CN102258383B - X ray computer tomography device and image processing method - Google Patents

Abstract

The invention provides an X ray computer tomography device used to generate images related to the exercise amount of a specified visceral organ of a to-be-tested body. The X ray computer tomography device includes a data collection unit executing helical scanning of the to-be-tested body and collecting data; a reconstruction unit used to reconstruct a medical image according to the collected projection data; and an image generating unit generating the image expressing the exercise amount of the visceral organ of the to-be-tested body according to an absolute summary which is calculated by calculating the different of the projection data and the relative projection value and using the projection data set composed of the above projection data packaged with a plurality of photographing directions correspondingly and respectively.

Description

X-ray computed tomograohy apparatus and image processing method

The cross reference of related application

The application is based on the Japanese patent application No.2011-098301 that submits in the U.S. Patent application No.12/787166 formerly that submitted on May 25th, 2010, on April 26th, 2011 and to require it be priority, and its full content is by reference in conjunction with in this application.

Technical field

Embodiment described here relates generally to a kind of X-ray computed tomograohy apparatus and image processing method.

Background technology

In recent years, X ray computer tomography (Computed Tomography: below be called " X ray CT ") device has 64～80 x-ray detection device row (below be called " element line ").In the heart CT of this X ray CT device, because can't be whole at same position scanning heart, therefore about the temporary reconstruct window of obtained data selection.For example, when not having the multi-Slice CT device that has for 320 element lines of scanning heart integral body, before the medical imaging of the heart that in fact do not have the pseudo-shadow that caused by heart movement (below be called " without pseudo-shadow ") is reconstructed, in order to select the data for projection corresponding with best heart phase place (below be called " best heart phase place "), need to produce heart phase places (phase place of the motion of heart) figure.

So-called best heart phase place generally is periodic as can be known, is at the heart in the cycle near the Syst end and near the mid point of relaxing period.In these best heart phase places, the motion of heart relatively diminishes.In order to determine best heart phase place, typical method be use with R ripple and R ripple between the method for the relevant electrocardiogram in interval (Electro Cardio Gram: below be called ECG).The selection of the triggering that the data that are used to ECG obtain and best reconstruct window.But ECG only represents the signal of telecommunication of heart, may not represent the state of the machinery relevant with the motion of heart.

And the same with the transmutability of endogenous cycle in the identical subject, best heart phase place finds that as the transmutability that depends between subject the best heart phase place between subject is always challenged.For example, the correct best heart phase place of the heart in the cycle changes at a certain subject and other subject.Therefore, between subject, be not used for determining the single quantitative method of correct best heart phase place.And therefore best heart phase place also changes in identical subject sometimes owing to the such main cause of irregular heart rate that has as arrhythmia.Based on reason as described above, the intrinsic heart phase diagram of subject was produced in order to select the data for projection corresponding with best heart phase place before the medical imaging of reconstruct for the artifact-free heart of specific subject.

In the prior art, suppose the various piece of its tissue of heart with identical action campaign, the motion of heart is different in the various piece of tissue, is complicated, but above-mentioned supposition is oversimplified the complicated character of the motion of heart.Therefore, when selecting best phase place, the motion of heart is minimum, and corresponding view is made as the view of paying no attention to the central position of heart but in fact not having the motion of heart.

In general, with respect to the sweep time of having used the high speed multi-layer spiral CT, the time in order to select best heart phase place after the required scanning (below be called " Selecting phasing time ") accounts for the very large ratio of angiography CT examination of heart.It is when keeping the correctness of the best heart phase place that the medical imaging selecting to be reconstructed uses that being used in the past selected the technology of best heart phase place, attempts making the technology of above-mentioned Selecting phasing time decreased.

A lot of selection technology in the past depend on the zone of medical imaging.Namely, determine best heart phase place according to original data for projection or by the view data of initial data reconstruct.For example, the medical imaging of low resolution is reconstructed in the cycle at the heart after the helical scanning of the heart that has used contrast enhancing program.According to the medical imaging of low resolution, select minimum difference in the phase place of adjacency of the minimum heart movement of expression relevant during.The view data of the low resolution that reconstruct 64 * 64 * 64 voxels are such, but therefore conventional art is not effective owing to the time in the computational process of waste reconstruct.And, in the prior art, exist because the problem that large cone angle causes.And, in the prior art, in the helical scanning of high spacing (amount of feeding of the detector amplitude that namely, rotates a circle for detector, be that the pitch factor is large), there is the problem that can't obtain correct result.

Other conventional art is according to automatic heart Selecting phasing algorithm, makes the technology of Selecting phasing time decreased.In the conventional art, replace image-region, between two the helical scanning raw data sets relevant with next heart phase place, calculate poor absolute value with.Conventional art produces the rate curve of the intensity of the relevant speed of the motion of the heart in the volume of expression and heart integral body.Fig. 1 represents the initial data of the part in the target slice of the axial plane of the space with whole four hearts that represented by horizontal line (right atrium, right ventricle, left atrium, left ventricle).Multilamellar slice CT (Multi-Slice CT: below be called " MSCT ") device has the multiple row detecting element.The initial data corresponding with total time of the position by target slice produces by the interpolation of carrying out the spiral between a plurality of detector columns.By the initial data of spirally interpolation be on identical meeting diagnostic table on time-axis direction continuous dynamic scan data.In addition, the initial data that has different timing information (heart phase place) is obtained by deduct the initial data corresponding with half scanning from a series of initial data that is produced by ECG gate-control signal (timing slip technology).Fig. 1 is illustrated in the initial data of the part on 0%, 10%, 20% the heart phase place.The initial data of these parts and the position of target slice are similarly corresponding with the position of same meeting diagnostic table.But the timing information of the initial data of these parts is different.Similarly, speed about the motion of heart, for the initial data of obtaining with 2% interval, and by obtain poor absolute value with 4% interval and (sum of absolute differences: below be called " SAD "), subtraction is carried out at the interval with 2%.

Above-mentioned conventional art is improved a situation effectively, but can't improve other situation.For example, SAD calculates according to two views corresponding with the phase place that approaches, and rate curve is derived by SAD.And, row after being interpolated in the excessively measured data (namely, measurement data is not considered cone angle) of sinogram data communication device and producing.Therefore, when cone angle and the spiral factor increase, then compare with the measured data of reality, the accuracy of sinogram just reduces.In this case, the SAD based on conventional art can't correctly determine best heart phase place.

The conventional art of previous record is utilized from 0.1 to the 0.3 low spiral factor that changes for helical scanning.Owing to further overlapped significantly in the zone of irradiation by X ray, so these low spiral factors cause the more radiation of multi x-ray.From considering for the comprehensive viewpoint of the peace of subject, with regard to being used for the necessity repeatedly of CT imaging, expect low quantity of radiation level.

Consider the problem of above-mentioned conventional art, other conventional art is the technology according to the static intensity modulating relevant with the technology of the best heart phase place that determine to be used for gate and reconstruct (Step And Shoot: below be called " SAS ") cardiac imaging.That is, in typical SAS data collection, in order to collect simultaneously 64 sections, X-ray tube and X-ray detector for subject be rotated during, top board is motionless a position maintenance.When the uneven so irregular heart bat of the rhythm of the heart produced in data collection, data collection was clapped at the Next common heart and is prepared, and continues in same position.After data collection was through with for certain position, top board advanced predetermined distance to ensuing position for ensuing scanning.For each step, for the radiation that does not partly overlap, top board is moved beyond the distance of the 40mm of the light beam amplitude that probably equals X ray.Replace helical scan data owing to propose the SAS data, so the conventional art reduces the radiation for the X ray of subject, overcome some problems of the cut-out of the major axis relevant with helical scan data.

Above-mentioned conventional art is for the total amount of the motion that determines heart, and utilizes paired sample.Paired sample is as each of the ray of one group of complementation seeing in the original projection data.For the fan-beam data set, one forms right sample by (γ, β) and (γ, β+π+2 γ) definition.At this, γ is corresponding with segment angle and projected angle respectively with β.If γ _mRepresent maximum fan-shaped angle, so minimum cone beam data is collected just at π+2 γ _mRange of views in carry out.Whole set of data is searched for by treating equally whole paired samples.The summation of poor absolute value is by following such calculating.

[several 1]

$\mathrm{\ξ}\left({\mathrm{\β}}_0\right)={\∫}_{-{\mathrm{\γ}}_m}^{{\mathrm{\γ}}_m}{\∫}_{{\mathrm{\β}}_0}^{{\mathrm{\β}}_0+\mathrm{\Π}}|p(\mathrm{\γ},\mathrm{\β})-p(-\mathrm{\γ},\mathrm{\β}+\mathrm{\Π}+2\mathrm{\γ})|\mathrm{d\γd\β}$

At this, ∏＜＜π+2 γ _mIt is the angular range that consistency condition is estimated.ξ (β _m) such amount is the amount that represents the inconsistent degree between the sample of a plurality of combinations of all being evaluated.A plurality of combined samples represent the line integral along same path.According to these, inconsistent degree ξ is the yardstick of the motion of heart.

Above-mentioned conventional art is utilized the sample of the combination in the SAS data in order to make for the radiation reduction of subject and in order to improve the technology of the motion that determines heart.On the other hand, following such shortcoming is arranged in the SAS technology.With respect to the heart cycle be the seriality this point because the SAS technology collects data discontinuously on each position relevant with heart, so can not be taken into the data in seriality heart cycle.After carrying out the data collection on the primary importance, the distance that top board moves regulation till the next position during, do not have the data that are collected.Namely, the SAS data are not collected in the cycle in the scope in identical heart cycle or at the continuous heart.And employed data for projection is in order to adjust projection angle, the overlapping and a part of shortcoming of some in the SAS technology.At last, when using the program of contrast, the discrete delay during the actual data collection is reflected on the effectiveness that makes the contrast program reduces gradually.

Consider above-mentioned shortcoming, the decision that spiral data is expressed for the best heart phase place in the reconstruct is favourable.Utilizing the sample of combination is effectively for the best heart phase place of decision, but the sample of combination is subjected to the SAS data limit, can not be applied to spiral data.

In a word, in the trial of the conventional art of relevant generation heart phase diagram, the situation desired for some shortcoming still exists.These shortcomings have the restriction of effectiveness, pseudo-shadow and helical scanning.In the application to heart CT, improve these shortcomings for generality, heart phase diagram must produce efficiently.The desired phase place of operator should be selected in appropriate time range.Simultaneously, for the pseudo-shadow in the medical imaging that will be reconstructed minimizes, the selection of best heart phase place should correctly be determined.As a result, data for projection should be in order to reflect continuously the motion of heart on the cycle at the heart, and utilizes the obtained data of helical scanning.

[non-patent document 1]

HSIEH，Jiang?et?al.，“Step-and-shoot?Cardiac?Imaging?with?Optimal?Temporal?Gating?and?Reconstruction”，9th?International?Meeting?on?Fully?Three-Dimensional?Image?Reconstruction?in?Radiology?and?Nuclear?Medicine，pages?253-256，(2007).

[non-patent document 2]

MANZKE，R.，et?al.，“Automatic?phase?determination?for?retros?pectively?gated?cardiac?CT”，Medical?Physics?Vol?31，No.12，psges?3345-3362，(2004).

[non-patent document 3]

HOFFMANN，Martin?H.K.，et?al.，“Automatic?determination?of?minimal?cardiac?motion?phases?for?computed?tomography?imaging：initial?experience”，Eur?Radiol，16：365-373，(2006).

[non-patent document 4]

OTA，Takamasa?et?al.，“Clinical?use?fullness?of?automatic?phase?selection?in?coronary?CT?angiography(CTA)”，Medical?Imaging?2007：Physics?of?Medical?Imaging，Proc.of?SPIE?Vol.6510，65102N1-N9，(2007).

Summary of the invention

Purpose is to provide X-ray computed tomograohy apparatus and the image processing method of the generation figure relevant with the quantity of motion of the regulation internal organs of subject.

The X-ray computed tomograohy apparatus that present embodiment relates to is characterized in that, comprising:

By carrying out the helical scanning for subject, collect the data collection section of data;

According to the data for projection based on the data of above-mentioned collection, the reconstructing part of reconstruct medical imaging;

Calculate the poor of above-mentioned data for projection and relative data for projection,

For the projected dataset that is formed by the above-mentioned data for projection in groups corresponding with a plurality of photography directions difference, calculate the absolute value summation of the above-mentioned difference that calculates,

According to above-mentioned absolute value summation, produce the figure generating unit of the momental figure of the internal organs that represent above-mentioned subject.

The image processing method that present embodiment relates to is characterized in that, in X-ray computed tomograohy apparatus, may further comprise the steps:

By carrying out the helical scanning for subject, collect data,

According to the data of above-mentioned collection, produce data for projection,

Calculate the poor of above-mentioned data for projection and relative data for projection,

For the projected dataset that is formed by the above-mentioned data for projection in groups corresponding with a plurality of photography directions difference, calculate the absolute value summation of the above-mentioned difference that calculates,

According to above-mentioned absolute value summation, produce the momental figure of the internal organs of the above-mentioned subject of expression.

X-ray computed tomograohy apparatus and the image processing method of the generation figure relevant with the quantity of motion of the regulation internal organs of subject can be provided.

Description of drawings

Fig. 1 is for representing to have used the figure by the conventional art of the resulting initial data of spiral interpolation.

Fig. 2 is the structure chart of the structure of the multilamellar X-ray computed tomograohy apparatus that relates to of expression present embodiment.

Fig. 3 is the key diagram of ray of one group complementation of many rays about other of the helical scanning that is used for the conceptual illustration present embodiment and relates to.

Fig. 4 has the flow chart for the treatment of step of a part of the helical scan data of minimum heart movement amount for the decision that relates to of expression present embodiment.

The relevant outside drawing of the collection with the spiral data that comprises each bar ray for the PI border that Fig. 5 relates to for the expression present embodiment.

The direct ray from the position radiation of x-ray source that Fig. 6 A relates to for the expression present embodiment be current point ray, with the opposed relative ray of direct ray by the plane graph of PI window summary above from than backward the x-ray source radiation of current some the time.

Fig. 6 B be present embodiment relate to will obtain spiral data during view and the sinogram that represents with top PI window of the relation of passage.

The direct ray from the position radiation of x-ray source that Fig. 7 A relates to for the expression present embodiment be current point ray, with the plane graph of the top PI window summary of the opposed relative ray of direct ray from than forward the x-ray source radiation of current some the time.

Fig. 7 B be present embodiment relate to will obtain spiral data during view and the sinogram that represents with below PI window of the relation of passage.

Fig. 8 is the figure of the position relationship of the X-ray tube on the PI border on the x-y plane that relates to of expression present embodiment and X-ray detector.

Fig. 9 A is the figure of the position relationship of the X-ray tube on the PI border on the x-y plane that relates to of expression present embodiment and X-ray detector.

Fig. 9 B is the X-ray tube S on the PI border on the y-z plane that relates to of presentation graphs 9A ₀Figure with the position relationship of X-ray tube S.

Figure 10 A is the figure that represents with the ECG waveform with respect to the intensity with X ray of view in helical scanning that present embodiment relates to.

Figure 10 B is the figure of the part of expanded view 10A.

Figure 11 is the figure that the inconsistent absolute value summation with respect to the data for projection on the expression PI window of view and relative data for projection that present embodiment relates to shows with X ray intensity.

Figure 12 is the figure that the absolute value summation after the filtering with respect to view (weighted addition) that relates to of Figure 11 represents with the intensity of X ray.

Figure 13 is the figure that the value after filtered absolute value summation is offset is represented with respect to view with the intensity of X ray that Figure 12 relates to.

Figure 14 is that the internal organs quantity of motion with the subject that produces according to the absolute value summation after filtering and the skew that present embodiment relates to is clapped the figure that phase place represents with respect to the heart.

[symbol description]

100-pallet, 101-X ray tube, 102-rotating frame, 103-X ray detection section, 104-data collection section (DAS), 105-non-contact data transfering department, 106-pre-treatment section, 107-rotating part, 108-slip ring, 109-high voltage generating part, 110-system controller, 112-storage part, 114-reconstructing part, 116-expressed portion, 118-selection portion, 200-scan plan assisting system

The specific embodiment

Generally speaking, the X-ray computed tomograohy apparatus about an embodiment has: data collection section, reconstructing part and figure generating unit.Data are collected by carrying out helical scanning for subject by data collection section.The reconstructing part basis is based on the data for projection of the data of above-mentioned collection, reconstruct medical imaging.The figure generating unit is calculated the poor of above-mentioned data for projection and relative data for projection, for by with a plurality of photography directions respectively the projected dataset that consists of of corresponding above-mentioned data for projection in groups calculate the absolute value summation of the above-mentioned difference that calculates, according to above-mentioned absolute value summation, produce the momental figure of the internal organs of the above-mentioned subject of expression.

As the following example relevant with producing motion diagram described later, for the present embodiment of the computer tomography that uses heart (Computed Tomography: below be called " CT ") is selected best phase place and recorded and narrated, but present embodiment is not limited to the CT of heart.Namely, present embodiment also can be applied to heart internal organs in addition.In the present embodiment relevant with heart CT, the phase place of the motion of heart (below be called " heart phase place ") figure produces effectively according to helical scan data.Best heart phase place (below be called " best heart phase place ") is selected in rational time range.Simultaneously, present embodiment correctly determines best heart phase place according to the ray of the X ray of a plurality of complementations described later.The ray of a plurality of complementations is used to produce the index corresponding with the minimum movement of heart.And the ray of a plurality of complementations is used to be chosen in the projected dataset described later that the pseudo-shadow of the minimum in the medical imaging of heart of reconstruct is used.Helical scan data is to have reflected in the scope in the heart cycle that equates or the data of the heart movement in continuous a plurality of heart cycles.Realize application based on the technology of the ray of a plurality of complementations of helical scan data by the ray groups that determines a plurality of complementations three-dimensionally.In order to consider in the scope in the heart cycle that equates or the heart movement in continuous a plurality of heart cycle and determine the ray of one group of complementation.Calculate described later for top (top) ray and the end (bottom) ray or a side absolute value summation described later wherein for the quantity of motion that determines heart.

Below, with reference to accompanying drawing X-ray computed tomograohy apparatus that present embodiment relate to (Computed Tomography: below be called " X ray CT device ") on one side be described on one side.Fig. 2 is the structure chart of the structure of the multilamellar X ray CT device that relates to of expression present embodiment.This multilamellar X ray CT device has pallet 100 and a plurality of unit.Pallet 100 expression side views among Fig. 2.Pallet 100 has X ray test section 103, data collection section (data collection circuit or Data Acquisition system: below be called " DAS ") 104, non-contact data transfering department 105, rotating part 107, the slip ring 108 of X-ray tube 101, rotating frame 102, multiple row or two dimension array type.X-ray tube 101 is installed on the diametical position of cross-section subject S at rotating frame 102 with X ray test section 103.Rotating frame 102 can be supported rotatably around rotating shaft RA.Rotating part 107 turns (rotation) such height with 0.4sec/ makes rotating frame 102 rotations.Rotating part 107 is during making rotating frame 102 rotation, and subject S is in order to carry out helical scanning, and the paper that certainly is illustrated or towards paper moves along rotating shaft.

The multilamellar X ray CT device also has high voltage generating part 109.High voltage generating part 109 is supplied with the tube voltage that is used for producing from X-ray tube 101 X ray via slip ring 108.X ray radiates towards subject S.The hatch region of the circle expression subject of the subject S among Fig. 2.X ray test section 103 is in order to detect the X ray through subject S, and is configured in an opposite side of the X-ray tube of crosscut subject S.A plurality of x-ray detection devices that X ray test section 103 equipments are arranged with two-dimentional shape.At this, single x-ray detection device is consisted of single passage describe.

According to Fig. 2, this multilamellar X ray CT device has a plurality of unit for the treatment of the detection signal of exporting from X ray test section 103.Data collection circuit or DAS104 read two detector columns output signal for each row from X ray test section 103.DAS104 will be transformed to voltage signal from the output signal of each passage.DAS104 amplifies the voltage signal that is transformed.DAS104 becomes digital signal with the voltage signal that is exaggerated.Below, will be called " original projection data " from the data of DAS104 output.X ray test section 103 and DAS104 have the structure of the sum (Total number of Projections Per Rotation: below be called " TPPR ") of the projection of processing every rotation 1 circle of the rotating frame that determines in advance.TPPR is 900TPPR at least, is between 900TPPR and the 1800TPPR, between 900TPPR and the 3600TPPR.

Above-mentioned original projection data is exported to pre-treatment section 106.Above-mentioned original projection data is via non-contact data transfering department 105, is contained in the control part in the outside of pallet 100.Pre-treatment section 106 carries out the specific correction as sensitivity is proofreaied and correct for initial data.Storage part 112 storage is data for projection by the data that are right after before the reconstruction processing that pre-treatment section 106 produces.And so-called data for projection is the set with the corresponding data value of intensity of the X ray that sees through subject.At this, for convenience of description, will be called " projected dataset " by the data for projection in groups of the identical whole passages in the visual angle of probably collecting simultaneously once.And a plurality of projected datasets are corresponding with a plurality of view numbers respectively.In addition, the visual angle is to spend as 0 with the topmost from the vertical circular orbit that makes progress of rotating shaft Z, and in the angle of 360 degree scopes, expression X-ray tube 101 centers on the implication of each position of the circular orbit that rotates centered by aforesaid rotating shaft Z.And, be identified by visual angle, cone angle, passage number for the data for projection of each passage of projected dataset.And projected dataset produces by the execution control of reading relevant with the data for projection in being stored in storage part 112.Storage part 112 is connected with system controller 110, reconstructing part 114, expressed portion 116, input part 115, scan plan assisting system 200, selection portion 118 by data/address bus or control bus.Scan plan assisting system 200 has the function of supporting for to the imaging technique personnel in order to advance scan plan.

Selection portion 118 has various softwares and hardware configuration.Selection portion 118 selected to have the optimal part of data for projection before reconstructing part 114 is processed selecteed data for projection.The selection portion 118 of this multilamellar X ray CT device is in order to reduce in fact the kinetic undesirable pseudo-shadow by heart, selects the part of the data for projection that obtained by helical scanning.Mainly be selection portion 118 for two sides that determine the ray groups that the complementary ray groups in top (top) and the end (bottom) are complementary or wherein either party, and processing data for projection.

Selection portion 118 is calculated the absolute value summation for the difference of the ray of the ray of top described later (top) complementation or the end (bottom) complementation.Selection portion 118 for the absolute value summation, is carried out the skew of filtering and ormal weight in order to consist of motion diagram with appropriate method.At last, selection portion 118 is selected the optimal part of data for projection according to the amount of the absolute value summation minimum that determines.The figure generating unit has the function corresponding with above-mentioned selection portion 118.Namely, the figure generating unit is calculated poor with the opposed relative data for projection of data for projection of data for projection.The figure generating unit is calculated respectively the absolute value summation of the difference that calculates for a plurality of data sets.The figure generating unit produces the momental motion diagram of internal organs of expression subject according to the absolute value summation that calculates.

Reconstructing part 114 is according to projected dataset, the reconstruct medical imaging.Reconstructing part 114 is according to the projected dataset of selecting by selection portion 118, reconstruct medical imaging.

Fig. 3 for the ray of expression in the helical scanning with the concept map of the concept of the ray groups of the complementation of the opposed relative ray of this ray.For simple declaration, do not record and narrate the element of this multilamellar X ray CT device and the heart of subject among Fig. 3.Among Fig. 3, spiral path illustrates with the such ray of X ray three-dimensionally.X among Fig. 3, y, z direction represent respectively with corresponding arrow.The Z direction indication is carried out the direction of helical scanning or has been loaded the direction of the movement of roof of subject.Y-direction and z perpendicular direction, expression visual angle are the direction of 0 degree and 180 degree.Directions X is the direction with y direction and z perpendicular direction.Spiral SPL represents spiral path.Spiral path is during the top board that subject is put in cultivation advances, and x-ray source is during around the subject rotation, the path during by the X-ray view.As with shown in the spiral SPL like that, the such ray of X ray is in the coordinate system that moves with the speed identical with top board by helical scanning, and is not vertical with the z axle.For a plurality of rays of one group of complementation are described, Fig. 3 represents arbitrarily selecteed many rays with many dotted lines.

Among Fig. 3, be projected in any one scope of rotating fully by spiral, represent the ray of the complementation of a group or two groups.The ray of a plurality of complementations is used for the quantity of motion of investigation heart.In Fig. 3, one group of typical complementary ray L ₀With L ₁By spiral projective representation.Complementary ray L ₀With L ₁By defining on π (PI) border that is configured in a plurality of projections.For the PI border, in the explanation of Fig. 5, describe later.The radiogenic position that is used for a plurality of projections is used from the β of (180+ δ) degree ₀With β ₁Represent.The angle how many angle δ separates for expression apart from central ray.If there is not the motion of heart, ray L then ₀With L ₁The thickness of the subject that sees through (ray path) is consistent at the data for projection of obtaining in a spiral manner.

Fig. 4 determines to have the flow chart for the treatment of step of a part of the momental helical scan data of minimum heart for expression.Data for projection uses volumetric scan to obtain (step S10).When obtaining helical scan data, electrocardiogram (Electro Cardio Gram: below be called " ECG ") is for the relevant relative position of peak value of the R ripple that represents to clap with each heart, and is embedded in the data for projection.Under certain situation, X ray is in order to limit the radiation that obtains during the spiral data, according to the information between the peak value of the R ripple of prior setting and illuminated.

Carry out in order to determine best heart phase place afterwards helical scanning during, with the relatively large spiral factor, produce data for projection (step S10).The relatively large spiral factor can be approximated to be 0.2.And the spiral factor is on the size limit of the X-ray detector of reality or in the scope, can also be to be parked in the such spiral factor in PI border namely 0.3.Carry out in the conventional art of above-mentioned record on contrast ground, in helical scanning, for determine best heart phase place require according to the image of data for projection reconstruct low resolution use 0.1 and 0.3 between the little spiral factor.In order to require the little spiral factor, the helical scanning of conventional art is to occur for the radiation of the relatively high X ray of subject and the relative result of long sweep time.By the large spiral factor in the helical scanning, the processing of step S10 makes to obtain be used to sweep time of the data for projection that determines best heart phase place and to the radiation of subject X-ray irradiation and reduces.The radiation of the X ray of subject and the reduction of sweep time are advantages for this situation of protection subject.Obviously the reduction of the quantity of radiation of X ray improves the safety of subject.In the CT photography, improve the comfort level of subject short sweep time.And, owing to during short interval, can more easily suppress the motion of the health of subject, so make the quality improvement of scan-data shorter sweep time.

Calculating is by poor with the opposed relative data for projection of data for projection of the data for projection in the obtained scan-data of step S10.Relatively data for projection be with data for projection corresponding by the data for projection that produces with the such ray of the such opposed relative X ray of ray of X ray.Calculate respectively the absolute value summation (Sum of Absolute Difference: below be called " SAD ") of the difference be calculated for projected dataset (perhaps view (view)).SAD for a view is as following being defined, the absolute value summation of a plurality of passages (channels:ch) relevant with view.

[several 2]

$\mathrm{sum}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\Σ}}\mathrm{abs}\left(\mathrm{diff}\right[\mathrm{ch},\mathrm{view}\left]\right)$

SAD is about relevant content on the PI boundary curve of the ray of the complementation that is comprised of the ray relevant with data for projection and the ray relevant with relative data for projection.The value representation of SAD is because each projected dataset that the motion of heart produces or view inconsistent.Below the ray that the X ray relevant with data for projection is such is called direct ray.And direct ray can also replace with and use primary ray or formal ray.And the ray that the X ray relevant with relative data for projection is such is called " relatively ray ".And, direct ray is used as upper standard of time, be called " current ray ".Relatively ray according to the time relationship of direct ray, can also be called " rear ray " or " front ray ".

By above-mentioned time relationship, SAD is defined as: SAD _TopWith SAD _BottomSAD is current ray at direct ray, when ray is sampled behind current ray and by the spiral data collection relatively, is defined as SAD _TopSimilarly, SAD is current ray at direct ray, when ray is sampled at the front of current ray and by the spiral data collection relatively, is defined as SAD _BottomIn step S20, calculate SAD _TopWith SAD _BottomMiddle at least any one party.In following processing, establish SAD _TopWith SAD _BottomBe assumed to be.

In Fig. 4, use average filter (step 30) for the profile for the SAD of view.This filtering is SAD in calculation procedure S20 _TopWith SAD _BottomIn at least either party the time be essential.SAD represents the motion of heart or the projected dataset that is made of data for projection and relative data for projection inconsistent, still, because direct ray is different with the time relationship of relative ray, so SAD _TopWith SAD _BottomValue inconsistent in a plurality of views.Before in the view of regulation, making the value skew of two SAD, SAD _TopAnd SAD _BottomProfile by using average filter smoothedization.Average filter be for example the regulation filtered amplitude in weighting summation SAD.The filtered amplitude of so-called regulation is 0.5 times number of views of the number of views that for example whenever rotates a circle.

At the filtered SAD of step S30 _TopAnd SAD _BottomData respectively by the skew (step S40).In other words, for the execution of number of views based on the filtered SAD of weighting summation _TopAnd SAD _BottomThe weighted addition curve for to the motion this weighted addition curve of phase matched and be offset ormal weight.Be offset to make and visually confirm on X ray exposes to the sun the border of opening and closing of penetrating for expression SAD _TopAnd SAD _BottomThe SAD of both inconsistent degree of weighted addition curve whether have maximum and become easy.Simultaneously, be offset and make SAD _TopAnd SAD _BottomThe weighted addition curve mutually consistent exactly.In step S40, SAD _TopAnd SAD _BottomThe weighted addition curve when generally correct, minimum SAD is illustrated in the motion of certain view cardiac for minimum.

The data (step S50) of SAD data conversion after the above-mentioned skew for being associated clinically.Accordingly, the SAD data representation that has been transformed is about ratio or from 0 to 100 heart phase place that changes for the heart cycle, the momental figure of heart (below be called " motion diagram ").For example, motion diagram be used to determine with the R crest value of ECG and R crest value between the relevant best heart phase place of the heart in the cycle.The impact that motion diagram is used to select the motion artifacts to the heart that is caused by reconstruct to bring becomes minimum projected dataset.

According to the projected dataset corresponding with the above-mentioned best heart phase place of selecting, according to the restructing algorithm that predetermines, produce the medical imaging (step S60) of heart.For the best image of reconstruct, utilize well the ECG information that is embedded into.ECG information is concentrated from data for projection and is drawn.Derivative ECG information is taken out with respect to the related projected dataset of the reconstruct in the processing of step S60 for according to the clinically related information from step S50, and is stored in the ECG table.The medical imaging of the heart that is reconstructed is substantially without motion artifacts.Simultaneously, because the decision of best heart phase place is performed in the data area, therefore, the utilization of processing is with respect to the conventional art of using the image-region data, excellent in efficiency in the computing.

According to Fig. 4, above-mentioned processing both sides utilize and SAD _TopWith SAD _BottomRelevant data, but in determining best heart phase place, also can only utilize and SAD _TopAnd SAD _BottomAny one party in the relevant data.Which kind of no matter uses, and the processing of above-mentioned steps S30 and step S40 all must be performed for the accurateness of confirming best heart phase place.

Secondly, further specify again each processing from step S10 to step S60 for other accompanying drawing.Fig. 5 is the figure of the expression outward appearance relevant with the collection and treatment (step S10) of spiral data.Fig. 5 is for being used for the figure of expression and related each ray in PI border.Arrow j3 represents to load the direction that the top board of subject moves along rotating shaft RA.X-ray source rotates around rotating shaft RA with spiral path C.X-ray source is in the position y (S of spiral path C ₀) during, each bar ray surface of 5 X ray that radiate from x-ray source is to detector plane (Detector Plane) DP (S ₀) dot.In Fig. 5, central ray A _R0By arrow d ₁Shown such direction scans along the surface of detector plane DP.Simultaneously, contiguous ray A _R1With A _R2Be respectively formed at y (S ₀) on PI border, the top Γ for x-ray source ₁With PI border, bottom Γ ₂At detector plane DP (S ₀) on, PI border, top Γ ₁With PI border, bottom Γ ₂Lay respectively at from the position y (S along the track of each x-ray source ₀) partly rotate on (π)+δ.At this, angle δ is the ray that leaves from central ray and the angle between the central ray.

PI border, top Γ ₁With PI border, bottom Γ ₂Definition PI window.DP (S among Fig. 5 ₀) on hatched example areas represent position y (S for x-ray source ₀) the PI window.The border of PI window is called " PI border ".The PI window is owing to the projection of the track that passes through x-ray source forms, so the size of PI window is relevant with helix speed.If it is large that the spiral factor becomes, the PI window just becomes large so.It should be noted that the spiral factor or top board speed as described below.That is, the PI window need to be parked on the boundary of size of actual detector or in this scope.

Fig. 6 A and Fig. 6 B are expression direct rays when being on the UP PI window, the borderline direct ray of PI and with the opposed relative ray of direct ray between the figure of relation.Shown in the summary plane graph of Fig. 6 A, UP PI window was defined in the following time.From x-ray source S ₀Direct ray be current ray, behind current ray from x-ray source S ₁The ray of sampling is defined when being relative ray.Link S such as using of Fig. 6 A ₀With S ₁Solid line shown in like that, the line on the PI border relevant with direct ray is shared with the line about the PI border of relative ray on UP PI window.The z direction of the movement of roof during the arrow of Fig. 6 A represents to collect along spiral data.At this moment, be DOWN PI window with PI window corresponding to relative ray.Namely, the line on PI border represents UP PI window and DOWN PI window sharing.

Fig. 6 B is the sinogram for above-mentioned UP PI window.Sinogram represent spiral data in collecting a plurality of passages and the relation of a plurality of views.For direct ray, in the gamut of a plurality of passages, view is identical.On the other hand, for relative ray, about the passage this point that changes, view also changes.Namely, view and the passage relevant with relative ray must calculate according to the passage of direct ray.The SAD relevant with view in the processing of this calculating for the step S10 that determines at similar Fig. 4 in the such above-mentioned spiral data of obtained spiral data and being performed.Shown in Fig. 6 B, from based on the passage s on the view V of direct ray to the data for projection of passage e respectively with from the passage e on the view Vs of relative ray to view Ve on the data for projection of passage s corresponding.In addition, passage s is corresponding with the scope of the heart of for example subject with the amplitude of passage e.

For UP PI window, direct ray is current ray, when ray is the ray that is sampled behind current ray in obtaining spiral data relatively, and SAD _TopCalculate as follows with relative ray according to direct ray.

[several 3]

${\mathrm{SAD}}_{\mathrm{top}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\Σ}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{top}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{bot}}[\mathrm{ch},\mathrm{view}\left]\right)$

At this, direct _TopBe the data for projection for the direct ray on the UP PI window.Comp _BottomBe the relative data for projection for the relative ray of DOWN PI window.

As shown in the summary plane graph of Fig. 7 A, DOWN PI window definition is the following time.From x-ray source S ₀Direct ray be current ray, behind the current ray from x-ray source S _-1The ray of sampling is defined when being relative ray.Link S such as using of Fig. 7 A ₀With S _-1Solid line shown in like that, the line on the PI border that the line on the PI border relevant with direct ray is relevant with the relative ray on DOWN PI window is shared.The z direction of the movement of roof during the arrow of Fig. 7 A represents to collect along spiral data.

Fig. 7 B is the sinogram for above-mentioned DOWN PI window.Sinogram represent spiral data in collecting a plurality of passages and the relation of a plurality of views.For direct ray, in the gamut of a plurality of passages, view is identical.On the other hand, for relative ray, about the passage this point that changes, view also changes.Namely, view and the passage relevant with relative ray must calculate according to the passage of direct ray.The SAD relevant with view in the processing of this calculating for the step S10 that determines at similar Fig. 4 in the such above-mentioned spiral data of obtained spiral data and being performed.Shown in Fig. 7 B, from corresponding to the data for projection of the passage s of view Ve with the passage e from the view Vs of relative ray respectively to the data for projection of passage e based on the passage s of the view V of direct ray.

For DOWN PI window, be current ray at direct ray, when ray is the ray that is sampled before current ray in obtaining spiral data relatively, SAD _BottomCalculate as follows with relative ray according to direct ray.

[several 4]

${\mathrm{SAD}}_{\mathrm{bottom}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\Σ}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{bot}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{top}}[\mathrm{ch},\mathrm{view}\left]\right)$

At this, direct _BotBe the data for projection for the direct ray on the DOWN PI window.Comp _TopBe the relative data for projection for the relative light on the UP PI window.

Fig. 8 is the figure on the PI border on the expression x-y plane.Be positioned at S at x-ray source ₀The time, imagine following content.From S ₀The track of the x-ray source that rises of the position primary ray A that has and see through at passage s _R1On the view Vs of opposed relative ray, form PI border, top.From S ₀The track of the x-ray source that rises of position at the elementary line A that has and see through passage e _R2On the view Ve of opposed relative ray, form PI border, below.Up with the PI border of below on, the zone between Vs and the Ve is the shooting visual field (Field of View: below be called " FOV ").Position S ₀And the angle δ β between the S of position satisfies three following conditions when x-ray source is in position S.

[several 5]

Φ ₁≤δβ≤Φ ₂

[several 6]

Φ ₂＝2π-Φ ₁

[several 7]

Φ ₁＝2×cos ^-1(r/R)

At this, as shown in Figure 8, Φ ₁Be ray A _R0With ray A _R4Between angle.Φ ₂Be ray A _R0With ray A _R7Between angle.R is the radius of a circle of expression with the regional corresponding FOV of reconstruct on the x-y plane.R is the radius for the track of x-ray source.All rays that see through from passage S to passage e are necessary for the FOV that covering has radius r.According to above-mentioned condition, the scope of the borderline view of below PI is defined as described below.

[several 8]

V _s＝S ₀-ViewRev+(Ф ₁/2 ^π)×ViewRev

[several 9]

V _e＝V _S+((Φ ₂-Φ ₁)/2 ^π)×ViewRev

At this, view Vs and view Ve for from being positioned at S ₀The such ray (A of X ray of two ends of x-ray source _R1With ray A _R2) corresponding view number.The number of views of ViewRev for whenever rotating a circle.S ₀Be position S ₀On the view number.Ray (the A that the X ray of two ends is such _R1With ray A _R2) join with FOV or reconstruction region.View Vs and view Ve are according to S ₀The view number, represent with a plurality of view numbers.

Similarly, the range of views on top PI border defines as described below.

[several 10]

V _s＝S ₀+(Ф ₁/2 ^π)×ViewRev

[several 11]

V _e＝V _S+((Φ ₂-Φ ₁)/2 ^π)×ViewRev

At this, view Vs and view Ve for from being positioned at S ₀The such ray (A of X ray of two ends of x-ray source _R1With ray A _R2) corresponding view number.The number of views of ViewRev for whenever rotating a circle.S ₀Be position S ₀On the view number.Ray (the A that the X ray of two ends is such _R1With ray A _R2) join with FOV or reconstruction region.View Vs and view Ve are according to S ₀The view number, represent with a plurality of view numbers.

How Fig. 9 A finds out the figure of the borderline ad-hoc location of PI on the x-y plane for expression.How Fig. 9 B finds out the figure of the borderline ad-hoc location of PI on the y-z plane for expression.According to Fig. 9 A, with arc representation with etc. the zone (below be called " detector region ") of X-ray detector corresponding to center represent with thick line.The definition detector region, with each section with detector in (detecting element) from passage number 0ch to the scope of passage number Nch-1 in the passage number Nch that predetermines.X-ray source is in position S ₀The time, be for from position S from the such ray of X ray of position S radiation ₀The relative ray of the ray (direct ray) that the X ray of the correspondence of radiation is such.The position S of x-ray source ₀And the angle δ β between the S of position is associated with angle θ in two following formulas.

[several 12]

R?cos(θ)＝R?sin(δβ/2)

[several 13]

θ＝cos ^-1(sin(δβ/2))

The borderline position S of PI is defined as described below.

[several 14]

h _ch＝Cch+(θ/δγ)

At this, Cch is the passage number at the center of detector.The central passage of detector detects the position S from x-ray source ₀With the X ray of any one party of position S radiation and be X ray by the central point of rotation.h _ChPassage number for detector.With h _ChCorresponding passage pair detects with X ray by the detected X ray angulation of channel C ch θ.δ γ by distinguish a plurality of passages separately fan-shaped angle or the angle of per 1 passage define.

According to Fig. 9 B, x-ray source is in position S ₀The time, on the detector apart from v with apart from δ z by following such method, on the y-z plane, be defined in the z direction.From S ₀To passage h _ChPrimary ray with to the such ray angulation θ of the X ray of channel C ch.Radiation and the position S of the opposed relative ray of above-mentioned primary ray be for screw, distance and S ₀Corresponding z coordinate leaves δ z distance.Computed range v, with determining about passage h for the relevant detector of the view of each passage _ChThe vertical dimension for PI border, top (δ z).Unit apart from v is millimeter.If top board speed CS is mm/rev (speed that the top board that whenever rotates a circle advances), also can be transformed to so the unit of the section of passage number or detector apart from the unit of v.

[several 15]

$\frac{v}{\mathrm{\δz}}=\frac{R}{2R\sin (\mathrm{\δ\β}/2)}$

$=\frac{1}{2\sin (\mathrm{\δ\β}/2)}$

[several 16]

$v=\frac{(\mathrm{\&delta;\&beta;}/2\mathrm{\&pi;})\&times;\mathrm{<figure-callout\; id="2"\; label="CS"\; filenames="HDA0000063571720000071.png,HDA0000063571720000082.png"\; state="\{\{state\}\}">CS</figure-callout>}}{2\sin (\mathrm{\&delta;\&beta;}/2)}$

At this, if the unit take CS as mm/rev defines top board speed, v is exactly mm (millimeter) so.

For the clinical importance of the problem points of understanding above-mentioned record, the figure of the chart of Figure 10 A for showing with the ECG waveform for the intensity of the X ray of view.In the chart of Figure 10 A, also putting down in writing with for the relevant position of the interrupted radiation of the X ray of view.The position relevant with the interrupted radiation of X ray and the peak value of ECG data are determined connectedly.Figure 10 B is the figure of the part of the chart of expanded view 10A during the radiation X ray.Figure 10 B represent the radiation of X ray be ON during the radiation of (below be called " X ray ON ") and X ray be OFF during the group of (below be called " X ray OFF ") reach the scope that surpasses about 1000 views.The view of view when switching from from X ray ON to OFF when switching from X ray OFF to ON brings maximum inconsistent between the data for projection relevant with direct ray and the data for projection relevant with relative ray.The view of view when therefore, switching from from X ray ON to OFF when switching from X ray OFF to ON becomes the preferred labelling of the parameter of momental figure for the heart of proofreading and correct the actual clinical data of expression (below be called " Mmap ") usefulness.

Figure 11 for the expression view with based on the figure of the direct ray on the PI window with the absolute value summation (inconsistent) of relative ray.Amplitude A and AA represent for SAD _TopThe inconsistent zone of maximum.According to direct ray and relative ray, determine SAD for above-mentioned UP PI window _TopThis moment, direct ray was current ray, relatively the ray of ray for being sampled after current ray in obtaining spiral data.Similarly, amplitude B and BB represent for SAD _BottomThe inconsistent zone of maximum.According to direct ray and relative ray, determine SAD for above-mentioned DOWN PI window _BottomThis moment, direct ray was current ray, relatively the ray of ray for being sampled before current ray in obtaining spiral data.The view of view when the graphical presentation of Figure 11 switches from from X ray ON to OFF when switching from X ray OFF to ON.

The view of view when switching from from X ray ON to OFF when switching from X ray OFF to ON brings maximum inconsistent between the data for projection relevant with direct ray and the data for projection relevant with relative ray.The view of view when therefore, switching from from X ray ON to OFF when switching from X ray OFF to ON becomes the preferred labelling of the parameter of momental figure for the heart of proofreading and correct the actual clinical data of expression (below be called " Mmap ") usefulness.For based on the view among the curve of the view of the absolute value summation of the data relevant with the PI border (below be called " PI data boundary difference curve ") and amplitude A, AA, B, the BB-inconsistent curve same meaning.Because these reasons, PI data boundary difference curve is processed in order to form the high Mmap curve of reliability.This processing has by wave filter and averages and make PI data boundary difference curve to be offset.

The value that is used for representing on the chart of wave filter amplitude according to Figure 11 of equalization can be inferred.For example, the approximate average view between maximum inconsistent regional A and the AA poor for be equivalent to each all number of views nearly half.The size of amplitude (number of views that each is all 0.5 times) is for being used for making the good candidate of view-inconsistent curve smoothing.Note this point, when each week is 600 view, use 300 views as filtered amplitude FltL.And filtering also can consist of with weighted curve w as follows.

[several 17]

$\mathrm{Mmap}\left[v\right]=\underset{i=\mathrm{FltL}}{\overset{\mathrm{FltL}}{\mathrm{\&Sigma;}}}\mathrm{SAD}[v-i]\&times;w[i+\mathrm{FltL}]$

At this, v is view.FltL is 0.5 times filtered amplitude based on each all number of views.Weighted curve w is any one party of average function and gaussian weighing function.The SAD of SAD for being defined in advance _TopWith SAD _BottomAny one party.

Figure 12 is expression PI data boundary difference curve or the chart by the filtered weighted addition curve of above-mentioned wave filter.PI data boundary difference curve and the SAD that is weighted behind the addition _TopWith SAD _BottomNear near when switching the view when switching from X ray ON to OFF and from the view from X ray OFF to ON, express in fact more significantly the inconsistent of maximum.But, PI data boundary difference curve and the SAD that is weighted behind the addition _TopWith SAD _BottomNear near when switching the view when switching from X ray ON to OFF and from the view from X ray OFF to ON, also inconsistent.In making the final operation of its consistent operation, with PI data boundary difference curve and the SAD that is weighted behind the addition _TopWith SAD _BottomTo the direction of the view between X ray ON and the X ray OFF or carry out round about the ormal weight skew.The difference of the view when switching for the poor of the view of the view of the inconsistent regional A of maximum when switching from X ray OFF to ON and for the view of the inconsistent regional AA of maximum and from X ray ON to OFF is 150 views at the weighted addition curve.

Figure 13 is the PI data boundary difference curve that is offset of expression or the chart of weighted addition curve.The weighted addition curve offset of Figure 12 150 views.This 150 view is 1/4th corresponding with each all number of views approx.The PI data boundary difference curve and the SAD that have been weighted _TopAnd SAD _BottomBe offset by the method such as following formula definition.

[several 18]

$\mathrm{SAD}\left[\mathrm{view}\right]={\mathrm{SAD}}_{\mathrm{top}}[\mathrm{view}+\frac{\mathrm{ViewRev}}{4}]+{\mathrm{SAD}}_{\mathrm{bottom}}[\mathrm{view}-\frac{\mathrm{ViewRev}}{4}]$

At this, ViewRev is equivalent to each all number of views.

Figure 14 for expression according to by skew, the PI data boundary difference curve and the SAD that have been weighted _TopAnd SAD _BottomThe figure of the motion diagram that produces.PI data boundary difference curve and SAD that motion diagram has represented to be offset, to be weighted _TopAnd SAD _BottomIn the best heart phase place for the inconsistent amount of minimum.Motion diagram represents near near the so best heart phase place of the mid point with relaxing period of Syst end that the motion of heart becomes minimum.In fact in order to pass through corresponding data for projection reconstruct without the medical imaging of motion artifacts, clinically with reference to best heart phase place.

Above-mentioned record is the technology that automatically produces heart phase diagram about having used as an example, determines the record of the embodiment of optimum phase.According to present embodiment, owing to can in data collection, carry out above-mentioned processing, shorten the processing time.And, according to present embodiment, in having the large X-ray computed tomograohy apparatus of multiple row X-ray detector and the spiral factor, can produce correct motion diagram.Present embodiment in fact by improvement reconstruct without the technology of the medical imaging of motion artifacts system and the processing relevant with the technology of selection helical scan data, can be applied to such as other the internal organs such as lung.And the technical thought of present embodiment also can be applied to other medical imaging apparatus.

Although described some embodiment, these embodiment just present in the mode of example, the scope that is not meant to limit the present invention, and in fact, the method and system of novelty described herein can be implemented with various other forms; In addition, can in the situation that does not depart from spirit of the present invention, carry out various omissions, replacement and the change of the form aspect of method and system described herein.Appended claim and equivalent thereof are intended to cover these forms and change, as long as these forms or change drop within the scope and spirit of the present invention.

Claims (24)

1. an X-ray computed tomograohy apparatus is characterized in that, comprising:

By carrying out the helical scanning for subject, collect the data collection section of data;

According to the data for projection based on the data of above-mentioned collection, the reconstructing part of reconstruct medical imaging;

Calculate the poor of above-mentioned data for projection and relative data for projection,

For the projected dataset that is formed by the above-mentioned data for projection in groups corresponding with a plurality of photography directions difference, calculate the absolute value summation of the above-mentioned difference that calculates,

According to above-mentioned absolute value summation, produce the figure generating unit of the momental figure of the internal organs that represent above-mentioned subject,

Above-mentioned relative data for projection be with data for projection corresponding by the data for projection that produces with the such ray of the such opposed relative X ray of ray of X ray.

2. X-ray computed tomograohy apparatus according to claim 1 is characterized in that:

The filtering that above-mentioned figure generating unit puts rules into practice for above-mentioned absolute value summation.

3. X-ray computed tomograohy apparatus according to claim 2 is characterized in that:

Above-mentioned figure generating unit is for the skew of the above-mentioned filtered absolute value summation amount of putting rules into practice.

4. X-ray computed tomograohy apparatus according to claim 1 is characterized in that:

The internal organs of above-mentioned subject are the internal organs that comprise heart.

5. X-ray computed tomograohy apparatus according to claim 1 is characterized in that:

Above-mentioned relative data for projection is the data after above-mentioned data for projection produces.

6. X-ray computed tomograohy apparatus according to claim 5 is characterized in that:

Above-mentioned absolute value summation is passed through

${\mathrm{SAD}}_{\mathrm{top}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\&Sigma;}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{top}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{bot}}[\mathrm{ch},\mathrm{view}\left]\right)$

Calculate SAD _TopBe above-mentioned absolute value summation, direct _TopBe above-mentioned data for projection, comp _BotBe above-mentioned relative data for projection, ch is passage, and view is view.

7. X-ray computed tomograohy apparatus according to claim 1 is characterized in that:

Above-mentioned relative data for projection is the data before above-mentioned data for projection produces.

8. X-ray computed tomograohy apparatus according to claim 7, it is characterized in that: above-mentioned absolute value summation is passed through

${\mathrm{SAD}}_{\mathrm{bottom}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\&Sigma;}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{bot}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{top}}[\mathrm{ch},\mathrm{view}\left]\right)$

Calculate SAD _BottomBe above-mentioned absolute value summation, direct _BotBe above-mentioned data for projection, comp _TopBe above-mentioned relative data for projection, ch is passage, and view is view.

9. X-ray computed tomograohy apparatus according to claim 2 is characterized in that:

Afore mentioned rules be filtered into some in equalization function and the weighting function.

10. X-ray computed tomograohy apparatus according to claim 2 is characterized in that:

Afore mentioned rules be filtered into gaussian weighing function.

11. X-ray computed tomograohy apparatus according to claim 2 is characterized in that:

The filtered amplitude of the filtering of afore mentioned rules is 1/2nd number of views of the number of views that rotates a circle for rotating frame.

12. X-ray computed tomograohy apparatus according to claim 2 is characterized in that:

Above-mentioned figure generating unit is for above-mentioned filtered absolute value summation, carries out 1/4th skew of the number of views that rotates a circle for rotating frame.

13. an image processing method is characterized in that,

In X-ray computed tomograohy apparatus, may further comprise the steps:

By carrying out the helical scanning for subject, collect data,

According to the data of above-mentioned collection, produce data for projection,

Calculate the poor of above-mentioned data for projection and relative data for projection,

For the projected dataset that is formed by the above-mentioned data for projection in groups corresponding with a plurality of photography directions difference, calculate the absolute value summation of the above-mentioned difference that calculates,

According to above-mentioned absolute value summation, produce the momental figure of the internal organs of the above-mentioned subject of expression,

Above-mentioned relative data for projection be with data for projection corresponding by the data for projection that produces with the such ray of the such opposed relative X ray of ray of X ray.

14. image processing method according to claim 13 is characterized in that:

In the process that produces above-mentioned figure,

The filtering that puts rules into practice for above-mentioned absolute value summation,

According to above-mentioned filtered absolute value summation, produce the momental figure of the internal organs of the above-mentioned subject of expression.

15. image processing method according to claim 14 is characterized in that:

In the process that produces above-mentioned figure,

For the skew of the above-mentioned filtered absolute value summation amount of putting rules into practice,

According to the absolute value summation after the above-mentioned skew, produce the momental figure of the internal organs of the above-mentioned subject of expression.

16. image processing method according to claim 13 is characterized in that:

The internal organs of above-mentioned subject are the internal organs that comprise heart.

17. image processing method according to claim 13 is characterized in that:

Above-mentioned relative data for projection is the data after above-mentioned data for projection produces.

18. image processing method according to claim 17 is characterized in that:

Above-mentioned absolute value summation is passed through

${\mathrm{SAD}}_{\mathrm{top}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\&Sigma;}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{top}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{bot}}[\mathrm{ch},\mathrm{view}\left]\right)$

Calculate SAD _TopBe above-mentioned absolute value summation, direct _TopBe above-mentioned data for projection, comp _BotBe above-mentioned relative data for projection, ch is passage, and view is view.

19. image processing method according to claim 13 is characterized in that:

Above-mentioned relative data for projection is the data before above-mentioned data for projection produces.

20. image processing method according to claim 19 is characterized in that:

Above-mentioned absolute value summation is passed through

${\mathrm{SAD}}_{\mathrm{bottom}}\left[\mathrm{view}\right]=\underset{\mathrm{ch}}{\mathrm{\&Sigma;}}\mathrm{abs}\left({\mathrm{direct}}_{\mathrm{bot}}\right[\mathrm{ch},\mathrm{view}]-{\mathrm{comp}}_{\mathrm{top}}[\mathrm{ch},\mathrm{view}\left]\right)$

Calculate SAD _BottomBe above-mentioned absolute value summation, direct _BotBe above-mentioned data for projection, comp _TopBe above-mentioned relative data for projection, ch is passage, and view is view.

21. image processing method according to claim 14 is characterized in that:

Carry out some in equalization function and the weighting function of being filtered into of afore mentioned rules.

22. image processing method according to claim 14 is characterized in that:

Carry out the gaussian weighing function that is filtered into of afore mentioned rules.

23. image processing method according to claim 14 is characterized in that:

The filtered amplitude of the filtering of afore mentioned rules is 1/2nd number of views of the number of views that rotates a circle for rotating frame.

24. image processing method according to claim 14 is characterized in that:

In producing the process of above-mentioned figure, for above-mentioned filtered absolute value summation, carry out 1/4th skew of the number of views that rotates a circle for rotating frame.

Images