CN114587398A - Device for single photon emission tomography and projection data processing method - Google Patents

Device for single photon emission tomography and projection data processing method Download PDF

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CN114587398A
CN114587398A CN202210256815.0A CN202210256815A CN114587398A CN 114587398 A CN114587398 A CN 114587398A CN 202210256815 A CN202210256815 A CN 202210256815A CN 114587398 A CN114587398 A CN 114587398A
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hole
projection data
aliasing
projection
region
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CN114587398B (en
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孙立风
吕振雷
马天予
刘辉
刘伟
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China Nuclear Energy Tianjin Equipment Co ltd
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China Nuclear Energy Tianjin Equipment Co ltd
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Abstract

The embodiment of the invention provides a device for single photon emission tomography and a processing method of projection data, wherein the device comprises a collimator and a shielding mechanism, the collimator comprises a receiving part and a shielding part, at least two through holes are formed on the surface of the receiving part in a concave mode, an accommodating cavity is formed by the shielding part surrounding the receiving part, rays enter the accommodating cavity through the through holes, and the shielding mechanism is movably arranged in the accommodating cavity and used for shielding the rays, limiting the projection range of the through holes, dividing the projection of each through hole, avoiding artifacts in a reconstructed image caused by the aliasing of the projection of the through holes, ensuring the integrity of an imaging view field and solving the problem that the imaging view field of each through hole is lost.

Description

Device for single photon emission tomography and projection data processing method
Technical Field
The invention relates to the technical field of Single Photon Emission Computed Tomography (SPECT), in particular to a device for single photon emission tomography and a processing method of projection data.
Background
In single photon emission tomography, a collimator member needs to be placed between the human body and the detector. The multi-pinhole collimator is one of the collimators commonly used clinically at present, and the multi-pinhole collimator is generally designed into a round hole or an elliptical hole, and in order to improve the detection efficiency as much as possible in the design process, the detection area of the detector is fully utilized, so that a certain amount of aliasing exists in the projection areas of different pinholes on the detector, the imaging visual field of each pinhole can be lost, and certain artifacts appear in the final image.
Disclosure of Invention
In view of the defects of the prior art, the present invention aims to provide an apparatus and a method for processing projection data, which aim to solve the problem that the imaging field of view of each through hole in the multi-pinhole collimator in the prior art is lost.
An embodiment of the present invention provides an apparatus for single photon emission tomography, including: the collimator comprises a receiving part and a shielding part, the receiving part comprises at least two through holes, the through holes are arranged on the surface of the receiving part at intervals, the receiving part is used for receiving rays through the through holes, and the shielding part surrounds the receiving part to form an accommodating cavity; and the shielding mechanism is movably arranged in the accommodating cavity and is used for shielding rays.
According to one aspect of the invention, the shutter mechanism includes at least two shutter members, each of which moves independently within the accommodating chamber.
According to one aspect of the invention, the shutter member is rotatably and/or translationally disposed within the receiving cavity.
According to an aspect of the invention, the apparatus further comprises a detector comprising a detection surface for receiving the radiation, the detection surface being arranged towards the receiving portion such that the radiation passing through the through hole is imaged at the detection surface.
On the other hand, the invention also provides a processing method of projection data, which comprises the steps that a shielding mechanism is arranged in a collimator, the collimator comprises a receiving part and a shielding part, the receiving part comprises a first through hole and a second through hole, at least parts of projections of the first through hole and the second through hole on a detection surface are overlapped to form an aliasing area, the receiving part is used for receiving rays, the shielding part surrounds the receiving part to form an accommodating cavity, and the shielding mechanism is movably arranged in the accommodating cavity;
enabling the shielding mechanism to shield the projection of the first through hole in the aliasing region, and acquiring projection data of the first through hole and the second through hole in the aliasing region as C1 within a first period of time t 0;
enabling the shielding mechanism to shield the projection of the second through hole in the aliasing region, and acquiring the projection data of the first through hole and the second through hole in the aliasing region as C2 in a second period t 0;
enabling the shielding mechanism to shield the projection of the first through hole in the aliasing area, and in a third time period
Figure BDA0003548921660000021
Collecting projection data P3 on the detection surface through the first through hole and the second through hole within time;
the shielding mechanism shields the projection of the second through hole in the aliasing area in the fourth time period
Figure BDA0003548921660000022
In time, acquiring projection data P4 on a detection surface through the first through hole and the second through hole by using a probe;
partial acquisition data of the first via and the second via for a time (t-2t0) is determined from the projection data P3 and the projection data P4.
According to an aspect of the invention, the data processing method further comprises:
projection data of the first via and the second via in the time without aliasing are determined (t-2t0) from the partially acquired data.
According to one aspect of the invention, the step of determining projection data of the first and second vias in the non-aliasing condition from the partially acquired data comprises:
the projection data P3 and the projection data P4 satisfy the following relational expression:
P3＝PA3∪PC3∪PB3 (1)
P4＝PA4∪PC4∪PB4 (2)
wherein, PAFor the unaliased region of the first via on the detector, PBFor unaliased areas of the second via on the detector, PCAn aliasing region being a first via and a second via;
PA∪PCis the projection area of the first through hole on the detector, PB∪PCThe projection area of the second through hole on the detector;
PC3is data of an aliasing region in projection data P3, PA3Data for unaliased regions in the first via, PB3Data for unaliased areas in the second via, PC4Is data of an aliasing region in projection data P4, PA4Data for unaliased regions in the first via, PB4Data for an unaliased region in the second via;
during time (t-2 × t0), the projection data of the first via and the second via under the condition of no aliasing satisfy the following relation:
Figure BDA0003548921660000031
Figure BDA0003548921660000032
wherein, PFirst through holeProjection data for the first via in (t-2 × t0) time without aliasing, PSecond through holeProjection data for the second via at time (t-2 × t0) without aliasing.
According to an aspect of the present invention, in the step of causing the shielding mechanism to shield the projection of the first through hole in the aliasing region, acquiring projection data of the first through hole and the second through hole in the aliasing region as C1 in a first period t0, further includes: acquiring projection data P1 on a detection surface through the first through hole and the second through hole;
in the step of causing the shielding mechanism to shield the projection of the second through hole in the aliasing region, acquiring projection data of the first through hole and the second through hole in the aliasing region as C2 in a second time period t0, the method further includes: acquiring projection data P2 on a detection surface through the first through hole and the second through hole;
the projection data processing method further includes:
replacing the projection data P3 in the expression (1) with projection data P1, and replacing the projection data P4 in the expression (2) with projection data P2;
in (2 × t0), the projection data of the first via and the second via in the case of no aliasing satisfy the following relation:
P′first through hole＝(PA1+PA2)∪C2
P′Second through hole＝(PB1+PB2)∪C1
Wherein, P'First through holeIs the projection data with no aliasing for the first via in time (2 x t0), P'Second through holeProjection data for the second via at (2 × t0) time without aliasing;
let PFirst through hole+P’First through holeObtaining complete projection data of the first through hole under the condition of no aliasing within t time;
let PSecond through hole+P’Second through holeAnd obtaining complete projection data of the second through hole in the t time under the condition of no aliasing.
According to an aspect of the present invention, the receiving unit further includes a third through hole, and an aliasing area exists in a projection on the detection surface between the third through hole and the second through hole, on a side of the second through hole away from the first through hole, and the data processing method further includes:
complete projection data of the second via and the third via without aliasing is determined.
According to one aspect of the invention, the data acquisition method further comprises:
calculating when the shielding mechanism is in each state
Figure BDA0003548921660000041
And
Figure BDA0003548921660000042
and (4) determining the position of the shielding mechanism according to the proportion.
In the device, the device comprises a collimator and a shielding mechanism, wherein the collimator comprises a receiving part and a shielding part, at least two through holes are formed in the surface of the receiving part in a penetrating mode, the shielding part surrounds the receiving part to form an accommodating cavity, and rays enter the accommodating cavity through the through holes. The shielding mechanism is movably arranged in the accommodating cavity, the shielding mechanism can limit the projection range of the through holes through shielding rays, the shielding mechanism can more accurately shield the projection of each through hole in an aliasing region through moving, the projection of each through hole is separated, the aliasing region does not exist any more, so that the obtained projection image of a single through hole is more accurate, the artifact in the reconstructed image caused by aliasing in the projection of the through holes is avoided, the integrity of the imaging field of view is ensured, and the problem that the imaging field of view of each through hole is lost is solved.
Drawings
Other features, objects, and advantages of the present application will become apparent from the following detailed description of non-limiting embodiments thereof, when read in conjunction with the accompanying drawings, in which like or similar reference characters identify the same or similar features.
FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a detection plane provided by an embodiment of the present invention;
FIG. 3 is a schematic projection view of a first via and a second via provided by an embodiment of the present invention;
fig. 4 is a flowchart illustrating a method for processing projection data according to an embodiment of the present invention;
fig. 5 is a flowchart illustrating a method for processing projection data according to an embodiment of the present invention.
Description of reference numerals:
10. a collimator; 20. a detector; 30. a shielding mechanism; 40. a ray;
100. a receiving section; 101. a through hole; 101a, a first through hole; 101b, a second through hole; 110. a shielding part; 120. an accommodating chamber;
200. detecting a surface; 201. an aliasing region;
300. a shielding member.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. In the drawings and the following description, at least some well-known structures and techniques have not been shown in detail in order to avoid unnecessarily obscuring the present invention; also, the dimensions of some of the structures may be exaggerated for clarity. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
In the description of the present invention, it should be noted that unless otherwise specified, the terms "upper", "lower", "left", "right", "inner", "outer", and the like, indicate orientations or positional relationships only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The directional terms appearing in the following description are intended to be illustrative in all directions, and are not intended to limit the specific construction of embodiments of the present invention. In the description of the present invention, it should also be noted that, unless otherwise explicitly stated or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be directly connected or indirectly connected. The specific meaning of the above terms in the present invention can be understood as appropriate to those of ordinary skill in the art.
For a better understanding of the present invention, the apparatus of an embodiment of the present invention is described in detail below with reference to fig. 1 to 3.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an apparatus for single photon emission tomography according to an embodiment of the present invention.
According to the present invention there is provided apparatus comprising: the collimator 10, the collimator 10 includes a receiving portion 100 and a shielding portion 110, the receiving portion 100 includes at least two through holes 101, the through holes 101 are arranged on the surface of the receiving portion 100 at intervals, the receiving portion 100 is used for receiving the rays 40 through the through holes 101, and the shielding portion 110 forms an accommodating cavity 120 around the receiving portion 100; the shielding mechanism 30, the shielding mechanism 30 is movably disposed in the accommodating chamber 120, and the shielding mechanism 30 is used for shielding the ray 40.
In the device of the embodiment of the invention, the device comprises a collimator 10 and a shielding mechanism 30, the collimator 10 comprises a receiving part 100 and a shielding part 110, the shielding part 110 forms a containing cavity 120 around the receiving part 100, at least two through holes 101 are formed on the surface of the receiving part 100 in a penetrating manner, and rays 40 enter the containing cavity 120 through the through holes 101. Shelter from mechanism 30 and can move and set up in holding chamber 120, shelter from mechanism 30 and remove in holding chamber 120, shelter from mechanism 30 and can more accurately shelter from the projection of each through-hole 101 in aliasing region 201 through removing, make the projection of each through-hole 101 separate, no longer there is aliasing region 201, thereby make the projection image of single through-hole 101 that obtains more accurate, avoid the artifact in the rebuilt image that through-hole 101 projection aliasing brought, ensure the integrality in the formation of image field, the problem that every through-hole 101 formation of image field of vision can appear the disappearance has been solved.
In some alternative embodiments, the shielding mechanism 30 includes at least two shielding members 300, and each shielding member 300 moves independently within the accommodating chamber 120.
In these alternative embodiments, the shielding member 300 moves in the accommodating chamber 120 to shield the ray 40 passing through the through hole 101. A plurality of parts 300 that shelter from move to different positions in holding chamber 120 as required to shelter from the ray 40 to a plurality of through-holes 101 simultaneously, restrict the projection scope of a plurality of through-holes 101, avoid a plurality of through-holes 101 projection aliasing, make the projection image of each through-hole that obtains more accurate.
In some alternative embodiments, the shutter member 300 is rotatably and/or translationally disposed within the receiving cavity 120.
In these alternative embodiments, the shielding component 300 moves in the accommodating cavity 120 by rotation and/or translation, so that the shielding area or position of the shielding component 300 can be changed, and further the projection range of each through hole 101 can be changed, and the area occupied by different through holes 101 can be arbitrarily divided in the aliasing area 201 by moving the shielding component 300.
In some alternative embodiments, the apparatus further comprises a detector 20, the detector 20 comprising a detection surface 200 for receiving the radiation 40, the detection surface 200 being arranged towards the receiving portion 100 such that the radiation 40 passing through the through hole 101 is imaged at the detection surface 200.
In these alternative embodiments, the ray 40 passes through the through hole 101 of the receiving portion 100 to form a projection on the detector 20, the detection surface 200 faces the receiving portion 100, the ray 40 is imaged on the detection surface 200, and according to the projection formed on the detection surface 200, the shielding range of the shielding component 300 can be changed in real time, so as to flexibly adjust the area occupied by the aliasing region 201 on the detection surface 200 in projecting the corresponding through hole 101.
Referring to fig. 1 to 5, fig. 2 is a schematic structural diagram of a detection plane according to an embodiment of the present invention, fig. 3 is a schematic projection diagram of a first through hole 101a and a second through hole 101b according to an embodiment of the present invention, fig. 4 is a schematic flow chart of a method for processing projection data according to an embodiment of the present invention, and fig. 5 is a schematic flow chart of a method for processing projection data according to an embodiment of the present invention. A second embodiment of the present invention further provides a method for processing projection data, where the method is implemented by using the apparatus in any of the above embodiments, and the method includes:
step S1: a shutter mechanism 30 is provided within the collimator 10.
As described above, the collimator 10 includes the receiving portion 100 and the shielding portion 110, the receiving portion 100 includes the first through hole 101a and the second through hole 101b, projections of the first through hole 101a and the second through hole 101b on the detection plane 200 at least partially overlap to form the aliasing region 201, the receiving portion 100 is used for receiving the radiation 40, the shielding portion 110 forms the accommodating chamber 120 around the receiving portion 100, and the shielding mechanism 30 is movably disposed in the accommodating chamber 120.
Step S2: the shielding mechanism 30 shields the projection of the first through hole 101a on the aliasing region 201. During the first period t0, projection data C1 of the first via 101a and the second via 101b in the aliasing region 201 are acquired.
As described above, the projection obtained by the detection plane 200 is the complete projection of the second through hole 101b and the projection of the first through hole 101a without including the aliasing region 201, and at this time, the data obtained in step S2 is the complete projection data of the second through hole 101b and the projection data of the first through hole 101a without including the aliasing region 201, so that aliasing of the first through hole 101a and the second through hole 101b is avoided, and the obtained projection data is more accurate.
Step S3: the shielding mechanism 30 is made to shield the projection of the second through hole 101b in the aliasing region 201, and in the second period t0, the projection data C2 of the first through hole 101a, the second through hole 101b, the first through hole 101a and the second through hole 101b in the aliasing region 201 are acquired.
As described above, the projection obtained by the detection plane 200 is the complete projection of the first through hole 101a and the projection of the second through hole 101b not including the aliasing region 201, and at this time, the data obtained in step S3 is the complete projection data of the first through hole 101a and the projection data of the second through hole 101b not including the aliasing region 201, so that aliasing of the first through hole 101a and the second through hole 101b is avoided, and the obtained projection data is more accurate. Step S4: enabling the shielding mechanism to shield the projection of the first through hole 101a in the aliasing region, and enabling the shielding mechanism to shield the projection in the aliasing region in the third time period
Figure BDA0003548921660000081
During time, projection data P3 on the detection surface through the first through hole 101a and the second through hole 101b are acquired.
As described above, the projection obtained by the detection plane 200 is the complete projection of the second through hole 101b and the projection of the first through hole 101a without including the aliasing region 201, and at this time, the data obtained in step S4 is the complete projection data of the second through hole 101b and the projection data of the first through hole 101a without including the aliasing region 201, so that aliasing of the first through hole 101a and the second through hole 101b is avoided, and the obtained projection data is more accurate.
Step S5: the shielding mechanism shields the projection of the second through hole 101b in the aliasing region in the fourth time period
Figure BDA0003548921660000082
In time, projection data P4 on the detection surface through the first through hole 101a and the second through hole 101b is acquired.
As described above, the projection obtained by the detection plane 200 is the complete projection of the first through hole 101a and the projection of the second through hole 101b not including the aliasing region 201, and at this time, the data obtained in step S5 is the complete projection data of the first through hole 101a and the projection data of the second through hole 101b not including the aliasing region 201, so that aliasing of the first through hole 101a and the second through hole 101b is avoided, and the obtained projection data is more accurate.
The sequence of step S2 and step S3 is not limited. Step S2 may be implemented prior to step S3, or step S3 may be implemented prior to step S2. The sequence of step S4 and step S5 is not limited. Step S4 may be implemented prior to step S5, or step S5 may be implemented prior to step S4. As long as it is ensured that the corresponding acquisition data can be obtained.
Step S6: the partial acquisition data of the first and second through holes 101a and 101b in the time (t-2t0) is determined from the projection data P3 and the projection data P4.
In the above step S2, during the first period t0, when the shielding mechanism 30 shields the projection of the first through hole 101a on the aliasing region 201, the obtained projection data is the projection data of the second through hole 101b and the first through hole 101a not including the aliasing region 201, and at this time, the projection data of the first through hole 101a on the aliasing region 201 cannot be obtained. Similarly, in step S3, in the second period t0, when the shielding mechanism 30 shields the projection of the second through hole on the aliasing region 201, the obtained projection data is the projection data of the first through hole 101a and the second through hole 101b not including the aliasing region 201, and at this time, the projection data of the second through hole 101b on the aliasing region 201 cannot be obtained. The duration of the first period t0 and the second period t0 is t 0.
In steps S4 and S5, the projection data P3 and the projection data P4 are acquired by temporally allocating according to the ratio of C1 to C2, the projection data P3 is the projection data P3 in which the second through hole 101b and the first through hole 101a do not include the aliasing region 201, the projection data P4 is the projection data P4 in which the first through hole 101a and the second through hole 101b do not include the aliasing region 201, and the time is allocated according to the ratio of C1 to C2, so that the acquisition efficiency is improved, and the image quality is improved.
As described above, from the obtained partial acquisition data, projection data of the first and second through holes 101a and 101b in the (t-2t0) time without aliasing can be determined, which is used to determine respective complete projection data of the first and second through holes 101a and 101b in the t time, so as to reconstruct a complete image. Therefore, in the embodiment of the present invention, during the data acquisition process, the shielding mechanism 30 is made to shield the projections of the first through hole 101a and the second through hole 101b in the aliasing region 201, respectively, then the projection data of the first through hole 101a and the second through hole 101b on the detection plane 200 are acquired, the partial acquisition data in the (t-2t0) time is determined according to the projection data, and thus the projection data of each through hole of the first through hole 101a and the second through hole 101b in the (t-2t0) time without aliasing is determined according to the partial acquisition data. The shielding mechanism 30 shields the projections of the first through hole 101a and the second through hole 101b in the aliasing region 201, so that artifacts in a reconstructed image caused by aliasing of the projections of the through holes 101 are avoided, the loss of an imaging visual field is avoided, and the integrity of the imaging visual field is ensured.
In some optional embodiments, the projection data processing method further includes step S7: projection data of the first via 101a and the second via 101b in the time without aliasing are determined (t-2t0) from the partially acquired data.
In these alternative embodiments, the shielding component 300 is used to respectively shield the projections of the first via 101a and the second via 101b in the aliasing region 201, collect part of the collected data in the (t-2 × t0) time, and determine the projection data of the first via 101a and the second via 101b in the (t-2 × t0) time without aliasing according to the part of the collected data, so as to further avoid artifacts in the reconstructed image caused by aliasing of the projections of the vias 101, avoid the lack of the imaging field of view, and ensure the integrity of the imaging field of view.
Referring to fig. 3, in some alternative embodiments, step S7 further includes:
the projection data P3 and the projection data P4 satisfy the following relational expression:
P3＝PA3∪PC3∪PB3 (1)
P4＝PA4∪PC4∪PB4 (2)
wherein, PAIs the unaliased region, P, of the first via 101a on the detector 20BIs the unaliased area, P, of the second via 101b on the detector 20CAn aliasing region 201 which is a first via hole 101a and a second via hole 101 b;
PA∪PCis the projection area, P, of the first through hole 101a on the probe 20B∪PCIs the projection area of the second through hole 101b on the detector 20;
PC3is the data of aliasing region 201 in projection data P3, PA3Is data of the unaliased region in the first via 101a, PB3Data of unaliased region, P, in the second via 101bC4Is the data of aliasing region 201 in projection data P4, PA4Is data of the unaliased region in the first via 101a, PB4Data of an unaliased region in the second via 101 b;
during the time (t-2 × t0), the projection data of the first via 101a and the second via 101b in the case of no aliasing satisfy the following relation:
Figure BDA0003548921660000101
Figure BDA0003548921660000102
wherein, PFirst through holeWithout aliasing for the first via 101a during time (t-2 × t0)Projection data of PSecond through holeThe projection data of the second via 101b at time (t-2 × t0) without aliasing is obtained.
In these alternative embodiments, PA、PBAnd PCThe projection data of the region can be directly obtained according to the spatial position projected on the detection surface 200, the projection data of the aliasing region 201 in the (t-2 × t0) time is corrected according to the acquisition time, and the projection data of the aliasing region 201 missing from the first through hole 101a and the second through hole 101b in the step S4 and the step S5 can be obtained, so that the complete projection data of each through hole 101 in the (t-2 × t0) time under the aliasing-free condition can be obtained through calculation.
In some optional embodiments, in step S2, the method further includes: acquiring projection data P1 on the detection surface 200 through the first through hole 101a and the second through hole 101 b;
in step S3, the method further includes: acquiring projection data P2 on the detection surface 200 through the first through hole 101a and the second through hole 101 b;
the projection data processing method further includes:
step S8: replacing the projection data P3 in the expression (1) with the projection data P1, and replacing the projection data P4 in the expression (2) with the projection data P2; in the time (2 × t0), the projection data of the first via 101a and the second via 101b in the aliasing-free case satisfy the following relation:
P′first through hole＝(PA1+PA2)∪C2
P′Second through hole＝(PB1+PB2)∪C1
Wherein, P'First through holeIs the projection data, P 'of the first via 101a without aliasing during time (2 x t 0)'Second through holeProjection data without aliasing for the second via 101b during time (2 × t 0);
step S9: let PFirst through hole+P’First through holeObtaining complete projection data of the first through hole 101a in the time t under the condition of no aliasing;
step S10: let PSecond through hole+P’Second through holeObtaining no mixing of the second through hole 101b within t timeComplete projection data in case of a stack.
As described above, in step S8, the projection data of the aliasing region 201 in the time (2 × t0) is corrected in accordance with the acquisition time, and the projection data of the aliasing region 201 missing from the first via 101a and the second via 101b in step S2 and step S3 can be obtained, so that the complete projection data in the case of no aliasing for each via 101 in the time (2 × t0) can be calculated. The obtained projection data P1 and P2 are accumulated in the projection data of the through hole 101 by the same method in the step S7, the step S9 obtains the complete projection data of the first through hole 101a in the time t under the condition of no aliasing, and the step S10 obtains the complete projection data of the first through hole 101a in the time t under the condition of no aliasing, that is, the complete projection data of all the through holes 101 under the condition of no aliasing are obtained, so that the image reconstruction is performed by using the conventional nuclear medicine image reconstruction algorithm, the final reconstructed image is obtained, and the loss of the imaging field of view is further avoided.
In some optional embodiments, the receiving portion 100 further includes a third through hole, and the projection on the detection surface 200 between the second through hole 101b and the side of the second through hole 101b facing away from the first through hole 101a has an aliasing region 201, and the data processing method further includes step S11: complete projection data of the second via 101b and the third via without aliasing is determined.
In these alternative embodiments, the shielding mechanism 30 is used to respectively shield the projections of the first through hole 101a, the second through hole 101b and the third through hole in the aliasing region 201, and the data is collected by using the probe, so as to determine the complete projection data of each through hole 101 under the aliasing-free condition, thereby realizing the projection data collection of the multiple through holes 101, and further ensuring the integrity of the imaging field of view.
In some optional embodiments, the data processing method further includes step S12:
in each state of the shielding mechanism 30, calculation is performed
Figure BDA0003548921660000121
And
Figure BDA0003548921660000122
the scale, the position of the shielding mechanism 30 is determined according to the scale.
In these alternative embodiments, the projection data is based on
Figure BDA0003548921660000123
And
Figure BDA0003548921660000124
the optimal shielding position of the shielding mechanism 30 is determined in proportion, so that an optimal acquisition scheme is ensured, the acquisition efficiency is improved, and the image quality is improved.
In accordance with the above embodiments of the present invention, these embodiments are not exhaustive and do not limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.

Claims (10)

1. An apparatus for single photon emission tomography, comprising:
the collimator comprises a receiving part and a shielding part, the receiving part comprises at least two through holes, the through holes are arranged on the surface of the receiving part at intervals, the receiving part is used for receiving rays through the through holes, and the shielding part forms an accommodating cavity around the receiving part;
and the shielding mechanism is movably arranged in the accommodating cavity and is used for shielding the ray.
2. The apparatus of claim 1, wherein the shutter mechanism comprises at least two shutter members, each of the shutter members independently movable within the receiving cavity.
3. A device according to claim 3, wherein the shutter member is rotatably and/or translationally disposed within the receiving cavity.
4. The apparatus of claim 1, further comprising a detector including a detection surface for receiving the radiation, the detection surface being disposed toward the receiving portion such that the radiation passing through the through-hole is imaged at the detection surface.
5. A method for processing projection data, comprising:
the shielding mechanism is arranged in the collimator, the collimator comprises a receiving part and a shielding part, the receiving part comprises a first through hole and a second through hole, projections of the first through hole and the second through hole on a detection surface are at least partially overlapped to form an aliasing region, the receiving part is used for receiving rays, the shielding part surrounds the receiving part to form a containing cavity, and the shielding mechanism is movably arranged in the containing cavity;
enabling the shielding mechanism to shield the projection of the first through hole in the aliasing region, and acquiring projection data of the first through hole and the second through hole in the aliasing region as C1 in a first period t 0;
enabling the shielding mechanism to shield the projection of the second through hole in the aliasing region, and acquiring projection data of the first through hole and the second through hole in the aliasing region as C2 in a second t0 time period;
enabling the shielding mechanism to shield the projection of the first through hole in the aliasing region, and enabling the shielding mechanism to shield the projection of the first through hole in the aliasing region in a third time period
Figure FDA0003548921650000011
Acquiring projection data P3 on the detection surface through the first through hole and the second through hole within time;
enabling the shielding mechanism to shield the projection of the second through hole in the aliasing region in a fourth time period
Figure FDA0003548921650000021
Acquiring projection data P4 on the detection surface through the first through hole and the second through hole within time by using the probe;
determining partial acquisition data of the first and second vias over a time (t-2t0) from the projection data P3 and the projection data P4.
6. The projection data processing method of claim 5, further comprising
Determining (t-2t0) projection data of the first via and the second via without aliasing during the time from the partially acquired data.
7. The projection data processing method of claim 5, wherein the step of determining (t-2t0) projection data of the first via and the second via in an aliasing-free case in time from the partially acquired data comprises:
the projection data P3 and the projection data P4 satisfy the following relational expression:
P3＝PA3∪PC3∪PB3 (1)
P4＝PA4∪PC4∪PB4 (2)
wherein, PAFor the unaliased region of the first via on the detector, PBFor the unaliased region of the second via on the detector, PCThe aliasing regions for the first and second vias;
PA∪PCis the projection area, P, of the first through hole on the detectorB∪PCThe projection area of the second through hole on the detector is set;
PC3is the data of the aliasing region in the projection data P3, PA3Data of the unaliased region in the first via, PB3For the non-aliasing in the second viaData of the region, PC4Is the data of the aliasing region in the projection data P4, PA4Data of the unaliased region in the first via, PB4Data for the unaliased region in the second via;
at time (t-2 × t0), projection data of the first via and the second via under no aliasing satisfy the following relation:
Figure FDA0003548921650000022
Figure FDA0003548921650000023
wherein, PFirst through holeProjection data P for the first via in the (t-2 × t0) time without aliasingSecond through holeProjection data without aliasing for the second via during the (t-2 × t0) time.
8. The projection data processing method according to claim 7,
in the step of causing the shielding mechanism to shield the projection of the first through hole in the aliasing region, acquiring projection data of the first through hole and the second through hole in the aliasing region as C1 in a first period t0, further comprising: acquiring projection data P1 on the detection surface through the first through hole and the second through hole;
in the step of causing the shielding mechanism to shield the projection of the second through hole in the aliasing region, acquiring projection data of the first through hole and the second through hole in the aliasing region as C2 in a second t0 time, further comprising: acquiring projection data P2 on the detection surface through the first through hole and the second through hole;
the projection data processing method further includes:
replacing the projection data P3 in the formula (1) with the projection data P1, and replacing the projection data P4 in the formula (2) with the projection data P2;
at (2 × t0), projection data of the first via and the second via under the condition of no aliasing satisfy the following relation:
P’first through hole＝(PA1+PA2)∪C2
P’Second through hole＝(PB1+PB2)∪C1
Wherein, P'First through holeIs the projection data of the first via in the (2 x t0) time without aliasing, P'Second through holeProjection data without aliasing for the second via during the (2 × t0) time;
let PFirst through hole+P’First through holeObtaining complete projection data of the first through hole in the t time under the condition of no aliasing;
let PSecond through hole+P’Second through holeAnd obtaining complete projection data of the second through hole in the t time under the condition of no aliasing.
9. The projection data processing method according to claim 8, wherein the receiving section further includes a third through hole on a side of the second through hole facing away from the first through hole and between which the aliasing region exists in projection on the detection plane, the data processing method further comprising:
determining complete projection data of the second and third vias without aliasing.
10. The data acquisition method of claim 5, further comprising:
calculating when the shielding mechanism is in each state
Figure FDA0003548921650000041
And
Figure FDA0003548921650000042
and determining the position of the shielding mechanism according to the proportion.
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