CT apparatus, operation method of CT apparatus, and operation program of CT apparatus

Abstract

To output projection data including an entire subject even when an output data amount of the projection data to be output to a console is reduced.SOLUTION: The CT apparatus 11 sets the subject region in the imaging range of the radiographic image using the information on the subject, calculates the size of the peripheral region in the range outside the subject region, which is the region around the subject region and in which the subject is estimated to protrude from the subject region due to body movement, as the degree of margin with respect to the subject region before the main imaging of the subject, and outputs the projection data of the channel corresponding to the range of the enlarged subject region obtained by adding the peripheral region to the subject region to the console 17 in the main imaging of the subject.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a CT device, an operating method for a CT device, and an operating program for a CT device. [Background technology]

[0002] Patent Document 1 describes an X-ray diagnostic device that calculates a subject data ratio indicating the proportion of data areas where X-rays have passed through the subject for multiple slice rows and front scan image data and side scan image data of a subject captured with an X-ray detector, calculates a view rate based on the subject data ratio, determines data areas where X-rays have not passed through the subject from projection data of the subject captured based on the view rate, and encodes the projection data with the data areas removed into transmission data.

[0003] Patent document 2 describes a medical image diagnostic device that collects detection data having a first resolution related to a subject, and outputs, from the collected detection data, first detection data that corresponds to a first region of the subject and has the first resolution, and second detection data that corresponds to a second region of the subject and has a second resolution lower than the first resolution, in association with detection region information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-22427 [Patent Document 2] Japanese Patent Publication No. 2022-26909 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in a photon-counting CT apparatus, as the number of photoelectric conversion elements in the radiation detector increases, the output time for outputting projection data from the radiation detector to the console tends to become longer.

[0006] Therefore, rather than outputting the entire projection data to the console, the amount of output data can be reduced by outputting only the projection data corresponding to the subject area and a predetermined range of peripheral areas extending outward from the subject area to the console.

[0007] On the other hand, the range of the subject area is set based on a scanogram image of the subject taken before the actual scan in order to determine the range of the subject to be photographed by CT, but the position of the subject during the actual scan may change from the position at the time of the scanogram image. For this reason, projection data of the area surrounding the subject area is also output to the console in addition to the subject area, but the amount of body movement varies depending on the part of the subject.

[0008] Therefore, if the range of the peripheral region is fixed to a predetermined range, a situation may arise in which part of the subject is not included in the projection data output to the console.

[0009] The technology disclosed herein provides a CT device, an operating method for a CT device, and an operating program for a CT device that can output projection data including the entire subject even when the amount of projection data output to a console is reduced. [Means for solving the problem]

[0010] The CT device according to the technology of the present disclosure includes a processor, which uses information about the subject to set a subject area within the imaging range of a radiographic image, and before the actual imaging of the subject, calculates the size of a peripheral area surrounding the subject area, outside the subject area where it is estimated that the subject will protrude from the subject area due to body movement, as a margin degree for the subject area, and during the actual imaging of the subject, outputs to a console projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area.

[0011] The processor preferably calculates the margin level depending on the part of the subject being photographed.

[0012] It is preferable that the processor calculates the margin level according to the attributes of the person who is the subject.

[0013] Preferably, the processor estimates the attributes of the object from an optical image of the object.

[0014] It is preferable that the processor resets the display range of the subject area, which has been set in advance, in accordance with an instruction from an operator before actual photography of the subject.

[0015] The processor preferably sets the object region based on a tomographic model of the object generated using pre-generation data used to generate the scanogram image, or on an optical image of the object.

[0016] It is preferable that the processor calculates the margin degree for each shooting direction of the subject, and during the actual shooting of the subject, outputs to the console the projection data of the channel corresponding to the range of the subject area to which the peripheral area represented by the margin degree has been added.

[0017] The processor preferably outputs to the console projection data including a channel corresponding to the range of the enlarged object region as well as a specific channel that the console references to reconstruct a tomographic image of the object.

[0018] The processor preferably controls a radiation field limiter that limits the radiation field so as not to irradiate outside the enlarged subject area.

[0019] It is preferable that the processor adjusts the display range of the tomographic image of the subject reconstructed from the projection data in accordance with the number of channels included in the projection data received by the console, and displays the tomographic image of the subject with the adjusted display range on the display device.

[0020] The processor preferably readjusts the display range, which has been adjusted in accordance with the number of channels included in the projection data, in accordance with an instruction from the operator.

[0021] The processor preferably sets pixel values ​​of pixels in a range corresponding to an area outside the enlarged object area in the tomographic image of the object to a predetermined value.

[0022] The operating program of the CT device according to the technology of the present disclosure is a program that causes a computer to execute a process of setting a subject area in the imaging range of a radiographic image using information about the subject, calculating the size of a peripheral area in the area surrounding the subject area, outside the subject area where the subject is estimated to protrude from the subject area due to body movement, as a margin degree for the subject area, and outputting, to a console, projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area, before the actual imaging of the subject.

[0023] The operating method of a CT device according to the technology of the present disclosure is a method in which a computer is caused to execute a process in which a subject area is set in the imaging range of a radiographic image using information about the subject, and before the actual imaging of the subject, the size of a peripheral area surrounding the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree for the subject area, and during the actual imaging of the subject, projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area is output to a console. [Effects of the Invention]

[0024] According to the technology of the present disclosure, even if the amount of projection data output to the console is reduced, it is possible to output projection data that includes the entire subject. [Brief explanation of the drawings]

[0025] [Figure 1]FIG. 1 is a diagram illustrating an example of the device configuration of a CT device. [Figure 2] FIG. 2 is a diagram illustrating an example of the functional configuration of a CT apparatus. [Figure 3] FIG. 10 is a diagram illustrating an example of a flowchart relating to a process of outputting projection data to a console. [Figure 4] 10A and 10B are diagrams illustrating an example of a subject region, a peripheral region, and an enlarged subject region. [Figure 5] FIG. 10 is a diagram showing an example of projection data including a reference channel. [Figure 6] FIG. 10 is a diagram illustrating an example of a flowchart of an image display process. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, the present embodiment will be described with reference to the drawings. The same components and processes are denoted by the same reference numerals throughout the drawings, and duplicated explanations will be omitted. The dimensional proportions in the drawings are exaggerated for the sake of explanation, and may differ from the actual proportions.

[0027] FIG. 1 is a diagram showing an example of the device configuration of a CT device 11 according to the technology of the present disclosure. The CT device 11 uses radiation (e.g., X-rays) to capture an image of a region of a subject H to be imaged, i.e., the subject, to obtain a tomographic image of the subject. The CT device 11 is installed, for example, in an imaging room of a radiology department in a medical facility. The CT device 11 includes a gantry 16 and a console 17. The console 17 functions as an operation terminal and control device for operating the gantry 16. The console 17 is operated by an operator such as a diagnostic radiologist. The console 17 also functions as an image processing device that generates a tomographic image by performing image processing on data output from the gantry 16. The console 17 also functions as a display device that displays the generated tomographic image.

[0028] FIG. 2 is a diagram showing an example of the functional configuration of the CT device 11. As shown in FIG. 2, the gantry 16 is a main part of the CT device 11 and includes a gantry 18 and a bed device 19. In addition to a front view of the gantry 16, FIG. 2 also shows a side view of the gantry 16 within a rectangular dashed-line frame. The bed device 19 has a tabletop 19A on which a subject H can be placed in a supine position. The subject H is placed in a position in which his or her body axis is aligned with the longitudinal direction of the tabletop 19A (the Z-axis direction of the gantry 16). The tabletop 19A is movable in the Z-axis direction. The gantry 18 has an overall annular shape and has a circular opening 18A in the center, the diameter of which is larger than the width of the tabletop 19A. During imaging, the tabletop 19A on which the subject H is placed moves in the Z-axis direction relative to the gantry 18 to enter the opening 18A. The imaging is performed while the top plate 19A is moved relative to the gantry 18.

[0029] A radiation source 21, a detector 22, and a frame 23 are arranged inside the gantry 18. The radiation source 21 irradiates radiation toward the subject H. The detector 22 is a radiation detector that detects radiation that has passed through the subject H. The radiation that has passed through the subject H is attenuated by interaction with structures such as organs and bones inside the subject H (such as absorption and scattering of radiation). Each structure has its own unique attenuation coefficient for radiation, and the radiation that has passed through the structure carries intensity information that reflects the attenuation coefficient of the structure. The detector 22 has a detection surface on which pixels are arranged two-dimensionally, and outputs a detection signal corresponding to radiation intensity information for each pixel on the detection surface. The detector 22 has an approximately arc-shaped configuration in accordance with the curvature of the gantry 18, and the detection surface is also curved.

[0030] The radiation source 21 and the detector 22 are disposed in opposing positions within the gantry 18, and rotate around the Z-axis while maintaining their opposing orientation. The frame 23 is annular and rotatably supports the radiation source 21 and the detector 22. During imaging, the gantry 16 rotates the radiation source 21 and the detector 22 around the subject H on the tabletop 19A, and detects projection data PD at multiple positions in the circumferential direction around the Z-axis corresponding to the body axis of the subject H, using the detector 22. During imaging, the tabletop 19A also moves in the Z-axis direction in synchronization with the rotation of the radiation source 21 and the detector 22. This allows radiation projection data PD to be acquired at each position around the body axis of the subject H.

[0031] In the gantry 16, the Y axis represents the height direction and the X axis represents the width direction. As an example, in the bed device 19, the subject H is placed in a supine position with the head side facing the gantry 18. Therefore, in imaging, the subject H enters the gantry 18 head-first, and the projection data PD is output in order from the head side to the feet side.

[0032] The DAS (Data Acquisition System) 25 collects the detection signals output by the detector 22, generates projection data PD for each position around the Z axis based on the collected detection signals, and outputs the generated projection data PD to the console 17.

[0033] The detector 22 is a multi-slice radiation detector. A multi-slice radiation detector is a radiation detector in which a plurality of photoelectric conversion elements are arranged along the body axis direction of the subject H, i.e., the slice direction, and along a direction perpendicular to the slice direction, i.e., the channel direction. As an example, it is assumed that m photoelectric conversion elements are arranged in the slice direction and n photoelectric conversion elements are arranged in the channel direction, forming a matrix of m rows and n columns. Therefore, the DAS 25 outputs projection data PD of a maximum of m rows and n columns to the console 17.

[0034] An irradiation field limiter 24 (also called a collimator) that limits the radiation irradiation field is disposed in front of the radiation source 21 in the irradiation direction. The irradiation field limiter 24 has an irradiation aperture whose outline is defined by a plurality of shielding plates that block radiation, and the size of the irradiation aperture can be changed by moving the shielding plates. A high-voltage generator 26 generates a high voltage to be supplied to the radiation source 21. The radiation source 21 and the detector 22 are electrically connected to the frame 23, for example, by a slip ring system, and power supply and data transmission / reception are performed via the slip ring. The slip-ring connection allows imaging to be performed while the radiation source 21 and the detector 22 are rotated in one direction without reversing the rotation direction.

[0035] The gantry 16 is provided with a gantry control unit 27. Based on instructions from the console 17, the gantry control unit 27 controls the rotation of the radiation source 21 and the detector 22, the movement of the top plate 19A, and other components of the gantry 16.

[0036] The imaging conditions of the CT apparatus 11 are set through the gantry control unit 27 by operating the console 17. The imaging conditions include the radiation irradiation conditions of the radiation source 21, as well as the imaging range and slice interval. The radiation irradiation conditions include the tube voltage (unit: kV), tube current (unit: mA), and radiation irradiation time (unit: msec) applied to the radiation source 21. The product of the tube current and the irradiation time defines the total radiation dose, which is called the mAs value. The irradiation field is adjusted, for example, in the XZ plane by changing the size of the irradiation opening of the irradiation field limiter 24. Note that when the radiation emitted by the radiation source 21 is a cone beam, the width of the irradiation field in the Z-axis direction can also be adjusted by adjusting the width of the irradiation opening of the irradiation field limiter 24 in the Z-axis direction. The imaging range in the Z-axis direction, such as the whole body of the subject H or the area from the chest to the abdomen, is adjusted by changing the movement range of the top board 19A.

[0037] Furthermore, it is also possible to change the imaging range of a slice image. A slice image is a tomographic image representing an XY plane, i.e., an axial cross section perpendicular to the body axis of subject H, and is generated by image reconstruction based on projection data PD, as will be described later. The imaging range of such a slice image in the XY plane is also called FOV (Field of View). For example, in an axial cross section of the chest of subject H, the size of the FOV can be changed so that the FOV is a relatively large area that can accommodate the entire chest, or a relatively small area such as a part of the chest.

[0038] On the other hand, since the number of pixels of the detector 22 is fixed, reducing the FOV increases the resolution of the captured slice image, while increasing the FOV decreases the resolution. For example, if the total number of pixels of the detector 22 that can be output to the console 17 (m × n in this case) is fixed to a predetermined value, increasing the number of pixels m in the slice direction requires decreasing the number of pixels n in the channel direction. If the FOV can be reduced, the resolution within the slice plane can be increased by narrowing the channel spacing while keeping the number of pixels n in the channel direction. Alternatively, by increasing the number of pixels in the slice direction instead of reducing the number of pixels in the channel direction, the slice spacing can be narrowed and the resolution in the body axis direction can be increased.

[0039] The console 17 includes a display 31, an input device 32, a storage 33, a communication unit 34, and a processor 36. The console 17 is configured, for example, based on a personal computer or the like, and its hardware configuration is similar to that of a general computer. The display 31 is, for example, a liquid crystal display, and displays an operation screen and captured slice images, etc. The input device 32 is a device through which an operator inputs operation instructions, and is configured by a keyboard, a mouse, etc.

[0040] The storage 33 is a data storage that stores various programs such as a control program that controls each part of the console 17. The various programs include an application program (AP) 37 that causes the processor 36 to function as a control device and image processing device of the CT device 11. Examples of the storage 33 include a hard disk drive (HDD) and a solid state drive (SSD). The storage 33 also temporarily stores projection data PD acquired from the gantry 16 and generated slice images. The application program 37 is an example of an "operating program" according to the technology of the present disclosure.

[0041] The communication unit 34 is a communication interface for communicating between the console 17 and external devices such as the gantry 16 and an external image DB (Data Base). The communication unit 34 is connected to a network (not shown) such as a LAN (Local Area Network) and / or a WAN (Wide Area Network), and performs transmission control in accordance with communication protocols defined by various wired or wireless communication standards.

[0042] The processor 36 functions as a control unit 36A that controls each unit of the console 17, and an image processing unit 36B that executes various types of image processing. The processor 36 is configured by, for example, a CPU (Central Processing Unit) and memory such as RAM (Random Access Memory). The CPU functions as the processor 36 by loading various programs, including an application program 37, from the storage 33 into the memory and executing the loaded programs. The processor 36 is an example of a "processor" according to the technology of the present disclosure.

[0043] The control unit 36A controls the gantry 16 via the gantry control unit 27 in accordance with instructions from the operator inputted from the input device 32. The image processing unit 36B executes slice image generation processing and MPR (Multi-planar Reconstruction) image generation.

[0044] The slice image generation process is a process of generating a tomographic image by performing image reconstruction based on the projection data PD acquired from the gantry 16. The reconstructed tomographic image is a tomographic image representing an axial cross section perpendicular to the body axis (Z axis) of the subject H.

[0045] An MPR image is a tomographic image that represents an arbitrarily specified cross section of subject H. In addition to axial cross sections, MPR images include images of sagittal cross sections, which are vertical cross sections of subject H, and coronal cross sections, which are horizontal cross sections of subject H. MPR image generation processing is a process in which an arbitrary cross section is specified for an isotropic 3D image, and an MPR image is generated by cutting out the specified arbitrary cross section. An isotropic 3D image is an image that has undergone isotropic processing to make the resolution in the X-axis, Y-axis, and Z-axis directions uniform, based on a slice volume that includes all slice images in the imaging range.

[0046] Hereinafter, slice images and MPR images will be collectively referred to as “tomographic images.” A tomographic image is an example of a “radiographic image” according to the technology of the present disclosure, and is also an example of a “tomographic model.”

[0047] Next, the output process of the projection data PD in the CT apparatus 11 to the console 17 will be described.

[0048] FIG. 3 is a diagram showing an example of a flowchart relating to the output processing of projection data PD to the console 17, which is executed by the CT apparatus 11 when an operator issues an instruction to photograph a subject.

[0049] It is assumed that, before issuing an instruction to photograph, the operator inputs information about the subject through the input device 32. The information about the subject includes, for example, attributes of the subject H and information about the region of the subject H to be photographed for a tomographic image.

[0050] The attributes of the subject H are information that indicates what kind of person the subject H is. The attributes of the subject H include, for example, the age, sex, and symptoms of the subject H, such as whether or not the subject H has dementia.

[0051] Furthermore, the information relating to the imaging region of the subject H for which the tomographic image is to be taken includes, for example, the name of the region of the subject H for which the tomographic image is to be taken, and the presence or absence of a tumor.

[0052] In step S10, the processor 36 captures a scanogram image of the subject H placed on the tabletop 19A. The scanogram image is an image of the subject H captured in advance to determine the imaging range of the radiographic image prior to the actual imaging of the subject H by the CT device 11.

[0053] In step S20, the processor 36 extracts the contour of the subject from the scanogram image or axial cross section captured in the process of step S10, and sets the subject region.

[0054] The processor 36 displays the FOV for the actual imaging on the display 31, superimposed on the scanogram image or the axial cross section. Before the actual imaging, the operator can further adjust the FOV displayed on the display 31. In this case, the processor 36 resets the FOV adjusted by the operator as the subject region.

[0055] The processor 36 may set the subject region by extracting the contour of the subject from the scanogram RawData, rather than from the scanogram image or the axial cross section. The scanogram RawData is data including the projection data PD of all channels C generated by the DAS 25, and is an example of "pre-generation data used to generate a scanogram image" according to the technology of the present disclosure.

[0056] When generating a scanogram image, the FOV specified for the scanogram image, i.e., the imaging range varies based on the scanogram FOV, so the scanogram image does not necessarily contain the projection data PD of all channels corresponding to the subject region. Therefore, setting the subject region from the scanogram RawData may result in higher accuracy in setting the subject region compared to setting the subject region from the scanogram image or axial cross section.

[0057] Furthermore, the processor 36 may set the subject region by extracting the contour of the subject from an optical image of the subject H captured along the body axis by a visible light camera, for example.

[0058] If the subject H does not move until the actual imaging, the position of the subject will not change either. Therefore, a tomographic image of the subject can be obtained by extracting projection data PD within a range equivalent to the subject region set by the processing in step S20 from the projection data PD obtained by the actual imaging and outputting the extracted projection data to the console 17. However, if the subject H moves after the scanogram image is captured, determining the range of the projection data PD to be output to the console 17 according to the range of the set subject region may result in a situation where the entire subject is not included in the tomographic image.

[0059] Therefore, in step S30, processor 36 calculates the margin degree for the subject region. The margin degree for the subject region is the region surrounding the subject region, and is the range outside the subject region where the subject is estimated to protrude from the subject region due to body movement, i.e., the size of the peripheral region.

[0060] For example, processor 36 calculates the margin degree according to the part of the subject to be imaged. When the subject is the chest, breathing of subject H causes body movement, but this body movement is smaller than that of parts such as the head. Therefore, processor 36 calculates the margin degree for each part according to the part of the subject. Specifically, when the subject is the chest, 5% of the number of channels corresponding to the subject area is set as the margin degree. The number of channels corresponding to the subject area is the number of channels included in the range from one end to the other end of the subject area in the channel direction in the projection data PD. On the other hand, when the subject is the head, 10% of the number of channels corresponding to the subject area is set as the margin degree.

[0061] The margin degree associated with each part is stored in advance in storage 33, and processor 36 can acquire the margin degree corresponding to the part of the subject to be imaged, which is input by the operator as information about the subject, from storage 33. The margin degree associated with each part stored in storage 33 can be modified by the operator. Therefore, the margin degrees of 5% and 10% shown above are merely examples, and there are no restrictions on the value of the margin degree for each part.

[0062] Note that processor 36 may set the margin degree for the subject region based on factors other than the body part of the subject. For example, children tend to have greater body movements than adults. Therefore, if the age of subject H falls within a range preset for the age of a child, processor 36 preferably sets the margin degree for the subject region to a value greater than the margin degree set for an adult subject H, even if the subject has the same body part. For example, if subject H's age is between 0 and 12 years old, processor 36 determines that subject H is a child. The age range for children is stored in storage 33 in advance and can be modified by the operator.

[0063] Furthermore, for example, if subject H has dementia, even if the operator instructs him / her not to move, subject H may not understand the instruction, and therefore tends to move more than subject H who does not have dementia. Therefore, if subject H has dementia, it is preferable that processor 36 set the margin degree for the subject area to a value greater than the margin degree set for subject H who does not have dementia.

[0064] In this way, the processor 36 may set the margin degree for the subject region according to the attributes of the subject H, such as age and symptoms. Naturally, the processor 36 may set the margin degree for the subject region by combining the part of the subject and the attributes of the subject H.

[0065] Attributes of subject H, such as age and symptoms, may be acquired from information about the subject input by the operator, but processor 36 may also estimate attributes of subject H that are identifiable from appearance using optical images of subject H. For example, a visible light camera (not shown) that captures visible light and creates an image is used to capture the optical images. Processor 36 estimates attributes of subject H that are identifiable from appearance, such as age, from the optical images of subject H captured by the visible light camera using a known image recognition method.

[0066] Further, the processor 36 may set the margin degree for the subject area from the imaging conditions of the tomographic image set by the operator, that is, the CT imaging protocol.

[0067] In step S40, the processor 36 calculates an enlarged subject area obtained by adding a peripheral area represented by the margin degree set by the process in step S30 to the subject area. The processor 36 stores the calculated enlarged subject area in the memory.

[0068] Based on the enlarged subject area, the processor 36 calculates a channel C corresponding to the range of the enlarged subject area. The channel C corresponding to the range of the enlarged subject area is the channel C that constitutes the smallest range including all the peripheral areas and the subject area in the projection data PD.

[0069] FIG. 4 is a diagram showing an example of a subject area, a peripheral area, and an enlarged subject area in the projection data PD when a tomogram of the subject H is taken along the Z axis. In FIG. 4, the channel C in the channel direction p above, and the channel C q below to this range is taken as the subject area. Here, p and q (0 < p < q) are integers representing the channel numbers for identifying the channel C, and take values of 0 or more and n (q < n) or less. m1 and m2 are integers of 1 or more.

[0070] In this case, the range of channel C p-m1 above, and the channel C p less than, and the range of channel C q exceeding, and the channel C q+m2 below is the peripheral area. Also, the range of channel C that combines the subject area and the peripheral area p-m1 above, and the channel C q+m2 below is the enlarged subject area. That is, in the example of FIG. 4, the channel C corresponding to the range of the enlarged subject area is among the n photoelectric conversion elements arranged in the channel direction, the channel C p-m1 above, and the channel C q+m2It is a group of channels C each consisting of a photoelectric conversion element array corresponding to each channel C described below.

[0071] When an instruction for actual imaging is received from the operator, the processor 36 performs actual imaging of the subject in accordance with the CT imaging protocol set by the operator in step S50 of Fig. 3. As a result, the DAS 25 generates projection data PD of m rows x n columns.

[0072] In step S60, processor 36 acquires the enlarged object region stored in memory by the processing of step S40, and outputs only the projection data PD consisting of the channel C corresponding to the range of the enlarged object region, out of the m rows x n columns of projection data PD, to console 17. Information indicating the range of the enlarged object region is added to each projection data PD output to console 17.

[0073] This completes the process of outputting the projection data PD to the console 17 shown in FIG.

[0074] <Modification 1 of Output Processing of Projection Data PD> 3, the processor 36 may calculate the margin degree for each imaging direction of the subject, i.e., for each rotational direction of the radiation source 21 or each circumferential direction around the body axis of the subject H. For example, if the subject is the chest, body movement caused by breathing is greater in the Y-axis direction than in the X-axis direction. Therefore, the processor 36 may set the margin degree to 5% when imaging the subject H along the X-axis, and may set the margin degree to 7% when imaging the subject H along the Y-axis, for example.

[0075] By calculating the margin degree for each imaging direction of the subject, it is possible to set a larger margin degree in a direction where body movement is likely to occur than in other directions. Therefore, compared to when the margin degree is set without considering the imaging direction of the subject, it is possible to increase the probability that the entire subject is included in the projection data PD output to the console 17.

[0076] <Modification 2 of Output Processing of Projection Data PD> When the console 17 reconstructs a tomographic image based on the projection data PD, the reconstruction may be performed using a specific channel C as a reference. For convenience of explanation, the channel C referred to as a reference will be specifically referred to as a "reference channel C." x "

[0077] Figure 5 shows the reference channel C x 5 is a diagram showing an example of projection data PD including the reference channel C shown in FIG. x For example, the console 17 is connected to the reference channel C x When the projection data PD is corrected using the reference channel C x Therefore, the processor 36 needs to include a reference channel C that the console 17 uses to reconstruct a tomographic image of the object in addition to the channel C corresponding to the range of the enlarged object region. x are also included in the projection data PD and output to the console 17.

[0078] In addition, the reference channel C shown in Figure 5 x The position of the reference channel C x is not limited to the channel C corresponding to the end of the projection data PD.

[0079] <Modification 3 of Output Processing of Projection Data PD> In order to reduce the amount of radiation exposure to the subject H associated with capturing a tomographic image, it is preferable to avoid irradiating radiation onto areas other than the subject as much as possible.

[0080] Therefore, when performing actual imaging of the subject in the processing of step S50 in Figure 3, processor 36 may control irradiation field limiter 24 based on the enlarged subject area calculated by the processing of step S40 in Figure 3 so as not to irradiate radiation outside the range of the enlarged subject area.

[0081] <Tomographic image reconstruction processing> FIG. 6 is a diagram showing an example of a flowchart of the image display process executed by the console 17 upon receiving the projection data PD.

[0082] In step S100, the processor 36 performs image reconstruction based on the acquired projection data PD to generate a tomographic image of the subject.

[0083] In step S110, the processor 36 adjusts the FOV of the tomographic image of the subject reconstructed from the projection data PD in accordance with the number of channels included in the projection data PD. As a result, the display range of the tomographic image is autonomously adjusted by the processor 36, and a tomographic image that displays the entire subject as large as possible is obtained.

[0084] In step S120, the processor 36 displays on the display 31 the tomographic image of the subject with the adjusted FOV.

[0085] This completes the image display process shown in FIG.

[0086] If necessary, the operator can readjust the FOV of the tomographic image displayed on the display 31. In this case, the processor 36 displays the tomographic image on the display 31 in accordance with the FOV adjusted by the operator.

[0087] Furthermore, processor 36 may set the pixel values ​​of pixels in a range corresponding to an area outside the enlarged subject area to a predetermined value (for example, 0 value) when displaying a tomographic image of the subject on display 31. By setting the pixel values ​​of pixels in a range corresponding to an area outside the enlarged subject area to a predetermined value, it is possible to suppress the display of areas other than the subject in the tomographic image.

[0088] In this way, the CT device 11 according to the technique of the present disclosure calculates the margin degree for the subject region according to the part of the subject to be imaged, and calculates an enlarged subject region by adding a peripheral region represented by the margin degree to the subject region. When performing actual imaging of the subject, the CT device 11 outputs to the console 17 only the projection data PD of channel C corresponding to the range of the enlarged subject region from among the projection data PD generated by the DAS 25.

[0089] Therefore, even if the amount of output data of the projection data PD output to the console 17 is reduced, a tomographic image including the entire subject can be reconstructed from the output projection data PD.

[0090] While one form of the CT device 11 has been described above using the embodiment, the disclosed form of the CT device 11 is merely an example, and the form of the CT device 11 is not limited to the scope described in the embodiment. Various changes or improvements can be made to the embodiment without departing from the gist of the present disclosure, and forms incorporating such changes or improvements are also included in the technical scope of the disclosure.

[0091] For example, the internal processing order in the flowchart of the output process shown in FIG. 3 and the flowchart of the image display process shown in FIG. 6 may be changed without departing from the gist of the present disclosure.

[0092] In the above embodiment, the output process and image display process are implemented by software as an example. However, the processes equivalent to those shown in the flowcharts of each process may be implemented by hardware. In this case, the process speed can be increased compared to when each process is implemented by software.

[0093] In each of the above embodiments, the processor 36 refers to a processor in a broad sense, including general-purpose processors and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

[0094] Furthermore, the operations of the processor 36 in the above embodiment may not only be performed by one processor 36, but may also be performed by a plurality of processors 36 located at physically separate locations working together. Furthermore, the order of the operations of the processor 36 is not limited to the order described in the above embodiment, and may be changed as appropriate.

[0095] In the above embodiment, an example has been described in which the application program 37 is stored in the storage 33. However, the storage destination of the application program 37 is not limited to the storage 33. The application program 37 can also be provided in a form in which it is recorded on a computer-readable storage medium.

[0096] For example, the application program 37 may be provided in a form recorded on an optical disk such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), or a Blu-ray disc. The application program 37 may also be provided in a form recorded on a portable semiconductor memory such as a USB (Universal Serial Bus) memory or a memory card. The storage 33, a CD-ROM, a DVD-ROM, a Blu-ray disc, a USB, and a memory card are examples of non-transitory storage media.

[0097] Furthermore, the processor 36 may download an application program 37 from an external device connected to the network via the communication unit 34, and store the downloaded application program 37 in the storage 33. The present disclosure may also be applied to programs and program products.

[0098] The following additional notes are further disclosed regarding the above embodiment.

[0099] (Appendix 1) a processor; The processor: Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area is output to a console. CT device.

[0100] (Appendix 2) The processor calculates the margin degree according to the part of the subject to be photographed. CT device as described in Appendix 1.

[0101] (Appendix 3) The processor calculates the margin level according to attributes of the person who is the subject. CT device as described in Appendix 1.

[0102] (Appendix 4) The processor estimates attributes of the object from an optical image of the object. CT device as described in Appendix 3.

[0103] (Appendix 5) The processor resets the display range of the subject area that is set in advance in accordance with an instruction from an operator before actual photographing of the subject. CT device as described in Appendix 1.

[0104] (Appendix 6) The processor sets the object region based on a cross-sectional model of the object generated using pre-generation data used to generate a scanogram image, or on an optical image of the object. CT device as described in Appendix 1.

[0105] (Appendix 7) The processor: The margin degree is calculated for each imaging direction of the subject, and in the actual imaging of the subject, projection data of a channel corresponding to the range of the subject area to which the peripheral area expressed by the margin degree has been added is output to a console. 10. A CT device according to any one of Supplementary Notes 1 to 6.

[0106] (Appendix 8) The processor outputs to the console projection data including a specific channel that the console refers to in order to reconstruct a tomographic image of the object in addition to a channel corresponding to the range of the enlarged object region. A CT device according to any one of Supplementary Notes 1 to 7.

[0107] (Appendix 9) The processor controls an irradiation field limiter that limits the radiation field so as not to irradiate radiation outside the range of the enlarged subject region. A CT device according to any one of Supplementary Note 1 to Supplementary Note 8.

[0108] (Appendix 10) The processor adjusts a display range of the tomographic image of the subject reconstructed from the projection data according to the number of channels included in the projection data received by the console, and displays the tomographic image of the subject with the adjusted display range on a display device. A CT device according to any one of Supplementary Note 1 to Supplementary Note 9.

[0109] (Appendix 11) The processor readjusts the display range adjusted in accordance with the number of channels included in the projection data in accordance with an instruction from a user. 11. The CT device of claim 10.

[0110] (Appendix 12) The processor sets pixel values ​​of pixels in a range corresponding to an area outside the enlarged object area in the tomographic image of the object to a predetermined value. 12. The CT device of claim 10 or 11.

[0111] (Appendix 13) On the computer, Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, a process is executed to output to a console projection data of a channel corresponding to the range of an enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area. CT device operating program.

[0112] (Appendix 14) Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; A computer program product including a program that causes a computer to output to a console, in the actual photography of the subject, projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area.

[0113] (Appendix 15) Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, the computer is caused to execute a process of outputting to a console projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area. How a CT machine works. [Explanation of symbols]

[0114] 11 CT device 16 Mounting stand 17 Console 18 Gantry 18A Gantry opening 19 Bed Device 19A Top plate 21 Radiation source 22 Detector 23 frames 24 Irradiation field limiter 26 High Voltage Generator 27 Mounting control unit 31 Display 32 Input Devices 33 Storage 34 Communications Department 36 processors 36A Control Unit 36B Image processing unit 37 Application Programs C channel C x Reference Channel H. Subject PD projection data

Claims

1. a processor; The processor: Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area is output to a console. CT device.

2. The processor calculates the margin degree according to the part of the subject to be photographed. The CT device according to claim 1.

3. The processor calculates the margin level according to attributes of the person who is the subject. The CT device according to claim 1.

4. The processor estimates attributes of the object from an optical image of the object. The CT apparatus according to claim 3.

5. The processor resets the display range of the subject area that is set in advance in accordance with an instruction from an operator before actual photographing of the subject. The CT device according to claim 1.

6. The processor sets the object region based on a tomographic model of the object generated using pre-generation data used to generate a scanogram image, or on an optical image of the object. The CT device according to claim 1.

7. The processor: The margin degree is calculated for each imaging direction of the subject, and in the actual imaging of the subject, projection data of a channel corresponding to the range of the subject area to which the peripheral area expressed by the margin degree has been added is output to a console. The CT device according to claim 1.

8. The processor outputs to the console projection data including a specific channel that the console refers to in order to reconstruct a tomographic image of the object in addition to a channel corresponding to the range of the enlarged object region. The CT device according to claim 1.

9. The processor controls an irradiation field limiter that limits the radiation field so as not to irradiate radiation outside the range of the enlarged subject region. The CT device according to claim 1.

10. The processor adjusts a display range of the tomographic image of the subject reconstructed from the projection data according to the number of channels included in the projection data received by the console, and displays the tomographic image of the subject with the adjusted display range on a display device. The CT apparatus according to any one of claims 1 to 9.

11. The processor readjusts the display range adjusted in accordance with the number of channels included in the projection data in accordance with an instruction from an operator. The CT apparatus according to claim 10.

12. The processor sets pixel values ​​of pixels in a range corresponding to an area outside the enlarged object area in the tomographic image of the object to a predetermined value. The CT apparatus according to claim 10.

13. On the computer, Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, a process is executed to output to a console projection data of a channel corresponding to the range of an enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area. CT device operating program.

14. Using information about the subject, a subject area is set in the imaging range of the radiation image; Before the actual imaging of the subject, a size of a peripheral area around the subject area, in a range outside the subject area where the subject is estimated to protrude from the subject area due to body movement, is calculated as a margin degree with respect to the subject area; In the actual imaging of the subject, the computer is caused to execute a process of outputting to a console projection data of a channel corresponding to the range of the enlarged subject area obtained by adding the peripheral area represented by the margin degree to the subject area. How the CT machine works.

Images