JPWO2014024857A1 - X-ray CT apparatus and imaging method of X-ray CT apparatus - Google Patents

Abstract

An X-ray CT apparatus according to the present invention includes a table that moves a subject in the body axis direction, an X-ray source that irradiates the subject with X-rays, and a rotating disk that holds the X-ray source and rotates based on a control command. (124), an X-ray detector that detects X-rays transmitted through the subject, an image processing unit that collects projection data based on the output of the X-ray detector and reconstructs an X-ray image, and a display device And an input / output device having an input device, and calculating a movement condition of the table that enables the collection of the projection data synchronized with the motion of the heart based on the inputted imaging condition, The movement condition is displayed as a chart having a body axis and a time axis, and the movement of the table (302) is controlled according to the movement condition of the table displayed on the chart.

Description

  The present invention relates to an X-ray CT (Computed Tomografhy) apparatus and an X-ray CT apparatus imaging method.

  In a commonly used X-ray CT apparatus, an X-ray source and an X-ray detector arranged to face the X-ray source rotate around the subject and irradiate the subject with X-rays from the X-ray source Then, X-rays transmitted through the subject are detected by an X-ray detector, and an image is reconstructed from the obtained projection data to create a tomographic image of the subject. In the reconstruction of the image, it is desirable that the subject and the organ in the subject are stationary. If the subject or its organ moves while acquiring projection data of the subject, the image is not correctly formed during image reconstruction, resulting in a blurred image, that is, a motion artifact.

  It is desirable to collect projection data by selecting a state with little movement in synchronization with the movement of the heart because the heart is constantly beating, especially when photographing the heart within the organ of the subject. . In cardiac imaging using an X-ray CT apparatus, for example, an electrocardiograph is attached to the subject, and the motion of the heart is reduced using the electrocardiogram information of the subject sent from the electrocardiograph. Select the phase and collect cardiac projection data. A method is used in which projection data is collected in synchronization with the movement of the heart and an image is reconstructed based on the projection data. This method is called an electrocardiogram synchronous reconstruction method.

  Thus, based on the electrocardiogram information of the subject sent from the electrocardiograph, the projection data of the heart in a relatively stationary state is obtained by collecting the projection data with a phase in which the heart motion is small. Motion artifacts in the reconstructed heart image can be reduced. An example of such an electrocardiographic synchronization reconstruction technique is described in Patent Document 1.

Japanese Unexamined Patent Publication No. 2011-50500

  For example, when photographing a moving organ such as a beating heart, it is desirable to collect X-ray projection data in synchronization with the movement of the organ. However, the conditions that enable the collection of X-ray projection data synchronized with the movement of the organ vary depending on the frequency of the movement of the organ, that is, the period. For this reason, the imaging conditions input to the X-ray CT apparatus by the operator are not always suitable for collecting projection data synchronized with the movement of the organ. The operator may have a hard time setting the X-ray CT apparatus's imaging conditions when imaging such moving organs. In some cases, an undesirable imaging condition is set. Motion artifacts may occur in the constructed image. When photographing a moving organ such as the heart, it is desirable to reduce the burden on the operator in photographing the X-ray CT apparatus.

  An object of the present invention is to provide an X-ray CT apparatus that can reduce the burden on an operator when imaging a moving organ such as a heart.

  The X-ray CT apparatus of the present invention is based on a table that moves the subject in the body axis direction, an X-ray source that irradiates the subject with X-rays, and a control command that holds the X-ray source. A rotating disk (124) that rotates, an X-ray detector that detects X-rays transmitted through the subject, and an image that collects projection data based on the output of the X-ray detector and reconstructs an X-ray image A processing unit; and an input / output device having a display device and an input device; and calculating a movement condition of the table that enables collection of the projection data synchronized with the motion of the heart based on the inputted imaging condition; The calculated movement conditions of the table are displayed as a chart having a body axis and a time axis, and the movement of the table (302) is controlled according to the movement conditions of the table displayed on the chart. .

  Furthermore, the imaging method of the present invention used for the X-ray CT apparatus includes an X-ray CT apparatus (100) including a table, an X-ray source, an X-ray detector, and an image processing unit (214) for reconstructing an X-ray image. An imaging method used for receiving the information on the heart motion of the subject and the imaging conditions, and collecting the projection data synchronized with the heart motion based on the received imaging conditions. The movement condition is calculated, the calculated movement condition of the table is displayed on a chart having a body axis and a time axis, and the movement of the table (302) is controlled by the movement condition of the table displayed on the chart. X-ray imaging.

  According to the X-ray CT apparatus or the imaging method of the X-ray CT apparatus according to the present invention, there is an effect that the burden on the operator can be reduced.

The block diagram of the X-ray CT apparatus which shows one Embodiment of this invention Block diagram showing the main configuration of the arithmetic and control unit Explanatory drawing explaining the function achieved by the operation of the arithmetic and control unit Flow chart showing outline of X-ray imaging procedure Explanatory drawing explaining the scanogram Explanatory drawing showing an example of ECG synchronous scan Screen of the monitor display device that displays the X-ray scan status and X-ray scan conditions Flow chart showing specific procedure for calculating electrocardiographic synchronization condition A flowchart showing a specific procedure for calculating an electrocardiogram synchronization condition when the fluctuation range of the heart rate is large Screen that displays the calculation results calculated according to the flowchart shown in FIG. Flow chart for calculating ECG synchronization conditions when the number of segments is changed Screen that displays the calculation results calculated according to the flowchart shown in FIG. Flowchart explaining a specific example of step S1210 described in FIG. Monitor display screen showing the progress of X-ray imaging Screen that displays whether or not to perform volume helical scan

  The embodiments described below are not limited to the contents described in the columns of “Means for Solving the Problems” and “Effects of the Invention” described above, but solve the various problems described below, There is an effect. The typical ones are listed below.

  In the following embodiments, the X-ray imaging area and the moving state of the table on which the subject is moved are displayed in relation to each other, so it is easy to determine whether X-ray imaging to be performed from now on is appropriate. Can be judged. In addition, it is possible to easily determine whether or not X-ray imaging is performed under the conditions of an ECG-gated scan, and it is possible to easily determine whether X-ray imaging to be performed is appropriate. Since the entire schedule of X-ray imaging can be viewed as an image based on the moving state of the table, it is easy to check the entire X-ray imaging, and whether the X-ray imaging to be performed in the future is appropriate or not Easy to judge.

  An already displayed X-ray imaging range and chart indicating the movement of the table can be used as an input screen, and new scanning conditions can be set, so that appropriate scanning conditions can be easily set. In addition, the X-ray imaging range can be displayed in comparison with the graph indicating the movement status of the table, and if one of these is changed, the other is also changed and the other is changed, making it easy to set appropriate scanning conditions. Can be set.

  The calculation unit calculates whether it is possible to take an ECG-synchronized scan under the input scan conditions, and displays a graph that allows ECG-synchronized scans, so that appropriate scan conditions can be set easily. . Or since the graph showing the area | region which can perform an ECG synchronous scan is displayed, an appropriate scanning condition can be set easily. When the input scan condition is changed, the diagnosis time and exposure dose are displayed accordingly, so that an appropriate scan condition can be easily set.

  Since a graph that enables ECG-synchronized scanning is displayed as a graph related to the moving speed of the table, the entire X-ray imaging can be easily grasped, and appropriate scanning conditions can be easily set.

  An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating a configuration of an X-ray CT apparatus 100 according to an embodiment. The X-ray CT apparatus 100 collects projection data of the subject 102 based on the X-ray irradiation to the subject 102, and an image such as a tomographic image or a three-dimensional image of the subject 102 based on the collected projection data Reconfigure.

  In addition, in the collection of projection data for moving organs represented by the heart, if necessary, information representing the movement of the organ, such as the subject's electrocardiogram information, is received and synchronized with the movement of the subject. Collect projection data. By collecting projection data in synchronization with the movement of the organ in this way, motion artifacts can be reduced. A typical example of a moving organ is the heart. When the heart is X-rayed, the electrocardiogram waveform of the subject 102 is measured by the electrocardiograph 106 as necessary, and the measured electrocardiogram waveform is the X-ray CT device. Projection data is received in synchronization with the movement received by the arithmetic control device 200 of 100 and synchronized with the motion of the subject 102.

  The X-ray CT apparatus 100 includes a table 302 on which the gantry 120, the arithmetic control device 200, and the subject 102 are placed. The gantry 120 includes a rotary disk 124 on which the X-ray source 126 and the X-ray detector 128 are mounted, an X-ray control device 142 that controls the X-ray irradiation of the X-ray source 126, and the rotational position and rotational speed of the rotary disk 124. Data collection for capturing a large amount of data detected by the X-ray detector 128, the bed control device 146 for controlling the movement and height of the table 302 on which the subject 102 is placed, and the gantry control device 144 to be controlled And a device (DAS: Data Acquisition System) 148. An opening 122 is formed at the center of the turntable 124, and the subject 102 moves along the body axis while being placed on the table 302 within the opening 122. Projection data is collected.

  When an operator inputs an imaging schedule and imaging conditions for performing X-ray imaging to the arithmetic and control unit 200, the X-ray source 126 is controlled by the X-ray controller 142 based on the input imaging schedule and imaging conditions. X-rays are emitted from the X-ray source 126. A high voltage generator (not shown) is provided on the turntable 124, and an X-ray tube and a collimator are provided in the X-ray source 126. The high voltage generator is controlled by the X-ray controller 142. A high voltage is supplied to the X-ray tube, and the X-ray tube generates X-rays based on the supplied high voltage. The X-ray generated by the X-ray tube is irradiated from the collimator onto the subject 102 placed on the table 302 at a predetermined irradiation angle. The irradiation angle in the rotation direction of the gantry among the irradiation angles is shown as a fan angle α.

  X-rays emitted from a collimator provided in the X-ray source 126 pass through the subject 102, and X-rays that have passed through the subject 102 enter the X-ray detector 128. The incident X-ray is detected by the X-ray detector 128 and converted into an electric signal corresponding to the intensity of the X-ray, whereby X-ray transmission image data is obtained. A data collection device (DAS) 148 collects transmission image data, converts it into a digital signal state, and supplies it to the arithmetic and control unit 200. The arithmetic and control unit 200 obtains projection data from the collected X-ray transmission image data, reconstructs a tomographic image or a three-dimensional image of the subject 102 based on the obtained projection data, and displays and stores it as image data. Save to. Furthermore, the projection data and image data can be transmitted to an external database and stored.

  When photographing a beating heart, the projection data is repeatedly collected at the timing at which the shape of the beating heart becomes substantially the same shape by photographing in the same phase in synchronization with the electrocardiogram waveform. be able to. By controlling the rotational speed of the turntable 124 with the gantry control device 144, the subject 102 is repeatedly photographed at different photographing angles by shifting the subject 102 at the same phase of the electrocardiogram waveform by a predetermined rotational angle based on the number of segments. It becomes possible. Projection data of each segment imaged at different imaging angles is obtained by the arithmetic control device 200 based on the X-ray transmission image data sent from the data acquisition device (DAS) 148 to the arithmetic control device 200, and the arithmetic control device 200 Reconstructs a cross-sectional image or a three-dimensional image based on the projection data of each segment.

  In this way, the arithmetic and control unit 200 collects segment-by-segment imaging data captured for each heartbeat, and uses a method of reconstructing an image using projection data of a plurality of segments, thereby obtaining an imaging angle at one heartbeat. This makes it possible to reduce the size and improve the time resolution in X-ray imaging. When the imaging target is a moving organ, the image quality can be improved by improving the time resolution.

  It is also possible to collect all projection data of the required rotation angle with one heartbeat without dividing into segments. In this case, the time resolution is reduced as compared with the segment dividing method. The number of segments is 1, that is, whether to perform X-ray imaging without dividing into segments, or to divide into multiple segments and perform X-ray imaging, and how many segments to use. The person decides.

  The present embodiment can be applied to various methods such as not dividing into segments or dividing into segments. When the projection data of the subject 102 is collected by dividing into the plurality of segments described above, the imaging conditions that enable the collection of projection data in each segment in synchronization with the movement of the heart, that is, the scanning conditions are not divided into segments. Setting is difficult compared to. Therefore, a greater effect can be obtained by applying the present invention in the case of shooting by dividing into segments than in the case of not dividing into segments. Note that a method of acquiring projection data in synchronization with the heart motion and reconstructing an image from the projection data in synchronization with the heart motion is referred to as an electrocardiographic synchronization reconstruction method in this specification.

  In the embodiment shown in FIG. 1, the X-ray source 126 and the X-ray detector 128 provided on the turntable 124 are disposed so as to face each other with the subject 102 interposed therebetween, and the turntable 124 is rotated to detect the subject. The projection data of the person 102 is collected. In this case, the time resolution can be improved by using a method of collecting projection data for each segment. In particular, when photographing an organ that moves like a heart, it is desirable to increase the time resolution. A method for collecting projection data by dividing into segments will be described below as an example.

  In FIG. 1, as an example, the X-ray detector 128 is provided at a position facing the X-ray source 126, and the X-ray source 126 and the X-ray detector 128 are moved around the subject 102 by the rotation of the rotating plate 124. It shows a rotating method. In this method, the X-ray detector 128 rotates, but other than this method, for example, a large number of X-ray detectors 128 are arranged around the subject 102 and only the X-ray source 126 rotates. The present invention is applicable.

  Although the X-ray CT apparatus 100 shown in FIG. 1 has been described above, an opening 122 is further provided at the center of the rotating disk 124, and the subject 102 is used to collect projection data in the body axis direction of the subject 102. The mounted table 302 moves. The position and moving speed of the subject 102 are controlled by the bed control device 146. By means of the gantry control device 144, the rotation speed of the rotating disk 124 including the X-ray source 126 and the X-ray detector 128 is rotated at a constant speed, for example, and the subject 102 placed on the table 302 of the bed 300 is By moving the table, the body moves in the direction of the body axis, whereby a helical scan can be performed. Shooting may be started after the rotation speed of the turntable 124 or the moving speed of the table reaches a constant speed, but shooting may be started before the speed reaches a constant speed in order to shorten the shooting time.

  The arithmetic and control unit 200 includes a CT control unit 212, controls the gantry control unit 144 and the bed control unit 146 and controls the X-ray control unit 142 based on the X-ray imaging schedule described later, and performs the above-described helical scan. X-ray transmission image data obtained by the data collection device (DAS) 148 is collected. When divided into segments, X-ray transmission image data is collected for each segment.

  The arithmetic and control unit 200 obtains photographing data through arithmetic processing by the image processing unit 214 and the reconstruction calculation unit 218 based on the transmission data of the segment unit collected by the data collecting device (DAS) 148. A tomographic image or a three-dimensional image is reconstructed based on the photographing data further obtained by the image processing unit 214 and the reconstruction calculation unit 218. These projection data calculation processing and calculation processing for reconstruction are performed with a very large amount of data to be processed, to reconstruct the image in the shortest possible time, or to reduce the processing amount of the image processing unit 214. In order to reduce this, a reconstruction calculation unit 218 is provided for dedicated calculation processing for correcting transmission image data and performing image reconstruction. The image data created by the reconstruction is sent to the image processing unit 214 and stored in the data recording device 226 (see FIG. 2). If necessary, it is stored in an external database 268 (see FIG. 2) provided outside via a network or the like in order to hold and manage data comprehensively in a hospital or the like.

  FIG. 2 is a block diagram showing the main configuration of the arithmetic and control unit 200. FIG. 3 shows various functions achieved by the operation of the arithmetic and control unit 200 shown in FIG. 2 and functions closely related to the present invention. The configuration of each functional block is achieved by the central processing unit 222 executing a processing program stored in the main memory 224.

  The arithmetic and control unit 200 is provided on the console of the X-ray CT apparatus 100. As shown in FIG. 1, as a main configuration, a CT control unit that comprehensively controls the X-ray CT apparatus 100 based on instructions from the operator. 212 and an image processing unit 214 and a reconstruction calculation unit 218 that perform projection processing on the projection data based on the transmission image data collected in the gantry 120 and reconstruct the image data from the projection data. The processing of the CT control unit 212, the image processing unit 214, and the reconstruction calculation unit 218 includes a central processing unit (CPU) 222 and a main memory 224 in which a control program for operating the central processing unit 222 is stored. Is done. The projection data collected by the processing of the central processing unit 222 and the reconstructed image data are stored and saved in the data recording device 226.

  The arithmetic and control unit 200 further includes an input / output processing unit 242 having a display memory 244, a network adapter 262 for connecting to a network 264 such as a local area network, a telephone line, and the Internet, and a bus line for connecting the above components. Has 250. The bus line 250 is further connected to the gantry 120 described with reference to FIG. 1 and controls the X-ray irradiation and the rotation angle and rotation speed of the rotating disk 124 via the X-ray control device 142 and the gantry control device 144. A large amount of data is collected from the data collection device (DAS) 148. The bus line 250 is connected to the bed 300 via the gantry 120, and a table on which the subject 102 is placed by controlling the lift unit 304 of the bed 300 by the bed control device 146 provided in the gantry 120. The height of 302 is adjusted and the movement of the table 302 in the body axis direction is controlled.

  Connected to the input / output processing device 242 are a monitor display device 246, a mouse 254 for inputting various operations and data, and an external input device 252. The external input device 252 is provided with a pointing device such as a touch panel, keys and switches for setting various parameters, a keyboard, and the like. The image data input to the display memory 244 included in the input / output processing device 242 is displayed on the monitor display device 246 as an image.

  Further, the monitor display device 246 includes a pointing device such as a touch panel, and by touching the display screen with a hand, it is possible to select a specific part in the display content, specify a position, and the like. Further, the selection content can be input by touching the selection request by the display of the monitor display device 246 by hand. Further, a printer (not shown) is connected to the input / output processing device 242, and an image or other display data displayed on the monitor display device 246 is displayed as an instruction from the external input device 252 or a display screen of the monitor display device 246. It is possible to print by a command from the touch panel.

  The data recording device 226 is a storage device such as a magnetic disk, and holds a large amount of projection data collected by the image processing unit 214 via the data collection device (DAS) 148. In order to collect the large amount of projection data, for example, the table 302 of the bed 300 on which the subject 102 is placed is moved at a constant speed in the body axis direction by the bed controller 146, and the X-ray source is moved by the gantry controller 144. Helical scanning is performed by rotating a rotating disk 124 having 126 and X-ray detector 128 at a constant speed. In this helical scan, the X-ray source 126 and the X-ray detector 128 move along the spiral trajectory with respect to the subject 102, and a large amount of projection data stored in the data recording device 226 is imaged along the spiral trajectory. It is obtained by calculation processing from a large amount of transmission data. Projection data is collected based on data photographed along the spiral trajectory, and an image is reconstructed from these projection data.

  The reconstruction calculation unit 218 reads data used as segment data from the data stored in the data recording device 226, performs interpolation calculation and correction calculation, and obtains projection data by calculation processing. Further, the projection data for each segment is used to perform a back projection operation or the like to reconstruct the image. Since the amount of processing related to interpolation calculation, correction calculation, and back projection calculation is very large, these processes may be performed by the central processing unit 222, but the load on the central processing unit 222 is reduced or image reconstruction is performed. In order to shorten the processing time, this embodiment includes a reconstruction calculation unit 218 that performs dedicated calculation processing.

  FIG. 3 is an explanatory diagram for explaining a function closely related to the present invention among the functions achieved by the block diagram shown in FIG. 2 and a process for achieving the function. The scanogram photographing unit 412 is a function that collects projection data for reconstructing a scanogram image based on a command from the input / output processing device 242 or a command generated in the course of executing another function.

  For example, the X-ray control unit 438, the gantry control unit 442, and the bed movement control unit 444 operate by the operation of the scanogram imaging unit 412. Due to the operation of the gantry control unit 442, the turntable 124 equipped with the X-ray source 126 and the X-ray detector 128 is fixed and maintained at a specific rotation angle, and the table 302 of the bed 300 is moved in the body axis direction by the bed movement control unit 444. Moving. Scanogram imaging is performed by this operation. The projection data collected by the scanogram imaging unit 412 is reconstructed by the image reconstruction function 422 using the reconstruction calculation unit 218, thereby creating a scanogram image. The reconstructed scanogram image is input to the display memory 244 of the input / output processing device 242, and the scan display image is displayed on the monitor display device 246 by the operation of the display control unit 432.

  From the image data of the scanogram, the position and shape of the subject 102 and the positional relationship with the table 302 of each part of the subject 102 can be known. The imaging range of the subject 102 can be designated based on the scanogram image data. The movement of the table 302 of the bed 300 can be controlled based on the specified range, and X-ray imaging can be performed.

  The imaging schedule setting unit 414 inputs and sets the X-ray imaging schedule of the subject 102. Specific imaging conditions for X-ray imaging are set by an imaging condition setting unit 416. The shooting condition setting unit 416 sets shooting conditions based on the input specific shooting conditions. In this setting process, the synchronization condition calculation unit 418 calculates whether or not X-ray imaging synchronized with the heart motion is possible under the input imaging conditions.

  Further, based on the imaging conditions input by the operator, the synchronization condition calculation unit 418 calculates the movement speed in the body axis direction of the table 302 that enables imaging synchronized with the waveform diagram of the heart, and the result is The image is displayed on the monitor display device 246 by the processing operation of the display control unit 432. When a change in the shooting condition is instructed by the chart displayed on the monitor display device 246 based on the display operation of the display control unit 432, the set value of the shooting condition is changed by the shooting condition setting unit 416, and the changed new Shooting conditions are set. Also, based on the imaging conditions set by the imaging condition setting unit 416, time resolution, X-ray imaging time, table moving time, exposure dose, etc. are calculated, and these data are input to the display memory 244 of the input / output processing device 242. Then, it is displayed on the monitor display device 246 by the operation of the display control unit 432.

  The X-ray imaging unit 420 performs X-ray imaging based on the imaging conditions set by the imaging condition setting unit 416. Based on an instruction to start imaging by the operator, the X-ray imaging unit 420 operates the X-ray control unit 438 to transmit a control command to the X-ray control device 142 and irradiate X-rays from the X-ray source 126.

  The gantry control unit 442 and the bed movement control unit 444 are operated by the operation of the X-ray imaging unit 420 together with the operation of the X-ray control unit 438. As a result, a control command is sent to the gantry control device 144 and the bed control device 146, and the turntable 124 equipped with the X-ray source 126 and the X-ray detector 128 is rotated based on the command to place the subject 102. The table 302 to be moved moves in the body axis direction based on the command. A large amount of data detected by the X-ray detector 128 is fetched from the data acquisition device (DAS) 148 and stored in the data recording device 226 according to a command from the X-ray imaging unit 420.

  The image reconstruction unit 422 reads out necessary data from the data stored in the data recording device 226, calculates projection data by performing interpolation calculation and correction calculation, and further, based on the projection data subjected to interpolation calculation and correction calculation, For example, back projection is used to reconstruct a cross-sectional image or a three-dimensional image of the subject 102.

  FIG. 4 is a flowchart for explaining an outline of an X-ray imaging procedure for performing X-ray imaging with the X-ray CT apparatus 100. When the X-ray imaging procedure S1000 of the X-ray CT apparatus 100 is started, the scanogram 1102 (see FIG. 5) is imaged in step S1100. The method for photographing the scanogram 1102 is as described above, and is performed by the scanogram photographing unit 412 (see FIG. 3).

  FIG. 5 is a diagram showing a scanogram 1102, and the Z-axis indicates a movement axis when the table 302 of the bed 300 moves in the direction from the entrance of the opening 122 of the gantry 120 to the back of the subject 102. It can be considered an axis. The X axis represents the direction of rotation of the turntable 124 on which the X-ray source 126 and the X-ray detector 128 are mounted. By scanning the scanogram, the subject 102 placed on the table 302 of the bed 300 can be positioned, and the position and shape of each part of the subject 102 are clarified.

  The scanning method of the scanogram 1102 has been described above based on the operation of the scanogram imaging unit 412 (see FIG. 3) .For example, the rotation angle of the turntable 124 on which the X-ray source 126 and the X-ray detector 128 are mounted is fixed, and the bed 300 When X-ray imaging is performed while moving the table 302 in the Z-axis direction, an image of a scanogram 1102 is obtained.

  The scanogram 1102 is photographed, and the obtained scanogram 1102 is displayed on the monitor display device 246. An X-ray imaging schedule, that is, a scan schedule for X-ray imaging, is input using the displayed scanogram 1102 image. A scan schedule 1152 and a scan schedule 1154 indicated by squares in FIG. 5 are examples of a scan schedule for the subject 102 displayed on the scanogram 1102 image. Furthermore, the scan schedule 1152 and the scan schedule 1154 also display photographing conditions such as photographing positions and photographing ranges, that is, scanning conditions for X-ray photographing.

  As the scanning conditions, a photographing position, a photographing range, a photographing direction, and the number of scans are input, and the input conditions are displayed on an image of the scanogram 1102, for example. The shooting position, shooting range, shooting direction, and number of scans may be input by an operator. Alternatively, a plurality of sets of measurement widths and measurement ranges for height may be stored in advance as a scan protocol, and input by selecting a suitable one from the scan protocols. In this way, by using the scan protocol, input becomes easy and input errors can be reduced.

  Since the reconstruction method to which the present invention is applied can achieve a great effect by applying the present invention to the segment method, an electrocardiographic scan in which X-ray imaging of the heart is performed by the segment method will be described next. Note that the reconstruction method to which the present invention is applied is not limited to the segment method.

  FIG. 6 is an explanatory diagram showing an example of an electrocardiographic synchronization scan that collects X-ray projection data in a segment manner in synchronization with the electrocardiogram 1062 of the subject 102 measured by the electrocardiograph 106 (see FIG. 1). . The electrocardiogram 1062 is repeatedly received by the arithmetic and control unit 200. For the sake of simplicity, it is assumed that the pulse rate of the electrocardiogram 1062 is stable and the cardiac cycle CC is in a stable state. In the following description, the cardiac cycle is represented by CC (Cardiac Cycle). A normal electrocardiogram 1062 has a P wave, an R wave, and a T wave as shown in FIG. In addition, Q waves and S waves are provided, but reference numerals are omitted in FIG.

  Any of the above-mentioned P wave, R wave, T wave, Q wave, and S wave may be used for the electrocardiogram synchronous scan, but as shown in FIG. 6, the R wave has a rapid extension and a high peak value. Therefore, it is easy to use and maintain high control accuracy. FIG. 6 shows an example using R waves. The shape of the heart changes corresponding to the electrocardiogram 1062, and can be regarded as substantially the same shape at the same phase of the electrocardiogram 1062.

  A tomographic image or a three-dimensional image can be reconstructed by scanning the heart with a predetermined slice width and collecting projection data with a rotation angle of 360 degrees or (180 degrees + α) in each slice. “Α” is a fan angle, which is an angle in the rotation direction (X axis) of the X-rays emitted from the X-ray source 126 shown in FIG.

  You can select the number of segments. FIG. 6 shows a case where the number of segments is set to 3. The phase T12 is set so as to correspond to a portion where the heart shape is stable in each cardiac cycle CC, that is, a portion where the change is slow. In the cardiac cycle CC1, cardiac cycle CC2, and cardiac cycle CC3, projection data with a rotational angle of 360 degrees or (180 degrees + α) is collected for one slice by scanning. In FIG. 6, for example, a case where projection data having a rotation angle of (180 degrees + α) is collected will be described.

  At the phase T12 of the cardiac cycle CC1, X-ray transmission data DS12 based on the detection value of the X-ray detector 128 is taken into the image processing unit 214 (see FIG. 1) via the data acquisition device (DAS) 148. The projection data SEG12 can be obtained based on the X-ray transmission data DS12, and the projection data SEG12 covers an angle wider than (π + α) / 3 in the rotation angle as shown in FIG. Next, the X-ray transmission data DS14 at the same phase T12 in the cardiac cycle CC2 is captured by the image processing unit 214 via the data acquisition device (DAS) 148, and the projection data DS14 is calculated by calculation.

  The calculated projection data DS14 covers a predetermined rotation angle positioned next to the predetermined rotation angle of the SEG 12 in the rotation angle. Further, the X-ray transmission data DS16 is taken into the image processing unit 214 via the data acquisition device (DAS) 148 at the phase T12 of the cardiac cycle CC3. Projection data covering a predetermined angle indicated by SEG16 is obtained by calculation from the acquired X-ray transmission data DS16. The rotation angle covered by the calculated projection data SEG12, projection data SEG14, and projection data SEG16 is (π + fan angle α) or larger. By collecting the projection data SEG12, SEG14, and SEG16 for the entire imaging range for each predetermined slice width, a tomographic image or a three-dimensional image of the heart can be reconstructed.

  In this embodiment, the table 302 is moved along the body axis with the rotation of the rotating disk 124, and the imaged portion is helical with respect to the slice position to be imaged by the subject 102. Moving.

  If the moving speed of the table 302 is fast, the table 302 moves in the body axis direction (Z-axis direction) after capturing the X-ray transmission data DS12 and before capturing the X-ray transmission data DS14 and X-ray transmission data DS16. The subject to be imaged by the subject 102 is out of the X-ray irradiation range of the X-ray source 126. In this case, the X-ray transmission data DS14 or the X-ray transmission data DS16 cannot be captured.

  The X-ray irradiation range of the X-ray source 126 has a width in the body axis direction (Z-axis direction). However, if the subject to be imaged is removed from this width, it becomes difficult to collect projection data. In the following description, the X-ray irradiation range in the body axis direction (Z-axis direction) is referred to as a beam width. As described above, depending on the setting of the imaging conditions including the scanning conditions, it may be difficult to capture projection data synchronized with the electrocardiogram 1062. Further, when the moving speed of the table 302 is slowed, there are problems that the photographing time becomes long and the exposure dose increases.

  Next, step S1200 for setting shooting conditions including a shooting schedule or scanning conditions will be described with reference to FIGS. 4, 5, and 7. FIG. In step S1100, the captured scanogram 1102 is displayed on the monitor display device 246 as shown in FIGS. 5 and 7, and the operator uses the displayed image of the scanogram 1102 to set the shooting schedule and the shooting conditions. Set up. In step S1210, a scan schedule 1152 and a scan schedule 1154 as shown in FIG. 7 are input on the display image of the scanogram 1102. The input scan schedule is displayed on the scanogram 1102 display image. Further, the imaging order of the scan schedule 1152 and the scan schedule 1154 is input as the scan schedule. By this input, the outline of the entire shooting schedule is determined.

  Based on the input scan schedule, the shooting schedule table 1162 displays the values of the shooting range L1 of the scan schedule 1152 and the shooting range L2 of the scan schedule 1154. Information about the heart obtained from the electrocardiograph 106 may be used for setting the imaging conditions. A specific input method for setting the shooting conditions and a specific change method of the input conditions will be described in detail below. First, the basic operation will be described along the configuration of step S1200 in FIG.

  In step S1210, the scan condition is specifically input. As shown in FIG. 7, the scan schedule 1152 is an electrocardiogram-synchronized scan that performs a scan in synchronization with the motion of the heart. On the other hand, the scan schedule 1154 is a scan that does not require synchronization with the heart. All conditions of the scan schedule 1152 and the scan schedule 1154 may be input at a time, or the input of the scan schedule 1152 and the scan schedule 1154 may be divided and input to one scan schedule first. However, if only one is input and the other condition is not input, the process returns from step S1216 to step S1210 again, and the remaining conditions are input.

  For example, the input of the scan schedule 1152 will be described. In step S1210, imaging conditions including a scan condition for performing an electrocardiogram synchronous scan are input. This input may be newly input for each condition one by one. Further, previously used conditions stored in the data recording device 226 or the like or standard conditions prepared in advance may be read and used. By reading and using already stored conditions, it is possible to reflect the experience more appropriately. Input scan conditions include, for example, the number of segments, gantry rotation speed, beam pitch, table moving speed, time resolution, whether the reconstruction type is half reconstruction or segment reconstruction, and the phase value for the ECG The heart rate of the subject 102, the heart rate fluctuation range, and the like. The heart rate may be automatically set from the electrocardiograph 106. Further, if not all of these are input but a certain set value is input, the input value may be calculated from the following relational expression. For example, when the gantry rotation speed is input, the beam pitch may be calculated, or the scan time may be calculated from the moving speed of the table.

  In the case of the scan schedule 1154, since it does not include the heart, as described above, the electrocardiogram-gated scan is not performed, and X-ray imaging by normal scanning is performed. Since the photographing object is different, the specific scanning conditions are different, but the basic operation is the same.

  In step S1210, a scan condition is input. In this input, as shown in the shooting schedule table 1162 in FIG. 7, a synchronous scan or an asynchronous scan is input as a scan condition. In step S1211, it is determined whether the scan is a synchronous scan. When performing an ECG-synchronized scan as in the scan schedule 1152, it is determined by calculation whether or not the ECG-synchronized scan can be performed under the scan condition input in step S1212. This calculation is performed by the synchronization condition calculation unit 418 (see FIG. 3). When it is determined by the calculation of the synchronization condition calculation unit 418 that it is difficult to perform the electrocardiogram synchronous scan, a condition that enables the electrocardiogram synchronous scan is obtained by the calculation. The calculation of whether or not these ECG synchronous scans are possible will be described below.

  By calculating the synchronization condition calculation unit 418, for example, by changing, for example, delaying the moving speed of the table 302, a calculation result that enables an ECG-synchronized scan is obtained. The moving speed of the table 302 and the scanning conditions related thereto are temporarily stored. Icons 1166, 1167, and 1168 shown in FIG. 7 indicate that they are temporarily stored. For example, when various scan conditions are changed and it is examined whether or not an electrocardiogram-synchronized scan is possible, input conditions and calculation results are temporarily stored each time, and an icon 1167 and an icon 1168 are displayed. By selecting the displayed icon 1166, icon 1167, or icon 1168, it is possible to return to the past examination content. Further, the contents of the selected icon are displayed in FIG.

  In step S1214, further necessary calculations are performed, and input values and calculation results are displayed as shown in FIG. When the operator determines that X-ray imaging may be performed under the displayed conditions and gives an instruction to execute imaging, execution proceeds from step S1216 to step S1400, and X-ray imaging is executed. When the operator further inputs and changes the scan condition, the execution shifts from step S1216 to step S1210 by performing an input or change operation.

  FIG. 7 is an image of the monitor display device 246 showing the X-ray imaging state and imaging conditions. A scan schedule 1152 and a scan schedule 1154 are displayed in association with the scanogram 1102 described with reference to FIG. Whether or not the scan schedule 1152 or the scan schedule 1154 is X-ray imaging based on an electrocardiogram-gated scan is displayed in the imaging schedule table 1162 based on the input. A graph 1112 is a graph depicting the shooting position when shooting is performed according to the scan schedule 1152 and the scan schedule 1154 in correspondence with the body axis and the time axis. Changes in the shooting position when shooting is performed according to the scan schedule 1152 and the scan schedule 1154 correspond to the movement direction, movement amount, and movement speed of the table 302 in the body axis direction.

  A graph 1112 represents a state in which the photographing position moves according to the conditions input by the operator, and corresponds to the movement of the table 302 as described above. A graph 1114 is a scan condition for enabling an electrocardiogram synchronous scan. In the scan conditions shown in the graph 1112 input by the operator, it is calculated in step S1212 in FIG. 4 that an ECG-synchronized scan is impossible, and a scan condition that enables a new ECG-synchronized scan in step S1212 Is calculated, a graph 1114 corresponding to the scan condition enabling the ECG-synchronized scan is displayed.

  The period from time t1 to time t2 is the time required to scan the scan schedule 1152 according to the conditions shown in the graph 1112. Further, the period from the time t3 to the time t4 is a time necessary for scanning the scan schedule 1154. The period from time t1 to time t5 is the time taken to scan the scan schedule 1152 based on the conditions shown in the graph 1114 in which the electrocardiogram synchronous scan is possible. Further, the period from the time t6 to the time t7 is an X-ray imaging time required for imaging the scan schedule 1154 under the condition of the graph 1114. Since the scan schedule 1154 is X-rayed asynchronously, X-ray imaging is possible under the conditions input by the operator. For this reason, the moving speed of the table 302 between the time t3 and the time t4 is the same as the moving speed of the table 302 between the time t6 and the time t7. Between time t2 and time t3 and between time t5 and time t6 is the time used to switch from scan schedule 1152 to scan schedule 1154 in X-ray imaging in graphs 1112 and 1114, and the position of table 302 Is controlled in accordance with the shooting range.

  In step S1212, the synchronization condition calculation unit 418 calculates whether the imaging condition including the input scan condition is a condition that allows an electrocardiogram synchronous scan with respect to the heart motion of the subject 102. Next, the contents of calculation as to whether or not the conditions for enabling electrocardiogram synchronization scanning are possible will be described.

  Among the scanning conditions input in step S1210, for example, the time RT required for one rotation of the heart rate HR or cardiac cycle CC (Cardic Cycle) rotating plate 124 of the subject 102 (hereinafter referred to as gantry rotation time) Then, using the conditions of the imaging range L, a scan condition that enables ECG-synchronized scanning is calculated. As described in FIG. 6, the heart contracts and expands from the R wave of the electrocardiogram 1062 to the next R wave, and pumps blood. This relationship is called a cardiac cycle phenomenon. For example, when an R wave is used as a reference, a period from an R wave to the next R wave and a cardiac cycle CC are obtained. The cardiac cycle CC can be obtained by the following formula 1 (Equation 1) using the heart rate of the subject. The numerical value “60” is a constant and is a numerical value in consideration of units and the like.

  In order to realize a scan that can be synchronized with the heartbeat of the subject, at least the width of the X-ray beam that is irradiated by the X-ray source 126 and can be detected by the detector 128, while the table 302 moves, X-ray transmission data DS12 or DS14, DS16 must be acquired. When the acquisition of the electrocardiogram information and the start of scanning are not synchronized, it takes two times the cardiac cycle to acquire the X-ray transmission data DS12 or the X-ray transmission data DS14 and the X-ray transmission data DS16.

  Therefore, if the scanning condition is such that the table 302 can be moved in accordance with the beam width of the detector over a time period that is two times or more of the cardiac cycle CC obtained using the heart rate of the subject 102, X-ray transmission data can be collected in synchronization with the electric information, projection data can be obtained based on this X-ray transmission data, and an image can be constructed. Here, the beam width of the detector is the spread of the X-ray beam irradiated from the X-ray source 126 in the body axis direction.

  The condition for synchronization with the heartbeat of the subject is that the heart rate HR (Heart Rate) and gantry rotation time RT (Rotation Time) of the subject are fixed, and the beam width BW (Beam It is only necessary to satisfy the condition that the time taken to move the table by (Width) is at least twice the cardiac cycle. In other words, if the table 302 moves so as to irradiate the subject on the table with the beam width BW taking more than twice the time of the cardiac cycle, information on the heartbeat for one stroke must be obtained. X-ray transmission data can be collected synchronously. For example, for a subject 102 with a heart rate of 60 times per minute (60 bpm), the cardiac cycle CC is 1 second (1000 ms), and in this case, the beam width is 2 seconds or more to the subject on the table. If the table is moved so as to irradiate, the scanning condition can be synchronized with the heartbeat. An expression that satisfies such a condition is expressed as follows.

  The moving speed TS (Table Speed) (m / s) of the table 302 is obtained by dividing the “distance traveled while the turntable 124 makes one revolution” by “the time taken for the turntable 124 to make one revolution”. It can be represented by the moving speed of 302, and becomes the following formula.

  This is because the beam pitch (BP) × beam width (BW) represents “the distance traveled during one rotation of the turntable 124”, and RT (gantry rotation time) (s / rot) represents “the turntable 124 This is because it represents “the time required for one rotation”.

  The table moving speed TS can also be written by the following equation using the time required for scanning (scanning time) (S) and the imaging range L of the subject.

  Substituting (Equation 3) into (Equation 2) gives the following equation (Equation 5).

  By substituting (Equation 1) into (Equation 5), it is possible to obtain an electrocardiographic scan condition based on the heart rate HR instead of the cardiac cycle CC. This conditional expression is expressed by Expression 6 (Equation 6). Furthermore, it can be transformed into an expression representing the condition of the beam pitch BP (the right side of Equation 6).

  Further, from (Equation 6), it can be transformed into an equation representing the condition of the gantry rotation time (RT) (Equation 7).

  A procedure for calculating the electrocardiographic synchronization condition of the subject 102 will be specifically described based on the conditional expressions (Equation 6) and (Equation 7) described above. FIG. 8 is a flowchart showing an example of a specific procedure for calculating the electrocardiographic synchronization condition of the subject 102. In particular, FIG. 8 shows a specific example detailing step S1212 and step S1214 shown in FIG.

  In the flowchart shown in FIG. 4, when the target of condition setting is the scan schedule 1152, the scan schedule 1152 is imaged by the electrocardiogram synchronous scan method, and therefore execution proceeds from step S1211 to step S1212. If it is not necessary to synchronize with the movement of the heart when performing a scan as in the scan schedule 1154, the execution shifts from step S1211 to step S1214, and step S1212 is not executed. Execution of S1212 starts execution of step S1250 of the electrocardiographic synchronization condition calculation flowchart shown in FIG. 8, which is a flowchart detailing steps S1212 and S1214.

  In this flowchart, before starting, either the gantry rotation time RT or the beam pitch BP is fixed. For example, if the gantry rotation time RT is fixed, the gantry rotation time RT or gantry rotation speed condition in the scan condition table 1164 shown in FIG. 7 is displayed as fixed. On the other hand, the beam pitch BP is displayed as variable. Correspondingly, the display of the scan condition table 1164 is also reversed. Assuming that the gantry rotation time RT or the gantry rotation speed is set to be fixed, the execution moves from step S1252 to step S1254.

  In step S1254, the condition of the beam pitch BP that enables the ECG-synchronized scan is calculated based on (Equation 6) from the heart rate HR of the subject 102 and the fixed gantry rotation time RT. The conditional expression of (Expression 6) is an inequality, and the value of the beam pitch BP that satisfies the condition is not uniquely determined, but here, not only the value BP0 of the beam pitch BP that satisfies the equal condition, but also the region that satisfies the inequality Is also required. For example, which region is the region that satisfies the inequality condition for the value BP0 of the beam pitch BP that satisfies the equal condition is obtained.

  In step S1255, the moving speed TS of the table 302 is calculated from (Expression 3) using the beam pitch BP satisfying the conditional expression (Expression 6) and the fixed gantry rotation time RT.

  When the equal condition of the conditional expression (Expression 6) is satisfied, as described above, the beam pitch BP is a unique value BP0, and the moving speed TS of the table 302 is also a unique value TS0.

  On the other hand, the beam pitch BP that satisfies the inequality condition represents a region with respect to the value BP0 of the beam pitch BP that satisfies the equal condition, and the moving speed TS of the table 302 is also changed to the moving speed TS0 that satisfies the equal sign (equal) condition. On the other hand, it represents a region. For example, considering not only the equal condition but also the area that satisfies the inequality condition, the moving speed TS of the table 302 is a speed equal to or lower than the moving speed TS0.

  Next, the scan time S is calculated in step S1256 from the imaging range L and the calculated table moving speed TS using (Equation 4). In addition to the scan time S0 based on the equal condition, considering the region that satisfies not only the equal condition but also the inequality condition, the scan time S in FIG. 7 is displayed in FIG. Is displayed in the photographing schedule table 1162 as the scan time S0 or more. A graph 1114 in FIG. 7 is a graph displayed based on the equal sign of the equality and inequality conditions of the expression (Equation 6), and the area based on the inequality condition has a slower table moving speed TS than the graph 1114. It becomes area A. The operator may select the value of the graph 1114 itself as the X-ray imaging conditions, but considering the fluctuation of the heart rate during the X-ray imaging of the subject 102, the region where the table moving speed TS is slower than the graph 1114 A specific value in A can be selected and set. If the specific value of the region A where the table moving speed TS is slower than the graph 1114 is used as a condition, the time t2 of the graph 1112 is moved along the time axis on the screen to obtain a new condition, for example, the new table moving speed TS. Is entered.

  Alternatively, the scan condition is changed by moving the slope of the graph, for example, by moving the point P1 of the graph 1112 to the point P2 of the graph 1114, and a new condition is input. With this new condition as a set value, a related numerical value is calculated, and the condition displayed in the scan condition table 1164 is changed to the calculated value. The operator can determine the final scan condition by looking at the calculation result.

  The calculated result is stored in the temporary storage memory in step S1257, and then in step S1258, the display based on the calculation result is performed as shown in the image of FIG. 7, and the new condition is displayed as described above. . Further, by storing in the temporary storage memory in step S1257, an icon indicating the presence of temporary storage is displayed as shown by an icon 1166, an icon 1167, and an icon 1168 in FIG. These icons indicate temporary storage of calculation results and are used to read out the stored calculation results.

  By selecting the display, the calculation result stored in the temporary storage memory is read out and displayed as shown in FIG. If there are multiple saves to the temporary storage memory, a plurality of corresponding icons are displayed, and one of the displayed icons is selected to display based on the calculation result corresponding to the selected icon This is performed on the monitor display device 246 in step S1258.

  Step S1258 is executed not only following step S1257 but also when an icon is selected, based on the selection of the icon. After step S1258, the calculation of the electrocardiographic synchronization condition and the display of the calculation result are ended in step S1259.

  FIG. 8 is a specific example of step S1212 and step S1214 shown in FIG. 4.After the end of the flowchart shown in FIG. 8, when step S1216 is executed and the operator selects X-ray imaging, FIG. In step S1400, X-ray imaging is performed.

  The above description of FIG. 8 is a case where the gantry rotation time RT is fixed and the beam pitch BP is variable as illustrated in FIG. Conversely, the case where the beam pitch BP is fixed and the gantry rotation time RT is variable will be described below. When the beam pitch BP is fixed, the execution proceeds from step S1252 to step S1262, and the condition of the gantry rotation time RT that enables the ECG-synchronized scan based on the heart rate HR of the subject 102 and the beam pitch BP Is obtained by calculation. Since the conditional expression (Equation 7) has an inequality sign, the value of the gantry rotation time RT that satisfies the conditional expression (Equation 7) is not uniquely determined. A value RT0 of the gantry rotation time RT that satisfies the equality condition of the conditional expression (Equation 7) is calculated, and further, an area following the gantry rotation time RT0 is calculated in consideration of the inequality.

  Based on the calculation result of step S1262, in step S1264, the table moving speed TS is calculated from (Equation 3) using the gantry rotation time RT and the fixed beam pitch BP. Further, as described above, in step S1256, the scan time S is calculated from the imaging range L and the table moving speed TS calculated using (Equation 4).

  This calculation is the same as the calculation when the gantry rotation time RT is fixed. In step S1257, the calculated data is saved and displayed in step S1258 as a chart on the operation screen as shown in FIG. As described above, since the table moving speed TS in the ECG synchronous scan is calculated not only by the condition indicated by the equal sign but also by the condition indicated by the inequality sign, the graph 1114 in FIG. Represents an inequality condition.

  Since either the gantry rotation time RT or the beam pitch BP described above is fixed and the calculated table moving speed TS and scan time S are different, the graph 1114 is a chart on the operation screen as a different graph as a synchronization condition. Is displayed.

  However, in (Equation 6) or (Equation 7), if the beam pitch BP or the gantry rotation time RT is only a value that satisfies the equality of the conditional expression, the beam pitch BP can be calculated even when the gantry rotation time RT is fixed. Even when the calculation is performed in a fixed manner, the table moving speed TS and the scan time S show the same value. This is because if the equation satisfying the equality of (Equation 6) or (Equation 7) is substituted into (Equation 3), the moving speed TS of the table is expressed by the following equation, regardless of which is fixed.

  When the chart movement speed TS and scan time S are also displayed on the operation screen at the same time, the maximum value of the table movement speed TS and the minimum value of the scan time S can be visually understood. It is effective because it can. In FIG. 7, the time between time t1 and time t2 is the scan time S1 at the setting value set by the operator that makes it difficult to perform an ECG-synchronized scan, and the time between time t1 and time t5 is the calculation result Is a scan time S2 at a set value at which an electrocardiogram synchronous scan can be executed.

  Furthermore, when it is necessary to consider the heart rate variability of the subject 102, the operator considers the heart rate variability and inputs the heart rate variability range as described above. The gantry rotation time RT in consideration of the fluctuation range of the heart rate can be obtained from the scanning conditions under which the electrocardiogram-synchronized scanning is possible, and the moving speed TS of the table 302 can be obtained. Furthermore, using the minimum heart rate and the maximum heart rate within the input heart rate HR fluctuation range, in addition to the scanning conditions that can be synchronized with ECG using the above means, the scan time at that time corresponds to the heart rate fluctuation range. Can be calculated.

  FIG. 9 is a flowchart for calculating the electrocardiographic synchronization condition of the subject 102 with a large heart rate fluctuation range. The basic concept is the same as that of the flowchart shown in FIG. 8, and steps having the same reference numerals indicate processes having the same contents and have the same operational effects. First, similarly to the flowchart described in FIG. 8, either the gantry rotation time (RT) or the beam pitch (BP) is set to a fixed state.

  When the gantry rotation time RT is set to the fixed state, the process proceeds from the execution of step S1252 to the execution of step S1272. In step S1272, the maximum value HRH and the minimum value HRL of the heart rate HR of the subject 102 are input in advance. Further, in step S1272, the conditions of the beam pitch BP that enables the ECG-synchronized scan based on the maximum value HRH and minimum value HRL of the input heart rate HR and the fixed gantry rotation time RT based on (Equation 6) are set. Obtained by calculation (S1272). At this time, there are two conditions, the beam pitch BP condition at the maximum value of the heart rate HR and the beam pitch BP condition at the minimum value of the heart rate HR. Ask.

  Since this conditional expression is an inequality, the value of the beam pitch BP that satisfies this expression is not uniquely determined. Not only the equality of the conditional expression but also the value satisfying the inequality sign is calculated. As described above, the beam pitch BP that satisfies the conditional expression (Equation 6) is calculated in step S1272. Next, in step S1255, the moving speed TS of the table 302 is calculated from (Equation 3) using the beam pitch BP obtained by the above calculation and the fixed gantry rotation time RT.

  In the same manner as described above with reference to FIG. 8, in step S1256 of FIG. 9, the scan time S is calculated from the imaging range L and the calculated table moving speed TS using Equation (Equation 4). Next, in step S1257, the calculated data is temporarily stored, and in step S1258, setting conditions and calculation results are displayed. The display contents are shown in FIG.

  Next, instead of the gantry rotation time RT, when the beam pitch BP is fixed, the execution moves from step S1252 to step S1273, and in step S1273, the maximum value and minimum value HRL of the heart rate HRH of the subject 102, Based on (Equation 7) from the beam pitch BP, the condition of the gantry rotation time RT at which the ECG synchronous scan is possible can be obtained by calculation.

  At this time, similarly to the calculation with the gantry rotation time RT fixed, the condition of the gantry rotation time RT at the maximum value HRH of the heart rate HR and the condition of the gantry rotation time RT at the minimum value HRL of the heart rate HR are calculated. There are two conditions, and two values of the gantry rotation time RT that satisfy each condition are obtained. Since the conditional expression has an inequality condition in addition to the equal sign, the value of the gantry rotation time RT that satisfies the conditional expression is not uniquely determined.

  Here, if there are only equal conditions in the conditional expression, the value of the gantry rotation time RT can be specified, and an area having the specified gantry rotation time RT as a boundary can be obtained according to the condition of the inequality sign of the conditional expression. Can do. The boundary value and region of the table moving speed TS are obtained by calculation from step S1264 using (Formula 3) using the boundary and region of the gantry rotation time RT satisfying this conditional expression and the fixed beam pitch BP.

  In step S1256, similarly to the above-described processing, the scan time S is obtained by calculation from the imaging range L and the calculated table moving speed TS using (Equation 4). Then, in the same manner as when calculating with the gantry rotation time RT fixed, the calculated data is stored in the temporary storage memory in step S1257, displayed in the chart on the operation screen in step S1258, and in step S1279. The process ends, and execution proceeds to step S1216 in FIG.

  A chart on the operation screen displayed in step S1258 is shown in FIG.

  Since either the gantry rotation time RT or the beam pitch BP described above is fixed and the calculated table movement speed TS and scan time S are different, the two types of graphs are totaled as two synchronization conditions. Four graphs will be displayed on the chart on the operation screen. However, in FIG. 10, since the display becomes complicated, one of the graphs drawn separately is omitted and displayed when the gantry rotation time RT is fixed and when the beam pitch BP is fixed.

  As described above, in (Equation 6) or (Equation 7), when the beam pitch BP or the gantry rotation time RT takes a value satisfying the equality of the conditional expression, the calculation is performed with the gantry rotation time RT fixed. The table moving speed TS is equal to the scan time S when the calculation is performed with the beam pitch BP fixed (Formula 8). Furthermore, although different values are taken into consideration when considering specific individual conditions, the same result is obtained when operations are performed on basic parameters. In this case, it can be dealt with by calculation under one condition.

  In addition to the calculation result chart as described above, when the table moving speed TS and scan time are simultaneously displayed on the chart on the operation screen, the maximum value of the table moving speed TS and the minimum value of the scan time can be visually observed. It is effective because it can be seen and understood. It is also useful for managing exposure dose.

  The basic concept of the chart on the operation screen described in FIG. 10 is substantially the same as FIG. FIG. 7 shows an example in which a scan schedule 1152 and a scan schedule 1154 are set, but in FIG. 10 only the scan schedule 1152 is set and the scan schedule 1154 is not set for the sake of simplicity. As described based on FIG. 8, also in FIG. 10, in step S1258, an icon 1166, an icon 1167, or an icon 1168 indicating a history is displayed every time temporary storage is performed.

  In step S1272, when the maximum heart rate HRH (for example, heart rate 70 bpm) and the minimum heart rate HRL (for example, heart rate 62 bpm) are input, the graph 1115 and the graph 1117 of the table moving speed TS based on each are calculated and displayed. Is done. A graph 1115 specified by the points P1 and P3 is a condition corresponding to the equal sign of the arithmetic expression (Equation 6) among the conditions enabling the electrocardiogram synchronous scan corresponding to the maximum heart rate HRH. Further, the region where the table moving speed TS is slower than the graph 1115 is a condition that satisfies the inequality sign of the arithmetic expression (Equation 6). The graph 1115 is the condition that the table moving speed TS is the fastest among the conditions that enable the ECG-synchronized scan corresponding to the maximum heart rate HRH, and has an advantage that the scan time is shortened.

  On the other hand, the graph 1117 specified by the point P1 and the point P4 is a condition corresponding to the equal sign of the arithmetic expression (Expression 6) among the conditions that enable the ECG synchronous scan corresponding to the minimum heart rate HRL. .

  A region where the table moving speed TS is slower than the graph 1115 is a condition that satisfies the inequality sign of the arithmetic expression (Equation 6). A graph 1117 is a condition in which the table moving speed TS is the fastest among the conditions that enable the ECG-synchronized scan corresponding to the minimum heart rate HRL. There is an advantage that the scanning time is shortened.

  The operator determines from the fluctuation state of the heart rate HR of the subject 102, and further considers the graph 1115 corresponding to the maximum heart rate HRH and the graph 1117 corresponding to the minimum heart rate HRL from the chart of FIG. Scan conditions can be set. For example, when the point P2 is selected on the chart, the heart rate HR corresponding to the point P2 is detected and set. Alternatively, when a heart rate HR value is input to the scan condition table 1164, the scan condition can be set and a graph representing the table moving speed TS on the chart corresponding to the selected heart rate HR value, for example, a graph 1116 is displayed.

  The above embodiment shows the conditions for collecting data in synchronism with the electrocardiogram information and making it possible to reconstruct an X-ray image. In other words, it is a condition for reconstructing an image with one segment. In the imaging method (herein referred to as retrospective scan) in which a helical scan is performed while capturing electrocardiogram information and then image reconstruction is performed in synchronization with the electrocardiogram information (herein referred to as retrospective scan), multiple heartbeats are created in order to create an image with higher temporal resolution. There is a method of reconstructing an image by collecting projection data having different projection angles. This is called a multi-segment reconstruction method, and projection data for one heart beat among a plurality of heart beats is referred to as a segment as shown in FIG. As the number of segments increases, an image with higher temporal resolution can be obtained.

  The ECG synchronization conditional expression shown in (Equation 2) is for the case where the number of segments is 1.Because information for one heartbeat can be obtained without fail, twice the time of the cardiac cycle CC is required. Therefore, the right side is twice the cardiac cycle CC. If the number of segments is 2, it takes 3 times longer than the cardiac cycle CC in order to be able to obtain information for 2 heartbeats, so the right side of (Equation 2) is the heart cycle CC. Tripled. Similarly, if the number of segments is 3, the right side of (Equation 2) is four times the cardiac cycle CC. That is, the right side of (Equation 2) uses one more cardiac cycle CC than the number of segments. This is expressed as follows.

  The number of heartbeat projection data DS to be used is determined by the number of segments input by the operator. Although the case where the number of segments is 1 to the case where the number of segments is 3 has been described above, a larger number of segments can be similarly considered. The flowchart in FIG. 11 is a processing procedure showing details of steps S1212 and S1214 in FIG. 4, and FIG. 12 shows a screen displayed on the monitor display device 246 based on the flowchart in FIG.

  In step S1210 of FIG. 4, the scan area shown in FIG. 12 is shown as a scan schedule 1152 on the scanogram 1102. Further, in step S1210 of FIG. 4, it is input that the scan schedule 1152 is an electrocardiogram-synchronized scan, and other scan conditions such as the number of segments are input by the operator. As shown in the imaging schedule table 1162 in FIG. 12, in accordance with the input by the operator at step S1210, electrocardiogram synchronous scan imaging is displayed as the imaging condition.

  Based on the input in step S1210, an electrocardiogram synchronous scan is determined in step S1211 of FIG. 4, and execution proceeds from step S1211 to step S1212. That is, execution of step S1280 shown in FIG. 11 is started. At the input of step S1210, the gantry rotation time RT is displayed as fixed in the scan condition table 1164 of FIG. 12. First, a case where the gantry rotation time RT is fixed will be described. Note that if the input at step S1210 inputs that the beam pitch BP is fixed and the gantry rotation time RT is variable, this is displayed in the scan condition table 1164 of FIG. In this example, as described above, a case where the gantry rotation time (RT) is first fixed will be described.

  When the gantry rotation time RT is set to the fixed state, the process proceeds from step S1252 to step S1282. In step S1282, the number of segments (SEG) and the heart rate (HR) input in step S1210 of FIG. 4 are used. Further, in step S1282, a beam that can be subjected to an ECG-synchronized scan based on (number 9) from the number of segments (SEG) and heart rate (HR) previously input in step S1210, and the fixed gantry rotation time RT (number 9) The condition of the pitch BP is obtained by calculation (S1282).

  Since the conditional expression of (Equation 9) is an inequality, as described above, the value of the beam pitch BP that satisfies this expression is not uniquely determined. Not only the equality of the conditional expression but also the value satisfying the inequality sign is calculated. In step S1282, a beam pitch BP that satisfies this conditional expression (Formula 9) is calculated. Next, in step S1255, the moving speed TS of the table 302 is calculated from (Equation 3) using the beam pitch BP obtained by the above calculation and the fixed gantry rotation time RT.

  In the same manner as described above based on FIG. 8, in step S1256 of FIG. 11, the scan time S is calculated from the imaging range L and the calculated table moving speed TS using the equation (Equation 4). Next, in step S1257, the calculated data is temporarily stored, and in step S1258, setting conditions and calculation results are displayed. The display contents are shown in FIG.

  In FIG. 12, the condition input by the operator in step S1210 shown in FIG. 4 is a graph 1120. For example, the number of segments is one. Under this scanning condition, the table moving speed TS is fast and the exposure dose is small. However, as shown in the imaging schedule table 1162 as “No”, this scan condition does not satisfy the condition of the electrocardiogram synchronous scan in the calculation according to the flowchart of FIG. Therefore, it cannot be used. A table moving speed TS at which the ECG synchronous scan obtained by the calculation described in FIG. 11 can be performed is a graph 1121. The graph 1121 is a boundary condition that satisfies the equal sign of the conditional expression. In the region where the table moving speed TS is slower than the graph 1121, the condition of the inequality sign of the conditional expression is satisfied, and an electrocardiogram synchronous scan can be performed. The above example is a graph in which the number of segments is 1.

  When the number of segments is 1, the time resolution is low, and the display 1171 shown in the scan condition table 1164 in FIG. 12 is selected. When display 1171 is selected, there is an advantage that high-speed shooting is performed, but a disadvantage is that image quality is lowered. To increase the image quality, display 1172 is selected. Increasing the number of segments can improve image quality.

  Step S1289 in FIG. 11 is connected to step S1216 in FIG. 4, and the process returns from step S1216 in FIG. 4 to step S1210 again, and can be increased by changing the number of segments. For example, in the graph 1121, the number of segments is 1, and when the number of segments is changed to 2, next, step S1280 of FIG. 11 is executed after step S1211. When execution proceeds from step S1252 to step S1282, the number of segments is changed to 2 and the operations of step S1282 and step S1255 are executed. In step S1256, the scan time when the number of segments is 2 and the table moving speed TS are calculated. Similar to the previous time, the calculation result is temporarily stored in step S1257, and additionally displayed in FIG. 12 in step S1258. In addition to the segment 1 graph 1120 and the graph 1121, a segment 2 graph 1122 is displayed.

  Similarly, when the number of segments is changed to 3, for example, the calculation in step S1282 and step S1255, and further the calculation in step S1256 are performed under the condition that the number of segments is changed to 3, and the number of segments is 3 in the chart of FIG. A graph 1123 is additionally displayed. Increasing the number of segments increases the shooting time but improves the time resolution, and selecting the display 1172 in the scan condition table 1164 in FIG. 12 has the advantage of improving the image quality. The operator can set imaging conditions suitable for the subject 102 with reference to the graph 1121, the graph 1122, and the graph 1123 in consideration of the imaging time and image quality related to the exposure dose.

  Note that the icon 1166 and the icon 1168 are displayed corresponding to the saving in step S1257, and the calculation result is reproduced by selecting the icon. Further, when the graph 1121, the graph 1122, and the graph 1123 are selected by an operation such as a click, detailed photographing conditions of the selected graph are displayed in the photographing schedule table 1162 and the scanning condition table 1164.

  Next, a case where the beam pitch BP is fixed instead of the gantry rotation time RT will be described. The execution shifts from step S1252 to step S1283, and in step S1283, the gantry rotation time at which an ECG-synchronized scan can be performed based on (number 9) from the number of segments SEG, the heart rate HR of the subject 102, and the beam pitch BP RT conditions are obtained by calculation. As described above, since there is an inequality condition in addition to the equality sign in the conditional expression, the value of the gantry rotation time RT that satisfies the conditional expression is not uniquely determined, and the boundary (solution of the equality) and region (the inequality Solution) is obtained by calculation. Using the gantry rotation time RT satisfying this conditional expression and the fixed beam pitch BP, the boundary value and region of the moving speed TS of the table are calculated by calculation in step S1264.

In step S1256, similarly to the above-described processing, the scan time S is obtained by calculation from the imaging range L using (Equation 4) and the calculated table moving speed TS. Then, in the same manner as when calculating with the gantry rotation time RT fixed, the calculated data is stored in the temporary storage memory in step S1257, displayed in the chart on the operation screen in step S1258, and in step S1289. Then, the process ends, and the execution moves to step S1216 in FIG.
A chart on the operation screen displayed in step S1258 is shown in FIG.

  Since either the above gantry rotation time RT or beam pitch BP is fixed and the calculated table moving speed TS and scan time S are different, two types of graphs are available for each segment as synchronization conditions. Will be displayed on the chart on the operation screen. However, in FIG. 12, since the display becomes complicated, one of the graphs drawn separately is omitted and displayed when the gantry rotation time RT is fixed and when the beam pitch BP is fixed.

  In (Equation 9), when the beam pitch BP or the gantry rotation time RT takes a value that satisfies the equality of the conditional expression, as in the case where the number of segments is 1, the calculation is performed with the gantry rotation time RT fixed. The table moving speed TS and the scanning time S are the same when the calculation is performed with the beam pitch BP fixed. The table moving speed at that time is expressed by the following Equation 10 (Equation 10).

  In addition to the calculation result chart as described above, when the table moving speed TS and scan time are simultaneously displayed on the chart on the operation screen, the maximum value of the table moving speed TS and the minimum value of the scan time can be visually observed. It is effective because it can be seen and understood. It is also useful for managing exposure dose.

  The basic concept of the chart on the operation screen shown in FIG. 12 is substantially the same as in FIGS. Similar to FIG. 10, in FIG. 12, only the scan schedule 1152 is set and the scan schedule 1154 is not set to simplify the description. In FIG. 12, in step S1258, an icon 1166, an icon 1167, or an icon 1168 indicating a history is displayed every time temporary storage is performed.

  In step S1282, when a certain number of segments is input, the boundary and area of the table moving speed TS based on the number are calculated and displayed. For example, when the number of segments 1 is input, the table moving speed TS based on it is calculated and a graph 1120 is displayed, when the number of segments is 2, a graph 1122 is displayed, and when the number of segments is 3, A graph 1123 is displayed. Those graphs are graphs that satisfy the conditions corresponding to the equal sign of the arithmetic expression (Equation 9) among the conditions that enable ECG synchronous scanning, and at this time, the table moving speed TS is the fastest. The area of the table moving speed TS that satisfies the inequality sign of the equation (Equation 9) is an area where the table moving speed TS is slower than the displayed graph.

  As can be seen from FIG. 12 and (Equation 10), the table movement speed (TS) decreases as the number of segments increases (the time resolution increases).

  The display screen of FIG. 12 graphically displays whether the high-speed shooting type or the high-quality type. If the operator wants to shorten the examination time in consideration of the heart rate HR of the subject 102, select the high-speed imaging type (small number of segments or low temporal resolution) condition and examine with an emphasis on image quality. If it is desired to perform the above, it is possible to easily perform the inspection required by the operator by selecting the condition of the high image quality type (the number of segments is large or the time resolution is high).

  Scan conditions can be set from the chart of FIG. For example, if the number of segments 2 (SEG2) is selected on the chart (displayed with a solid line), the corresponding table moving speed TS and scan time T are displayed, and the exposure dose is also displayed. In this way, the operator can select an appropriate number of segments (SEG). Similar to the above-described embodiment, the rotation of the X-ray source 126 and the turntable 124 shown in FIG. 1 is controlled according to the selected condition, and the bed 300 shown in FIG. 2 is controlled, and the table 302 is set according to the scan schedule. Movement is controlled.

  FIG. 13 is a flowchart for changing the set value using the displayed screen when the calculation result is already displayed as shown in FIG. 7, FIG. 10, FIG. Step S1210 in the flowchart shown in FIG. 4 has a function of inputting a completely new scan condition and a function of changing a scan condition that has already been input. A specific example for achieving the function of changing the already input scan condition among the functions of step S1210 shown in FIG. 4 will be described with reference to FIG.

  Now, assuming that the screen shown in FIG. 7 is displayed on the monitor display device 246, the flowchart of FIG. 13 will be described. When the operator changes the scan condition while viewing the screen shown in FIG. 7 displayed on the monitor display device 246, the operator first designates an object on the screen to be changed. For example, when the graph 1112 that is the scan condition is changed to the graph 1114 that is the scan condition, there are the following two methods. The first method is a method of moving the point P1 of the graph 1112 to the point P2 of the graph 1114. The second method is a method of directly specifying the graph 1114.

  In the first method, since the point P1 is continuously moved, not only the point P2 on the graph 1114 but also a point in the region A adjacent to the point P2 can be selected. Furthermore, by moving the target while dragging, the values in the chart, shooting schedule table 1162 and scan condition table 1164 are changed correspondingly during the movement, so see the chart, shooting schedule table 1162 and scan condition table 1164. However, there is an advantage that the set value can be determined. On the other hand, the second method has an advantage that the scan condition can be changed with a simple device to the change condition already planned.

  The flowcharts shown in FIG. 4, FIG. 8, FIG. 9, FIG. 11, and FIG. 13 are described in a series of easy-to-understand flows, but are actually divided into a plurality of programs, for example, very short time intervals. Will be executed repeatedly. The flowchart of FIG. 13 described below is actually repeatedly executed in a short cycle, so that the calculation is repeatedly performed in the middle of the drag operation, and the chart, the shooting schedule table 1162, and the scan condition table follow the drag operation. The display of 1164 changes. Therefore, there is an advantage that the scan condition can be set by dragging while watching the change in display.

  As described above, when the flowchart shown in FIG. 13 is repeatedly executed in a short cycle and step S1300 is executed, it is determined whether the change target is selected or has already been selected in step S1312. In step S1312, if the step condition change target is not selected, the flowchart from step S1300 ends once in step S1346, and step S1300 is executed again in the next execution cycle repeated in a short cycle. Is done.

  When the change target in FIG. 7 is designated in step S1312, the display of the selected change target is changed in step S1314 so that the operator can confirm the change target. For example, changing the display color or changing the type of pattern such as changing the solid line to a broken line is performed. Note that the selection of the change target in step S1312 is performed by, for example, a click operation.

  Next, in step S1314, it is determined whether the change target is a chart or scan schedule 1152, or a numerical value or a fixed or variable alternative part.

  If the change target is a chart or scan schedule 1152 or the like, execution proceeds to step S1318.

  Next, in step S1318 or in step S1342, it is determined whether there is a new operation for changing the scan condition. This change is performed by, for example, a drag operation. In step S1318, it is determined whether there is a change by the drag operation. For example, if the point P1 of the graph 1112 is selected as a change target and the point P1 of the graph 1112 is moved by dragging, the drag position of the point P1 at the time of executing step S1318 and the next step S1322 even during the dragging Is taken as a new input point in step S1322, and calculation and display are performed in step S1324 based on the position of the drag of the fetched point P1. By such an operation, the image in FIG. 7 is changed based on the drag operation using the value in the middle of the drag as an input value. It functions as the final input value at the end of the drag.

  If the scanning condition is changed by clicking instead of changing the scanning condition by dragging, the execution moves from step S1318 to step S1342, the click operation is detected in step S1342, and the scanning condition is read in step S1344 as the changed scanning condition. This becomes a new set value. Based on the new set value read in step S1344, the procedure from step S1211 to step S1214 in FIG. 4 is executed, and the newly input scan condition is displayed as shown in FIG. Since the flowchart starting from step S1300 is repeatedly executed in a short cycle, if the click for inputting the scan condition is repeated many times, a graph with the change of each click position as a new input value corresponds to each click. And change. In this case, the display is similar to the drag operation, and it is possible to select an appropriate scan condition from repeated drags.

  Even when the scan schedule 1152 instead of the graph 1112 is selected as the change target in step S1312, the diagnosis range can be changed by dragging in step S1318 or step S1322 as in the above-described operation. Based on the changed scan schedule 1152, calculation and display are performed in step S1324, and a chart based on the newly changed scan schedule 1152 is displayed as shown in FIG.

  If the shooting schedule table 1162 or the scan condition table 1164 in FIG. 7 is selected as the change target instead of the chart, execution proceeds from step S1316 to step S1332 and step S1334, and a new numerical value is input. Subsequent to step S1334, a new input value is set as a scan condition in step S1336. For example, when the number of segments SEG in the scan condition table 1164 is clicked, the number of segments SEG in the scan condition table 1164 is changed, and the display color of the number of segments SEG changes in step S1314. And the item of the number of segments SEG can be changed. Next, when the number of segment numbers SEG is input, a newly input value is set as a new segment number SEG by executing steps S1334 and S1336.

  FIG. 14 is an image showing the progress of X-ray imaging accompanying execution of step S1400 in FIG. 4, and is displayed on monitor display device 246 based on the operations of X-ray imaging unit 420 and display control unit 432 in FIG. It is an image. In FIG. 14, points SP1 and SP2 indicate the current shooting progress.

  The points SP1 and SP2 have already passed the time t2, and the shooting 1 described in the shooting schedule table 1162 is displayed as “completed”. When the points SP1 and SP2 have passed the time t4, the shooting 2 described in the shooting schedule table 1162 is changed to the display of “completed”.

  FIG. 15 is a chart showing the volume scan 1134 and the volume helical scan (variable pitch) 1132 in contrast, and how much the imaging time can be shortened when the volume helical scan (variable pitch) 1132 is used. I can judge. The volume helical scan (variable pitch) 1132 also scans the table run-up section, so that the total scan time can be shortened compared to the normal volume scan scan plan. Volume scan 1134 and volume helical scan (variable pitch) 1132 have advantages and disadvantages, respectively, and are preferably selected on a case-by-case basis.

  By displaying the volume scan 1134 and the volume helical scan (variable pitch) 1132 in comparison with each other as shown in FIG. 15, an appropriate selection can be made. Further, in FIG. 15, an icon for selecting a volume scan 1134 and a volume helical scan (variable pitch) 1132 is displayed, and in FIG. 15, the icon of the volume helical scan (variable pitch) 1132 is “ON”, while the volume is selected. The icon of the scan 1134 is “OFF”, and the volume scan 1134 and the volume helical scan (variable pitch) 1132 are selected. As described above, since the icon indicating which one of the photographing is selected is displayed in accordance with the chart for comparing the volume scan 1134 and the volume helical scan (variable pitch) 1132, there is an effect that the operation becomes easy.

  100 X-ray CT system, 102 Subject, 106 ECG, 120 gantry, 122 aperture, 124 rotating disk, 126 X-ray source, 142 X-ray control device, 144 gantry control device, 146 bed control device, 148 data Collecting device (DAS), 200 Arithmetic control unit 2, 212 CT control unit, 214 Image processing unit, 218 Reconstruction calculation unit, 222 Central processing unit, 224 Main memory, 226 Data recording device, 242 Input / output processing unit, 244 Display Memory, 246 Monitor display device, 250 bus line, 252 External input device, 254 mouse, 262 Network adapter, 264 network, 268 External database, 300 bed, 302 table, 304 lift unit, 412 scanogram shooting unit, 414 shooting schedule setting unit , 416 Imaging condition setting unit, 418 Synchronization condition calculation unit, 419 Scan data calculation unit, 420 X-ray imaging unit, 422 Image reconstruction unit, 432 Display control unit, 434 Recording control unit, 436 External connection control unit , 438 X-ray control unit, 442 Gantry control unit, 444 Sleeper movement control unit, 1102 Scanogram, 1152, 1154 Scan schedule, 1162 Scanning schedule table, 1164 Scan condition table, 1166, 1167, 1168 icon

Claims (12)

A table that moves in the body axis direction of the subject, an X-ray source that irradiates the subject with X-rays, and the X-ray source, and the X-ray source is based on a control command. A rotating disk that rotates the X-ray source so as to rotate around the X-ray source, an X-ray detector that detects X-rays transmitted through the subject, and collects projection data based on the output of the X-ray detector In an X-ray CT apparatus comprising an image processing unit for reconstructing an X-ray image based on collected projection data, and an input / output device having a display device and an input device,
A synchronization condition calculation unit that calculates the movement condition of the table that enables the collection of the projection data synchronized with the movement of the heart based on the information on the movement of the heart of the subject and the imaging conditions input from the input device. When,
A display control unit that displays the movement condition of the table calculated by the synchronization condition calculation unit on the display device as a chart including a body axis and a time axis;
An X-ray CT apparatus, further comprising: a couch moving speed control unit that controls movement of the table according to a moving condition of the table displayed on the chart. In the X-ray CT apparatus according to claim 1,
The display control unit displays a photographing range along the body axis, displays a moving time of the table along the time axis, and corresponds to the table corresponding to the photographing range and the moving time of the table. Display a graph based on the movement speed of
By changing the graph based on the moving speed of the table, the display control unit changes the moving time of the table,
The X-ray CT apparatus, wherein the bed movement speed control unit controls movement of the table based on a table movement condition obtained from the changed graph. In the X-ray CT apparatus according to claim 1,
The display control unit displays a photographing range along the body axis, displays a moving time of the table along the time axis, and corresponds to the table corresponding to the photographing range and the moving time of the table. Display a graph based on the movement speed of
When the display of the movement time of the table is changed, the display control unit changes the graph based on the movement speed of the table based on the change of the display of the movement time,
The X-ray CT apparatus, wherein the bed movement speed control unit controls movement of the table based on the changed table movement condition. In the X-ray CT apparatus according to claim 1,
The scanogram display unit further includes a scanogram display unit that displays a scanogram along the body axis of the chart, displays an imaging range on the scanogram, and displays the table on the chart corresponding to the imaging range. An X-ray CT apparatus, characterized in that a graph showing the movement state of is displayed.   In the X-ray CT apparatus according to claim 1, by changing the imaging range displayed on the scanogram, the graph representing the movement state of the table is changed corresponding to the changed imaging range, The bed movement speed control unit controls movement of the table based on the changed graph. In the X-ray CT apparatus according to claim 1,
In addition to the display of the chart, data representing the shooting state is displayed by the display control unit,
When the graph constituting the chart is changed, the displayed data indicating the shooting state is changed corresponding to the change of the chart, and the table is based on the changed data indicating the shooting state. The X-ray CT apparatus is characterized in that the movement or rotation of the rotating disk is controlled. In the X-ray CT apparatus according to claim 4,
A shooting schedule setting section is provided,
An imaging schedule having an asynchronous imaging range in which projection data is collected without being synchronized with a synchronous imaging range in which projection data is collected in synchronization with heart movement is input by the imaging schedule setting unit, and the synchronous imaging range is input to the scanogram And the asynchronous shooting range is displayed,
Based on the input of the imaging conditions of the synchronous imaging range, the movement condition of the table enabling the collection of the projection data synchronized with the motion of the heart is calculated by the synchronous condition calculation unit, and the synchronous imaging range is calculated by the display control unit A graph representing the movement state of the table is displayed on the chart,
Based on the input of shooting conditions of the asynchronous shooting range, a graph representing the movement state of the table of the asynchronous shooting range is displayed on the chart,
Based on the input shooting schedule, corresponding to the time axis constituting the chart, a graph representing a movement state of the table in the synchronous photographing range and a graph representing a movement state of the table in the asynchronous photographing range Arranged,
Based on the graph representing the movement state of the table in the synchronous photographing range arranged corresponding to the time axis and the graph representing the movement state of the table in the asynchronous photographing range, the table moves the bed movement speed control. An X-ray CT apparatus, characterized in that X-ray imaging is performed by being controlled by a unit. In the X-ray CT apparatus according to claim 1, the number of segments is input as an imaging condition,
The synchronization condition calculation unit calculates the movement condition of the table that enables the collection of the projection data synchronized with the motion of the heart based on the input number of segments,
The display control unit displays the movement condition of the table calculated by the synchronization condition calculation unit as a graph on the chart,
When the input number of segments is changed, the synchronization condition calculation unit calculates a movement condition of the table that enables the collection of the projection data synchronized with the motion of the heart based on the changed number of segments. ,
The display control unit compares the graph of the movement condition of the table before the change calculated by the synchronization condition calculation unit with the graph of the movement condition of the table after the change and displays the graph on the chart,
When the number of segments is determined, the bed moving speed control unit controls the movement of the table based on the table moving condition based on the determined number of segments. . In the X-ray CT apparatus according to claim 1,
The synchronization condition calculation unit calculates a range of change in heart rate that enables the collection of the projection data synchronized with the motion of the heart based on the number of segments input,
The display control unit displays a heart rate range calculated by the synchronization condition calculation unit as a graph,
When the heart rate condition is selected, the movement condition of the table based on the selected heart rate condition is calculated,
The bed movement speed control unit controls movement of the table based on the calculated movement condition. In the X-ray CT apparatus according to claim 1,
When shooting is performed based on the shooting conditions displayed on the chart, the display control unit performs a display indicating the shooting progress corresponding to the time axis of the chart, and the display indicating the shooting progress is the An X-ray CT apparatus, which moves in accordance with the time axis of the chart based on the progress of imaging. A table that moves in the body axis direction of the subject, an X-ray source that irradiates the subject with X-rays, and the X-ray source, and the X-ray source is based on a control command. A rotating disk that rotates the X-ray source so as to rotate around the X-ray source, an X-ray detector that detects X-rays transmitted through the subject, and collects projection data based on the output of the X-ray detector An X-ray CT apparatus imaging method used in an X-ray CT apparatus comprising: an image processing unit that reconstructs an X-ray image based on the collected projection data; and an input / output device having a display device and an input device Because
A first step of receiving information of the subject's heart movement;
A second step of receiving imaging conditions from the input device;
Based on the imaging conditions received in the second step, a third step of calculating the table movement conditions that enable the collection of the projection data synchronized with the motion of the heart,
A fourth step of displaying the movement condition of the table calculated by the synchronization condition calculation unit as a chart including a body axis and a time axis;
An X-ray CT apparatus imaging method, wherein X-ray CT imaging is performed by controlling the movement of the table according to the table moving conditions displayed on the chart. In the imaging method of the X-ray CT apparatus according to claim 11,
Further, when the display content of the chart is changed, the moving condition of the table is changed based on the changed content, and photographing is performed based on the changed moving condition of the table. To do X-ray CT.

Images