CN102670232B

CN102670232B - Positron emission computed tomography device, and method executed through the same

Info

Publication number: CN102670232B
Application number: CN201210061629.8A
Authority: CN
Inventors: K·C·布尔
Original assignee: Toshiba Corp; Toshiba Medical Systems Corp
Current assignee: Canon Medical Systems Corp
Priority date: 2011-03-11
Filing date: 2012-03-09
Publication date: 2015-01-28
Anticipated expiration: 2032-03-09
Also published as: CN102670232A

Abstract

Provided are a positron emission computed tomography device, and a method executed through the positron emission computed tomography device. The positron emission computed tomography device can raise energy resolution. The positron emission computed tomography device of an embodiment comprises flasher arrays, optical sensors, a determining part, a storing part, and an exporting part; wherein, the determining part is used for determining a detection position of an interactive event between a gama ray and flashers by using units of divided areas of which the number is greater than the number of the flashers according to signal values output from one or more optical sensors; the storing part is used for exporting a total signal value, and correlatively storing the total signal value and the detection position in the storing part; and the exporting part is used for exporting a corrected value of a corrected energy value for the unit of the each area according to the total signal value and a specified energy value correlatively stored in the storing part with the detection position.

Description

Positron emission tomography device and the method performed by it

The application advocates the priority of the Japanese patent application No. 2012-029889 of the U.S. Patent Application No. application on February 14th, 13/045,610 and 2012 applied on March 11st, 2011, and quotes the full content of above-mentioned patent application in this application.

Technical field

The method that embodiment is related to Positron emission tomography device and performed by Positron emission tomography device.

Background technology

In medical imaging field, gamma-ray detector, particularly Positron emission tomography device, that is, the utilization of PET (Positron Emission Tomography) device increases.Based in the PET imaging of PET device, radiopharmaceuticals, by injecting, sucking or food intake, is taken into the subject of image conversion.After throwing in radiopharmaceuticals, according to physics and the biomolecule characteristic of medicament, medicament accumulates in the specific part in subject.The spatial distribution of the reality of medicament, the concentration of medicament accumulation region and be dynamically the factor clinically with importance from what render to final process of discharging.In this process, be attached to positron emitter on radiopharmaceutical agent according to the isotopic physical property such as half-life or branching ratio positron radiation.

Radionuclide positron radiation.When being collided by the positron that radiates and electronics, there is mutual annihilation event, positron and electron annihilation.In most cases, two gamma-rays (511keV) of radiating to roughly 180 degree rightabouts are produced by mutual annihilation event.

PET device can by detecting two gamma-rays detected roughly simultaneously, and detect between position at these, draws straight line, i.e. LOR (Line-of-response: line of response), thus with high probability, derives the position of roughly mutually burying in oblivion.By accumulating a large amount of this LOR, and perform tomography reconstruction process, thus original distribution can be estimated.Except the positional information of two annihilation event, when can also utilize correct detection timing information (within hundreds of psec), the information relevant to the estimated position of the annihilation event along LOR can be increased further by calculating TOF (time-of-flight: flight time).The boundary of the temporal resolution had by PET device, determines the precision of the location along this LOR.In addition, by the boundary during position that determines original annihilation event, the final spatial resolution of PET device can be determined.On the other hand, isotopic intrinsic characteristic (such as, positron energy) also becomes the major reason of the spatial resolution of decision (due to until there is two ranges burying in oblivion gamma-ray positron or the factor that two are buried in oblivion to the angle between gamma-rays and have an impact) PET device.

Prior art document

Non-patent literature 1:W.W.Moses work, " Time of Flight in PET Revisited ", IEEE Transactions on Nuclear Science, Vol.50, No.5, pp.1325-1330

Summary of the invention

(inventing the problem that will solve)

The problem to be solved in the present invention is, provides a kind of Positron emission tomography device that can improve energy resolution, and by method that Positron emission tomography device performs.

(scheme used of dealing with problems)

The Positron emission tomography device that embodiment relates to possesses scintillator arrays, multiple optical sensor, determination portion, storage unit, leading-out portion.Above-mentioned scintillator arrays has multiple flasher.The passage of scintillation light that above-mentioned multiple light sensors generates the gamma-rays of above-mentioned flasher input predetermined energy value.Above-mentioned determination portion is undertaken detecting by one or more above-mentioned optical sensor and the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of the interaction event of above-mentioned gamma-rays and flasher according to the diffusion by above-mentioned passage of scintillation light.Above-mentioned storage unit derives according to the signal value exported from above-mentioned optical sensor and adds up to signal value, and the total signal value of derivation and above-mentioned detection position are stored in storage part explicitly.Above-mentioned leading-out portion is stored in total signal value in storage part and afore mentioned rules energy value explicitly according to above-mentioned detection position, the unit of each above-mentioned zone is derived to the corrected value of the energy value correcting above-mentioned interaction event.

(invention effect)

Play the effect that can improve energy resolution.

Accompanying drawing explanation

Example when Fig. 1 represents that gamma-ray detector is irradiated from various radioisotopic gamma-rays, nonlinear SiPM (Silicon Photomultiplier: silicon photomultiplier) responds.

Fig. 2 A represent from thin photoconduction link 5 × 5 three examples of the distribution of light of radiating of scintillator arrays (or scintillator arrays).In the example of three shown in Fig. 2 A, the integrated value of the intensity of light is all identical, but the spreading range of light differs widely respectively.Fig. 2 A represents according to situation insufficient in a gamma correction of identified interactional flasher.

Fig. 2 B-1 represents the example of the signal level of the approximate calculation generated in a general example in the example of three shown in Fig. 2 A.

Fig. 2 B-2 represents the example of the signal level of the approximate calculation generated in a general example in the example of three shown in Fig. 2 A.

Fig. 2 B-3 represents the example of the signal level of the approximate calculation generated in a general example in the example of three shown in Fig. 2 A.As shown in Fig. 2 B-1 ~ 3, in arbitrary situation of three examples, all provide the energy value of 511keV, but the signal level exported (signal level of output signal) is different when respective.

Fig. 3 is the figure of the structure of the PET device related to for illustration of embodiment.

Fig. 4 is the figure of the structure of central processor in the PET device that relates to for illustration of embodiment.

Fig. 5 represents and collects the reading of the scintillator arrays of the photomultiplier tube (PMR (Photomultiplier Tube)) of process and 4 parts and the general source rectangular histogram (flood histogram) that obtains according to employing optical system.

Fig. 6 represents and collects the reading of the scintillator arrays of process and location sensitive type avalanche photodide (avalanche photodiode) and the general source rectangular histogram (flood histogram) that obtains according to employing analog data.

Fig. 7 A represents the flow chart of the step of the method that the PET device related to by embodiment is performed.

Fig. 7 B represents the flow chart of the step of the method that the PET device related to by another embodiment is performed.

Fig. 8 A represent by gamma-rays to contact with scintillator arrays occur, from the typical pulse of the optical sensor of the incidence of response light.

Fig. 8 B-1 is the figure of the time shaft changing Fig. 8 A.

Fig. 8 B-2 is the figure of the information representing the energy corresponding with the pulse shown in Fig. 8 A.

Fig. 9 A represents the structure of the gamma-ray detector that embodiment relates to.Fig. 9 A represents the position relationship of scintillator arrays, photoconduction and optical sensor.

Fig. 9 B represents the structure of the gamma-ray detector that embodiment relates to.Fig. 9 A represents the position relationship of scintillator arrays, photoconduction and optical sensor.

Figure 10 A represents general source rectangular histogram.

Figure 10 B represents the flasher ID look-up table corresponding with general source rectangular histogram.

(symbol description)

100 flashers

105 scintillator arrays

130 photoconductions

135,140 optical sensors

300 flashers

305 scintillator arrays

330 photoconductions

335,340 optical sensors

Detailed description of the invention

Below, the PET device with reference to accompanying drawing, embodiment related to and being described by the method that PET device performs.

The PET device that embodiment relates to possesses the gamma-ray detector having and represent significant nonlinear optical sensor.This nonlinear degree depends on the spatial distribution of the photon beam in photosensor surface.The PET device that embodiment relates to possesses the gamma-ray detector collecting process collecting process or analogue signal that can carry out optical system to reduce the quantity of required electron channel, and provides a kind of modification method carrying out nonlinear correction.

PET device buries in oblivion gamma-ray detection event mutually by collection is multiple, and carries out image reconstruction based on this event data, thus generates the image casting medicament distribution of subject.Mutually bury in oblivion gamma-rays be by from cast the medicament of subject the positron that produces and the electronics produced near point mutually bury in oblivion, thus 2 gamma-rays of direction generation at about 180 degree.In PET device, according to the event information detected in the detecting element of gamma-ray detector roughly simultaneously, form the LOR that can carry out Nogata graphing according to geometrical property.According to this LOR, specify the data for projection as the object data rebuild or sinogram data.In addition, by LOR is directly added write view data one by one, also view data can be formed.

Thus in PET device, LOR is to provide the basic key element of the mutual annihilation location information casting medicament, relevant to this mutual annihilation location information, following additional information can be obtained.First, as everyone knows, the ability describing to have the point of PET device changes to spatiality in image reconstruction regional integration, but becomes higher at central part, little by little reduces towards periphery.PSF (Point Spread Function: point spread function) is the typical function of this characteristic of performance, in recent years, is just being incorporated in process of reconstruction.Then, PET device according to TOF, that is, can be buried in oblivion the time difference information that gamma-rays arrives detector, calculates the probability distribution of the point that mutual annihilation event occurs on LOR mutually.

Above-mentioned process (imaging process) needs multiple mutual annihilation event.In current research, typically, when determining the quantity of the mutual annihilation event needed in order to can sufficient imaging processing be carried out, although must resolve imaging example one by one, but be the inspection in the FDG (fluoro-deoxyglucose: fluorodeoxyglucose) of 100cm to typical length, need to repeat several hundred million times.Decided by the injection rate of medicament and the sensitivity of PET device and numerical ability to obtain the time needed for these event numbers.

PET imaging system, i.e. PET device, in order to detect the gamma-rays radiated from subject, use the gamma-ray detector be configured on mutually opposing position.Typically, PET device, in order to detect from the sudden gamma-rays of each angle, uses the gamma-ray detector being configured to ring-type.Thus typically, the scanner of PET device is substantially cylindrical shape to catch lonizing radiation as much as possible, is certainly necessary for isotropism.In addition, scanner also can be the shape of the part lacking annulus, now, gamma-ray detector also can be made to rotate, to catch the angle lacked.But the sensitivity of such method on the entirety of PET device produces great impact.During for drum, the probability of all gamma-rays response gamma-ray detectors that face comprises is high, if make axial size become large, then very effective to the sensitivity or performance that catch lonizing radiation.Thus optimum structure to detect all gamma-ray sphere structures.Certainly, in the application of human body, chondritic becomes very big, and very expensive.Thus in reality, the axial adjustable length drum of gamma-ray detector is the basic of the structure of the scanner of up-to-date PET device.

Scanner is made up of multiple detector module, and detector module is made up of multiple flasher.In order to make the function admirable of PET device, needing to configure flasher as much as possible, and block gamma-rays as much as possible and convert light to.PET device, in order to rebuild the distribution of radioisotopic time and space, must obtain the energy value (that is, the light quantity generated in flasher) of detected each event, position and information regularly.Most up-to-date PET scanner is all made up of thousands of other flashers.These flashers are configured in detector module, for determining the position of mutual annihilation event.Typically, flicker element has the section of about 4mm × 4mm.Also can be less size or larger size, or, not foursquare section.The length of flasher or the degree of depth determine gamma-ray prevention ability, typically, are the scopes of 10 ~ 30mm.Detector module is the main element of scanner.

Performance based on the PET imaging of PET device depend on based at a high speed and the flasher of high brightness, from gamma-rays to the conversion of light.PET device can determine the position (interactional position occurs for gamma-rays and flasher) occurring in a detector to glimmer, and match (namely to each event according to temporal information, be combined in two the detection events detected in certain time window), and calculate the position of mutual annihilation event.In order to carry out these actions, needing detector (detector and electronic equipment) very at a high speed, also needing excellent signal to noise ratio.If use high-quality electronic equipment, then signal to noise ratio is main decides according to the Poisson distribution relevant to testing process.In a word, if detect more photon, will signal to noise ratio be improved, thus improve spatial resolution and temporal resolution further.In addition, when missing passage of scintillation light in testing process, even if the improvement of the design and electronic equipment with detector can not compensate.The ratio can carrying out for the light produced in flasher the light quantity detected practically is the index being suitable for the efficiency representing design part.Therefore, whoso wants the detection limit making light to maximize, and optical sensor probably all will be made to be close with flasher as far as possible, and avoids reflection and other edge effect.If carry out such step, then gamma-ray detector is probably necessary for the detector that distance between flasher and optical sensor is short, have large scintillator arrays.

As described above, PET device is not merely enumerator.PET device, outside the existence detecting mutual annihilation event, also needs the identification of the position of carrying out mutual annihilation event.If in order to identify that each interactional position is designed the most simply, design independently optical sensor and A/D converter to each flasher approximately.In order to restrict electric power needed for the physics size of optical sensor, A/D converter and these cost, for the purpose of the port number cutting down optical sensor number and electronic equipment, usually by any device, data are collected.

Two the most general modes of tidal data recovering be optical system collect process and analogue signal collect process.Use the mode of photoconduction to be the example collecting process of optical system to make light be distributed to 4 photomultiplier tubes.By suitably recording as where light being assigned to multiple optical sensor, thus for the combination that any optical sensor responds, the position with gamma-ray interaction event can both be calculated.In addition, as the example collecting process of analogue signal, there is so-called location sensitive type avalanche photodide, location sensitive type SiPM.

Collect process or analog data is collected in the design of process in optical system, use peace lattice (anger) logic (center of gravity calculation) or statistical method to calculate relative position in the detector frame of each interaction event.At this, so-called " relative position " refers to the position of the reality of flasher and gamma-rays generation interaction event (such as, absolute position in subject) relative position, be incide the position of flasher thus " the detection position " determined by calculating gamma-rays.As relative position in order to determine the flasher of gamma ray interaction, usually, the general source histogram divion obtained as a result is become the look-up table of flasher by PET device.After having gone out interactional flasher according to the location recognition in general source rectangular histogram and look-up table, each flasher is carried out to the correction of energy value and timing.Correction as energy value also can carry out gamma correction.Usually, this correction is according to employing multiple different isotope (such as, 511 and 1275keV ²²na, 662keV's ¹³⁷cs, 356keV's ¹³³ba, 122keV's ⁵⁷co, 60keV's ²⁴¹the correction of measurement Am), carries out each flicker.In addition, as will be described later, the PET device that embodiment relates to not with the unit of flasher, and with the unit in the region being divided into the quantity more than the quantity of flasher to carry out the correction of energy value.

The example of when Fig. 1 represents that gamma-ray detector is irradiated from various radioisotopic gamma-rays, nonlinear SiPM response.Gamma-ray detector comprises LYSO (Lutetium Yttrium Oxyorthosilicate: the silicic acid lutecium yttrium) crystal of 3mm × 3mm × 10mm and has the SiPM (Hamamatsu Photonics K. K's system) of 3mm × 3mm of 3600 unit.

When detecting the gamma-rays of high-energy value (such as, PET 511keV etc.), in gamma-ray detector, gamma-rays carries out Compton (Compton) scattering by multiple flasher sometimes.Thus, gamma-rays gives energy for multiple flasher.Generally speaking, the gamma-ray of 511keV interacts with multiple flasher more than 30%.Even if when the gross energy being endowed flasher is identical, according to the difference of the quantity of interactional process or interactional flasher, sometimes also quite different to the expansion of the light of optical sensor.Such as, by when flasher being given to the energy of 511keV, with two adjacent flashers are given add up to the energy of 511keV time compared with learn, by the difference that the expansion existence of the light of optical sensor is very large.

The difference of the expansion of this light becomes problem in the gamma correction of optical sensor.This is the difference due to the spatial distribution according to detected photon, and its nonlinear degree is different.This is the so-called situation employing SiPM.SiPM and silicon photomultiplier (as the SSPM (Solid-State Photomultiplier) of solid photomultiplier tube, or being called as GAPD or MAPD) are made up of multiple independently avalanche photodide.In addition, SiPM is called as " micro unit (micro cell) ", action under Geiger (Geiger) pattern.Under Geiger mode angular position digitizer, if micro unit detects more than one photon, then SiPM electric discharge.The electric charge that interdischarge interval radiates decides according to the static capacity of micro unit and operation voltage.The electric charge radiated is not driven by the quantity of carrying out the photon discharged.Such as, according to the event by the gamma-ray interaction in flasher, if the pulse of light contacts with SiPM, then multiple micro unit discharges, and produces electric pulse.The quantity of the amplitude of this electric pulse and the micro unit of electric discharge is proportional.When the density of photon is very little, the probability contacted with identical micro unit due to multiple photon is very low, and therefore, the amplitude of electric pulse changes point-blank relative to number of photons.Because the density of photon more increases, the probability that multiple photon contacts with identical micro unit more increases, therefore, and the non-linear grow of signal.

Fig. 2 A represent from thin photoconduction be connected 5 × 5 three examples of the distribution of light of radiating of scintillator arrays.Fig. 2 A represent to the energy giving 511keV in scintillator arrays, the difference of the intensity of light by predicting in three different events.In this example embodiment, flasher in the scintillator arrays of 5 × 5 carries out being separated (namely optically, these flashers have reflecting material between separately), and to combine with thin photoconduction, and combine with the optical sensor of array-like or location sensitive type optical sensor further.The graticule of Fig. 2 A represents the border of flasher.In respective case, the intensity of the light of integration is identical.In the 1st (left end) case, all energy are endowed the flasher of central authorities, and the intensity (or photon beam) of the light of peak value is the highest.In the 2nd case, gamma-rays gives the flasher (based on Compton scattering) of central authorities by 67% of energy, the flasher near giving 33% of remaining energy.In the 3rd case (right-hand member), gamma-ray energy distributes equably between two flashers.In this case, the maximum intensity of the light of each flasher obtained as a result is minimum.If depend on the density of photon, the reading of this gamma-ray detector is made to the optical sensor of the SiPM of intensity and the exporting change used up etc., then the intensity of the light of integration is identical, but the expansion of light is different, therefore, the output of optical sensor is in the case of three shown in this different.Its result energy resolution worsens.Such as, in the example shown in Fig. 2 A, even if such as give the energy of 511keV to flasher in each case, three cases separately in by the signal level of gamma correction also difference (supposing to apply identical gamma correction in each case).This is the representative example of the mechanism that energy resolution is worsened.

Fig. 2 B represents signal level that generated by three cases shown in Fig. 2 A, approximate calculation.At this, consider two flashers as an example.According to the difference of the expansion of light and the non-linear of SiPM, even if three cases all give the energy adding up to 511keV to two flashers, in respective case, the signal level of integration is also different.

Be described in detail above-mentioned.Such as, time near the central authorities that gamma-rays incides a flasher, the effect of Compton scattering is less, and the expansion towards the light of optical sensor easily diminishes.On the other hand, such as, time near the border that gamma-rays incides a flasher, the effect of Compton scattering becomes comparatively large, and the expansion towards the light of optical sensor easily becomes large.In the former case, because the expansion of light is little, therefore, be considered to the micro unit (micro unit as the SiPM of optical sensor) of photon contact lesser amt, in the latter case, because the expansion of light is large, therefore, the micro unit of the more quantity of photon contact gear ratio is considered to.At this, when photon contacts with identical micro unit continuously, due to the restriction of its hardware, SiPM can not detect all photons sometimes.On the other hand, to be discharged by micro unit and the quantity of the amplitude of electric pulse generated and the micro unit of electric discharge is proportional.Namely, contact with the micro unit of fewer quantity when photon the former when, the probability contacted with identical micro unit continuously due to photon also uprises, therefore, SiPM can not detect that the probability of all photons also uprises, and has the tendency of signal value step-down.On the contrary, as the latter that photon contacts with the micro unit of many quantity, due to the probability step-down that photon contacts with identical micro unit continuously, therefore, SiPM can detect all photons, has the tendency that signal value uprises.Like this, which position that gamma-rays incides in a flasher can have an impact to signal value.This be the PET device that relates to due to embodiment as described below, for the signal value exported by optical sensor, with the unit of the unit fine than flasher, carry out nonlinear correction.

Embodiment disclosed in this description is with sub-pix (sub-pixel) unit or apply gamma correction (non-linearity correction) continuously.At this, so-called sub-pix unit refers to the unit in the region being divided into the quantity more than the quantity of flasher.If use optical system collects process or analog data collects process, flasher in general source rectangular histogram that then can be relevant according to the peak value corresponding to each flasher and the position of gamma-ray interaction event, the interactional supplement information between obtaining for multiple flasher.Because the position occurring in the rectangular histogram of general source to glimmer calculates according to peace lattice logic (center of gravity calculation), therefore, to the event configuration of giving energy in two flashers between the peak value corresponding with two flashers.Self-evident for a person skilled in the art, the physical location of interaction position not necessarily with single calculated in these cases is corresponding, but represents the position of the versus signal level generated by optical sensor.

In addition, if ignore the impact from noise, the correct position between the peak value of each flasher is decided according to the relative energy given in two flashers.Nonlinear variation is also according to deciding the relative energy given in two flashers.Thus, by carrying out sub-pix to general source rectangular histogram, and different gamma corrections can be applied to each subpixel regions, thus, carry out more excellent gamma correction.Or, also can be applied in the gamma correction changed continuously between the peak value of each flasher.

Fig. 3 is the figure of the structure of the PET device related to for illustration of embodiment.Self-evident for a person skilled in the art, the gamma-ray detector system shown in Fig. 3 forms a part for PET device or TOF type PET device.Omit the additional explanation for PET device and TOF type PET device for simplicity.In addition, for the explanation of TOF type PET device in non-patent literature 1, this description is incorporated into by referring to its content whole.

In figure 3, nonlinear optical sensor 135 and 140 is configured on photoconduction 130, and the scintillator arrays 105 with multiple flasher is configured under photoconduction 130.Self-evident for a person skilled in the art, present embodiment also can be applicable in the gamma-ray detector of the arbitrary nonlinear optical sensor using the SiPM comprising SiPM or array-like.2nd scintillator arrays 305 with multiple flasher is opposed with scintillator arrays 105, configures overlappingly with photoconduction 330, optical sensor 335 and 340.

In figure 3, if radiate mutually bury in oblivion gamma-rays from subject (omitting diagram), then they advance on the rightabout of mutual about 180 degree.Mutually bury in oblivion gamma-rays to be detected by flasher 100 and flasher 300 roughly simultaneously.Further, in set binding hours, if detect gamma-rays by flasher 100 and flasher 300, then interaction event 110 is determined.Like this, gamma-rays detection system detects gamma-rays by flasher 100 and flasher 300 simultaneously.But, in order to simply, at this, gamma-rays detection by flasher 100 is described.Self-evident for a person skilled in the art, illustrating in the gamma-rays detection that can be applicable to too by flasher 300 for flasher 100.

Turn back to Fig. 3, each optical sensor 135, optical sensor 140, optical sensor 335, optical sensor 340 are connected with data collection unit 350 or data collection unit 360.The corresponding waveform that data collection unit 350, data collection unit 360 are generated by the optical sensor 140 to response passage of scintillation light, optical sensor 135, optical sensor 340, optical sensor 335 carries out integration, thus generates digitized output valve.

Data collection unit 350, data collection unit 360 comprise with analog-digital converters such as the ∑-Δ of the sample rate action of 1 gigahertz ~ 5 gigahertz (sigma delta) transducers.Or data collection unit 350, data collection unit 360 also can comprise not with certain sample rate, and use the multiple thresholds sampler that voltage threshold is sampled to optical sensor waveform in triggering.Self-evident for those skilled in the art, not departing from the scope of present embodiment, other the method for sampling and data collection unit also can be comprised.Such as, also other respective passages can be used according to energy value and timing.Now, typically, in energy channel, the analog-digital converter of shaping filter and lower sample rate is used.In addition, timing channel typically adds up to the signal from multiple optical sensor.Then, by the timing signal input comparator after total, and by each arrival all rise time stamp of time-to-digit converter for each event.

If the output valve of obtaining, then output valve is sent to operational part 370, and decides the energy level of flasher and interaction event according to the method for following explanation.Then, output valve and the time of advent are stored in electronic storage device 375, and can be shown in display 385.Interface 380 also may be used for carrying out the formation of arithmetic unit 370 and the both sides of control or a side and operational part 370 is sent to both sides or a side of additional order.

Self-evident for a person skilled in the art, display 385 also can be CRT (Cathode Ray Tube: cathode ray tube) or LCD (Liquid Crystal Display: liquid crystal display) etc.Interface 380 can be for keyboard, mouse, trace ball, mike, touch screen etc. are connected the equipment both known played a role with central processor.Similarly, self-evident for a person skilled in the art, electronic storage device 375 also can be hard disk drive, CD-ROM, DVD disk, flash memory or other central processor.In addition, electronic storage device 375 can be dismantled from operational part 370 or be separated, or also can not install thereon.Electronic storage device 375 is connected with arithmetic unit via network, therefore, also can be arranged at other room or building etc., other place that operational part 370 is associated.

Fig. 4 is the figure of the structure of central processor in the PET device that relates to for illustration of embodiment.Operational part 370 comprises the handling part 480 that process is stored in data in the both sides of main storage 440 and ROM (Read OnlyMemory: read only memory) 450 or a side and order.In addition, handling part 480 also can process the information being stored in disk 410 or CD-ROM420.Exemplary handling part 480 can be the Xenon processor (registered trade mark) of American I ntel Inc. or the Opteron processor (registered trade mark) of AMD of the U.S..Self-evident for those skilled in the art, blood processor 480 also can be Pentium processor (registered trade mark) or Core 2Duo processor (registered trade mark) etc.Like this, corresponding with the method for gamma-ray detector order also can be stored in any one in disk 410, CD-ROM420, main storage 440 or ROM450.

In addition, operational part 370, in order to be connected with the network such as the Internet or personal network by interface, also can comprise the network interfaces 475 such as Intel Ethernet PRO NIC (registered trade mark) of American I ntel Inc..Display control part 430 also can be for connecting display 385 and the NVIDIA G-Force GTX EGA (graphics adapter) (registered trade mark) of the NVIDIA Inc. of the U.S. played a role.In addition, operational part 370 also can comprise for being connected and the I/O interface 490 played a role by other general-purpose interfaces such as keyboard 295, positioning equipment 285 or mike, trace ball, stick, touch screen.

Disk 410 and CD-ROM420 or DVD driver and bus 470 are interconnected by disk control part 460.Disk 410 can be hard disk drive or flash drive.Bus 470 also can be by industry standard architecture (ISA (Industry Standard Architecture :)), extended industry-standard architecture (EISA (Extended Industry Standard Architecture :)), screen electronic installation ANSI (VESA (Video Electronics Standards Association :)), ancillary equipment is interconnected (PCI (Peripheral Component Interconnect :)), the interconnective bus of all component parts of operational part 370.Due to the component parts about operational part 370 general function and functional be known, therefore, omit the description for simplicity.Certainly, also Freescale ColdFire, I.MX (registered trade mark) and arm processor (registered trade mark) etc. of Freescale Inc. of the U.S. can be used, other blood processor known by this technical field or hardware manufacturer and product.

In addition, exemplary operational part 370 also can be installed on the computer-readable mediums such as FPGA (Field Programmable Gate Array: field programmable gate array), special ASIC (Application Specific Integrated Circuit: special IC), microcontroller, PLD (Programmable Logic Device: PLD) or CD respectively.In addition, exemplary operational part 370 is hardware platforms of the computing equipments such as PC (Personal Computer: personal computer), and handling part 480 is the arbitrary blood processor known by the art such as IntelPentium processor (registered trade mark).The order being stored in the embodied on computer readable of any one in main storage 440, ROM450, disk 410 or CD-ROM420 provides as the element of application program, background formula or operating system or their combination, perform with the system interlink ground known by those skilled in the art such as handling part 480 and MicrosoftWindows Vista (registered trade mark), UNIX (registered trade mark), Solaris (registered trade mark), Linux (registered trade mark) and Apple Mac OS (registered trade mark).

The both sides of main storage 440 and ROM450 or a side support the record of operational part 370 and same function.Therefore, main storage 440 can be RAM (Random Access Memory: random access memory), flash memory, EPROM (Electrically Erasable Programmable Read Only Memory: EEPROM (Electrically Erasable Programmable Read Only Memo)) memorizer etc.On the other hand, ROM450 is the read only memory such as PROM.In addition, because such memorizer is known, omit the explanation of main storage 440 and ROM450 for simplicity.

Fig. 5 and Fig. 6 represents two general source rectangular histograms of the Compton scattering that can identify clearly between flasher.Fig. 5 represents and collects process by employing the reading of the scintillator arrays of the photomultiplier tube being divided into 4 parts and the general source rectangular histogram that obtains as optical system.In Figure 5,36 peak values represent 36 flashers that scintillator arrays comprises respectively.In addition, can see the line of the nearest peak value connected in scintillator arrays, the interaction event of the position between peak value produces by carrying out the event of Compton scattering in scintillator arrays.

Fig. 6 represents and collects process by employing the reading of the scintillator arrays of location sensitive type avalanche photodide and the general source rectangular histogram that obtains as analog data.In figure 6,64 peak values represent 64 flashers that the scintillation array of 8 × 8 comprises respectively.In addition, the interaction event be positioned between sharp-pointed peak value is carried out the event of Compton scattering by scintillator arrays and generates.In figure 6, the pattern of the line connecting nearest peak value can clearly be seen.This be based on to nearest flasher to the result of compton interaction of giving energy.

As concrete example, the case shown in Fig. 5 is discussed.In this case, 36 by other flasher individual form 6 × 6 scintillator arrays use be divided into the photomultiplier tube of 4 parts to read.Assuming that make to be divided into the photomultiplier tube of 4 parts to read scintillator arrays, and use the case being divided into the SiPM array of 4 parts to read.If use method in the past, then the general source rectangular histogram of Fig. 5 is divided into 36 regions, each region representation flasher.Energy correction coefficient may comprise gamma correction, is probably applicable to each flasher.In one embodiment, general source rectangular histogram is divided into multiple sub-pix (such as, 900).Then, try to achieve different gamma corrections according to calibration data (calibration date), and be applicable to each subpixel regions.

In another embodiment, after having tried to achieve the correction for all subregion according to calibration data, the mathematical function changed continuously as the function of the position in the rectangular histogram of general source by gamma correction has been derived.Now, mathematical function is counted as the method between center that interpolation calibrates the multiple regions used.

The PET device that the embodiment below illustrated relates to possesses scintillator arrays, multiple optical sensor, determination portion, storage unit and leading-out portion.Scintillator arrays has multiple flasher.The passage of scintillation light that multiple light sensors is interacted by gamma-rays and the flasher of predetermined energy value and generated.Determination portion is undertaken detecting by one or more optical sensor according to the diffusion by passage of scintillation light and the signal value exported from optical sensor, to be divided into the unit in the region of the quantity more than the quantity of flasher to determine the detection position of the interaction event of gamma-rays and flasher.Storage unit derives according to the signal value exported from optical sensor and adds up to signal value, and the total signal value of derivation and detection position are stored in storage part explicitly.Leading-out portion according to detect position and be stored in total signal value and the predetermined energy value of storage part explicitly, the unit in each region is derived to the corrected value of the energy value correcting interaction event.

In addition, in the PET device that embodiment relates to, determination portion also can, respectively for multiple interaction event, be determined to detect position according to the signal value exported from optical sensor.Storage unit also can derive for multiple interaction event respectively and add up to signal value, and the total signal value of derivation and detection position are stored in storage part explicitly.Leading-out portion also can according to detect position and be stored in multiple total signal values of storage part explicitly, the meansigma methods of the unit in each region of further derivation, and according to the meansigma methods derived and predetermined energy value, the unit in each region is derived to the corrected value of the energy value correcting interaction event.

In addition, in the PET device that embodiment relates to, when the optical sensor of output signal value is multiple, the position of signal value to each optical sensor that determination portion also can export by being pursuant to each optical sensor is weighted on average, thus determines to detect position.In addition, predetermined energy value also can derive as the unit of corrected value for each region with adding up to the ratio of signal value by leading-out portion.In addition, optical sensor also can comprise at least one silicon photomultiplier.In addition, PET device also can be TOF type.

In addition, each portion such as determination portion, storage unit and leading-out portion is such as provided in the operational part 370 using Fig. 3 to be described.

In addition, the PET device that another embodiment relates to possesses scintillator arrays, multiple optical sensor, determination portion and correction unit.Scintillator arrays has multiple flasher.The passage of scintillation light that multiple light sensors is generated by the gamma-rays to flasher input predetermined energy value.Determination portion is undertaken detecting by one or more optical sensor according to the diffusion by passage of scintillation light and the signal value exported from optical sensor, to be divided into the unit in the region of the quantity more than the quantity of flasher to determine the detection position of gamma-ray interaction event.Correction unit derives according to the signal value exported from optical sensor and adds up to signal value, and uses the total signal value of deriving and the detection position determined by determination portion, with reference to calibration data, and according to the corrected value corresponding with detecting position, corrects total signal value.Calibration data is the data correcting the corrected value of the energy value of interaction event for the unit definition in each region.

In addition, in the PET device that another embodiment relates to, when the optical sensor of output signal value is multiple, determination portion also can, by being weighted on average according to the position of signal value to each optical sensor exported by each optical sensor, be determined to detect position.In addition, correction unit also by being multiplied by corrected value to total signal value, can correct total signal value.In addition, PET device also can be TOF type.

In addition, each portion such as determination portion and correction unit is such as provided in the operational part 370 using Fig. 3 to be described.

In addition, the PET device that another embodiment relates to possesses scintillator arrays, multiple optical sensor, determination portion, storage unit and leading-out portion.Scintillator arrays has multiple flasher.The passage of scintillation light that multiple light sensors is generated by the gamma-rays to flasher input predetermined energy value.Determination portion is undertaken detecting by one or more optical sensor according to the diffusion by passage of scintillation light and the signal value exported from optical sensor, to be divided into the unit in the region of the quantity more than the quantity of flasher to determine the detection position of gamma-ray interaction event.Storage unit derives according to the signal value exported from optical sensor and adds up to signal value, and the total signal value of derivation and detection position are stored in storage part explicitly.Leading-out portion according to detect position and be stored in total signal value and the predetermined energy value of storage part explicitly, the corrected value of deriving the energy value correcting interaction event is as the mathematical function that changes of continuous ground of detection position.

In addition, the PET device that another embodiment relates to possesses scintillator arrays, multiple optical sensor, determination portion, storage unit and energy window (energy window) leading-out portion.Scintillator arrays has multiple flasher.The passage of scintillation light that multiple light sensors is generated by the gamma-rays to flasher input predetermined energy value.Determination portion is undertaken detecting by one or more optical sensor according to the diffusion by passage of scintillation light and the signal value exported from optical sensor, to be divided into the unit in the region of the quantity more than the quantity of flasher to determine the detection position of gamma-ray interaction event.Storage unit derives according to the signal value exported from optical sensor and adds up to signal value, and the total signal value of derivation and detection position are stored in storage part explicitly.Can window leading-out portion according to the total signal value and the predetermined energy value that detect position and be stored in explicitly storage part, to the unit derivation energy window in each region.

Fig. 7 A is the flow chart of the step representing the method that the PET device related to by embodiment is performed.Fig. 7 A represents the method for the group determining corrected value (being also referred to as " correction coefficient ").This corrected value is for determining the energy value of the interaction event detected by gamma-ray detector.In addition, this gamma-ray detector has and is configured in by the scintillator arrays that flicker element is formed, more than one nonlinear optical sensor.In addition, this gamma-ray detector use optical system collect process or analog data collect process.By the method shown in Fig. 7 A, determine the group of the corrected value for determining correct energy value, and by determining that the group of corrected value calibrates gamma-ray detector.In other words, such as, as shown in Figure 1, the object of the method shown in Fig. 7 A is, to each cell position of the sub-pix corresponding with the relative position of interaction event, determine generated by optical sensor and carry out the non-linear relation between the signal of integral and calculating and the energy value of interaction event.The quantity of the flasher that the number ratio scintillator arrays of cell position comprises is many.

In step S710, the PET device related to from embodiment produces the gamma-ray radiographic source with the 1st energy value (such as, 511keV), and detector accepts gamma-rays.This gamma-rays be from ²²na, ⁶⁸ge or ¹⁸the ray of the radiation source generation of F, typically, the scope of this radiogenic quantity of X-rays X is that tens of micromicrocurie is to number millicurie.In order to obtain sufficiently high counting rate, that is, in order in reasonable time (several tens minutes is to a few hours) collect need data and select radiogenic quantity of X-rays X.In addition, cause interaction event to overlap because counting rate is too high, its result can produce great error, selects radiogenic quantity of X-rays X in order to avoid this situation.

In step S720, gamma-rays interacts with the scintillator arrays be made up of flicker element, and generate passage of scintillation light, the passage of scintillation light generated is detected by more than one optical sensor.The signal value (arbitrary unit) of the data collection unit that embodiment relates to by exporting from optical sensor each optical sensor collection, as the energy value being opportunity with interaction event.Such as, Fig. 8 A is represented and to be occurred by the gamma-rays of 511keV contact scintillator arrays, from the typical pulse of the optical sensor of the incidence of response light.In addition, Fig. 8 B-1 represents the figure of the time shaft changing Fig. 8 A, and Fig. 8 B-2 represents the figure of the information of the energy corresponding with the pulse shown in Fig. 8 A.As shown in Fig. 8 B-1, obtain the information of timing from the rising edge of pulse, in addition, obtained the information of energy by the integration of pulse.

In step S730, the PET device that embodiment relates to, according to the signal value exported from each optical sensor, determines the relative position of flasher event and adds up to signal value.Fig. 9 A and Fig. 9 B represents the structure of the gamma-ray detector that embodiment relates to.In addition, Fig. 9 A and Fig. 9 B represents a method of the relative position determining interaction event.Fig. 9 A and Fig. 9 B is two figure of gamma-ray detector, represents the position relationship of flasher, photoconduction and optical sensor.

Passage of scintillation light from a flasher is diffused on multiple optical sensor by photoconduction.The PET device that embodiment relates to according to the ratio of the signal received by different optical sensors, can calculate the relative position of interaction event as following.

x＝(∑x _i Signal _i)/∑Signal _i …(1)

y＝(∑y _i Signal _i)/∑Signal _i …(2)

At this, Signal _ithe signal value exported from i-th optical sensor, x _iand y _iit is the position at the center of i-th optical sensor.In addition, PET device also can use other algorithm to decide the relative position of the interaction event by multiple light sensors.In addition, the PET device that embodiment relates to can according to receive interaction event passage of scintillation light each optical sensor in the total (total signal value) of signal value, calculate the total amount of the energy value of interaction event.

In one embodiment, relative position decides as the position that one of cell position with stated number is corresponding.At this, the stated number of this unit (sub-pix) position is than many by the quantity of the flicker element in the scintillator arrays that flicker element is formed.

In step S740, the total signal value relevant to interaction event and the relative position of the interaction event determined in step S730 are stored in storage part by PET device that embodiment relates to explicitly.

In step S750, the PET device that embodiment relates to repeats step S710 ~ S740 for multiple interaction event.Figure 10 A represents general source rectangular histogram.In addition, Figure 10 B represents the flasher ID look-up table corresponding with general source rectangular histogram.As shown in Figure 10 A, in the past, represent that the general source rectangular histogram of the frequency of interaction event generates according to preserved data each interaction event.General source rectangular histogram represents each flasher other peak value.In addition, by configuration flasher or optical sensor etc., the pattern of unique distortion is generated.As shown in Figure 10 B, PET device by becoming region to general source histogram divion, thus can use general source rectangular histogram to determine the flasher being considered to interaction event occurs.The all interaction events meeting identical region are all assigned to identical flasher.Like this, generate look-up table, the relative position of the interaction event in the rectangular histogram of general source can be converted to the position of flasher by PET device.

In one embodiment, each region in the general source rectangular histogram shown in Figure 10 A is divided into multiple unit (sub-pix) again.The PET device that embodiment relates to determines the corrected value of the energy value correcting interaction event to each sub-pix.

In step S760, the PET device that embodiment relates to, according to the data of stored interaction event, determines the meansigma methods of the total signal value relevant to multiple interaction event for each relative position (cell position of sub-pix).In addition, PET device is stored in storage part by adding up to the meansigma methods of signal value explicitly with gamma-ray 1st energy value being used for generating interaction event.

In step S770, the PET device that embodiment relates to, according to the meansigma methods of the total signal value determined for each relative position and the 1st energy value, determines corrected value to each relative position.Such as, PET device, by the energy value (such as, 511keV) of regulation and the ratio for the meansigma methods (arbitrary unit) of the total signal value of the cell position of sub-pix, is set as the corrected value relevant to this cell position.

In step S780, the PET device that embodiment relates to, also for other the gamma-rays of energy value with regulation, repeats step S710 ~ S770, determines the corrected value corresponding with the energy value of each regulation, each cell position.Like this, after step S77, last at calibration process, the PET device that embodiment relates to, to each unit (sub-pix) position, such as, has data value { S _i, E _igroup.At this, S _iadd up to signal value (arbitrary unit), E _ienergy value (keV).PET device uses the group of this data value, to each cell position generate such as shown in Figure 1, by signal value and the nonlinear curve correcting energy value afterwards and be associated.Further, PET device can be used in the nonlinear curve that each cell position generates, and converts the signal value of interaction event to energy value, and can compensate the non-linear of SiPM response.

As described above, the PET device that another embodiment relates to derives after corrected value according to calibration data each cell position, using the function as the position in the rectangular histogram of general source, the mathematical function that changes continuously derives as gamma correction.Now, mathematical function is counted as interpolation in the center method each other of calibrating the multiple regions used.

In another embodiment, use the gamma-ray radiographic source with certain energy, carrying out in the process of this parsing, also resolve for another energy simultaneously.Now, PET device can use, edge, Compton or backscattering peak value such, the characteristic point that can find the energy both known in acquired spectrum, calibrate the nonlinear response of gamma-ray detector.

Fig. 7 B is the flow chart of the step representing the method that the PET device related to by another embodiment is performed.As shown in Figure 7 B, the PET device that another embodiment relates to uses the corrected value obtained by the method shown in Fig. 7 A, corrects the energy value of interaction event.

In step S715, the detector of the PET device that embodiment relates to accepts the gamma-rays produced from certain radiographic source.

In step S725, if gamma-rays contacts with the scintillator arrays be made up of flicker element, then generate passage of scintillation light, the passage of scintillation light generated is detected by more than one optical sensor.The data collection unit that embodiment relates to is collected by each optical sensor the signal value exported from optical sensor (arbitrary unit), as with the gamma-ray interaction event energy value that is opportunity.

In step S735, the PET device that embodiment relates to, according to the signal value exported from each optical sensor, determines with the relative position of gamma-ray interaction event as described above and adds up to signal value.Relative position is decided to be the position corresponding with one of cell position of stated number.Relative position is converted into the cell position of the correspondence obtained in multiple cell positions of calibration data.The stated number of unit (sub-pix) position is than many by the quantity of the flicker element in the scintillator arrays that flicker element is formed.

In step S745, the total signal value (value determined in step S735) that the PET device that embodiment relates to stores according to each cell position corresponding with relative position and calibration data, calculate the correcting energy value for interaction event.At this, calibration data is the data defined the signal value of each cell position and the non-linear relation of energy value.Such as, calibration data is in fact define the nonlinear curve of the relation representing signal value and energy value.In one embodiment, the PET device that embodiment relates to, by the total signal value determined in step S735, uses nonlinear curve to be multiplied by corrected value, thus obtains the energy value after correcting.Self-evident for a person skilled in the art, before applying embodiment described herein, not departing from the scope of present embodiment, also can apply additional gain or offset correction to signal.

Than the point of system excellence be in the past: according to embodiment described herein, more excellent gamma correction can be carried out, can energy resolution be improved.For PET, the improvement of energy resolution can reduce scattering fraction in other words, finally, can improve picture quality.

In addition, the PET device that embodiment relates to also possesses the energy window leading-out portion of the unit in each region being derived to energy window.Can window leading-out portion according to the total signal value and the predetermined energy value that detect position and be stored in explicitly storage part, for the unit derivation energy window in each region.At this, PET device also can arrange energy window, and signal value is only using the object of the signal in energy window as process.This energy window such as uses by presetting fixing higher limit and lower limit etc.As described above, gamma-rays incides which position in a flasher, can have an impact to signal value.Therefore, the total signal value that the PET device that embodiment relates to is preserved according to the unit in each region, such as, and can by the energy window to add up to the Rack centered by signal value, the unit according to each region decides.

In addition, also can pass through according to and detect the total signal value that position be stored in storage part explicitly by window leading-out portion, generate energy distribution curve, and the regulation ratio from the area of central authorities to entire area under the energy distribution curve generated is added up to, thus derive energy window.

As described above, in one embodiment, provide for determining energy in order to determine event and the method for the correction coefficient used.Event is detected by gamma-ray detector.Gamma-ray detector have be configured in by the scintillator arrays that flicker element is formed, at least one nonlinear optical sensor.Gamma-ray detector uses optical system to collect process or analog data collects process.Above-mentioned method comprises the gamma-ray step that (a) generates the energy value with the 1st regulation.In addition, above-mentioned method comprises the step that (b) obtains the respective signal value generated by least one nonlinear optical sensor.At least one nonlinear optical sensor respond respectively the generation of presentation of events, the gamma-ray arrival generated, and response accepts from the passage of scintillation light radiated by least one flasher the array that flicker element is formed, and generates respective signal value.In addition, above-mentioned method comprises (c) according to the signal value obtained respectively by least one nonlinear optical sensor, determines the relative position of event and the step adding up to signal value.This relative position is one of cell position of stated number, and the stated number of cell position is than many by the quantity of the flicker element in the array that flicker element is formed.In addition, above-mentioned method comprises the step that (d) will add up to signal value to store explicitly with the cell position determined.In addition, above-mentioned method comprises (e) to generate stored event data, for multiple event, repeats the step obtaining step, deciding step and storing step.In addition, above-mentioned method comprises (f) to each cell position, according to stored event data, determines the step of the average aggregate signal value of the energy value for the 1st regulation.In addition, above-mentioned method comprises (g) to each cell position, decides the step of correction coefficient according to determined average aggregate signal value and the 1st energy value specified.

According to a mode of above-mentioned embodiment, above-mentioned method also comprises the 2nd gamma-ray step that (1) generates the energy value with the 2nd regulation.In addition, above-mentioned method comprises (2) in order to for each cell position, determines 2nd correction coefficient corresponding with the energy value that the 2nd specifies, repeats the step of step (a) ~ (g).In addition, above-mentioned method comprises (3) to each cell position, by the step that the corrected value of each decision stores explicitly with the energy value of corresponding regulation.

According to another way, above-mentioned method also comprises each cell position, according to stored correction coefficient, determines the step of the non-linear relation of signal value and energy value.

In addition, according to another way, determine that the above-mentioned step of relative position comprises in order to and the step of cell position of determining stated number one of corresponding with relative position.

In addition, according to another way, determine the above-mentioned step of relative position comprise (1) according to accept the passage of scintillation light corresponding with event, the respective x-y position of at least one nonlinear optical sensor, calculate average weighted step.On average by accept the passage of scintillation light corresponding with event, at least one nonlinear optical sensor separately, the corresponding signal value obtained provides weighted value.In addition, determine that the above-mentioned step of relative position comprises (2) by adding up to respective, the acquired signal value of at least one nonlinear optical sensor, thus determine the step adding up to signal value.

In addition, according to another way, determine that the above-mentioned step of corrected value comprises the corrected value corresponding with the energy value that the 1st specifies of each cell position, the step that the energy value as the 1st regulation is tried to achieve with the ratio of the total signal value determined for cell position.

In addition, according to another way, at least one nonlinear optical sensor comprises at least one silicon photomultiplier.

In another embodiment, provide the computer-readable medium preserving computer program, this program is performed by computer.Computer determines the correction coefficient of the energy for determining event.Event is detected by gamma-ray detector.Gamma-ray detector has at least one the nonlinear optical sensor be configured in by the scintillator arrays that flicker element is formed.Gamma-ray detector uses optical system to collect process or analog data collects process.By above-mentioned program, above-mentioned computer performs the step that (1) receives the respective signal value generated by least one nonlinear optical sensor.At least one nonlinear optical sensor respond respectively the generation of presentation of events, the gamma-ray arrival generated, and response accept from the passage of scintillation light radiated by least one flasher the array that flicker element is formed, generate respective signal value.In addition, computer performs (2) according to respectively from the signal value that at least one nonlinear optical sensor obtains, and determines the relative position of event and the step adding up to signal value.This relative position is one of cell position of stated number, and the stated number of cell position is than many by the quantity of the flicker element in the array that flicker element is formed.In addition, computer performs (3) to the step adding up to signal value to store explicitly with the cell position determined.In addition, computer performs (4) to generate stored event data, for multiple event, repeats the step obtaining step, deciding step and storing step.In addition, computer performs (5) to each cell position, according to stored event data, determines the step of the average aggregate signal value of the energy value for the 1st regulation.In addition, computer performs (6) for each cell position, decides the step of correction coefficient according to determined average aggregate signal value and the 1st energy value specified.

In another embodiment, provide for determining energy in order to determine event and the method for the correction coefficient used.Event is detected by gamma-ray detector.Gamma-ray detector has at least one the nonlinear optical sensor be configured in by the scintillator arrays that flicker element is formed.Above-mentioned method comprises (1) and generates many gamma-ray steps.In addition, above-mentioned method comprises the step that (2) obtain the respective signal value generated by least one nonlinear optical sensor.At least one nonlinear optical sensor respond respectively the generation of presentation of events, the gamma-ray arrival generated, and response accept from the passage of scintillation light radiated by least one flasher the array that flicker element is formed, generate respective signal value.In addition, above-mentioned method comprises (3) according to respectively from the signal value that at least one nonlinear optical sensor obtains, and determines the relative position of event and the step adding up to signal value.This relative position is one of cell position of stated number, and the stated number of cell position is than many by the quantity of the flicker element in the array that flicker element is formed.In addition, above-mentioned method comprises (4) according to for the total signal value of the cell position corresponding with determined relative position and the calibration data that stores, calculates the step of the correcting energy value for event.The calibration data stored defines the signal value of each cell position and the non-linear relation of energy value.

In another embodiment, provide the computer-readable medium preserving computer program, this program is performed by computer.Computer determine with by be configured in by the scintillator arrays that flicker element is formed, the gamma-ray detector with at least one nonlinear optical sensor and the corresponding correcting energy value of the event carrying out detecting.By above-mentioned program, above-mentioned computer performs the step that (1) receives the respective signal value generated by least one nonlinear optical sensor.At least one nonlinear optical sensor respond respectively the generation of presentation of events, the gamma-ray arrival generated, and response accept from the passage of scintillation light radiated by least one flasher the array that flicker element is formed, generate respective signal value.In addition, computer performs (2) according to respectively from the signal value that at least one nonlinear optical sensor obtains, and determines the relative position of event and the step adding up to signal value.This relative position is one of cell position of stated number, and the stated number of cell position is than many by the quantity of the flicker element in the array that flicker element is formed.In addition, computer performs (3) according to for the total signal value of the cell position corresponding with determined relative position and the calibration data that stores, calculates the step of the correcting energy value for event.The calibration data stored defines the signal value of each cell position and the non-linear relation of energy value.

In another embodiment, provide for determining energy in order to determine event and the method for the correction coefficient used.Event is detected by gamma-ray detector.Gamma-ray detector has at least one the nonlinear optical sensor be configured in by the scintillator arrays that flicker element is formed.Above-mentioned method comprises the gamma-ray step that (a) generates the energy value with the 1st regulation.In addition, above-mentioned method comprises the step that (b) obtains the respective signal value generated by least one nonlinear optical sensor.At least one nonlinear optical sensor respond respectively the generation of presentation of events, the gamma-ray arrival generated, and response accept from the passage of scintillation light radiated by least one flasher the array that flicker element is formed, generate respective signal value.In addition, above-mentioned method comprises (c) according to the signal value obtained respectively by least one nonlinear optical sensor, determines the relative position of event and the step adding up to signal value.This relative position is one of cell position of stated number, and the stated number of cell position is than many by the quantity of the flicker element in the array that flicker element is formed.In addition, above-mentioned method comprises (d) and carries out adding up to signal value and the cell position determined the step stored explicitly.In addition, above-mentioned method comprises (e) to generate stored event data, for multiple event, repeats the step obtaining step, deciding step and storing step.In addition, above-mentioned method comprises (f) according to stored event data and the 1st energy value specified, by the parameter of Mathematical Correction function changed continuously, determines the step for the function by the position in the array that flicker element is formed.Spatial variations in the total signal value of the event that Mathematical Correction function representation obtains.

In addition, the above-mentioned method of this embodiment comprises each event, and the Mathematical Correction function determined and the relative position determined of use case, decide the step of the energy of event.

According to the Positron emission tomography device of at least one embodiment above-described, and by the method that Positron emission tomography device performs, energy resolution can be improved.

Although the description of several embodiment of the present invention, but these embodiments are pointed out as an example, the scope be not intended to limit the present invention.These embodiments can be implemented with other various forms.In the scope of main idea not departing from invention, various omission, displacement, change can be carried out.These embodiments or its distortion are contained in scope of invention or main idea, similarly, are contained in invention described in claim and equal scope thereof.

Claims

1. a Positron emission tomography device, is characterized in that, possesses:

Scintillator arrays, has multiple flasher;

Multiple optical sensor, detects the passage of scintillation light generated by the gamma-rays to above-mentioned flasher input predetermined energy value;

Determination portion, undertaken detecting by one or more above-mentioned optical sensor and the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of the interaction event of above-mentioned gamma-rays and flasher according to the diffusion by above-mentioned passage of scintillation light;

Storage unit, derives according to the signal value exported from above-mentioned optical sensor and adds up to signal value, and the total signal value of derivation and above-mentioned detection position are stored in storage part explicitly; And

Leading-out portion, is stored in total signal value and the afore mentioned rules energy value of storage part explicitly according to above-mentioned detection position, the unit of each above-mentioned zone is derived to the corrected value of the energy value correcting above-mentioned interaction event.

2. Positron emission tomography device according to claim 1, is characterized in that,

Above-mentioned determining section safety pin, to multiple above-mentioned interaction event, determines above-mentioned detection position according to the signal value exported from above-mentioned optical sensor,

Above-mentioned storage unit for multiple above-mentioned interaction event, derives above-mentioned total signal value respectively, and the total signal value of derivation and above-mentioned detection position are stored in storage part explicitly,

Above-mentioned leading-out portion is from being stored in multiple total signal values of storage part explicitly with above-mentioned detection position, the meansigma methods of the unit of each above-mentioned zone of further derivation, and according to the meansigma methods derived and afore mentioned rules energy value, the unit of each above-mentioned zone is derived to the corrected value of the energy value correcting above-mentioned interaction event.

3. Positron emission tomography device according to claim 1 and 2, is characterized in that,

When the optical sensor exporting above-mentioned signal value is multiple, above-mentioned determination portion, by being weighted on average according to the position of signal value to each optical sensor exported by each optical sensor, determines above-mentioned detection position.

4. Positron emission tomography device according to claim 1, is characterized in that,

The ratio of afore mentioned rules energy value and above-mentioned total signal value as above-mentioned corrected value, is derived the unit of each above-mentioned zone by above-mentioned leading-out portion.

5. Positron emission tomography device according to claim 1, is characterized in that,

Above-mentioned optical sensor comprises at least one silicon photomultiplier.

6. Positron emission tomography device according to claim 1, is characterized in that,

This Positron emission tomography device is TOF type and time-of-flight type.

7., by the method that Positron emission tomography device performs, this Positron emission tomography device possesses gamma-ray detector, and this gamma-ray detector possesses: scintillator arrays, has multiple flasher; Multiple optical sensor, is detected the passage of scintillation light generated by the gamma-rays to above-mentioned flasher input predetermined energy value, the method is characterized in that, comprising:

Collecting process, by the diffusion of above-mentioned passage of scintillation light by the gamma-rays of one or more above-mentioned light sensors predetermined energy value, and collects the signal value exported from above-mentioned optical sensor;

Determine operation, according to the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of above-mentioned gamma-ray interaction event;

Preserve operation, derive according to the signal value exported from above-mentioned optical sensor and add up to signal value, and the total signal value of derivation and above-mentioned detection position are stored in storage part explicitly;

Repeat operation, repeat above-mentioned collecting process, above-mentionedly determine operation and above-mentioned preservation operation;

Meansigma methods derives operation, is stored in the total signal value of storage part explicitly, derives the meansigma methods of the unit of each above-mentioned zone according to above-mentioned detection position; And

Corrected value derives operation, according to above-mentioned meansigma methods and afore mentioned rules energy value, the unit of each above-mentioned zone is derived to the corrected value of the energy value correcting above-mentioned interaction event.

8. method according to claim 7, is characterized in that,

Also comprise the 2nd corrected value and derive operation, for 2nd energy value different from the 1st energy value as afore mentioned rules energy value, repeat above-mentioned generation process, above-mentioned collecting process, above-mentionedly determine that operation, above-mentioned preservation operation, above-mentioned repetition operation, above-mentioned meansigma methods derive operation, above-mentioned corrected value derives operation, the corrected value corresponding with above-mentioned 2nd energy value is derived to the unit of each above-mentioned zone.

9. a Positron emission tomography device, is characterized in that, possesses:

Scintillator arrays, has multiple flasher;

Determination portion, undertaken detecting by one or more above-mentioned optical sensor and the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of above-mentioned gamma-ray interaction event according to the diffusion by above-mentioned passage of scintillation light;

Correction unit, derive according to the signal value exported from above-mentioned optical sensor and add up to signal value, use the total signal value of deriving and the detection position determined by above-mentioned determination portion, reference corrects the calibration data of the corrected value of the energy value of above-mentioned interaction event to the unit definition of each above-mentioned zone, and according to the corrected value corresponding with above-mentioned detection position, correct above-mentioned total signal value.

10. Positron emission tomography device according to claim 9, is characterized in that,

11. Positron emission tomography devices according to claim 9 or 10, is characterized in that,

Above-mentioned correction unit, by being multiplied by above-mentioned corrected value to above-mentioned total signal value, corrects above-mentioned total signal value.

12. Positron emission tomography devices according to claim 9, is characterized in that,

Described Positron emission tomography device is TOF type.

13. 1 kinds of methods performed by Positron emission tomography device, this Positron emission tomography device possesses gamma-ray detector, and this gamma-ray detector possesses: scintillator arrays, has multiple flasher; Multiple optical sensor, is detected the passage of scintillation light generated by the gamma-rays to above-mentioned flasher input predetermined energy value, the method is characterized in that, comprising:

Determine operation, undertaken detecting by one or more above-mentioned optical sensor and the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of above-mentioned gamma-ray interaction event according to the diffusion by above-mentioned passage of scintillation light; And

Correcting process, derive according to the signal value exported from above-mentioned optical sensor and add up to signal value, use the total signal value of derivation and determine by above-mentioned the detection position that operation is determined, and the calibration data of the corrected value of the energy value of above-mentioned interaction event is corrected with reference to the unit definition for each above-mentioned zone, according to the corrected value corresponding with above-mentioned detection position, correct above-mentioned total signal value.

14. 1 kinds of Positron emission tomography devices, is characterized in that possessing:

Scintillator arrays, has multiple flasher;

Storage unit, derives according to the signal value exported from above-mentioned optical sensor and adds up to signal value, and the total signal value of derivation and above-mentioned detection position are kept at explicitly in storage part; And

Leading-out portion, is kept at total signal value in storage part and afore mentioned rules energy value explicitly according to above-mentioned detection position, and the corrected value of deriving the energy value correcting above-mentioned interaction event is as detecting the function of position and the mathematical function that changes continuously.

15. 1 kinds of methods performed by Positron emission tomography device, this Positron emission tomography device possesses gamma-ray detector, and this gamma-ray detector possesses: scintillator arrays, has multiple flasher; Multiple optical sensor, is detected the passage of scintillation light generated by the gamma-rays to above-mentioned flasher input predetermined energy value, the method is characterized in that, comprising:

Determine operation, undertaken detecting by one or more above-mentioned optical sensor and the signal value exported from above-mentioned optical sensor, to be divided into the unit in the region of the quantity more than the quantity of above-mentioned flasher to determine the detection position of above-mentioned gamma-ray interaction event according to the diffusion by above-mentioned passage of scintillation light;

Preserve operation, derive according to the signal value exported from above-mentioned optical sensor and add up to signal value, and the total signal value of derivation and above-mentioned detection position are stored in storage part explicitly; And

Derive operation, be kept at total signal value in storage part and afore mentioned rules energy value explicitly according to above-mentioned detection position, the corrected value of deriving the energy value correcting above-mentioned interaction event is as the mathematical function that changes of continuous ground of detection position.

16. 1 kinds of Positron emission tomography devices, is characterized in that possessing:

Scintillator arrays, has multiple flasher;

Storage unit, derives according to the signal value exported from above-mentioned optical sensor and adds up to signal value, and the total signal value of derivation and above-mentioned detection position are stored in explicitly in storage part; And

Can window leading-out portion, be stored in total signal value and the afore mentioned rules energy value of storage part explicitly according to above-mentioned detection position, energy window is derived to the unit of each above-mentioned zone.