CN1736335A - X-ray computed tomographic equipment - Google Patents
X-ray computed tomographic equipment Download PDFInfo
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- CN1736335A CN1736335A CNA2005101037396A CN200510103739A CN1736335A CN 1736335 A CN1736335 A CN 1736335A CN A2005101037396 A CNA2005101037396 A CN A2005101037396A CN 200510103739 A CN200510103739 A CN 200510103739A CN 1736335 A CN1736335 A CN 1736335A
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Abstract
The invention provides an X-ray computed tomography apparatus which comprises a first detection system with a first X-ray tube for irradiating a subject to be examined with X-rays at a first irradiation dose and a first X-ray detector for detecting X-rays transmitted through the subject; and a second detection system with a second X-ray tube for irradiating the subject with X-rays at a second irradiation dose higher than the first irradiation dose and a second X-ray detector for detecting X-rays transmitted through the subject; and a moving mechanism configured to move at least one of the first and the second detection systems in a body axis direction of the subject.
Description
The application is that October 8, application number in 2002 are 02147227.0, denomination of invention is divided an application for the application of " X ray computed tomographic equipment ".
Technical field
The present invention relates to a kind of X ray computed tomographic equipment with function of the abnormal operation supervision such as paradoxical discharge in the X-ray tube unit etc.
Background technology
As known, a kind of by it with at a high speed can be continuously and seamlessly obtain the helical scanning of the data for projection in the broader region that will check object, by being synchronized with the movement, i.e. continuous rotation of X-ray tube, multi-channel type X-ray detector etc. and the motion realization of going up the table top of the bed of placing object thereof.
Most of current suitable X ray computed tomographic equipments have according to the state of the supervision X-ray tubes such as mode of operation of tube voltage, tube current, filament heating current, inner tube temperature, coolant pump and stop to comprise the interlock function of the scan operation of needed x-ray bombardment.
Routinely, when activating this interlock function so that stopping x-ray bombardment, seek and eliminate reason.In addition, if the operator provides errorless clearly instruction, then stop to comprise the entire scan operation of x-ray bombardment.
A kind of like this interlock function is very easily, and is being a kind of indispensable function aspect the improvement safety.On the other hand, must usually start scanning once more comprehensively.In contrast medium inspection etc., for example, the CT value is one of most important information to the variation of time.If stop scanning on the way by interlock function, then almost lose the contrast reinforced effects.Reason for this reason, inject contrast degree medium is to scan again from beginning once more.In above helical scanning, even stop to begin scan operation constantly, because the variation of the posture of the object that will check during stopping sweep time etc. also may obtain discontinuous data from scanning.Also under such a case, must scan again from beginning.
Usually, X-ray tube is equipped with a diaphragm apparatus, and is designed to change slice thickness by regulating membranous aperture.Owing to determine slice thickness, must before obtaining, data determine membrane pore size and the degree of freedom that after data obtain, does not have slice thickness to change basically according to the membrane pore size width.Therefore, have the tomographic image of different slice thicknesses if desired, then the operator must multiple scanning when changing the membrane pore size width.Jpn.Pat.Appln.KOKAI publication No.9-215688 discloses a kind of by using the twofold detection device to obtain to have the technology of different slice thicknesses simultaneously.Yet, locate to obtain data at different slice position (different section centers).Therefore, in the time need having the tomographic image of different slice thicknesses at identical slice position place, also must multiple scanning.
Recently, developed a kind of semiconductor detector that directly X ray that sees through the object that will check is converted to electric charge, and x-ray irradiation dose, promptly exposure dose often reduces with the improvement of detector sensitivity.Yet the reducing of exposure dose has its limit.When exposure dose becomes a scheduled volume or more hour, density resolution significantly reduces, cause to guarantee the picture quality that is suitable for diagnosing.
When the contrast media imaging, importantly when flowing into imaging region, the contrast medium that injects the object that will check scans (helical scanning in this case; Monitor scans and main scanning are distinguished out).Reason for this reason must monitor flowing of contrast medium in the position upstream of imaging region.In other words, in the multiple scanning continuously of monitored position place, and re-construct in real time and show the tomographic image data by generating data for projection.
The operator observes this tomographic image, and imports the triggering that is used for main scanning when timing interested blood vessel dye levels increases to a certain degree.When receiving this triggering, equipment stops monitor scans, and table top is moved to scanning starting position in imaging region.In addition, equipment etc. are ready to use in the foundation from the condition of scanning of operator's main scanning (X ray launching condition, screw pitch etc.), switch the output voltage of high-voltage generating unit according to setting up condition, and preheat filament.After finishing this preparation, equipment is by providing tube voltage and triggering the actual main scanning that starts.As mentioned above, before reality starts main scanning, need the table top motion, set up, reach to launch and prepare.
The time of these action needs is not short.Reason for this reason begins to flow into suitable timing in the imaging region with respect to the contrast medium, and main scanning may be to postpone beginning.In order to prevent a kind of like this situation, consider the operating time, when the blood vessel dye levels is not too high, must import the triggering that is used for main scanning.This timing need to determine skilled knowledge and experience.
Summary of the invention
Even one object of the present invention is abnormal case and occurs also allowing the X ray computed tomographic equipment to continue scanning.
Another object of the present invention is, allows the X ray computed tomographic equipment to obtain data about the section with different slice thicknesses at identical slice position place in single pass.
Another purpose of the present invention is, reduces light exposure and guarantee high image quality simultaneously in the X ray computed tomographic equipment.
Another purpose of the present invention is, by shortening from wherein the contrast media injections being removed the needed time to the monitor scans of main scanning, reduces to start with main scanning the deviation of timing.
According to an aspect of the present invention, provide a kind of X ray computed tomographic equipment, comprising: one first data snooping system comprises one first X-ray tube and one first X-ray detector; One second data snooping system comprises one second X-ray tube and one second X-ray detector; Reach one and re-construct the unit, re-construct and one first corresponding first view data of slice thickness according to output, and re-construct and corresponding second view data of second slice thickness littler than first slice thickness according to output from second X-ray detector from first X-ray detector.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: one first detection system, be configured to have first X-ray tube of the object that will check with x-ray bombardment, restriction from the dispersion angle of the X ray of first X-ray tube and can change aperture the first X ray collimator, and a detection from first X-ray detector emission of first X-ray tube and that see through the X ray of object; One second detection system, be configured to have second X-ray tube of the object that will check with x-ray bombardment, restriction from the dispersion angle of the X ray of second X-ray tube and can change aperture the second X ray collimator, and a detection from second X-ray detector emission of second X-ray tube and that see through the X ray of object; A scan control unit is configured to the aperture of the second X ray collimator is arranged to lower than the aperture of the first X ray collimator; Reach one and re-construct the unit, be configured to re-construct view data according to data for projection that obtains by first X-ray detector and the data for projection that obtains by second X-ray detector.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: a plurality of detection systems, each be configured to have the X-ray tube of the object that will check with x-ray bombardment, restriction from the dispersion angle of the X ray of X-ray tube and can change aperture the X ray collimator, and a detection from the X-ray detector X-ray tube emission and that see through the X ray of object; A scan control unit is configured to the aperture of the X ray collimator of at least one described a plurality of data snooping system is arranged to littler than the aperture of the X ray collimator of remainder data detection system; Reach one and re-construct the unit, be configured to re-construct view data according to the data for projection that obtains by described a plurality of X-ray detectors.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: a plurality of detection systems, each be configured to have the X-ray tube of the object that will check with x-ray bombardment, a restriction X-ray tube X ray dispersion angle and can change aperture the X ray collimator, and a detection from the X-ray detector X-ray tube emission and that see through the X ray of object, the X ray collimator of at least one of described a plurality of data snooping system has the little aperture of aperture than the X ray collimator of remainder data detection system; Reach one and re-construct the unit, be configured to re-construct view data according to the data for projection that obtains by described a plurality of X-ray detectors.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: a plurality of detection systems, each be configured to have the X-ray tube of the object that will check with x-ray bombardment, a restriction X-ray tube X ray dispersion angle and can change aperture the X ray collimator, and a detection from the X-ray detector X-ray tube emission and that see through the X ray of object, the aperture of described a plurality of X ray collimators can be provided with independently; Reach one and re-construct the unit, be configured to re-construct view data according to the data for projection that obtains by described a plurality of X-ray detectors.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: one first detection system has first X-ray tube of the object that will check with x-ray bombardment with first exposure dose and first X-ray detector that detection sees through the X ray of object; One second detection system has one to see through second X-ray detector of the X ray of object with second X-ray tube of x-ray bombardment object and detection than high second exposure dose of first exposure dose; Reach a motion, be configured at least one of the first and second data snooping systems that on the body axis direction of object, move.
According to a further aspect in the invention, a kind of X ray computed tomographic equipment is provided, comprise: a plurality of data snooping system, its each have the X-ray tube of the object that will check with x-ray bombardment and an X-ray detector that detection sees through the X ray of object; One re-constructs the unit, is configured to re-construct view data in real time according at least one the output of detector from described a plurality of data snooping system; And control unit, be configured to monitor contrast medium the flowing in the main scanning zone be expelled in the object, and when the contrast MEDIA FLOW is become owner of in the scanning area, make another data snooping system of described a plurality of data snooping system begin the data acquisition according to view data.
Other purpose of the present invention and advantage are narrated in description subsequently, and will be obvious by describing part, perhaps can learn by enforcement of the present invention.Can realize and obtain objects and advantages of the present invention by means of means that hereinafter particularly point out and combination.
Description of drawings
Incorporate and constitute the description of drawings current most preferred embodiment of the present invention of this description part into, and, be used for explaining principle of the present invention with the detailed description of above general description that provides and most preferred embodiment given below.
Fig. 1 is a block chart, and expression is according to the major part of the X ray computed tomographic equipment of first embodiment of the invention;
Fig. 2 is an axonometric chart, is illustrated in the layout of first and second detectors among Fig. 1;
Fig. 3 is a curve chart, and expression is according to the track of this embodiment first and second X-ray tubes in helical scanning;
Fig. 4 is a curve chart, is used for explaining a kind of scanning continuous function in helical scanning according to this embodiment;
Fig. 5 is a curve chart, is used for explaining in detail according to a kind of scanning continuous function of this embodiment in helical scanning;
Fig. 6 is a curve chart, is used for explaining the scanning continuous function in single section scanning according to this embodiment;
Fig. 7 is a curve chart, is used for explaining in detail the scanning continuous function in single section scanning according to this embodiment;
Fig. 8 is a block chart, and expression is according to the layout of the major part of the X ray computed tomographic equipment of second embodiment of the invention;
Fig. 9 is a view, the layout of presentation graphs 8 mesohigh generating units;
Figure 10 A and 10B are views, the slice thickness of the first and second data snooping systems in the presentation graphs 8;
Figure 11 A and 11B are the plan views of first and second X-ray detectors among Fig. 8;
Figure 12 is a view, is illustrated in the primary importance pattern position of the first and second data snooping systems among Fig. 8;
Figure 13 is a view, is illustrated in the second position pattern position of the first and second data snooping systems among Fig. 8;
Figure 14 A and 14B are views, are illustrated in the slice thickness of the first and second data snooping systems in the improvement of present embodiment;
Figure 15 A and 15B are the plan views of first and second X-ray detectors among Figure 14 B and the 14B;
Figure 16 A and 16B are views, the slice thickness of the first and second data snooping systems during the another kind that is illustrated in this embodiment improves;
Figure 17 is a view, is illustrated in the position of the first and second data snooping systems among Figure 16 A and the 16B;
Figure 18 is a block chart, and expression is according to the layout of the major part of the X ray computed tomographic equipment of third embodiment of the invention;
Figure 19 is a view, is illustrated in the aperture of first and second collimators among Figure 18;
Figure 20 is a curve chart, the track of first and second X-ray tubes among expression Figure 18;
Figure 21 is a view, schematically illustrates the data for projection that is obtained respectively by the first and second data snooping systems in Figure 18;
Figure 22 is a view, represent a kind of wherein when interesting areas exists on turning cylinder under rotating the aperture and the immovable in this embodiment state of aperture location of the second X ray collimator;
Figure 23 is a view, represent a kind of wherein when the position that interesting areas is being left turning cylinder exists under rotating the aperture of the second X ray collimator and the state that aperture location changes in this embodiment;
Figure 24 is a block chart, and expression is according to the layout of the major part of the X ray computed tomographic equipment of fourth embodiment of the invention;
Figure 25 is a flow chart, and expression is by first control operation of true preparation control unit in Figure 24;
Figure 26 is a view, and expression is when table top distance between first and second data snooping system in Figure 24 when forwards moving upward;
Figure 27 is a view, expression distance between first and second data snooping system in Figure 24 when table top in the opposite direction moves;
Figure 28 is a flow chart, and expression is by second control operation of true preparation control unit in Figure 24;
Figure 29 is a curve chart, is illustrated in second control operation among Figure 28 with respect to the tube voltage of time in first and second X-ray tubes to change and changed by the movement velocity of the table top of a bed driver element motion;
Figure 30 is a flow chart, and expression is by the 3rd control operation of true preparation control unit in Figure 24;
Figure 31 is a curve chart, be illustrated in the 3rd control operation among Figure 30 the variation of the meansigma methods of the CT value of pixel in the area-of-interest in first tomographic image that obtains by monitor scans with respect to the time, the tube voltage in first and second X-ray tubes with the variation of bed driver element with respect to the time;
Figure 32 A is a flow chart, the first half of the 4th control operation of the true preparation control unit of expression by in Figure 24;
Figure 32 B is a flow chart, the second half of the 4th control operation of the true preparation control unit of expression by in Figure 24; And
Figure 33 is a curve chart, be used for explaining in the 4th control operation of a kind of calculating in Figure 32 B between monitor scans starts to main scanning time delay DLT1 method, be illustrated in of the variation of the meansigma methods of the CT value in the first and second data snooping systems with respect to the time.
The specific embodiment
View is with reference to the accompanying drawings explained the X ray computed tomographic equipment of the most preferred embodiment according to the present invention in more detail.Notice that the X ray computed tomographic equipment comprises various types of equipment, for example wherein the rotation/rotational type equipment that rotates around the object that will check together of X-ray tube and X-ray detector and a plurality of detecting elements of wherein arranging with loop type are fixed and static/rotation equipment that X-ray tube rotates around the object that will check only.The present invention can be applied to any type.In this case, will illustrate that current is the rotation/rotational type equipment of main flow.
In order to re-construct single section tomographic image data, need with around the corresponding about 360 ° projection data set of object one phase inversion that will check, perhaps in half scan method, need one group of 210 ° to 240 ° data for projection.The present invention can be applied to any of these schemes.In this case, with explanation be preceding a kind of scheme that the projection data set by about 360 ° of general scheme re-constructs a tomographic image.
As the mechanism that incident X-rays is converted to electric charge, following technology is a main flow: a kind ofly X ray is converted to light and light is converted to the indirect conversion type of electric charge and use by the motion to electrode of the right generation in the electricity-hole of X ray in quasiconductor and electron-hole pair by the photo-electric conversion element such as photodiode by the phosphorus such as scintillator, be photoconductive phenomenon, direct translation type.As a kind of X ray detecting element, can use any of these schemes.In this case, will illustrate last type, i.e. the indirect conversion type.
Tomographic image is that the section with certain thickness tissue shows; The thickness of tissue slice is called slice thickness.X ray is radially dispersed from the focus of X-ray tube, passes the object that will check, and arrives X-ray detector.Therefore, the thickness of X ray increases with the increase of the distance of the focus of leaving X-ray tube.Routinely, the thickness of the X ray on the center of rotation axis is defined as slice thickness.According to custom, in this case, the thickness of the X ray on the center of rotation axis is called slice thickness.This is applicable to the width of detecting element on slice direction.In expression " detecting element has and certain corresponding sensitivity width of slice thickness ", the sensitivity width is in fact greater than slice thickness.More particularly, according to the ratio of distance between x-ray focus and center of rotation axis and the distance between x-ray focus and detecting element, this sensitivity width is designed to greater than slice thickness.
(first embodiment)
Fig. 1 represents the major part according to the X ray computed tomographic equipment of this embodiment.X ray computed tomographic equipment according to this embodiment comprises a scanning stand 1001, computer installation 1002, reaches bed 1003.Scanning stand 1001 is constituent elements that are used for obtaining about the data for projection of the object that will check.This data for projection is loaded in the computer installation 1002, and is subjected to the processing such as image re-constructs.Object lie in the bed table top on the time, be inserted into scanning stand 1001 imaging region in.Bed 1003 is equipped with one and is used for along the table top moving cell 1032 of its longitudinal axis (almost being equivalent to the body axis that keeps flat object in bed) motion table top 1031.Computer installation 1002 comprise a central control unit 1021, one through data/control bus 1022 be connected to preprocessor 1023 on the central control unit 1021, bench board 1027, data memory element 1028, one re-construct unit 1024, image-display units 1025, and channel failure monitor unit 1026.
Scanning stand 1001 is multitube types, promptly has a plurality of data snooping system, and each comprises an x-ray tube component and X-ray detector, is installed on the annular rotational stand.In this case, scanning stand 1001 will be described as two cast stands.As shown in Figure 2, one first data snooping system 1011 has first x-ray tube component 1110 and first X-ray detector 1113 that is installed on the rotational stand.In the second data snooping system 1012, one second x-ray tube component 1120 and second X-ray detector 1123 facing to it are installed on the rotational stand, intersect at the central axial line of the first data snooping system 1011 at the first pivot center RA place thereby the central axial line of the second data snooping system 1012 (is assumed to 90 ° here) at a predetermined angle.The rotational stand that the second data snooping system 1012 is installed on it can be identical, perhaps different with it with the stand of the installation first data snooping system 1011 on it.
The second data snooping system 1012 is so supported by a moving cell 1016, thereby can move along pivot center RA.This makes might be arranged on a position to the position of the second data snooping system 1012 on pivot center RA (hereinafter being called the Z position), and wherein it overlaps with the Z position of the first data snooping system 1011, perhaps leaves an one preset distance.In this embodiment, in helical scanning, a preset distance is removed backward from the Z position of the first data snooping system 1011 in the Z position of the second data snooping system 1012.In monolithic scanning, the Z position of the second data snooping system 1012 is arranged on position identical with the Z position of the first data snooping system 1011 or position much at one.
First x-ray tube component 1110 comprises an X-ray tube 1111, reference detector 1112, and the peripheral cell (not shown) such as cooling system, wave filter and barrier film.Similarly, second x-ray tube component 1120 comprises an X-ray tube 1121, reference detector 1122, and the peripheral cell (not shown) such as cooling system, wave filter and barrier film.Reference detector 1112 and 1122 is arranged in the wherein incident position, peripheral part of X ray.Inefficacy monitor unit 1015 according to from the output of reference detector 1112 and 1122 or from the variation of its output by the reducing suddenly of x-ray irradiation dose, detecting x-ray pipe 1111 and 1121 mode of operation, the i.e. appearance of paradoxical discharge (electric arc).Note, can replace with pick off according to other scheme reference detector 1112 and 1122.If use the pipe flow table, the monitor unit 1015 that then lost efficacy is by the unexpected increase energy detecting x-ray pipe 1111 of pipe flow and 1121 mode of operation.
A high-voltage generating unit 1013 is applied to tube voltage on x-ray tube component 1110 and 1120, supplies with the filament heating current to it, and control cooling system, wave filter and membranous operation.Except that control to high-voltage generating unit 1013, the desired all operations control of scanning is responsible in scan control unit 1014, comprise the Z position of the motion of rotation, the table top 1031 of rotational stand, the second data snooping system 1012 by moving cell 1016 variation, and obtain the processing of unit 1114 and 1124 by data, for example, signal I/O operation and amplification/quantification.
Scan control unit 1014 is connected on the inefficacy monitor unit 1015.When inefficacy monitor unit 1015 detects the generation of paradoxical discharge in X-ray tube 1111 or 1121, scan control unit 1014 is with respect to high-voltage generating unit 1013, stops to be applied to tube voltage on the X-ray tube 1111 or 1121 that paradoxical discharge wherein taken place and to stop to supply with a needed processing of filament heating current.If x-ray tube component 1110 and 1120 is equipped with the X ray shutter, then when tube voltage applies or be independent of its closed shutter.
Suppose paradoxical discharge takes place.Knownly restart voltage after interrupting a short time period when applying when voltage applies, abnormal operation usually recovers.Scan control unit 1014 has a kind of like this auto restore facility.In other words, scan control unit 1014 stops tube voltage being applied on X-ray tube 1111 or 1121, wherein lost efficacy and took place, and carry out after stopping, restarting tube voltage with respect to high-voltage generating unit 1013 and apply a needed processing of predetermined amount of time.
The data (being called raw data) that obtained unit 1114 and 1124 acquisitions by data allow continuous slip ring (not shown) of rotating to send to the preprocessor 1023 of computer installation 1002 through one.Preprocessor 1023 is proofreaied and correct raw data.Gauged raw data is in the tight stage before re-constructing, and is called data for projection.Data for projection supplies to data storage cell 1028, and is stored in wherein.Re-construct unit 1024 and re-construct the tomographic image data according to the data for projection that remains in the data storage cell 1028.Read into from data storage cell 1028 be used for the data for projection that re-constructs unit 1024 that faultage image re-constructs the address by central control unit 1021 management.Carrying out faultage image when re-constructing, central control unit 1021 can switch pattern, and the pattern of the data that obtained by two systems of a kind of use of the data that the pattern of the data that a kind of use obtains by the first data snooping system 1011, a kind of use obtain by the second data snooping system 1012 arbitrarily according to pre-defined rule.
Obtain with data, channel failure monitor unit 1026 monitors the appearance of channel failure according to raw data or data for projection.Channel failure monitor unit 1026 is the data on the adjacency channel of detector 1113 and 1123 relatively.If the difference of the data value between adjacency channel is greater than a predetermined threshold, then channel failure monitor unit 1026 is determined to have occurred on one of adjacency channel to lose efficacy.Determine easily on which adjacency channel, to lose efficacy and occur.This be because in the difference of the difference of the data value between the adjacency channel on faulty channel and right side and the data value between faulty channel and left side adjacency channel all greater than threshold value.
When the number of channels of a plurality of passages of the detector 1113 that inefficacy has occurred on constituting it surpassed a predetermined quantity, channel failure monitor unit 1026 definite detectors 1113 had fault and can not use.Similarly, when the number of channels of a plurality of passages of the detector 1123 that inefficacy has occurred on constituting it surpassed a predetermined quantity, channel failure monitor unit 1026 definite detectors 1123 had fault and can not use.When definite detector 1113 or 1123 can not use, channel failure monitor unit 1026 supplied to central control unit 1021 to one with definite corresponding signal.
Receiving indication from channel failure monitor unit 1026 can not use the signal of detector 1113 or 1123 time, central control unit 1021 one with can not use detector 1113 or 1123 corresponding signals to supply to scan control unit 1014.When receiving and can not use detector 1113 or 1123 corresponding signals, scan control unit 1014 is carried out and the identical control operations that will carry out when electric arc occurs.Scan control unit 1014 stops tube voltage being applied to and determining on out of use detector 1113 or 1123 corresponding X-ray tubes 1111 or 1121 and stop to supply with the needed processing of filament heating current to it with respect to high-voltage generating unit 1013.If x-ray tube component 1110 and 1120 is equipped with the X ray shutter, then when voltage applies or with its closed independently shutter.
Fig. 3 is illustrated in the track of first and second X-ray tubes 1111 in the helical scanning and 1121, and vertical coordinate and abscissa are represented rotational angle and Z position respectively.When the indication helical scan mode, moving cell 1016 is arranged on the Z position of the second data snooping system 1012 position of moving a preset distance Δ d from the Z position of the first data snooping system 1011 backward.In addition, the movement velocity of the rotational angle and the table top 1031 of rotational stand is set under the control of scan control unit 1014, thereby second X-ray tube 1121 is followed helical orbit identical with first X-ray tube 1111 or much at one according to displacement Δ d.More particularly, above value is set, thereby the screw pitch of move distance that is defined as the table top revolution is consistent with four times displacement Δ d (360 °/move angle (being 90 ° in this case)).
In this helical scanning operation, are normal whiles at first X-ray tube 1111, obtain data for projection by the first data snooping system 1011, and the second data snooping system 1012 rotates under so-called idle condition and does not obtain any data for projection.In other words, first X-ray tube 1111 is in the normal period during it, and the X ray actual transmission is to object, and the X ray of transmission is surveyed by first X-ray tube 1113.In this period, object need not be from the x-ray bombardment of second X-ray tube 1121.By stopping tube voltage to the applying of second X-ray tube 1121, stop up X ray or another kind of device can be forbidden second X-ray tube, 1121 emission X ray with shutter.First X-ray tube 1111 is in the normal period during it, stops tube voltage to the applying of second X-ray tube 1121, but the effective supply of filament heating current to second X-ray tube 1121.This be a kind of shortening tube voltage begin to be applied on second X-ray tube 1121 instantaneous and actual transmission X ray and with the technology of the time lag between x-ray bombardment object instantaneous.
Figure 4 and 5 are curve charts, are used for explaining when the inefficacy such as paradoxical discharge having appeared in first X-ray tube 1111 or because the operation that the generation of channel failure will be carried out can not use first X-ray detector 1113 time.Should consider following some with reference to Figure 4 and 5.With reference to Fig. 4, vertical coordinate is represented rotational angle; And abscissa is represented the Z position.Different therewith, with reference to Fig. 5, the vertical coordinate express time; And abscissa is represented rotational angle.
To describe a kind of wherein inefficacy such as paradoxical discharge below and occur in situation in first X-ray tube 1111.Handle a kind of to have occurred in the identical mode of situation in first X-ray tube 1111 wherein because the generation of channel failure can not be used the situation of first X-ray detector 1113 with the inefficacy such as paradoxical discharge wherein.
With reference to Figure 4 and 5, the inefficacy such as paradoxical discharge is constantly
tOccurred in first X-ray tube 1111.Constantly
t, first X-ray tube 1111 is positioned at rotational angle θ 1 place, and second X-ray tube 1121 is positioned at rotational angle θ 2 places, and rotational angle θ 2 lags behind 90 ° than rotational angle θ 1.Constantly
t, scan control unit 1014 stops tube voltage being applied on first X-ray tube 1111, and stops to supply with a filament heating current to it.Constantly
t, scan control unit 1014 beginning is applied to a tube voltage on second X-ray tube 1121, and also begins detection by X-ray detector 1123 and the data by data acquistion system 1124 obtain.
Because data obtain to switch to the second data snooping system 1012 from the first data snooping system 1011 by this way when losing efficacy generation, even so stop the data acquisition in the first data snooping system 1011 because inefficacy occurs in, the second data snooping system 1012 also takes over operation.This makes might continue helical scanning.
Re-construct about tomographic image, by the moment when having taken place when losing efficacy
tThe data that obtained by the first data snooping system 1011 in the single pass circulation re-construct tomographic image before.The single pass circular definition (is generally 0 ° of position for X-ray tube 1111 wherein from a reference position; (180 °+fan angle alpha) take place a moment and rotated and re-construct (the circulation of 360 ° or 180 °+α) of a needed angular range of tomographic image in displacement periodically.
Tomographic image is handled and can be carried out simultaneously to realize so-called CT fluoroscopy with helical scanning, perhaps can be that the non real-time that begins after helical scanning is handled.
Comprising the generation moment of losing efficacy
tScan cycle in, by preparation and from re-constructing a corresponding data for projection of angle (360 ° or 180 °+α (segment angle)) that tomographic image is essential in the data of acquisition before the generation of losing efficacy and the data that after the inefficacy generation, obtain by the second data snooping system 1012, re-construct tomographic image by the first data snooping system 1011.Note and since the second data snooping system 1012 with respect to the first data snooping system 1011 with scheduled time lost motion, so with tightly constantly
t90 ° of corresponding data are before obtained by the first data snooping system 1011 and the second data snooping system 1012 redundantly.Re-construct unit 1024 and have a kind of on average function of such redundant data.This makes the picture quality might suppress owing to the change of sensitivity of the first data snooping system 1011 and the second data snooping system 1012 change suddenly.
Comprising that this inefficacy takes place constantly
tScan cycle after scan cycle in, the faultage image that equipment switches to the data that use obtains by the second data snooping system 1012 fully re-constructs processing.
As mentioned above, even the inefficacy such as paradoxical discharge occurs in the scanning process, perhaps,, data also can continue helical scanning by being obtained to switch to the second data snooping system 1012 from the first data snooping system 1011 because channel failure can not use detector.Obviously, in this case, a kind of situation that wherein can not carry out the data acquisition of the indication of losing efficacy.On this meaning, the inefficacy factor is not limited to the paradoxical discharge in X-ray tube, and may comprise owing to the emission of the other factors losing efficacy in cooling system and lost efficacy and obtain inefficacy in the unit in X-ray detector or data.Obviously, the present invention can be applicable to such inefficacy factor.
Secondly the situation of single section scanning will be described.In this case, half scanning will be described.Note also will describing the wherein inefficacy such as paradoxical discharge and occurred in situation in first X-ray tube 1111.To have occurred in the identical mode of situation in first X-ray tube 1111, handle a kind of wherein because the situation of first X-ray detector 1113 takes place to use channel failure with the inefficacy such as paradoxical discharge wherein.
Single section scanning is by rotate the operation of the single section of X-ray tube multiple scanning continuously in fixed mesa.Fig. 6 is illustrated in the track of first and second X-ray tubes 1111 in single section scanning and 1121, and vertical coordinate and abscissa be express time and rotational angle respectively.When specifying list section scan pattern, moving cell 1016 is arranged on identical position, Z position with the first data snooping system 1011 to the Z position of the second data snooping system 1012, and promptly the second data snooping system 1012 obtains and continuously by the position of the data for projection of the identical section of the first data snooping system, 1011 scannings therein.
In this single section scan operation, during first and second X-ray tubes 1111 and 1121 are the normal period during it, data for projection is obtained by the first and second data snooping systems 1011 and 1012, and mix the data that obtain by two data detection systems and re-construct the corresponding data of 180 °+α that need, re-construct faultage image data according to blended data thus with a preparation and a faultage image.As a result of, as shown in Figure 6, scan cycle can shorten to for 90 ° and rotate the time Δ t that needs.In other words, with the situation of wherein using a data detection system mutually specific energy double the temporal resolution of tomographic image.
Fig. 7 is a curve chart, is used for explaining the operation of carrying out when the inefficacy such as paradoxical discharge occurs in first X-ray tube 1111.With reference to Fig. 7, at moment t1, the inefficacy such as paradoxical discharge has occurred in first X-ray tube 1111.At moment t1, first X-ray tube 1111 is positioned at rotational angle θ 1 place, and second X-ray tube 1121 is positioned at rotational angle θ 2 places, and rotational angle θ 2 lags behind 90 ° than rotational angle θ 1.At moment t1, scan control unit 1014 stops tube voltage being applied on first X-ray tube 1111, and stops to supply with a filament heating current to it.In the identical moment, the data that scan control unit 1014 stops to be undertaken by the first data snooping system 1011 obtain.Simultaneously, scan control unit 1014 continues tube voltage is applied on second X-ray tube 1121, and supplies with a filament heating current to it.In addition, 1014 continuation of scan control unit are obtained by the data that the second data snooping system 1012 carries out.
In addition, according to auto restore facility, scan control unit 1014 restarts tube voltage to be applied on first X-ray tube 1111 and to supply with a filament heating current to it.When the inefficacy factor was paradoxical discharge, it was higher to recover possibility of success automatically.
Tomographic image re-constructs processing can carry out to realize so-called CT fluoroscopy simultaneously with single section scanning, perhaps can be that the non real-time that begins after single section scanning is handled.
As mentioned above, re-construct about faultage image, in the scan cycle before inefficacy time of origin t1, mixing re-constructs the corresponding data of 180 °+α that need by the first and second data snooping systems 1011 and 1012 data that obtain with a preparation and a faultage image, and re-constructs faultage image data according to blended data.
From t1 constantly lost efficacy taking place to the period of recovering t2 constantly, only according to repeating to re-construct faultage image data by the data for projection that obtains with the corresponding second data snooping system 1012 of the angle that re-constructs needs (360 ° or 180 °+α (fan-shaped angle)) of a faultage image.In this time period,, the scan cycle in the second data snooping system 1012 is extended to the time Δ t that rotation needs for 180 °+α, and the temporal resolution of tomographic image is reduced to 1/2 in this period as in the single-main distribution.Yet, can not continue scanning with stopping.
After recovering moment t2, restart the high time resolution operation, wherein mix the data that obtain by the first and second data snooping systems 1011 and 1012 preparing and the corresponding data of 180 °+α that re-construct faultage image needs, and re-construct faultage image data according to blended data.
As mentioned above, even the inefficacy such as paradoxical discharge takes place, scanning itself also can continue, although temporal resolution reduces.Obviously, in this case, a kind of situation that wherein can not carry out the data acquisition of the indication of losing efficacy.On this meaning, the inefficacy factor is not limited to the paradoxical discharge in X-ray tube, and can comprise the emission inefficacy owing to the other factors such as inefficacy in cooling system and the inefficacy in X-ray detector or data acquisition unit.Obviously, the present invention can be applicable to such inefficacy factor.
(second embodiment)
Fig. 8 represents the layout according to the major part of the X ray computed tomographic equipment of second embodiment.X ray computed tomographic equipment according to this embodiment comprises a scanning stand 2001 and computer installation 2002 (not shown)s.In computer installation 2002, preprocessor 2023, one re-construct unit 2024, image-display units 2025, and a bench board 2026 be connected on the central control unit 2021 through data/control bus 2022.
First x-ray tube component 2110 comprises one first X-ray tube 2111 and diaphragm apparatus 2112.Second x-ray tube component 2120 comprises one second X-ray tube 2121 and diaphragm apparatus 2122.In this case, a line that connects the center of the x-ray focus of first X-ray tube 2111 and first X-ray detector 2113 is called first centrage.Similarly, a line that connects the center of the x-ray focus of second X-ray tube 2121 and second X-ray detector 2123 is called second centrage.The first and second data snooping systems 2011 and 2012 position are designed like this, thereby first and second centrages intersect center of rotation axis RA, and second centrage leaves predetermined angular of first centrage of the disorder of internal organs axle line RA that rotates, for example 90 °.
A high-voltage generating unit 2013 is designed to, and tube voltage is applied on first and second X-ray tubes 2111 and 2121 and to it supplies with the filament heating current respectively.
Fig. 9 represents that an example of the layout of part takes place the tube voltage of high-voltage generating unit 2013.High-voltage generating unit 2013 is shared by first X-ray tube 2111 and second X-ray tube 2121.Yet, can provide high-voltage generator respectively for first X-ray tube 2111 and second X-ray tube 2121.High-voltage generating unit 2013 produces the tube voltage that will be applied between anode and the negative electrode.In addition, high-voltage generating unit 2013 produces and is used for the filament heating current of heat filament.High-voltage generating unit 2013 have a plurality of power supply 2131-1,2131-2 ..., 2131-n.A plurality of power supply 2131-1,2131-2 ..., 2131-n has identical fixedly output capacity, for example 40kV.Yet a plurality of power supplys needn't have identical output performance.For example, its positive terminal is connected to the anode 2231-1 of first and second X-ray tubes 2111 and 2121 and the capacity that the first power supply 2131-1 on the 2231-2 can have 60kV, and remaining power supply 2131-2 ..., 2131-n can have the capacity of 20kV.
Power supply 2131-1 ..., the negative terminal of 2131-n optionally is connected on the negative electrode 2232-1 of first X-ray tube 2111 through a selector 2133.Being applied to the anode of first X-ray tube 2111 and the voltage between the negative electrode can change in the scope from 60kV to (60+20 * (n-1)) kV with the step-length of 20kV by the selection undertaken by selector 2133.
Similarly, power supply 2131-1 ..., the negative terminal of 2131-n optionally is connected on the negative electrode 2232-2 of second X-ray tube 2121 through a selector 2132.Being applied to the anode of second X-ray tube 2121 and the voltage between the negative electrode can change in the scope from 60kV to (60+20 * (n-1)) kV with the step-length of 20kV by the selection undertaken by selector 2132.
The selection of being undertaken by selector 2133 is independent of the selection of being undertaken by selector 2132.Therefore high-voltage generating unit 2013 can be applied to different tube voltages on first and second X-ray tubes 2111 and 2121.Obviously, high-voltage generating unit 2013 can be applied to identical tube voltage on first and second X-ray tubes 2111 and 2121.
Supply to the preprocessor 2023 of computer installation 2002 respectively through the slip ring (not shown) of data acquisition unit 2114 and 2124 and continuous rotations of permission from the output of first and second X-ray detectors 2113 and 2123.Preprocessor 2023 is responsible for the data (data in this stage generally are called raw data) that obtain unit 2114 and 2124 transmissions from data are processed into the data (data in this stage generally are called data for projection) that are used to re-construct processing.This processing typically comprises: so-called N Reference Alignment is handled, wherein survey by reference detector owing to the variation of the x-ray irradiation dose that changes to the tube voltage of X-ray tube 2111 and 2121 and tube current, and according to probe value standardization raw data, the variation of corrected X radiation exposure dose thus; Proofread and correct to handle with water, wherein deduct the raw data of the water mirage that has obtained in advance by the raw data from the object P that will check, the X ray of offsetting by wedge shape wave filter etc. absorbs and the poor sensitivity between probe access.This processing also can comprise the processing of bundle hardening correcting, the processing of body motion correction etc.
Figure 10 A is the side view of first X-ray detector 2113.Figure 11 A is the vertical view of first X-ray detector 2113.First X-ray detector 2113 has a plurality of (being four in this case) the first detecting element line 2116.Four first detecting element lines 2116 are arranged side by side, thereby it vertically becomes and is parallel to slice direction (center of rotation axis RA).Each first detecting element line 2116 is by arranging that on slice direction in-line a plurality of first detecting elements 2115 constitute.Each first detecting element 2115 has a sensitizing range that first width is arranged at slice direction.First width is arranged to and slice thickness s1, and for example 8mm is corresponding.Therefore, the first data snooping system 2011 can obtain four thick slice of datas of continuous 8-mm simultaneously.Notice that the product of slice thickness s1 and element line quantity will be called total slice thickness S1 of the first data snooping system 2011.
Figure 10 B is the side view of second X-ray detector 2123.Figure 11 B is the vertical view of second X-ray detector 2123.Second X-ray detector 2123 has a plurality of (being four in this case) the second detecting element line 2126.Four second detecting element lines 2126 are arranged side by side, thereby it vertically becomes and is parallel to slice direction (center of rotation axis RA).Each second detecting element line 2126 is made of in-line a plurality of second detecting element 2125 of arranging on slice direction.Each second detecting element 2125 has a sensitizing range, the sensitizing range have with first detecting element 2115 at the identical width of the width on the channel direction and one second width on slice direction less than first width.Second width is designed to be for example slice thickness s2 of 0.5mm.Therefore, the second data snooping system 2012 can obtain four thick slice of datas of continuous 0.5-mm simultaneously.Notice that the product of slice thickness s2 and element line quantity will be called total slice thickness S2 of the second data snooping system 2012.
About the first and second data snooping systems 2011 and 2012, central control unit 2021 has three types the control model that is used for Z travel mechanism 2015.This control model of three types is selected by bench board 2026 by the operator.As shown in Figure 12, in first pattern, control to keep or to restart the centrage of the second data snooping system 2012 wherein the intersecting original state of centrage of the first data snooping system 2011.Therefore in first pattern, can obtain to have the slice of data of different slice thicknesses simultaneously by the first and second data snooping systems 2011 and 2012 in same position.
From diagnostic stand point, single pass allows the operator to obtain whole interior information roughly and pass through to obtain the detailed internal information of data acquisition near the part of regional center with little slice thickness by obtain data with large slice thickness in wide zone.
In second pattern, as shown in Figure 13, control so that the centrage of the second data snooping system 2012 is moved a preset distance Ad from the centrage of the first data snooping system 2011.Distance between the centrage of the centrage of the first data snooping system 2011 and the second data snooping system 2012 is by determining apart from sum with 1/2 total slice thickness S2 of the second data snooping system 2012 is corresponding with the corresponding distance of 1/2 total slice thickness S1 of the first data snooping system 2011.As mentioned above, in second pattern, a plurality of (being eight in this case) serial section data that slice thickness changes on the way can obtain simultaneously by the first and second data snooping systems 2011 and 2012 are set with preset distance (S1/2+S2/2).
From diagnostic stand point, single pass allows the operator to obtain whole interior information roughly and obtain detailed internal information by obtaining data with little slice thickness in the narrower zone adjacent with wide zone by obtain data with large slice thickness in wide zone.
In three-mode, according to controlling from the instruction of the second data snooping system 2012 with the distance between the centrage of the centrage that is arranged on the first data snooping system 2011 arbitrarily and the second data snooping system 2012.In three-mode, have the data of the section of different slice thicknesses by using the first and second data snooping systems 2011 and 2012 to obtain simultaneously in different any positions.From diagnostic stand point, single pass allows the operator to obtain whole interior information roughly and obtain data in the area-of-interest that part exists and obtain detailed internal information by influencing therein with little slice thickness by obtain data with large slice thickness in wide zone.
In a kind of scanning, the first and second data snooping systems 2011 and 2012 rotate with unequal angular velocity, and the sensitizing range of each detecting element 2125 of the second data snooping system 2012 is less than the sensitizing range of each detecting element 2115 of the first data snooping system 2011, and promptly the second data snooping system 2012 is lower than the first data snooping system 2011 aspect sensitivity.In order to proofread and correct this sensitivity difference, central control unit 2021 when carrying out scanning the dosage of being arranged to be higher than from the dosage of the X ray of second X-ray tube, 2121 emissions from the X ray of first X-ray tube, 2111 emissions.More particularly, be arranged to equal or be applied to no better than tube voltage on second X-ray tube 2121 being applied to tube voltage TV1 on first X-ray tube 2111, and the filament heating current (tube current: TC1) be arranged to less than the filament heating current (tube current: TC2) that supplies to second X-ray tube 2121 that supplies to first X-ray tube 2111.For example, the tube current that supplies to second X-ray tube 2121 is arranged to 250mA, and the tube current that supplies to first X-ray tube 2111 is arranged to 50mA.
The slice thickness of the second data snooping system 2012 is less, and the slice thickness of the first data snooping system 2011 is bigger.In the first data snooping system 2011, hard radiation is being effective aspect the observability of improving high contrast performance and tiny area.On the contrary, in the second data snooping system 2012, soft radiation is being effective aspect improvement low contrast performance and the increase density.For this purpose, lower tube voltage, for example a 80kV, be applied to from high-voltage generating unit 2013 on the X-ray tube 2111 of the first data snooping system 2011, and a upper pipe voltage, for example 140kV is applied on second X-ray tube 2121 from high-voltage generating unit 2013.
As mentioned above, according to this embodiment, can obtain simultaneously about having different slice thicknesses and the data that are positioned at the section at same position place by single pass, data can be obtained by single pass simultaneously as serial section, and data can be obtained simultaneously about a plurality of sections with different slice thicknesses by single pass about a plurality of sections with different slice thicknesses.
As Figure 14 A, 14B, 15A, and 15B as shown in, one first X-ray detector 2213 can be by constituting with the corresponding detecting element line 2213 of the slice thickness of for example 2mm, and one second X-ray detector 2223 can be by constituting with corresponding four the detecting element lines 2213 of the slice thickness of for example 0.5mm, thereby total slice thickness becomes and equals the slice thickness of detecting element line 2213.In this case, can obtain about the data of the thick section of about 2-mm simultaneously and be the data of four sections of 0.5mm * 4 about its total slice thickness.From diagnostic stand point, can observe data in same area roughly with a thick section, and can observe inside in detail with a plurality of slices.
As shown in Figure 16 A and 16B, one first X-ray detector 2313 can be by constituting with corresponding four the detecting element lines 2316 of the slice thickness of for example 2mm, and one second X-ray detector 2323 can be by constituting with corresponding four the detecting element lines 2326 of the slice thickness of for example 1mm, thereby total slice thickness becomes and equals total slice thickness of two detecting element lines 2316.In this case, as shown in Figure 17, carry out data with four slices and obtain in central region, and simultaneously, can obtain data with the thick section of slice thickness with 2mm, these thick sections are adjacent with the both sides of four sections that are arranged in central region.From diagnostic stand point, can observe central region in detail with four slices, and can observe the both sides of central region roughly with thick section.
(the 3rd embodiment)
Figure 18 represents the layout according to the major part of the X ray computed tomographic equipment of this embodiment.Comprise a scanning stand 3001, a computer installation 3002 and a bed (not shown) according to the X ray computed tomographic equipment of this embodiment.Scanning stand 3001 is constituent elements that are used for obtaining about the data for projection of the object that will check.This data for projection is loaded in the computer installation 3002, and is subjected to the processing such as image re-constructs.Object lie in the bed table top on the time, be inserted into scanning stand 3001 imaging region in.
First x-ray tube component 3110 comprises one first X-ray tube 3111 and is arranged in peripheral elements between first X-ray tube 3111 and the object, for example is installed in the first X ray collimator 3112 of a position of the tight front of X-radiation window of first X-ray tube 3111.3112 restrictions of the first X ray collimator are from the dispersion angle (segment angle or visual angle) of the X ray of first X-ray tube, 3111 emissions.The first X ray collimator 3112 has the driver element of polylith barricade shield plate and difference maneuvering board.The position of each piece by control polylith barricade shield plate is adjustment aperture width and aperture center position arbitrarily.
Second x-ray tube component 3120 also comprises one second X-ray tube 3121 and the peripheral elements such as the second X ray collimator 3122.The second X ray collimator 3122 also limits from the dispersion angle (segment angle) of the X ray of second X-ray tube, 3121 emissions.The second X ray collimator 3122 has the driver element of polylith barricade shield plate and difference maneuvering board.The position of each piece by control polylith barricade shield plate is adjustment aperture width and aperture center position arbitrarily.
High-voltage generating unit 3013 has the high tension generator with first and second X-ray tubes 3111 and 3121 corresponding two systems, so that apply and supply pipe voltage and filament heating current (tube current is by the control of filament heating current) to first and second X-ray tubes 3111 and 3121 respectively.Tube voltage and filament heating current these high tension generators from two systems under the control of scan control unit 3014 apply/supply to first and second X-ray tubes 3111 and 3121.Except that control for high-voltage generating unit 3013, the all operations control that scanning requires is responsible in scan control unit 3014, for example rotation of the setting of the first and second X ray collimators 3112 and 3122 aperture and aperture center position, rotational stand, and the motion of table top.
From the output of first and second X-ray detectors 3113 and 3123 as data for projection through data obtain slip ring (not shown) that unit 3114 and 3124, one allow to rotate continuously, and preprocessor supply with computer installation 3002.The data for projection that data supplementary units 3023 usefulness of computer installation 3002 are obtained by first X-ray detector 3113 replenishes the lost part of the data for projection that is obtained by second X-ray detector 3123.Image re-constructs unit 3024 and re-constructs the tomographic image data according to replenishing data for projection.This data are presented on the image-display units 3025 then.
Figure 19 represents by first and second X ray collimators 3112 of scan control unit 3014 adjustings and 3122 aperture.The aperture of the second X ray collimator 3122 is arranged to aperture greater than the first X ray collimator 3112.The aperture A1 of the first X ray collimator 3112 is provided with according to visual field FOV, to use the whole zone from the x-ray bombardment object section of first X-ray tube 3111.The aperture A2 of the second X ray collimator 3122 is arranged to less according to ROI, only be radiated at interesting areas ROI in the object section specially to use the X ray from second X-ray tube 3121, and do not shine the part except that area-of-interest.In practice, can each aperture be set to and the corresponding standard value of parameter such as the type of the physique of object and area-of-interest, perhaps can be arranged to for the unique value of object by the tomographic image that obtains by the prescan under low dosage.
As mentioned above, scan by means of different apertures.In single pass, the x-ray dose of launching from first X-ray tube 3111 is lower than from the x-ray dose of second X-ray tube, 3121 emissions.More particularly, the tube voltage TV1 that is applied to first X-ray tube 3111 is arranged to equal or is applied to no better than the tube voltage TV2 on second X-ray tube 3121, and the filament heating current (tube current: TC1) be arranged to less than the filament heating current (tube current: TC2) that supplies to second X-ray tube 3121 that supplies to first X-ray tube 3111.For example, the tube current that supplies to second X-ray tube 3121 is set to 250mA, and the tube current that supplies to first X-ray tube 3111 is set to 50mA.By identical tube voltage and different tube currents are set by this way, can be provided with soft specially or hard radiation, although different exposure doses is set.
Be arranged on the data supplementary units 3023 that supplies to computer installation 3002 in the single pass by first and second X-ray detectors 3113 and 3123 data for projection of surveying by means of these.In the second data snooping system 3012, X ray does not cover the whole zone of object section, and in fact the data for projection of therefore only being surveyed by second X-ray detector 3123 can not re-construct tomographic image.In other words, in some of the passage of second X-ray detector 3123 because smaller aperture due width omitted data.The data for projection that data supplementary units 3023 is used on the respective channel of first X-ray detector 3113 replenishes such omission channel data.
Figure 20 represents the track of first and second X-ray tubes 3111 and 3121.Second X-ray tube 3121 is positioned at respect to first X-ray tube 3111 and 90 ° of corresponding positions that lag behind, and the track that therefore draws and postpone 90 ° with the track that is drawn by first X-ray tube 3111.Consider rotational angle α °.Figure 21 represents to distribute when second X-ray tube 3121 is positioned at the rotational angle α ° of data for projection of being surveyed by second X-ray detector 3123 when locating.Obviously, the data on the corresponding passage of part of omission and x-ray bombardment of no use.When first X-ray tube 3111 is positioned at identical rotational angle α ° when locating, finish the data for projection that has taken place therein on the data elliptical passage by means of the data for projection on the same channels of surveying by first X-ray detector 3113.
In practice because different x-ray irradiation doses is set, and thereby different reference levels is set, so the weighting/data that add drop shadow are so that reference level is even.Allow the θ be rotational angle, ch is a passage, and PD1 is the data for projection of being surveyed by first X-ray detector 3113, and PD2 is the data for projection of being surveyed by second X-ray detector 3123, is provided by following formula from the data for projection PD of data supplementary units 3023 outputs
PD(θ，ch)＝a·PD1(θ，ch)+b·PD2(β，ch)
Wherein
aWith
bBe weighting factor, its relation table is shown a＞b, and these values are set to satisfy a=c ● b, wherein
cIt is the exposure dose ratio of first X-ray tube 3111 and second X-ray tube 3121.Suppose exposure dose
cBe (50mA/250mA)=1/5, a=5 and b=1 are set.
In practice, following processing is typical.Taken place thereon on the passage in the data elliptical second data snooping system 3012 weighting factor to be changed to a=5 and b=0, and do not take place thereon on the passage in the data elliptical second data snooping system 3012 weighting factor to be changed to a=0 and b=1, use the data for projection that obtains by the first data snooping system 3011 only to replenish the data that data elliptical passage has taken place on it thus.
Have the X ray of narrow segment angle and high exposure dose and X ray by use with wide segment angle and low exposure dose, part with respect to necessity, it is area-of-interest, can realize high-resolution and high image quality, simultaneously with wherein compare with the situation of x-ray bombardment area-of-interest and whole remaining area with high exposure dose, can suppress exposure dose lowlyer.
In the actual imaging process, need following process.Under with the situation of low exposure dose, carry out prescan by using one of data snooping system 3011 and 3012 with the whole zone of x-ray bombardment object section.Distinguish interesting areas by generating tomographic image with low resolution then.The aperture of the second X ray collimator 3122 is set according to the size of area-of-interest.In addition, as shown in Figure 22, by regulating the state that table top guarantees wherein to be positioned at the area-of-interest on the pivot center RA in the horizontal and vertical directions.In this state, during turning can fix the aperture location of the second X ray collimator 3122.
As shown in Figure 23, guarantee that the state that area-of-interest wherein is positioned on the pivot center RA may be impossible or difficult.In this case, must be arranged to always to be captured in area-of-interest in the visual field of X ray to wide aperture and irrelevant with the rotational angle of second X-ray tube 3121 in changes.Yet,, can not make the exposure dose minimum by means of this set.Reason for this reason, following operation is effective.Reduce the aperture of the second X ray collimator 3122 according to the size of region of interest ROI.Thereafter, the rotational angle of second X-ray tube 3121 is irrelevant in changeing with one for the area-of-interest in the narrow visual field that always is captured in X ray, by means of synchronously the move aperture location of the second X ray collimator 3122 of rotational angle.
By the position of the position of the area-of-interest on the tomographic image that in prescan, obtains, pivot center RA, and the focal position of second X-ray tube 3121 between the position relation, can obtain in the aperture location of the second X ray collimator 3122 and the relation between the rotational angle with method of geometry.According in the aperture location of the second X ray collimator 3122 and the relation between the rotational angle, the second X ray collimator 3122 can be controlled in scan control unit 3014, with synchronously the move aperture location of the second X ray collimator 3122 of rotational angle.
(the 4th embodiment)
Figure 24 represents the layout according to the major part of the X ray computed tomographic equipment of the 4th embodiment.X ray computed tomographic equipment according to this embodiment comprises a scanning stand 4001 and computer installation 4002.Scanning stand 4001 is constituent elements that are used for obtaining about the data for projection of the object that will check.This data for projection is loaded in the computer installation 4002, and is subjected to the processing such as image re-constructs.Computer installation 4002 comprise a true preparation control unit 4021 and through one single data/control bus 4028 be connected thereto as lower unit: preprocessor 4023, an image re-construct unit 4024, image-display units 4025, bench board 4026, and memorizer 4027.
Object on the table top 4020 that lies in a bed 4010 in, be inserted into scanning stand 4001 in.The table top 4020 of bed 4010 is driven with motion longitudinally by a bed driver element 4017.Usually, bed 4010 is installed like this, thereby this vertically becomes and is parallel to pivot center RA (identical with body axis and z axis).A table position pick off 4018 is provided as the position of surveying table top 4020, and is formed by for example rotary encoder.
For scanning stand 4001 provides an annular rotational stand (not shown), so that drive with the rotation axis RA rotation that rotates by a stand driver element 4016.Each is installed on this rotational stand by a plurality of data snooping system that x-ray tube component constitutes.In this case, two data detection systems will be described.At one is that one first X-ray detector 4113 of the multi-channel type of one first x-ray tube component 4110 and relative first x-ray tube component 4110 is installed on the rotational stand in the first data snooping system 4011 of one of two systems.In one second data snooping system 4012, one second X-ray detector 4123 of the multi-channel type of one second x-ray tube component 4120 and the relative second data snooping system 4012 is installed on the rotational stand, intersects at the central axis of the first data snooping system 4011 at pivot center RA place thereby the central axis of the second data snooping system 4012 (is assumed to 90 ° here) at a predetermined angle.
First x-ray tube component 4110 comprises that one first X-ray tube 4111 and one are used for removing the mental retardation component to reduce the first X ray wave filter 4112 of exposure dose.Similarly, second x-ray tube component 4120 comprises one second X-ray tube 4121 and one second X ray wave filter 4122.A Z travel mechanism 4013 is placed on first x-ray tube component 4110 and first X-ray detector 4113, reaches between the rotational stand.Z travel mechanism 4013 has and need to support first x-ray tube component 4110 and first X-ray detector 4113 so that allow a kind of structure and the power supply that they move on the direction that is parallel to or almost is parallel to pivot center RA.Z travel mechanism 4013 receives the power of supplying with from Z travel mechanism driver element 4019, and electric motion first x-ray tube component 4110 and first X-ray detector 4113.
The converter type high-voltage generating unit 4014 of two systems and 4015 provides so that power respectively to it for first and second X-ray tubes 4111 and 4121.High- voltage generating unit 4014 and 4015 each comprise a tube voltage switch and heater current switch so that arbitrarily or stepping ground adjustable pipe voltage and heater current.
From the output of first and second X-ray detectors 4113 and 4123 as data for projection through data obtain slip ring (not shown) that unit 4114 and 4124, one allow to rotate continuously, and a preprocessor 4023 supply to an image and re-construct unit 4024, and stand the processing that re-constructs of tomographic image data.This tomographic image data show on an image-display units 4025, and also supply to one for example to be used for determining after with the true preparation control unit 4021 of the processing of the starting point of the main scanning operation described.
The various information (will afterwards describe) of a bench board 4026 with permission operator input such as the condition of scanning (will describe afterwards), main scanning triggering, pre-triggering etc. are provided.Provide a memorizer 4027, with the data of storage input scan condition with along with the carrying out of image forming program supplies to true preparation control unit 4021 to data in suitable timing.
The control operation that relates to the contrast media imaging by true preparation control unit 4021 will be described below.About this control operation, truly prepare control unit 4,021 four types operator scheme can using according to operator's Instruction Selection is housed.Following order is described this operator scheme of four types.
(first control operation)
Figure 25 represents to be used for the process of the first operation control.At first, the operator is provided with the condition of scanning (S1) by bench board 4026.Then the condition of scanning is stored in the memorizer 4027.As shown in Figure 26, the condition of scanning comprise position P1 by the monitor scans of the first data snooping system 4011, at the starting position P3 of the imaging region that is used for the main scanning (helical scanning) by the second data snooping system 4012, and end position P4.The condition of scanning also comprises X ray condition (monitor scans tube voltage and monitor scans tube current) that is used for monitor scans and the X ray condition (main scanning tube voltage and main scanning tube current) that is used for main scanning.Typically, the monitor scans tube voltage is arranged to equal the main scanning tube voltage so that soft/hard radiation is set specially.The monitor scans tube current is arranged to less than the main scanning tube current so that suppress exposure dose.In addition, the condition of scanning comprises table top speed and sweep time (one changes the time of needs), as the parameter that is used for determining screw pitch (move distance of revolution table top).
When the description condition is set, true preparation control unit 4021 is by adding distance between the starting position P3 at the position of monitor scans P1 and the imaging region that is being used for main scanning, the distance A D (S2) of calculating between the plane of scanning motion of first and second data snooping system 4011 and 4012 to one through it at table top reaches the table top speed the helical scanning from the halted state of table top the distance D A that needs near run duration.When table top in the opposite direction moves, by from the position of monitor scans P1 and be used for distance between the starting position P3 of imaging region of main scanning and deduct one and reach the distance D A near the run duration needs of the table top speed the helical scanning at table top from the halted state of table top through it, the distance, delta D of calculating between the plane of scanning motion of the first and second data snooping systems 4011 and 4012, as shown in Figure 27.
True preparation control unit 4021 control Z travel mechanism driver elements 4019 are to separate a computed range AD (S3) to the plane of scanning motion of the first data snooping system 4011 with the plane of scanning motion of the second data snooping system 4012.Operator's manual operation table top 4020 then navigates to monitor scans position P1 with a specific region of the object that will check.At this moment, the second data snooping system 4012 is in before the starting position P3 that is located at the imaging region that is used for main scanning near the spare space P2 of range ability DA.
When finishing above position when being provided with, truly prepare control unit 4021 control stand driver elements 4016 with beginning rotational stand (S4), and set up first high-voltage generating unit 4014 according to the X ray condition that is used for monitor scans.Simultaneously, truly prepare control unit 4021 according to the foundation that is used for finishing second high-voltage generating unit 4015 in the X ray condition of the main scanning in this stage.More particularly, true preparation control unit 4021 is provided with the tube voltage switch of high- voltage generating unit 4014 and 4015 according to monitor scans tube voltage and main scanning tube voltage, and the heater current switch of high- voltage generating unit 4014 and 4015 is set according to monitor scans tube current and main scanning tube current.True preparation control unit 4021 begins the filament heating current is supplied to first and second X-ray tubes 4111 and 4121 to preheat filament (S5) then.
When finishing above preparatory function and stand velocity of rotation and reach constant speed, truly prepare control unit 4021 beginning monitor scans (S6).In other words, true preparation control unit 4021 supplies to first high-voltage generating unit 4014 and begins to launch X ray by emission is triggered, and also begin in first X-ray detector 4113 the signal amplification that charge storage/read circulates, data obtain unit 4114, analog/digital conversion, and data read circulation.True preparation control unit 4021 further control figures look like to re-construct unit 4024, distribute as the tomographic image data so that re-construct attenuation quotient by the data for projection that obtains by the monitor scans in real time, and make image-display units 4025 show it (S7).Repeat this monitor scans, image continuously and re-construct, and show, up in step S12, stopping to handle (will describe afterwards).
The operator observes this tomographic image, the dye levels of area-of-interest (target blood) in section particularly, and when dye levels increases to a certain degree, be used for the pre-triggering (S8) of main scanning by bench board 4026 inputs.
Respond this pre-triggering, true preparation control unit 4021 control bed driver elements 4017 are with setting in motion table top 4020, and also control Z travel mechanism driver element 4019 with in the same direction with the identical speed setting in motion first data snooping system 4011 (S9) of table top motion.Along with this motion, the starting position P3 in the main scanning zone moves closer to spare space (main scanning position) P2 of the second data snooping system 4012.Also during this period, continue monitor scans, image re-constructs and show, and the operator observes tomographic image, the dye levels of area-of-interest (target blood) in section particularly, thereby be used for the triggering (S10) of main scanning in due course by bench board 4026 inputs.
Response is used for this triggering of main scanning, truly prepares control unit 4021 and starts main scanning (helical scanning) (S11).In other words, true preparation control unit 4021 supplies to second high-voltage generating unit 4015 and begins to launch X ray by emission is triggered, and also begin in second X-ray detector 4123 the signal amplification that charge storage/read circulates, data obtain unit 4124, analog/digital conversion, and data read circulation.Note,, then truly prepare control unit 4021 and begin main scanning automatically if when the starting position P3 in the main scanning zone reaches the spare space P2 of the second data snooping system 4012, do not import the triggering that is used for main scanning.
This main scanning continues, and reaches the spare space P2 (S12) of the second data snooping system 4012 up to the end position P4 in the main scanning zone.When the end position P4 in the main scanning zone reaches the spare space P2 of the second data snooping system 4012, truly prepare control unit 4021 and stop monitor scans (S13) with main scanning.
As mentioned above, according to this control procedure, because the plane of scanning motion of the first data snooping system 4011 and the plane of scanning motion of the second data snooping system 4012 separate a distance, delta D in advance, so can shorten to the waiting time that is used for the table top motion near the needed time of operation.In addition, owing to monitor scans is undertaken by the first data snooping system 4011, and main scanning is undertaken by the second data snooping system 4012, so tightly can monitor dye levels before main scanning.In addition, because monitor scans and main scanning undertaken by the first and second data snooping systems 4011 and 4012 respectively, so can finish the foundation that is used for the X ray emission in advance according to main-scan condition.This makes and might begin main scanning rapidly when receiving triggering.
(second control operation)
Manually the input main scanning triggers in first control operation.Yet in second control operation, the operation after the pre-input that triggers is automatic.Figure 28 represents to be used for the process of second control operation.Indicate identical step among Figure 28 with label identical in Figure 25, and the descriptions thereof are omitted.Figure 29 represents to be applied to tube voltage on first and second X-ray tubes 4111 and 4121 for the variation for the time of the variation of time and table top speed, so that provide the other explanation for the description of second control operation.
In this second control operation, as the condition of scanning, be provided with as follows: except that the position P1 of the monitor scans by the first data snooping system 4011, stop in monitor scans (pre-trigger input) DLT1 time delay between beginning to main scanning, starting position P3, the end position P4 of the imaging region that is used for the main scanning by the second data snooping system 4012, be used for monitor scans the X ray condition, be used for the X ray condition of main scanning and be used for determining the table top speed and the sweep time (S1 ') of screw pitch.Consider that contrast medium and blood flow flow to the time that main scanning starting position P3 (consistent with the scanning position P3 of the second data snooping system 4012 at moment T3) needs from the position P1 of the monitor scans by the first data snooping system 4011, this time delay of DLT1 is set.By setting in advance this time delay of DLT1, when the dye levels of tomographic image reaches when being used for optimum degree that main scanning begins, the operator can import pre-a triggering.In other words, consider that contrast medium and blood flow flow to the time that the starting position P3 the imaging region needs from monitor scans position P1, needn't deliberately postpone to import the timing of pre-triggering.
Because in the pre-operation that triggers after importing is automatic, stop monitor scans (S21) so truly prepare control unit 4021 control first X-ray detectors 4113 and first data acquisition unit 4114 in response to the pre-triggering input among the step S8, thereby prevent for radiating unnecessary exposure.
True preparation control unit 4021 is only being pass by then by the time T 2 after deducting a time D LT2 who obtains near running time T a from the preset delay time from pre-triggering T1 input time, setting in motion table top 4020 (S22).Time T 3 when having finished near operation when table top 4020, the starting position P3 in the main scanning zone reaches the spare space P2 (S23) of the second data snooping system 4012.At this moment, beginning main scanning (S24).Because monitor scans stops, so when the end position P4 in the main scanning zone reaches the position P2 of the second data snooping system 4012 (S12), truly prepare control unit 4021 and stop main scanning (S13 ').
As mentioned above, according to second control operation, except that the effect that obtains by first control operation,, can eliminate difference and each difference that main scanning picks up counting by in the pre-automatic operation that triggers after importing.This makes might stably carry out main scanning.
(the 3rd control operation)
In first control operation, manually input is pre-triggers and the main scanning triggering.In second control operation, manually input is pre-triggers.Yet in the 3rd control operation, triggering input operation and main scanning triggering input operation in advance is fully automatically.Figure 30 represents to be used for the process of the 3rd operation control.Indicate identical step among Figure 30 with label identical in Figure 25 and 28, and the descriptions thereof are omitted.Figure 31 represent to be applied on first and second X-ray tubes 4111 and 4121 tube voltage for the variation of time, table top speed for the variation of time, and in the tomographic image that obtains by monitor scans the meansigma methods of the CT value of the pixel in the area-of-interest for the variation of time, so that provide other explanation for the description of the 3rd control operation.
In the 3rd control operation, as the condition of scanning, be provided with as follows: automatic area-of-interest and a threshold value of except that the position P1 of the monitor scans by the first data snooping system 4011, being used for triggering in advance input operation, starting position P3 at the imaging region that is used for the main scanning by the second data snooping system 4012, end position P4, the X ray condition that is used for monitor scans, the X ray condition that is used for main scanning, be used for determining the table top speed and the sweep time of screw pitch, and contrast medium and blood flow flow to the time that main scanning starting position P3 needs from the position P1 of the monitor scans by the first data snooping system 4011, promptly stops (pre-trigger input) and the main scanning DLT1 time delay (S1 ") between beginning in monitor scans.
The CT value of a plurality of pixels of true preparation control unit 4021 from the current area-of-interest of tomographic image data pick-up that among step S7, obtains, and the meansigma methods (S31) of calculating CT value.True preparation control unit 4021 is then the CT value of calculating (meansigma methods) compare with preset threshold value (S32).If the CT value is no more than threshold value, then truly prepare control unit 4021 and determine in the dye levels at monitored position P1 place too lowly, and with respect to the tomographic image data that obtain of order, repeat the extraction of CT value, mean value calculation, reach and the comparison of threshold value.
In the time T 1 when the CT value surpasses threshold value, truly prepare control unit 4021 and determine that the dye levels at monitored position P1 place is suitable, and stop monitor scans (S21).Such in step S22, from the time T 1 when the CT value has surpassed threshold value when by deduct the time T 2 of the time D LT2 that obtains near running time T A when over and done with from the preset delay time, truly prepare control unit 4021 setting in motion table tops 4020 (S33).Time T 3 when having reached the spare space P2 (S23) of the second data snooping system 4012 as the starting position P3 in the main scanning zone is truly prepared control unit 4021 beginning main scannings (S24).When the end position P4 in the main scanning zone reaches the position P2 of the second data snooping system 4012 (S12), truly prepare control unit 4021 and stop main scanning (S13 ').
As mentioned above, according to the 3rd control operation, except that the effect of first and second control operations, the operation that comprises pre-triggering input operation can be fully automatically.
(the 4th control operation)
In the second and the 3rd control operation, set in advance from monitor scans and stop to DLT1 time delay that main scanning begins.In the 4th control operation, this time delay, DLT1 was by calculating of being undertaken by true preparation control unit 4021.Figure 32 A and 32B represent to be used for the process of the 4th operation control.With identical step among label indicator diagram 32A identical in Figure 25,28 and 30 and the 32B, and the descriptions thereof are omitted.Figure 33 represents: in based on the area-of-interest in the tomographic image data of the data for projection that in monitor scans, obtains by the first data snooping system 4011 with respect to the time, the variation of the meansigma methods of pixel CT value; With in based on the area-of-interest in the tomographic image data of the data for projection that in monitor scans, obtains by the second data snooping system 4012 with respect to the time, the variation of the meansigma methods of pixel CT value is so that provide other explanation for the description of the 4th control operation.
In this 4th control operation, monitor scans is not only carried out by the first data snooping system 4011 but also by the second data snooping system 4012.Therefore, in step S5 ',, set up second high-voltage generating unit 4015 and first high-voltage generating unit 4014 according to the X ray condition that is used for monitor scans.
True preparation control unit 4021 is controlled first and second high- voltage generating units 4014 and 4015, first and second X-ray detectors 4113 and 4123, is reached first and second data acquisition unit 4114 and 4124, to begin monitor scans (S41) in two data detection systems 4011 and 4012.According to obtaining unit 4114 by the data for projection that monitor scans obtains, re-construct tomographic image data (the first tomographic image data) by data.With this operation,, re-construct tomographic image data (the second tomographic image data) (S42) according to obtaining unit 4124 by the data for projection that monitor scans obtains by data.
True preparation control unit 4021 presets the CT value of a plurality of pixels in the area-of-interest from the first tomographic image data pick-up that obtains among step S42, and calculates the meansigma methods (first meansigma methods) of CT value.With this operation, truly prepare the CT value of a plurality of pixels of control unit 4021 from the second tomographic image data pick-up area-of-interest that among step S42, obtains, and the meansigma methods (second meansigma methods) of calculating CT value (S41).True preparation control unit 4021 is then first meansigma methods of calculating compare with a preset threshold value CT2 (S44).
If first meansigma methods is no more than threshold value CT2, then truly preparing control unit 4021 determines in the dye levels at monitored position P1 place too low, and the tomographic image data with respect to order obtains repeat first and second mean value calculation and the comparison between first meansigma methods and threshold value.True preparation control unit 4021 is stored in each first and second meansigma methods constantly in the memorizer 4027 then.When first meansigma methods surpasses threshold value CT2, truly prepare control unit 4021 and stop monitor scans (S45) by the first and second data snooping systems 4011 and 4012.
True preparation control unit 4021 is then according to the change calculations time delay DLT1 (S46) of first and second meansigma methodss of storing with respect to the time.This time delay, DLT1 represented that contrast medium and blood flow flow to time of main scanning starting position P3 needs from the position P1 of the monitor scans by the first data snooping system 4011, had promptly reached the moment of particular value (threshold value CT2) and had reached time difference between moment of particular value in the dye levels at P3 place, main scanning starting position in the dye levels at monitored position P1 place.Owing to almost follow in the variation of the CT value at monitored position P1 place with respect to the variation of time with respect to the time in the CT value at the P2 place, spare space of the second data snooping system 4012, so specify in time T 12 when the CT value at monitored position P1 place has reached threshold value CT2 in the CT value at the P2 place, spare space of the second data snooping system 4012, and from the storage data pick-up when the time T 11 when the CT of monitored position P1 value is CT1.This makes might be estimated as the time width between T11 and T12 DLT1 time delay.
When over and done with by when computing relay time D LT1 deducts the time D LT2 that obtains near running time T A from the time T when first meansigma methods has surpassed threshold value CT2 12, truly prepare control unit 4021 setting in motion table tops 4020 (S47), and set up second high-voltage generating unit 4015 (S48) according to the X ray condition that is used for main scanning.
When the starting position P3 in the main scanning zone has reached the spare space P2 of the second data snooping system 4012 (S23), the 4012 beginning main scannings (S24) of the second data snooping system.When the end position P4 in the main scanning zone reaches the position P2 of the second data snooping system 4012 (S12), truly prepare control unit 4021 and stop main scanning (S13 ').
As mentioned above, according to the 4th control operation, except that the effect of first, second and the 3rd control operation, can eliminate setting and stop to the necessity of DLT1 main scanning begins time delay from monitor scans.
Expect additional advantage and modification easily for those skilled in the art.Therefore, the present invention its more broad aspect be not limited to detail and the representative embodiment representing and describe here.Thereby, can carry out various modifications, and not break away from spirit and scope by the general inventive concept of appended claims book and the definition of its equivalent.
Claims (14)
1. X ray computed tomographic equipment comprises:
One first detection system has first X-ray tube of the object that will check with x-ray bombardment with first exposure dose and first X-ray detector that detection sees through the X ray of object;
One second detection system has one to see through second X-ray detector of the X ray of object with second X-ray tube of x-ray bombardment object and detection than high second exposure dose of first exposure dose; And
A motion is configured on the body axis direction of object at least one of the motion first and second data snooping systems.
2. equipment according to claim 1, wherein first detection system is used for monitor scans so that monitor CT value or contrast Media density, and the second data snooping system is used for main scanning.
3. equipment according to claim 2 further comprises a control unit, is configured to controlled motion mechanism, so that the first data snooping system is arranged on the primary importance place and the second data snooping system is arranged on second position place.
4. equipment according to claim 2 comprises that further re-constructs a unit, is configured to re-construct first view data in real time according to the output from first detector of the first data snooping system.
5. equipment according to claim 4, wherein control unit is determined picking up counting of main scanning according to first view data.
6. equipment according to claim 5, wherein control unit stopped to use the x-ray bombardment object from first X-ray tube before main scanning.
7. equipment according to claim 5, wherein control unit began a filament heating current is supplied to second X-ray tube before main scanning.
8. equipment according to claim 5, wherein control unit is pixel value in area-of-interest in first view data or from a value and a threshold of its derivation, with picking up counting of definite main scanning.
9. equipment according to claim 8, wherein control unit is defined as picking up counting of main scanning at the time point when lighting an over and done with predetermined amount of time when pixel value in area-of-interest first view data or the time when the value of its derivation has reached threshold value.
10. equipment according to claim 3 is wherein the distance between the starting position of position that is arranged in monitor scans in the distance between first and second position and main scanning.
11. equipment according to claim 3 is wherein being defined as in the distance between first and second position by the distance between the starting position of the position of monitor scans and main scanning being added or deducts the distance that obtains near the needed distance of operation of the table top of placing object on it.
12. equipment according to claim 2, wherein control unit begins main scanning according to the instruction from operator's beginning main scanning.
13. equipment according to claim 2, wherein when the time point from from the over and done with predetermined amount of time of the instruction of operator's beginning main scanning the time, control unit begins main scanning.
14. equipment according to claim 2, wherein before monitor scans finished, control unit began the filament heating current is supplied to second X-ray tube.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
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| JP320925/2001 | 2001-10-18 | ||
| JP320929/2001 | 2001-10-18 | ||
| JP2001320925A JP3977623B2 (en) | 2001-10-18 | 2001-10-18 | X-ray computed tomography system |
| JP320928/2001 | 2001-10-18 | ||
| JP320926/2001 | 2001-10-18 |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN02147227.0A Division CN1281188C (en) | 2001-10-18 | 2002-10-18 | Computerised tomograph |
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| CN1736335A true CN1736335A (en) | 2006-02-22 |
| CN100443054C CN100443054C (en) | 2008-12-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005101037396A Expired - Fee Related CN100443054C (en) | 2001-10-18 | 2002-10-18 | X-ray computed tomographic equipment |
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| JP (1) | JP3977623B2 (en) |
| CN (1) | CN100443054C (en) |
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| CN107661112A (en) * | 2016-07-27 | 2018-02-06 | 上海联影医疗科技有限公司 | The scanning time computational methods of CT system and scanning prepare process display methods |
| CN106290283A (en) * | 2016-09-09 | 2017-01-04 | 华中科技大学 | A kind of method of quick obtaining biological tissue images data |
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| JP3977623B2 (en) | 2007-09-19 |
| JP2003116834A (en) | 2003-04-22 |
| CN100443054C (en) | 2008-12-17 |
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