CN102697516A - Method for establishing fault contrastographic image display and computer fault contrastographic system - Google Patents
Method for establishing fault contrastographic image display and computer fault contrastographic system Download PDFInfo
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Abstract
The present invention relates to a method for establishing fault contrastographic image display and a computer fault contrastographic system, and the method is realized through the computer fault contrastographic system (1) provided with at least two radiator-detector systems (2,3;4,5). The method has the following steps, utilizing at least one first radiator-detector system (2,3) with a first modulation transmitting function (MTF 1); utilizing at least one second radiator-detector (4,5) to scan patients (P) with the first modulation transmitting function (MTF 1) and a second modulation transmitting function (MTF 2) different from the first modulation transmitting function (MTF 1); generating at least one fault contrastographic image data group (Bges) with at least direct or indirect results (B(MTF 1),B(MTF 2)) obtained by the different modulation transmitting functions; and outputting or storing the at least one fault contrastographic image data group (Bges).
Description
Technical field
The present invention relates at least two irradiator-detector systems of a kind of utilization and set up method and the computer-tomographic system that computed tomography images shows; Wherein utilize at least one first and second irradiator-detector system simultaneously the patient to be scanned, perhaps export at least one computed tomography images demonstration according to the indirect or direct result's generation and the storage of at least twice scanning.
Background technology
Such CT system is known in the notion of multi-source CT system generally.The method of equally, rebuilding the tomographic image data group according to the data of this multi-source CT system is known.
In this CT system and method, the user must determine between definition and noise eclectically up to now.At this, the boundary of the possible selection between definition and noise confirms through measuring system, this measuring system is given in advance optional or predetermined focus size, detector grid and pixel size.In this boundary, regulate definition and corresponding noise through restitution nucleus usually.
For high-contrast, in current prior art, begun the coupling of the strictness between the noise and definition in the image rebuilding method of iteration at least in part.For at the low contrast at noise threshold place and the situation of the low contrast discerned that the typical case occurs in medical science thus, alternative manner does not up to now improve.
Summary of the invention
Therefore; The technical problem that the present invention will solve is; Find at least two irradiator-detector systems of a kind of utilization to set up method and computer-tomographic system that computed tomography images shows, wherein under the situation that low contrast is taken, also can mainly improve the recognizability of detailed structure.
The inventor has realized that; Measurement by the two or more measuring systems with different measuring resolution are carried out can be made up, wherein different Measurement Resolution produce different modulation transfer function (MTF)s (=Modulations-Transfer-Funktion=MTF) or contrast transfer function.Obtain following advantage thus, promptly the corresponding strength of a measuring system compensates the weak place of another measuring system at least in part.So in the image reconstruction that settle the back, complementary information can be bonded to each other, have good low contrast detection probability and high-resolution total view data simultaneously thereby produce.
Preferably, this method can combine the local oscillation frequency of data for projection or view data to divide and weighted blend subsequently, iterative approximation or be fade-in fade-out simply
data for projection or view data are implemented.
Under the situation of using two-tube CT scan device, the probability that the probability that makes up two measuring systems with different physical characteristics is provided and realizes scanning in fact simultaneously (mostly for the patient's) object.At this, be example with different focus size, detector grid or the pixel size of corresponding measuring system.At this, also advise the detector that utilization structure is identical for the pixels with different size, wherein implement a kind of measurement that has no covering and another kind ofly partly cover the measurement of promptly so-called UHR comb through preposition detector element.In addition, also can use different detector kinetics or different detection principles, detector for example counting or integration about noise, linearity and twilight sunset.
Just, the detector system of structure use makes it have two different measuring system MTF in the scope of local oscillation frequency like this.This point especially can be realized through different Measurement Resolution respectively.
For example realizing with little position resolution in the measuring system of high total MTF that algorithm MTF can compensate little position definition, this causes having increased noise.In this additional measurements with higher measuring system MTF following probability is provided: this frequency is not having to represent through algorithm MTF under the too high situation.But this is accompanied by the following defective of measuring technique: produce quantum loss through demarcation strip (Septen), higher electronic device noise and the less tube power deposit under less focus situation.What have advantage thus just is the dose distribution to two of an application measuring system.Total MTF of CT system can be written as the product of algorithm MTF and measuring system MTF at this.The Fourier transformation that algorithm MTF inserts in through the CT convolution kernel with during CT back projection is confirmed.Measuring system MTF comprises the effective width through the fuzzy and x-ray focus of the scanning in the hole of detector channels.For example can be in order to define this notion more accurately referring to publication A.Oppelt, Imaging Systems for Medical Diagnostics, Publicis Erlangen, 2005, the 423 pages.
Describe corresponding to these, the inventor advises a kind ofly setting up the method that computed tomography images shows by the computer-tomographic system with at least two irradiator-detector systems, and it has following method step:
-utilize at least one first irradiator-detector system with first modulation transfer function (MTF), and
-utilize at least one second irradiator-detector system with the second modulation transfer function (MTF) while scan patients different with first modulation transfer function (MTF),
-produce at least one tomographic image data group by the indirect or direct result of at least twice scanning of carrying out with different modulation transfer function (MTF)s,
-export or store this at least one tomographic image data group.
According to first embodiment; Can construct above-described method like this; Make and adopt detector with a plurality of detector elements in order to scan with first modulation transfer function (MTF); Wherein use each detector element to be used to gather ray with its complete radiosensitive measurement face; And adopt at least one to have the detector of a plurality of detector elements in order to scan with at least one second modulation transfer function (MTF), wherein use each detector element to be used to gather ray with radiosensitive measurement face that part covers.
Alternatively; In second embodiment; Also can implement like this according to method of the present invention; Make and adopt detector with a plurality of detector elements in order to scan with first modulation transfer function (MTF); Said a plurality of detector element has and is used to gather first size ray, radiosensitive measurement face, and adopts at least one to have the detector of a plurality of detector elements in order to scan with at least one second modulation transfer function (MTF), and said a plurality of detector elements have and are used to gather other size ray, radiosensitive measurement face.
According to preceding method preferred embodiment, can implement following method step in order to produce at least one tomographic image data group:
-produce projection data set by the measurement data of first modulation transfer function (MTF),
-produce second projection data set by the measurement data of second modulation transfer function (MTF),
-projection data set is divided into the part projection data set of at least two different local oscillation frequencies,
-weighting ground, the part projection data set that mixing is divided specific to local oscillation frequency ground; The component that is wherein drawn by the measurement data of modulation transfer function (MTF) higher when the higher local oscillation frequency obtains higher weight, and obtains higher weight by the component that the measurement data of modulation transfer function (MTF) lower when the lower local oscillation frequency draws.Depend in this embodiment that just local oscillation frequency ground decomposes projection data set, with rear weight ground mixing local oscillation frequency component.
The another kind of scheme of this method relates to the decomposition of depending on local oscillation frequency, and merges the view data that the front rebuilds with rear weight ground.At this, implement following method step in order to produce at least one tomographic image data group:
-rebuild the first tomographic image data group by the projection data set of first modulation transfer function (MTF),
-rebuild second image data set by the projection data set of second modulation transfer function (MTF),
-image data set is divided into the parts of images data set of at least two different local oscillation frequencies,
-weighting ground, the part projection data set that mixing is divided specific to local oscillation frequency ground; The component that is wherein drawn by the measurement data of modulation transfer function (MTF) higher when the higher local oscillation frequency obtains higher weight, and obtains higher weight by the component that the measurement data of modulation transfer function (MTF) lower when the lower local oscillation frequency draws.
According to different once more scheme according to method of the present invention; Suggestion is implemented iterative approximation in order to produce at least one tomographic image data group, wherein input picture is passed through iterative approximation and is similar to final CT image step by step under the situation of having used all measurement data that provide.At this input picture that can advantageous particularly ground will be only draws by the measurement data of detector with higher modulation transfer function (MTF) as " priori " information (English " prior knowledge ").
In the scope of the image rebuilding method of iteration, so-called regularization (regularisierung) is the convergence of method of assuring on the one hand.Its expression is for the key mechanism that possibly reduce picture noise through iterative approximation on the other hand.Two purposes all realize through level and smooth correcting image in each iterative cycles.At this, preferably use so-called " priori " information about the contrast edge of confirming with high-resolution (just corresponding input image data group), so that from real picture structure, distinguish pure noise.For example can under the situation that identifies high-resolution contrast edge, carry out smoothly, and can not lose image detail along this in esse edge in image.
At last according to calculating simple especially embodiment; Also can the projection data set of all detector systems with different modulation transfer function (MTF)s be superposed to a projection data set in order to produce at least one tomographic image data group, and rebuild at least one final tomographic image data group thus.
Replacement as the stack projection data set; In order to produce at least one tomographic image data group; Can also distinguish the reconstructed image data group by the projection data set of detector system, and this image data set that will be drawn by the projection data set of different modulating transfer function is superposed at least one tomographic image data group with different modulating transfer function.
Except according to method of the present invention; The inventor also advises a kind of computer-tomographic system; In this computer-tomographic system, on frame, arrange at least two irradiator-detector systems, to be used for scanography object, particularly patient simultaneously with different measuring resolution.
Particularly advantageously at this be; The computer-tomographic system that the front is described has the computer system that has the memorizer that is used for computer program, and in this memorizer, has stored and when operation, carried out the computer program according to the method step of method of the present invention.
Description of drawings
By accompanying drawing the present invention is described further below, wherein only illustrates in order to understand the necessary characteristic of the present invention.Use following Reference numeral: 1: the double source CT system; 2: the first X-ray tubes; 3: the first detectors; 3.1: scatter-grid; 3.2: detector element; 4: the second X-ray tubes; 5: the second detectors; 5.1: scatter-grid; 5.2: detector element; 6: the frame housing; 7: the contrast agent applicator; 8: patient's bed; 9: system's axle; 10: computer system; B
Ges: final CT image; B
Korr: correcting image; B (MTF (x)): by rebuilding the image data set that R (x) draws; B (x): x image data set in the iteration; FP: forward projection (forward projection); The weighting factor of g (x): P (MTF (x)); IR (1+2): iterative approximation; K (1): edge detection; MTF (x): modulation transfer function (MTF); N: iterations; P: patient; P
Ges: by the projection data set of part projection data set weighted array; P ' is (x): synthetic projection data set; P (MTF (1)): projection data set with first modulation transfer function (MTF); P (MTF (2)): projection data set with second modulation transfer function (MTF); Prg
1-Prg
n: computer program; P (1+2): by the new projection data set of projection data set P (MTF (x)) weighted array; R (1+2): reconstruction procedures; R (x): rebuild through projection data set P (MTF (x)); Reg: regularization term; SBa: first beam; SBb: second beam; TB (H) x: parts of images data set with the high local oscillation frequency that comes from B (MTF (x)); TB (L) x: parts of images data set with the low local oscillation frequency that comes from B (MTF (x)); TP (H) x: part projection data set with high local oscillation frequency of MTF (x); TP (L) x: part projection data set with low local oscillation frequency of MTF (x); Δ: difference image; γ: X ray.
In the accompanying drawing:
Fig. 1 shows the double source CT system;
Fig. 2 shows the cross section of the frame of double source CT system;
Fig. 3 shows the cross section and the details of detector element of the detector of Fig. 2;
Fig. 4 shows data for projection to different MTF to be carried out dividing specific to local oscillation frequency ground, mixes and the sketch map according to method of the present invention of reconstruction with rear weight ground;
Fig. 5 shows the tomographic image data of being made up of the data for projection of different MTF is carried out dividing specific to local oscillation frequency ground and with the blended sketch map according to method of the present invention in rear weight ground;
Fig. 6 shows the sketch map according to method of the present invention of the simple scheme with iterative approximation;
Fig. 7 shows the sketch map according to method of the present invention of iterative approximation;
Fig. 8 shows the sketch map according to of the present invention method of stack by the view data of the data for projection reconstruction of different MFT.
The specific embodiment
Fig. 1 shows the exemplary diagram of double source CT system (=have the CT system of two irradiator-detector systems) 1; This double source CT system has frame housing 6, wherein fixing two irradiator-detector systems that angle is arranged with staggering on this frame that is not shown specifically.Irradiator-detector system is on the one hand by first X-ray tube 2 and the detector 3 that is oppositely arranged with first X-ray tube, form by second X-ray tube 4 with the detector 5 that second X-ray tube is oppositely arranged on the other hand.Two the irradiator-measurement field of detector system scan setting in central circular openings.Can patient P be moved through this measurement field by patient's bed 8 along system's axle 9.Not only can carry out helical scanning in principle also can execution sequence scanning at this point.For the imaging that improves blood vessel or other structure also can be through contrast agent applicator 7 to the patient infusion contrast agent.
According to the present invention; Two detectors 3 and 5 have scattered-out beam and cover; It only sees through directly the ray that arrives from the direction of the irradiator of each positioned opposite on each detector element; Wherein detector element is different by the part that ray covers to different detectors, and realizes different Measurement Resolution and MTF thus.For example also can in detector, adopt additional UHR comb (UHR=ultra high resolution=ultrahigh resolution), this UHR comb (UHR-Kamm) produces the covering of the high percentage ratio (for example＞50%) of detector element.
Implement through the computer system 10 that is attached thereto to the control of CT system 1 with to the analysis of the scanning of patient P, wherein this computer system 10 computer program Prg that had at least one storing therein
1-Prg
nMemorizer.According to the program that the present invention also comprises or store such structure therein, make and carry out different embodiments when it moves in system according to method of the present invention.
The cross section of this frame with two irradiator-detector systems of Fig. 1 has been shown in Fig. 2.First irradiator-detector system is made up of the X-ray tube that sends beam SBa there 2, and this beam SBa aims at the detector 3 of positioned opposite.Detector 3 has scatter-grid 3.1, and this scatter-grid only causes the little covering of detector and has thus than the little Measurement Resolution of second detector but high quantum efficiency.Staggering 90 ° shows second irradiator-detector system, and it has the X-ray tube 4 that can send beam SBb, and this beam SBb aims at the detector 5 of positioned opposite.Detector 5 has the UHR and the scatter-grid 5.1 of combination, has the high covering of detector element, and this causes high Measurement Resolution in less quantum efficiency.Have two irradiator-detector systems thus, it is scan patients P and have different MTF at this simultaneously.
In Fig. 3, show the details of the different coverings of two detectors 3 and 5 detector element once more.On the left side is illustrated in the cross section of the detector 3 in the scope of detector element 3.2 and the scatter-grid 3.1 that is provided with above that.Be capped hardly and can arrive detector plane fully at this from the ray of top arrival.Can find out the relevant details of the detector 5 in the scope at detector element 5.2 and the scatter-grid 5.1 that is provided with above that on adjacent the right.Can be only the less basically part of ray γ be registrated to detector element 5.2 corresponding to the bigger covering of detector element 5.2, but wherein simultaneously the less open plane through detector element 5.2 reach the ratio detection device 3 of detector 5 trickleer many resolution.
Under the simplest situation, the measurement data that obtains from two systems can make up through the image of each generation of being fade-in fade-out simply.Can select said being fade-in fade-out according to structure size and contrast through frequency multiband method.
In the method for reconstructing of iteration, the high-resolution information that obtains from detector can be used as so-called prior information for the data that obtain from two detectors.Thus can be optionally between noise and real contrast information, distinguish.Therefore identical radiation dose with situation under compare the low contrast that this point causes improving with unique measuring system and survey probability.
The diverse ways sketch map that is the basis with above-described measuring method has been shown among Fig. 4 to Fig. 8 below.
Fig. 4 shows first image and produces scheme, wherein utilizes the detector system with different MTF (1) or MTF (2) to produce two projection data set P (MTF (1)) and P (MTF (2)) simultaneously.Then each projection data set is divided into different local oscillation frequency H (=height) and L (=low) dividually, thereby produces four projection data set: P (H) 1, P (L) 1 that obtains from P (MTF (1)) and P (H) 2, the P (L) 2 that obtains from P (MTF (2)).The present different weights of these four projection data set ground is combined as unique projection data set P again
Ges, the wherein outstanding data for projection of introducing with high MTF fine structure information.Then through total projection data set P
GesCarry out final CT image B
GesReconstruction R (1+2), show then or store this CT image B
Ges
Similar method scheme has been shown in Fig. 5; But wherein at first two projection data set P (MTF (1)) and P (MTF (2)) are implemented respectively to rebuild R (1) and R (2) dividually, utilize this reconstruction R (1) and R (2) to calculate image data set B (MTF (1)) and B (MTF (2)) based on different MTF at this.Then these image data set are divided into parts of images data set TB (H) 1, TB (L) 1 and TB (H) 2, the TB (L) 2 with high and low local oscillation frequency respectively.Then parts of images data set different weights ground being united is a new CT image B
Ges, wherein again disproportionately weighting introduce the high-resolution information that the image data set by better MTF draws.
The simple scheme of iterative reconstruction approach has been shown in Fig. 6.At first calculate CT image B (MTF (1)) as input picture through the simple R (1) that rebuilds at this according to projection data set P (MTF (1)).Then through using view data B (MTF (2)) that this input picture is carried out iterative modification iR (1+2), until producing optimum total image B
Ges, this view data B (MTF (2)) comes from the reconstruction R (2) that the second projection data set P (MTF (2)) that from the measurement data of detector with the 2nd MTF, draws is carried out.
Better alternative manner has been shown in Fig. 7.This projection data set that at first will have different resolution P (MTF (1)) and a P (MTF (2)) with weight g (1) and g (2) weighting be combined as new projection data set P (1+2), and the path that illustrates by a dotted line at first reconstructs a CT image data set B (0) and utilizes B (0) initialization B (n) through reconstruction procedures R (1+2).Then a CT image data set is carried out forward projection and draw synthetic projection data set P ' (0), this projection data set P ' (0) compares with primary weighted projection data set P (1+2) in the comparison step Δ.Now difference data is flowed to the computation cycles of iteration.With the difference data that obtains like this (convolution and back projection through weighting for example in step R (1+2); Like it by publication Stierstorfer et al. " Weighted FBP-a simple approximate 3D FBP algorithm for multislice spiral CT with good dose usage for arbitrary pitch "; Phys.Med.Biol.49 (2004) is disclosed that kind (2209-2218)) rebuild, thus produce correcting image B
KorrWith this weighting usually image B (n) addition confirmed of correcting image and front.Therefrom deduct weighting equally usually, the result of regularization.They with the image B of produce improving (n+1).
Concurrently, implement image reconstruction R (1), go up in the image B (1) of rebuilding so subsequently and implement edge detection K (1) according to the projection data set P with high-resolution MTF (1) (MTF (1)).The result of edge detection arrives (known in its function itself) regularization term as " priori " information conveyance.Regularization step purpose is in each iterative step, from image, to deduct pure noise component(s).Especially, in image B (n), obtain to compare the picture noise of minimizing with output image B (0) by nonlinear regularization.For this reason must be from the image information of reality in the scope of regularization burbling noise.Play an important role in this " priori " information.The example of nonlinear regularization is comprise the edge level and smooth, and wherein noise component(s) comprises the level and smooth image B of border land (n) and do not have the difference of level and smooth image B (n) to estimate through formation in iterative step n.At this, actual edge should be known according to " priori " information as far as possible accurately, because otherwise can lose image information.Realized improvement according to the present invention in the additional information that this edge detection K (1) that comes from high-resolution image B (1) draws.
Image B (n+1) according to this improvement recalculates synthetic projection data set P ' (n+1) at this through forward projection, and it is compared with the new projection data set P (1+2) of original definite weighting again in the comparison step Δ and can begin next iteration.At this, the circular symbol with Reference numeral n should be represented the number of iterations carried out.
If in the comparison step Δ, confirm; Difference that synthetic projection data set P ' that image B (n+1) draws confirms between (n+1) is lower than in advance specified value or number of iterations n has reached specified value in advance at the projection data set P of weighting (1+2) and by improving, and the image B (n+1) of the improvement that then will confirm at last is as final total image B
GesOutput.Can in the method for reconstructing of known iteration own, successfully prevent the trickle picture structure of loss during iteration based on " priori " information that obtains now according to the present invention thus through projection data set P (MTF (1)).
At last, Fig. 8 shows the special simple proposal according to method of the present invention, and it is similar to Fig. 5.At this, according to two the projection data set P (MTF (1)) and the P (MTF (2)) of the measurement data that comes from detector respectively with different MTF implement to rebuild R (1) and R (2) dividually and calculate image data set B (MTF (1)) and B (MTF (2)) its thus based on the data of different MTF.Through producing total image B of improving with two image data set that superpose with weight g (1) and g (2) weighting ground
Ges
It is understandable that characteristic of the present invention is not only according to the combination that provides respectively, and also be suitable for, and do not depart from the scope of the present invention according to other combination or when being provided with separately.
Claims (11)
1. one kind by having at least two irradiator-detector systems (2,3; 4,5) computer-tomographic system (1) is set up the method that computed tomography images shows, has following method step:
1.1. utilize at least one first irradiator-detector system (2,3) with first modulation transfer function (MTF) (MTF (1)), and
1.2. utilize at least one second irradiator-detector system (4,5) with second modulation transfer function (MTF) (MTF (2)) the while scan patients (P) different with first modulation transfer function (MTF) (MTF (1)),
1.3. the indirect or direct result (B (MTF (1)), B (MTF (2)), P (MTF (1)), P (MTF (2))) by at least twice scanning of carrying out with different modulation transfer function (MTF)s produces at least one tomographic image data group (B
Ges),
1.4. export or store said at least one tomographic image data group (B
Ges).
2. require 1 described method according to aforesaid right, it is characterized in that,
2.1. adopt detector (3) with a plurality of detector elements (3.2) in order to scan with first modulation transfer function (MTF) (MTF (1)), wherein use each detector element (3.2) being used to gather ray with its complete radiosensitive measurement face, and
2.2. to adopt at least one to have the detector (5) of a plurality of detector elements (5.2) in order scanning, wherein to use each detector element (5.2) to be used to gather ray with the radiosensitive measurement face that partly covers with at least one second modulation transfer function (MTF) (MTF (2)).
3. require 1 described method according to aforesaid right, it is characterized in that,
3.1. adopt the detector (3) with a plurality of detector elements (3.2) in order to scan with first modulation transfer function (MTF) (MTF (1)), the detector element (3.2) that wherein uses first size with radiosensitive measurement face to be being used to gather ray, and
3.2. to adopt at least one to have the detector (5) of a plurality of detector elements (5.2) in order scanning, wherein to use other big or small detector element (5.2) to be used to gather ray with radiosensitive measurement face with at least one second modulation transfer function (MTF) (MTF (2)).
4. require each described method in 1 to 3 according to aforesaid right, it is characterized in that, in order to produce at least one tomographic image data group (B
Ges) the following method step of enforcement:
4.1. the measurement data by first modulation transfer function (MTF) (MTF (1)) produces projection data set (P (MTF (1))),
4.2. the measurement data by second modulation transfer function (MTF) (MTF (2)) produces second projection data set (P (MTF (2))),
4.3. projection data set (P (MTF (1)), P (MTF (2))) is divided into the part projection data set (TP (H) 1, TP (L) 1, TP (H) 2, TP (L) 2) of at least two different local oscillation frequencies,
4.4. weighting ground mixes the part projection data set (TP (H) 1 that is divided specific to local oscillation frequency ground; TP (L) 1; TP (H) 2; TP (L) 2), the component that wherein when higher local oscillation frequency, is drawn by the measurement data of higher modulation transfer function (MTF) (MTF (1)) obtains higher weight, and the component that when lower local oscillation frequency, is drawn by the measurement data of lower modulation transfer function (MTF) (MTF (2)) obtains higher weight.
5. require each described method in 1 to 3 according to aforesaid right, it is characterized in that, in order to produce at least one tomographic image data group (B
Ges) the following method step of enforcement:
5.1. the projection data set (P (MTF (1))) by first modulation transfer function (MTF) (MTF (1)) is rebuild the first tomographic image data group (B (MTF (1))),
5.2. the projection data set (P (MTF (2))) by second modulation transfer function (MTF) (MTF (2)) is rebuild second image data set (B (MTF (2))),
5.3. image data set (B (MTF (1)), B (MTF (2))) is divided into the parts of images data set (T B (H) 1, T B (L) 1, T B (H) 2, T B (L) 2) of at least two different local oscillation frequencies,
5.4. weighting ground mixes part projection data set (the T B (H) 1 that is divided specific to local oscillation frequency ground; T B (L) 1; T B (H) 2; T B (L) 2), the component that wherein when higher local oscillation frequency, is drawn by the measurement data of higher modulation transfer function (MTF) (MTF (1)) obtains higher weight, and the component that when lower local oscillation frequency, is drawn by the measurement data of lower modulation transfer function (MTF) (MTF (2)) obtains higher weight.
6. require each described method in 1 to 3 according to aforesaid right, it is characterized in that, in order to produce at least one tomographic image data group (B
Ges) implement iterative approximation (iR (1+2)), wherein input picture (B (MTF (1))) is approximate step by step to final CT image (B through iterative approximation under the situation of having used all measurement data that provide
Ges).
7. require the method described in 6 according to aforesaid right; It is characterized in that, the input picture that is only drawn by the measurement data of the detector with higher modulation transfer function (MTF) (MTF (1)) is used for the image rebuilding method (iR (1+2)) of iteration as additional " priori " information.
8. require each described method in 1 to 3 according to aforesaid right, it is characterized in that, in order to produce at least one tomographic image data group (B
Ges), the projection data set (P (MTF (1)), P (MTF (2))) that will have all detector systems (3,5) of different modulation transfer function (MTF) (MTF (1), MTF (2)) is superimposed as projection data set (P
Ges), and rebuild at least one final tomographic image data group (B thus
Ges).
9. require each described method in 1 to 3 according to aforesaid right, it is characterized in that, in order to produce at least one tomographic image data group (B
Ges), by detector system (3 with different modulating transfer function (MTF (1), MTF (2)); 5) projection data set (P (MTF (1)); P (MTF (2))) difference reconstructed image data group (B (MTF (1)), B (MTF (2))), and will be by different modulating transfer function (MTF (1); MTF (2)) this image data set that projection data set draws (B (MTF (1)), B (MTF (2))) is superposed at least one tomographic image data group (B
Ges).
10. a computer-tomographic system (1) is characterized in that, in said computer-tomographic system, on frame, arranges at least two irradiator-detector systems (2,3 with different measuring resolution; 4,5), to be used for scanography object, particularly patient (P) simultaneously.
11. require 10 described computer-tomographic systems (1), it is characterized in that setting has the computer program of being used for (Prg according to aforesaid right
1-Prg
n) the computer system (10) of memorizer, and in said memorizer, stored and when operation, carried out computer program according to claim to a method 1 to 9 described method step.
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