CN1247155C - Optimized CT protocol - Google Patents
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Abstract
立体计算机X射线断层造影(CT)系统具有通过开关装置(6)被连接到模数转换器(ADCs)的区域检测器(3)。通过操纵开关装置，空间分辨率能被调节。这可以改变轴向覆盖、扫描时间及视图数。
A stereoscopic computed tomography (CT) system has an area detector (3) connected to analog-to-digital converters (ADCs) through switching means (6). By manipulating the switching device, the spatial resolution can be adjusted. This can vary axial coverage, scan time, and number of views.
Description
Background of invention
The present invention relates to computer topography (CT) and, more particularly, relate to instrument and the method used in three-dimensional CT scan system, in order to optimize the scanning operation that is used for special-purpose, this scanning system makes resolution, sweep speed, axially cover the parameter that (by imaging patient's scope) and other and area detector interrelate can be changed.
Computer topography (CT) is a kind of technology, it comprises usually makes the patient bear X ray, obtain the digitized X ray projection data of a patient body part, and handle and the digitized X ray projection data of backprojection to generate the image that is displayed on subsequently on the CT system display monitor.The CT system generally comprises stand, platform, X-ray tube, X-ray detector array, computer and display monitor.Computer send order to the controller of stand so that controller goes to rotate X-ray tube and/or detector array by specific slewing rate.
In third generation CT system, between detector array and X-ray tube, generate relatively rotating around patient body.Relatively rotate when being generated when this, computer is handled by the performed data acquisition of X-ray tube and detector array to obtain digitized X-ray radiography.Computer is subsequently by carrying out algorithm for reconstructing processing and the digitized X-ray radiography data of back projection and the CT image of rebuilding being presented on the display monitor.
The many CT system that is using now uses independent delegation detector in stand, it is commonly called the line array detector element.Advanced CT system uses two line array to four detectors to constitute multi-row detector.Though two kinds of detector arrangement can both be used with the helical form scan protocol, multi-row detector is convenient to patient's scanning, owing to can be scanned in the short period of time by the pitch patient's who increases the CT system specified axial covering.Pitch is generally defined as rotating the displacement of support patient table between one-period and the ratio of detector spacings at stand.For example, pitch is 1 to refer to and rotate the quantity that patient table moves between one-period at the CT of CT system stand and equal detector spacings.
The use of multi-row detector is more revolutionary scan protocol, it the scanning of whole organ can be finished in once the holding one's breath of patient (thereby promptly the scan period patient can restrain his/her breathing makes the patient be reduced to the minimum time period by the motion of imaging part).
Up-to-date improvement is the digitized detector array in the X-ray radiography field, is commonly referred to as area detector, appearance.Area detector is to have the rectangular grid that the dimension magnitude is the single detector element (pixel) of hundreds of micron.Can there be several thousand pixels on the every limit of rectangle detector grid.When area detector was used in the CT system, the CT system was commonly referred to as three-dimensional CT system, or the CVT system.This area detector technology is substituting X-ray film and is being used for planar X-ray radiography in the sophisticated equipment of clinical setting, thereby make the simple two-dimensional image of patient in certain orientation of X-ray tube and detector, it passes patient's decay corresponding to X-ray beam.Therefore these equipment are migrated " no film " X-ray radiography field.
A significant advantage of area detector technology is that it can shorten sweep time.In the once rotation of stand, the axial covering of complete organ can be obtained.On the contrary, the CT system of application multirow needs repeatedly rotating of stand to go to realize identical axial covering.Generally recognizing in the art, using the area detector Technology Need to obtain extra data to generate mathematical complete data set.Yet these extra data can be generally known as search sweep at patient's single linear scanning, in be acquired.Usually, patient's search sweep generally begins and guarantees that the patient is obtained before being placed correctly under in the VCT scanner at axial scan.This suitable axial covering that has also guaranteed the patient is scanned.Therefore might use the area detector technology to reduce sweep time of patient one or two magnitude usually.
Because detector element has the dimension or the resolution of qualification, characteristics of CT image are its spatial resolution, and it is commonly referred to as the face intrinsic resolution of image.The influence of examined device resolution of face intrinsic resolution and CT imaging system actual geometric configuration.Use the face intrinsic resolution of the CT reconstruction of the collected data of multi-row detector technology to be about 0.5 millimeter.Suppose and do not use overscan technique to go to improve effectively resolution, axial resolution can be up to 1.25mm.Have can be less than the resolution of a magnitude of its multirow homologue for the single detector element in area detector array.Therefore, also can be than from be calculated a little magnitude of reconstruction with the collected data of multi-row detector technology from the face intrinsic resolution of the CT data of rebuilding with the collected data of area detector technology.
Because the single detector element is normally quadrate in detector array, the volume of rebuilding has isotropic volume elements resolution, i.e. the face intrinsic resolution rebuild of CT be complementary with the axial resolution of reconstruction (the limited dimension that is effective slice thickness of CT reconstruction and detector is directly relevant).In other words, because detector element is quadrate, the face intrinsic resolution and the slice thickness of single axial CT image equate in the volume of rebuilding.This characteristics of data reconstruction make the data can be by reformatting producing the sagitta of arc and the coronal view of data, and these views are rebuilt and in loss resolution aspect the reformatting data in several axial planes.
Usually, detector wire or multirow is not quadrate.The slice thickness of image reconstruction or axial resolution are generally greater than the face intrinsic resolution.If observe patient's axial image, this normally preferably is orientated, and then resolution is identical on two dimensions.Yet by reformatting data in the cross section sagitta of arc or coronal, the observer will notice that level and vertical resolution are unequal in image.The positive impact of isotropism volume elements resolution still remains to be seen clearly the data that the X-ray radiography that is obtained from the application region detector technologies is rebuild, because clinical boundary did not recognize the ability and the adaptability of high definition picture in the past as yet.
Medical CT system now reckons without such as sweep time, axially the coordination between the parameter such as covering and/or spatial resolution can be utilized to optimize the mode that regional detection technique is used.Be the interval during the patient bears X ray sweep time.Axially covering is scope in the covering of being throwed on by the patient of x-ray source in imaging during the CT examination.Spatial resolution is the dimension of pixel unit in image reconstruction and is used to indicate in the face here and/or axial resolution.The dimension of the examined device element of spatial resolution also is subjected to the influence of the geometry of CT stand.
Therefore, in order to select the optimization pattern of area detector technical operation for given purposes, exist for the application region detector technologies and consider the method for these parameter coordinations and the needs of instrument.Be described in detail as following, by considering these coordinations and passing through the operational mode of selection corresponding to optimum coordination, can be optimised for given purposes scanning operation.
Summary of the invention
The invention provides the method and the instrument that in stereo computer x-ray tomography radiography (VCT) system, use.The VCT system comprises x-ray source, area detector, at the stand that between object and x-ray source and area detector, produces relative rotation during specific sweep time.The VCT system also comprises the data acquisition assembly and reads electronic equipment.When the specific axis that turns to X ray at stand appeared at state on the object to covering, x-ray source was incident upon X ray on the object.Detector element response projection X ray thereon generates the signal of telecommunication.The switching device that is connected with detector element is handled selectively so which to select be output and be sent to some analog-digital converters (ADCs) that convert them to digital signal by the signal of telecommunication that some detector element generated of detector from detector element in any specific time.By master cock device selectively in such a way, the spatial resolution of image reconstruction can be changed and be regulated selectively by the number that makes the detector element signal that is joined together and is sent to ADCs.Other sweep parameters can be changed equally, such as, for example, axially covering, sweep time and when stand rotates by number of views that area detector obtained.Coordinate by between in these sweep parameters some, patient's scanning can be optimised for given imaging purposes.
To become apparent from following description, accompanying drawing and claim those those skilled in the art that these and other characteristics of the present invention and advantage.
The accompanying drawing summary
Fig. 1 is the block diagram of explanation according to preferred embodiment three-dimensional CT scan of the present invention system.
Fig. 2 is the flow chart of explanation according to a kind of scheme method of the present invention.
Fig. 3 is the flow chart of explanation according to another kind of scheme method of the present invention.
Fig. 4 is the flow chart of explanation according to another scheme method of the present invention.
Detailed Description Of The Invention
In order to prove some advantage of the present invention, some prior art will here come into question so that clearly illustrate that various characteristics of the present invention.For example, the single slice CT scans device is used the line detector array provides the collimator that is prepended to the patient so that can be obtained along the axial variable slice thickness of patient.Yet, in this scanning device, generally be not configurable towards resolution.The multi-film CT scanning device make up a few line shape detector acquisition in the X ray projection data at each visual angle of stand to rebuild several sections.The great majority of these systems comprise special circuit so that the user can change axial slices thickness.And, can not change the face intrinsic resolution in these systems usually.
By in three-dimensional CT (VCT) scanning device, using the area detector technology, might optimize the data acquisition rules for specific imaging purposes.More precisely, for example, coordination can patient scan time, face intrinsic resolution, axial resolution, azimuth sampling, and by the attainable covering of VCT scanning device between selected or be determined.Up to the present these coordinations also are not implemented.Therefore, still undiscovered and be implemented as the whole benefits that will be familiar with the area detector technology that those skilled in the art understand.
The zone detection technique provides high resolution 2 d (2D) line grating of detector element, because the dimension of detector is normally symmetric, it usually can be for the usefulness of isotropism image reconstruction.Although best detection device element is symmetric, be unnecessary for this requirement of the present invention.
As mentioned above, in existing C T detector technologies, might stipulate or change axial slices thickness, use detector array wire or multirow to go to obtain the X ray projection data at this thickness.Yet the face intrinsic resolution generally is uncontrollable.Therefore, can not generate the three-dimensional (3D) with isotropism volume elements dimension rebuilds.These technology have several restrictions, and the most significant is that the reformatting of the planar reconstruction data of the coronal and sagitta of arc in the patient has the resolution of variation in the 2D reformatting data.Use the surface of the 3D data set of rebuilding and the restriction that three-dimensional rendering technique also all is subjected to the data person's character.
By in the VCT system, using area detector, compare with the operational monolithic or the multi-disc scanning device that exist now, might in obviously short interval, on patient's big zone, obtain the projection data of X ray.The spatial resolution of area detector technology can than by what a magnitude that detector technologies obtained wire or multirow.In addition, area detector has the detector element of how many row than the multi-disc detector, and in most applications, two to three magnitudes are more gone.Higher resolution and the more row of detector element has many advantages in area detector, but as discussed in more detail below, because the detector element of greater number also causes making in each detector cell signal digitalized remarkable difficulty in area detector under each visual angle of stand in given sweep time.
The area array detector technologies is used the storage diode technology usually so that each detector element can sequentially be read.Each detector element compile be mapped to that particular element on the relevant signal of X ray energy and store this information.According to the present invention, the signal in detector element utilizes multiplexer and analog-digital converter (ADCs) sequentially to be digitized then.This structure has reduced the complexity of reading electronic equipment of data collecting system 6 significantly, and this data collecting system is required signal digitalized in whole detector array.By using analog switch to change the parts number that is multiplexed to specific ADC, might be to the resolution of specific purposes configuration digital detector.
For example, by selectively several groups of detector element (variable resolution) being linked together, reduced the readout time for the view picture of each projection data of being obtained by data collecting system 6 (variable sweep time), this is for the imaging purposes, for example, patient or organ movement are focus there, may be necessary.In addition, if X-ray beam is suitable collimation, at each visual angle of stand only some detector array by x-ray bombardment (that is, variable covering).Might change resolution, sweep time and/or axial covering of scanning device to meet the target of specific scan protocol.Yet, describe method of the present invention and instrument can effective mode before, will be provided with reference to figure 1 the generality discussion of VCT of the present invention system.
Fig. 1 is the block diagram that is suitable for realizing the three-dimensional CT scan system of method of the present invention and instrument.Solid CT scan system will come into question in the application aspect reconstruction patient's the anatomical components image according to it, be not limited to any specific object Cheng Xiang, as being familiar with those personnel understood of present technique field though it will be appreciated that the present invention, the present invention also can be used for industrial processes.In addition, the present invention also is not limited to Medical CT equipment, and the geometry of x-ray source and detector was held fixed industrial system when scan period, object was rotated and be included in.
In three-dimensional CT scan system, stand is around object, such as the patient, rotates and projection data is acquired.The running of the three-dimensional CT scan of computer 1 control system.When mentioning the rotation of stand here, this phrase is to be used for representing the rotation of X-ray tube 2 and/or the rotation of detector 3, the preferably high-resolution area detector of detector.X-ray tube 2 and area detector 3 are all comprised by stand.Controller 4A and 4B are handled by three-dimensional CT scan component computer 1 and are connected respectively to X-ray tube 2 and to detector 3. Controller 4A and 4B cause suitable the relatively rotating of waiting to pass to X-ray tube 2 and/or detector 3, and special-purpose controller is unwanted.Independent controller part can be used to rotational stand.Also note that in order to realize method computer 1 manipulation of the present invention in the scanning of image time, the change of picture resolution and/or axially covering aspect.
Also note that the present invention is not limited to for finishing any specific computer that data acquisition and processing (DAP) task of the present invention is used.Term " computer " here be used for representing any can finish the present invention must task calculating or the machine of computation be used.Therefore, being used the computer of finishing control algolithm 10 of the present invention can be any machine that can finish required task.
Several imaging schemes will come into question now with benefit and the adaptability of demonstration according to numeric area detector technologies of the present invention.If, for example, patient's high resolution scanning uses whole detector panel obtained, and this operator scheme will need the slower scanning speed of VCT system, because the signal demand in each detector element is digitized by analog-digital converter (ADC) in the 2D array.Best, a plurality of ADCs will be used to this purpose so that from signal digitalized required time of each detector element with length within reason.
Axial covering by the restriction X-ray beam may reduce sweep time, i.e. required time of the target area of scan patients is because less signal demand is digitized.Suppose that axial covering is identical, then by several detector element multiplexes are entered ADCs, can further reduce patient's sweep time.Yet, also reduced in the resolution of the projection data that this situation obtained, because the output of several detector element is by multiplex together and output to ADCs.
Also may be by reduce the sweep time that azimuthal sampling (number of the X ray projection that is promptly obtained by minimizing) reduces the patient when the patient is scanned.In other words, the number of views that is obtained when the patient rotates when stand is reduced.This method causes the image quality problem.Certainly, the decline of image quality aspect is can be received in some imaging purposes, but not in other respects.
For given sweep time, may adjust spatial resolution for patient's axial covering.In other words, may in given sweep time, reduce axially to cover and obtain high-resolution data.On the other hand, might in the axial covering of broad, obtain high-resolution data.In these situations, can be held constant sweep time, owing to treat that the significant figure of digitized passage remains unchanged.Substantially and need as many signal to be kept constant so that treat digitized signal sum by multiplex together.This scheme is by the flowcharting that is shown in Fig. 2.As indicated in square frame 12,, as indicated in square frame 13, for the required resolution of specific sweep time and purposes with axially cover and just can be determined, can and axially make coordinated mode between the covering in resolution and be gone through below in case sweep time is chosen.
In case it is these variablees are chosen and/or be determined, as indicated in square frame 14, rebuilt by the projection data that the VCT system obtains.Such projection data can rebuilt mode be well known in the art.Understood as being familiar with those skilled in the art, the various algorithms that are suitable for finishing reconstruction are known, and for example, the Feldkamp algorithm is suitable for this purpose and by known in the art.
Following scheme is described some basic coordination, and they can be constant at the specific image parameter of maintenance, do not made when promptly not changing specific parameter.
(1) for selected (that is, immovable) sweep time
When keeping constant sweep time, axially covering can be sacrificed, or, in other words, be reduced, help increasing spatial resolution.On the contrary, spatial resolution can be sacrificed, or, in other words, be reduced, to help increasing axial covering.
As alternative method, can be held constant sweep time when increasing spatial resolution and/or axially covering, and will require the number of views in that stand is obtained when the patient rotates to be reduced but do like this.And can keep constant sweep time when stand rotates around the patient and increases the number of views of being obtained, is reduced requiring spatial resolution and/or axially covering but do like this.
(2) for constant axial covering
Constant axial covering can be held when sweep time and spatial resolution are increased.Otherwise when sweep time and spatial resolution were reduced, constant axial covering also can be held.
As alternative method, axial covering can keep constant when increasing spatial resolution and/or reducing sweep time, is reduced when stand centers on the number of views of being obtained when the patient rotates but do requirement like this.In addition, as long as spatial resolution is reduced and/or be increased sweep time, axially covering can keep constant when the number of views that stand rotates and obtained around the patient is increased.
(3) for constant spatial resolution
Constant spatial resolution can be held when be increased sweep time.In this case, axially covering also can be increased and spatial resolution is changed.On the contrary, if be reduced sweep time for given spatial resolution, axially covering can be reduced so that keep constant by the digitized detector signal of ADC.
As alternative method, spatial resolution can be held constant when increase axially covers and/or reduces sweep time, is reduced but do the number of views that will require in that stand is obtained like this when the patient rotates.In addition, as long as axial covering is reduced and/or be increased sweep time, it is constant that spatial resolution can be held when the number of views that stand rotates and obtained around the patient is increased.
Basic conception of the present invention for convenience of explanation and for simplicity will suppose that hereinafter the number of views of being obtained is held constant when stand rotates.Yet descried as energy from top three kinds of schemes, the visual angle number that is obtained when stand rotates is to make another parameter that can be taken into account in the above-mentioned coordination decision.
Scheme (1) briefly shows if sweep time is chosen and it is variable not to be, as indicated in square frame 12, spatial resolution can be increased, but axially covers and must be reduced in order to obtain data in identical interval.On the other hand, if be held constant sweep time, or for some reason is not variable (for example, scanning has the zone of motion, such as lung), axially covering can be increased, and will reduce spatial resolution but do like this.Either way will be useful in some cases.This scheme is briefly represented by Fig. 2.Fig. 2 shows that for selected sweep time and constant projected view number, axially covering and spatial resolution should be determined, as indicated in square frame 13.For constant sweep time, spatial resolution and axial the covering each other in inverse ratio.Therefore, any one is changed in these variablees, constantly must make suitable coordination between them in order to keep sweep time.These decisions can be operated the VCT system or by the computer of carrying out control algolithm, such as computer 1, make by operator.In case suitable coordination is made, image is just rebuilt by determined resolution, as indicated in square frame 14.
Scheme (2) shows that briefly this can realize that it can cause the increase of spatial resolution by increasing sweep time, has more time to remove the signal of read detector element owing to read electronic equipment if wish to use specific axial covering.Otherwise, can obtain specific axial resolution by reducing sweep time, this causes more detector element signal to be multiplexed to identical ADCs.This equally also causes the visual obtained of low resolution.This scheme is briefly represented by Fig. 3.As shown in FIG. 3, if specific axial covering is chosen, as indicated in square frame 18, resolution and sweep time or by computer or chosen or be determined by system operators, as indicated in square frame 19, coordination can be made the scan protocol special-purpose is realized wanted in resolution with between sweep time.In case projection data is digitized, image is just rebuilt, as indicated in square frame 20.
Scheme (3) briefly shows if selected spatial resolution does not change or for certain reason is held constant, sweep time and axial covering can be increased and spatial resolution is changed.Yet,, must carefully consider to be chosen in the suitable increase of axial covering aspect if be increased specific quantity sweep time.Substantially, when be increased sweep time, the quantity that axial covering can be increased was that the amount that be increased by sweep time limits.On the contrary, be increased, must be increased suitable quantity sweep time in order to keep selected spatial resolution if axially cover.
On the other hand, sweep time and the axial both of covering can be reduced and not make spatial resolution to change.In this case, by reducing axial covering and sweep time, specific resolution can be held.This means that less zone was scanned with short a period of time, this can cause obtaining to resemble the same resolution of the previous case.Yet in order to keep constant spatial resolution, the minimizing of sweep time will restrictive axial cover the quantity that is reduced.Equally, in order to keep constant spatial resolution, axial reducing of covering also will be limited the quantity that is reduced sweep time.
This scheme is briefly by the flowcharting of Fig. 4.Spatial resolution is at first selected, as indicated in square frame 23.Sweep time and axial covering are determined according to desired space resolution then or are chosen, as indicated in square frame 24, therefore, the resolution of wanting in order to reach is coordinated and can be made between sweep time and axial the covering according to scan protocol of wanting and specific purposes.In case projection data is by the ADCs digitized, image is just rebuilt, as indicated in square frame 25.
In these schemes each is used in specific purposes.Yet, as from above scheme, seeing, in most of the cases, for some parameter of operational mode of optimizing for special-purpose must be adjusted to support other parameters.Following example will help to illustrate these coordinate how to be determined and to be optimized to realize best sweeping scheme for specific purposes.
X-ray beam can be known to obtain certain mode that axially covers by collimation.If go for bigger axial covering (for example, obtaining the image of whole chest in the time of equal number), then bigger slice thickness should be obtained when be held constant sweep time.Because more data is obtained owing to have more data to be acquired during identical a period of time, the reading electronic equipment and when more detector element signal is sent to ADCs, they must be mixed of data collecting system 6.This is sent to ADCs equally corresponding to lower resolution together because more detector element signal is combined in.Therefore, the collimator (not shown) is opened obtaining this bigger axial covering, but spatial resolution is sacrificed.
On the contrary, if the low resolution image of chest discloses some object be concerned about that more carefully be checked, so collimator should narrow down the high-resolution of being concerned about the zone to obtain image also reduction to patient's accumulated dose.Because less data can be acquired, when the detector element signal is multiplexed to ADCs, read signal combination that electronic equipment will as much together.Therefore, signal multiplex together is controlled to obtain the resolution wanted, and coaxial covering is the same.Can not need be increased sweep time, because axially covering is reduced, this is consistent with scheme (1).
Be important to note that the clinical driver that is used for specific purposes will pre-determine the correct pattern of VCT system operation.Be important to note that for constant sweep time, might adjust spatial resolution for axially covering, and vice-versa.The representative instance of this system benefits is such as to the fluoroscopical purposes of pulmonary tuberculosis.In fluoroscopy, scanning for the first time spreads all over whole chest with low resolution.This requires bigger axial covering, and owing to wishes that during once holding one's breath to patient scan, be reduced needs sweep time.This two aspects factor all can reduce resolution.
If tuberculosis is examined out, cross section (the axial covering that the be reduced) high resolution scanning thin for chest can be implemented.In order to obtain high-resolution picture, can increase sweep time so that the output of less detector element is multiplexed to specific ADCs together, promptly reading electronic equipment has the more time to go to read the output of each detector element.Yet, if departing from the channel that is increased, the axial covering that is reduced reads, can reduce further sweep time in this case.In other words, perhaps may reduce sweep time simultaneously and increase resolution, as long as axially cover the reducing on digitization time that causes more than departing from the required temporal increase of digitized high-resolution data by reducing.
As another example, helical form scanning can be implemented, and it can keep certain sweep time and reduce axial covering.This can make resolution increase equally, has the more time to go read detector element signal (the detector element signal demand that is lesser amt is multiplexed to identical ADCs) owing to read electronic equipment.
Therefore, the present invention makes the sweep speed can be for resolution and/or axially cover and be adjusted.And resolution can be for sweep speed and/or is axially covered and be adjusted.Similarly, axially covering can be adjusted for sweep speed and/or resolution.Up to the present these coordinations, are not realized as yet and are not implemented in the field of VCT technology.Therefore, the benefit of area detector technology is not approved fully or has been given play to their whole advantages.Should be noted that when the phrase spatial resolution is referred this is used in the presentation surface and/or axial resolution here.
Should be noted that the present invention comes into question according to some embodiment.Yet the present invention is not limited to these embodiments.For example, three schemes that come into question, and do not mean that the coordination mode that all comprises above-mentioned parameter, these modes can be used to obtain the suitable operational mode of VCT system.It is for basic conception of the present invention and the mode for realizing that suitable scan protocol basic parameter can be coordinated are described that these schemes come into question.In addition, coordinate to be not limited to scan protocol, that is, they are applicable to axial scan (patient table is not moved) and helical form scan protocol during sweep phase.Those those skilled in the art that will appreciate that these basic conceptions can be utilized and be extrapolated to reach the mode of other area detector scan protocol, and these rules are useful for specific purposes.
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| US12939799P | 1999-04-15 | 1999-04-15 | |
| US60/129397 | 1999-04-15 |
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| CN1247155C true CN1247155C (en) | 2006-03-29 |
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| JP4172753B2 (en) * | 2002-04-03 | 2008-10-29 | 東芝医用システムエンジニアリング株式会社 | X-ray imaging device |
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| JPS61143041A (en) * | 1984-11-27 | 1986-06-30 | 横河メディカルシステム株式会社 | X-ray ct apparatus |
| JPS628740A (en) * | 1985-07-04 | 1987-01-16 | 株式会社東芝 | Tomographic examination apparatus |
| JPS6429788A (en) * | 1987-07-24 | 1989-01-31 | Toshiba Corp | Radiation detector |
| JPS6443236A (en) * | 1987-08-12 | 1989-02-15 | Toshiba Corp | Ct scanner |
| JPS6449994A (en) * | 1987-08-20 | 1989-02-27 | Toshiba Corp | Radiation detector |
| US5485493A (en) * | 1988-10-20 | 1996-01-16 | Picker International, Inc. | Multiple detector ring spiral scanner with relatively adjustable helical paths |
| US5142286A (en) * | 1990-10-01 | 1992-08-25 | General Electric Company | Read-out photodiodes using sigma-delta oversampled analog-to-digital converters |
| JPH06233757A (en) * | 1993-02-12 | 1994-08-23 | Hitachi Ltd | Three-dimensional photographing device |
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| US5430784A (en) * | 1994-02-28 | 1995-07-04 | General Electric Company | Computerized tomography imaging using multi-slice detector with selectable slice thickness |
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| US6047040A (en) * | 1994-07-29 | 2000-04-04 | Hu; Hui | Detector signal integration in volumetric CT scanner detector arrays |
| JPH08299321A (en) * | 1995-04-27 | 1996-11-19 | Shimadzu Corp | X-ray computed tomography(ct) device |
| JPH09308627A (en) * | 1996-05-23 | 1997-12-02 | Ge Yokogawa Medical Syst Ltd | Method and device for picking up image |
| JPH09313478A (en) * | 1996-06-03 | 1997-12-09 | Ge Yokogawa Medical Syst Ltd | Image reconstructing method and radiations ct device |
| US5802134A (en) * | 1997-04-09 | 1998-09-01 | Analogic Corporation | Nutating slice CT image reconstruction apparatus and method |
| JPH10314162A (en) * | 1997-05-15 | 1998-12-02 | Ge Yokogawa Medical Syst Ltd | Radiation tomography and its device |
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| AU4240500A (en) | 2000-11-02 |
| JP2002541897A (en) | 2002-12-10 |
| DE10081368T1 (en) | 2001-06-28 |
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