JP5290501B2 - X-ray CT system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recognize a region from a scout image (a scanogram) of an X-ray CT apparatus and to set a condition for photography (a protocol) suitable for the region. <P>SOLUTION: The region is automatically recognized from the quantity of geometric characteristics of the scout image (the scanogram), and at least one or a plurality of characteristic points are extracted. The region of the subject is automatically recognized based on the characteristic points, and the condition for photography (the protocol) suitable for the recognized region is set or adjusted from among previously registered conditions for photography (protocols). Alternatively, a candidate for the condition for photography (the protocol) suitable for the region is recommended, and the operator can be made to select or adjust the condition. Accordingly, the accuracy of setting of the condition for photography is improved, and as a result, the useless exposure caused by the false setting of the condition for photography can be prevented. Furthermore, the standby time for photography can be reduced by the efficient setting of the condition for photography. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an X-ray CT (Computed Tomography) imaging method and an X-ray CT apparatus in a medical X-ray CT apparatus or an industrial X-ray CT apparatus, and relates to a region range or inspection from a scout image (scanogram image). The present invention relates to a CT apparatus that recognizes a power range and automatically sets imaging conditions for the region or examination range, or raises imaging condition candidates to assist an operator in setting imaging condition candidates.

Conventionally, a scout image (scanogram image) is visually observed, an operator determines a range of a region and a range to be inspected, sets an imaging range, and simultaneously sets appropriate imaging conditions. Or it selected from the imaging condition group previously prepared in CT apparatus (for example, refer patent document 1). For this reason, the possibility of an operator's setting operation mistake, misunderstanding of judgment, etc. was not zero, which was a problem from the viewpoint of an operation error.
JP 2005-80748 A

  However, from the scout image (scanogram image), a plurality of feature points of the subject are found, and the examination range of the subject, the region inside the subject are estimated based on the feature points, or the feature points are newly detected by the detection algorithm. It is possible to extract and estimate a place to set the photographing condition. As a result, the photographing conditions can be set accurately.

  Therefore, an object of the present invention is to provide a scout image (scanogram image) of an X-ray CT apparatus having a two-dimensional area X-ray detector having a matrix structure represented by a multi-row X-ray detector or a flat panel X-ray detector. To provide an X-ray CT apparatus that defines a range for performing tomographic imaging of conventional scan (axial scan), cine scan or helical scan, and realizes setting of imaging conditions suitable for that part of the subject. .

  Another object of the present invention is to provide an X-ray CT apparatus that achieves the position of a subject and aligns the imaging conditions when there are imaging conditions registered in advance. .

  The present invention automatically recognizes a part from a geometric feature amount of a scout image (scanogram), extracts a point having at least one or a plurality of features, and determines a part of the subject based on the position of the feature point. It automatically recognizes and sets imaging conditions (protocols) suitable for the part from imaging conditions (protocols) registered in advance or adjusts the imaging conditions. Or the candidate of imaging conditions (protocol) suitable for the part can be raised and the operator can select and adjust. As a result, the accuracy of setting the shooting conditions is improved, and as a result, unnecessary exposure due to incorrect setting of the shooting conditions is eliminated. Also provided is an X-ray CT apparatus or an X-ray CT imaging method characterized by realizing a reduction in imaging waiting time by increasing the efficiency of setting imaging conditions.

  In a first aspect, the present invention relates to an X-ray generator and an X-ray detector that detects X-rays relative to each other while subjecting the X-ray detector to a rotational motion around a rotation center therebetween. A scan mode that collects X-ray projection data transmitted through the X-ray, or an X-ray detector that detects X-rays relative to the X-ray generator is fixed at a certain rotation angle, and the subject in between is positioned on the body axis. X-ray data collection means having both data collection in the scout mode for collecting transmitted X-ray projection data while moving in the direction, image reconstruction means for reconstructing the projection data collected from the X-ray data collection means, In an X-ray CT apparatus comprising: an image display means for displaying a reconstructed tomographic image; and an imaging condition setting means for setting various imaging conditions for tomographic imaging, the imaging condition setting means includes a geometry of a scout image. From the characteristic features Recognize and, to provide an X-ray CT apparatus characterized by including means for automatically setting the photographing conditions (protocol) suitable for the site.

  In the X-ray CT apparatus according to the first aspect, the scout image is subjected to image processing and image measurement, and it is determined from the geometric feature amount of the scout image which part of the subject the part imaged in the scout image is. , Select the imaging conditions (protocol) for the part and set it automatically, or adjust the number of images in the body axis direction (z-axis direction) and the imaging range of the selected imaging conditions Automatic setting can be made by slightly changing (Protocol).

In a second aspect, the present invention relates to an X-ray generator and an X-ray detector that detects X-rays relative to each other while subjecting the X-ray detector to a rotational motion around a rotation center between them. A scan mode that collects X-ray projection data transmitted through the X-ray, or an X-ray detector that detects X-rays relative to the X-ray generator is fixed at a certain rotation angle, and the subject in between is positioned on the body axis. X-ray data collection means having both data collection in the scout mode for collecting transmitted X-ray projection data while moving in the direction, image reconstruction means for reconstructing the projection data collected from the X-ray data collection means, In an X-ray CT apparatus comprising: an image display means for displaying a reconstructed tomographic image; and an imaging condition setting means for setting various imaging conditions for tomographic imaging, the imaging condition setting means includes a geometry of a scout image. From the characteristic features Knowingly presents a candidate imaging conditions suitable for the site, to provide an X-ray CT apparatus characterized in that it comprises a means for the operator to select.

  In the X-ray CT apparatus according to the second aspect, the scout image is subjected to image processing and image measurement, and it is determined which part is the part imaged in the scout image from the geometric feature amount of the binary image. Several imaging condition (protocol) candidates are selected for the region and presented to the operator for confirmation or selection.

  In a third aspect, the present invention provides the X-ray CT apparatus according to claim 1 or 2, wherein the imaging condition setting unit extracts a feature amount of the projection data profile from the scout image, and the subject from the scout image An X-ray CT apparatus is provided that includes means for recognizing a region of the image, displaying candidates, and confirming or correcting an imaging condition by an operator.

  In the X-ray CT apparatus according to the third aspect, the projection data profile obtained from the peripheral distribution measurement of the scout image in the x direction, that is, the projection data profile obtained from the peripheral distribution measurement of the scout image in the AP direction (0 degree direction), Alternatively, the projection data profile obtained from the peripheral distribution measurement in the y direction of the scout image, that is, the projection data profile obtained from the peripheral distribution measurement in the LR direction (90-degree direction) is obtained, and the projection data profile is 2 under the condition of a certain threshold value or more. Extract the geometrical features such as the digitized z-direction start coordinates, z-direction end coordinates, and the center of gravity that is the first moment of the projection data profile to recognize the part of the subject, and the imaging conditions (protocol) for that part To the operator and let the operator confirm the shooting conditions (protocol), or manually correct or reset It can be. In other words, among the selected imaging conditions, the imaging condition (protocol) is adjusted by adjusting the number of images in the body axis direction (z-axis direction) and the imaging range of the subject and changing the imaging conditions (protocol) slightly. Can be modified.

  In a fourth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 3, wherein the imaging condition setting unit performs geometric feature extraction of a scout image, There is provided an X-ray CT apparatus including means for recognizing a region to be examined and selecting an imaging condition suitable for the region of the subject from previously registered imaging conditions.

  In the X-ray CT apparatus according to the fourth aspect, the projection data profile obtained from the peripheral distribution measurement in the x direction of the scout image, that is, the projection data profile obtained from the peripheral distribution measurement of the scout image in the AP direction (0 degree direction), Alternatively, the projection data profile obtained from the peripheral distribution measurement in the y direction of the scout image, that is, the projection data profile obtained from the peripheral distribution measurement in the LR direction (90-degree direction) is obtained, and the projection data profile is 2 under the condition of a certain threshold value or more. Extracts the geometrical features such as the digitized z-direction start coordinates, z-direction end coordinates, and the center of gravity that is the first moment of the projection data profile, recognizes the part of the subject, and registers it in the X-ray CT system in advance Select at least one of the recorded shooting conditions (protocols) and present it to the operator for confirmation by the operator or manually It can be a positive or reconfiguration.

  In a fifth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 4, wherein the imaging condition setting unit extracts a geometric feature amount from the scout image, and There is provided an X-ray CT apparatus characterized by including means for recognizing a region to be examined and optimizing the region of the subject from the viewpoint of X-ray exposure dose, image quality, and imaging time.

  In the X-ray CT apparatus according to the fifth aspect, the scout image is binarized, and the part imaged in the scout image is determined from the geometric characteristics of the binary image, and the part of the subject is determined. From the geometric information obtained from the scout image, for example, the projection data profile area, the size of the subject, the existing range, the amount of change in the projection data in the z direction, etc. Imaging conditions (protocols) taking into consideration exposure dose, image quality (noise level), and reduction of imaging time can be presented to the operator or automatically set.

  In a sixth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 5, wherein the image quality of each tomographic image reconstructed is evaluated to obtain a constant image quality. If not, an X-ray CT apparatus including a means for reconstructing an image is provided.

  In the X-ray CT apparatus according to the sixth aspect described above, when the imaging condition (protocol) image reconstruction condition is optimally determined based on the information obtained from the scout image, the tomographic image has the optimum image quality. It may not be. When displaying a tomographic image to correct this, if it is determined that sufficient image quality has not been obtained by evaluating the image quality of each tomographic image that has been reconstructed, take another image. Even without this, the image reconstruction condition of the projection data may be changed to improve the image quality. In this way, it is possible to determine the image quality of each tomographic image and display a tomographic image or a three-dimensional image using the improved tomographic image by reconstructing the image.

  In a seventh aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 6, wherein the image quality of the three-dimensional display image of the imaging region made from the tomographic image reconstructed is evaluated. An X-ray CT apparatus comprising means for reconstructing an image again when a certain image quality is not achieved. I will provide a.

  In the X-ray CT apparatus according to the seventh aspect, when the imaging conditions (protocols) and image reconstruction conditions are optimally determined based on the information obtained from the scout image, the 3D display image is displayed. There may be cases where the image quality is not optimal. When displaying a three-dimensional image to correct this, if the image quality of each tomographic image reconstructed is evaluated and it is determined that sufficient image quality has not been obtained, the image is taken again. In some cases, the image quality can be improved by changing the image reconstruction conditions of the projection data without performing the above. In this way, it is possible to determine the image quality of each tomographic image and perform tomographic image display or three-dimensional image display using the improved tomographic image by performing image reconstruction again.

  In an eighth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 7, wherein the imaging condition setting unit uses a density peripheral distribution of the scout image, and the region from the scout image. Provided is an X-ray CT apparatus including means for automatically setting imaging conditions (protocols) suitable for the above.

  In the X-ray CT apparatus according to the eighth aspect, the scout image is subjected to image processing and image measurement, and it is determined from the geometric feature amount of the scout image which part of the subject the part imaged in the scout image is. , Select the imaging conditions (protocol) for the part and set it automatically, or adjust the number of images in the body axis direction (z-axis direction) and the imaging range of the selected imaging conditions Automatic setting can be made by slightly changing (Protocol). Further, when extracting the geometric features of the image from the scout image and correcting the photographing condition (protocol), the alignment of the photographing condition (protocol) is important. In order to perform this stably, if the position information is extracted from the geometric feature using the density peripheral distribution information and the alignment is performed, the alignment can be performed stably.

  In a ninth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 8, wherein the imaging condition setting means uses a binarization process for the scout image, Provided is an X-ray CT apparatus including means for automatically setting an imaging condition (protocol) suitable for a part from an image.

  In the X-ray CT apparatus according to the ninth aspect described above, the imaging condition (protocol) is aligned using the density peripheral distribution information in the viewpoint of the above item 8, but the scout image is binarized and the binary periphery. Even if information is used, the alignment of imaging conditions (protocols) can be performed in the same manner.

  In a tenth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 9, wherein the imaging condition setting means performs a plurality of binarizations with a plurality of thresholds on a scout image. Provided is an X-ray CT apparatus including means for automatically setting an imaging condition (protocol) suitable for a part from a scout image using processing.

  In the X-ray CT apparatus according to the tenth aspect, in the viewpoint of the ninth aspect, a plurality of binarizations are performed based on a plurality of threshold values, and imaging conditions (protocols) are aligned at a plurality of reference positions. However, the alignment accuracy can be increased.

  In an eleventh aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 10, wherein the imaging condition setting means performs a logical operation on a binary image obtained by binarizing a scout image. There is provided an X-ray CT apparatus including means for automatically setting an imaging condition (protocol) suitable for a part from a scout image using a filter process.

  In the X-ray CT apparatus according to the eleventh aspect, in the viewpoints of the ninth and tenth aspects, binarization is performed after binarization or binarization using a plurality of threshold values when aligning imaging conditions. By using a logic filter for removing noise from the image, the accuracy of the image can be improved, and the accuracy of the alignment of the shooting conditions can be increased.

  In a twelfth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 11, wherein the imaging condition setting unit is configured to perform a region for a binary image obtained by binarizing a scout image. Provided is an X-ray CT apparatus including means for automatically setting an imaging condition (protocol) suitable for a part from a scout image using numbering processing.

  In the X-ray CT apparatus according to the twelfth aspect, in the viewpoints of the ninth, tenth, and eleventh aspects, binarization or binarization with a plurality of threshold values is performed when imaging conditions are aligned. By removing geometric noise such as the area value of each continuous area by area numbering as noise removal from the binarized image, the image accuracy is improved by removing the image noise, and the alignment accuracy of the shooting conditions Can be raised.

  In a thirteenth aspect, the present invention provides the X-ray CT apparatus according to any one of claims 1 to 12, wherein the imaging condition setting unit is a region for a binary image obtained by binarizing a scout image. Provided is an X-ray CT apparatus including means for automatically setting an imaging condition (protocol) suitable for a part from a scout image, which performs a numbering process and processes an area of a selected area number .

  In the X-ray CT apparatus according to the thirteenth aspect, according to the viewpoints of the ninth, tenth, eleventh, and twelfth aspects, binarization or two threshold values are used when aligning imaging conditions. After the digitization, the subject is extracted and the imaging conditions are aligned based on the geometric feature amount such as the area value of each continuous region with the region numbering, so that the alignment accuracy can be improved.

  According to the X-ray CT apparatus of the present invention, from the scout image (scanogram image) of the X-ray CT apparatus, a range for performing tomographic imaging of conventional scan (axial scan), cine scan or helical scan is determined, and the subject It is possible to realize the setting of imaging conditions suitable for the part.

  As another object of the present invention, when there are imaging conditions registered in advance, it is possible to obtain the position of the subject and align the imaging conditions.

Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.
FIG. 1 is a configuration block diagram of an X-ray CT apparatus according to an embodiment of the present invention. The X-ray CT apparatus 100 includes an operation console 1, an imaging table 10, and a scanning gantry 20.

  The operation console 1 collects X-ray detector data collected by the scanning device gantry 20 and an input device 2 that receives input from the operator, a central processing device 3 that performs preprocessing, image reconstruction processing, post-processing, and the like. Data acquisition buffer 5, monitor 6 that displays tomograms reconstructed from projection data obtained by preprocessing X-ray detector data, program, X-ray detector data, projection data, and X-ray tomogram And a storage device 7 for storing.

  The photographing condition is input from the input device 2 and stored in the storage device 7. FIG. 14 shows an example of the shooting condition input screen. An input button 13a for performing a predetermined input is displayed on the photographing condition input screen 13A. FIG. 14 shows a screen in which a scan tab is selected. When P-Recon is selected as the tab, the display for input is switched as shown in the lower part of FIG. A tomographic image 13b is displayed above the input button 13a, and a reconstruction area 13c is displayed below. Moreover, you may display biosignals, such as a respiration signal and a heart rate signal, as it is displayed on the upper right if necessary.

  The imaging table 10 includes a cradle 12 on which a subject is placed and taken in and out of the opening of the scanning gantry 20. The cradle 12 is moved up and down and linearly moved by the motor built in the imaging table 10.

  The scanning gantry 20 includes an X-ray tube 21, an X-ray controller 22, a collimator 23, a beam forming X-ray filter 28, a multi-row X-ray detector 24, a data acquisition system (DAS: Data Acquisition System) 25, A rotation unit controller 26 that controls the X-ray tube 21 rotating around the body axis of the subject, and a control controller 29 that exchanges control signals and the like with the operation console 1 and the imaging table 10 are provided. . The beam forming X-ray filter 28 has the thinnest filter thickness in the X-ray direction toward the center of rotation, which is the imaging center, and the filter thickness increases toward the periphery, making it possible to absorb more X-rays. It is an X-ray filter. For this reason, exposure of the body surface of the subject having a cross-sectional shape close to a circle or an ellipse can be reduced. The scanning gantry tilt controller 27 can tilt the scanning gantry 20 forward and backward in the z direction by about ± 30 degrees.

  The X-ray tube 21 and the multi-row X-ray detector 24 rotate around the rotation center IC. When the vertical direction is the y direction, the horizontal direction is the x direction, and the table and cradle traveling direction perpendicular to these are the z direction, the rotation plane of the X-ray tube 21 and the multi-row X-ray detector 24 is the xy plane. is there. The moving direction of the cradle 12 is the z direction.

  FIG. 2 is a diagram showing the geometrical arrangement of the X-ray tube 21 and the multi-row X-ray detector 24 from the xy plane, and FIG. 3 shows the geometric arrangement of the X-ray tube 21 and the multi-row X-ray detector 24. It is the figure which looked at arrangement | positioning from the yz plane. The X-ray tube 21 generates an X-ray beam called a cone beam CB. When the direction of the central axis of the cone beam CB is parallel to the y direction, the view angle is 0 degree.

The multi-row X-ray detector 24 has X-ray detector rows of J rows, for example, 256 rows in the z direction. Each X-ray detector row has I-channels, for example, 1024 X-ray detector channels in the channel direction.
In FIG. 2, the X-ray beam emitted from the X-ray focal point of the X-ray tube 21 is irradiated by the beam forming X-ray filter 28 so that more X-rays are generated at the center of the reconstruction area P and more at the periphery of the reconstruction area P. Less X-rays are emitted. After spatially controlling the X-ray dose in this way, the X-rays are absorbed by the subject existing inside the reconstruction area P, and the transmitted X-rays are converted into X-ray detector data by the multi-row X-ray detector 24. Collected as.

  In FIG. 3, the X-ray beam emitted from the X-ray focal point of the X-ray tube 21 is controlled in the slice thickness direction of the tomogram by the X-ray collimator 23, that is, the X-ray beam width becomes D at the rotation center axis IC. Thus, X-rays are absorbed by the subject existing in the vicinity of the rotation center axis IC, and the transmitted X-rays are collected as X-ray detector data by the multi-row X-ray detector 24.

The projection data collected by irradiating the subject with X-rays is A / D converted by the data acquisition device (DAS) 25 from the multi-row X-ray detector 24 and the data acquisition buffer 5 via the slip ring 30. Is input. The data input to the data collection buffer 5 is processed by the central processing unit 3 according to the program in the storage device 7, reconstructed into a tomographic image, and displayed on the monitor 6. In this embodiment, the multi-row X-ray detector 24 is applied, but a two-dimensional X-ray area detector having a matrix structure represented by a flat panel X-ray detector can also be applied. A row x-ray detector can be applied.
(Operation flowchart of X-ray CT system)
FIG. 4 is a flowchart showing an outline of the operation of the X-ray CT apparatus of the present embodiment.
In step P1, the subject is placed on the cradle 12 and aligned. The subject placed on the cradle 12 aligns the center position of the slice light of the scanning gantry 20 with the reference point of each part.

  In step P2, a scout image (also called a scano image or a fluoroscopic image) is collected. Scout images can usually be taken at 0 and 90 degrees. Depending on the part, there may be only a 90-degree scout image, such as the head. In scout imaging, the X-ray tube 21 and the multi-row X-ray detector 24 are fixed, and the X-ray detector data is collected while the cradle 12 is moved linearly. Details of scout image shooting will be described later with reference to FIG.

  In step P3, shooting conditions are set while displaying the position and size of the tomographic image to be shot on the scout image. In the present embodiment, a plurality of scan patterns such as a conventional scan (axial scan), a helical scan, a variable pitch helical scan, and a helical shuttle scan are provided. Conventional scanning is a scanning method in which projection data is acquired by rotating the X-ray tube 21 and the multi-row X-ray detector 24 each time the cradle 12 is moved at a predetermined interval in the z-axis direction. The helical scan is an imaging method in which projection data is collected by moving the cradle 12 at a constant speed while the data collection system including the X-ray tube 21 and the multi-row X-ray detector 24 rotates. The variable pitch helical scan is an imaging method that collects projection data by changing the speed of the cradle 12 while rotating the data acquisition system consisting of the X-ray tube 21 and the multi-row X-ray detector 24 as in the helical scan. . Like the helical scan, the helical shuttle scan accelerates and decelerates the cradle 12 while rotating the data acquisition system consisting of the X-ray tube 21 and the multi-row X-ray detector 24, and the positive direction of the z axis or the z axis This is a scanning method in which projection data is collected by reciprocating in the negative direction. When these multiple radiographs are set, the X-ray dose information as a whole is displayed. In the cine scan, when the number of rotations or time is entered, X-ray dose information for the input number of rotations or the input time in the region of interest is displayed.

  In step P4, tomographic imaging is performed. Details of tomographic imaging and image reconstruction will be described later with reference to FIG. In step P5, the tomographic image reconstructed is displayed. In Step P6, a tomographic image continuously taken in the z direction is used as a three-dimensional image to display a three-dimensional image as shown in FIG.

15 shows volume rendering 3D image display method 40, 3D MIP (Maximum Intensity Projection) image display method 41, MPR (Multi Plain Reformat) image display method 42, and 3D reprojection image display method. Indicates. Various image display methods can be appropriately used depending on the purpose of diagnosis.
(Operation flowchart of tomography and scout imaging)
FIG. 5 is a flowchart showing an outline of tomographic and scout image capturing operations of the X-ray CT apparatus 100 of the present invention.
In step S1, the helical scan is performed by rotating the X-ray tube 21 and the multi-row X-ray detector 24 around the subject and moving the cradle 12 on the imaging table 10 in a straight line while the X-ray detector data data Perform the collection operation. Z-direction coordinate position in X-ray detector data D0 (view, j, i) (j = 1 to ROW, i = 1 to CH) represented by view angle view, detector row number j, and channel number i Ztable (view) is added to collect data within a certain range of speed.

  This z-direction coordinate position may be added to the X-ray projection data, or may be used in association with the X-ray projection data as a separate file. The information on the coordinate position in the z direction is used when X-ray projection data is reconstructed into a three-dimensional image during helical shuttle scanning or variable pitch helical scanning. Further, by using it at the time of helical scan, conventional scan (axial scan), or cine scan, it is possible to improve the accuracy of the tomographic image reconstructed and improve the image quality.

  As the z-direction coordinate position, the position control data of the cradle 12 of the imaging table 10 may be used, or the z-direction coordinate position predicted at each time predicted from the imaging operation set when the imaging condition is set.

  In the variable pitch helical scan or helical shuttle scan, in addition to collecting data in a constant speed range, data collection is also performed during acceleration and deceleration.

  In conventional scan (axial scan) or cine scan, X-ray detector data is collected by rotating the data acquisition system one or more times while the cradle 12 on the imaging table 10 is fixed at a certain z-direction position. Do. If necessary, after moving to the next position in the z direction, the data acquisition system is rotated once or more times to collect data of X-ray detector data.

  In scout imaging, the X-ray tube 21 and the multi-row X-ray detector 24 are fixed, and the data collection operation of the X-ray detector data is performed while the cradle 12 on the imaging table 10 is moved linearly. .

  In step S2, the X-ray detector data D0 (view, j, i) is preprocessed and converted into projection data. FIG. 6 shows specific processing for the preprocessing in step S2. In step S21, offset correction is performed. In step S22, logarithmic conversion is performed. In step S23, X-ray dose correction is performed. In step S24, sensitivity correction is performed.

  In the case of scout imaging, the pre-processed X-ray detector data can be displayed by matching the pixel size in the channel direction and the pixel size in the z direction, which is the linear movement direction of the cradle 12, to the display pixel size of the monitor 6. Completed as a statue.

  Returning to FIG. 5, in step S3, beam hardening correction is performed on the preprocessed projection data D1 (view, j, i). In the beam hardening correction in step S3, the projection data subjected to the sensitivity correction in step S24 of the preprocessing S2 is D1 (view, j, i), and the data after the beam hardening correction in step S3 is D11 (view, Assuming j, i), the beam hardening correction in step S3 is expressed, for example, in a polynomial form as shown in the following (Formula 1). In the present embodiment, the multiplication operation is represented by “●”.

  At this time, since independent beam hardening correction can be performed for each j column of the detector, if the tube voltage of each data acquisition system differs depending on the imaging conditions, the X-ray energy characteristics of the detector for each column Differences can be corrected.

In step S4, z filter convolution processing for applying a filter in the z direction (column direction) to the projection data D11 (view, j, i) subjected to beam hardening correction is performed.
That is, the projection of the multi-row X-ray detector D11 (view, j, i) (i = 1 to CH, j = 1 to ROW) subjected to beam hardening correction after preprocessing in each view angle and each data acquisition system For example, a filter with a column direction filter size of 5 columns as shown in (Formula 2) and (Formula 3) below is applied to the data in the column direction.

  The corrected detector data D12 (view, j, i) is as shown in (Formula 4) below.

It becomes. If the maximum value of the channel is CH and the maximum value of the column is ROW,
The following (Formula 5) and (Formula 6) are obtained.

  Further, when the column direction filter coefficient is changed for each channel, the slice thickness can be controlled in accordance with the distance from the image reconstruction center. In general, in the tomogram, the slice thickness is thicker in the peripheral part than in the reconstruction center. For this reason, the filter coefficient can be changed between the central portion and the peripheral portion, and the slice thickness can be made substantially uniform in both the peripheral portion and the image reconstruction central portion. For example, by changing the column direction filter coefficient between the central part and the peripheral part, the width of the column direction filter coefficient is changed widely near the central channel, and the width of the column direction filter coefficient is changed near the peripheral channel. If it is changed as much as possible, the slice thickness can be made substantially uniform both at the periphery and at the image reconstruction center.

  In this way, by controlling the column direction filter coefficients of the central channel and the peripheral channel of the multi-row X-ray detector 24, the slice thickness can also be controlled at the central portion and the peripheral portion. When the slice thickness is slightly reduced with the row direction filter, both artifacts and noise are greatly improved. Thereby, artifact improvement and noise improvement can also be controlled. That is, it is possible to control the tomographic image reconstructed, that is, the image quality in the xy plane. In another embodiment, a thin slice thickness tomographic image can be realized by using a column direction (z direction) filter coefficient as a deconvolution filter.

  In step S5, reconstruction function superimposition processing is performed. That is, the Fourier transform (Fourier Transform) for transforming the projection data into the frequency domain is performed, the reconstruction function is multiplied, and the inverse Fourier transform is performed. In reconstruction function superimposition processing S5, if the projection data after the z filter convolution processing is D12, the projection data after the reconstruction function convolution processing is D13, and the reconstruction function to be superimposed is Kernel (j), the reconstruction function convolution processing Is expressed as (Equation 7) below. In the present embodiment, the convolution calculation is represented by “*”.

That is, since the reconstruction function kernel (j) can perform an independent reconstruction function superimposing process for each j column of the detector, the difference in noise characteristics and resolution characteristics for each column can be corrected.
In step S6, three-dimensional backprojection processing is performed on the projection data D13 (view, j, i) subjected to reconstruction function superimposition processing to obtain backprojection data D3 (x, y, z). The image to be reconstructed is a three-dimensional image reconstructed on a plane perpendicular to the z axis and on the xy plane. The following reconstruction area P is assumed to be parallel to the xy plane. This three-dimensional backprojection process will be described later with reference to FIG.

In step S7, post-processing such as image filter superimposition and CT value conversion is performed on the backprojection data D3 (x, y, z) to obtain a tomographic image D31 (x, y, z).
In post-processing image filter superimposition processing, the tomographic image after three-dimensional backprojection is D31 (x, y, z), and the data after image filter convolution is D32 (x, y, z), the xy plane which is the tomographic image plane If the two-dimensional image filter to be superimposed at is Filter (z), the following (Formula 8) is obtained.

That is, since independent image filter superimposing processing can be performed for each tomographic image at each z-coordinate position, differences in noise characteristics and resolution characteristics for each column can be corrected.
Alternatively, the following image space z-direction filter convolution process may be performed after the two-dimensional image filter convolution process. The image space z-direction filter convolution process may be performed before the two-dimensional image filter convolution process. Furthermore, a three-dimensional image filter convolution process may be performed to produce an effect that serves as both the two-dimensional image filter convolution process and the image space z-direction filter convolution process.

  In the image space z-direction filter convolution processing, the tomographic image subjected to the image space z-direction filter convolution processing is D33 (x, y, z), and the tomographic image subjected to the two-dimensional image filter convolution processing is D32 (x, y, z). Then, the following (Formula 9) is obtained. However, v (i) is an image space z-direction filter coefficient having a width in the z direction of 2l + 1, and is a coefficient sequence as shown in the following (Equation 10).

In the helical scan, the image space filter coefficient v (i) may be an image space z-direction filter coefficient that does not depend on the z-direction position. However, when using conventional scanning (axial scan) or cine scan using a two-dimensional X-ray area detector 24 or multi-row X-ray detector 24 with a wide detector width in the z-direction, the image space z-direction filter coefficient It is preferable to use an image space z-direction filter coefficient depending on the position of the X-ray detector column in the z-direction for v (i). This is because it is more effective because detailed adjustment depending on the column position of each tomographic image can be performed. The obtained tomographic image is displayed on the monitor 6.
(3D back projection process flowchart)
FIG. 7 shows details of step S6 of FIG. 5, and is a flowchart of the three-dimensional backprojection process.

In the present embodiment, the image to be reconstructed is reconstructed into a three-dimensional image on a plane perpendicular to the z axis and on the xy plane. The following reconstruction area P is assumed to be parallel to the xy plane.
In step S61, attention is paid to one view in all views necessary for image reconstruction of the tomogram (that is, a view of 360 degrees or a view of “180 degrees + fan angle”). Projection data Dr corresponding to each pixel is extracted.

  Here, projection data Dr will be described with reference to FIGS. 8A and 8B to FIG. 8 (a) and 8 (b) are conceptual diagrams showing the projection of lines on the reconstruction area in the X-ray transmission direction. FIG. 8 (a) is the xy plane, and FIG. 8 (b) is yz. A plane is shown. FIG. 9 is a conceptual diagram showing each line of the image reconstruction plane projected onto the X-ray detector surface.

  As shown in FIGS. 8 (a) and 8 (b), a 512 × 512 pixel square region parallel to the xy plane is used as a reconstruction region P, and pixel rows L0, y parallel to the x axis where y = 0 = 63 pixel column L63, y = 127 pixel column L127, y = 191 pixel column L191, y = 255 pixel column L255, y = 319 pixel column L319, y = 383 pixel column L383, y = 447 Pixel column L447, pixel column L511 of y = 511 is taken as a column. Then, if the projection data on the lines T0 to T511 as shown in FIG. 9 obtained by projecting these pixel columns L0 to L511 onto the surface of the multi-row X-ray detector 24 in the X-ray transmission direction is extracted, the pixel columns L0 to L511 are extracted. Projection data Dr (view, x, y) of ~ L511. However, x and y correspond to each pixel (x, y) of the tomographic image.

  The X-ray transmission direction is determined by the X-ray focal point of the X-ray tube 21 and the geometric position of each pixel and the multi-row X-ray detector 24, but z of the X-ray detector data D0 (view, j, i). Since the coordinate z (view) is attached to the X-ray detector data as the table linear movement z-direction position Ztable (view), the X-ray detector data D0 (view, j, i) during acceleration / deceleration is also known. The X-ray transmission direction can be accurately determined in the data acquisition geometric system of the X-ray focus and multi-row X-ray detector.

  For example, a part of the line goes out of the channel direction of the multi-row X-ray detector 24, such as a line T0 in which the pixel row L0 is projected on the surface of the multi-row X-ray detector 24 in the X-ray transmission direction. In this case, the corresponding projection data Dr (view, x, y) is set to “0”. Further, if the projection is out of the z direction, the projection data Dr (view, x, y) is extrapolated.

In this way, projection data Dr (view, x, y) corresponding to each pixel in the reconstruction area P can be extracted as shown in FIG.
Returning to FIG. 7, in step S62, the projection data Dr (view, x, y) is multiplied by the cone beam reconstruction weighting coefficient to create projection data D2 (view, x, y) as shown in FIG.

  Here, the cone beam reconstruction weighting coefficient w (i, j) is as follows. In the case of fan beam image reconstruction, in general, when view = βa, a straight line connecting the focal point of the X-ray tube 21 and the pixel g (x, y) on the reconstruction area P (on the xy plane) is the center of the X-ray beam. When the angle formed with respect to the axis Bc is γ and the opposite view is view = βb, the following (Formula 11) is obtained.

  If the angles between the X-ray beam passing through the pixel g (x, y) on the reconstruction area P and the opposite X-ray beam and the reconstruction plane P are αa and αb, the cone beam reconstruction weighting coefficient depending on them Multiply and multiply by ωa and ωb to obtain backprojection pixel data D2 (0, x, y). In this case, (Formula 12) is obtained.

  Incidentally, the sum of the cone beam reconstruction weighting coefficients between the opposed beams is expressed by (Formula 13).

Cone angle artifacts can be reduced by multiplying and adding cone beam reconstruction weighting coefficients ωa and ωb.
For example, the cone beam reconstruction weighting coefficients ωa and ωb can be obtained by the following equations. Note that ga is a weighting coefficient for the view βa, and gb is a weighting coefficient for the view βb.

  When 1/2 of the fan beam angle is γmax, the following (Formula 14) to (Formula 19) are obtained.

For example, as an example of ga and gb, when max [] is a function that takes the larger value, the following (Formula 20) and (Formula 21) are obtained.

  Each pixel on the reconstruction area P is multiplied. For the distance coefficient, the distance from the focus of the X-ray tube 21 to the detector row j and channel i of the multi-row X-ray detector 24 corresponding to the projection data Dr is r0, and the distance from the focus of the X-ray tube 21 corresponds to the projection data Dr. (R1 / r0) 2 when the distance to the pixel on the reconstruction area P is r1.

In the case of parallel beam image reconstruction, each pixel on the reconstruction area P may be multiplied by only the cone beam reconstruction weight coefficient w (i, j).
In step S63, the projection data D2 (view, x, y) is added in correspondence with the pixels to the backprojection data D3 (x, y) that has been cleared in advance. FIG. 12 shows the concept of adding projection data D2 ((view, x, y) for each pixel.

  In step S64, steps S61 to S63 are repeated for all views necessary for image reconstruction of tomographic images (that is, views for 360 degrees or "180 degrees + fan angle"), and are necessary for image reconstruction. When all the views are added, the backprojection data D3 (x, y) shown in the left diagram of FIG. 12 can be obtained.

As described above, the flowchart of the three-dimensional backprojection process in FIG. 7 describes the image reconstruction area P shown in FIG. 8 as a square 512 × 512 pixels. However, it is not limited to this.
13 (a) and 13 (b) are conceptual diagrams showing a state in which a line on a circular image reconstruction area is projected in the X-ray transmission direction. FIG. 13 (a) shows an xy plane, and FIG. b) shows the yz plane.

As shown in FIGS. 13 (a) and 13 (b), the reconstruction area P may not be a square area of 512 × 512 pixels, but a circular area having a diameter of 512 pixels.
The general processing of the X-ray CT apparatus and the movement of each part in the present embodiment have been described above. Details of the operation of the present embodiment will be described below.

In general, imaging with a CT apparatus is performed as follows as shown in FIG.
Step P1: The subject is placed on the cradle 12 and aligned as shown in FIG.
Step P2: Scout image collection is performed as shown in FIG.

Step P3: The shooting conditions are set as shown in FIG.
Step P4: Tomography is performed as shown in FIG.
Step P5: A tomographic image is displayed as shown in FIG.

Step P6: Three-dimensional image display is performed as shown in FIG.
Conventionally, in step P3, an operator manually selects an appropriate imaging condition from pre-registered imaging conditions while looking at the scout image captured in step P2, and displays each tomographic image on the imaging condition scout image. Fine adjustment of the position, etc. is performed, and the tomographic image of the main scan in step P4 is performed. In the present embodiment, in this step P3, the automatic setting of the shooting conditions or the selection and adjustment of the shooting condition candidates that are conventionally set by the operator are performed, and the final setting is performed after the operator's confirmation and fine adjustment. When the imaging conditions are automatically set, each part of the subject is automatically recognized from the scout image.

FIG. 16 shows a basic operation flow in this embodiment.
In Step P11, scout image shooting is performed as shown in FIG.
In step P12, scout image reconstruction and display are performed as shown in FIG. Image reconstruction of the X-ray projection data of the scout image collected in step P11 is performed, and the scout image is displayed.

In step P13, scout image image feature quantity measurement is performed as shown in FIG. That is, the image feature quantity of the scout image is measured from the scout image or the X-ray projection data of the scout image.
In step P14, the photographing conditions are optimized as shown in FIG. Based on the input subject information (age, weight, height, measurement site, imaging conditions, etc.), the image feature value measured in Step P13 is judged to recognize the site and the location of the site. Perform measurement, etc., fine-tune the imaging conditions as an X-ray CT system, optimize imaging conditions to reduce exposure, optimize image quality, optimize imaging conditions to shorten imaging time, exposure dose at that time, exposure distribution The final shooting conditions are determined in consideration of the display and the presence / absence of synchronization signal input.

In step P15, tomographic image data is collected as shown in FIG. X-ray projection data acquisition of tomographic images is performed based on the imaging conditions determined in step P14.
In step P16, the tomographic image is reconstructed as shown in FIG. Image reconstruction of the X-ray projection data of the tomographic image collected in step P15 is performed.

In step P17, as shown in FIG. 16, a three-dimensional display of the imaging region is performed. If necessary, the tomographic images of the imaging regions obtained in step P16 are continuously arranged in the z direction, and three-dimensional display is performed.
In step P18, as shown in FIG. 16, it is determined whether the image quality evaluation has sufficient image quality. If YES, the process ends. If NO, go to step P19.

In step P19, the reconstruction conditions are optimized as shown in FIG.
In other words, in the above processing flow, the tomographic image display in step P16 and the three-dimensional image display in step P17 are evaluated. If the image quality is sufficient, the process ends. If the image quality is insufficient, the process proceeds to step P19. Then, the reconstruction conditions are further optimized for the captured scan data, and the tomographic image reconstruction is performed again. That is, the image reconstruction method of the projection data collected in step P15 is reviewed, and the process returns to the image reconstruction in step P16. Then, image reconstruction, tomographic image display, and three-dimensional image display are performed again. This is repeated until sufficient image quality is obtained.

  In such an operation flow, the flow of image processing and measurement processing for performing automatic recognition of a part in the imaging condition optimization in step P14 from the image feature amount measurement of the scout image in step P13 is shown below.

In each of the following embodiments, examples of automatically recognizing the following parts are shown.
Example 1: Example for automatically recognizing which part Example 2: Example for automatically recognizing the lung field Example 3: Example for automatically recognizing the neck Example 4: Example for automatically recognizing the head Example 5: Example for automatically recognizing the abdomen Example 6: Example for automatically recognizing the lower back part Example 7: Example for automatically recognizing the lower limb part In the following examples, selection is made based on the result of automatic recognition. An example is shown in which a plurality of types of imaging condition candidates for the subject are displayed and the operator selects them.

  Example 8: Example in which the operator selects from a plurality of shooting condition candidates selected from the result of automatic recognition

In the first embodiment, first, in order to set a photographing condition (protocol) from a scout image, it is necessary to know where the portion that has moved to the scout image is. In the present embodiment, which part of the following parts is determined from the scout image.
1． Lung field
2． neck
3． head
Four. abdomen
Five. waist
6． Lower limbs As shown in FIG. 17, in step T1, it is determined whether the skeleton ratio is high. If YES, the process goes to step T2, and if NO, the process goes to step T5.

As shown in FIG. 17, in step T2, it is determined whether the object is an ellipsoid in the x-axis direction. If YES, the process goes to step T3, and if NO, the process goes to step T10.
As shown in FIG. 17, in step T3, the AP direction scout image is binarized with the lung field threshold value, and it is determined whether the lung is present. If YES, go to step T4, if NO, step Go to T11.

As shown in FIG. 17, in step T4, it is determined that the region is a lung field, and the process ends.
As shown in FIG. 17, in step T5, one area is determined by looking at the scout image in the AP direction. If YES, the process goes to step T6, and if NO, the process goes to step T7.

As shown in FIG. 17, in step T6, it is determined whether the profile area is large. If YES, the process goes to step T8, and if NO, the process goes to step T9.
As shown in FIG. 17, in step T7, the lower limb is determined and the process ends.

As shown in FIG. 17, in step T8, the abdomen is determined and the process ends.
As shown in FIG. 17, in step T9, the neck is determined and the process ends.
As shown in FIG. 17, in step T10, the head is determined and the process ends.

As shown in FIG. 17, in step T11, the waist is determined and the process ends.
In particular, the threshold value of the skeletal ratio at step T1 in this process, the threshold value of the outer circularity indicating the degree of distortion of the ellipsoid at step T2 (explained in detail in Examples 2, 3, 4, 5, 6, and 7 later), These thresholds, such as the threshold for detecting lung fields from the scout image of T3 and the threshold for the profile area of step T6, are statistically determined in advance from the age, sex, weight, and height of the subject. The decision logic of each part from the image can be moved more accurately.

Each part can be determined from the scout image in the above-described determination process flow. The details of the skeleton ratio will be described in Examples 2, 3, 4, 5, 6, and 7 below.
It should be noted that such decision logic is not limited to one but may be considered in various ways. Incidentally, FIG. 33 and FIG. 34 show other examples of similar determination logic.

As shown in FIG. 18, in step T21, the AP direction scout image is binarized with the threshold value of the lung field, and it is determined whether the lung is present. If NO, the process goes to step T22, and if YES, step T17. Go to.

As shown in FIG. 18, in step T22, one area is determined from the scout image in the AP direction. If YES, the process goes to step T23, and if NO, the process goes to step T28.
As shown in FIG. 18, in step T23, a determination is made as to whether the area profile is large. If YES, the process goes to step T24, and if NO, the process goes to step T29.

As shown in FIG. 18, in step T24, it is determined whether the skeleton ratio is large. If YES, the process goes to step T25, and if NO, the process goes to step T30.
As shown in FIG. 18, in step T25, it is determined whether the object is an ellipsoid in the x-axis direction. If YES, the process goes to step T26, and if NO, the process goes to step T21.

As shown in FIG. 18, in step T26, it is determined as a waist and the process ends.
As shown in FIG. 18, in step T27, the region is determined to be a lung field and the process ends.
As shown in FIG. 18, in step T28, the lower limb is determined and the process ends.

As shown in FIG. 18, in step T29, the neck is determined and the process ends.
As shown in FIG. 18, in step T30, the abdomen is determined and the process ends.
As shown in FIG. 18, in step T31, the head is determined and the process ends.

  Also in this determination logic, the threshold value of the skeletal ratio at step T1 and the circularity indicating the degree of distortion of the ellipsoid at step T2 (details will be described later in Examples 2, 3, 4, 5, 6, and 7) These thresholds, such as threshold values for detecting lung fields from the scout image at step T3 and threshold values for profile area at step T6, should be statistically determined in advance from the age, sex, weight, and height of the subject. Thus, the determination logic of each part from the scout image can be moved more accurately.

  In addition, if the operator finds that the result of automatic determination of each part from the scout image is wrong by not selecting the result of automatic determination at the imaging condition (protocol) selection stage, the correct answer by the operator If information is taken in and each threshold value of this determination logic can be corrected by learning, a more accurate determination logic can be constructed. In this way, when learning is performed and the threshold value is changed, the decision logic is different from the type in which the decision logic is two-dimensionally expanded in a tree structure (Tree structure) as in Decision Example 1, as in Decision Example 2. It is easier to determine the threshold value to be changed for the one-dimensionally extending type.

  As described above, the type of the imaging region of the subject and the size of the imaging region can be recognized. Recommended imaging conditions (protocols) are usually prepared for each imaging site, such as the head, abdomen, lung field, heart, lower limbs, etc., and for each examination purpose. Match the size and position of the imaging region of the subject measured above. The imaging conditions thus created are presented to the operator, and after correction is made as necessary, imaging is performed.

In the first embodiment, an embodiment in which a lung field portion is automatically recognized from a scout image will be described.
The features on the scout image in the lung field include the following points as shown in FIGS. 19 (a) and 19 (b).
1． From the shoulder to the lung field, the outer shape is an ellipse that is long in the RL direction (x-axis direction).
2． After showing a large profile area from the shoulder to the lung field, the profile area becomes smaller in the lung field when proceeding in the z-axis direction. As the lung field ends, the profile area value increases again.
3． In the skeletal portion, the outline of the skeletal portion in the AP direction increases to the lung field as it advances in the z direction, and then decreases. The outline of the skeletal portion in the RL direction increases to the lung field as it advances in the z direction, and then decreases.

Now, the gray scale image of the scout image in the AP direction (y axis direction, 0 degree direction) is ga (x, y), and the gray image of the scout image in the RL direction (x axis direction, 90 degree direction) is gr (y, z).
In addition, a threshold at which the outer shape of the subject can be cut out is Th1, and a threshold at which the skeleton or bone part of the subject can be cut out is Th2.

The AP direction scout image ga (x, z) binarized with the threshold Th1 is defined as ba1 (x, z), and the RL direction scout image gr (y, z) is defined as br1 (y, z).
The scout image ga (x, z) in the AP direction binarized with the threshold Th2 is set to ba2 (x, z), and the scout image gr (y, z) in the RL direction is set to br2 (y, z).

  At this time, the outer shape La1 (z) in the AP direction and the outer shape Lr1 (z) in the RL direction are determined by the following (Formula 22) and (Formula 23). However, the matrix size of the tomographic image is N × N pixels, and x∈ [1, N] and y∈ [1, N].

  The AP direction outer shape La1 (z) and the RL direction outer shape Lr1 (z) are shown in FIG. 19 (a) and FIG. 19 (b) for easy understanding. And an outer shape 2 in the AP direction, an outer shape 1 in the RL direction, and an outer shape 2 in the RL direction. Even if it is divided into three line segments as shown in outline 2 in the AP direction, the sum of the length of the divided line segments and the sum of the number of pixels in the line segment is the image feature amount as the outline in the AP direction become.

  Further, the outer shape La2 (z) in the AP direction and the outer shape Lr2 (z) in the RL direction of the skeleton or bone are determined by the following (Equation 24) and (Equation 25).

The profile area Pa (z) can be determined by any one of the following (Equation 26) and (Equation 27).

  Further, the profile area Pb (z) of the skeleton or the bone is determined by the following (Equation 28) and (Equation 29). That is, it is the sum of the gray images of the scout image in the part of the skeleton or bone part that is equal to or greater than the threshold Th2.

FIG. 18 shows the image features on the scout images of the above-mentioned 1, 2, and 3 lung fields as image features.
In FIG. 20, the AP direction outline, RL direction outline, profile area, skeleton part AP direction outline, skeleton part RL direction outline, and skeleton profile area z-direction of each image feature amount in the lung field The change in the coordinate position is shown.

  As shown in Fig. 20, the AP direction outer shape value and the RL direction outer shape value show a small value in the neck with changes in the z-direction coordinate, but the value increases when entering the shoulder, and the lung field part But the value is large as well. Even if the lung field ends and enters the abdomen, the value is also large.

  Further, as shown in FIG. 20, the profile area value shows a small value in the neck as the z-direction coordinate position changes, but the value increases when entering the shoulder. In the lung field, since the CT value of the pixel inside the lung is low, the X-ray absorption coefficient is small. For this reason, the profile area value decreases when entering the lung field. When the lung field is over, the profile area value increases again.

  In addition, as shown in FIG. 20, the value of the skeleton or bone outer shape in the AP direction and the value of the skeleton or bone outer shape in the RL direction show a small value in the neck, but when entering the shoulder, The value is also large because there is a rib in the lung field, but the value decreases when the lung field ends with the end of the rib and enters the abdomen.

Further, as shown in FIG. 20, the profile area of the skeleton or the bone part shows a small value in the neck. It becomes larger at the shoulder, but the value decreases at the lung field.
Based on these changes in the image feature amounts, the flow of lung field imaging condition setting / imaging based on the lung field scout image is as shown in FIGS.

  In step P31, as shown in FIGS. 21 and 22, scout image projection data is collected in the 0 degree direction and the 90 degree direction. In the scout image projection data collection in the 0 degree direction and 90 degree direction in Step P31, the X-ray tube 21 and the multi-row X-ray detector 24 are fixed without rotating as in normal scout imaging, and the X-ray Scout image projection data acquisition can be performed by relatively moving the data acquisition system including the tube 21 and the multi-row X-ray detector 24 and the cradle 12 of the imaging table 10. Alternatively, scout imaging by helical scout scanning can be performed by performing helical scanning with low exposure X-rays at a fast helical pitch.

  In Step P32, as shown in FIGS. 21 and 22, image reconstruction of scout images in the 0 degree direction and the 90 degree direction is performed. In the image reconstruction of the scout image in the 0 degree direction and the 90 degree direction in Step P32, the time series obtained from the X-ray tube 21 and the multi-row X-ray detector 24 are reconstructed as in the normal scout image reconstruction. Image reconstruction can be performed by arranging X-ray projection data in the z-coordinate direction and adding, averaging, or weighted addition of X-ray projection data having the same or nearby z-direction coordinates as necessary. Alternatively, tomographic images by helical scout scanning are reconstructed, and the tomographic image at each z-direction coordinate position is reprojected in the xy plane in the 0-degree direction or 90-degree direction, so that one line of each z-direction coordinate is Scout image data can be obtained and repeated for all z-direction coordinates to reconstruct the scout image.

  In step P33, as shown in FIG. 21 and FIG. 22, binarization is performed with a threshold value Th1 that indicates the body outline. The threshold value Th1 of the external shape of the subject in step P33 may be a value determined in advance for each region, or may be a value common to all regions. Alternatively, the threshold value Th1 may be set to a floating threshold value so that the shape, area value, or number of continuous regions of the subject is determined to some extent.

  In step P34, as shown in FIGS. 21 and 22, binarization is performed with a threshold Th2 at which a bone can be detected. The threshold value Th2 for detecting a bone in step P34 may be a value set in advance for each site, or may be a threshold value common to all sites. Alternatively, the threshold value Th1 may be set to a floating threshold value so that the shape, area value, or number of continuous regions of the subject is determined to some extent.

  In step P35, as shown in FIGS. 21 and 22, density peripheral distribution (profile area) Pa (z) in the x direction of the scout image is measured. In the x direction density distribution measurement of the scout image in step P35, as shown in FIG. 24, for example, by measuring the density peripheral distribution in the x direction with respect to the scout image in the 0 degree direction, the profile of each z direction coordinate position The area value is determined.

In step P36, as shown in FIGS. 21 and 22, the x-direction and y-direction binary peripheral distributions La1 (z) and Lr1 (z) of the binary image binarized in step P33 are measured.
In step P36, the binary peripheral distribution measurement in the x direction of the binary image binarized with the threshold value Th1 that shows the external shape of the body is the AP direction external shape La1 (z), and the binary peripheral distribution measurement in the y direction The result is the outer shape Lr1 (z) in the RL direction. At this time, as shown in FIG. 24, for example, a binary peripheral distribution measurement in the x direction is performed on a scout image of a binary image binarized with a threshold Th1 that can cut out the outer shape of the subject in the 0 degree direction. This indicates that the outer shape La1 (z) in the AP direction at each z-direction coordinate position is obtained. Similarly, by performing binary peripheral distribution measurement in the x direction on the scout image of the binary image binarized with the threshold Th2 that can cut out the skeleton or bone part of the subject, AP at each z direction coordinate position The bone contour La2 (z) in the direction will be obtained.

In step P37, as shown in FIGS. 21 and 22, the x-direction and y-direction binarized peripheral distributions La1 (z) and Lr1 (z) of the binary image binarized in step P34 are measured.
In Step P37, the result of the binary peripheral distribution measurement in the x direction of the binary image binarized with the threshold value Th2 that can detect the bone is the outline La2 (z) of the skeleton or bone part in the AP direction, and 2 in the y direction. The result of the measurement of the distribution around the value is the outline Lr2 (z) of the skeleton or bone part in the RL direction.

  In step P38, as shown in FIG. 21 and FIG. 22, the position where Pa (z), La1 (z), and Lr1 (z) are suddenly detected is detected, and the z-direction coordinate position of the shoulder and zshoulder are detected. I do. Thereby, in step P38, the z-direction coordinate position zshoulder of the shoulder is known.

  In step P39, as shown in FIGS. 21 and 22, binarization is performed with a threshold value Th3 that allows the outer shape of the lung field to be known. The threshold value Th3 for knowing the outer shape of the lung in step P39 may be a value determined in advance for each region, or may be a value common to all regions. Alternatively, the threshold value Th1 may be set to a floating threshold value so that the shape, area value, or number of continuous regions of the lung field is determined to some extent.

In step P40, as shown in FIGS. 21 and 22, the upper limit position zlungs and the lower limit position zlunge of the lung field are detected.
In step P40, the upper limit zlungs of the lung field corresponding to the apex of the shoulder and the lower limit zlunge of the lung field are known. Thereby, the imaging range of the lung field can be aligned like [zshoulder, zlunge] or [zlungs, zlunge].

  In step P41, image noise is removed by a logical filter. FIG. 23 shows the flow of image noise removal processing by this logical filter. Image noise removal processing by the logic filter of FIG. 23 is as follows.

In step P411, as shown in FIG. 23, the contracting logic filter is applied N times. This eliminates the image noise of small isolated points.
In step P412, as shown in FIG. 23, the expanding logical filter is applied M times. As a result, the part other than the image noise returns to the original size. However, N = M may be satisfied. In this way, image noise of the binary image is removed by using the contraction and expansion of the logic filter.

Returning to FIGS. 21 and 22, in step P42, as shown in FIGS. 21 and 22, region numbering processing is performed. The continuous region with the region number includes the lung field region.
If binarization processing is performed with the threshold Th3 that allows the contour of the lung field to be determined in step P42, and region numbering processing is performed on the binary image, the result is as shown in FIG. Even if image noise removal is successfully performed in step P41, a background portion is extracted in addition to the lung field region. In order to remove the background portion, the image feature amount for each continuous region is obtained as follows, and only the lung field portion is recognized and extracted.

  In step P43, as shown in FIGS. 21 and 22, the image feature amount of each continuous region is measured. The image feature amounts at this time are as follows. The two-dimensional image processing includes area, ferret diameter, circularity, density sum, area ratio, and the like. In order to measure the area number of each continuous area, the density histogram of the area numbered image is obtained, and the number of pixels corresponding to each area number is the area of the number of pixels in the continuous area of each area number. It becomes. As shown in FIG. 25 (a), the ferret diameters lx and ly are determined from the minimum x coordinate xmin, the minimum y coordinate ymin, the maximum x coordinate xmax, and the maximum y coordinate ymax of the continuous area of each area number. Is obtained by the following (Equation 30) and (Equation 31).

  Further, as shown in FIG. 25 (b), the circularity C is obtained by the following (Equation 33) from the circumference L obtained by the contour extraction logical filter and the area S.

  In addition, as shown in FIG. 25 (c), the concentration sum D is obtained by the following (Formula 34).

  Further, as shown in FIG. 25 (d), the area ratio SR is obtained by the following (Formula 35).

In step P44, as shown in FIGS. 21 and 22, the image noise region is removed and the lung field region is extracted.
When the subject has been imaged at the correct position, the lung field should come to the center of the scout image and the background should come to the periphery of the scout image as shown in FIG. This feature can be used to determine whether it is the background or the lung field. For example, it is possible to determine whether or not the region is in the center of the scout image by determining the minimum x coordinate xmin, the minimum y coordinate ymin, the maximum x coordinate xmax, and the maximum y coordinate ymax of each continuous region. In addition, if the subject is a healthy person, the approximate size of the lung field can be predicted based on the weight, height, age, etc. of the subject. Good. In this way, it can be determined from the image feature amount whether the region is a lung field.

  In step P45, as shown in FIGS. 21 and 22, the imaging conditions (protocols) registered in advance are aligned with the positions of the lung fields. In step P45, the center of the imaging region and the size of the imaging region are set so that the imaging region can cover the lung field area obtained in step P44. At this time, the setting accuracy of the imaging region is further improved by considering both the lung field region obtained from the AP direction scout and the lung field region obtained from the RL direction scout. Other imaging conditions (protocols) such as a reconstruction function, a slice thickness, and a scanning speed may be determined in advance.

  In addition, the imaging range in the z direction is taken at a predetermined tomographic interval in the lung field from the upper limit value zlungs of the lung field corresponding to the apex of the lung to the lung bottom zlunge corresponding to the lower limit value of the lung field. It ’s fine. This is shown in the lung field imaging region of FIG. Also, as shown in FIG. 40, the lung field imaging region may be determined with a margin before and after the lung field imaging region in the z direction. Alternatively, the range from zshoulder that hits the shoulder to the lower limit zlungs of the lung field may be taken as an imaging range, and this interval may be taken at the tomographic image interval of the lung field. By setting the photographing conditions in this way, the photographing conditions (protocols) can be aligned.

  In step P46, as shown in FIGS. 21 and 22, the photographing condition (protocol) is displayed. In step P46, the user interface for displaying the imaging conditions of each candidate including a plurality of imaging conditions as shown in FIG. 43 is displayed on the imaging condition input screen of the monitor 6 of the X-ray CT apparatus 100 as shown in FIG. For example, it is displayed as a pop-up screen. If the operator determines that the imaging conditions are appropriate for imaging of the subject and there are candidates for imaging conditions that can be selected, the imaging condition candidates are selected from these imaging condition candidates. However, if there is no appropriate imaging condition for imaging the subject, the imaging condition is set by correcting the imaging condition (protocol) in the following Step P47.

  In FIG. 43, the determination result as to which part is shown in the first embodiment is displayed in the “subject part” window. In addition, the candidates for photographing conditions obtained in step P45 are shown in the “candidate 1” and “candidate 2” windows.

  For example, in this case, as shown in FIG. 40, only the lung field imaging region is shown as “candidate 1”, and the lung field imaging region with a margin in the z direction is set as “candidate 2”. . As a result, the operator has some choice.

  In step P47, as shown in FIGS. 21 and 22, the operator is asked whether the operator has been modified. If YES, the operator is modified in step P48. If NO, select one of the shooting condition candidates and go to Step P49. In step P47, it is necessary that the operator determines that the imaging conditions of the subject are not appropriate as the imaging conditions of the subject in the candidate imaging condition user interface including the plurality of imaging conditions displayed in step P46, and corrects the imaging conditions (protocol). In some cases, each item of the shooting conditions for each candidate can be clicked to select that item, and the number and selection mode can be corrected and reset.

In Step P49, as shown in FIGS. 21 and 22, the photographing condition is determined and set.
In step P49, the imaging conditions are determined from the imaging conditions selected by the operator in step P47 or step P48, or the imaging conditions partially corrected, and the imaging conditions are set as the X-ray CT apparatus 100.

In Step P50, photographing is performed as shown in FIGS.
In the imaging in step P50, the subject is imaged according to the imaging conditions set in step P49.

In step P51, as shown in FIGS. 21 and 22, tomographic image reconstruction is performed.
In step P51, according to the operation of the X-ray CT apparatus 100, the correct part of the subject can be imaged under the correct imaging conditions.

In step P52, as shown in FIGS. 21 and 22, tomographic image display is performed.
Thereby, a tomographic image of the correct part of the subject is displayed.
As described above, the imaging conditions can be determined by recognizing the shape of the subject. Using the image processing shown in FIG. 24, the binary image obtained by measurement, the binary peripheral distribution, and the gray scale peripheral distribution feature amount, it is possible to determine the part and measure the position of the part.

In the second embodiment, an embodiment in which the neck from the scout image is automatically recognized will be described.
Features on the scout image in the neck include the following points as shown in FIGS. 26 (a) and 26 (b).
1． In both the AP direction (y direction, 0 degree direction) and RL direction (x direction, 90 degree direction) scout images, the outer shape in the AP direction, the outer shape in the RL direction, and the profile area from the head to the shoulder These image feature amounts are all small, and are large when entering the shoulder.
2． The cross-sectional shape is not an ellipse but a circular shape.
3． In the outline of the skeleton part, both the AP direction and the RL direction are uniform from the head in the z direction. When entering the shoulder, both the AP direction and the RL direction increase.

In the cervical region, the following image feature amount of the following circularity is newly added.
The external circularity C (z) is determined by the following (Equation 36).

FIG. 27 shows the image features on the scout images of the necks 1, 2, and 3 described above as image feature amounts.
In FIG. 27, each of the image feature quantities of the AP direction outline, the RL direction outline, the profile area, the circularity of the cervical part, the AP direction outline of the skeleton part, the RL direction outline of the skeleton part, and the skeleton profile area in FIG. The change in the z-direction coordinate position is shown.

Based on these changes in image feature amounts, the flow of cervical imaging condition setting imaging by a cervical scout image is as shown in FIGS.
In step P61, as shown in FIGS. 41 and 42, scout image projection data is collected in the 0 degree direction and the 90 degree direction.

In Step P62, as shown in FIGS. 41 and 42, image reconstruction of scout images in the 0 degree direction and the 90 degree direction is performed.
In step P61 and step P62, scout image projection data collection and image reconstruction in the 0 degree direction and 90 degree direction are performed in the same manner as in steps P31 and P32 in FIGS.

In step P63, as shown in FIG. 41 and FIG. 42, binarization is performed with a threshold value Th1 that indicates the outer shape of the body, and binary peripheral distributions La1 (z) and Lr1 (z) in the x and y directions are measured.
In step P63, after binarization is performed with a threshold Th1 that indicates the outer shape of the body, the outer shape La1 in the AP direction (z) indicates the size of the outer shape in the AP direction as in (Equation 22) and (Equation 23). ) Measure the outer shape Lr1 (z) in the RL direction, which indicates the size of the outer shape in the RL direction. This measurement can be performed by measuring a binary marginal distribution. In Step P63, the scout image in the AP direction that was reconstructed with the threshold Th1 that shows the external shape of the subject's body was binarized, and the result of measuring the binary peripheral distribution in the x direction with the binarized binary image Is the outer shape La1 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the outer shape Lr1 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In step P64, as shown in FIGS. 41 and 42, binarization is performed with a threshold value Th2 at which bone can be detected, and binary peripheral distributions La2 (z) and Lr2 (z) in the x and y directions are measured.
In step P64, after binarization is performed with a threshold Th2 that indicates the outline of the skeleton or bone, the skeleton or bone showing the size of the bone outline in the AP direction as shown in (Equation 24) and (Equation 25). The outer shape La2 (z) in the AP direction of the bone part and the outer shape Lr2 (z) in the RL direction of the skeleton or the bone part indicating the size of the outer shape of the bone in the RL direction are measured. This can be done by measuring the binary marginal distribution. Step P64 binarizes the AP direction scout image reconstructed with a threshold Th2 that shows the skeleton or bone outline of the subject, and measures the binary peripheral distribution in the x direction using the binarized binary image The result is the bone outline La2 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the bone outline Lr2 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

  In Step P65, as shown in FIGS. 41 and 42, the density peripheral distribution (profile area) Pa (z) of the scout image is measured. In Step P65, the profile area Pa (z) can be obtained by measuring the peripheral density distribution in the x direction of the scout image in the AP direction. Further, the profile area Pr (z) can be obtained by measuring the peripheral density distribution in the y direction of the scout image in the RL direction.

Normally, Pa (z) and Pr (z) are substantially equal when the subject is present in the center of the tomographic imaging field, that is, near the rotation center of the X-ray data acquisition system. If the scout image has only one of the AP direction and the RL direction, either one is obtained as the profile area Pa (z).
If scout images in two directions of the AP direction and the RL direction are obtained, the average of Pa (z) and Pr (z) can be obtained and used as the profile area Pa (z). In this case, a more accurate profile area Pa (z) can be obtained.

  In step P66, as shown in FIG. 41 and FIG. 42, the external circularity C (z) is measured from the binary peripheral distributions La1 (z) and Lr1 (z). The external circularity C (z) in step P66 can be obtained from the external shape La1 (z) of the body in the AP direction and the external shape Lr1 (z) of the body in the RL direction, as shown in (Equation 38).

  In step P67, as shown in FIGS. 41 and 42, a binary image ba2 (x, z) binarized with a threshold value Th2 that can detect a scout image ga (x, z), gr (y, z) and a bone , Br2 (y, z), skeleton or bone profile area Pb (z) is measured. The method of obtaining the profile area of the skeleton or the bone part in Step P67 is as (Formula 28) and (Formula 29). If there is only one of the scout images in the AP direction or RL direction, the profile area of the skeleton or bone part is obtained by (Equation 28) if only the AP direction is used. If it is only in the RL direction, the profile area of the skeleton or bone is obtained by (Equation 29). If scout images in both the AP direction and the RL direction exist, the AP is usually used if the subject is in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system. The profile area Pb (z) of the skeleton or bone part in the direction and the profile area of the skeleton or bone part in the RL direction should be approximately equal. If scout images in two directions, AP direction and RL direction, are obtained, the average of two Pb (z) can be obtained and used as the profile area Pb (z) of the skeleton or bone. A more accurate one can be obtained.

In Step P68, as shown in FIGS. 41 and 42,
Falling La1s, rising La1e of external shape La1 (z) in the AP direction,
Falling Lr1s, rising Lr1e, outer shape Lr1 (z) in the RL direction,
Falling Pas, rising Pae of profile area Pa (z),
Falling Cs, rising Ce of external circularity C (z),
Falling La2s, rising La2e of external shape La2 (z) in the AP direction of the skeleton,
Falling Lr2s, rising Lr2e of external shape Lr2 (z) in the RL direction of the skeleton
Falling Pbs, rising Pbe of skeleton profile area Pb (z),
Measure. In Step P68, a cervical start point znecks and a cervical end point znecke in the z direction are obtained from these change points. In order to determine the start point znecks and end point znecke, it is possible to determine by using some of these change points, or it is possible to determine by using the average value of all of these change points, It can also be determined using all the weighted addition values of the change points, or can be determined using some weighted addition values of these change points.

  In step P69, as shown in FIGS. 41 and 42, the imaging conditions (protocols) registered in advance at the neck position are aligned. In step P69, for the setting of each imaging position in the z direction, the range of the cervix from the cervical start point znecks to the cervical end point znecke may be imaged at a predetermined cervical tomographic image interval. . This is shown on the RL direction scout image of the neck in FIG. 26 (b). As in the case of the lung field in FIG. 40, the imaging region of the cervix may be determined with a margin before and after in the z direction.

In step P70, as shown in FIGS. 41 and 42, the photographing condition (protocol) is displayed.
In step P71, as shown in FIGS. 41 and 42, it is determined whether or not the operator has made corrections. If YES, the process goes to step P72, and if NO, the process goes to P73.

In step P72, as shown in FIGS. 41 and 42, the operator is corrected.
In step P73, as shown in FIGS. 41 and 42, the photographing condition is determined and set.
In step P74, photographing is performed as shown in FIGS.

In Step P75, as shown in FIGS. 41 and 42, tomographic image reconstruction is performed.
In step P76, as shown in FIGS. 41 and 42, tomographic image display is performed.
Steps P70 to P76 described above may be performed in the same manner as steps P46 to P52 shown in FIGS.

In the third embodiment, an embodiment in which the head from the scout image is automatically recognized will be described.
Features on the scout image at the head include the following features as shown in FIGS. 28 (a) and 28 (b). However, usually scout images in the AP direction are not taken with the head.
1． In both the AP direction (y direction, 90 degree direction) scout image and the RL direction (x direction, 0 degree direction) scout image, the circularity is close to 1 with a flattened weak ellipsoid.
2． In both the AP direction and the RL direction, the outline, profile area, and outline of the skeleton all increase monotonically from the top of the head to the center of the head and decrease from the center of the head to the neck as they progress in the z direction.
3． In both the AP direction and the RL direction, the size of the outer shape and the outer shape of the skeleton are almost equal in the entire head. Especially in the upper half of the head, the outer shape and the outer shape of the skeleton are almost equal due to the skull.
Four. Peripheral distribution ends at the top of the head.

  As new image feature amounts, the skeleton rate Sa (z) in the AP direction and the skeleton rate Sr (z) in the RL direction are determined as in the following (Equation 37) and (Equation 38).

When the image features on the scout images of the heads 1, 2, 3, and 4 described above are expressed by image feature amounts, FIG. 29 is obtained.
As shown in Fig. 29, the outer shape in the AP direction and the outer shape in the RL direction both rise from the top of the head and increase monotonically up to the center of the head, moving from the center of the head to the lower part of the head. Decreases approximately constant or gradually, and decreases and decreases in the neck.

  Also, as shown in FIG. 29, the profile area similarly rises from the top of the head as it advances in the z direction, increases monotonically to the center of the head, and is substantially constant from the center of the head to the lower part of the head. It decreases gradually and decreases in the neck.

  As shown in FIG. 29, the circularity of the outer shape is almost constant or flattened vertically in the center of the head from the top of the head to the center of the head and further down to the neck as it advances in the z direction. Sometimes it becomes.

  In addition, as shown in FIG. 29, the skeletal ratio in the AP direction and the RL direction is about 1 from the top of the head to the center of the head and about 1 or a little from the center of the head to the bottom of the head as it goes in the z direction. It is. When entering the neck, the skeletal ratio in the AP and RL directions decreases.

  Also, as shown in FIG. 29, the AP outline of the skeleton and the RL outline of the skeleton both rise from the top of the head as they progress in the z direction, and increase monotonically up to the center of the head. It decreases almost constant or gradually from the center of the head to the lower part of the head, and decreases and decreases in the neck.

  Also, as shown in FIG. 29, the profile area of the skeleton similarly rises from the top of the head as it progresses in the z direction, monotonically increases to the center of the head, and almost from the center of the head to the lower part of the head. Decreases constantly or gradually, and decreases and decreases in the neck.

Based on these changes in image characteristics, the flow of setting and photographing the head based on the scout image of the head is as shown in FIGS.
In this embodiment, the scout image of the head is generally written only in the RL direction.

In step P81, as shown in FIGS. 44 and 45, scout image projection data collection in the 90-degree direction is performed.
In Step P82, as shown in FIGS. 44 and 45, image reconstruction of a 90-degree scout image is performed.
In step P81 and step P82, scout image projection data collection and image reconstruction in the 90-degree direction are performed in the same manner as in steps P31 and P32 in FIGS.

  In step P83, as shown in FIG. 44 and FIG. 45, binarization is performed with a threshold value Th1 that indicates the outer shape of the body, and a binary peripheral distribution Lr1 (z) in the y direction is measured. In Step P83, the scout image in the RL direction is binarized by the threshold value Th1 that indicates the external shape of the body of the subject, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is The outer shape is Lr1 (z). Note that the method of measuring the binary peripheral distribution is as shown in FIG.

  In step P84, as shown in FIGS. 44 and 45, binarization is performed with a threshold Th2 at which bone can be detected, and a binary peripheral distribution Lr2 (z) in the y direction is measured. In Step P84, the scout image in the RL direction is binarized with a threshold Th2 that indicates the outline of the skeleton or bone of the subject, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is RL The bone outline Lr2 (z) in the direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

  In Step P85, as shown in FIGS. 44 and 45, the density peripheral distribution (profile area) Pa (z) of the scout image is measured. In Step P85, the profile area Pr (z) can be obtained by measuring the peripheral density distribution in the y direction of the scout image in the RL direction.

  Usually, if the subject exists in the center of the tomographic imaging field, that is, near the rotation center of the X-ray data acquisition system, Pr (z) can be obtained almost correctly. However, if the subject approaches the direction of the X-ray tube 21 or approaches the direction of the multi-row X-ray detector 24, the profile area Pr (z) may include a large error.

  In step P86, as shown in FIG. 44 and FIG. 45, from the scout image gr (y, z) and the binary image br2 (y, z) binarized with the threshold value Th2 that can detect the bone, The profile area Pb (z) is measured. In Step P86, the method for obtaining the profile area of the skeleton or the bone part is as (Equation 29).

In Step P87, as shown in FIG. 44 and FIG.
Falling Lr1s, rising Lr1e, outer shape Lr1 (z) in the RL direction,
Falling Pas, rising Pae of profile area Pa (z),
Falling Lr2s, rising Lr2e of external shape Lr2 (z) in the RL direction of the skeleton
Falling Pbs, rising Pbe of skeleton profile area Pb (z),
Measure. In Step P87, the head start point zheads and the head end point zheade, which are the top of the head, are obtained from these change points in the z direction. To determine the start point zheads and end point zheade, you can use some of the above change points, or you can use the average of all of these change points, or these change points. It is also possible to determine by using all the weighted addition values of these, or by using the weighted addition values of some of these change points.

  In Step P88, as shown in FIG. 44 and FIG. 45, alignment of imaging conditions (protocols) registered in advance at the position of the head is performed. In step P88, regarding the setting of each shooting position in the z direction, the head shooting area is set after knowing in advance the range of the head from the head start point zheads to the head end point zheade. Usually, as shown in FIG. 28 (b), the imaging region of the head is often set in a portion above the ear and the eye in parallel with the OM line (a line connecting the ear and the eye). In the embodiment, such a case will be described. A region between k1 (zheads−zheade) in the z direction from the top of the head is set as the imaging region of the head by a coefficient k1 statistically determined in advance from the age, sex, weight, and height of the subject. Similarly, the inclination of the OM line is set based on the inclination θ1 statistically determined from the age, sex, weight, and height of the subject.

In step P89, as shown in FIGS. 44 and 45, the photographing condition (protocol) is displayed.
In step P90, as shown in FIGS. 44 and 45, it is determined whether or not the operator has made corrections. If YES, the process goes to step P91. If NO, the process goes to P92.

In step P91, as shown in FIGS. 44 and 45, the operator is corrected.
In Step P92, as shown in FIGS. 44 and 45, the photographing condition is determined and set.
In step P93, photographing is performed as shown in FIGS.

In Step P94, as shown in FIGS. 44 and 45, tomographic image reconstruction is performed.
In Step P95, as shown in FIGS. 44 and 45, tomographic image display is performed.
Steps P89 to P95 described above may be performed in the same manner as steps P46 to P52 shown in FIGS.

In the fourth embodiment, an embodiment in which the abdomen is automatically recognized from the scout image will be described.
As features on the scout image in the abdomen, as shown in FIG. 30 (a) and FIG. 30 (b), the outline of the scout image has the following features.
1． In both the AP direction (y direction, 90 degree direction) scout image and the RL direction (x direction, 0 degree direction) scout image, the AP direction, RL direction outline, and profile area as it advances from the lung field to the z direction. Will grow. It is about the same size on the waist.
2． The outer shape of the skeleton or bone part in the AP direction, the outer shape of the skeleton or bone part in the RL direction, and the profile area of the skeleton or bone part are somewhat smaller from the lung field and are almost constant. When entering the waist, the outline of the skeleton or bone part in the AP direction, the outer shape of the skeleton or bone part in the RL direction, and the profile area of the skeleton or bone part increase.
3． In both the AP direction and the RL direction, the skeletal rate decreases suddenly from the lung field, remains small in the abdomen, and increases when entering the waist.

FIG. 31 shows the image features on the abdominal scout images 1, 2, and 3 described above as image feature amounts.
As shown in FIG. 31, the outer shape in the AP direction and the outer shape in the RL direction both keep the same size in the abdomen and the same size in the waist as they progress in the z direction. Or, depending on the subject, the abdomen takes a slightly large value and may have a maximum value.

  Further, as shown in FIG. 31, as the profile area similarly advances in the z direction, the same size as the lung field is maintained in the abdomen, and the same size is maintained in the waist. Or, depending on the subject, the abdomen takes a slightly large value and may have a maximum value.

  Further, as shown in FIG. 31, as the circularity of the outer shape progresses in the z direction, the circularity that is flat in the x direction and smaller than 1 is maintained in the abdomen as well as the lung field, and the same size is maintained in the waist. Or, depending on the subject, the abdomen takes a slightly larger value and may be close to 1 or may exceed 1 in some cases.

  In addition, as shown in FIG. 31, the skeletal ratio in the AP direction and the RL direction is a value close to 1 in the lung field as it progresses in the z direction, but becomes a value smaller than 1 in the abdomen, and again in the lumbar region. It approaches a value close to 1.

  In addition, the outline of the skeleton in the AP direction and the outline of the skeleton in the RL direction are close to 1 in the lung field, but smaller than 1 in the abdomen, and again to 1 in the waist. Approaching a close value.

Similarly, as the skeletal profile area advances in the z direction, it is close to 1 in the lung field, but smaller than 1 in the abdomen, and approaches 1 again in the waist.
Based on these image feature amount changes, the abdominal imaging condition setting / imaging flow based on the abdominal scout image is as shown in FIGS.

In Step P101, as shown in FIGS. 46 and 47, scout image projection data is collected in the 0 degree direction and the 90 degree direction.
In Step P102, as shown in FIGS. 46 and 47, image reconstruction of scout images in the 0 degree direction and the 90 degree direction is performed.

In Step P101 and Step P102, scout image projection data collection and image reconstruction in the 0 degree direction and 90 degree direction are performed in the same manner as in Steps P31 and P32 of FIGS.
In step P103, as shown in FIGS. 46 and 47, binarization is performed with a threshold value Th1 indicating the outer shape of the body, and binary peripheral distributions La1 (z) and Lr1 (z) in the x and y directions are measured.

  In step P103, binarization is performed with a threshold value Th1 that indicates the outer shape of the body, and then the outer shape La1 in the AP direction (z) indicates the size of the outer shape in the AP direction as in (Equation 22) and (Equation 23). ) Measure the outer shape Lr1 (z) in the RL direction, which indicates the size of the outer shape in the RL direction. This measurement can be performed by measuring a binary marginal distribution. In step P103, the scout image in the AP direction that was reconstructed with the threshold Th1 that shows the external shape of the body of the subject was binarized, and the binary peripheral distribution in the x direction was measured using the binarized binary image Is the outer shape La1 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the outer shape Lr1 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In step P104, as shown in FIGS. 46 and 47, binarization is performed with a threshold Th2 that can detect a bone, and binary peripheral distributions La2 (z) and Lr2 (z) in the x and y directions are measured.
In step P104, after binarization is performed with a threshold Th2 that indicates the outline of the skeleton or bone, as shown in (Equation 24) and (Equation 25), the skeleton or bone that indicates the size of the bone in the AP direction is shown. The outer shape La2 (z) in the AP direction of the bone part and the outer shape Lr2 (z) in the RL direction of the skeleton or the bone part indicating the size of the outer shape of the bone in the RL direction are measured. This can be done by measuring the binary marginal distribution. At Step P104, the scout image in the AP direction that was reconstructed with the threshold Th2 that shows the skeleton or bone outline of the subject is binarized, and the binary peripheral distribution is measured in the x direction using the binarized binary image The result is the bone outline La2 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the bone outline Lr2 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In Step P105, as shown in FIGS. 46 and 47, the density peripheral distribution (profile area) Pa (z) of the scout image is measured.
In Step P105, the profile area Pa (z) can be obtained by measuring the peripheral density distribution in the x direction of the scout image in the AP direction. Further, the profile area Pr (z) can be obtained by measuring the peripheral density distribution in the y direction of the scout image in the RL direction.

  As in step P65, usually, if the subject exists in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system, Pa (z) and Pr (z) are almost equal. Will be equal. If the scout image has only one of the AP direction and the RL direction, it is sufficient to obtain either one as the profile area Pa (z). If scout images in two directions, AP direction and RL direction, are obtained, the average of the two profile areas Pa (z) and Pr (z) should be calculated and used as the profile area Pa (z). Can do. In this case, a more accurate profile area Pa (z) can be obtained.

In step P106, as shown in FIG. 46 and FIG. 47, the external circularity C (z) is measured from the binary peripheral distributions La1 (z) and Lr1 (z).
As shown in (Equation 38), the external circularity C (z) in step P106 can be obtained from the external shape La1 (z) of the body in the AP direction and the external shape Lr1 (z) of the body in the RL direction.

  In step P107, as shown in FIGS. 46 and 47, a binary image ba2 (x, z) binarized with a threshold value Th2 that can detect a scout image ga (x, z), gr (y, z) and a bone , Br2 (y, z), skeleton or bone profile area Pb (z) is measured.

  The method of obtaining the profile area Pb (z) of the skeleton or the bone part in Step P107 is as (Formula 28) and (Formula 29). If there is only one of the scout images in the AP direction or the RL direction, the profile area Pb (z) of the skeleton or the bone part is obtained according to (Equation 28) if only the AP direction. If only the RL direction is used, it is sufficient to obtain the profile area Pb (z) of the skeleton or the bone part by (Equation 29). If scout images in both the AP direction and the RL direction exist, the AP is usually used if the subject is in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system. Both the skeleton or bone profile area Pb (z) in the direction and the RL direction skeleton or bone profile area Pb (z) should be approximately equal. If scout images in two directions, AP direction and RL direction, are obtained, the average of two Pb (z) can be obtained and used as the profile area Pb (z) of the skeleton or bone. A more accurate one can be obtained.

  In Step P108, as shown in FIGS. 46 and 47, the skeleton ratio Sa (z) in the AP direction, the binary peripheral distributions Lr2 (z), Lr1 (from the binary peripheral distributions La2 (z) and La1 (z) From z), the skeleton ratio Sr (z) in the RL direction is measured.

  As shown in (Formula 37) and (Formula 38), the skeletal ratio Sr (z) in Step P108 is La2 (x2) indicating the external shape of the bone in the AP direction with respect to La1 (x) indicating the external shape of the body in the AP direction. ) Is the skeletal rate Sa (z) in the AP direction, and the ratio of Lr2 (x) indicating the bone shape in the RL direction to the Lr1 (x) indicating the body shape in the RL direction is the skeleton rate Sr ( z).

In Step P109, as shown in FIGS. 46 and 47,
Under conditions where the profile area Pa (z) and the circularity C (z) are within a certain range,
Falling La2s, rising La2e of external shape La2 (z) in the AP direction of the skeleton,
Falling Lr2s, rising Lr2e of external shape Lr2 (z) in the RL direction of the skeleton
Falling Pbs, rising Pbe of skeleton profile area Pb (z),
Falling Sas, rising Sae of AP direction skeleton rate Sa (z),
Measure the falling Srs and rising Sre of the skeletal ratio Sr (z) in the AP direction.

  In step P109, an abdomen start point zabds and an abdomen end point zabde in the z direction are obtained from these change points. In order to determine the start point zabds and end point zabde, it can be determined using some of these change points, or can be determined using the average value of all of these change points. It can also be determined using all the weighted addition values of the change points, or can be determined using some weighted addition values of these change points. An example of an embodiment in which this change point is obtained by an average value is shown in the flowcharts of FIGS. However, the lower limit value of the threshold value of the profile area Pa (z) is Pamin, the upper limit value of the threshold value is Pamax, the lower limit value of the outer circularity C (z) is Cmin, and the upper limit value of the threshold value is Cmax.

In step A1, ss = 0, se = 0, and c = 0 are performed as shown in FIGS.
In step A2, as shown in FIG. 48 and FIG. 49,
Pamin ≦ Pa (La2s) ≦ Pamax and
Cmin ≦ C (La2s) ≦ Cmax and
Pamin ≦ Pa (La2e) ≦ Pamax and
It is determined whether Cmin ≦ C (La2e) ≦ Cmax. If YES, go to step A3, and if NO, go to step A4.

In step A3, as shown in FIGS. 48 and 49, ss = ss + La2s, se = se + La2e, and c = c + 1 are performed.
If it is not within the proper range, it is not subject to averaging.

In step A4, as shown in FIGS. 48 and 49,
Pamin ≦ Pa (Lr2s) ≦ Pamax and
Cmin ≦ C (Lr2s) ≦ Cmax and
Pamin ≦ Pa (Lr2e) ≦ Pamax and
It is determined whether Cmin ≦ C (Lr2e) ≦ Cmax. If YES, go to step A5, and if NO, go to step A6.

In step A5, as shown in FIGS. 48 and 49, ss = ss + Lr2s, se = se + Lr2e, and c = c + 1 are performed.
If it is not within the proper range, it is not subject to averaging.

In step A6, as shown in FIGS. 48 and 49,
Pamin ≦ Pa (Pbs) ≦ Pamax and
Cmin ≦ C (Pbs) ≦ Cmax and
Pamin ≦ Pa (Pbe) ≦ Pamax and
It is determined whether Cmin ≦ C (Pbe) ≦ Cmax. If YES, go to step A7, and if NO, go to step A8.

In step A7, as shown in FIGS. 48 and 49, ss = ss + Pbs, se = se + Pbe, and c = c + 1 are performed.
If it is not within the proper range, it is not subject to averaging.

In step A8, as shown in FIGS. 48 and 49,
Pamin ≦ Pa (Sas) ≦ Pamax and
Cmin ≦ C (Sas) ≦ Cmax and
Pamin ≦ Pa (Sae) ≦ Pamax and
It is determined whether Cmin ≦ C (Sae) ≦ Cmax. If YES, go to step A9, and if NO, go to step A10.

In step A9, as shown in FIGS. 48 and 49, ss = ss + Sas, se = se + Sae, and c = c + 1 are performed.
If it is not within the proper range, it is not subject to averaging.

In step A10, as shown in FIGS. 48 and 49,
Pamin ≦ Pa (Srs) ≦ Pamax and
Cmin ≦ C (Srs) ≦ Cmax and
Pamin ≦ Pa (Sre) ≦ Pamax and
It is determined whether Cmin ≦ C (Sre) ≦ Cmax. If YES, go to step A11, and if NO, go to step A12.

In step A11, as shown in FIGS. 48 and 49, ss = ss + Srs, se = se + Sre, and c = c + 1 are performed.
If it is not within the proper range, it is not subject to averaging.

In step A12, as shown in FIGS. 48 and 49, ss = ss / c and se = se / c are performed.
In step A13, as shown in FIGS. 48 and 49, the change points are ss and se, and zabds = ss and zabde = se.

In this way, the abdomen start point zabds and the abdomen end point zabde can be obtained.
In step P110, as shown in FIGS. 46 and 47, the imaging conditions (protocols) registered in advance at the position of the abdomen are aligned.

  In step P110, each imaging position in the z direction may be set by imaging the abdominal range from the abdominal start point zabds to the abdomen end point zabde at a predetermined abdominal tomographic image interval. This is shown on the AP direction scout image of the abdomen in FIG. 30 (b). As in the case of the lung field in FIG. 40, an abdominal imaging region may be determined with a margin before and after in the z direction.

In step P111, as shown in FIGS. 46 and 47, the photographing condition (protocol) is displayed.
In step P112, as shown in FIGS. 46 and 47, it is determined whether or not the operator has corrected. If YES, the process goes to step P113, and if NO, the process goes to P114.

In step P113, as shown in FIGS. 46 and 47, the operator is corrected.
In step P114, as shown in FIGS. 46 and 47, the photographing condition is determined and set.
In step P115, photographing is performed as shown in FIGS.

In Step P116, as shown in FIGS. 46 and 47, tomographic image reconstruction is performed.
In Step P117, as shown in FIGS. 46 and 47, tomographic image display is performed.
The above steps P111 to P117 may be performed in the same manner as steps P46 to P52 shown in FIGS.

In the fifth embodiment, an embodiment in which the waist is automatically recognized from the scout image will be described.
The features of the scout image at the waist include the following features as shown in the outline of the scout image in FIGS. 32 (a) and 32 (b).
1． In both the AP direction (y direction, 90 degree direction) scout image and the RL direction (x direction, 0 degree direction) scout image, the AP direction, RL outline, and profile area increase as the abdomen progresses in the z direction. It remains. When it moves to the thigh of the lower limb, it gradually decreases.
2． The outer shape of the skeleton or bone part in the AP direction, the outer shape of the skeleton or bone part in the RL direction, and the profile area of the skeleton or bone part increase as they progress from the abdomen to the z direction. When it moves to the thigh of the lower limb, it gradually decreases. In particular, since there are large bones such as sacrum in the lumbar region, the outline of the skeleton or bone part in the AP direction, the outline of the skeleton or bone part in the RL direction, and the profile area of the skeleton or bone part are large.
3． The circularity of the waist is generally closer to an ellipse than the abdomen, and closer to the ellipse when entering the lower limbs. .
Four. Consider the change in the number of regions included on each tomogram. The number of each region in the cross-sectional image at each z-direction coordinate position is one in the abdomen and waist, but increases to two when entering the lower limbs.

When the image features on the above-mentioned 1, 2, 3, and 4 scout images of the waist are expressed by image feature amounts, they are as shown in FIGS.
As shown in FIGS. 33 and 34, both the outer shape in the AP direction and the outer shape in the RL direction are gradually reduced as they enter the lower limbs while maintaining the same size as the abdomen in the waist as they progress in the z direction. .
Also, as shown in FIGS. 33 and 34, the profile area similarly keeps the same size as the abdomen as it advances in the z direction, but gradually becomes smaller as it enters the lower limbs.

Further, as shown in FIGS. 33 and 34, the circularity of the outer shape becomes smaller as it progresses in the z direction to become an ellipse gradually spreading in the RL direction than in the abdomen, and becomes smaller when entering the lower limbs.
Also, as shown in FIGS. 33 and 34, the number of regions included in each tomographic image is 1 in the waist as in the abdomen as it advances in the z direction, but when entering the lower limbs, the number of regions is 2

Further, as shown in FIGS. 33 and 34, the skeleton ratio in the AP direction and the RL direction becomes larger than the abdominal part as it advances in the z direction, and becomes smaller when entering the lower limb part.
Also, as shown in FIGS. 33 and 34, the outline of the skeleton or bone part in the AP direction and the outline of the skeleton or bone part in the RL direction increase as the amount of the skeleton or bone part increases in the z direction. Shows a large value. Smaller when entering the lower limbs.

Further, as shown in FIGS. 33 and 34, the profile area of the skeleton or bone part becomes larger than the abdominal part as it advances in the z direction, and becomes smaller when entering the lower limb part.
Based on these changes in the image feature amount, the waist imaging condition setting / imaging flow based on the waist scout image is as shown in FIGS.

In step P121, as shown in FIGS. 50 and 51, scout image projection data is collected in the 0 degree direction and the 90 degree direction.
In step P122, as shown in FIGS. 50 and 51, image reconstruction of scout images in the 0 degree direction and the 90 degree direction is performed.

In step P121 and step P122, scout image projection data collection and image reconstruction in the 0 degree direction and 90 degree direction are performed in the same manner as in steps P31 and P32 in FIGS.
In step P123, as shown in FIG. 50 and FIG. 51, binarization is performed with a threshold value Th1 that indicates the outer shape of the body, and binary peripheral distributions La1 (z) and Lr1 (z) in the x and y directions are measured.

  In step P123, after binarization is performed with a threshold Th1 that indicates the outer shape of the body, as shown in (Equation 22) and (Equation 23), the outer shape La1 in the AP direction (z ) Measure the outer shape Lr1 (z) in the RL direction, which indicates the size of the outer shape in the RL direction. This measurement can be performed by measuring a binary marginal distribution. In step P123, the scout image in the AP direction that was reconstructed with the threshold Th1 that shows the external shape of the subject's body was binarized, and the result of measuring the binary peripheral distribution in the x direction with the binarized binary image Is the outer shape La1 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the outer shape Lr1 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In step P124, as shown in FIGS. 50 and 51, binarization is performed with a threshold value Th2 that can detect a bone, and binary peripheral distributions La2 (z) and Lr2 (z) in the x and y directions are measured.
In step P124, after binarization is performed with a threshold Th2 that indicates the outline of the skeleton or bone, the skeleton or bone showing the size of the bone outline in the AP direction as shown in (Formula 24) and (Formula 25) The outer shape La2 (z) in the AP direction of the bone part and the outer shape Lr2 (z) in the RL direction of the skeleton or the bone part indicating the size of the outer shape of the bone in the RL direction are measured. This can be done by measuring the binary marginal distribution. At Step P124, the scout image in the AP direction that was reconstructed with the threshold Th2 that shows the skeleton or bone outline of the subject is binarized, and the binary peripheral distribution is measured in the x direction using the binarized binary image The result is the bone outline La2 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the bone outline Lr2 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In step P125, as shown in FIGS. 50 and 51, the density peripheral distribution (profile area) Pa (z) of the scout image is measured.
In Step P125, the profile area Pa (z) can be obtained by measuring the peripheral density distribution in the x direction of the scout image in the AP direction. Further, the profile area Pr (z) can be obtained by measuring the peripheral density distribution in the y direction of the scout image in the RL direction.

  As in step P65, usually, if the subject exists in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system, Pa (z) and Pr (z) are almost equal. Will be equal. If the scout image has only one of the AP direction and the RL direction, it is sufficient to obtain either one as the profile area Pa (z). If scout images in two directions, AP direction and RL direction, are obtained, the average of the two profile areas Pa (z) and Pr (z) should be calculated and used as the profile area Pa (z). Can do. In this case, a more accurate profile area Pa (z) can be obtained.

In step P126, as shown in FIGS. 50 and 51, the outer circularity C (z) is measured from the binary peripheral distributions La1 (z) and Lr1 (z).
The external circularity C (z) in step P126 can be obtained from the external shape La1 (z) of the body in the AP direction and the external shape Lr1 (z) of the body in the RL direction, as shown in (Formula 38).

  In step P127, as shown in FIGS. 50 and 51, a binary image ba2 (x, z) binarized with a threshold value Th2 that can detect a scout image ga (x, z), gr (y, z) and a bone , Br2 (y, z), skeleton or bone profile area Pb (z) is measured.

  The method of obtaining the profile area Pb (z) of the skeleton or the bone part in Step P127 is as (Formula 28) and (Formula 29). If there is only one of the scout images in the AP direction or the RL direction, the profile area Pb (z) of the skeleton or the bone part is obtained according to (Equation 28) if only the AP direction. If only the RL direction is used, it is sufficient to obtain the profile area Pb (z) of the skeleton or the bone part by (Equation 29). If scout images in both the AP direction and the RL direction exist, the AP is usually used if the subject is in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system. Both the skeleton or bone profile area Pb (z) in the direction and the RL direction skeleton or bone profile area Pb (z) should be approximately equal. If scout images in two directions, AP direction and RL direction, are obtained, the average of two Pb (z) can be obtained and used as the profile area Pb (z) of the skeleton or bone. A more accurate one can be obtained.

  In Step P128, as shown in FIG. 50 and FIG. 51, the skeleton ratio Sa (z) in the AP direction, the binary peripheral distributions Lr2 (z), Lr1 (from the binary peripheral distributions La2 (z) and La1 (z) From z), the skeleton ratio Sr (z) in the RL direction is measured.

As shown in (Formula 37) and (Formula 38), the skeletal ratio Sr (z) in Step P128 is La2 (x2) indicating the external shape of the bone in the AP direction with respect to La1 (x) indicating the external shape of the body in the AP direction. ) Is the skeletal rate Sa (z) in the AP direction, and the ratio of Lr2 (x) indicating the bone shape in the RL direction to the Lr1 (x) indicating the body shape in the RL direction is the skeleton rate Sr ( z).
In Step P129, as shown in FIGS. 50 and 51, the number of regions Lab (z) in the AP direction is measured.

  In Step P129, as the number of areas in the AP direction Lab (z), as shown in FIG. 56, in the outline of the scout image in the AP direction, the number of areas in the x direction at a certain coordinate position in the z direction, that is, the x direction is divided. The number of line segments and the number of continuous line segments are defined as the number of regions in the x direction.

In Step P130, as shown in FIGS. 50 and 51,
Profile area Pa (z), external circularity C (z), AP direction external shape La1 (z), RL direction external shape Lr1 (z), AP direction area number Lab (z) In the original
La2s rising, falling La2e of external shape La2 (z) in the AP direction of the skeleton,
Rr2s rise, fall Lr2e of external shape Lr2 (z) in RL direction of skeleton,
Rise Pbs, Fall Pbe of profile area Pb (z) of skeleton,
Rise Sas, fall Sae of AP direction skeleton rate Sa (z),
Measure rise Srs and fall Sre of skeletal ratio Sr (z) in the AP direction.

  In step P130, a waist start point zhips and a waist end point zhipe in the z direction are obtained from these change points. In order to determine the start point zhips and end point zhipe, you can use some of these change points, or you can use the average of all of these change points, It can also be determined using all the weighted addition values of the change points, or can be determined using some weighted addition values of these change points. An example of an embodiment in which this change point is obtained by an average value is shown in the flowchart of FIG. However, the lower limit of the profile area Pa (z) is Pamin, the upper limit of the threshold is Pamax, the lower limit of the contour circularity C (z) is Cmin, the upper limit of the threshold is Cmax, and the lower limit of the outer shape in the AP direction. The value is La1min, the upper limit is La1max, the lower limit of the outer shape in the RL direction is Lr1min, and the upper limit is Lr1max. Also, the number of areas in the AP direction must be “1”.

In step A21, as shown in FIG. 52, ss = 0, se = 0, C = 0, and k = 0.
In step A22, as shown in FIG.
If k = 0, go to step A23.
If k = 1, go to step A24.
If k = 2, go to step A25.
If k = 3, go to step A26.
If k = 4, go to step A27.

In step A23, as shown in FIG. 52, z1 = La2s and z2 = La2e.
In step A24, as shown in FIG. 52, z1 = Lr2s and z2 = Lr2e.
In step A25, as shown in FIG. 52, z1 = Pbs and z2 = Pbe.

In step A26, as shown in FIG. 52, z1 = Sas and z2 = Sae.
In step A27, as shown in FIG. 52, z1 = Srs and z2 = Sre.
In step A28, as shown in FIG.
Pamin ≦ Pa (z1) ≦ Pamax and
Cmin ≦ C (z1) ≦ Cmax and
La1min ≦ La1 (z1) ≦ La1max and
Lr1min ≦ Lr1 (z1) ≦ Lr1max and
Lab (z1) = 1 and
Pamin ≦ Pa (z2) ≦ Pamax and
Cmin ≦ C (z2) ≦ Cmax and
La1min ≦ La1 (z2) ≦ La1max and
Lr1min ≦ Lr1 (z2) ≦ Lr1max and
It is determined whether Lab (z2) = 1. If YES, go to step A29, and if NO, go to step A30.

In step A29, as shown in FIG. 52, ss = ss + z1, se = se + z2, and c = c + 1 are performed.
That is, when z = La2s and z = La2e,
Or, when z = Lr2s and z = Lr2e,
Or, when z = Pbs and z = Pbe
Or z = Sas, z = Sae,
Or, when z = Srs and z = Sre,
The profile area Pa (z), the circularity C (z), the external shape La1 (z) in the AP direction, the external shape Lr1 (z) in the RL direction, and the number of areas Lab (z) in the AP direction are within the appropriate ranges. After confirming this, the combination of z = La2s and z = La2e, or the combination of z = Lr2s and z = Lr2e, or the combination of z = Pbs and z = Pbe, or z = Sas and z = Sae A combination or a combination of z = Srs and z = Sre is set as an average processing target. If there is something that is not within the proper range, the combination of z = La2s and z = La2e, or the combination of z = Lr2s and z = Lr2e, or the combination of z = Pbs and z = Pbe, or A combination of z = Sas and z = Sae or a combination of z = Srs and z = Sre is not subjected to averaging processing. Such control can be performed.

In step A30, as shown in FIG. 52, it is determined whether k = 4. If YES, the process ends. If NO, go to step A31.
In step A31, as shown in FIG. 52, ss = ss / c and se = se / c are performed.

In step A32, as shown in FIG. 52, the change points are ss and se, and zhips = ss and zhipe = se. Then, the process ends.
In step A33, as shown in FIG. 52, k = k + 1 is performed, and the process returns to step A22.
In this way, the waist start point zhips and the waist end point zhipe can be obtained.

In step P131, as shown in FIG. 52, the imaging conditions (protocols) registered in advance at the waist position are aligned.
In step P131, the setting of each imaging position in the z direction may be performed by imaging the waist region from the waist start point zhips to the waist end point zhipe at a predetermined waist tomographic image interval. This is shown on the AP direction scout image of the waist in FIG. 32 (a). As in the case of the lung field in FIG. 40, the imaging region of the waist may be determined with a margin before and after in the z direction.

In step P132, as shown in FIG. 52, the photographing condition (protocol) is displayed.
In step P133, as shown in FIG. 52, it is determined whether or not the operator has corrected. If YES, the process goes to step P134, and if NO, the process goes to P135.

In Step P134, the operator is corrected as shown in FIG.
In Step P135, as shown in FIG. 52, shooting conditions are determined and set.
In Step P136, photographing is performed as shown in FIG.

In Step P137, as shown in FIG. 52, tomographic image reconstruction is performed.
In step P138, as shown in FIG. 52, tomographic image display is performed.
The above steps P132 to P138 may be performed in the same manner as steps P46 to P52 shown in FIGS.

In the sixth embodiment, an embodiment in which the lower limbs are automatically recognized from the scout image will be described.
As features of the scout image in the lower limb, as shown in FIG. 35 (a) and FIG. 35 (b), the outline of the scout image has the following features.
1． In both the AP direction (y direction, 90 degree direction) scout image and the RL direction (x direction, 0 degree direction) scout image, the AP direction, RL outline, and profile area gradually increase from the waist to the z direction. It ends up getting smaller and finally getting larger at the toe ankle.
2． The outline of the skeleton or bone part in the AP direction, the outline of the skeleton or bone part in the RL direction, and the profile area of the skeleton or bone part are gradually decreased from the lumbar part to the femur as it progresses in the z direction. Moreover, it progresses in the z direction, increases at the knee joint, and decreases again when moving to the tibia and ribs. Furthermore, it progresses to az direction and increases again in an ankle part, and is complete | finished.
3． The number of areas included in the tomographic image is one up to the lower back, but when it advances in the z direction, it increases to two areas in the lower limbs as shown in FIG. 36 (a).
Four. The number of skeletal or bone regions is one in the femur portion of the lower limbs and four in the tibia and rib portions as shown in FIG. 36 (b).

When the image features on the scout images of the lower limbs of 1, 2, 3, and 4 are expressed by image feature amounts, they are as shown in FIGS.
As shown in FIGS. 37 and 38, both the outer shape in the AP direction and the outer shape in the RL direction gradually become smaller as it enters the lower limb as it progresses from the waist to the z direction. Finally, it becomes larger at the ankle joint and the toe and ends.

In addition, as shown in FIGS. 37 and 38, the profile area gradually decreases in the lower limb as it advances in the z direction. Finally, it becomes larger at the ankle joint and the toe and ends.
Also, as shown in FIGS. 37 and 38, as the circularity of the outer shape of the ellipsoid in the x-axis direction progresses in the z-direction, the lower limbs also spread in the x-axis direction with two lower limbs. The circularity proceeds with the smallness, and the circularity increases at the toe portion to finish.

  Further, as shown in FIGS. 37 and 38, the number of regions included in the tomographic image is 1 in the lower back as it advances in the z direction, but the number of regions is 2 when entering the lower limbs. In addition, the number of areas becomes 0 after the foot part.

  In addition, as shown in Figs. 37 and 38, the outline of the skeleton or bone in the AP direction and the outline in the RL direction increased in the pelvis of the lumbar part as it progressed in the z direction, but smaller in the femur of the lower limb part. Become. Further progress in the z direction increases at the knee joint. Further proceed in the z direction and become smaller again at the tibia and ribs. Furthermore, it progresses to az direction, and it increases and complete | finishes in an ankle joint part and a toe part.

  Also, as shown in FIGS. 37 and 38, as the profile area of the skeleton or bone portion similarly advances in the z direction, the larger value in the pelvis of the lumbar portion becomes smaller in the femur of the lower limb portion. Further progress in the z direction increases at the knee joint. Further proceed in the z direction and become smaller again at the tibia and ribs. Furthermore, it progresses to az direction, and it increases and complete | finishes in an ankle joint part and a toe part.

  Based on these changes in image feature amounts, the imaging condition setting / imaging flow of the lower limbs based on the scout image of the lower limbs is as shown in FIGS. In step P141, as shown in FIGS. 53 and 54, scout image projection data is collected in the 0 degree direction and the 90 degree direction.

In Step P142, as shown in FIGS. 53 and 54, image reconstruction of scout images in the 0 degree direction and the 90 degree direction is performed.
In step P141 and step P142, scout image projection data collection and image reconstruction in the 0-degree direction and the 90-degree direction are performed in the same manner as in steps P31 and P32 in FIGS.

In step P143, as shown in FIGS. 53 and 54, binarization is performed with a threshold value Th1 that indicates the outer shape of the body, and binary peripheral distributions La1 (z) and Lr1 (z) in the x and y directions are measured.
In step P143, after binarization is performed with a threshold Th1 that indicates the outer shape of the body, as shown in (Equation 22) and (Equation 23), the outer shape La1 in the AP direction (z ) Measure the outer shape Lr1 (z) in the RL direction, which indicates the size of the outer shape in the RL direction. This measurement can be performed by measuring a binary marginal distribution. In Step P143, the scout image in the AP direction that was reconstructed with the threshold Th1 that shows the external shape of the subject's body was binarized, and the result of measuring the binary peripheral distribution in the x direction with the binarized binary image Is the outer shape La1 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the outer shape Lr1 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In step P144, as shown in FIGS. 53 and 54, binarization is performed with a threshold Th2 at which bone can be detected, and binary peripheral distributions La2 (z) and Lr2 (z) in the x and y directions are measured.
In step P144, after binarization is performed with a threshold Th2 that shows the outline of the skeleton or bone, the skeleton or bone showing the size of the bone outline in the AP direction as shown in (Equation 24) and (Equation 25). The outer shape La2 (z) in the AP direction of the bone part and the outer shape Lr2 (z) in the RL direction of the skeleton or the bone part indicating the size of the outer shape of the bone in the RL direction are measured. This can be done by measuring the binary marginal distribution. In Step P144, the AP direction scout image reconstructed with a threshold value Th2 that shows the skeleton or bone contour of the subject is binarized, and the binary peripheral distribution is measured in the x direction using the binarized binary image. The result is the bone outline La2 (z) in the AP direction. Also, the scout image in the RL direction is binarized, and the result of measuring the binary peripheral distribution in the y direction with the binarized binary image is the bone outline Lr2 (z) in the RL direction. Note that the method of measuring the binary peripheral distribution is as shown in FIG.

In Step P145, as shown in FIGS. 53 and 54, the density peripheral distribution (profile area) Pa (z) of the scout image is measured.
In Step P145, the profile area Pa (z) can be obtained by measuring the peripheral density distribution in the x direction of the scout image in the AP direction. Further, the profile area Pr (z) can be obtained by measuring the peripheral density distribution in the y direction of the scout image in the RL direction.

  As in step P65, usually, if the subject exists in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system, Pa (z) and Pr (z) are almost equal. Will be equal. If the scout image has only one of the AP direction and the RL direction, it is sufficient to obtain either one as the profile area Pa (z). If scout images in two directions, AP direction and RL direction, are obtained, the average of the two profile areas Pa (z) and Pr (z) should be calculated and used as the profile area Pa (z). Can do. In this case, a more accurate profile area Pa (z) can be obtained.

In step P146, as shown in FIGS. 53 and 54, the outer circularity C (z) is measured from the binary peripheral distributions La1 (z) and Lr1 (z).
The external circularity C (z) in step P146 can be obtained from the external shape La1 (z) of the body in the AP direction and the external shape Lr1 (z) of the body in the RL direction, as shown in (Formula 38).

  In step P147, as shown in FIGS. 53 and 54, a binary image ba2 (x, z) binarized with a threshold value Th2 that can detect a scout image ga (x, z), gr (y, z) and a bone , Br2 (y, z), skeleton or bone profile area Pb (z) is measured.

  The method of obtaining the profile area Pb (z) of the skeleton or the bone part in Step P147 is as (Formula 28) and (Formula 29). If there is only one of the scout images in the AP direction or the RL direction, the profile area Pb (z) of the skeleton or the bone part is obtained according to (Equation 28) if only the AP direction. If only the RL direction is used, it is sufficient to obtain the profile area Pb (z) of the skeleton or the bone part by (Equation 29). If scout images in both the AP direction and the RL direction exist, the AP is usually used if the subject is in the center of the tomographic field, that is, near the rotation center of the X-ray data acquisition system. Both the skeleton or bone profile area Pb (z) in the direction and the RL direction skeleton or bone profile area Pb (z) should be approximately equal. If scout images in two directions, AP direction and RL direction, are obtained, the average of two Pb (z) can be obtained and used as the profile area Pb (z) of the skeleton or bone. A more accurate one can be obtained.

  In step P148, as shown in FIGS. 53 and 54, the skeleton ratio Sa (z) in the AP direction, the binary peripheral distributions Lr2 (z), Lr1 (from the binary peripheral distributions La2 (z) and La1 (z) From z), the skeleton ratio Sr (z) in the RL direction is measured.

  As shown in (Formula 37) and (Formula 38), the skeletal ratio Sr (z) in Step P148 is La2 (x) indicating the external shape of the bone in the AP direction with respect to La1 (x) indicating the external shape of the body in the AP direction. ) Is the skeletal rate Sa (z) in the AP direction, and the ratio of Lr2 (x) indicating the bone shape in the RL direction to the Lr1 (x) indicating the body shape in the RL direction is the skeleton rate Sr ( z).

In Step P149, as shown in FIGS. 53 and 54, the number of regions Lab (z) in the AP direction is measured.
In step P149, as shown in FIG. 56 as the number of areas Lab (z) in the AP direction, the number of areas in the x direction at a certain coordinate position in the z direction, that is, a separate line in the x direction, in the outline of the scout image in the AP direction. The number of minutes and the number of continuous line segments are defined as the number of regions in the x direction.

In Step P150, as shown in FIGS.
Under the conditions that the outer shape in the AP direction, the outer shape in the RL direction, the profile area, the circularity of the outer shape, and the number of regions in the AP direction exceed a certain value,
Falling La2s of the outline La2 (z) in the AP direction of the skeleton, end point La2e,
Falling Lr2s of the outer shape Lr2 (z) in the RL direction of the skeleton, end point Lr2e,
Falling Pbs, end point Pbe of skeleton profile area Pb (z),
Falling Sas of skeleton rate Sa (z) in the AP direction, end point Sae,
Measure the falling Srs and end point Sre of the skeletal ratio Sr (z) in the AP direction.

  In Step P150, the start point zlegs of the lower limb part in the z direction and the end point zlege of the lower limb part are obtained from these change points. In order to determine the start point zlegs and the end point zlege, it is possible to determine by using some of these change points, it is also possible to determine by using the average value of all of these change points, It can also be determined using all the weighted addition values of the change points, or can be determined using some weighted addition values of these change points. An example of an embodiment in which this change point is obtained by an average value is shown in the flowchart of FIG. However, the lower limit of the profile area Pa (z) is Pamin, the upper limit of the threshold is Pamax, the lower limit of the contour circularity C (z) is Cmin, the upper limit of the threshold is Cmax, and the lower limit of the outer shape in the AP direction. The value is La1min, the upper limit is La1max, the lower limit of the outer shape in the RL direction is Lr1min, and the upper limit is Lr1max. Also, the number of areas in the AP direction must be “1”.

In step A41, as shown in FIG. 55, ss = 0, se = 0, C = 0, and k = 0.
In step A42, as shown in FIG.
If k = 0, go to step A43.
If k = 1, go to step A44.
If k = 2, go to step A45.
If k = 3, go to step A46.
If k = 4, go to step A47.

In step A43, as shown in FIG. 55, z1 = La2s and z2 = La2e.
In step A44, as shown in FIG. 55, z1 = Lr2s and z2 = Lr2e.
In step A45, as shown in FIG. 55, z1 = Pbs and z2 = Pbe.

In step A46, as shown in FIG. 55, z1 = Sas and z2 = Sae.
In step A47, as shown in FIG. 55, z1 = Srs and z2 = Sre.
In step A48, as shown in FIG.
Pamin ≦ Pa (z1) ≦ Pamax and
Cmin ≦ C (z1) ≦ Cmax and
La1min ≦ La1 (z1) ≦ La1max and
Lr1min ≦ Lr1 (z1) ≦ Lr1max and
Lab (z1) = 1 and
Pamin ≦ Pa (z2) ≦ Pamax and
Cmin ≦ C (z2) ≦ Cmax and
La1min ≦ La1 (z2) ≦ La1max and
Lr1min ≦ Lr1 (z2) ≦ Lr1max and
It is determined whether Lab (z2) = 1. If YES, go to step A49, and if NO, go to step A50.

In step A49, as shown in FIG. 55, ss = ss + z1, se = se + z2, and c = c + 1 are performed.
In step A50, as shown in FIG. 55, it is determined whether k = 4. If YES, the process ends. If NO, go to step A51.

In step A51, as shown in FIG. 55, ss = ss / c and se = se / c are performed.
In step A52, as shown in FIG. 55, the change points are ss and se, and zlegs = ss and zlege = se. Then, the process ends.

In step A53, as shown in FIG. 55, k = k + 1 is performed, and the process returns to step A52.
In this way, the start point zlegs of the lower limbs and the end point zlege of the lower limbs can be obtained.
In step P151, as shown in FIGS. 53 and 54, the imaging conditions (protocols) registered in advance at the positions of the lower limbs are aligned. In step P151, regarding the setting of each imaging position in the z direction, the range of the lower limb from the lower limb start point zlegs to the lower limb end point zlege may be imaged at a predetermined lower limb tomographic image interval. . This is shown on the AP direction scout image of the lower limbs in FIG. 35 (b). As in the case of the lung field in FIG. 40, the imaging region of the lower limbs may be determined with a margin before and after in the z direction.

In step P152, as shown in FIGS. 53 and 54, the photographing condition (protocol) is displayed.
In step P153, as shown in FIG. 53 and FIG. 54, it is determined whether or not the operator has corrected. If YES, the process goes to step P154, and if NO, the process goes to P114.

In Step P154, as shown in FIGS. 53 and 54, the operator is corrected.
In Step P155, as shown in FIGS. 53 and 54, the photographing condition is determined and set.
In step P156, photographing is performed as shown in FIGS.

In Step P157, as shown in FIGS. 53 and 54, tomographic image reconstruction is performed.
In Step P158, as shown in FIGS. 53 and 54, tomographic image display is performed.
Steps P152 to P158 described above may be performed in the same manner as Steps P46 to P52 shown in FIGS.

  In the X-ray CT apparatus 100 described above, according to the X-ray CT apparatus or X-ray CT imaging method of the present invention, a conventional multi-row X-ray detector or a matrix structure typified by a flat panel X-ray detector is used. Conventional scan (X-ray cone beam that spreads in the z direction at the start and end of conventional scan (axial scan) or cine scan or helical scan of X-ray CT system with 2D area X-ray detector ( Axial scan) or cine scan or helical scan exposure reduction.

  In this embodiment, in the recognition of each part and the range and position of imaging conditions (protocols) in each part, the outer shape in the AP direction, the outer shape in the RL direction, the profile area, the outer circularity, the region in the AP direction The number, the outline of the AP direction in the AP direction, the outline of the skeleton in the RL direction, the profile area of the skeleton, the skeleton ratio in the AP direction, the skeleton ratio in the RL direction, etc. are used. The same effect can be obtained by using parts or using other parts.

  The image reconstruction method in this embodiment may be a conventionally known three-dimensional image reconstruction method using the Feldkamp method. Furthermore, other three-dimensional image reconstruction methods may be used. Alternatively, two-dimensional image reconstruction may be used.

  Further, in this embodiment, the case where the X-ray automatic exposure mechanism of the X-ray CT apparatus is not used is described, but the same effect can be obtained when the X-ray automatic exposure mechanism of the X-ray CT apparatus is used. be able to.

  Although the present embodiment describes the case where the scanning gantry 20 is not tilted, the same effect can be obtained even in the case of so-called tilt scanning in which the scanning gantry 20 is tilted.

Although the present embodiment describes a case where X-ray data collection is not synchronized with a biological signal, the same effect can be obtained even when synchronized with a biological signal, particularly a heartbeat signal.
In this embodiment, an X-ray CT apparatus having a two-dimensional X-ray area detector having a matrix structure represented by a multi-row X-ray detector or a flat panel X-ray detector is described. The same effect can be obtained in the X-ray CT apparatus of the row X-ray detector.

  In the present embodiment, the scout scan is realized by moving the cradle 12 of the imaging table 10 in the z direction. However, by moving the scanning gantry 20 or the rotating unit 15 in the scanning gantry 20 relative to the cradle 12 of the imaging table 10, relatively similar effects can be obtained.

  In this embodiment, the coefficient of the column direction (z direction) filter having a different coefficient for each column is superimposed on the column direction of the X-ray projection data preprocessed or beam hardening corrected for each channel. Thus, by adjusting the variation in image quality, the slice thickness is uniform in each column, artifacts are suppressed, and noise-reduced image quality is realized. For this, various z-direction filter coefficients can be considered, and in any case, the same effect can be obtained.

  In the present embodiment, the medical X-ray CT apparatus is described based on the original, but in an industrial X-ray CT apparatus or an X-ray CT-PET apparatus, an X-ray CT-SPECT apparatus combined with other apparatuses, etc. Can also be used.

It is a block diagram which shows the X-ray CT apparatus concerning one Embodiment of this invention. It is explanatory drawing which looked at the X-ray generator (X-ray tube) and the multi-row X-ray detector in the xy plane. It is explanatory drawing which looked at the X-ray generator (X-ray tube) and the multi-row X-ray detector on the yz plane. It is a flowchart which shows the flow of subject imaging | photography. It is a flowchart which shows schematic operation | movement of the image reconstruction of the X-ray CT apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the detail of pre-processing. It is a flowchart which shows the detail of a three-dimensional image reconstruction process. It is a conceptual diagram which shows the state which projects the line on an image reconstruction area | region to a X-ray transmissive direction. It is a conceptual diagram which shows the line projected on the X-ray detector surface. It is a conceptual diagram which shows the state which projected the projection data Dr (view, x, y) on the image reconstruction area. It is a conceptual diagram which shows the backprojection pixel data D2 of each pixel on an image reconstruction area. It is explanatory drawing which shows the state which obtains backprojection data D3 by adding all the views to backprojection pixel data D2 corresponding to a pixel. It is a conceptual diagram which shows the state which projects the line on a circular image reconstruction area | region to a X-ray transmissive direction. It is a figure which shows the imaging condition input screen of an X-ray CT apparatus. It is a figure which shows the example of the volume rendering 3D image display method, the MPR image display method, and the 3D MIP image display method. It is a flowchart of the flow of a process of a present Example. FIG. 6 is a flowchart of a determination example 1 for each part from a scout image. FIG. 10 is a flowchart of a determination example 2 for each part from a scout image. (A) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of a lung field part. (B) It is a figure which shows the scout image of the RL direction (x-axis direction, 90 degree direction) of a lung field part. It is a figure which shows the change of each image feature-value in a lung field part. It is a flowchart of the imaging condition setting of the imaging | photography site | part by a scout image, and the flow of an imaging process. It is a flowchart of the imaging condition setting of the imaging | photography site | part by a scout image, and the flow of an imaging process. It is a flowchart of the flow of the image noise removal process by a logic filter. It is a figure which shows the density | concentration peripheral distribution and binary peripheral distribution of a scout image. (a) It is a figure which shows a ferret diameter. (b) It is a figure which shows circularity. (c) A diagram showing a light and shade sum D. FIG. (d) It is a figure which shows area ratio SR = S / (lx * ly). (A) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of a neck. (B) It is a figure which shows the scout image of RL direction (x-axis direction, 90 degree direction) of a neck. It is a figure which shows the change of each image feature-value in a neck part. (A) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of a head. (B) It is a figure which shows the scout image of the RL direction (x-axis direction, 90 degree direction) of a head. It is a figure which shows the change of each image feature-value in a head. (A) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of an abdominal part. (B) It is a figure which shows the scout image of RL direction (x-axis direction, 90 degree direction) of an abdominal part. It is a figure which shows the change of each image feature-value in an abdominal part. (A) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of a waist | hip | lumbar part. (B) It is a figure which shows the scout image of the RL direction (x-axis direction, 90 degree direction) of a waist | hip | lumbar part. It is a figure which shows the change of each image feature-value in a waist | hip | lumbar part. It is a figure which shows the change of each image feature-value in a waist | hip | lumbar part. (a) It is a figure which shows the scout image of AP direction (y-axis direction, 0 degree direction) of a leg part. (b) It is a figure which shows the scout image of the RL direction (x-axis direction, 90 degree direction) of a leg part. (a) It is a figure which shows two area | regions in the tomogram of the femur part of a leg part. (b) It is a figure which shows four bone part area | regions in the tomogram of the tibia and rib part of a leg part. It is a figure which shows the change of each image feature-value in a leg part. It is a figure which shows the change of each image feature-value in a leg part. It is a figure which shows the binarization process in a lung field part, and a region numbering process. It is a figure which shows the imaging conditions set to the lung field part. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the neck by a scout image. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the neck by a scout image. It is a figure which shows the user interface of the imaging condition display of each candidate. It is a flowchart of the imaging | photography condition setting of the head by a scout image, and the flow of imaging | photography. It is a flowchart of the imaging | photography condition setting of the head by a scout image, and the flow of imaging | photography. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the abdomen by a scout image. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the abdomen by a scout image. It is a flowchart of the flow of the average process of the change point in an abdomen. It is a flowchart of the flow of the average process of the change point in an abdomen. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the waist | lumbar part by a scout image. It is a flowchart of the flow of the imaging condition setting and imaging | photography of the waist | lumbar part by a scout image. It is a flowchart of the flow of the average process of the change point in a waist | hip | lumbar part. It is a flowchart of the imaging condition setting and imaging | photography flow of a lower limb part by a scout image. It is a flowchart of the imaging condition setting and imaging | photography flow of a lower limb part by a scout image. It is a flowchart of the flow of the average process of the change point in a leg part. It is a figure which shows the number of area | region Lab (z) of AP direction of each site | part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation console 2 Input device 3 Central processing unit 5 Data collection buffer 6 Monitor 7 Storage device 10 Imaging table 12 Cradle 15 Rotating part 20 Scanning gantry 21 X-ray tube 22 X-ray controller 23 Collimator 24 Multi-row X-ray detector or two-dimensional X-ray area detector 25 Data acquisition device (DAS)
26 Rotation unit controller 27 Scanning gantry tilt controller 28 Beam forming X-ray filter 29 Control controller 30 Slip ring dP X-ray detector plane P Image reconstruction area PP Projection plane
IC rotation center (ISO)
CB X-ray beam
BC beam center axis
D Multi-row X-ray detector width on the rotation axis

Claims (6)

Collecting X-ray projection data transmitted through the subject while rotating the X-ray generator and the X-ray detector that detects X-rays relative to each other around the center of rotation. X-ray projection data that is transmitted while the scan mode or X-ray detector that detects X-rays relative to the X-ray generator is fixed at a certain rotation angle and the subject in between is moved in the direction of the body axis X-ray data acquisition means with both data acquisition modes of the scout mode
Image reconstruction means for reconstructing an image of the projection data collected from the X-ray data collection means;
Image display means for displaying a tomographic image reconstructed by the image reconstruction means;
In an X-ray CT apparatus equipped with imaging condition setting means for setting various imaging conditions,
The imaging condition setting means is configured to automatically generate a scout image of the subject imaged using the scout mode based on respective determination criteria for identifying each part in a plurality of predetermined parts included in the subject. Analyzing each part contained in the subject and specifying the position thereof, and a protocol set for the part based on the positional information of the imaging and the relationship between the part and the protocol stored in advance. An X-ray CT apparatus comprising: protocol presenting means for presenting protocol candidates other than imaging position information suitable for an automatically extracted part. The X-ray CT apparatus according to claim 1, wherein the protocol other than the imaging position information includes at least one of the number of images, an image interval, a slice thickness, a tube voltage, and a tube current. The X-ray CT apparatus according to claim 1, wherein the plurality of parts include any one of a lumbar part, a lung field part, a lower limb part, a neck part, an abdomen part, and a head part. 4. The apparatus according to claim 1, wherein the part specifying unit classifies the plurality of parts by using a skeleton ratio that is a ratio of outer shapes in the scout image photographed from two orthogonal directions. 5. X-ray CT apparatus according to item. 5. The device according to claim 1, wherein the part specifying unit classifies the plurality of parts using a profile area of a projection data profile in the scout image photographed from two orthogonal directions. X-ray CT apparatus described in 1. The said site | part specifying means specifies a site | part using the said scout image which performed the binarization process by a predetermined threshold value, The Claim 1 characterized by the above-mentioned. X-ray CT system.