "projection data" or simply "projections". Useful images can be formed from the projections using reconstruction techniques, such as filtered backprojection. The images can then be correlated to form a volumetric rendering of the region of interest. In medicine, various pathologies or other structures of interest can then be located or identified from the reconstructed image or reconstructed volume. It is generally desirable to develop a CT scanner with high spatial and temporal resolution and good image quality. When X-ray beams are injected into multiple detectors, parallax crosstalk signals will be generated. Parallax crosstalk is an important cause of image quality degradation, and image noise and artifacts will be generated.

Therefore, it is necessary to provide an imaging system to solve the technical problems mentioned above.

Contents of the invention

One aspect of the present invention is to provide an imaging system. The imaging system includes: an X-ray source for emitting an X-ray beam; a detector array including a plurality of detectors that generate an initial signal responsive to an X-ray beam obliquely incident on the detector, the The initial signal includes a parallax crosstalk signal in response to the X-ray beam incident to the adjacent detector; and a correction module, connected to the detector array, and used to correct the parallax crosstalk signal from the adjacent detector to generate a correction Signal.

The imaging system of the present invention corrects the parallax crosstalk signal to improve image quality.

Description of drawings

By describing the embodiments of the present invention in conjunction with the accompanying drawings, the present invention can be better understood. In the accompanying drawings:

Fig. 1 shows the schematic diagram of an embodiment of the imaging system of the present invention;

Figure 2 is a schematic diagram of an embodiment of an X-ray source and detector array of the imaging system shown in Figure 1;

Fig. 3 is a partial schematic view of a panel module of a detection array of an embodiment;

FIG. 4 is a partial schematic view of a panel module of a detection array in another embodiment;

FIG. 5 is a partial schematic diagram of a flat panel module of a detection array according to another embodiment.

detailed description

Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by those skilled in the art to which the present invention belongs. "First", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any sequence, quantity or importance, but are only used to distinguish different components. Words such as "comprises" or "comprising" and similar terms mean that the elements or items listed before "comprising" or "comprising" include the elements or items listed after "comprising" or "comprising" and their equivalents, and do not exclude other component or object. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

FIG. 1 is a schematic diagram of an imaging system 100 according to one embodiment. The imaging system 100 includes an X-ray source 11 , a detector array 13 and a correction module 15 . The X-ray source 11 is used to emit an X-ray beam 17 . The detector array 13 includes several detectors 131 . The detector 131 generates an initial signal in response to the X-ray beam 17 obliquely incident on the detector 131 . The initial signal comprises a parallax crosstalk signal in response to an X-ray beam 17 incident on an adjacent detector 131 . The correction module 15 is connected to the detector array 13 and used for generating a correction signal according to parallax crosstalk signals from adjacent detectors 131 .

The imaging system 100 includes an image acquisition unit 110 , a controller 120 , a processor 130 , an image reconstruction device 140 , a data storage device 150 , an input device 160 and a display device 170 . The image acquisition device 110 includes a gantry 20 , an X-ray source 11 , a detector array 13 , a carrying platform 22 and a receiving cavity 24 . The detector 131 includes at least one scintillator (not shown) and a photoreceptor (not shown). In some embodiments, the photoreceptors include photodiodes or phototransistors, but are not limited thereto. The X-ray source 11 and the detector array 13 are disposed opposite to the gantry 20 , and the two are separated by a housing cavity 24 . The detection object 26 is placed on the carrying platform 22 and can be located in the receiving cavity 24 together with the carrying platform 22 . In one embodiment, the X-ray source 11 and detector array 13 are arranged in rotation relative to the gantry 20 and the test object 26 . In another embodiment, the X-ray source 11 and detector array 13 remain stationary.

The X-ray source 11 emits an X-ray beam 17 towards the detector array 13 , the X-ray beam 17 passing through a test object 26 . When the X-ray beam 17 passes through the test object 26 , the test object 26 attenuates the X-ray beam 17 . The attenuated X-ray beam 17 is absorbed by the scintillator of the detector 131 . Scintillators convert absorbed X-rays into visible light. The photoreceptor converts visible light into an electrical signal, which is a signal representative of the intensity of the X-ray beam 17 in response to the initial signal of the X-ray beam 17 . The electrical signal generated by each photoreceptor is proportional to the intensity of the attenuated X-ray beam 17 received by the scintillator.

The controller 120 includes a stage control unit 30 , an X-ray control unit 32 , a gantry control unit 34 and a correction module 15 . The stage control unit 30 controls the movement of the stage 22 . The X-ray control unit 32 provides power and timing signals to the X-ray source 11 . The gantry control unit 34 controls the rotational speed and angular orientation of the X-ray source 11 . The correction module 15 receives the initial signal generated by the detector 131 and processes the initial signal to generate a projection signal and provide it to the image reconstruction device 140 . In one embodiment, the correction module 15 can be integrated with the stage control unit 30 , the X-ray control unit 32 and the gantry control unit 34 . In another embodiment, the correction module 15 can be integrated with the detector array 13 . The image reconstruction device 140 and the processor 130 reconstruct an image according to the projection signal. The reconstructed images are stored in the data storage device 150 . In an embodiment, the data storage device 150 also stores intermediate processing data when reconstructing images. The input device 160 is used for receiving input from a user. The display device 170 displays an image of the detection object 26 .

In some embodiments, the data storage device 150 may be a magnetic storage medium or an optical storage medium, such as a hard disk, a memory chip, etc., but is not limited thereto. In one embodiment, computer programs or instructions can be uploaded to the processor 130 through the input device 160 . The input device 160 may include buttons, audio input, video input, etc., but is not limited thereto. In some embodiments, the display device 170 may include a liquid crystal display, a cathode ray tube display, a plasma display, etc., but is not limited thereto.

Figure 2 shows a schematic diagram of an X-ray source 11 and detector array 13 of one embodiment. Detector array 13 includes one or more panel modules 133 . The flat panel module 133 is flat and includes a plurality of detectors 131 . The detectors 131 of each flat panel module 133 are arranged in the same plane. In this embodiment, the centers of the plurality of flat panel modules 133 are arranged on an arc 40 to form an approximate arc-shaped detector array 13 . The detector array 13 is composed of a plurality of separated flat panel modules 133, and the flat panel modules 133 are easier to process, and each flat panel module 133 contains relatively few detectors 131, so that its structure is small and the yield is high .

FIG. 3 shows a partial schematic view of the panel module 133 of one embodiment. The X-ray beam 17 obliquely enters the detector 131 of the flat panel module 133 through the detection object (not shown). The part of the X-ray beam 171 passing through the detection object only enters one detector 131 , and the part of the X-ray beam 173 passing through the detection object enters the edge of two adjacent detectors 131 . The initial signal generated by the detector 131 in response to the X-ray beam 17 includes a parallax crosstalk (Parallax Cross Talk) signal in response to an X-ray beam 173 incident to an adjacent detector 131 and a response to an X-ray beam incident to a detector 131. The true signal of beam 171. An X-ray beam 173 that strikes a first edge 135 of a detector 131 still strikes a second edge 137 of an adjacent detector 131 . Two adjacent detectors 131 respectively generate parallax crosstalk signals in response to the X-ray beams 173 directly incident on the first edge 135 and the second edge 137 after passing through the detection object, which can be referred to as a set of parallax crosstalk signals. An X-ray beam 171 is incident on the central portion 136 of the detector 131 and the detector 131 generates a true signal in response to the X-ray beam 171 . In one embodiment, the first and second edges 135 , 137 and the central part 136 are divided according to the incident direction of the X-ray beam 17 and the arrangement of the detector 131 by simulation software. After the detector 131 generates the initial signal, the parallax crosstalk signal and the real signal are separated by using simulation software. The correction module 15 shown in FIG. 1 is used to generate correction signals according to parallax crosstalk signals from adjacent detectors 131 . The correction module 15 corrects the parallax crosstalk signal corresponding to the first edge 135 and the parallax crosstalk signal corresponding to the second edge 137 to eliminate defects such as rings and black spots on the image caused by the parallax crosstalk signal. The correction module 15 processes the true signal generated by the detector 131 to generate a true projection signal.

In the embodiment shown in FIG. 3 , the detector array 13 includes several detection channels 139 along the incident direction of the X-ray beam 17 . In an embodiment, the projection signal generated according to the initial signal of at least one detection channel 139 includes a true projection signal. In one embodiment, the projection signal generated according to the initial signal of at least one detection channel 139 includes a true projection signal and a modified signal. In the embodiment shown in FIG. 3 , detection channel 139 includes a portion of adjacent detector 131 . The detection channel 139 includes a first edge 135 and a central portion 136 of one detector 131 and includes a second edge 137 of an adjacent detector 131 . The X-ray beam 17 entering the detection channel 139 includes the X-ray beam 171 entering one detector 131 and the X-ray beam 173 entering two adjacent detectors 131 . The correction module 15 processes the initial signal in response to the X-ray beam 17 entering the detection channel 139 to generate a projection signal. The initial signal of each detection channel 139 includes a set of parallax crosstalk signal and true signal. The correction module 15 generates a set of projection signals according to the initial signal of each detection channel 139 . In this embodiment, each group of projection signals includes a correction signal and a true projection signal. One set of parallax crosstalk signals is only in one detection channel 139 . The image reconstruction device 140 shown in FIG. 1 reconstructs an image according to the projection signal generated by the correction module 15 .

FIG. 4 is a partial schematic diagram of a panel module 133 according to another embodiment. The embodiment shown in FIG. 4 is similar to the embodiment shown in FIG. 3 . The main difference between the embodiment shown in FIG. 4 and the embodiment shown in FIG. 3 is that the detection channel 141 in the embodiment in FIG. The edge 135 and the second edge 137, the adjacent detection channels 142 only include the central portion 136 of one detector 131, and are arranged at intervals in this way. The initial signal of the detection channel 141 includes two sets of parallax crosstalk signals and a true signal, and the initial signal of the adjacent detection channel 142 only includes the true signal.

FIG. 5 is a partial schematic diagram of a panel module 133 according to another embodiment. The embodiment shown in FIG. 5 is similar to the embodiment shown in FIGS. 3 and 4 . Compared with the embodiments shown in FIGS. 3 and 4 , in the embodiment shown in FIG. 5 , the detection channel 143 includes a part of a detector 131 . The detection channel 143 comprises only the central part 136 of the detector 131, the initial signal of which detection channel 143 comprises only true signals. The adjacent detection channel 144 includes the first edge 135 of the detector 131 and the second edge 137 of the adjacent detector 131 , and the initial signal of the detection channel 144 only includes a set of parallax crosstalk signals. spaced like this. The correction signal and the true projection signal are generated according to the initial signals of different detection channels 143 , 144 respectively. Each group of parallax crosstalk signals is separated from the real signal, and is respectively processed to generate a modified signal and a true projection signal, and the modified signal and the true projection signal are used as different groups of projection signals. In this way, the parallax crosstalk signal is isolated and processed separately, and the sampling rate is indirectly increased, thereby improving the resolution of the image.

In an embodiment, the expression of the true projection signal prep'(n) is shown in expression (1):

prep'(n)=Log[I' _n (air)/I' _n (λ)]

=Log[I _n (air)/I _n (λ)]+Log[I' _n (air)*I _n (λ)/(I _n (air)*I' _n (λ))] (1)

=prep(n)+f'(prep(n))

Wherein, I' _n (air) represents the true signal that detector 131 produces when X-ray passes through air and directly injects detector 131; I' _n (λ) represents X-ray and injects detector 131 after passing through detection object The real signal produced by the detector 131; In (air) represents the initial signal produced by the detector 131 when the X _- ray passes through the air and directly shoots into the detector 131; In (λ) represents that the X _- ray passes through the detection object The initial signal that detector 131 produces when incident detector 131; n represents the nth detector 131; λ represents the thickness of detection object; prep (n) represents the initial projection signal that obtains according to the initial signal that detector 131 produces, prep (n)=Log[I _n (air)/I _n (λ)]; f'(prep(n)) is the correction function of true projection signal, f'(prep(n))=Log[I' _n ( air)*I _n (λ)/(I _n (air)*I' _n (λ)), I' _n (air) and I _n (air) are constants, so the correction function changes with the thickness λ of the detection object And change.

Similar to the true projection signal prep'(n), the expression of the modified signal prep"(n) is shown in expression (2):

prep"(n)=Log[I" _n (air)/I" _n (λ)]

=Log[I _n (air)/I _n (λ)]+Log[I" _n (air)*I _n (λ)/(I _n (air)*I" _n (λ))] (2)

=prep(n)+f"(prep(n))

Wherein, I " _n (air) represents the parallax crosstalk signal that detector 131 produces when X-ray passes through air and directly injects detector 131; I " _n (λ) represents that X-ray enters detector after passing through detection object The parallax signal that detector 131 produces at 131; f " (prep (n)) is the modification function of correction signal, f " (prep (n))=Log[I" _n (air)*I _n (λ)/( I _n (air)*I" _n (λ)), I" _n (air) is a constant, and the correction function changes with the thickness λ of the detection object.

The true projection signal prep'(n) and the corrected signal prep"(n) are respectively corrected and obtained on the basis of the initial projection signal prep(n), and the correction functions are related to the thickness λ of the detection object. In one embodiment, Obtain the value of the correction function corresponding to the different thicknesses of the detection object by experimental simulation, and can quickly obtain the value of the corresponding correction function by looking up the table in actual detection.In the simulation experiment, the detection object can be simulated by water film, but not limited to water film. According to the actual application, the above real projection signal prep'(n) and the correction signal prep"(n) can be further processed, and the correction functions of the two can be adjusted respectively to adapt to the actual application, so as to obtain a more accurate projection signal , so that a clearer and more accurate image can be obtained.

Although the present invention has been described in conjunction with specific embodiments, those skilled in the art will appreciate that many modifications and variations can be made to the present invention. It is, therefore, to be realized that the intent of the appended claims is to cover all such modifications and variations as are within the true spirit and scope of the invention.

Claims (9)

1. a kind of imaging system, it is characterised in that it includes：

X-ray source, for launching X-ray beam；

Detector array, including some detectors, the detector are penetrated for producing the oblique X- for being incident upon the detector of response The initial signal of wire harness, the initial signal include the parallax crosstalk letter that response is incident to the X-ray beam of the adjacent detector Number；And

Correcting module, the detector array is connected to, and is produced for correcting the parallax crosstalk signal from adjacent detector Revise signal,

The detector array includes one or more flat sheet moulds, and the flat sheet mould includes the detector, each described The detector arrangement of flat sheet mould in the same plane, wherein according to the incident direction of X-ray beam and the detector Arrangement separation parallax crosstalk signal and true signal.

2. imaging system as claimed in claim 1, it is characterised in that：The center of multiple flat sheet moulds is arranged in an arc In shape.

3. a kind of imaging system, it is characterised in that it includes：

X-ray source, for launching X-ray beam；

Detector array, including some detectors, the detector are penetrated for producing the oblique X- for being incident upon the detector of response The initial signal of wire harness, the initial signal include the parallax crosstalk letter that response is incident to the X-ray beam of the adjacent detector Number；And

Correcting module, the detector array is connected to, and is produced for correcting the parallax crosstalk signal from adjacent detector Revise signal,

The initial signal includes the true signal that response is incident to the X-ray beam of a detector, the detector array Include the sense channel of some incident directions along the X-ray beam, the correcting module is used for injecting the inspection according to response Initial signal caused by the X-ray beam surveyed in passage produces projection signal and produces true projection signal according to the true signal.

4. imaging system as claimed in claim 3, it is characterised in that：According to the described initial of at least one sense channel The projection signal caused by signal includes the true projection signal.

5. the imaging system as described in claim 3 or 4, it is characterised in that：According to the initial of at least one sense channel The projection signal caused by signal includes the true projection signal and the revise signal.

6. imaging system as claimed in claim 3, it is characterised in that：Produced according to the initial signal of a sense channel The projection signal include the true projection signal and the revise signal, and according to the initial of the adjacent sense channel The projection signal caused by signal includes the true projection signal.

7. imaging system as claimed in claim 3, it is characterised in that：The revise signal and true projection signal's difference root Produced according to the initial signal of the different sense channels.

8. imaging system as claimed in claim 3, it is characterised in that：The sense channel includes the one of a detector Part.

9. imaging system as claimed in claim 3, it is characterised in that：The sense channel includes the one of the adjacent detector Part.