CN206075356U - The device of PET linear attenuation coefficients is obtained based on CT images - Google Patents

Abstract

The utility model is related to a kind of device that PET linear attenuation coefficients are obtained based on CT images, it is scanned in by decay scale die body is separately positioned on CT detection systems and PET detection systems, obtain CT reconstruction images and PET penetrates data, the parametrization MU value of each pixel of decay scale die body can be obtained according to CT reconstruction images and transformational relation modeling, it is then based on the parametrization MU value and actual measurement penetrates data and builds multidimensional equation and solve the accurate model parameter for obtaining HU MU transformational relations, can be used for clinical PET image reconstruction Jing after actual measurement PET image data checking.The utility model guarantees PET image quality, the linear attenuation coefficient estimated bias caused due to the intrinsic mismatch of CT continuums and PET single energies, CT contrast preparation and implanted metal thing etc. in clinical practice are solved the problems, such as thoroughly, PET image artifact and quantitative information deviation are avoided, clinical diagnosis diagnosis rate is improved.

Description

The device of PET linear attenuation coefficients is obtained based on CT images

Technical field

The utility model belongs to the instrument for radiodiagnosis, the technical field for such as combining with radiotherapy equipment, More particularly to a kind of structure rebuilds the exact scale scheme of required MU values to realize the accurate of MU values from the HU values of CT images to PET Estimate, guarantee that the accuracy of the picture quality and quantitative information of PET imaging systems obtains PET linear attenuations systems based on CT images Several devices.

Background technology

In positron emission fault（PET）In imaging system, it is possible to use X ray computer tomography（CT）Imaging system Reconstruction image HU value is determining the linear attenuation coefficient MU values required for PET image reconstruction for correction for attenuation.Correction for attenuation Change a kind of maximum correction in generating as PET image to image information, the precision of linear attenuation coefficient is to obtaining quantitative PET Image is most important.Additionally, basis of the linear attenuation coefficient also as the most wide scatter correction techniques of current application, to improving The image quality performances such as the contrast and resolution ratio of PET image are extremely important.

In view of the HU values of CT images characterize material to continuous low energy X ray photon（Such as 30-140keV）Average linear decline Subtract coefficient, and material is to things such as the atomic number of the decay of X-ray or gamma rays and the energy of ray and material itself, density Rationality can have relation, there is theoretically no HU values to the absolute standard to single energy 511keV gamma photons linear attenuation coefficients Relation is parsed really.Therefore, using the Eur J Nucl in C Burger et al. more than the existing correction for attenuation technology based on CT images Med (2002) 29:Seminars in Nuclear Medicine (2003) of 922-927, PE Kinahan et al. The Phys Med Biol (2012) 57 (9) of 166-179 and M Abella et al.:Bilinearity proposed in 2477-2490 or Three approximate linear function of person realizing HU values to the conversion of MU values, but, it is this approximate to the MU values that generate for PET image Estimate not accurate enough, on the other hand, the characteristics of being limited to CT and be imaged, CT image HU values can not linearly distinguish contrast preparation and implantation The non-human suck tissue such as metal object, in turn resulting in corresponding MU values, to calculate deviation larger, easily cause PET image artifact and SUV value deviations.

Utility model content

The technical problem that the utility model is solved is, in prior art, adopts the correction for attenuation technology based on CT images more Bilinearity or three approximate linear functions are realizing HU values to the conversion of MU values, and caused this approximate to for PET image The estimation of the MU values of generation is not accurate enough, meanwhile, the characteristics of being limited to CT and be imaged, CT image HU values can not linearly distinguish radiography The non-human suck tissue such as agent and implanted metal thing, in turn resulting in corresponding MU values, to calculate deviation larger, easily causes PET image The problem of artifact and SUV value deviations, and then PET linear attenuation coefficients are obtained based on CT images there is provided a kind of optimization structure Device.

The technical scheme adopted by the utility model is, a kind of device that PET linear attenuation coefficients are obtained based on CT images, Including moveable scanning bed, PET detection systems and CT detection systems, the PET detection systems and CT detection systems sequentially set Put, the PET detection systems and CT detection systems are connected to Computerized image processing system, described scanning bed upper by liftable Supporting construction is detachably provided with decay scale die body, it is described it is scanning bed on be also detachably provided with and penetrate scanning means.

Preferably, the decay scale die body includes filled water container, can inject contrast container and implantable metal Thing plug-in unit.

Preferably, it is described to penetrate the driving means that scanning means includes detachably being located on scanning bed, the driving means Horizontally disposed rotary shaft is provided with, the end vertical of the rotary shaft is provided with support arm, and the support arm is relative to rotary shaft End horizontal be provided with positron emission line source.

The utility model provides a kind of device that PET linear attenuation coefficients are obtained based on CT images of optimization structure, leads to Cross and the decay scale die body in the device is scanned in CT detection systems and PET detection systems respectively, obtain CT reconstructions Image, i.e. HU values, and PET penetrate data, are decayed according to CT reconstruction images and to the transformational relation modeling of HU values to MU values The parametrization MU value of scale die body each pixel, is then based on the parametrization MU value and actual measurement penetrates data and builds multidimensional equation simultaneously Solution obtains the accurate model parameter of HU-MU transformational relations, and the parameter can be used for clinic Jing after actual measurement PET image data checking PET image reconstruction.The utility model provides device and the side that accurate HU-MU transformational relations are obtained by scale of complete set Method, it is ensured that PET system image quality, thoroughly solve in clinical practice due to CT continuums and PET single energies it is intrinsic not The linear attenuation coefficient that matching, CT contrast preparation and implanted metal thing etc. cause estimates higher or low problem, it is to avoid PET schemes As artifact and quantitative information（Such as SUV values etc.）Deviation, so as to reducing clinical diagnosis misdiagnosis rate and improving clinical diagnosis diagnosis rate.

Description of the drawings

Fig. 1 is structural representation of the present utility model；

Fig. 2 is the decay scale die body mounting structure schematic diagram in the utility model for the measurement of CT image HU values；

Fig. 3 is for penetrating the mounting structure schematic diagram for penetrating scanning means of measurement in the utility model；

Fig. 4 is tied to be used for penetrating the decay scale die body of measurement and penetrating the overall installation of scanning means in the utility model Structure schematic diagram；

Wherein, in Fig. 1 to Fig. 4, the central region of PET detection systems of the present utility model and CT detection systems is related to base Directrix, central region are numbered 0.

Specific embodiment

The utility model is described in further detail with reference to embodiment, but protection domain of the present utility model is simultaneously Not limited to this.

As illustrated, the utility model is related to a kind of device that PET linear attenuation coefficients are obtained based on CT images, including can Mobile scanning bed 130, PET detection systems 110 and CT detection systems 120, the PET detection systems 110 and CT detection systems 120 are connected to Computerized image processing system 140, are detachably provided with by lifting support structure 152 on described scanning bed 130 Decay scale die body 151, is also detachably provided with described scanning bed 130 and penetrates scanning means 160.

In the utility model, CT detection systems 120 mainly include x-ray source, X-ray detector, slip ring and data read-out The structures such as electronic circuit.

In the utility model, PET detection systems 110 are mainly included based on the detector by scintillation crystal and light sensing technique The structure such as ring and data read-out electronic circuit.

In the utility model, the main elevating mechanism and horizontal supporting mechanism for including longitudinal direction of lifting support structure 152, Generally, need to only complete to drive decay scale die body 151 to lift and the firm effect for supporting.In the utility model, The lift work of lifting support structure 152 can be completed in the form of elevating lever is set in pedestal.

In the utility model, scanning bed 130 include, for carrying the bed board 131 of patient, driving being typically provided under bed board 131 Bed board 131 makees the device of 131 position of horizontal axis motion and the device 132 for moving vertically and record bed board, such as records respectively The displacement record device that horizontal axis is moved and moved vertically.

In the utility model, Computerized image processing system 140 mainly includes controlling for the PET of Data acquisition and Proclssing Unit 141 and CT control units 142, the control units 143 for controlling scanning bed 130 running, for controlling image reconstruction and figure As display and the central location 144 analyzed etc., Computerized image processing system 140 provides user interface to control PET scan, CT Scanning and PET/CT scannings.

The decay scale die body 151 includes filled water container, can inject contrast container and implantable metal object is inserted Part.

In the utility model, decay scale die body 151 is used to simulate human body, comprising being equal to Human Lung, liver, muscle, fat The filled water container of the major organs such as fat, bone, contrast container and implantable metal object plug-in unit can be injected.

In the utility model, the concrete moulding of scale die body 151 of decaying can be according to the understanding of those skilled in the art certainly Row is arranged, as long as reaching the purpose of simulation human body.

Described to penetrate the driving means 164 that scanning means 160 includes detachably being located on scanning bed 130, described driving fills Put 164 and be provided with horizontally disposed rotary shaft 163, the end vertical of the rotary shaft 163 is provided with support arm 162, the support Arm 162 is provided with positron emission line source 161 relative to the end horizontal of rotary shaft 163.

In the utility model, scanning means 160 is penetrated for realizing 161 motion control of line source, the record of position and penetrating Data acquisition, generally comprises positron emission line source 161 and supports and drive the device that line source 161 rotated around PET central shafts.

Operation principle of the present utility model is as follows：

A kind of method for obtaining PET linear attenuation coefficients based on CT images, the method comprising the steps of：

Step 1.1：In the central region 0 of the PET detection systems 110 and CT detection systems 120 being sequentially arranged, scanning is set Bed 130, arranges decay scale die body 151 on scanning bed 130 and penetrates scanning means 160；Set up HU-MU transformation model MU= TF(HU)；The PET detection systems 110 and CT detection systems 120 are connected to Computerized image processing system 140；

In the utility model, in step 1.1, need to build high-precision HU-MU transformation models, such as MU=TF (HU), With provide CT image HU values to material during PET scan accurately estimating to the linear attenuation coefficient MU values of 511keV gamma photons pair Meter, the HU-MU transformation models are based on certain principles, it is necessary to consider that the type of concrete X-ray tube, high pressure in actual CT scan The parameters such as kVp, tube current mA and filter type are special to impact, the HU values of CT images and the material atom for exporting X-ray energy spectrum Property and density multiple mapping relation and material to the decay of continuous X-rays and to it is single can 511keV gamma ray decays thing Reason property difference, there is provided the accurate of the HU values of certain CT scan parameter and material type based on given x-ray source to MU values turns Change.

Step 1.2：The decay scale die body 151 is only placed on the central region 0 of CT detection systems 120, decay is carved The central shaft alignment of the central shaft and CT detection systems 120 of degree die body 151；Choose some groups of CT scan parameters and sequentially carry out and sweep Retouch, the HU value images in acquisition CT imaging systems under all preset sweep parameters；

In the utility model, CT imaging systems include CT detection systems 120, scanning bed 130 and Computer Image Processing system System 140.

In the utility model, in step 1.2, the HU value of decay scale die body 151 can be obtained using CT detection systems Image, determines the combination of all preset sweep parameters kVp, mA of the CT detection systems 120 and filter type etc., and such as kVp takes It is 60,70,80,90,100,110,120,130 to be worth or 140, mA value is 50,100,200 or 300, then will decay scale mould Body 151 is on scanning bed 130, and adjusts scanning bed 130 position so that decay scale die body 151 is placed in CT detection systems 120 central region 0, that is, the central shaft alignment of the central shaft and CT detection systems 120 of scale die body 151 of decaying, from above-mentioned pre- One group of parameter is selected to carry out CT scan in putting sweep parameter combination, the HU value images of scale die body 151 of entirely being decayed, until Confirmation completes the HU value images in CT detection systems 120 under all preset sweep parameters.

Step 1.3：Only the central region 0 that scanning means 160 is placed on PET detection systems 110 is penetrated by described, penetrate and sweep The rotary shaft 163 of imaging apparatus 160 is alignd with the central shaft of PET detection systems 110；Execution PET scan acquisition is original to meet dataC _A, and record is sent to the source positions of Computerized image processing system 140 by the driving means 164 for penetrating scanning means 160 InformationP _AWith corresponding temporal informationT _A；

Step 1.4：By the decay scale die body 151 and scanning means 160 is penetrated while being placed in PET detection systems 110 Central region 0, decaying the central shaft of scale die body 151 and the central shaft of PET detection systems 110 and penetrates scanning means 160 Rotary shaft 163 align；Execution PET scan acquisition is original to meet dataC _B, and record by the driving dress for penetrating scanning means 160 Put the 164 source positions information for being sent to Computerized image processing system 140P _BAnd temporal informationT _B；

Step 1.5：Meet data using originalC _A、C _BIn temporal information and line source positionP _A、P _BAnd temporal informationT _A、T _B, calculate the coincidence countings of the LOR in the case of the absence and presence of decay scale die body 151 of the gamma photons pair of all directions Exact valueI _AWithI _B；

In the utility model, PET imaging systems include PET detection systems 110, scanning bed 130 and Computer Image Processing System 140.

In the utility model, in step 1.5, in pet imaging systems, the original packet that meets is containing to all directions The line of response of gamma photons pair（LOR）Data and meet Time To Event accordingly, in order to the high accuracy for obtaining each LOR is accorded with Data are closed, relation is met based on the geometry of LOR and line source 161, is met data using originalC _A（C _B）In temporal information and line The position in sourceP _A（P _B）And temporal informationT _A（T _B）, each LOR of calculating is in the case of the absence and presence of decay scale die body 151 The exact value of coincidence countingI _AWithI _B。

Step 1.6：Estimate decay scale die body 151 pairs any thekThe attenuation ratio of 511keV gamma photons pair on bar LORR _k = I _B / I _A；

In the utility model, in step 1.6, as the experimental design for penetrating measurement adopts 161 doses appropriate of line source Amount, and calculatings of the value takes full advantage of LOR and radioactive source generation position meets information, soI _AWithI _BMiddle random counter and The contribution that scattering is counted can be ignored, the scale die body 151 pairs that can be used to estimate exactly to decay any thek511keV on bar LOR The attenuation ratio of gamma photons pairR _k 。

Step 1.7：Due to the measured value of attenuation ratioR _k There is integral relation with linear attenuation coefficient value：INT _k (MU*dx) = log(1 / R _k ), wherein, INT _k Represent to any thekThe linear attenuation factor value of material passed through by bar LOR is along LOR directions On distancedxIntegration, using the CT image HU obtained in HU-MU transformation model MU=TF (HU) and step 1.2 of step 1.1 Be worth to parameterize MU values, and with the actual measurement pad value that obtains in step 1.6R _k Build the multidimensional side under given CT scan parameter Journey INT _k (TF(HU)*dx) = log(1 / R _k ), wherein,kBelong to all LOR through decay scale die body 151；

Step 1.8：The multidimensional equation solution obtained to step 1.7, obtains for all preset CT scan ginsengs in step 1.2 The scale value of several lower HU-MU conversion model parameters；

In the utility model, in step 1.8, the multidimensional equation for being formed is solved using certain method, e.g., can To be entered to the discretization multidimensional equation for obtaining using the known algorithm such as Newton iteration method or Levenberg-Marquardt iterative methods Row is solved, so as to obtain the scale value for HU-MU conversion model parameters under all preset CT scan parameters in step 1.2.

In the utility model, scale value refers to transformation model（That is function）MU=TF（HU）In parameter, according to above-mentioned steps Survey calculation value.

In the utility model, in step 1.8, should also derive other arbitrarily not using methods such as multi-dimensional interpolations The corresponding HU-MU conversion model parameters of any CT scan parameter of the preset CT scan parameter combination being included in step 1.2. In actual operation, due to being limited to actual experimental condition, more it is possible that obtaining under the conditions of specific preset CT scan HU-MU transformational relations, these prerequisites can cover the example of practical clinical more than 95%, and for different from above-mentioned Some specific conditions of prerequisite, it may be necessary to which the value that row interpolation obtains under this group of specified conditions is entered according to above-mentioned scale value, I.e. first scale obtains the transformation model of prerequisite, then interpolation（Known algorithm）Obtain the transformation model under the conditions of other.

Step 1.9：Using the accuracy of the MU values in emulation experiment and clinical scanning image authentication step 1.7；When MU values When accurately, method terminates, and obtains HU-MU conversion model parameters, when MU values are inaccurate, return to step 1.1.

In the utility model, in step 1.9, can be commented using such as Monte-Carlo Simulation and actual clinical picture quality The method that valency is combined is verified to the HU-MU value transformation models for obtaining, it is ensured that the scale value of HU-MU transformational relations meets clinical Require.

In the utility model, it is possible to use certain Monte-Carlo Simulation instrument, such as by International Partnership OpenGATE The Monte-Carlo Simulation software GATE that increases income of exploitation, and the prior information of decay scale die body 151 and PET detection systems 110, if Meter Monte-Carlo Simulation program, so as in the scale die body 151 that obtains decaying main substances of interest to 511keV gamma photons MU values, then, by the MU values that obtain of emulation and based on the HU values generated in HU-MU transformation models scale value and step 1.2 The MU values being converted to relatively determining the accuracy of MU values, to verify the quarter of the linear attenuation coefficient MU values for PET system Degree is accurate enough.

In the utility model, in step 1.9, the clinical trial comprising certain decay scale die body 151 should be also designed, The CT scan and PET scan of multigroup different condition are such as carried out using NEMA/IEC die bodys, and collects multigroup clinical patients scanning View data, is then applied to the HU-MU transformation models for obtaining in correction for attenuation and scatter correction of PET reconstruction images etc., The picture quality and SUV quantitative informations of experiment decay scale die body 151 and clinical patients image are analyzed using known method, it is ensured that The scale value of linear attenuation coefficient MU values does not introduce image artifacts, and the image matter of corresponding decay scale die body 151 and patient The degree of accuracy of amount and SUV quantitative informations is satisfied by clinical requirement, and when MU values are accurate, method terminates, and obtains HU-MU transformation models ginseng Number；If it find that the scale value of MU values is not accurate enough, then need to repeat step 1.1, until confirming that MU values are accurate enough.

In step 1.7, needs carry out structure from correct HU-MU transformation models using the technology of identification to substances of interest Build multidimensional equation.

The multidimensional equation includes the prior substance material of the otherness and decay scale die body 151 using CT image HU values And geological information, the region of interest ROI that carries out of CT images is identified, and region of interest ROI is being calculated along LOR directions DistancedxWhen be modified according to the true form and angle of LOR, so as to obtain accurate discretization integral relation, that is, decay All ROI of scale die body 151 are along anykAll distances on bar LORdx _n With HU values HU of corresponding ROI _n To MU values Conversion TF (HU _n ) and to the distancedx _n Modifying factorf _k,n Product summation relation SUM _{K, n} , INT _k (TF(HU)*dx) = SUM _{K, n} (TF(HU _n ) *dx _n *f _k,n ), wherein,nBelong to all ROI.

In the utility model, in addition to CT scan parameter, HU-MU transformation model MU=TF (HU) is also possible to and concrete thing Matter composition is relevant, and especially, contrast preparation may have an identical HU values but the MU values for differing greatly with tissue, and metal HU values can not linearly expression thing confrontation X-ray decay.Therefore, in step 1.7, need using thing interested to certain The technology of identification of matter, builds multidimensional equation to select correct HU-MU transformation models, on the other hand, in specific implementation process In, need to take certain algorithm to carry out discretization integral relation INT _k , in order to solve to equation, such as, it is possible to use CT The prior substance material and geological information of the otherness and decay scale die body 151 of image HU values, is carried out to CT images interested Area（ROI）Identification, and region of interest ROI is being calculated in the distance on LOR directionsdxWhen will be according to the true form of LOR and angle Degree is modified, and so as to obtain accurate discretization integral relation, that is, all ROI of scale die body 151 of decaying are along any thek All distances on bar LORdx _n With HU values HU of corresponding ROI _n To the conversion TF (HU of MU values _n ) and to the distancedx _n Modifying factor Sonf _k,n Product summation relation SUM _{K, n} , i.e. INT _k (TF(HU)*dx) = SUM _{K, n} (TF(HU _n ) *dx _n *f _k,n )。

In the utility model, ROI（region of interest）, area-of-interest, in machine vision, image procossing, Being sketched the contours of from processed image in modes such as square frame, circle, ellipse, irregular polygons needs region to be processed, referred to as feels emerging Interesting region, ROI.Various operators are commonly used on the machine vision softwares such as Halcon, OpenCV, Matlab（Operator）And letter Count to try to achieve region of interest ROI, and carry out the next step of image and process.In image processing field, area-of-interest (ROI) It is the image-region selected from image, this region is graphical analysis emphasis of interest, draws a circle to approve the region to enter Row is further processed.The target for wanting to read using ROI delineations, it is possible to reduce process time, increases precision.In the utility model, Region of interest is primarily referred to as specific plug-in unit correspondence scope in CT images in aforementioned decay scale die body 151, and such as metal is inserted Part, lung plug-in unit etc..

The utility model is solved in prior art, and bilinearity or three is adopted the correction for attenuation technology based on CT images more Approximate linear function is realizing HU values to the conversion of MU values, and caused this approximate to the MU values that generate for PET image Estimate not accurate enough, meanwhile, the characteristics of being limited to CT and be imaged, CT image HU values can not linearly distinguish contrast preparation and implanted metal The non-human suck tissue such as thing, in turn resulting in corresponding MU values, to calculate deviation larger, easily causes PET image artifact and SUV values The problem of deviation, by by the decay scale die body 151 in the device respectively in CT detection systems 120 and PET detection systems 110 In be scanned, obtain CT reconstruction images, i.e. HU values, and PET penetrate data, according to CT reconstruction images and to HU values to MU values Transformational relation modeling obtains the parametrization MU value of 151 each pixel of decay scale die body, is then based on the parametrization MU value and reality Survey penetrates data and builds multidimensional equation and solve the accurate model parameter for obtaining HU-MU transformational relations, parameter Jing actual measurement PET figures As, after data verification, can be used for clinical PET image reconstruction.The utility model provides the HU-MU transformational relations essence of complete set The apparatus and method of true scale, it is ensured that PET system image quality, thoroughly due to CT continuums and PET in solution clinical practice The linear attenuation coefficient that the intrinsic mismatch of single energy, CT contrast preparation and implanted metal thing etc. cause is estimated higher or low Problem, it is to avoid PET image artifact and quantitative information（Such as SUV values etc.）Deviation, so as to reducing clinical diagnosis misdiagnosis rate and improving Clinical diagnosis diagnosis rate.

Claims (3)

1. a kind of device that PET linear attenuation coefficients are obtained based on CT images, including moveable scanning bed, PET detection systems With CT detection systems, the PET detection systems and CT detection systems be sequentially arranged, the PET detection systems and CT detection systems It is connected to Computerized image processing system, it is characterised in that：Scanning bed the going up detachably is provided with by lifting support structure Decay scale die body, it is described it is scanning bed on be also detachably provided with and penetrate scanning means.

2. it is according to claim 1 it is a kind of based on CT images obtain PET linear attenuation coefficients device, it is characterised in that： The decay scale die body includes filled water container, can inject contrast container and implantable metal object plug-in unit.

3. it is according to claim 1 it is a kind of based on CT images obtain PET linear attenuation coefficients device, it is characterised in that： Described to penetrate the driving means that scanning means includes detachably being located on scanning bed, the driving means are provided with horizontally disposed Rotary shaft, the end vertical of the rotary shaft are provided with support arm, and the support arm is just provided with relative to the end horizontal of rotary shaft Electron emission line source.