CN108169787B

CN108169787B - PET detector, PET system and PET detection method

Info

Publication number: CN108169787B
Application number: CN201711449717.4A
Authority: CN
Inventors: 蒋华伟; 刘伟平
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2017-12-27
Filing date: 2017-12-27
Publication date: 2020-10-13
Anticipated expiration: 2037-12-27
Also published as: CN108169787A

Abstract

The invention discloses a PET detector, a PET system and a PET detection method, and relates to the technical field of medical instruments. The PET detector comprises a PET ring, a PET detection mechanism, a shielding mechanism and an adjusting mechanism, wherein the PET detection mechanism is arranged on the inner surface of the PET ring and comprises a crystal array; the shielding mechanism covers the surface of the crystal array, which is far away from the PET ring, a grid is arranged on the shielding mechanism, and the size of a gap of the grid is smaller than that of a single crystal unit in the crystal array; the adjusting mechanism is fixed on the end face of the PET ring and connected with the shielding mechanism, and the adjusting mechanism can drive the shielding mechanism to move so as to adjust the shielding position of the shielding mechanism on the surface of the crystal array. The invention has simple structure and convenient operation, effectively improves the resolution of the PET detector, improves the image quality and reduces the production cost on the premise of not changing the crystal size.

Description

PET detector, PET system and PET detection method

Technical Field

The invention relates to the technical field of medical instruments, in particular to a PET detector, a PET system and a PET detection method.

Background

Positron Emission Tomography (PET) detectors are commonly provided in various large medical devices that employ PET technology, such as: the PET Imaging device is currently the most advanced medical diagnostic device provided in a Positron Emission Tomography-Computed Tomography (PET-CT) apparatus or a PET-MRI (PET-MRI) apparatus.

The working principle of the PET detector is as follows: injecting into a living body an isotope-labeled drug (imaging agent) having a positron emission function, which undergoes annihilation effect in a process involved in physiological metabolism of the living body to generate two gamma-ray photons emitted substantially in a 180 ° direction and having an energy of 0.511MeV and moving in opposite directions to each other; according to different capacities of different parts of an organism for absorbing the labeled compound, the concentration degree of isotopes at each part in the organism is different, and the intensity of photons generated by annihilation reaction is different; therefore, the time, the position, the quantity and the direction of photons released by the organism can be detected by the PET detector surrounding the organism, the optical signal is converted into a time pulse signal by the photomultiplier, and the information is acquired, stored, operated, subjected to digital/analog conversion and image reconstruction by a computer system, so that an image of a corresponding organ of the organism is obtained. The tissues or lesions with high metabolic rate present bright high metabolic bright signals on the PET image, and the tissues or lesions with low metabolic rate present low metabolic dark signals on the PET image.

The current PET detectors are moving towards high resolution, high sensitivity, low dose, and the resolution of the PET detectors is limited in hardware primarily by the size of the crystal size within the detector. Generally, the smaller the crystal size, the higher the resolution of the PET detector. However, under current technical conditions, it is difficult to further reduce the size of the crystals within a reasonable cost.

Disclosure of Invention

Based on the above, the present invention provides a PET detector, a PET system, and a PET detection method, in which a shielding mechanism is added to the PET detector, so that the resolution of the PET detector can be effectively improved without changing the crystal size.

In order to achieve the purpose, the invention adopts the following technical scheme:

a PET detector, comprising:

a PET ring;

the PET detection mechanism is arranged on the inner surface of the PET ring and comprises a crystal array;

the shielding mechanism covers the surface of the crystal array, which is far away from the PET ring, a grating is arranged on the shielding mechanism, and the gap size of the grating is smaller than the size of a single crystal unit in the crystal array; and

the adjusting mechanism is fixed on the PET ring and connected with the shielding mechanism, and the adjusting mechanism can drive the shielding mechanism to move so as to adjust the shielding position of the shielding mechanism on the surface of the crystal array.

Preferably, the shielding mechanism comprises a support ring and a plurality of shielding strips arranged in the support ring, the support ring is connected with the adjusting mechanism, the support ring is parallel or coaxial with the axis direction of the PET ring, and the plurality of shielding strips form the grating.

Preferably, the shielding strip extends along the circumferential direction of the support ring, the adjusting mechanism is one of an air cylinder, a hydraulic cylinder or a linear motor, and the adjusting mechanism can drive the shielding mechanism to move along the axial direction of the support ring.

Preferably, the shielding strip extends along the axis direction of the support ring, the adjusting mechanism comprises a motor and a transmission assembly, and the adjusting mechanism can drive the shielding mechanism to rotate along the circumferential direction of the support ring.

Preferably, a part of the shielding strips in the plurality of shielding strips extend along the circumferential direction of the support ring, and the other part of the shielding strips extend along the axial direction of the support ring to form a grid-shaped structure; the adjusting mechanism can drive the shielding mechanism to axially move along the support ring and rotate along the circumferential direction of the support ring.

Preferably, a plurality of said screen strips are evenly distributed on said support ring.

Preferably, the material of the shielding mechanism is one or more of iron, steel, lead, tungsten or copper.

Preferably, the width of the gap is 1/10-9/10 of the width of a single crystal unit.

A PET system comprises a detector control unit and further comprises the PET detector in any one of the above schemes, and the PET detector is connected with the detector control unit.

A PET detection method using the PET detector, the detection method comprising the steps of:

s1: adjusting the initial position of a shielding mechanism, shielding part of the surface of the crystal array, and carrying out primary detection on a target detection object to obtain a first PET image;

s2: changing the position of the shielding mechanism, shielding the surface of the rest part of the crystal array, and detecting the target detection object again to obtain a second PET image;

s3: and fusing the first PET image and the second PET image to obtain an integral PET image of the target detection object.

s1: adjusting the initial position of a shielding mechanism, shielding the first part surface of the crystal array, and carrying out primary detection on a target detection object to obtain a first PET image;

s2: changing the position of the shielding mechanism along the axial direction of the PET ring, shielding the second part surface of the crystal array, and detecting the target detection object again to obtain a second PET image;

s3: changing the position of the shielding mechanism along the circumferential direction of the PET ring, shielding the third part of the surface of the crystal array, and detecting the target detection object again to obtain a third PET image;

s4: changing the position of the shielding mechanism along the axial direction of the PET ring, shielding the surface of the rest part of the crystal array, and detecting the target detection object again to obtain a fourth PET image;

s5: and fusing the first PET image, the second PET image, the third PET image and the fourth PET image to obtain an integral PET image of the target detection object.

The invention has the beneficial effects that:

according to the invention, the shielding mechanism is arranged in the PET detector, the grating is arranged in the shielding mechanism, and as the size of the gap in the grating is smaller than that of a single crystal unit in the detector, rays can only enter the detector crystal through the gap during imaging and generate corresponding signal data, and then, when image reconstruction is carried out, an interval exists in the middle of an image obtained by using the part of signal data, so that compared with a detector without the shielding mechanism, the resolution of the image is effectively improved. Then, the adjusting mechanism drives the shielding mechanism to move along the axial direction of the support ring and/or rotate along the circumferential direction of the support ring, the crystal which is not shielded by the shielding mechanism originally is shielded, at the moment, the shielded crystal starts to receive rays and generate corresponding signal data, then image reconstruction is carried out, an image which is complementary with the previous image is generated, and the resolution of the image is effectively improved. And finally, carrying out fusion processing on the images obtained before and after the fusion processing to obtain the final integral image with high resolution. The invention has simple structure and convenient operation, greatly improves the resolution of the PET detector, improves the image quality and reduces the production cost on the premise of not changing the crystal size.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

FIG. 1 is a schematic diagram of a PET detector according to an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a detection module according to an embodiment of the present invention;

FIG. 3 is a schematic view of a shielding mechanism according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a PET detector provided in a second embodiment of the invention;

fig. 5 is a schematic structural diagram of a detection module according to a second embodiment of the present invention;

fig. 6 is a schematic structural view of a shielding mechanism according to a second embodiment of the present invention.

In the figure:

1-a PET ring; 2-a PET detection mechanism; 21-a crystal array; 22-an array of photomultiplier tubes; 3-a shielding mechanism; 31-a support ring; 32-a masking strip; 4-an adjustment mechanism; and 5, a frame.

Detailed Description

In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

As shown in FIG. 1, the present embodiment provides a PET detector, which can be used in a PET-CT apparatus or a PET-MRI apparatus for medical examination of an organism. This PET detector includes PET ring 1, PET detection mechanism 2, shelters from mechanism 3, adjustment mechanism 4 and frame 5, and wherein PET ring 1 is fixed in on the frame 5, and PET ring 1's shape is ring shape, and its inboard fixed mounting has PET detection mechanism 2 who is ring circular structure together for form the support to PET detection mechanism 2. Specifically, as shown in fig. 2, the PET detection mechanism 2 includes a crystal array 21 located at an inner circle and a photomultiplier array 22 located at an outer circle, wherein the crystal array 21 is used for receiving gamma rays emitted from a living body, and the photomultiplier array 22 is closely attached to an outer side of the crystal array 21 and is used for converting an optical signal received by the crystal array 21 into a pulse signal. Here, the crystal array 21 includes a plurality of crystal units, which are arranged in an array in the circumferential direction and the axial direction in the inner ring of the PET detection mechanism 2; similarly, the photomultiplier array 22 includes a plurality of photomultiplier units arranged in an array in the circumferential direction and the axial direction in the outer ring of the PET detection mechanism 2, and specifically, the photomultiplier units may be silicon photomultipliers, each of which corresponds to at least one crystal unit. Preferably, in this embodiment, the PET detection mechanism 2 is divided into a plurality of detector modules along the circumferential direction, wherein each detector module (as shown in fig. 2) includes a photomultiplier unit, the photomultiplier unit is correspondingly provided with 60 crystal units, and the 60 crystal units are arranged in an array of 5 × 12 along the circumferential direction and the axial direction of the PET detection mechanism 2, so that the arrangement not only simplifies the structure of the detector and facilitates the processing and installation, but also the signals received by the same detection module can be read out by the same integrated chip, thereby reducing the number of the signals and improving the working efficiency of the detector. Of course, the above is only an example, in other cases, each detector module may include a plurality of photomultiplier tube units, each photomultiplier tube unit may correspond to one or more crystal units, and the specific number and arrangement thereof may be flexibly adjusted according to actual situations.

Further, the shape of each crystal unit can be a cuboid, a cube or a cylinder, and the crystal units are specifically arranged according to the actual requirements of different PET detectors. In this embodiment, the crystal units are preferably in a cubic structure, so that a plurality of crystal units can be more conveniently arranged in a rectangular array, and the manufacturing process of the PET detection mechanism 2 is simplified. The material of the crystal unit can be at least one of aluminum gadolinium gallate, bismuth germanate, lutetium silicate, yttrium lutetium silicate, gadolinium silicate, yttrium silicate, barium fluoride, sodium iodide, cesium iodide, lead tungstate, yttrium aluminate, lanthanum bromide, lanthanum chloride, calcium titanium lutetium aluminum, lutetium pyrosilicate, lutetium aluminate and lutetium iodide, so that the optical performance of the crystal unit and the coupling performance with the photomultiplier unit can be ensured.

Further, as shown in fig. 3, the shielding mechanism 3 is also a circular ring structure and is sleeved in the crystal array 21, so as to cover the surface of the crystal array 21 away from the PET ring 1. The shielding mechanism 3 comprises two support rings 31 positioned at two ends and a plurality of shielding strips 32 arranged between the two support rings 31, wherein the support rings 31 are parallel or coaxial with the axis direction of the PET ring 1, and the support rings 31 are connected with the adjusting mechanism 4 and are used for supporting the shielding mechanism 3; the shielding strips 32 are respectively arranged in an array form along the circumferential direction and the axial direction in the circular ring of the shielding mechanism 3. Specifically, in the present embodiment, the length direction of each shielding strip 32 is consistent with the circumferential direction of the support ring 31, that is, each shielding strip 32 extends along the circumferential direction of the support ring 31; and a plurality of shielding strips 32 are uniformly arranged at intervals in the axial direction of the support ring 31 to ensure the uniformity of shielding the gamma rays by the shielding mechanism 3, thereby obtaining a PET image with higher quality. The plurality of shielding bars 32 form a grid structure, and two axially adjacent shielding bars 32 have a gap therebetween, and the width of the gap is smaller than the width of a single crystal unit in the crystal array 21. Preferably, the shielding mechanism 3 may be made of one or more of iron, steel, lead, tungsten, or copper, and the materials can ensure that the shielding mechanism 3 has a good shielding effect on gamma rays, so as to avoid affecting the imaging of the PET detector. In the embodiment, the shielding mechanism 3 is arranged in the PET detector, the grating structure is arranged in the shielding mechanism 3, and because the width of the gap in the grating structure is smaller than the width of a single crystal unit in the detector, when imaging is performed, gamma rays can only enter the crystal array 21 through the gap and generate corresponding signal data, and then when image reconstruction is performed, an interval exists in the middle of an image obtained by using the part of signal data, so that compared with a PET detector without the shielding mechanism, the embodiment effectively improves the resolution of the image. It should be noted that the number of times of movement of the shielding mechanism 3 is not limited to one time during the whole detection process, and therefore, in order to make all surfaces of the crystal array 21 receive the gamma rays, the sum of the distances of the respective movements of the shielding mechanism 3 should be ensured to be greater than or equal to the width of each shielding strip 32.

Further, the adjusting mechanism 4 is fixed on the PET ring 1, and the output end of the adjusting mechanism is fixedly connected with the shielding mechanism 3. In this embodiment, the adjusting mechanism 4 may be one of structures such as an air cylinder, a hydraulic cylinder, and a linear motor, and the adjusting mechanism 4 drives the shielding mechanism 3 to move along the axial direction of the support ring 31. Specifically, the amount of movement of the shutter mechanism 3 should be kept consistent with the width of the gap. According to the invention, the adjusting mechanism 4 drives the shielding mechanism 3 to move, so that the crystal which is not shielded by the shielding mechanism 3 is shielded, the original shielded crystal starts to receive gamma rays and generate corresponding signal data, then image reconstruction is carried out, an image complementary with the previous image is generated, and the resolution of the image is effectively improved. And finally, carrying out fusion processing on the images obtained in the two times to obtain the final integral image with high resolution.

Further, the width of the gap is preferably equal to the width of the shielding strip 32, and the width of the gap can be 1/10-9/10 of the width of a single crystal unit. The resolution of an image formed by the PET detector is related to the width value of the gap, and the smaller the width of the gap is, the higher the resolution of the image is; that is to say different sizes of the shielding means 3 enable the resolution of the detector to be increased by different factors. For example, if the width of the gap is 1/4 times the width of a single crystal unit, the number of imaging operations is two, the two images are complementary, and the resolution of each image is 4 times the resolution of the image without the shielding mechanism 3, so that after the two images are fused, the resolution of the final overall image is 4 times the resolution of the original image without the shielding mechanism 3.

It should be noted that, in other cases, the width of the gap may not be equal to the width of the shielding strip 32, and assuming that the sum of the widths of one gap and one shielding strip 23 is a, the width of the gap may be a/3, a/4, a/5, a/6, a/7, a/8, etc. For example, if the width of the gap is a/5, the blocking mechanism 3 needs to be moved four times in sequence, and a distance of a/5 for each movement, five PET images are obtained in total before and after the movement, and the five PET images are fused, so that a whole PET image of the target object can be obtained. The invention greatly improves the resolution of the PET detector, improves the image quality and reduces the production cost on the premise of not changing the crystal size.

Example two

As shown in fig. 4 to 6, the present embodiment provides another PET detector, which is substantially the same as the PET detector of the first embodiment except that: the specific arrangement of the shielding mechanism 3 and the adjusting mechanism 4 is different.

In this embodiment, two ends of the shielding strips 32 in the shielding mechanism 3 are respectively connected to the support rings 31 at the two ends, specifically, the length direction of each shielding strip 32 is the same as the axial direction of the support ring 31, that is, each shielding strip 32 extends along the axial direction of the support ring 31; and the plurality of shielding strips 32 are uniformly distributed at intervals along the circumferential direction of the shielding mechanism 3 to ensure the uniformity of the shielding mechanism 3 for gamma rays, thereby obtaining a PET image with higher quality. The plurality of shielding bars 32 form a grid structure, and a gap is provided between two adjacent shielding bars 32 in the circumferential direction, and the width of the gap is smaller than the width of a single crystal unit in the crystal array 21.

Meanwhile, the adjusting mechanism 4 of the embodiment includes a motor and a transmission component, the transmission component may be a gear and a gear ring which are engaged with each other, wherein the gear is connected with the output end of the motor and is used for rotating under the driving of the motor; the gear wheel drives the gear ring to rotate, so that the shielding mechanism 3 rotates along the circumferential direction of the support ring 31, and the circumferential distance of the shielding mechanism 3 should be consistent with the width value of the gap. When the detector detects, firstly, the shielding mechanism 3 obtains a first PET image at an initial position, then the shielding mechanism 3 is controlled to rotate for a preset distance (the width of a gap) along the circumferential direction of the support ring 31, so that a crystal which is not shielded by the shielding mechanism 3 is shielded, the original shielded crystal starts to receive gamma rays, a second PET image which is complementary with the first PET image is obtained, and finally, images obtained in two times are fused to obtain a final integral image with higher resolution.

EXAMPLE III

This embodiment provides a PET detector which is substantially the same as the PET detectors of the first and second embodiments, except that: the specific arrangement of the shielding mechanism 3 and the adjusting mechanism 4 is different.

In the present embodiment, a plurality of shielding bars 32 in the shielding mechanism 3, wherein a part of the shielding bars 32 extends along the circumferential direction of the supporting ring 31, and another part of the shielding bars 32 extends along the axial direction of the supporting ring 31, so as to form a grid-like structure, and the gap portion in the grid-like structure is the gap of the present embodiment, and the size (preferably the cross-sectional area) of the gap should be smaller than the size (preferably the cross-sectional area) of a single crystal unit in the crystal array 21.

The adjusting mechanism 4 of the present embodiment can drive the shielding mechanism 3 to move along the axial direction of the supporting ring 31, and can also drive the shielding mechanism 3 to rotate along the circumferential direction of the supporting ring 31. Specifically, the cylinder can drive the shielding mechanism 3 to move axially along the support ring 31, and the motor and gear set structure can drive the shielding mechanism 3 to rotate along the circumferential direction of the support ring 31, so that the shielding mechanism 3 can be independently and flexibly adjusted in different directions.

When the detector is used for detection, the shielding mechanism 3 is firstly enabled to obtain a first PET image at an initial position, then the shielding mechanism 3 is controlled to move for a preset distance along the axial direction to obtain a second PET image, then the shielding mechanism 3 is controlled to rotate for the preset distance along the circumferential direction to obtain a third PET image, and finally the shielding mechanism 3 is controlled to move for the preset distance along the axial direction to obtain a fourth PET image. The preset distance refers to the width of the gap, and the embodiment should ensure that the width of the shielding strip 32 in the grid-shaped grating is the same as the width of the gap. Through the four detections, all the crystal units in all the crystal arrays 21 in the crystal array can receive gamma rays, and the first PET image, the second PET image, the third PET image and the fourth PET image are fused to obtain a final overall image with high resolution.

Example four

The embodiment provides a PET system, which comprises a tracer injection unit, a detector control unit, a tracer signal separation unit and a PET detector according to any one of the above embodiments, wherein the PET detector is in signal connection or electrical connection with the detector control unit. Specifically, the tracer injection unit is used for sequentially injecting the tracer to the organism to be detected within a preset interval time; the detector control unit is used for controlling the PET detector to collect gamma rays emitted by the tracer in the organism to be detected from different angles; and the tracer signal separation unit is used for carrying out separation treatment on the gamma rays radiated by the tracer so as to obtain a PET image corresponding to the tracer. In the embodiment, the shielding mechanism is additionally arranged in the detector, so that PET images of organisms to be detected can be obtained in a graded manner, and then a tracer signal separation unit fuses a plurality of different PET images to generate a fused reconstructed image. The PET system effectively improves the resolution of the PET detector, improves the imaging quality and improves the accuracy of disease diagnosis on the premise of not changing the crystal size.

EXAMPLE five

The present embodiment provides a PET detection method using the PET detector in the first embodiment or the second embodiment, the PET detection method including the steps of:

s1: adjusting the initial position of the shielding mechanism 3 in the PET detector through the adjusting mechanism 4 to shield a part of the surface of the crystal array 21, and performing primary detection on the target detection object after adjustment to obtain a first PET image, wherein the first PET image only displays a part of information of the target detection object;

s2: the position of the shielding mechanism 3 is changed through the adjusting mechanism 4 to shield the surface of the rest part of the crystal array 21, and the target detection object is detected again to obtain a second PET image;

specifically, for the PET detector in the first embodiment, the adjusting mechanism 4 drives the shielding mechanism 3 to move a certain distance along the axial direction of the support ring 31, so as to obtain a second PET image complementary to the first PET image;

for the PET detector in the second embodiment, the adjusting mechanism 4 drives the shielding mechanism 3 to rotate a certain distance along the circumferential direction of the support ring 31, so as to obtain a second PET image complementary to the first PET image;

The detection method utilizes the shielding mechanism in the PET detector to detect the target detection object twice, thereby effectively improving the resolution of the PET detector and improving the imaging quality on the premise of not changing the crystal size.

EXAMPLE six

The present embodiment provides a PET detection method using the PET detector in the third embodiment, the PET detection method includes the following steps:

s1: adjusting the initial position of the shielding mechanism 3 in the PET detector through the adjusting mechanism 4 to shield the first part of the surface of the crystal array 21, and performing primary detection on the target detection object after adjustment to obtain a first PET image, wherein the first PET image only displays part of information of the target detection object;

s2: the adjusting mechanism 4 drives the shielding mechanism 3 to move for a certain distance along the axial direction of the support ring 31, so as to shield the second part surface of the crystal array 21, and detect the target detection object again, so as to obtain a second PET image;

s3: the adjusting mechanism 4 drives the shielding mechanism 3 to rotate for a certain distance along the circumferential direction of the support ring 31, so as to shield the third part surface of the crystal array 21, and detect the target detection object again to obtain a third PET image;

s4: then the adjusting mechanism 4 drives the shielding mechanism 3 to axially move for a certain distance along the support ring 31, so as to shield the surface of the rest part of the crystal array 21, and detect the target detection object again, so as to obtain a fourth PET image;

The detection method utilizes the shielding mechanism in the PET detector to detect the target detection object four times, thereby effectively improving the resolution of the PET detector and improving the imaging quality on the premise of not changing the crystal size.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A PET detector, comprising:

a PET ring (1);

a PET detection mechanism (2) mounted to an inner surface of the PET ring (1), the PET detection mechanism (2) comprising a crystal array (21); characterized in that the PET detector further comprises:

the shielding mechanism (3) covers the surface of the crystal array (21) far away from the PET ring (1), a grating is arranged on the shielding mechanism (3), and the gap size of the grating is smaller than the size of a single crystal unit in the crystal array (21); and

the adjusting mechanism (4) is fixed on the PET ring (1) and connected with the shielding mechanism (3), and the adjusting mechanism (4) can drive the shielding mechanism (3) to move so as to adjust the shielding position of the surface of the crystal array (21) of the shielding mechanism (3).

2. The PET detector according to claim 1, characterized in that the shielding mechanism (3) comprises a support ring (31) and a plurality of shielding strips (32) arranged in the support ring (31), the support ring (31) is connected with the adjusting mechanism (4), the support ring (31) is parallel or coaxial with the axis direction of the PET ring (1), and the plurality of shielding strips (32) form the grid.

3. The PET detector according to claim 2, characterized in that the shielding strip (32) extends in the circumferential direction of the support ring (31), and the adjusting mechanism (4) can drive the shielding mechanism (3) to move in the axial direction of the support ring (31).

4. The PET detector according to claim 2, characterized in that the shielding strip (32) extends in the axial direction of the support ring (31), and the adjusting mechanism (4) can drive the shielding mechanism (3) to rotate in the circumferential direction of the support ring (31).

5. The PET detector according to claim 2, wherein a part of the plurality of shielding strips (32) is arranged to extend in a circumferential direction of the support ring (31), and another part of the plurality of shielding strips (32) is arranged to extend in an axial direction of the support ring (31) to form a grid-like structure; the adjusting mechanism (4) can drive the shielding mechanism (3) to axially move along the support ring (31) and rotate along the circumferential direction of the support ring (31).

6. PET detector according to claim 3 or 4, characterized in that a plurality of the shielding strips (32) are evenly distributed over the support ring (31).

7. PET detector according to any one of claims 1-5, characterized in that the material of the shielding means (3) is one or more of iron, steel, lead, tungsten or copper.

8. A PET system comprising a detector control unit, characterized in further comprising PET detectors according to any of claims 1-7, the PET detectors being connected to the detector control unit.

9. A PET detection method using the PET detector of any one of claims 3, 4, 6 or 7, comprising:

s1: adjusting the initial position of a shielding mechanism (3), shielding a part of the surface of the crystal array (21), and carrying out primary detection on a target detection object to obtain a first PET image;

s2: changing the position of the shielding mechanism (3), shielding the surface of the rest part of the crystal array (21), and detecting the target detection object again to obtain a second PET image;

10. A PET detection method using the PET detector of claim 5 or 7, comprising:

s1: adjusting the initial position of a shielding mechanism (3), shielding the first part surface of the crystal array (21), and carrying out primary detection on a target detection object to obtain a first PET image;

s2: changing the position of the shielding mechanism (3) along the axial direction of the PET ring (1), shielding a second part of the surface of the crystal array (21), and detecting a target detection object again to obtain a second PET image;

s3: changing the position of the shielding mechanism (3) along the circumferential direction of the PET ring (1), shielding the third part surface of the crystal array (21), and detecting the target detection object again to obtain a third PET image;

s4: changing the position of the shielding mechanism (3) along the axial direction of the PET ring (1), shielding the surface of the rest part of the crystal array (21), and detecting the target detection object again to obtain a fourth PET image;