JP2006034306A - Radiographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce time required for calibration, to improve the utilization efficiency of an apparatus and to improve operability. <P>SOLUTION: Radiographic apparatus is provided with a calibration scanning condition setting part 54 for setting a calibration scanning condition on the basis of the execution frequency of a main scanning condition stored in a storage device 33 and executes calibration scanning on the basis of the calibration scanning condition set by the calibration scanning condition setting part 54. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation imaging apparatus.

  As a radiation imaging apparatus, an X-ray CT (Computed Tomography) apparatus that generates an image of a tomographic plane of a subject using X-rays that are radiation is known. An X-ray CT apparatus uses a human body or an object as a subject, and is used in a wide range of applications such as medical use and industrial use.

  During the main scan for capturing a tomographic image of the subject, the X-ray CT apparatus irradiates X-rays from a plurality of view directions with the slice thickness direction of the subject as an axis, and subjects the subject to each view direction. X-rays that pass through are detected by an X-ray detector to generate projection data. Then, the X-ray CT apparatus reconstructs the generated projection data by, for example, a filtered back projection method, and generates a tomographic image of the subject. In the main scan, various conditions of the main scan are set according to the imaging region.

  Incidentally, the X-ray detector of the X-ray CT apparatus has a plurality of detection elements formed in an array. The detection elements constituting the X-ray detector have different characteristics such as detection sensitivity, and vary. For this reason, the projection data of the subject includes variations in the characteristics of the X-ray detector. Therefore, when reconstructing the projection data as it is, ring artifacts are included in the reconstructed image. The image quality is degraded.

Therefore, in order to prevent deterioration in image quality, before performing the main scan, a calibration scan is performed to generate calibration data for correcting variation in characteristics between detection elements of the X-ray detector. (For example, refer to Patent Document 1).
JP 2001-70297 A

  When performing a calibration scan, the X-ray detector emits X-rays from the X-ray tube to a reference set object such as air or phantom based on the calibration scan conditions, and the X-ray detector detects the X-rays from the X-ray tube. To detect. Then, calibration data for calibrating the characteristics of the X-ray detector is generated based on the X-rays detected under the calibration scan condition.

  Thereafter, the projection data of the subject is calibrated based on the generated calibration data, and the calibrated projection data is reconstructed to generate a tomographic image of the subject.

  Conventionally, the above-described calibration scan is performed under calibration scan conditions that can handle all the main scan conditions because the main scan conditions can be set under various conditions depending on the imaging region. For example, when the main scan can be performed at the X-ray tube voltages of 100 kV and 120 kV, the calibration scan condition is set so as to include both the X-ray tube voltages of 100 kV and 120 kV.

  However, at the imaging site where the main scan of the subject is performed, the main scan is rarely performed under all settable main scan conditions. For example, in the medical field in which a predetermined affected area is treated professionally, the main scan condition that is optimal for the imaging of the affected area that is the specialty is often repeatedly performed, and the frequency of performing each main scan condition is often There are many different cases.

  For this reason, when calibration is performed under calibration scan conditions that are compatible with all main scan conditions, the calibration scan is performed under calibration scan conditions including conditions that are not performed. Specifically, for example, even when only the condition of the tube voltage 100 kV of the X-ray tube is performed in the main scan, if the apparatus can perform the main scan of the tube voltages 100 kV and 120 kV, Calibration scan conditions are set and implemented to include both 100 kV and 120 kV. For this reason, conventionally, as the main scan condition, for example, even when the tube voltage of 100 kV is small, it is set as the calibration scan condition, the time required for calibration is increased, and the use efficiency of the apparatus is increased. The operability is lowered. In particular, in recent years, as the number of detection elements of the X-ray detector increases to realize multi-slice, the time required for calibration has increased remarkably, and the use efficiency of the apparatus has been significantly reduced.

  Accordingly, an object of the present invention is to provide a radiation imaging apparatus capable of reducing the time required for calibration, improving the utilization efficiency of the apparatus, and improving the operability.

  In order to achieve the above object, the radiation imaging apparatus of the present invention calibrates the characteristics of the detection means for detecting the radiation by performing a calibration scan for irradiating the reference setting object with radiation based on the calibration scan condition. Calibration data is generated, and radiation detected based on the main scanning condition and transmitted through the subject is detected by the detection means, and projection data of the subject is collected, and based on the calibration data, the calibration data is collected. A radiographic apparatus that calibrates projection data and generates an image of the subject based on the calibrated projection data, a main scan condition setting unit that sets the main scan condition, and the main scan condition setting Storage means for storing an execution frequency for the main scan condition set by the means, and the storage means Calibration scan setting means for setting the calibration scan condition based on the frequency of execution of the main scan condition stored in the storage, and based on the calibration scan condition set by the calibration scan condition setting means The calibration scan is performed.

  According to the radiographic apparatus of the present invention described above, the main scan condition is set by the main scan condition setting unit, and the execution frequency for the main scan condition set by the main scan condition setting unit is stored by the storage unit. Then, the calibration scan setting unit sets the calibration scan condition based on the execution frequency of the main scan condition stored in the storage unit. Then, the calibration scan is performed based on the calibration scan condition set by the calibration scan condition setting means.

  Therefore, according to the present invention, it is possible to provide a radiation imaging apparatus that can reduce the time required for calibration, improve the utilization efficiency of the apparatus, and improve the operability.

  Embodiments according to the present invention will be described below.

  FIG. 1 is a block diagram showing an overall configuration of an X-ray CT apparatus 1 as a radiation imaging apparatus according to an embodiment of the present invention, and FIG. 2 shows an X-ray CT as a radiation imaging apparatus according to an embodiment of the present invention. 2 is a configuration diagram showing a main part of the device 1. FIG.

  As shown in FIG. 1, the X-ray CT apparatus 1 of this embodiment includes a scanning gantry 2, an operation console 3, and an imaging table 4.

  The scanning gantry 2 includes an X-ray tube 20, an X-ray tube moving unit 21, a collimator 22, an X-ray detector 23, a data collection unit 24, an X-ray controller 25, a collimator controller 26, a rotation unit 27, and a rotation controller 28. . Here, the X-ray tube 20 and the X-ray detector 23 are disposed to face each other with the X-ray irradiation space 29 interposed therebetween.

  The X-ray tube 20 is provided for irradiating X-rays. As shown in FIG. 2, the X-ray tube 20 irradiates the imaging region R of the subject 6 with X-rays 5 having a predetermined intensity via the collimator 22 based on a control signal CTL 251 from the X-ray controller 25.

  As shown in FIG. 2, the X-ray tube moving unit 21 determines the radiation center of the X-ray tube 20 based on the control signal CTL 252 from the X-ray controller 25 and the imaging table in the X-ray irradiation space 29 in the scanning gantry 2. 4 is moved in the slice thickness direction z of the subject 6 to be placed.

  As shown in FIGS. 1 and 2, the collimator 22 is disposed between the X-ray tube 20 and the X-ray detector 23. For example, as shown in FIG. 2, the collimator 22 is composed of two plates each provided in the channel direction x and the slice thickness direction z. The collimator 22 independently moves two plates provided in each direction based on a control signal CTL 261 from the collimator controller 26, and blocks the X-rays 5 irradiated from the X-ray tube 20 in each direction. To form a cone, and adjust the irradiation range of the X-ray 5.

  The X-ray detector 23 is provided for detecting X-rays emitted from the X-ray tube 20. For example, as shown in FIG. 2, the X-ray detector 23 includes eight X-ray detection modules 23A, 23B, 23C, 23D, 23E, 23F, 23G, and 23H. Eight X-ray detection modules 23A, 23B, 23C, 23D, 23E, 23F, 23G, and 23H are arranged adjacent to each other in the slice thickness direction z in order from the A column to the H column.

  FIG. 3 is a configuration diagram showing the X-ray detection module 23A in the A column among the eight X-ray detection modules 23A, 23B, 23C, 23D, 23E, 23F, 23G, and 23H constituting the X-ray detector 23. . As shown in FIG. 3, in the X-ray detection module 23A, detection elements 23a for detecting X-rays are arranged in an array in the channel direction x and the slice thickness direction z. The plurality of detection elements 23a arranged two-dimensionally forms an X-ray incident surface curved in a cylindrical concave shape as a whole. Here, for example, 1000 detection elements 23a are arranged in the channel direction x, and for example, eight detection elements 23a are arranged in the slice thickness direction z. Note that the X-ray detection modules 23B, 23C, 23D, 23E, 23F, 23G, and 23H in the B to H columns are the same as the X-ray detection module 23A in the A column shown in FIG.

  The detection element 23a includes, for example, a scintillator (not shown) that converts detected X-rays into light, and a photodiode (not shown) that converts light converted by the scintillator into charges. The X-ray detector 23 includes: It is configured as a solid state detector. The detection element 23a is not limited to this. For example, the detection element 23a is a semiconductor detection element using cadmium tellurium (CdTe) or the like, or an ionization chamber type detection element 23a using xenon (Xe) gas. Good.

  4 and 5 are diagrams showing the interrelationship among the X-ray tube 20, the collimator 22, and the X-ray detector 23. FIG. 4A is a diagram illustrating a state in which the slice thickness direction z is a line of sight, and FIG. 4B is a diagram illustrating a state in which the channel direction x is a line of sight. FIG. 5 is a diagram illustrating a state in which the subject 6 is imaged in a state where the line of sight is the channel direction x as in FIG. 4B.

  As shown in FIGS. 4A and 4B, the X-ray 5 emitted from the X-ray tube 20 is formed into a cone shape by the collimator 22 and irradiated to the X-ray detector 23. As shown in FIG. 5, when imaging the subject 6, the subject 6 is placed on the imaging table 4, and the placed subject 6 is carried into the X-ray irradiation space 29. Then, X-rays 5 are irradiated from a plurality of view directions around the subject 6 with the slice thickness direction z of the subject 6 as an axis, and pass through the subject 6 for each view direction via the collimator 22. The line 5 is detected by the X-ray detector 23 to generate projection data.

  The data collection unit 24 is provided for collecting data based on radiation detected by the X-ray detector 23. For example, as shown in FIG. 2, the data collection unit 24 collects projection data of the subject 6 based on the X-rays 5 detected by the respective detection elements 23a of the X-ray detector 23 under the main scan conditions. To the operation console 3. The data collection unit 24 includes, for example, a selection / addition switching circuit (MUX, ADD) 241 and an analog-digital converter (ADC) 242. The selection / addition switching circuit 241 selects projection data by the detection element 23a of the X-ray detector 23 in accordance with the control signal CTL303 from the central processing unit 30, or adds a combination thereof, and the result is analog- Output to the digital converter 242. The analog-digital converter 242 converts the projection data selected by the selection / addition switching circuit 241 or added in an arbitrary combination from an analog signal to a digital signal and outputs it to the central processing unit 30.

  As shown in FIG. 2, the X-ray controller 25 outputs a control signal CTL 251 to the X-ray tube 20 in accordance with a control signal CTL 301 from the central processing unit 30 to control X-ray irradiation. Further, the X-ray controller 25 outputs a control signal CTL252 to the X-ray tube moving unit 221 in response to the control signal CTL301 from the central processing unit 30, and moves the radiation center of the X-ray tube 20 in the slice thickness direction z. To control.

  As shown in FIG. 2, the collimator controller 26 outputs a control signal CTL 261 to the collimator 22 in response to the control signal CTL 302 from the central processing unit 30 to shape the X-ray 5 emitted from the X-ray tube 20. The collimator 22 is controlled.

  As shown in FIG. 1, the rotating unit 27 rotates in a predetermined direction in response to a control signal CTL 28 from the rotation controller 28. The rotating unit 27 includes an X-ray tube 20, an X-ray tube moving unit 21, a collimator 22, an X-ray detector 23, a data collection unit 24, an X-ray controller 25, and a collimator controller 26. As the rotating unit 27 rotates, the position of the subject 6 carried into the X-ray irradiation space 29 changes. By rotating the rotating unit 27, X-rays 5 are irradiated from a plurality of view directions with the slice thickness direction z of the subject 6 as an axis, and the X-rays 5 transmitted through the subject 6 are detected.

  As shown in FIG. 2, the rotation controller 28 outputs a control signal CTL 28 to the rotation unit 27 in accordance with a control signal CTL 304 from the central processing unit 30 of the operation console 3 and controls the rotation unit 27 to rotate.

  The operation console 3 includes a central processing unit 30, an input device 31, a display device 32, and a storage device 33.

  FIG. 6 is a configuration diagram showing the configuration of the central processing unit 30 of the operation console 3.

  The central processing unit 30 is configured by a computer, for example, and includes a control unit 41 and a data processing unit 51 as shown in FIG. Here, the control unit 41 includes a main scan control unit 42 and a calibration scan control unit 43, and the data processing unit 51 includes a main scan condition setting unit 52, a calibration data generation unit 53, and a calibration. A scan condition setting unit 54, a calibration unit 55, an image generation unit 56, and a warning unit 57 are included.

  The main scan control unit 42 of the control unit 41 irradiates the subject 6 with the X-ray 5 from the X-ray tube 20 based on the main scan condition, and applies the X-ray 5 transmitted through the subject 6 to the X-ray detector 23. In this way, each part is controlled to perform scanning. Specifically, the main scan control unit 42 outputs a control signal CTL 30a to each unit based on the main scan condition to execute the main scan. For example, the main scan control unit 42 outputs a control signal CTL 30 b to the imaging table 4 and causes the imaging table 4 to be carried into or out of the X-ray irradiation space 29 of the scanning gantry 2. Further, the main scan control unit 42 outputs a control signal CTL 304 to the rotation controller 28 to rotate the rotation unit 27 of the scanning gantry 2. Further, the main scan control unit 42 outputs a control signal CTL 301 to the X-ray controller 25 so that the X-ray tube 20 emits the X-ray 5. Then, the main scan control unit 42 outputs the control signal CTL 302 to the collimator controller 26 and controls the collimator 22 to shape the X-ray 5. Further, the main scan control unit 42 outputs a control signal CTL 303 to the data collection unit 24 and controls to collect projection data obtained by the detection element 23 a of the X-ray detector 23. In the present embodiment, the main scan control unit 42 performs scanning based on the main scan conditions set by the main scan condition setting unit 52.

  The calibration scan control unit 43 irradiates the X-ray 5 from the X-ray tube 20 to a reference set object such as air or phantom based on the calibration scan condition, and the X-ray detector 23 X-rays from the X-ray tube 20. Scanning is performed by controlling each unit so as to detect 5. In the present embodiment, the calibration scan control unit 43 performs scanning based on the calibration scan conditions set by the calibration scan condition setting unit 54.

  The main scan condition setting unit 52 of the data processing unit 51 sets the main scan condition based on a command such as an imaging method of the subject 6 input from the input device 31 by the operator. The history of the main scanning conditions set by the main scanning condition setting unit 52 is stored in the storage device 33 described later.

  The calibration data generation unit 53 generates calibration data for calibrating characteristics such as detection sensitivity of the X-ray detector 23 based on the X-rays detected under the calibration scan condition.

  The calibration scan condition setting unit 54 sets the calibration scan condition based on the execution frequency of the main scan condition stored in the storage device 33 described later. For example, the calibration scan condition setting unit 54 sets the calibration scan condition so as to correspond to the first main scan condition that is frequently performed among the main scan conditions stored in the storage device 33. Specifically, the history of a plurality of main scan conditions stored in the storage device 33 is analyzed, and for example, main scan conditions that are frequently executed within a predetermined period in the past, such as the past two months, are extracted from the top. Then, the calibration scan condition is set so as to correspond to the extracted main scan condition group. In addition, when the main scan condition setting unit 52 sets a second main scan condition different from the first main scan condition, the calibration scan condition setting unit 54 performs calibration so as to correspond to the second main scan condition. Set the scan condition again.

  The calibration unit 55 calibrates the projection data of the subject 6 obtained in the main scan based on the calibration data generated by the calibration data generation unit 53.

  The image generation unit 56 generates an image of the subject 6 based on the projection data calibrated by the calibration unit 55. For example, the image generation unit 56 performs image reconstruction on projection data from a plurality of view directions by a filter-corrected back projection method, and generates image data of a tomographic image of the subject 6.

  The warning unit 57 sets the calibration scan condition again when the calibration scan condition set by the calibration scan condition setting unit 54 does not correspond to the main scan condition set by the main scan condition setting unit 52. To warn. For example, when the calibration scan condition setting unit 54 sets the calibration scan condition so as to correspond to the first main scan condition that is frequently executed among the main scan conditions stored in the storage device 33, the warning unit 57. Warns by displaying on the display device 32 that the calibration scan condition is to be changed based on the data in which the main scan condition setting means sets the second main scan condition different from the first main scan condition.

  The input device 31 of the operation console 3 is provided for inputting main scanning conditions such as a photographing method to the central processing unit 30, and is configured by, for example, a keyboard and a mouse.

  The display device 32 displays a tomographic image generated by reconstruction and various other information based on a command from the central processing unit 30.

  The storage device 33 stores various data, reconstructed images, programs, and the like, and the stored data is accessed by the central processing unit 30 as necessary. For example, the storage device 33 stores a history of the main scan conditions performed by the main scan control unit 42 for the main scan conditions set by the main scan condition setting unit 52, and stores the frequency of execution of the main scan conditions. The storage device 33 stores a history of main scan conditions within a predetermined period in the past, for example, for the past two months.

  Next, a method for setting calibration conditions using the X-ray CT apparatus 1 of the present embodiment will be described.

  FIG. 7 is a flowchart of a method for setting calibration conditions in the present embodiment.

  As shown in FIG. 7, first, the execution history of the main scan condition is acquired (S11).

  When taking a tomographic image of the subject 6, the operator inputs each setting item of the main scan condition to the input device 31 and outputs it to the central processing unit 30. Specifically, as the main scanning conditions, the slice thickness, the number of slices, and other imaging methods such as conventional scanning and helical scanning are input to the input device 31 by the operator, and the main scanning condition setting unit 52 of the central processing unit 30 is operated. A signal is output. Then, the main scan condition setting unit 52 outputs an operation signal to the main scan control unit 42, and the main scan control unit 42 outputs control signals CTL 30 a and CTL 30 b to the scanning gantry 2 and the imaging table 4. For example, the main scan control unit 42 outputs a control signal CTL 30 b to the imaging table 4 and causes the imaging table 4 to be carried into or out of the X-ray irradiation space 29 of the scanning gantry 2. Further, the main scan control unit 42 outputs a control signal CTL 304 to the rotation controller 28 to rotate the rotation unit 27 of the scanning gantry 2. Further, the main scan control unit 42 outputs a control signal CTL 301 to the X-ray controller 25 so that the X-ray tube 20 emits the X-ray 5. Then, the main scan control unit 42 outputs the control signal CTL 302 to the collimator controller 26 and controls the collimator 22 to shape the X-ray 5. Further, the main scan control unit 42 outputs a control signal CTL 303 to the data collection unit 24 and controls to collect projection data obtained by the detection element 23 a of the X-ray detector 23.

  At this time, the storage device 33 stores the history of the main scan conditions executed by the main scan control unit 42 for the main scan conditions set by the main scan condition setting unit 52, and stores the execution frequency of the main scan conditions. . The storage device 33 stores a history of main scan conditions within a predetermined period in the past, for example, for the past two months.

  Next, the execution frequency of the main scan condition is analyzed (S21).

  Here, the calibration scan condition setting unit 54 performs analysis based on the execution frequency of the main scan condition stored in the storage device 33. For example, the calibration scan condition setting unit 54 analyzes the history of a plurality of main scan conditions stored in the storage device 33, and sets the main scan conditions that are frequently executed within a predetermined past period such as the past two months. Extract from the top.

  Next, calibration scan conditions are set (S31).

  Here, the calibration scan condition setting unit 54 sets the calibration scan condition based on the history of the main scan condition stored in the storage device 33 and the analysis result of the execution frequency. For example, the calibration scan condition setting unit 54 sets the calibration scan condition so as to correspond to the main scan condition group extracted above. Specifically, when the apparatus can perform a main scan of tube voltages of 100 kV and 120 kV, and stores a history in which only 100 kV is performed in the main scan, it corresponds to 120 kV. First, a calibration scan condition corresponding to 100 kV is set.

  FIG. 8 is a flowchart showing analysis of the execution frequency of the main scan condition and setting of the calibration scan condition.

  As shown in FIG. 8, the execution history of the main scan condition is acquired (S101). Then, for example, it is determined whether or not a calibration scan corresponding to the main scan with the small focus is 100 V within the past N days (S111).

  If the tube voltage is 100V and the calibration scan corresponding to the main scan with the small focus is not performed within the past N days, the main scan is further performed Y times or less within the past X days. It is determined whether it has been done (S112). Then, if the main scan is not less than Y times within the past X days, it is set to perform a calibration scan corresponding to the main scan (S201).

  On the other hand, when the tube voltage is 100 V and the calibration scan corresponding to the main scan with the small focus is performed within the past N days, the calibration scan corresponding to the main scan condition is set to be omitted. (S301). Similarly, when the main scan is Y times or less within the past X days, the calibration scan corresponding to the main scan is set to be omitted (S301).

  Next, for example, it is determined whether or not a calibration scan corresponding to the main scan with the tube voltage of 120 V and the large focus has been performed within the past N days (S211, S311).

  If the tube voltage is 120V and the calibration scan corresponding to the main scan with the large focus has not been performed within the past N days, the main scan is further performed Y times or less within the past X days. It is determined whether it has been done (S212, S312). Then, if the main scan is not less than Y times within the past X days, a setting is made to perform a calibration scan corresponding to the main scan (S401, S501).

  On the other hand, when the tube voltage is 120 V and the calibration scan corresponding to the main scan with the large focus is performed within the past N days, the calibration scan corresponding to the main scan condition is set to be omitted. (S601, S701). Similarly, when the main scan is Y times or less within the past X days, the calibration scan corresponding to the main scan is set to be omitted (S601, S701).

  Then, when performing the calibration scan, the calibration scan control unit 43 causes the X-ray tube 20 to move the X-ray 5 through the air under the calibration scan condition set by the calibration scan condition setting unit 54. Scanning is performed by controlling each unit so that a reference setting object such as a phantom is irradiated and the X-ray detector 23 detects the X-ray 5 from the X-ray tube 20. The calibration scan is performed, for example, when the X-ray CT apparatus is started up about once a day.

  Then, based on the X-rays detected under the calibration scan condition, the calibration data generation unit 53 generates calibration data for calibrating characteristics such as detection sensitivity of the X-ray detector 23.

  When the calibration scan condition set by the calibration scan condition setting unit 54 does not correspond to the main scan condition set by the main scan condition setting unit 52, the calibration data generation unit 53 as described above. The calibration unit 55 calibrates the projection data of the subject 6 obtained in the main scan based on the calibration data generated in step S2. For example, the calibration scan condition setting unit 54 sets the calibration scan condition so as to correspond to the first main scan condition that is frequently executed among the main scan conditions stored in the storage device 33.

  Then, based on the projection data calibrated by the calibration unit 55, the image generation unit 56 performs image reconstruction by a filter-corrected back projection method, and generates tomographic image data of the subject 6.

  When the calibration scan condition set by the calibration scan condition setting unit 54 does not correspond to the main scan condition set by the main scan condition setting unit 52, the warning unit 57 again sets the calibration scan condition. Warning to set. For example, when the calibration scan condition setting unit 54 sets the calibration scan condition so as to correspond to the first main scan condition that is frequently executed among the main scan conditions stored in the storage device 33, the warning unit 57. Warns by displaying on the display device 32 that the calibration scan condition is to be changed based on the data in which the main scan condition setting means sets the second main scan condition different from the first main scan condition. Then, the calibration scan condition setting unit 54 sets the calibration scan condition again so as to correspond to the second main scan condition. Similarly, based on the calibration scan condition reset by the calibration scan condition setting unit 54, the calibration scan control unit 43 performs scanning, and based on the X-ray 5 detected under the calibration scan condition. Thus, the calibration data generation unit 53 generates calibration data.

  FIG. 9 shows a flowchart when a warning is executed by the warning unit 57.

  As shown in FIG. 9, the warning unit 57 obtains an instruction to execute a small focus main scan when the tube voltage is 100 kV (S801). Then, the warning unit 57 determines whether or not the calibration scan corresponding to the small focus main scan with the tube voltage of 100 kV has been performed within the past N days (S802).

  If the tube voltage is 100 V and the calibration scan corresponding to the main scan with the small focus is performed within the past N days, the execution of the main scan is permitted and the warning unit 57 does not warn (S901). ).

  On the other hand, if the tube voltage is 100 V and the calibration scan corresponding to the main scan with the small focus has not been performed within the past N days, the warning unit 57 issues a warning and corresponds to the main scan. The user is prompted to perform a calibration scan (S811). Then, it is determined whether or not a calibration scan corresponding to the main scan is performed. If the calibration scan is performed, the execution of the main scan is permitted, and the warning unit 57 does not warn (S901). If the calibration scan is not performed, the warning unit 57 again issues a warning and prompts execution of the calibration scan corresponding to the main scan (S811).

  As described above, according to the X-ray CT apparatus 1 of the present embodiment described above, the main scan condition setting unit 52 sets the main scan condition, and the storage device 33 is set by the main scan condition setting unit 52. The execution frequency for the main scan condition is stored. Then, the calibration scan condition setting unit 54 sets the calibration scan condition based on the execution frequency of the main scan condition stored in the storage device 33. Then, based on the calibration scan condition set by the calibration scan condition setting unit 54, the calibration scan control unit 43 performs the calibration scan. As described above, in the present embodiment, since the calibration scan condition is set so as to correspond to the execution frequency of the main scan condition stored in the storage device 33, the time required for calibration is reduced, and Usability can be improved and operability can be improved.

FIG. 1 is a block diagram showing an overall configuration of an X-ray CT apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a main part of the X-ray CT apparatus according to the embodiment of the present invention. FIG. 3 is a configuration diagram illustrating an X-ray detection module in the A column among eight X-ray detection modules constituting the X-ray detector in the X-ray CT apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing the interrelationship among the X-ray tube, the collimator, and the X-ray detector in the X-ray CT apparatus according to the embodiment of the present invention. FIG. 5 is a diagram illustrating the interrelationship among the X-ray tube, the collimator, and the X-ray detector in the X-ray CT apparatus according to the embodiment of the present invention. FIG. 6 is a configuration diagram showing the configuration of the central processing unit of the operation console in the X-ray CT apparatus according to the embodiment of the present invention. FIG. 7 is a flowchart of a method for setting calibration conditions in the X-ray CT apparatus according to the embodiment of the present invention. FIG. 8 is a flowchart showing the analysis of the execution frequency of the main scan condition and the setting of the calibration scan condition in the embodiment according to the present invention. FIG. 9 is a flowchart when a warning is executed by the warning unit in the embodiment according to the present invention.

Explanation of symbols

1 ... X-ray CT apparatus,
2 ... Scanning gantry,
3. Operation console,
4 ... Shooting table,
5 ... X-ray,
6 ... Subject,
20 ... X-ray tube,
21 ... X-ray tube moving part,
22 ... Collimator,
23 ... X-ray detector,
23a ... detecting element,
24 ... Data collection unit,
241 ... Selection / addition switching circuit,
242 ... Analog-to-digital converter,
25 ... X-ray controller,
26 ... Collimator controller,
27 ... rotating part,
28 ... Rotation controller,
29 ... X-ray irradiation space,
30 ... Central processing unit,
31 ... Input device,
32 ... display device,
33 ... Storage device,
41. Control unit,
42 ... this scan control unit,
43. Calibration scan control unit,
51: Data processing unit,
52 ... Main scan condition setting section,
53. Calibration data generation unit,
54 ... Calibration scan condition setting section,
55. Calibration section,
56 ... Image generation unit,
57 ... Warning section

Claims (2)

Based on the calibration scan condition, a calibration scan for irradiating the reference setting object with radiation is performed to generate calibration data for calibrating the characteristics of the detection means for detecting the radiation. Radiation irradiated and transmitted through the subject is detected by the detection means, the projection data of the subject is collected, the projection data is calibrated based on the calibration data, and based on the calibrated projection data A radiography apparatus for generating an image of the subject,
A main scan condition setting means for setting the main scan condition;
Storage means for storing an execution frequency for the main scan condition set by the main scan condition setting means;
Calibration scan setting means for setting the calibration scan condition based on the execution frequency of the main scan condition stored in the storage means;
A radiation imaging apparatus that performs the calibration scan based on the calibration scan condition set by the calibration scan condition setting means. If the calibration scan condition set by the calibration scan condition setting unit does not correspond to the main scan condition set by the main scan condition setting unit, a warning is issued to set the calibration scan condition again The radiation imaging apparatus according to claim 1, further comprising: a unit.

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