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WO2009096361A1 - Appareil de tomodensitométrie - Google Patents

Appareil de tomodensitométrie Download PDF

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Publication number
WO2009096361A1
WO2009096361A1 PCT/JP2009/051199 JP2009051199W WO2009096361A1 WO 2009096361 A1 WO2009096361 A1 WO 2009096361A1 JP 2009051199 W JP2009051199 W JP 2009051199W WO 2009096361 A1 WO2009096361 A1 WO 2009096361A1
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Prior art keywords
ray
information
air correction
subject
measurement
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PCT/JP2009/051199
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English (en)
Japanese (ja)
Inventor
Ryo Yoshida
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Hitachi Medical Corporation
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Priority to JP2009551510A priority Critical patent/JP5406047B2/ja
Publication of WO2009096361A1 publication Critical patent/WO2009096361A1/fr

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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/10—Scattering devices; Absorbing devices; Ionising radiation filters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/06—Diaphragms

Definitions

  • the present invention relates to an X-ray CT apparatus that images and displays a living tissue of a subject. More specifically, the present invention relates to an X-ray CT apparatus that uses a combination of a plurality of compensation filters and soft line removal filters, performs image correction, and images a subject.
  • An X-ray CT (Computed Tomography) device is a device that captures a tomographic image of a living tissue of a subject and displays it on a display device.
  • the X-ray detector of the X-ray CT apparatus acquires the X-ray dose irradiated from the X-ray tube and transmitted through the subject as projection data.
  • the image processing apparatus of the X-ray CT apparatus performs a predetermined correction process on the acquired projection data, performs image reconstruction, and displays a tomographic image on the display apparatus.
  • the X-ray CT apparatus requires air correction in order to correct variations in sensitivity characteristics of the X-ray detection elements constituting the X-ray detector.
  • the operator performs air measurement to measure air in a state where the subject is not in the scanner of the X-ray CT apparatus before performing the main measurement for imaging the subject.
  • Various corrections offset correction, logarithmic conversion, etc. are performed on the projection data at the time of air measurement and stored as air correction data.
  • air correction data is stored for each element. For example, in the case of a multi-slice X-ray detector having I channels in the channel direction and J columns in the slice direction, I ⁇ J air correction data is stored.
  • air correction data varies depending on tube voltage and collimation
  • the image processing device of the X-ray CT apparatus performs various corrections (offset correction, logarithmic conversion, etc.) on the projection data obtained by imaging the subject, and then performs air correction using the stored air correction data. Do.
  • the image processing apparatus further performs a predetermined correction on the projection data after the air correction, and then performs an image reconstruction process.
  • air measurement is routinely performed after warming up the X-ray tube after starting the X-ray CT apparatus, and the air correction data is updated.
  • various filters are installed between the X-ray tube and the subject.
  • the compensation filter adjusts the intensity distribution of the X-rays incident on the subject
  • the soft line removal filter removes soft rays in the low energy region of the X-rays incident on the subject.
  • the transmission length of the X-ray at the center of the human body is longer than the transmission length of the peripheral portion.
  • the compensation filter is made of a material such as aluminum or Teflon (registered trademark).
  • the cross-section of the object to be imaged by the X-ray CT apparatus is not limited to an ellipse such as a chest to abdomen, but may be a nearly circular shape such as a head.
  • X-ray CT apparatuses provided with several types of compensation filters having different shapes and materials because the size of the subject itself varies from patient to patient, even from the same ellipse or circle, from infants to adults.
  • a compensation filter capable of changing the cross-sectional shape of the X-ray absorption portion into various shapes by using a movable means (see “Patent Document 1”).
  • a soft wire removal filter having a uniform thickness in the X-ray incident direction may be used in combination with the compensation filter.
  • the soft wire removal filter is made of a material such as copper.
  • An invention has been proposed that includes several types of soft wire removal filters having different thicknesses and materials depending on the imaging region and size (see “Patent Document 2”).
  • JP 2005-34173 A Japanese Patent Laid-Open No. 2002-102217
  • the present invention has been made in view of such problems, and an object of the present invention is to provide an X-ray CT apparatus that can speed up daily air measurement and reduce air measurement burden. is there.
  • the present invention for achieving the above-described object includes an X-ray tube that emits X-rays, an X-ray detector that is installed at a position facing the X-ray tube and detects X-rays, and the X-ray tube.
  • a plurality of filters that are installed between the X-ray detector and adjust the intensity of X-rays incident on the subject, a data acquisition circuit that collects projection data from the X-ray detector, and a data acquisition circuit that collects the data
  • the image processing unit performs air measurement for all combinations of the filters during initial setting.
  • the initial air correction information measuring means for measuring the initial air correction information and the initial air correction information measured, and the initial air correction information for all the combinations of the filters with respect to the reference filter combination.
  • a relative information calculation means for calculating relative information of the correction information and storing it in the storage device, and at a predetermined timing during normal time, the reference air correction information is obtained by performing the air measurement on the reference filter combination.
  • Reference normal air correction information measuring means for measuring, and calculating the normal air correction information by expanding the measured reference normal air correction information for all the combinations of the filters using the calculated relative information, and storing the information.
  • the plurality of filters may include a plurality of compensation filters that adjust the intensity distribution of the X-rays incident on the subject, and a soft line removal filter that removes soft rays in the low energy region of the X-rays incident on the subject.
  • Each of the plurality of compensation filters and the soft wire removal filter is installed so that it can be used or not used.
  • the initial setting is assumed when the X-ray CT apparatus is shipped or maintained.
  • Air measurement is measurement in a state where the subject is not in the scanner of the X-ray CT apparatus, and air projection data is obtained by air measurement.
  • the predetermined timing at the normal time is a timing after warm-up of the X-ray tube after starting the X-ray CT apparatus.
  • the X-ray CT apparatus of the present invention measures initial air correction information by performing air measurement for a combination of all the filters that adjust the intensity of X-rays incident on the subject at the time of initial setting.
  • the X-ray CT apparatus calculates the relative information of the initial air correction information with respect to the reference filter combination for all filter combinations, and stores the information in the storage device.
  • the X-ray CT apparatus measures the reference normal air correction information by performing air measurement on the reference filter combination at a predetermined timing during normal operation.
  • the X-ray CT apparatus develops the reference normal air correction information for all combinations of filters using the relative information, calculates the normal air correction information, and holds it in the storage device.
  • the X-ray CT apparatus corrects the collected projection data of the subject using normal air correction information corresponding to the combination of filters used at the time of imaging.
  • the X-ray CT apparatus measures measurement information of a specific channel where X-rays do not pass through the subject during measurement of the subject, and relative information of the measurement information with respect to the reference normal air correction information (first relative information) for the specific channel Is calculated.
  • the X-ray CT device compares the relative information calculated for the specific channel (first relative information) with the relative information read from the storage device (second relative information), and warns or notifies based on the comparison result May be performed.
  • the specific channel may be a channel located at the end of the X-ray detector.
  • an X-ray CT apparatus capable of accelerating daily air measurement and reducing the air measurement burden.
  • Configuration diagram of X-ray CT system 1 Diagram showing around the collimator case 17 Diagram showing soft wire removal filter 41 and compensation filters 45-0 to 45-2 Diagram showing types of compensation filters 45-0 to 45-2 Flow chart showing relative information calculation processing The figure which shows the calculation result of relative information Flow chart showing air correction information calculation processing The figure which shows an air correction information calculation process Flow chart showing measurement processing of subject 19 Flow chart showing monitoring of air correction value Diagram showing reference channel 55 of X-ray detector 25
  • FIG. 1 is a configuration diagram of the X-ray CT apparatus 1.
  • the X-ray CT apparatus 1 is an apparatus that irradiates the subject 19 with X-rays, acquires the X-ray dose transmitted through the subject 19 as projection data, performs image processing, and displays a tomographic image on the display device 13.
  • the X-ray CT apparatus 1 includes an X-ray tube 15, a collimator case 17, an X-ray detector 25, a scanner 3 equipped with a data acquisition circuit 27, a bed 21 on which an object 19 is placed, an input device 11, a display device 13, and scanner control
  • the device 29 includes an image processing device 31, a memory 7, a storage device 9, a system control device 10, and the like.
  • the X-ray tube 15 irradiates the subject 19 with X-rays by applying a high voltage.
  • the collimator case 17 stores a filter for adjusting the X-ray intensity, a collimator for determining the X-ray beam width, and the like (details will be described later).
  • the X-ray detector 25 detects X-rays transmitted through the subject 19 and converts them into electric signals.
  • the data collection circuit 27 collects projection data detected by the X-ray detector 25.
  • the scanner 3 has an X-ray tube 15 and an X-ray detector 25 arranged opposite to each other with the subject 19 interposed therebetween, and has a rotation mechanism that rotates around the subject 19 and the bed 21 on which the subject 19 is placed.
  • the input device 11 is a device such as a keyboard, a mouse, a trackball, a touch panel, and a button arranged in the X-ray CT apparatus 1.
  • the operator operates the input device 11 to perform an imaging instruction, measurement operation instruction, parameter setting, input, and the like by the X-ray CT apparatus 1.
  • the display device 13 is a CRT, a liquid crystal display device, or the like, and displays the result of image processing by the image processing device 31.
  • the scanner control device 29 controls the X-ray tube 15, the filter and collimator in the collimator case 17, and the X-ray detector 25. For example, the scanner control device 29 performs switching control between a plurality of compensation filters and soft line removal filters in the collimator case 17.
  • the image processing device 31 performs image processing of projection data collected by the data collection circuit 27 of the scanner 3.
  • the image processing device 31 includes a data acquisition unit 32 that acquires the projection data collected by the data collection circuit 27, a correction processing unit 33 that performs various correction processes of the projection data, and an image that reconstructs a cross-sectional image from the projection data after the correction process.
  • Reconfiguration processing means 35 is provided.
  • the correction processing includes air correction, offset correction, reference correction, beam hardening correction, non-linear correction, and the like.
  • the memory 7 is a semiconductor storage device such as a RAM and a ROM.
  • the storage device 9 is a storage device such as a hard disk.
  • the storage device 9 includes storage units such as an initial air correction information storage unit 36, a relative information storage unit 37, a normal air correction information storage unit 38, and a measurement information storage unit 39.
  • the initial air correction information storage unit 36 is a storage unit for air correction information that is measured for all combinations of compensation filters and soft wire removal filters when the X-ray CT apparatus 1 is shipped or maintained.
  • the relative information storage unit 37 is a storage unit for the relative information of the air correction information of all the filter combinations calculated based on the air correction information based on the reference filter combination.
  • the normal air correction information storage unit 38 is a storage unit for air correction information calculated for all combinations of compensation filters and soft line removal filters.
  • the normal air correction information storage unit 38 is calculated using air correction information and relative information based on a combination of filters that are measured on a daily basis.
  • the measurement information storage unit 39 is a storage unit for projection data of the subject 19 that is corrected using normal air correction information.
  • the system controller (CPU) 10 controls the entire system of the X-ray CT apparatus 1.
  • FIG. 2 is a view showing the vicinity of the collimator case 17.
  • a soft wire removal filter moving means 43 for switching the soft wire removal filter 41, a collimator 48, and the like are disposed.
  • the irradiated X-rays 23 exposed from the X-ray tube 15 pass through the soft-wire removal filter 41 to remove soft rays in the low-energy region of the X-ray, and pass through the compensation filter 45 so that the X-ray intensity distribution is reduced.
  • the X-ray width is adjusted by the collimator 48 and the subject 19 is irradiated.
  • the X-rays emitted from the X-ray tube 15 are transmitted in the order of the soft line removal filter 41 and the compensation filter 45, but are not limited to this order, and are in the order of the compensation filter 45 and the soft line removal filter 41. May be installed.
  • FIG. 3 is a diagram showing the soft line removal filter 41 and the compensation filters 45-0 to 45-2.
  • the soft wire removal filter 41 When the soft wire removal filter 41 is used, it is disposed on the X axis through which the irradiation X-rays 23 are transmitted.
  • the soft wire removal filter moving means 43 When the soft wire removal filter 41 is not used, the soft wire removal filter moving means 43 is used to move in the Z-axis direction off the axis.
  • the soft wire removal filter 41 is used to prevent invalid exposure of the subject 19.
  • a soft wire removal filter 41 is used.
  • the beam hardening effect is that low-energy X-rays are selectively absorbed and the detected X-rays have high energy.
  • the soft line removal filter 41 may not be used when imaging a region near the abdominal liver that is difficult to contrast. .
  • a plurality of compensation filters 45-0 to 45-2 are installed along the Z-axis direction, which is the body axis direction of the subject 19.
  • the operator selects the compensation filter 45 to be used from among the compensation filters 45-0 to 45-2 according to the imaging region and size of the subject 19, and the compensation filter 45 selected using the compensation filter moving means 47. Is moved in the Z-axis direction and installed on the X-axis through which the irradiated X-rays 23 are transmitted.
  • FIG. 4 is a diagram showing the shape types of the compensation filters 45-0 to 45-2.
  • the compensation filter 45-1 has the largest curvature of the curved surface, and the compensation filter 45-0 and the compensation filter 45-2 have a curvature of curvature smaller than that.
  • the compensation filter 45-1 is used when imaging a relatively small subject 19, such as the head, heart, or child, and the compensation filter 45-0 is used for the subject 19 such as a chest or a standard size abdomen,
  • the compensation filter 45-2 is used for imaging the abdomen of the subject 19 having a large size.
  • the compensation filter 45-0 of size M the compensation filter C 0 as a reference.
  • the compensation filter 45-1 S size and the compensation filter C 1 the compensation filter 45-2 L size and the compensation filter C 2.
  • the subject 19 is imaged by the X-ray CT apparatus 1 in which the compensation filter 45 and the soft line removal filter 41 are combined, depending on the imaging region and size of the subject 19.
  • FIG. 5 is a flowchart showing a relative information calculation process at the time of initial setting.
  • the initial setting is before shipment of the X-ray CT apparatus 1 or during regular maintenance.
  • the combination of the compensation filter 45 and the soft line removal filter 41 is represented as (C m , F n ).
  • the subscript “m” of “C” indicates the shape of the compensation filter 45 to be used.
  • the subscript “n” of “F” indicates whether or not the soft line removal filter 41 is used.
  • the soft wire removal filter 41 0”
  • the soft wire removal filter 41 1”.
  • An operator (physician or engineer) inputs a command for air measurement at the time of initial setting to the input device 11, and performs air measurement for all combinations (C m , F n ) of the compensation filter 45 and the soft wire removal filter 41.
  • the air correction data is acquired by the data acquisition means 32 (step 1001).
  • the air measurement is performed in a state where the subject 19 is not in the scanner of the X-ray CT apparatus 1.
  • the system control device 10 When the measurement of the air correction data is completed, the system control device 10 performs offset correction and reference correction on the air correction data acquired by the correction processing means 33 (step 1002).
  • the offset correction is correction for canceling the dark current components of the X-ray detector 25 and the data acquisition circuit 27.
  • Reference correction is correction that cancels fluctuations in X-rays during and after scanning.
  • the air correction data after the offset correction and the reference correction is stored as initial air correction data AIr0 [(C m , F n )] in the initial air correction information storage unit 36 of the storage device 9 (step 1003).
  • the air correction data is actually data acquired for each channel and each projection angle of the X-ray detector 25.
  • the system controller 10 sets the relative data Trans [(C for the reference initial data AIr0 [(C 0 , F 0 )] as the reference for all the initial air correction data AIr0 [(C m , F n )]. m , F n )] is calculated (step 1004).
  • Trans [(C m , F n )] is calculated by the equation (1).
  • Trans [(C m, F n )] AIr0 [(C m, F n)] - AIr0 [(C 0, F 0)] ⁇ (1)
  • the initial air correction data AIr0 [(C 0 , F 0 )] is the reference initial data AIr0 [(C 0 , F 0 )] as a reference, and therefore the relative data Trans [(C 0 , F 0 )] is “0”.
  • the relative data Trans [(C m , F n )] is the initial air correction data AIr0 [(C m , F n )] and the reference initial data AIr0 [(C 0 , F 0 ), respectively.
  • the calculation formula is not limited to the calculation of the difference. Division or other relative data calculation formulas may be used.
  • the calculated relative data Trans [(C m , F n )] is stored in the relative information storage unit 37 of the storage device 9 (step 1005).
  • FIG. 6 is a diagram illustrating a calculation result of relative information.
  • FIGS. 6 (a) to 6 (c) are graphs showing the initial air correction information acquired in the process of step 1003.
  • the horizontal axis of this graph is the channel 49 of the X-ray detector 25, and the vertical axis is the X-ray detector output 51.
  • the graph 201, the graph 203, and the graph 205 indicate the initial air correction information acquired when the soft line removal filter 41 is used (F 0 ).
  • the graph 202, the graph 204, and the graph 206 show the initial air correction information acquired when the soft line removal filter 41 is not used (F 1 ).
  • FIG. 6 (d) to FIG. 6 (f) are graphs showing the relative information calculated in the process of step 1004.
  • the horizontal axis of this graph is the channel 49 of the X-ray detector 25, and the vertical axis is the relative data 53.
  • the relative information graphs 301 to 306 are calculated based on the initial air correction information graphs 201 to 206 in the processing of step 1004, respectively.
  • FIG. 7 is a flowchart showing a normal air correction information calculation process.
  • the normal time is, for example, the timing after warm-up of the X-ray tube after the daily X-ray CT apparatus 1 is started.
  • the operator inputs a command to the input device 11 at a predetermined timing before the start of the CT examination, and measures the air for the combination of the compensation filter 45 (C 0 ) and the soft wire removal filter 41 (F 0 ). To obtain air correction data (step 2001).
  • the correction processing means 33 performs offset correction and reference correction on the acquired air correction data (step 2002).
  • the air correction data after the offset correction and the reference correction is stored in the storage device 9 as reference normal data AIr1 [(C 0 , F 0 )] (step 2003).
  • the system control device 10 compares the measured reference normal data AIr1 [(C 0 , F 0 )] and the relative information (relative data Trans [(C m , F n )]), the normal air correction data AIr1 [(C m , F n )] is calculated for all combinations (C m , F n ) of the compensation filter 45 and the soft line removal filter 41. (Step 2004).
  • AIr1 [(C m , F n )] The normal air correction data AIr1 [(C m , F n )] is calculated by equation (2).
  • AIr1 [(C m , F n )] Trans [(C m , F n )] + AIr1 [(C 0 , F 0 )] (2)
  • the normal air correction data AIr1 [(C m , F n )] is the relative data Trans [(C m , F n )] and the reference normal data AIr1 [(C 0 , F 0 ), respectively.
  • the calculation formula is not limited to addition. A calculation formula corresponding to the calculation formula of the relative data used in the processing of step 1004 may be used.
  • the system control device 10 performs logarithmic conversion on the calculated normal air correction data AIr1 [(C m , F n )] (step 2005) and stores it in the normal air correction information storage unit 38 of the storage device 9 (step 2006). ).
  • FIG. 8 is a diagram showing the air correction information calculation process (FIG. 7: Step 2004) and the result.
  • the relative information graphs 301 to 306 in FIG. 8 are the same as the relative information graphs 301 to 306 in FIG. 6, and are calculated by the processing in step 1004.
  • the horizontal axis of the normal air correction information graph is the channel 49 of the X-ray detector 25, and the vertical axis is the incident X-ray intensity 54. Since the incident X-ray intensity 54 in FIG. 8 is a calculated value, it is distinguished from the X-ray detector output 51 in FIG. 6 which is an actual measurement value.
  • the reference normal data graph 401 is obtained by the processing in step 2003.
  • the normal air correction information graphs 401 to 406 are calculated from the relative information graphs 301 to 306 and the reference normal data graph 401 in the process of step 2004, respectively.
  • FIG. 9 is a flowchart showing measurement of the subject 19 and air correction.
  • the operator selects a compensation filter 45C p (p is 0, 1, or 2) and a soft line removal filter 41F q (q is either 0 or 1) corresponding to the imaging region of the subject 19 and the size of the subject 19. ) Is selected.
  • the selected compensation filter 45 and soft line removal filter 41 are set on the X axis in FIG. In this state, a CT scan of the subject 19 is performed, and the measurement data Data0 [(C p , F q )] is acquired by the data acquisition means 32 (step 3001).
  • the correction processing means 33 performs offset correction and reference correction on the acquired measurement data Data0 [(C p , F q )] (step 3002). From the normal air correction information stored in the normal air correction information storage unit 38 of the storage device 9, the correction processing means 33 calculates normal air corresponding to the combination (C p , F q ) of the compensation filter 45 and the soft wire removal filter 41.
  • the correction data AIr1 [(C p , F q )] is read and the air correction of the measurement data Data 0 [(C p , F q )] is performed to obtain the measurement data Data 1 [(C p , F q )] (step 3003 ).
  • the correction processing means 33 performs various corrections such as beam hardening correction and nonlinear correction on the calculated measurement data Data1 [(C p , F q )] (step 3004), and the corrected measurement data Data1 [(C p , F q )] is stored in the measurement data storage unit 39 of the storage device 9 (step 3005).
  • the image reconstruction processing means 35 of the X-ray CT apparatus 1 performs image reconstruction processing based on the corrected measurement data Data1 [(C p , F q )] (step 3006).
  • the X-ray CT apparatus 1 performs air measurement for all combinations (C m , F n ) of the compensation filter 45 and the soft wire removal filter 41 to obtain initial air correction information, Relative information for the reference combination (C 0 , F 0 ) is calculated and held.
  • X-ray CT apparatus 1 is in the normal, at a predetermined timing, the only combination that serves as a reference of the compensation filter 45 and the soft wire removal filter 41 (C 0, F 0) performs air measurement, a combination of (C 0, F 0) Based on the air measurement data and the relative information, normal air correction information is calculated for all combinations (C m , F n ) of the compensation filter 45 and the soft wire removal filter 41.
  • the X-ray CT apparatus 1 reads normal air correction information corresponding to the combination (C p , F q ) of the used compensation filter 45 and soft line removal filter 41, and measures the X-ray projection of the measured subject. Perform air correction on the data.
  • the X-ray CT apparatus 1 includes a plurality of filters, it is only necessary to perform air measurement for the reference combination (C 0 , F 0 ) at normal times. Work burden on the person can be reduced.
  • the X-ray CT apparatus 1 holds normal air correction information for all combinations (C m , F n ), and performs air correction according to the combination of filters used when measuring the subject. It is not necessary to acquire the air correction data every time the combination is changed. Further, the exposure of the subject can be reduced by selecting a plurality of compensation filters and soft line removal filters suitable for the imaging region of the subject and the size of the subject.
  • FIG. 10 is a flowchart showing an air correction value monitoring process.
  • the system control device 10 performs the measurement process of the subject 19 (FIG. 9) (step 4001), refers to the measurement information stored in the measurement information storage unit 39 of the storage device 9 at a predetermined timing, and performs a reference
  • the measurement data Refch ⁇ Data 0 [(C p , F q )] ⁇ of channel 55 is acquired (step 4002).
  • FIG. 11 is a diagram showing the reference channel 55 of the X-ray detector 25.
  • the reference channels 55-1 and 55-2 shown in FIG. 11 are arranged at positions exposed to X-rays (direct X-rays) that do not pass through the subject 19 when the subject 19 is measured. Accordingly, it can be considered that the air measurement is performed in the reference channels 55-1 and 55-2 simultaneously with the normal measurement of the subject 19. Therefore, the measurement data Refch ⁇ Data0 [(C p, F q)] ⁇ can be considered normal air correction data Refch ⁇ AIr1 [(C p, F q)] ⁇ and.
  • the reference channel 55 of the X-ray detector 25 shown in FIG. 11 is basically arranged at a position where data transmitted through the subject 19 does not enter, but the size of the subject 19 is very large, and the reference channel 55 When data transmitted through the subject 19 enters the channel 55, the measurement data Refch ⁇ Data0 [(C p , F q )] ⁇ is not used for monitoring the air correction value.
  • the system control device 10 refers to the normal air correction information stored in the normal air correction information storage unit 38 of the storage device 9, and from the reference normal data AIr1 [(C 0 , F 0 )], Reference normal data Refch ⁇ AIr1 [(C 0 , F 0 )] ⁇ of the reference channel 55 is acquired (step 4003).
  • the difference value X1 is calculated by equation (3).
  • the system control device 10 uses the relative information stored in the relative information storage unit 37 of the storage device 9 to the combination (C p , F q ) of the compensation filter 45 and the soft wire removal filter 41 used during the CT scan.
  • Corresponding relative data Refch ⁇ Trans [(C p , F q )] ⁇ in the reference channel 55 at the time of initial setting is read out to obtain the following X2 (step 4005).
  • the difference value X2 is expressed by equation (4).
  • the difference value X2 is a difference value between the initial air correction data AIr0 [(C p , F q )] and the reference initial data AIr0 [(C 0 , F 0 )] in the reference channel 55 at the time of initial setting.
  • the system control device 10 compares the difference value X1 with the difference value X2, and determines whether or not the comparison result exceeds the threshold value T (step 4006).
  • the ratio X1 / X2 between the difference value X1 and the difference value X2 is compared with the threshold value T. If the ratio X1 / X2 does not exceed the threshold T (NO in step 4006), the process returns to the measurement process of the subject 19 and the air data comparison process (step 4001).
  • the system control device 10 re-reads “Please perform all air measurements” on the display device 13 when the scan of the subject 19 is completed.
  • a warning display for prompting measurement is performed (step 4007).
  • the difference between the difference value X1 and the difference value X2 increases, the relative information stored in the relative information storage unit 37 differs from the actual value, and the accuracy of air correction deteriorates.
  • the operator who has confirmed the warning display performs air measurement for all combinations of the compensation filter 45 and the soft wire removal filter 41 provided in the X-ray CT apparatus 1 and updates the relative information.
  • the remote maintenance function of the X-ray CT apparatus 1 may be used to notify the management facility (such as a service center) of the X-ray CT apparatus 1 that X1 / X2 exceeds the threshold value T (step 4008).
  • the X-ray CT apparatus 1 uses the air data of the reference channel 55 simultaneously with the measurement of the subject 19, and monitors the deviation of the relative information used for air correction from the actual measurement data.
  • the second embodiment As described above, in the second embodiment, as in the first embodiment, it is only necessary to perform air measurement for the reference combination (C 0 , F 0 ) at the normal time. Therefore, the operator's work load related to air measurement is reduced. It can be reduced. In the second embodiment, it is determined whether it is necessary to recalculate the calculated relative information by monitoring the deviation between the relative information already calculated for use in air correction and the actual measurement value. Therefore, it is possible to appropriately determine the maintenance timing.

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  • Apparatus For Radiation Diagnosis (AREA)

Abstract

L'invention porte sur un appareil de tomodensitométrie permettant d'accélérer une mesure quotidienne de l'air et de faciliter ladite mesure de l'air. Au moment du réglage initial de l'appareil de tomodensitométrie (1), des mesures d'air sont effectuées pour acquérir des données de correction par rapport à l'air initial, pour toutes les combinaisons d'une pluralité de filtres, aux fins d'ajuster l'intensité des rayons X incidents sur un sujet (19). Pour lesdites combinaisons de tous les filtres, les données relatives aux données de correction par rapport à l'air initial, pour une combinaison de filtres de référence, sont calculées puis conservées dans un dispositif de stockage (9). À un moment dit ordinaire, une mesure de l'air est effectuée dans la combinaison de filtres de référence, pour obtenir la mesure des données de correction par rapport à l'air ordinaire de référence. Les données relatives sont utilisées pour étendre à l'ensemble des combinaisons de filtres les données de correction par rapport à l'air ordinaire de référence, et ainsi calculer les données de correction relatives à l'air ordinaire. Les données projetées d'un sujet (19), mesurées par l'appareil de tomodensitométrie (1), sont corrigées en ce qui concerne l'air, à l'aide des données de correction par rapport à l'air ordinaire.
PCT/JP2009/051199 2008-01-28 2009-01-26 Appareil de tomodensitométrie WO2009096361A1 (fr)

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JP2011139786A (ja) * 2010-01-07 2011-07-21 Hitachi Medical Corp Ｘ線ｃｔ装置
JP2011250884A (ja) * 2010-05-31 2011-12-15 Toshiba Corp Ｘ線診断装置及びキャリブレーションデータ保管システム
CN105054959A (zh) * 2015-08-12 2015-11-18 沈阳东软医疗系统有限公司 空气校正方法、装置及设备
CN111436194A (zh) * 2018-11-13 2020-07-21 西安大医集团股份有限公司 滤光器、放射线扫描装置及放射线扫描方法
CN111728632A (zh) * 2020-07-31 2020-10-02 上海联影医疗科技有限公司 射线探测装置、射线探测方法和ct图像重建方法
JP2020202959A (ja) * 2019-06-17 2020-12-24 株式会社日立製作所 Ｘ線ｃｔ装置
US11096642B2 (en) 2019-08-16 2021-08-24 GE Precision Healthcare LLC Methods and systems for X-ray tube conditioning
US11147528B2 (en) 2019-08-16 2021-10-19 GE Precision Healthcare LLC Methods and systems for X-ray tube conditioning
US11160518B2 (en) 2019-08-16 2021-11-02 GE Precision Healthcare LLC Methods and systems for integrated filter system
US12125604B2 (en) 2022-02-02 2024-10-22 GE Precision Healthcare LLC Pre-patient collimator having a built-in alignment mechanism

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JP2011139786A (ja) * 2010-01-07 2011-07-21 Hitachi Medical Corp Ｘ線ｃｔ装置
JP2011250884A (ja) * 2010-05-31 2011-12-15 Toshiba Corp Ｘ線診断装置及びキャリブレーションデータ保管システム
CN105054959A (zh) * 2015-08-12 2015-11-18 沈阳东软医疗系统有限公司 空气校正方法、装置及设备
CN105054959B (zh) * 2015-08-12 2018-06-15 沈阳东软医疗系统有限公司 空气校正方法、装置及设备
US10238360B2 (en) 2015-08-12 2019-03-26 Shenyang Neusoft Medical Systems Co., Ltd. Air calibration
CN111436194A (zh) * 2018-11-13 2020-07-21 西安大医集团股份有限公司 滤光器、放射线扫描装置及放射线扫描方法
JP7350527B2 (ja) 2019-06-17 2023-09-26 富士フイルムヘルスケア株式会社 Ｘ線ｃｔ装置
JP2020202959A (ja) * 2019-06-17 2020-12-24 株式会社日立製作所 Ｘ線ｃｔ装置
US11096642B2 (en) 2019-08-16 2021-08-24 GE Precision Healthcare LLC Methods and systems for X-ray tube conditioning
US11147528B2 (en) 2019-08-16 2021-10-19 GE Precision Healthcare LLC Methods and systems for X-ray tube conditioning
US11160518B2 (en) 2019-08-16 2021-11-02 GE Precision Healthcare LLC Methods and systems for integrated filter system
US11712216B2 (en) 2019-08-16 2023-08-01 GE Precision Healthcare LLC Methods and systems for x-ray tube conditioning
CN111728632B (zh) * 2020-07-31 2023-08-15 上海联影医疗科技股份有限公司 射线探测装置、射线探测方法和ct图像重建方法
CN111728632A (zh) * 2020-07-31 2020-10-02 上海联影医疗科技有限公司 射线探测装置、射线探测方法和ct图像重建方法
US12125604B2 (en) 2022-02-02 2024-10-22 GE Precision Healthcare LLC Pre-patient collimator having a built-in alignment mechanism
JP7657840B2 (ja) 2022-02-02 2025-04-07 ジーイー・プレシジョン・ヘルスケア・エルエルシー アライメント機構を内蔵した前置コリメータ。

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