CN216907989U - CT device - Google Patents

Abstract

The utility model relates to a CT device, belongs to the technical field of X-ray computed tomography imaging, and solves the problem that in the prior art, when the number of rows of detectors is too large, the cone angle of a ray source is difficult to cover the detectors or cone angle artifacts are caused by too large cone angle. A CT apparatus includes a rotating body, a detector and a radiation source; the detector and the ray source are both fixed on the rotating body; the detectors are sequentially arranged along the direction of the rotating shaft of the rotating body to form a detector row; the radiation source comprises a plurality of radiation source focuses arranged along the direction of the rotation axis of the rotating body, and each radiation source focus radiates a partial region of the detector row. The utility model realizes the purpose of effectively inhibiting cone angle artifacts of reconstructed images when a large-width multi-row detector is used.

Description

CT device

Technical Field

The utility model relates to the technical field of X-ray computed tomography imaging, in particular to a CT device.

Background

Among X-ray-based explosive inspection technologies, X-ray computed tomography imaging (CT) technology has been highly regarded in the field of security inspection because of its own unique advantages. An eds (application Detection system) type Security inspection device uniquely certified by the Transportation Security Administration (TSA) is a CT device, and the position of the X-ray CT technology in the Security inspection field can be seen.

The current CT apparatus is mainly a spiral CT based on a slip ring technology, and the radiation source and the detector are usually arranged on a rotating gantry, and the problem of continuous rotation of the gantry is solved by the slip ring technology. To increase the scan field of view for a single gantry rotation, a larger scan area is covered, typically by increasing the number of detector rows. As the number of rows of medical CT detectors in the current market is up to 320, the coverage of the Z direction is about 16 cm. However, as the ray sources used by the device are mostly point sources, the included angle between the edge detector and the ray source is increased along with the increase of the number of rows, so that the reconstructed image has more and more serious cone angle artifacts.

SUMMERY OF THE UTILITY MODEL

Based on the above analysis, the present invention aims to provide a CT apparatus, which solves the problem in the prior art that when the number of rows of detectors is too large, the cone angle of the radiation source is difficult to cover the detectors, or the cone angle is too large, which causes cone angle artifacts.

The purpose of the utility model is mainly realized by the following technical scheme:

the utility model provides a CT device, which comprises a rotating main body, a detector and a ray source, wherein the rotating main body is provided with a first end and a second end; the detector and the ray source are both fixed on the rotating body; the detectors are sequentially arranged along the direction of the rotating shaft of the rotating body to form a detector row; the radiation source comprises a plurality of radiation source focuses arranged along the direction of the rotation axis of the rotating body, and each radiation source focus radiates a partial region of the detector row.

Optionally, a partial region of the detector row forms an angle with the source focus at the source focus, the angle being no greater than 15 °.

Optionally, there is an overlap of regions of the detector rows adjacent to the radiation source focal spot radiation.

Optionally, a radiation confining element is arranged at a focal spot of the radiation source.

Optionally, the radiation limiting member is disposed at the beam outlet of the radiation source.

Optionally, the radiation limiter is made of a heavy metal material.

Optionally, the heavy metal material comprises lead and tungsten.

Optionally, the source of radiation comprises a hot cathode X-ray tube based on a gated technique.

Optionally, the detector is a monoenergetic detector.

Optionally, the detector is a photon counting detector.

Optionally, the source focal spot is turned on at different times.

Optionally, the object conveying means comprises a motion motor and a conveyor belt.

Optionally, the object transport component comprises a motion motor and a CT scanning bed.

Optionally, the radiation source comprises a carbon nanotube based cold cathode X-ray tube.

Optionally, a scattering confinement is provided at the detector.

Optionally, the scattering limiter is disposed in front of the detector, aligned with a source focus.

Optionally, the radiation shielding device is a lead curtain.

The utility model can realize at least one of the following beneficial effects:

(1) the medical CT detector is generally a multi-row detector, the row number of the existing medical CT detector is up to 320, the Z direction covers about 16cm, and as the ray sources used by the equipment are mostly point sources, the included angle between the edge detector and the ray source is increased along with the increase of the row number, so that the reconstructed image has more and more serious cone angle artifacts. The utility model breaks through the inherent cognition that a ray source of the spiral CT can only be a point source ray source, creatively adopts a multi-focus ray source as the ray source of the spiral CT, and limits a power ray source to a region radiated by a focus point of each ray source, so that each ray source focus does not radiate all detectors on the whole detector row, but only radiates detectors in partial regions, namely, partial regions of the detector row and the ray source focus form a certain angle (not more than 15 degrees) at the focus point of the ray source, thereby preventing the reconstructed image from generating cone angle artifacts when a plurality of rows of detectors (more than the existing 320 rows of detectors) are used, and further ensuring the reconstructed clear image.

(2) The radiation limiting part is arranged at the focus of each ray source, or the scattering limiting part is arranged at the detector, so that the radiation area of the focus of each ray source is limited, and the realization of the radiation part area of the focus of each ray source is ensured.

(3) The utility model can meet the integrity requirement of scanned object data by controlling the overlapping of the areas of the detector rows radiated by the adjacent ray sources.

(4) The method can ensure that when the number of rows of the detectors is more than 320 and the coverage in the Z direction exceeds 16cm, the reconstructed image is clear and cone angle artifacts do not appear.

(5) According to the imaging method, the CT ray sources open and close the focuses according to a set sequence (for example, adjacent ray sources are opened and closed in sequence and are turned back), only one ray source focus is opened in a single time or a plurality of ray source focuses are opened at the same time by quickly switching the ray source focuses, but the ray emission ranges corresponding to the two ray source focuses received by the detector are not intersected, so that the problem of cone angle artifacts caused by the fact that rays of the ray source focuses irradiate the same detector at the same time is avoided, and a clear image is guaranteed to be reconstructed.

In the utility model, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the utility model will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model. The objectives and other advantages of the utility model will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the utility model, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a schematic diagram of a relationship between positions of a multi-focal spot source and a plurality of rows of detectors according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a distribution range of a plurality of radiation sources and corresponding detector region structures according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a capacitively coupled slip ring according to an embodiment of the present invention;

FIG. 4 is a partial cross-sectional view of a rotating disk according to an embodiment of the present invention;

FIG. 5 is a graph of spacing between adjacent transmit antennas versus antenna width for the prior art;

fig. 6 is a partial cross-sectional view of a turntable with a built-in transmitting antenna according to an embodiment of the present invention.

Reference numerals:

1-a detector; 2-multiple focal spot source; 3-ray source focus; 4-direction of rotation axis; 7-detector row; 8-rotating the disc; 9-a transmission antenna; 10-a first groove; 11-a second groove; 12-a receiving unit.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the utility model and together with the description, serve to explain the principles of the utility model and not to limit the scope of the utility model.

Example one

Referring to fig. 1, an embodiment of the present invention discloses a CT system, comprising: an object conveying component, an object inlet and an object outlet and a CT device. The CT apparatus includes a rotating body, a detector 1, and a radiation source. The detector 1 and the radiation source are both fixed on the rotating body. The detectors 1 are arranged in a plurality of rows, and the detectors in the plurality of rows are sequentially arranged along the rotating axis direction 4 of the rotating body to form a detector row 7.

The radiation source is a multi-focal spot radiation source 2 comprising a plurality of radiation source focal spots 3 arranged along a direction of a rotational axis 4 of the rotating body. Preferably, the radiation source can be a cold cathode X-ray tube based on carbon nano-tubes, and can also be a hot cathode X-ray tube based on grid control technology.

The detector 1 of the present embodiment may be any one or combination of multiple single-energy detectors, dual-energy detectors, and photon counting detectors, and may also be a flat panel detector or a multi-row detector.

In particular systems, in addition to the multiple focal spot source 2, additional multiple focal spot sources may be arranged at other positions of the rotating body. Furthermore, the arrangement of the focal spots in the multi-focal spot source 2 may be an area array, for example, the focal spots are arranged in a 3 x 2 manner in a plane parallel to the direction of the rotational axis of the rotating body.

It should be noted that, if not limited, each source focal point 3 corresponds to the whole detector row 7, which results in an increased angle between the edge detector and the source, and thus a very serious cone angle artifact occurs in the reconstructed image.

The method aims to solve the technical problem that due to the fact that the included angle between an edge detector and a ray source is increased, a reconstructed image has serious cone angle artifacts. Referring to fig. 2, in a possible embodiment, the radiation area of each source focal spot is limited, instead of corresponding to the whole detector row 7, each source focal spot corresponds to a partial area of the detector, i.e. each source focal spot 3 corresponds to a unit at a different position on the detector row 7. Specifically, each radiation source focus can only radiate a detector within a certain angle range, as shown in fig. 2, a partial region of the detector row and the radiation source focus form a certain angle at the radiation source focus, and the angles of the detectors radiated by the three radiation source focuses are α, β, and θ, respectively.

In particular, the detector row 7 in fig. 2 is located in the same two-dimensional plane parallel to the direction of the axis of rotation 4 of the rotating body as the plurality of source foci 3. The cone angles α, β and θ assumed by each source focal spot 3 in the figure preferably range no more than 15 °. The detector units within the cone angle range are the detectors corresponding to the radiation source focal points, for example, in fig. 2, the detector unit corresponding to the first radiation source focal point 3 is the portion where the cone angle α corresponds to the upper and lower edges of the detector. Due to the integrity requirement of the scanned object data, the detector regions corresponding to adjacent source focal spots 3 overlap.

In order to achieve a limitation of the radiation range of the radiation source focus, in one possible embodiment a radiation limitation element is provided at each radiation source focus, or a scattering limitation element is provided at the detector.

The radiation limiting part is arranged at the beam outlet of the radiation source and is made of heavy metal materials such as lead, tungsten and the like and used for limiting the ray beam to a narrow range so as to control the solid angle of the ray beam.

The specific structure of the radiation limiting member can take various forms as long as the solid angle of the beam can be controlled, and the purpose of limiting the ray bundle to a narrow range can be achieved.

The scattering confinement is placed in front of the detector and shaped like a set of grids arranged in alignment with the source focus, thereby blocking stray primary X-photons from entering the detector.

In order to increase the operation safety, the embodiment is further provided with a ray shielding device at the object entrance and exit. Illustratively, the radiation shield may be a lead curtain.

The CT system of the embodiment can be applied to the field of security inspection and also can be applied to the field of medical treatment. When applied to the field of security inspection, the object conveying components are generally a moving motor and a conveying belt; when applied to the medical field, the object transport components are typically a motion motor and a CT scanning table.

Example two

In another embodiment of the utility model, a multi-row detector imaging method based on a multi-focal-point ray source is disclosed, which can reconstruct an image without cone angle artifacts when a multi-row detector is used. The imaging method is completed by adopting the CT system of the first embodiment, and comprises the following steps:

step 1: placing objects (luggage) on a conveyor belt, and keeping the objects (luggage) to travel at a constant speed along with the conveyor belt under the drive of a conveyor belt motor;

step 2: an object (luggage) enters a CT scanning area, a slip ring motor controls a CT slip ring to rotate at a constant speed, a CT ray source opens and closes focuses according to a set sequence (for example, adjacent ray sources are opened and closed in sequence and are turned back), only one focus is opened in a single time by quickly switching the focuses of the ray sources, and the problem of cone angle artifacts caused when rays of a plurality of focuses irradiate the same detector at the same time is solved; or a plurality of radiation source focuses are opened at the same time, but the ray emission ranges corresponding to the two radiation source focuses received by the detector do not have an intersection;

and step 3: the ray source emits X ray beam to penetrate the object, the CT detector receives the attenuation signal penetrating the object and transmits the received signal into the data processing computer;

and 4, step 4: and reconstructing data in a data processing computer, acquiring fault data of different positions of the object, and then displaying three-dimensional data formed by all faults on a screen in a three-dimensional mode.

The imaging method of the embodiment opens the focuses according to the set sequence, so that only one focus is opened at a single moment, and the scanning is completed by quickly switching the focuses, thereby avoiding the situation that rays of a plurality of focuses irradiate the same detector at the same time; or a plurality of ray source focuses are simultaneously opened, but ray emission ranges corresponding to the two ray source focuses received by the detector do not intersect, so that cone angle artifacts are avoided, and a clear image is guaranteed to be reconstructed.

For the implementation of fast switching of the focus, it can be realized by controlling hardware. For example, a gate switch is set to control the exposure time and the line sequence of the tube.

EXAMPLE III

In another embodiment of the present invention, the CT rotating body of the first embodiment is a capacitively coupled slip ring using slip ring technology. Comprising a rotating disc 8, a transmitting unit and a receiving unit.

As shown in fig. 3, the sending unit includes a sending antenna 9 and a sending end data processing unit, the sending end data processing unit includes a sending circuit board and a data line, and both the sending antenna 9 and the data line are connected to the sending circuit board. The transmitting antenna 9 is connected to the transmitting circuit board, illustratively in the form of a connector. The transmitting circuit board is fixed on the rotating disc.

The shape of the transmitting antenna adopted by the utility model is flat, or strip.

The rotating disc is in a large-aperture ring shape with a hollow interior, a first groove 10 is circumferentially arranged on the outer surface of the rotating disc, the shape of the first groove 10 is matched with that of the transmitting antenna 9, and the transmitting antenna 9 is arranged in the first groove 10.

It should be noted that, depending on the diameter of the rotating disk, the number of the transmitting antennas located in the first groove 10 may be 1, or a plurality of transmitting antennas may form a complete circle. Specifically, the circuit board has two vias, and the adjacent antennas are connected to one via of the circuit board, respectively. The receiving unit comprises a receiving circuit board and a data line, and the data line is connected with the receiving circuit board.

The receiving unit 12 includes two parts, namely a receiving end data processing unit and a receiving antenna, which can be integrated on a printed circuit or connected in a plug-in manner.

The receiving unit comprises a first receiving unit and a second receiving unit, wherein the first receiving unit is arranged near the outer surface of the rotating disc and is 1.5-5mm away from the transmitting antenna in the first groove.

In a possible embodiment, the inner surface of the rotating disc 8 is also provided with a circumferentially arranged groove (second groove 11), as shown in fig. 4. The shape of the second recess 11 matches the shape of the transmitting antenna, which is placed in the second recess.

It should be noted that the transmitting antenna 9 in the present embodiment is fixed in the groove, and for example, the transmitting antenna may be fixed in the groove by means of adhesion.

The second receiving unit is arranged near the inner surface of the rotating disc and is 1.5-5mm away from the transmitting antenna in the second groove.

It should be noted that the number of the first grooves 10 and the second grooves 11 is at least one. For example, 1 first groove, 1 second groove; or 1 first groove and 2 second grooves; 2 first grooves and 1 second groove; alternatively, 2 first grooves, 2 second grooves, as shown in fig. 4. The position of the second groove may or may not correspond to the position of the first groove.

The transmission unit and the receiving unit are realized by a capacitive coupling principle, namely, electric field coupling between the transceiving antennas. If the distance between the different groups of transceiving antennas is too close, crosstalk between different transceiving modules occurs, which causes abnormal communication. Therefore, in order to prevent signal interference between the different transmitting antennas on the same side, the spacing D between the different transmitting antennas on the same side in the related art is not less than three times the width W of the transmitting antenna (i.e., 3W), and the dielectric thickness H between the different transmitting antennas on different sides is not less than three times the width of the transmitting antenna, as shown in fig. 5 (for convenience of expression, the transmitting antennas are illustrated as protruding the outer surface of the rotating disk).

However, due to space constraints, it is not possible to increase the distance between different transceiver modules indefinitely. Therefore, in one possible embodiment of the utility model, a solution with an embedded receiving antenna is used, i.e. the depth of the recess is not the same as the thickness of the transmitting antenna, but the depth of the recess is larger than the thickness of the transmitting antenna, as shown in fig. 6. Thus, after the transmitting antenna is placed in the groove, the upper surface of the transmitting antenna has a height difference from the outer surface of the rotating disk, i.e., the upper surface of the transmitting antenna is not flush with the outer surface of the rotating disk, but is lower than the outer surface of the rotating disk.

Specifically, the thickness of the antenna is 2mm, and the depth of the groove is 3 mm. So that the surface of the transmitting antenna is at a distance of 1mm from the side of the rotating disc. Above-mentioned setting can effectively reduce the radiation field of sending signal, consequently, even reduce under the condition of the interval between the different groups of transmitting antenna, also can reduce the interference between the different receiving and dispatching module groups, under the circumstances of guaranteeing signal normal communication, effectively improves the utilization ratio of electrical slip ring disk body.

Through experimental research, the utility model discovers that by adopting the embedded structure, the distance between the sending antennas at the same side does not need to reach 3 times (namely 3W) of the width of the sending antenna, and the normal communication can be ensured only by 1-2 times of the width of the sending antenna.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims (10)

1. A CT apparatus comprising a rotating body, a detector and a radiation source; the detector and the ray source are both fixed on the rotating body;

the detectors are sequentially arranged along the direction of the rotating shaft of the rotating body to form a detector row;

the radiation source comprises a plurality of radiation source focuses arranged along the direction of the rotation axis of the rotating body, and each radiation source focus radiates a partial region of the detector row.

2. The CT apparatus of claim 1, wherein the partial region of the detector row forms an angle with the source focal spot at the source focal spot, the angle being no greater than 15 °.

3. The CT apparatus of claim 1, wherein regions of the detector rows adjacent to the radiation source focal spot radiation overlap.

4. A CT arrangement according to any of the claims 1-3, wherein a radiation limiting member is arranged at the focus of the radiation source.

5. The CT apparatus of claim 4, wherein the radiation limiting member is disposed at the source exit.

6. The CT apparatus of claim 1, wherein a scattering limiter is disposed at the detector.

7. The CT apparatus of claim 1, wherein the radiation source comprises a carbon nanotube-based cold cathode X-ray tube.

8. The CT apparatus of claim 1, wherein the source of radiation comprises a hot cathode X-ray tube based on a gated technique.

9. The CT apparatus of claim 1, wherein the detector is a monoenergetic detector.

10. The CT apparatus of claim 1, wherein the detector is a photon counting detector.

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