CN104408756A

CN104408756A - PET image reconstruction method and apparatus

Info

Publication number: CN104408756A
Application number: CN201410603993.1A
Authority: CN
Inventors: 赵大哲; 王军搏; 韩冬; 栗伟; 耿欢
Original assignee: Neusoft Corp
Current assignee: Neusoft Corp
Priority date: 2014-10-30
Filing date: 2014-10-30
Publication date: 2015-03-11
Anticipated expiration: 2034-10-30
Also published as: CN104408756B

Abstract

Disclosed in the invention is a positron emission computed tomography (PET) image reconstruction method. The method comprises the following steps that: according to list-mode data for PET reconstruction, space encoding data corresponding to coincidence event data in the list-mode data are determined, wherein the space encoding data consists of a first encoding unit, a second encoding unit, a third encoding unit, a fourth encoding unit, and a fifth encoding unit; all space encoding data are sorted according to a preset spatial order; and on the basis of the sorting result, all space encoding data are successively processed, thereby completing PET image reconstruction by an iteration reconstruction algorithm. In addition, the invention also discloses a PET image reconstruction apparatus.

Description

A kind of PET image reconstruction method and device

Technical field

The present invention relates to technical field of image processing, particularly relate to a kind of PET image reconstruction method and device.

Background technology

Current, positron emission tomography (Positron Emission Computed Tomography, being called for short PET) technology has been widely used in the important field of biomedical research such as tumour early detection, drug screening, and compare with traditional medical imaging modalities and there is obvious advantage.PET technology is by injecting the radiotracer with targeting in human body, and carries out annihilation photon acquisition of signal in vitro, and PET can reconstruct the space distribution of tracer agent, thus indirectly obtains the physiological metabolism information of human body.And often make PET image reconstruction effect show obvious difference based on different data modes and method for reconstructing, usually, the data memory format rebuild for PET is divided into (Sinogram) data of the sinogram in units of data for projection and to meet table schema (list-mode) data in units of event.

Due to sinogram data storage is data for projection, its data volume can increase along with the quantity of pet detector and increase, when in conjunction with flight time (Time of Flight is called for short TOF) information, sinogram data amount also can improve decades of times, and reconstruction time also can increase thereupon.For addressing this problem, conventional method uses the merging of the projection angle in fault plane, the merging of axial rings difference etc. to reduce the mode of data sampling to reduce sinogram data to the demand of storage space and the reconstruction speed improving iterative algorithm.But these methods can cause rebuilding image tangential spatial resolution or axial spatial resolution decline in various degree in fault plane.Rebuild for TOF-PET and then also will be divided into meeting event time difference some time intervals compared with Large space (time-bin) down-sampled process is carried out to temporal information, limit TOF and rebuild raising ability to imaging signal to noise ratio (S/N ratio).

Compared to the data layout of sinogram, the data of List-mode form then can be good at solving the problem.List-mode data layout, to the time sequencing meeting event according to PET system looks, by the data mode that the information such as the time of annihilation photon, energy, position store successively, the size of its data volume only and meet event count number relevant, can't increase along with the increase of detector cells quantity.Simultaneously, list-mode data can naturally be combined with TOF method for reconstructing, can carry out meticulousr time-bin and divide, thus remain all information of raw data, make to improve acquisition speed further, reduce drug dose, improve PET image quality and become possibility.

But the method for reconstructing based on list-mode data is also faced with that reconstruction speed is slow, reconstruction time obviously increases these problems along with the increase meeting event count.The conventional iterative method for reconstructing of List-mode data; maximum likelihood expectation maximization (the Maximum Like lihoodExpectation Maximization using sinogram data for projection; being called for short MLEM) reconstruction algorithm is extended to during the single PET meeting event rebuilds; but the reconstruction speed of this method slowly, cannot directly apply clinically.At present, the iteratively faster of list-mode data rebuilds order subset expectation maximization method (the Ordered Subsets Expectation Maximization of over-borrowing mirror based on sinogram data for projection, be called for short OSEM), by list-mode data are divided according to the time sequencing gathered, thus realize rebuilding based on the OSEM iteratively faster of time subset.Due to when TOF rebuilds, every bar projection line can only have small part to act on image space, and need whole piece projection line to be applied to image space unlike non-TOF reconstruction, in TOF rebuilds, use projection angle to merge, when the down-sampled methods such as axial rings difference merges reduce data space and improve reconstruction speed, the loss of spatial resolution in respective direction can be reduced, therefore, these class methods are applied in the TOF reconstruction of list-mode data by prior art, and the event that meets of the same space position is merged, make reconstruction time can not be subject to meeting the impact of event count increase.In addition, existing employing and sinogram data rebuild similar data ordering method, divide according to projecting direction by list-mode data, and adopt OSEM algorithm to rebuild, this method makes list-mode data spatially achieve sequential packet to a certain extent, can realize in theory than service time ordered subsets OSEM method rebuild speed faster.Except the optimization on reconstruction algorithm and improvement, prior art is also based on graphics processing unit (Graphic Processing Unit, be called for short GPU) hardware-accelerated method for reconstructing aspect also conduct in-depth research, in accelerated reconstruction, serve good effect.

The fast reconstructing method based on algorithm optimization introduced above can play certain accelerating effect in image reconstruction, but these methods still exist obvious deficiency in reconstruction speed.

Summary of the invention

In view of this, the fundamental purpose of the embodiment of the present invention is to provide a kind of PET image reconstruction method and device, to realize the object improving image reconstruction speed.

For achieving the above object, embodiments provide a kind of PET image reconstruction method, comprising:

According to the table schema list-mode data of rebuilding for PET, determine that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, described spatial encoding data comprises the first coding, the second coding, the 3rd coding, the 4th coding and the 5th coding;

All spatial encoding data are sorted according to pre-set space order;

Successively each spatial encoding data is processed according to ranking results, to complete PET image reconstruction by iterative reconstruction algorithm;

Wherein,

Described first is encoded to and meets direction encoding corresponding to the projecting direction of event in fault plane, and described fault plane is the annular section of detector rings;

Described second be encoded to described in meet regional code corresponding to the view field of event under described projecting direction, described view field detects the region between two probe units meeting event;

Described 3rd be encoded to described in meet ring difference coding corresponding to detector rings difference that event has, described detector rings difference for going through the difference of number of rings and 1, described in go through number of rings be the detector rings quantity that the described view field on fault plane axial direction goes through;

Described 4th is encoded to time-bin coding corresponding to the time-bin position that meets event described in generation, and described time-bin position is one in each time interval divided according to list-mode data time difference information in view field along described projecting direction;

Described 5th be encoded to described in meet the axial location of event in described time-bin position corresponding axis coding.

Preferably, be used for the list-mode data of PET reconstruction in described basis, before determining that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, also comprise:

If each detector rings comprises M probe unit, be then divided into meeting the projecting direction of event in described fault plane plant or M kind, and encode to obtain to often kind of projecting direction individual or M direction encoding;

When projecting direction is divided into kind time, the view field of the M-1 under same projection direction in described fault plane is encoded, to obtain M-1 regional code, when projecting direction is divided into M kind, by under same projection direction in described fault plane individual or individual view field encodes, to obtain individual or individual regional code;

If there is P the detector rings of placing successively side by side, then, on fault plane axial direction, the Q kind detector rings difference under same projection direction is encoded, to obtain Q ring difference coding, Q≤P;

Fault plane axial region is divided into the N number of time interval axially parallel with fault plane, and the N number of time interval under same projection direction is encoded, encode to obtain N number of time-bin;

Axial coding is carried out to the Z kind axis projection region with same probe ring difference RD under same projection direction, to obtain Z axially coding, Z=P-RD;

Wherein, M, q, P, N, Z are natural number.

Preferably, described all spatial encoding data to be sorted according to pre-set space order, comprising:

Be divided into same first data group by all spatial encoding data that equidirectional should be had to encode, and the first data group described in each is sorted according to the first preset order;

By in described first data group, same second data group is divided into all spatial encoding data that same area should be had to encode, and the second data group described in each is sorted according to the second preset order;

By in described second data group, same 3rd data group is divided into all spatial encoding data that identical ring difference should be had to encode, and the 3rd data group described in each is sorted according to the 3rd preset order;

By in described 3rd data group, same 4th data group is divided into all spatial encoding data that identical time-bin should be had to encode, and the 4th data group described in each is sorted according to the 4th preset order;

All spatial encoding data in described 4th data group are sorted according to the 5th preset order.Preferably, describedly successively each spatial encoding data to be processed according to ranking results, comprising:

Each spatial encoding data meeting event is obtained successively according to ranking results; The spatial encoding data that the spatial encoding data and upper meeting event if current meets event is different, then carry out forward direction and backwards projection in conjunction with flight time TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain; The spatial encoding data that the spatial encoding data and upper meeting event if current meets event is identical, then meet event forward projection using upper one or backwards projection result meets event forward projection or backwards projection result as current;

Or, obtain each spatial encoding data meeting event successively according to ranking results; For the spatial encoding data meeting event of current acquisition, carry out forward direction and backwards projection in conjunction with TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain.

Preferably, described method also comprises:

First data component described in each is not stored into each the first contiguous memory space, and each the first contiguous memory space is numbered according to described first preset order;

Second data component described in each is not stored into each the second contiguous memory space, and each the second contiguous memory space is numbered according to described second preset order;

3rd data component described in each is not stored into each the 3rd contiguous memory space, and each the 3rd contiguous memory space is numbered according to described 3rd preset order;

4th data component described in each is not stored into each the 4th contiguous memory space, and each the 4th contiguous memory space is numbered according to described 4th preset order;

Each spatial encoding data in described 4th data group is stored into each the 5th contiguous memory space respectively, and each the 5th contiguous memory space is numbered according to described 5th preset order;

And/or,

According to direction encoding, the first data component described in each is not stored into each the first contiguous memory space, and all directions coding related to is numbered according to described first preset order;

According to regional code, the second data component described in each is not stored into each the second contiguous memory space, and the regional coding related to is numbered according to described second preset order;

According to ring difference coding, the 3rd data component described in each is not stored into each the 3rd contiguous memory space, and each ring difference coding related to is numbered according to described 3rd preset order;

According to time-bin coding, the 4th data component described in each is not stored into each the 4th contiguous memory space, and each time-bin coding related to is numbered according to described 4th preset order;

According to axially encoding, each spatial encoding data in described 4th data group is stored into each the 5th contiguous memory space respectively, and each the axial coding related to is numbered according to described 5th preset order;

Wherein, described second contiguous memory space belongs to described first contiguous memory space, described 3rd contiguous memory space belongs to described second contiguous memory space, described 4th contiguous memory space belongs to described 3rd contiguous memory space, and described 5th contiguous memory space belongs to described 4th contiguous memory space.

Describedly obtain each spatial encoding data meeting event successively according to ranking results, comprising:

According to memory headroom numbering and/or the numbering to space encoding, meet the spatial encoding data of event according to each acquisition successively in memory headroom of number order.

The embodiment of the present invention additionally provides a kind of PET image reconstruction device, comprising:

Coding determining unit, the table schema list-mode data of PET reconstruction are used for for basis, determine that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, described spatial encoding data comprises the first coding, the second coding, the 3rd coding, the 4th coding and the 5th coding;

Ordering of events unit, for sorting all spatial encoding data according to pre-set space order;

Image reconstruction unit, for processing each spatial encoding data successively according to the ranking results of described ordering of events unit, to complete PET image reconstruction by iterative reconstruction algorithm;

Wherein,

Preferably, described device also comprises:

Direction encoding unit, for described coding determining unit according to be used for PET rebuild list-mode data, before determining that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, if each detector rings comprises M probe unit, be then divided into meeting the projecting direction of event in described fault plane plant or M kind, and encode to obtain to often kind of projecting direction individual or M direction encoding; Regional code unit, for being divided into when projecting direction kind time, the view field of the M-1 under same projection direction in described fault plane is encoded, to obtain M-1 regional code, when projecting direction is divided into M kind, by under same projection direction in described fault plane individual or individual view field encodes, to obtain individual or individual regional code;

Ring difference coding unit, if for there is P the detector rings of placing successively side by side, then, on fault plane axial direction, the Q kind detector rings difference under same projection direction encoded, to obtain Q ring difference coding, Q≤P;

Time encoding unit, for fault plane axial region being divided into the N number of time interval axially parallel with fault plane, and encoding to the N number of time interval under same projection direction, encoding to obtain N number of time-bin;

Axial coding unit, for carrying out axial coding to the Z kind axis projection region with same probe ring difference RD under same projection direction, to obtain Z axially coding, Z=P-RD;

Wherein, M, q, P, N, Z are natural number.

Preferably, described ordering of events unit, comprising:

First sequence subelement, for being divided into same first data group by all spatial encoding data that equidirectional should be had to encode, and sorts the first data group described in each according to the first preset order;

Second sequence subelement, for being divided into same second data group by described first data group to all spatial encoding data that same area should be had to encode, and sorts the second data group described in each according to the second preset order;

3rd sequence subelement, for being divided into same 3rd data group by described second data group to all spatial encoding data that identical ring difference should be had to encode, and sorts the 3rd data group described in each according to the 3rd preset order;

4th sequence subelement, for being divided into same 4th data group by described 3rd data group to all spatial encoding data that identical time-bin should be had to encode, and sorts the 4th data group described in each according to the 4th preset order;

5th sequence subelement, for sorting all spatial encoding data in described 4th data group according to the 5th preset order.

Preferably, described image reconstruction unit, comprising:

Event data obtains subelement, for obtaining each spatial encoding data meeting event successively according to ranking results;

First iterative computation subelement, if the spatial encoding data meeting event for the current spatial encoding data and upper meeting event is different, then carries out forward direction and backwards projection in conjunction with flight time TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain;

Iteration result assignment subelement, if the spatial encoding data meeting event for the current spatial encoding data and upper meeting event is identical, then meet event forward projection using upper one or backwards projection result meets event forward projection or backwards projection result as current;

Or described image reconstruction unit, comprising:

Secondary iteration computation subunit, for the spatial encoding data meeting event for current acquisition, carry out forward direction and backwards projection in conjunction with TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain.

Preferably, described device also comprises:

First space numbered cell, for the first data component described in each is not stored into each the first contiguous memory space, and is numbered according to described first preset order each the first contiguous memory space;

Second space numbered cell, for the second data component described in each is not stored into each the second contiguous memory space, and is numbered according to described second preset order each the second contiguous memory space;

3rd space numbered cell, for the 3rd data component described in each is not stored into each the 3rd contiguous memory space, and is numbered according to described 3rd preset order each the 3rd contiguous memory space;

4th space numbered cell, for the 4th data component described in each is not stored into each the 4th contiguous memory space, and is numbered according to described 4th preset order each the 4th contiguous memory space;

5th space numbered cell, for each spatial encoding data in described 4th data group is stored into each the 5th contiguous memory space respectively, and is numbered according to described 5th preset order each the 5th contiguous memory space;

And/or,

First coding numbered cell, for the first data component described in each not being stored into each the first contiguous memory space according to direction encoding, and is numbered according to described first preset order all directions coding related to;

Second coding numbered cell, for the second data component described in each not being stored into each the second contiguous memory space according to regional code, and is numbered according to described second preset order the regional coding related to;

3rd coding numbered cell, for the 3rd data component described in each not being stored into each the 3rd contiguous memory space according to ring difference coding, and is numbered according to described 3rd preset order each ring difference coding related to;

4th coding numbered cell, for the 4th data component described in each not being stored into each the 4th contiguous memory space according to time-bin coding, and is numbered according to described 4th preset order each time-bin coding related to;

5th coding numbered cell, for each spatial encoding data in described 4th data group being stored into each the 5th contiguous memory space respectively according to axially encoding, and is numbered according to described 5th preset order each the axial coding related to;

Wherein, described second contiguous memory space belongs to described first contiguous memory space, described 3rd contiguous memory space belongs to described second contiguous memory space, described 4th contiguous memory space belongs to described 3rd contiguous memory space, and described 5th contiguous memory space belongs to described 4th contiguous memory space;

Described event data obtains subelement, specifically for according to memory headroom numbering and/or the numbering to space encoding, meets the spatial encoding data of event according to each acquisition successively in memory headroom of number order.

The PET image reconstruction method that the embodiment of the present invention provides and device, by determining that in list-mode data, each meets spatial encoding data corresponding to event data, and all spatial encoding data meeting event are sorted, ensure that the complete ordering property in the space of list-mode data, utilize the orderly list-mode spatial encoding data of complete space, directly can carry out space orientation to meeting event data, thus only need calculate non-zero, not only save computational resource, also accelerate reconstruction speed.

In addition, this programme can judge currently to meet event space position and upper whether meet event space position identical according to described spatial encoding data, if identical, direct a upper result of calculation assignment is currently met event, thus significantly reduce the calculated amount that double counting same position meets event, avoid the double counting to identical data, make when the approximation method such as do not use any data down-sampled, just can realize the image reconstruction fast and accurately based on list-mode data, even if meet event number to be multiplied, also only a small amount of reconstruction time can be increased.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is embodiment of the present invention List-mode data space coding schematic diagram;

Fig. 2 is embodiment of the present invention projecting direction and view field first schematic diagram;

Fig. 3 is embodiment of the present invention projecting direction and view field second schematic diagram;

Fig. 4 is the schematic flow sheet of embodiment of the present invention PET image reconstruction method;

Fig. 5 is that embodiment of the present invention data group divides dendrogram;

Fig. 6 is the realization flow figure of embodiment of the present invention iterative reconstruction algorithm;

Fig. 7 is the structural representation of embodiment of the present invention PET image reconstruction device.

Embodiment

For making the object of the embodiment of the present invention, technical scheme and advantage clearly, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Under the impregnable prerequisite of guarantee PET image quality, the embodiment of the present invention proposes a kind of PET image reconstruction method of the list-mode data orderly based on complete space, realize three-dimensional iterative reconstruction fast, it is starting point that the method calculates two principal elements from the non-sequential data access and non-duplicate that improve reconstruction speed, by carrying out order space coding to list-mode data to realize non-sequential data access and non-duplicate calculating, and the iterative reconstruction approach such as combination such as OSEM, do not using the process of any data lack sampling with while ensureing computational accuracy, realize the fast image reconstruction based on list-mode data.

Be specifically introduced with regard to the embodiment of the present invention below.

In order to obtain the list-mode data of spacial ordering, need the spatial information of list-mode data and temporal information to be converted to spatial encoding data completely, spatial information and time difference information namely by meeting event in calculating list-mode data obtain a group index coding that can represent and meet event data complete information.This process refers to, determine that each meets the space encoding of event respectively, namely event is met for a certain, receive the time difference information of two annihilation photons according to the detector position information and detector that receive annihilation photon in list-mode data, calculate this meet projecting direction belonging to event, meet event in the downward view field position of the party, meet ring belonging to event poor, meet (time-bin) position of time interval belonging to event and meet the axial location of event in affiliated time-bin position distinguish five corresponding index coding parameters.

In order to obtain each space encoding information meeting event (i.e. above-mentioned five index coding parameters), before this, need the various coding situation of predefine, List-mode data space coding schematic diagram shown in Figure 1, defines five class index codings below in the following order successively:

1, direction encoding

In embodiments of the present invention, if each detector rings comprises M probe unit, be then divided into meeting the projecting direction of event in fault plane (detector rings interior zone) plant or M kind, and encode to obtain to often kind of projecting direction or a M kind direction encoding; Wherein, m is natural number.

Particularly, see Fig. 1 (a), outside annular region is used for representing pet detector ring, the view field (such as shadow region) of the Regional Representative between two rays in detector rings.If each pet detector ring contains M probe unit, so use (wherein, ) represent projection angle, be heterodromous because each meets annihilation photon paired in event, so with 0 to 180 degree for projection angle range, can get optional position is here 0 degree of projection angle.Due to each projection angle just corresponding projecting direction, projecting direction can be divided into plant or M kind, M is generally even number, when projecting direction adds up to individual, can arrange according to projecting direction this individual direction encoding, when projecting direction adds up to M, can arrange φ=0 according to projecting direction, this M of 1,2..., M-1 direction encoding.It should be noted that, all view fields under all projecting directions and certain projecting direction just schematically, do not put on display by Fig. 1 (a).

2, regional code

In embodiments of the present invention, when projecting direction is divided into kind time, the view field of the M-1 under same projection direction in described fault plane is encoded, to obtain M-1 regional code, when projecting direction is divided into M kind, by under same projection direction in described fault plane individual or individual view field encodes, to obtain individual or individual regional code; Wherein, M is natural number.

Particularly, see Fig. 1 (b), in fault plane, there is the view field under one group of same projection direction, represent the regional code of a certain view field under a certain projecting direction with Bin (Bin ∈ N), when projecting direction is divided into kind time, the Bin=0 under same projecting direction can be obtained, this M-1 of 1,2, L, M-2 regional code, when projecting direction is divided into M kind, can obtain under same projecting direction this individual or this individual regional code.It should be noted that, all view fields under certain projecting direction just schematically, do not put on display by Fig. 1 (b).

In order to the dividing mode of above-mentioned direction encoding and regional code is described more easily, illustrate below:

Projecting direction shown in Figure 2 and the projecting direction shown in view field first schematic diagram and Fig. 3 and view field second schematic diagram, here the probe unit number M=8 of detector rings is supposed, each probe unit is according to 0,1 ... the order of 7 is numbered, the direction of arrow represents projecting direction, the region between dotted line and the Regional Representative view field between dotted line and probe unit.

In Fig. 2, such as probe unit 0, think that probe unit 0 is identical to the projecting direction between probe unit 2 and probe unit 0 to probe unit 3, get the projecting direction between probe unit 0 to probe unit 3 herein, in this manner, make region between every two probe units under often kind of projecting direction as a view field, under this projecting direction dividing mode, co-exist in plant projecting direction, there is M-1 kind view field under often kind of projecting direction, first figure in such as Fig. 2, M-1 view field under this projecting direction is respectively 12 regions, 03 region, 74 regions, 65 regions, 13 regions, 04 region and 75 regions.

In Fig. 3, such as probe unit 0, think that probe unit 0 is two kinds of projecting directions to the projecting direction between probe unit 2 and probe unit 0 to probe unit 3, in this manner, under some projecting directions, make region between every two probe units as a view field, region under some projecting directions between existence three probe units is as a view field, under this projecting direction dividing mode, for adjacent two kinds of projecting directions, its view field's number corresponding is respectively respectively with kind.

3, ring difference coding

In embodiments of the present invention, if there is P the detector rings of placing successively side by side, then, on fault plane axial direction, the Q kind detector rings difference under same projection direction is encoded, to obtain Q ring difference coding; Wherein, Q≤P, Q, P are natural number.

Particularly, described detector rings difference RD is the difference going through number of rings and 1, wherein, described number of rings of going through is the detector rings quantity that the view field on fault plane axial direction goes through, particularly, described detector rings difference obtains by calculating the difference detecting two the probe unit place detector rings codings meeting event.For convenience of understanding, see Fig. 1 (c), for the pet detector (P=8 in figure comprising P detector rings, corresponding detector rings 0,1 respectively ... 7), each ring difference coding is defined as RingDiff=0,1 respectively, 2, L, P-1 (RingDiff ∈ N), corresponding respectively to detector rings difference RD is 0,1,2 ... the situation of P-1.Such as, if certain view field meeting event sees 00 region (solid line bar-shaped zone) being positioned at detector rings 0 in the axial direction, the detector rings quantity that then this view field goes through is 1, therefore its detector rings difference is 0, thus this meets ring difference coding RingDiff=0 corresponding to event, same, view field is positioned at 11 regions, 22 regions of detector rings ... 77 regions meet event, the detector rings difference of its correspondence is also 0, and then the ring difference coding RingDiff of correspondence is also 0; Again such as, if certain view field meeting event sees 07 region (dashed region) being positioned at detector rings in the axial direction, the detector rings quantity that then this view field goes through is 8, therefore its detector rings difference is 8-1=7, thus this meets ring difference coding RingDiff=7 corresponding to event.

It should be noted that, in actual use, can choose Q kind from this P kind detector rings difference, and encode to it, namely can not encode to the detector rings difference of all kinds, the detector rings difference of a selected part kind carries out encoding.

4, time-bin coding

In embodiments of the present invention, fault plane axial region is divided into the N number of time interval axially parallel with fault plane, and the N number of time interval under same projection direction is encoded, encode to obtain N number of time-bin; Wherein, N is natural number.

Particularly, event is met for each, PET system can record the mistiming that two annihilation photons arrive two detector cells in opposite direction, see Fig. 1 (d), according to the minimum interval t of mistiming described in PET system log (SYSLOG), fault plane axial region (region in figure between detector rings) can be divided into several take t as interlude interval (time-bin), and so just can obtain is N number of time interval (time-bin) at interval with t in a certain projecting direction view field.If the time-bin quantity N=n+1 divided, if then represent the time-bin coding meeting event with Timebin (Timebin ∈ N), then Timebin=0,1,2L, n.Time-bin position affiliated when this annihilation event (meeting event) occurs just can be calculated by the mistiming utilizing the annihilation photon recorded in list-mode data to arrive detector.

It should be noted that, above-mentioned N number of time interval (time-bin) divides according to minimum interval t, and the interval larger than minimum interval t in fact can be selected to carry out the division of time-bin, play the effect of certain speed-up computation like this, but reconstructed image quality may have very slight decline.

5, axially encode

In embodiments of the present invention, axial coding is carried out to the Z kind axis projection region with same probe ring difference RD under same projection direction, to obtain Z axially coding, Z=P-RD; Wherein, Z is natural number.

Particularly, after completing Timebin space encoding, want the unique positions determining to meet event, also need to calculate and meet event position residing in one group of axially parallel view field.See Fig. 1 (d), for the pet detector comprising P detector rings, when detector rings difference RD is 0, there is view field's (8 solid line bar-shaped zones namely in Fig. 1 (c)) that Z=P kind is parallel to each other, when detector rings difference RD is 1, there is the view field that Z=P-1 kind is parallel to each other ... when detector rings difference RD is P-1, there is Z=1 kind view field.Being the situation of P=8, detector rings difference RD=2 in Fig. 1 (d), there is the view field that Z=8-2=6 kind is parallel to each other in it.Represent that the view field that the Z=P-RD kind under same probe ring difference RD is parallel to each other carries out axial space coding with Z_Paral (Z_Paral ∈ N), axial coding range like this for any one group of parallel projection region is Z_Paral=0,1,2..., P-RD.

Like this, by using these five spatial index codings just the spatial information of list-mode data and temporal information can be showed completely.

See Fig. 4, be the schematic flow sheet of the PET image reconstruction method that the embodiment of the present invention provides, the method comprises the following steps:

Step 401: according to the table schema list-mode data of rebuilding for PET, determine that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, described spatial encoding data comprises the first coding, the second coding, the 3rd coding, the 4th coding and the 5th coding.

Wherein,

Before step 401, describe the definition mode of five index coding parameters, on this basis, according to each room and time information meeting event of PET system log (SYSLOG), can calculate respectively and eachly meet the space encoding information comprising these five kinds of index coding parameters corresponding to event.

In step 401, specifically determine that each meets space encoding corresponding to event data in the following manner, be specifically described below in conjunction with Fig. 1 and related example:

1, according to the spatial information meeting event in described list-mode data, described in determining, meet the actual projecting direction of event in described fault plane, and meet direction encoding corresponding to event data described in determining according to described actual projecting direction.

Suppose that PET system comprises 8 detector rings, and each detector rings comprises 32 probe units.

For meeting event A, this actual projecting direction meeting event A can be calculated according to list-mode data, composition graphs 1 (a), suppose that its actual projecting direction is the direction that solid arrow points to, according to the definition mode of above-mentioned direction encoding, can determine can suppose φ=6 here by the direction encoding φ that this actual projecting direction is corresponding.Like this, meeting the projecting direction of event in fault plane by calculating in list-mode data, being numbered meeting event data according to projecting direction, the meet event data identical in fault plane inner projection direction just can be made to have identical direction numbering.

2, according to the spatial information meeting event in described list-mode data, described in determining, meet the actual view field of event under described actual projecting direction, and meet regional code corresponding to event data described in determining according to described actual view field.

For meeting event A, this actual view field meeting event A can be calculated according to list-mode data, suppose that actual view field is the shaded bar frame on the right in Fig. 1 (b), according to the definition mode of above-mentioned zone coding, can determine to suppose Bin=12 here by the regional code Bin that this actual view field is corresponding.Like this, meet event data to what there is equidirectional numbering φ, its regional code Bin in fault plane can be determined respectively.

3, according to the spatial information meeting event in described list-mode data, meet the actual detector ring of event under described actual projecting direction described in determining poor, and meet ring difference coding corresponding to event data described in determining according to described actual detector ring difference.

For meeting event A, this actual detector ring meeting event A can be calculated poor according to list-mode data, composition graphs 1 (c), if detector number of rings P=8, meet event A detector rings difference RD=2, according to the definition mode of above-mentioned ring difference coding, the ring difference coding RingDiff=2 meeting event A can be determined.Like this, event data can be met to what there is equidirectional numbering respectively, determine its ring in PET axis difference numbering according to spatial order.

4, two annihilation photons meeting event described in described list-mode data are utilized to arrive the mistiming of different probe unit respectively, meet the real time affiliated when event occurs described in determining interval, and meet time-bin coding corresponding to event data described in determining according to described real time interval.

Composition graphs 1 (d), supposing to meet in event A the mistiming that two annihilation photons arrive different probe unit is respectively 0, then meeting real time interval affiliated when event occurs is middle time interval, according to the definition mode that above-mentioned time-bin encodes, supposes that time-bin coding range is Timebin=0,1,2L, n=0,1,2 ... 6, then the interval corresponding time-bin of interlude is encoded to Timebin=3.Like this, just same projection direction in fault plane will be in list-mode data and the time difference information meeting event data with same probe ring difference is converted to time-bin coded message.

5, according to the spatial information meeting event in described list-mode data, meet the actual axle of event in described real time interval described in determining to view field, and described in determining to view field according to described actual axle, meet axis coding corresponding to event data.

Composition graphs 1 (d), for meeting event A, can determine to meet the actual axle of event A to view field in 6 kinds of corresponding when ring difference encodes RingDiff=2 further axis projection regions be parallel to each other according to list-mode data, namely determine to meet event A in the time interval corresponding to Timebin=3 in particular location, according to the definition mode of above-mentioned axially coding, suppose that the actual axle determined is the 2nd article (dash area) in 6 kinds of view fields to view field, then meet the axis coding Z_Paral=1 of event A.

Visible, utilization orientation coding φ=6, regional code Bin=12, ring difference coding RingDiff=2, time-bin are encoded to these five spatial index codings of Timebin=3, axially coding Z_Paral=1 and just the spatial information meeting event data and temporal information that meet event A can be showed completely.

Step 402: all spatial encoding data are sorted according to pre-set space order.

When after the spatial index coding that step 401 completes list-mode data, also need list-mode spatial encoding data to carry out order arrangement according to space distribution.First need index coding the putting in order between φ, Bin, RingDiff, Timebin and Z_Paral determining to meet event, this puts in order is not arbitrary, because different arrangement modes may cause the temporal greatest differences of PET image reconstruction.By analyzing and the checking of previous work, think that the space encoding indexed sequential being more conducive to raising reconstruction speed is φ, Bin, RingDiff, Timebin and Z_Paral.

When after the order confirming five entry index codings, first, all event space coded datas that meets are divided extremely according to direction encoding φ in (or M) individual group, and by this (or M) individual group sorts according to a definite sequence, wherein often organize spatial encoding data and all there is identical projecting direction, namely in each group data to meet event all identical in fault plane inner projection direction, and often organize and meet event all by the view field position under certain direction in data, meet ring belonging to event poor, each coding meeting time-bin position belonging to event and meet event axial location residing in time-bin corresponding represents, like this, often organizing in data, only needing encodes according to other four entry index except direction encoding just can determine the wherein a certain relevant information meeting event.Then, respectively by the spatial encoding data in the grouping of each direction according to the regional code Bin of view field divide to M-1 ( or ) in individual group, and by this M-1 ( or ) individual group sort according to a definite sequence.Subsequently, respectively the spatial encoding data in the grouping of each view field is divided in P group according to ring difference coding RingDiff, and this P group is sorted according to a definite sequence.Subsequently, respectively the spatial encoding data in each ring differential set is divided in N number of group according to time-bin coding Timebin, and this N number of group is sorted according to a definite sequence.Finally, respectively each spatial encoding data with certain Z_Paral that axially encodes in each time-bin grouping is sorted according to a definite sequence.Like this, the conversion from the list-mode data of time sequencing arrangement to complete space ordered data collection is finally achieved.

In order to understand the sortord of each spatial encoding data more easily, dividing dendrogram below in conjunction with the data group shown in Fig. 5 and being described:

1, be divided into same first data group by all spatial encoding data that equidirectional should be had to encode, and the first data group described in each is sorted according to the first preset order.

As previously mentioned, if direction encoding comprises kind, then all spatial encoding data maximum (may not comprise certain projecting direction here) can be divided into individual first data group, is respectively the first data group 1, first data group 2 ..., the first data group and each first data group comprises all spatial encoding data (as Fig. 5) with same projection direction.These the first data groups are sorted according to the first preset order such as direction encoding (from big to small or from small to large), supposes to be from left to right final ranking results here.

In addition, the first data component described in each can be stored into each the first contiguous memory space by the embodiment of the present invention, and is numbered according to described first preset order each the first contiguous memory space; And/or, according to direction encoding, the first data component described in each is not stored into each the first contiguous memory space, and all directions coding related to is numbered according to described first preset order.Wherein, can be mutual continuous print memory headroom between each the first contiguous memory space also can be mutual discontinuous memory headroom.

Be understandable that, at the spatial encoding data that fault plane inner projection direction is identical, there is identical direction numbering, these spatial encoding data with equidirectional coding are divided in the first corresponding data group, by different first data group being stored into the diverse location in Computer Storage space, according to projecting direction, serial number is carried out to the memory headroom storing data again, the consistent spatial encoding data in fault plane inner projection direction is made to be in one piece of continuous print Computer Storage space, corresponding memory headroom numbering can be found like this by specific projection direction a certain in fault plane, and then find all spatial encoding data under this specific projection direction, certainly, also serial number can be carried out according to projecting direction to all directions coding related to, the numbering of corresponding direction encoding can be found like this by specific projection direction a certain in fault plane, and then find all spatial encoding data under this specific projection direction.

2, by described first data group, same second data group is divided into all spatial encoding data that same area should be had to encode, and the second data group described in each is sorted according to the second preset order.

As previously mentioned, if the regional code of the view field under same projecting direction comprises kind, then for the first data group 1, all spatial encoding data in the first data group 1 maximum (may not comprise certain view field here) can be divided into individual second data group, is respectively the second data group 11, second data group 12 ..., the second data group and each second data group comprises the spatial encoding data (as Fig. 5) with same projection region under same projection direction.These the second data groups are sorted according to the second preset order such as regional code (from big to small or from small to large).Similarly, other the first data group is also divided into groups in the manner described above and sorts, and does not repeat them here.

In addition, the second data component described in each can be stored into each the second contiguous memory space by the embodiment of the present invention, and is numbered according to described second preset order each the second contiguous memory space; And/or, according to regional code, the second data component described in each is not stored into each the second contiguous memory space, and the regional coding related to is numbered according to described second preset order; Wherein, described second contiguous memory space belongs to described first contiguous memory space.

Be understandable that, same projecting direction lower area is numbered the same area that identical all spatial encoding data are stored into Computer Storage space, according to regional code, serial number is carried out to the memory headroom storing data again, fault plane inner region consistent spatial encoding data of encoding is made to be in one piece of continuous print Computer Storage space, corresponding memory headroom numbering can be found by specific projection region a certain in fault plane like this, and then find all spatial encoding data under this specific projection region; Certainly, also serial number can be carried out according to fault plane inner projection region to the regional coding related to, the numbering of corresponding regional code can be found like this by a certain specific projection region, and then find all spatial encoding data under this specific projection region.

3, by described second data group, same 3rd data group is divided into all spatial encoding data that identical ring difference should be had to encode, and the 3rd data group described in each is sorted according to the 3rd preset order.

As previously mentioned, if the ring difference coding under same projecting direction comprises P kind, then for the second data group 11, all spatial encoding data in second data group 11 maximum (may not comprise certain ring here poor) can be divided into P the 3rd data group, be respectively the 3rd data group 111, the 3rd data group 112 ..., the 3rd data group 11P, and each the 3rd data group comprises the spatial encoding data (as Fig. 5) with same probe ring difference under same projection direction.These the 3rd data groups are sorted according to the 3rd preset order such as ring difference coding (from big to small or from small to large).Similarly, other the second data group is also divided into groups in the manner described above and sorts, and does not repeat them here.

In addition, the 3rd data component described in each can be stored into each the 3rd contiguous memory space by the embodiment of the present invention, and is numbered according to described 3rd preset order each the 3rd contiguous memory space; And/or, according to ring difference coding, the 3rd data component described in each is not stored into each the 3rd contiguous memory space, and each ring difference coding related to is numbered according to described 3rd preset order; Wherein, described 3rd contiguous memory space belongs to described second contiguous memory space.

Be understandable that, the identical all spatial encoding data of ring difference numbering under same projecting direction are stored into the same area in Computer Storage space, according to ring difference coding, serial number is carried out to the memory headroom storing data again, the consistent spatial encoding data of fault plane inner ring difference coding is made to be in one piece of continuous print Computer Storage space, corresponding memory headroom numbering can be found by a certain specific detector ring difference like this, and then find all spatial encoding data under this specific detector ring difference; Certainly, also can carry out serial number according to detector rings difference to each ring difference coding related to, the numbering of corresponding ring difference coding can be found like this by a certain specific detector ring difference, and then find all spatial encoding data under this specific detector ring difference.

4, by described 3rd data group, same 4th data group is divided into all spatial encoding data that identical time-bin should be had to encode, and the 4th data group described in each is sorted according to the 4th preset order.

As previously mentioned, if the time-bin coding under same projecting direction comprises N kind, then for the 3rd data group 111, all spatial encoding data in 3rd data group 111 maximum (may not comprise the initial time-bin position that certain meets event here) can be divided into N number of 4th data group, be respectively the 4th data group 1111, the 4th data group 1112 ..., the 4th data group 111N, and each the 4th data group comprises the spatial encoding data (as Fig. 5) with identical initial time-bin position under same projection direction.These the 4th data groups are sorted according to the 4th preset order such as time-bin coding (from big to small or from small to large).Similarly, other the 3rd data group is also divided into groups in the manner described above and sorts, and does not repeat them here.

In addition, the 4th data component described in each can be stored into each the 4th contiguous memory space by the embodiment of the present invention, and is numbered according to described 4th preset order each the 4th contiguous memory space; And/or, according to time-bin coding, the 4th data component described in each is not stored into each the 4th contiguous memory space, and each time-bin coding related to is numbered according to described 4th preset order; Wherein, described 4th contiguous memory space belongs to described 3rd contiguous memory space.

Be understandable that, identical all spatial encoding data of being encoded by time-bin under same projecting direction are stored into the same area in Computer Storage space, according to time-bin coding, serial number is carried out to the memory headroom storing data again, time-bin consistent spatial encoding data of encoding is made to be in one piece of continuous print Computer Storage space, corresponding memory headroom numbering can be found by the specific initial time-bin position meeting event like this, and then find all spatial encoding data under this specific initial time-bin position; Certainly, also serial number can be carried out according to described initial time-bin position to each time-bin coding related to, the numbering of corresponding time-bin coding can be found like this by a certain specific initial time-bin position, and then find all spatial encoding data under this specific initial time-bin position.

5, all spatial encoding data in described 4th data group are sorted according to the 5th preset order.

Each the 4th data group comprise identical ring difference coding and identical time-bin encodes lower one or more spatial encoding data, axis coding corresponding to these spatial encoding data may all difference, also may be partly or entirely identical.If axis coding corresponding to these spatial encoding data is all different, then can by these spatial encoding data according to the 5th preset order for example axially coding (from big to small or from small to large) sort, if the axial coded portion that these spatial encoding data are corresponding is identical and part is different, the spatial encoding data then these with axially different coding according to the 5th preset order for example axially coding (from big to small or from small to large) sort, and the spatial encoding data with same axial coding is sorted according to data obtaining time (or other modes), see Fig. 5, such as, spatial encoding data 11111 to 1111Z arranges from big to small according to axially encoding, wherein, data 11111 with 11112 axis encode identical, due to PET system first get data 11111 after get data 11112, therefore data 1111 sort formerly, data 11112 sort rear, if the axis coding that these spatial encoding data are corresponding is all identical, then the spatial encoding data these with same axial coding sorts according to data obtaining time (or other modes).

In addition, each spatial encoding data in described 4th data group can be stored into each the 5th contiguous memory space by the embodiment of the present invention respectively, and is numbered according to described 5th preset order each the 5th contiguous memory space; And/or, according to axially encoding, each spatial encoding data in described 4th data group is stored into each the 5th contiguous memory space respectively, and each the axial coding related to is numbered according to described 5th preset order; Wherein, described 5th contiguous memory space belongs to described 4th contiguous memory space, and described 5th contiguous memory space is made up of one or more internal storage location.

Based on above-mentioned sequence, final data sorting result is 11111,11112 ... 1111Z ..., i.e. last row ranking results from left to right in Fig. 5.

Step 403: process the spatial encoding data that each meets event successively according to ranking results, to complete PET image reconstruction by iterative reconstruction algorithm.

For the iterative reconstruction algorithm that step 403 is mentioned, as shown in Figure 6, what the figure shows the iterative reconstruction algorithms such as OSEM realizes basic procedure to specific implementation.First forward projection calculating is carried out to the initial estimation image of setting, the theoretical projection value obtained with it compares with actual measurement projection value, thus obtain projection correction's factor, projection correction's factor obtains image correction factor after back projection calculates, after being acted on initial estimation image, just achieve an iterative computation, have passed through successive ignition, estimated image is restrained gradually, until it is corrected for meet necessarily required reconstruction image.

Due in the iterative approximation of existing sinogram data for projection, need to travel through all possible projection to complete forward direction and backwards projection calculating according to certain spatial order, and in this process, be mostly that the neutral element in data space is being calculated, waste computational resource; And existing conventional list-mode data re-establishing method can only calculate nonzero element, but the unordered feature of its data space result in the slow of reconstruction speed.And use complete space ordered data collection in the embodiment of the present invention to carry out image reconstruction, then eliminate the defect of these two aspects.

In embodiments of the present invention, the one in following two kinds of modes specifically can be selected to realize step 403:

Mode one: obtain each spatial encoding data meeting event successively according to ranking results; Judge that whether the spatial encoding data that the current spatial encoding data and upper meeting event meets event is different; The spatial encoding data that the spatial encoding data and upper meeting event if current meets event is different, then carry out forward direction and backwards projection in conjunction with flight time TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain; The spatial encoding data that the spatial encoding data and upper meeting event if current meets event is identical, then meet event forward projection using upper one or backwards projection result meets event forward projection or backwards projection result as current.

Mode two: obtain each spatial encoding data meeting event successively according to ranking results; For the spatial encoding data meeting event of current acquisition, carry out forward direction and backwards projection in conjunction with TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain.

Be understandable that, for mode one, when the quantity of spatial encoding data is the situation of low data bulk and intermediate data amount, because the ratio meeting the repetition of event space coding is very little, so judge that continuous two meet the whether identical and projection of event code and calculate this part operation, it does not have the castering action of computing velocity or not quite, only when the data volume of spatial encoding data is larger, the ratio repeated due to space encoding increases, gradually so accelerating effect could embody gradually.For mode two, whether not judging continuous two, to meet event code identical, event space coded data is met for each all need to carry out projection computing one by one, when the quantity of spatial encoding data is the situation of low data bulk and intermediate data amount, also can selection mode two, its treatment effect gap compared with mode one is little.

In above-mentioned two kinds of modes, in order to obtain each spatial encoding data successively according to ranking results, specifically according to memory headroom numbering and/or the numbering to space encoding, the spatial encoding data of event can be met according to each acquisition successively in memory headroom of number order.Namely, both can number according to memory headroom the spatial encoding data searched in internal memory, also can search the spatial encoding data in internal memory according to the numbering of each coding in space encoding, the spatial encoding data in internal memory can also be searched in conjunction with the numbering of each coding in memory headroom numbering and space encoding.Such as, the mode of searching is numbered in conjunction with two classes for the third, in actual applications, specifically can be positioned according to memory headroom number order the preceding first data group with same projection direction being stored in the first contiguous memory space that sorts, the spatial encoding data of locating one by one in order in this first data group is numbered successively again according to regional code numbering, ring poor coding numbering, time-bin coding numbering and axial coding, certainly also have other combination, this is no longer going to repeat them.

Illustrate:

See Fig. 5, according to the ranking results meeting event space coded data, first obtain and meet event space coded data 11111, carry out forward direction and backwards projection in conjunction with TOF information and data 11111 to calculate and calculate to complete this, then obtain and meet event space coded data 11112, and whether compare data 11112 identical with the space encoding information of data 11111, if identical, then direct using the result of calculation of the result of calculation of data 11111 as data 11112, if different, then on the basis of last computation result, carry out forward direction and backwards projection in conjunction with TOF information and data 11112 to calculate and calculate to complete this, the like, obtain again and meet event space coded data 11113, and do above-mentioned process equally, until complete each iterative computation meeting event space coded data.

Visible, the embodiment of the present invention calculates based on the forward projection of the orderly list-mode data of complete space and backwards projection, as compared to based on the reconstruction mode of sinogram data for projection with conventional list-mode data, difference is: the first, substitutes original list-mode completely meet event data with spatial encoding data; The second, meeting event space coded data and be made up of this five entry index of φ, Bin, RingDiff, Timebin, Z_Paral coding of spatial order, directly can carry out space orientation to meeting event data; 3rd, when process one meet event after, just continue the process next one and meet event, and carry out concrete calculating the need of meeting event to this, can judge by the spatial ordering of data set, namely, judge that next meets event and whether current to meet event space position (corresponding spatial encoding data) identical, if identical, then only the current result of calculation assignment meeting event need be met event to next, thus avoid unnecessary double counting.The advantage of this operation is, improves the speed of rebuilding and calculating, and simultaneously when data volume significantly increases, reconstruction time remains unchanged substantially.

The PET image reconstruction method that the embodiment of the present invention provides, by determining that in list-mode data, each meets spatial encoding data corresponding to event data, and all spatial encoding data are sorted, ensure that the complete ordering property in the space of list-mode data, utilize the spatial encoding data of the orderly list-mode of complete space, directly can carry out space orientation to meeting event data, thus only need calculate non-zero, not only save computational resource, also accelerate reconstruction speed.

In addition, in order to contrast the difference of method for reconstructing in reconstruction speed that tradition proposes based on the list-mode reconstruction algorithm of spacial ordering subset and the embodiment of the present invention based on the list-mode reconstruction algorithm of time order subset, tradition, be 1 × 10 to meeting event count respectively ⁷individual, 4 × 10 ⁷individual and 7 × 10 ⁷individual list-mode data set carries out reconstruction contrast.Wherein, three kinds of methods all in conjunction with the OSEM algorithm of 22 data subsets, and carry out TOF reconstruction to same water mould scan-data, and after an iterative computation, obtaining resolution is the image of 256 × 256 × 65, and the reconstruction time of each method for reconstructing is as shown in the table:

Use different pieces of information amount three kinds of TOF reconstruction algorithm reconstruction times contrast (unit: second)

(Core i7-3770 tetra-thread, 16GB RAM)

Visible, compared with existing method for reconstructing, the reconstruction speed of embodiment of the present invention method for reconstructing is apparently higher than conventional images method for reconstructing.

See Fig. 7, the embodiment of the present invention additionally provides the structural representation of PET image reconstruction device, and this device 700 comprises:

Coding determining unit 701, the table schema list-mode data of PET reconstruction are used for for basis, determine that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, described spatial encoding data comprises the first coding, the second coding, the 3rd coding, the 4th coding and the 5th coding;

Ordering of events unit 702, for sorting all spatial encoding data according to pre-set space order;

Image reconstruction unit 703, meets event space coded data to each successively for the ranking results according to described ordering of events unit 702 and processes, to complete PET image reconstruction by iterative reconstruction algorithm;

Wherein,

Further, described device 700 also comprises:

Direction encoding unit, for in described coding determining unit 701 according to the list-mode data of rebuilding for PET, before determining that in described list-mode data, each meets space encoding corresponding to event data respectively, if each detector rings comprises M probe unit, be then divided into meeting the projecting direction of event in described fault plane plant or M kind, and encode to obtain to often kind of projecting direction or M direction encoding;

Regional code unit, for being divided into when projecting direction kind time, the view field of the M-1 under same projection direction in described fault plane is encoded, to obtain M-1 regional code, when projecting direction is divided into M kind, by under same projection direction in described fault plane individual or individual view field encodes, to obtain individual or individual regional code;

Ring difference coding unit, if for there is Q the detector rings of placing successively side by side, then, on fault plane axial direction, the Q kind detector rings difference under same projection direction encoded, to obtain P ring difference coding, Q≤P;

Wherein, M, q, P, N, Z are natural number.

Wherein, described ordering of events unit 702, comprising:

Wherein, described image reconstruction unit 703, comprising:

Or described image reconstruction unit, comprising:

Further, described device 700 also comprises:

And/or,

Described event data obtains subelement, specifically for according to memory headroom numbering and/or the numbering to described space encoding, meets the spatial encoding data of event according to each acquisition successively in memory headroom of number order.

The PET image reconstruction device that the embodiment of the present invention provides, by determining that in list-mode data, each meets spatial encoding data corresponding to event data, all spatial encoding data meeting event are sorted, ensure that the complete ordering property in the space of list-mode data, utilize the orderly list-mode spatial encoding data of complete space, directly can carry out space orientation to meeting event data, thus only need calculate non-zero, not only save computational resource, also accelerate reconstruction speed.

As seen through the above description of the embodiments, those skilled in the art can be well understood to the mode that all or part of step in above-described embodiment method can add required general hardware platform by software and realizes.Based on such understanding, technical scheme of the present invention can embody with the form of software product the part that prior art contributes in essence in other words, this computer software product can be stored in storage medium, as ROM/RAM, magnetic disc, CD etc., comprising some instructions in order to make a computer equipment (can be personal computer, server, or the network communication equipments such as such as media gateway, etc.) perform the method described in some part of each embodiment of the present invention or embodiment.

It should be noted that, for device disclosed in embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part illustrates see method part.

Also it should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operational zone, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.

To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims

1. a PET image reconstruction method, is characterized in that, comprising:

All spatial encoding data are sorted according to pre-set space order;

Wherein,

2. method according to claim 1, is characterized in that, is used for the list-mode data of PET reconstruction, before determining that in described list-mode data, each meets spatial encoding data corresponding to event data respectively, also comprises in described basis:

Wherein, M, q, P, N, Z are natural number.

3. method according to claim 1, is characterized in that, is describedly sorted according to pre-set space order by all spatial encoding data, comprising:

All spatial encoding data in described 4th data group are sorted according to the 5th preset order.

4. method according to claim 3, is characterized in that, describedly processes each spatial encoding data successively according to ranking results, comprising:

Or,

Each spatial encoding data meeting event is obtained successively according to ranking results; For the spatial encoding data meeting event of current acquisition, carry out forward direction and backwards projection in conjunction with TOF information and the current spatial encoding data meeting event and calculate and currently meet event forward projection and backwards projection result to obtain.

5. method according to claim 4, is characterized in that, described method also comprises:

And/or,

6. a PET image reconstruction device, is characterized in that, comprising:

Wherein,

7. device according to claim 6, is characterized in that, described device also comprises:

Wherein, M, q, P, N, Z are natural number.

8. device according to claim 6, is characterized in that, described ordering of events unit, comprising:

9. device according to claim 8, is characterized in that,

Described image reconstruction unit, comprising:

Or described image reconstruction unit, comprising:

10. device according to claim 9, is characterized in that, described device also comprises:

And/or,