JP6855173B2 - X-ray CT device - Google Patents

Description

Embodiments of the present invention relate to an X-ray CT apparatus.

Conventionally, in radiography using an X-ray CT apparatus (CT; Computed Tomography), a scan protocol for collecting data is set according to an examination site and an examination content. The above-mentioned scan protocol is set by selecting a scan protocol candidate suitable for the inspection site and the inspection content from a plurality of preset scan protocol candidates and adjusting the preset conditions as appropriate. Here, each scan protocol candidate is classified according to, for example, physique such as age, adult / child, male / female, weight, height, inspection purpose, etc., and a positioning image (scano image) for setting a shooting range. ) Shooting range, scanning angle of scanno image, tube voltage and tube current when shooting a positioning image, scan method of main shooting (scan) for collecting data used for diagnosis, scan position, scan range, scan Various conditions such as tube voltage and tube current, position and range of image reconstruction, etc. are set in advance.

Here, in the X-ray CT apparatus, before scanning, the history of exposure to each organ of the subject and the exposure information to each organ of this imaging are numerically and color information on a three-dimensional scanno image by helical scanning. The technique of displaying by is known. Further, there is also known a technique of calculating the exposure dose for each organ or tissue of a subject based on the scan conditions and superimposing the calculated exposure dose on the model data and displaying it.

JP-A-2007-181623 Japanese Unexamined Patent Publication No. 2014-054392 Japanese Unexamined Patent Publication No. 2008-012229 Japanese Unexamined Patent Publication No. 2012-010759

An object to be solved by the present invention is to provide an X-ray CT apparatus capable of easily performing radiography in consideration of exposure to each part.

The X-ray CT apparatus of the embodiment includes a collecting unit, a calculating unit, and a setting unit. The collecting unit collects projection data by detecting X-rays that have passed through the subject. The calculation unit determines the X-ray irradiation conditions preset in the second scan of the part of the subject included in the three-dimensional image data reconstructed from the projection data collected by the first scan of the subject. Calculate the exposure information in. The setting unit adjusts and sets the X-ray irradiation conditions of the second scan for the subject based on the exposure information of the site.

FIG. 1 is a diagram showing an example of a configuration of a medical information processing system according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 3 is a diagram for explaining three-dimensional scanno image capture by the scan control unit according to the first embodiment. FIG. 4A is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 4B is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 5 is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 6 is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 7 is a diagram showing an example of a virtual patient image stored by the storage circuit according to the first embodiment. FIG. 8 is a diagram for explaining an example of collation processing by the position collation function according to the first embodiment. FIG. 9 is a diagram showing an example of conversion of the scan range by coordinate conversion according to the first embodiment. FIG. 10 is a diagram showing an example of setting the scan range according to the first embodiment. FIG. 11 is a diagram showing an example of exposure information calculated by the calculation function according to the first embodiment. FIG. 12 is a diagram showing an example of a coefficient for calculating the effective dose for each part according to the first embodiment. FIG. 13 is a diagram for explaining a threshold value for each part according to the first embodiment. FIG. 14A is a diagram showing an example of display information regarding X-ray irradiation conditions according to the first embodiment. FIG. 14B is a diagram showing an example of display information regarding X-ray irradiation conditions according to the first embodiment. FIG. 15 is a diagram showing an example of display information regarding radiation exposure according to the first embodiment. FIG. 16 is a diagram showing an example of display information regarding radiation exposure according to the first embodiment. FIG. 17 is a diagram showing an example of display information regarding radiation exposure according to the first embodiment. FIG. 18 is a diagram showing an example of display information regarding radiation exposure according to the first embodiment. FIG. 19 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the first embodiment.

Hereinafter, embodiments of an X-ray CT (Computed Tomography) apparatus will be described in detail with reference to the accompanying drawings. Hereinafter, a medical information processing system including an X-ray CT apparatus will be described as an example. In the medical information processing system 100 shown in FIG. 1, only one server device and one terminal device are shown, but in reality, a plurality of server devices and terminal devices can be further included. Further, the medical information processing system 100 can also include, for example, a medical image diagnostic device such as an X-ray diagnostic device, an MRI (Magnetic Resonance Imaging) device, and an ultrasonic diagnostic device.

(First Embodiment)
FIG. 1 is a diagram showing an example of the configuration of the medical information processing system 100 according to the first embodiment. As shown in FIG. 1, the medical information processing system 100 according to the first embodiment includes an X-ray CT device 1, a server device 2, and a terminal device 3. The X-ray CT device 1, the server device 2, and the terminal device 3 can communicate with each other directly or indirectly by, for example, an in-hospital LAN (Local Area Network) 4 installed in the hospital. It has become. For example, when a PACS (Picture Archiving and Communication System) is introduced in the medical information processing system 100, each device transmits and receives medical images and the like to and from each other in accordance with the DICOM (Digital Imaging and Communications in Medicine) standard.

Further, in the medical information processing system 100, for example, HIS (Hospital Information System) and RIS (Radiology Information System) are introduced to manage various information. For example, the terminal device 3 transmits the inspection order created according to the above system to the X-ray CT device 1 and the server device 2. The X-ray CT device 1 acquires patient information from a patient list (modality work list) for each modality created by an examination order directly received from the terminal device 3 or a server device 2 that has received the examination order, and the patient. Collect X-ray CT image data for each. Then, the X-ray CT apparatus 1 transmits the collected X-ray CT image data and the image data generated by performing various image processing on the X-ray CT image data to the server apparatus 2. The server device 2 stores the X-ray CT image data and the image data received from the X-ray CT device 1, generates image data from the X-ray CT image data, and responds to the acquisition request from the terminal device 3. The data is transmitted to the terminal device 3. The terminal device 3 displays the image data received from the server device 2 on a monitor or the like. Hereinafter, each device will be described.

The terminal device 3 is a device that is arranged in each medical department in the hospital and operated by a doctor working in each medical department, and is a PC (Personal Computer), a tablet PC, a PDA (Personal Digital Assistant), a mobile phone, or the like. Is. For example, in the terminal device 3, medical record information such as a patient's symptom and a doctor's findings is input by a doctor. Further, the terminal device 3 is input with an inspection order for ordering the inspection by the X-ray CT device 1, and transmits the input inspection order to the X-ray CT device 1 and the server device 2. That is, the doctor in the clinical department operates the terminal device 3 to read the reception information of the patient who visited the hospital and the information of the electronic medical record, examine the corresponding patient, and input the medical record information into the read electronic medical record. Then, the doctor in the clinical department operates the terminal operation 3 to transmit the examination order according to the necessity of the examination by the X-ray CT apparatus 1.

The server device 2 stores medical images (for example, X-ray CT image data and image data collected by the X-ray CT device 1) collected by the medical image diagnostic device, and performs various image processing on the medical image. It is a device for performing, for example, a PACS server. For example, the server device 2 receives a plurality of examination orders from the terminal devices 3 arranged in each clinical department, creates a patient list for each medical image diagnosis device, and creates the created patient list for each medical image diagnosis device. Send to. As an example, the server device 2 receives an examination order for performing an examination by the X-ray CT device 1 from the terminal device 3 of each clinical department, creates a patient list, and X-rays the created patient list. It is transmitted to the CT device 1. Then, the server device 2 stores the X-ray CT image data and the image data collected by the X-ray CT device 1, and in response to the acquisition request from the terminal device 3, the X-ray CT image data and the image data are stored in the terminal device. Send to 3.

The X-ray CT apparatus 1 collects X-ray CT image data for each patient, and uses the collected X-ray CT image data and image data generated by performing various image processing on the X-ray CT image data as a server. It is transmitted to the device 2. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the first embodiment. As shown in FIG. 2, the X-ray CT apparatus 1 according to the first embodiment includes a gantry 10, a sleeper apparatus 20, and a console 30.

The gantry 10 is a device that irradiates the subject P (patient) with X-rays, detects the X-rays transmitted through the subject P, and outputs the X-rays to the console 30. The X-ray irradiation control circuit 11 and the X-ray generator are generated. It has a device 12, a detector 13, a data acquisition circuit (DAS: Data Acquisition System) 14, a rotating frame 15, and a gantry drive circuit 16.

The rotating frame 15 supports the X-ray generator 12 and the detector 13 so as to face each other with the subject P in between, and rotates at high speed in a circular orbit centered on the subject P by a gantry drive circuit 16 described later. It is an annular frame.

The X-ray irradiation control circuit 11 is a device that supplies a high voltage to the X-ray tube 12a as a high voltage generating unit, and the X-ray tube 12a uses the high voltage supplied from the X-ray irradiation control circuit 11 to X. Generate a line. The X-ray irradiation control circuit 11 adjusts the X-ray dose to be irradiated to the subject P by adjusting the tube voltage and the tube current supplied to the X-ray tube 12a under the control of the scan control circuit 33 described later. ..

Further, the X-ray irradiation control circuit 11 switches the wedge 12b. Further, the X-ray irradiation control circuit 11 adjusts the X-ray irradiation range (fan angle and cone angle) by adjusting the opening degree of the collimator 12c. In this embodiment, the operator may manually switch between a plurality of types of wedges.

The X-ray generator 12 is a device that generates X-rays and irradiates the subject P with the generated X-rays, and has an X-ray tube 12a, a wedge 12b, and a collimator 12c.

The X-ray tube 12a is a vacuum tube that irradiates the subject P with an X-ray beam by a high voltage supplied by a high voltage generating unit (not shown), and the X-ray beam is sent to the subject P as the rotating frame 15 rotates. Irradiate against. The X-ray tube 12a generates an X-ray beam that spreads with a fan angle and a cone angle. For example, under the control of the X-ray irradiation control circuit 11, the X-ray tube 12a is continuously exposed to X-rays all around the subject P for full reconstruction, or half-reconstructable for half-reconstruction. It is possible to continuously expose X-rays within the range (180 degrees + fan angle). Further, under the control of the X-ray irradiation control circuit 11, the X-ray tube 12a can intermittently emit X-rays (pulse X-rays) at a preset position (tube position). The X-ray irradiation control circuit 11 can also modulate the intensity of X-rays exposed from the X-ray tube 12a. For example, the X-ray irradiation control circuit 11 increases the intensity of X-rays emitted from the X-ray tube 12a at a specific tube position, and exposes the X-ray tube 12a to a range other than the specific tube position. Decreases the intensity of the emitted X-rays.

The wedge 12b is an X-ray filter for adjusting the X-ray dose of X-rays exposed from the X-ray tube 12a. Specifically, the wedge 12b transmits the X-rays exposed from the X-ray tube 12a so that the X-rays radiated from the X-ray tube 12a to the subject P have a predetermined distribution. It is a filter that attenuates. For example, the wedge 12b is a filter obtained by processing aluminum so as to have a predetermined target angle and a predetermined thickness. The wedge is also called a wedge filter or a bow-tie filter.

The collimator 12c is a slit for narrowing down the X-ray irradiation range in which the X-ray dose is adjusted by the wedge 12b under the control of the X-ray irradiation control circuit 11 described later.

The gantry drive circuit 16 rotates the rotating frame 15 to rotate the X-ray generator 12 and the detector 13 on a circular orbit centered on the subject P.

The detector 13 is a two-dimensional array type detector (surface detector) that detects X-rays that have passed through the subject P, and the detection element sequence formed by arranging X-ray detection elements for a plurality of channels is the subject P. A plurality of rows are arranged along the body axis direction (Z-axis direction shown in FIG. 2). Specifically, the detector 13 in the first embodiment has X-ray detection elements arranged in multiple rows such as 320 rows along the body axis direction of the subject P, for example, the lungs of the subject P. It is possible to detect X-rays that have passed through the subject P over a wide range, such as the area including the heart and the heart.

The data collection circuit 14 is a DAS and collects projection data from the X-ray detection data detected by the detector 13. For example, the data acquisition circuit 14 generates projection data by performing amplification processing, A / D conversion processing, sensitivity correction processing between channels, and the like on the X-ray intensity distribution data detected by the detector 13. The projected projection data is transmitted to the console 30 described later. For example, when X-rays are continuously exposed from the X-ray tube 12a during the rotation of the rotating frame 15, the data collection circuit 14 collects the projection data group for the entire circumference (360 degrees). Further, the data collection circuit 14 associates the tube position with each of the collected projection data and transmits the data to the console 30 described later. The tube position is information indicating the projection direction of the projection data. The sensitivity correction processing between channels may be performed by the preprocessing circuit 34, which will be described later.

The sleeper device 20 is a device on which the subject P is placed, and has a sleeper drive device 21 and a top plate 22 as shown in FIG. The sleeper drive device 21 moves the top plate 22 in the Z-axis direction to move the subject P into the rotating frame 15. The top plate 22 is a plate on which the subject P is placed.

The gantry 10 executes, for example, a helical scan in which the rotating frame 15 is rotated while the top plate 22 is moved to spirally scan the subject P. Alternatively, the gantry 10 executes a conventional scan in which the rotating frame 15 is rotated while the position of the subject P is fixed after the top plate 22 is moved to scan the subject P in a circular orbit. Alternatively, the gantry 10 executes a step-and-shoot method in which the position of the top plate 22 is moved at regular intervals to perform a conventional scan in a plurality of scan areas.

The console 30 is a device that accepts the operation of the X-ray CT device 1 by the operator and reconstructs the X-ray CT image data using the projection data collected by the gantry 10. As shown in FIG. 2, the console 30 includes an input circuit 31, a display 32, a scan control circuit 33, a preprocessing circuit 34, a storage circuit 35, an image reconstruction circuit 36, and a processing circuit 37. ..

The input circuit 31 has a mouse, keyboard, trackball, switch, button, joystick, etc. used by the operator of the X-ray CT device 1 to input various instructions and various settings, and information on the instructions and settings received from the operator. Is transferred to the processing circuit 37. For example, the input circuit 31 receives from the operator the imaging conditions for the X-ray CT image data, the reconstruction conditions for reconstructing the X-ray CT image data, the image processing conditions for the X-ray CT image data, and the like. In addition, the input circuit 31 accepts an operation for selecting a test for a subject. Further, the input circuit 31 accepts a designation operation for designating a portion on the image.

The display 32 is a monitor referred to by the operator, and under the control of the processing circuit 37, the display 32 displays the image data generated from the X-ray CT image data to the operator, or the operator via the input circuit 31. Displays a GUI (Graphical User Interface) for receiving various instructions and settings from. In addition, the display 32 displays a plan screen for a scan plan, a screen during scanning, and the like. In addition, the display 32 displays a virtual patient image including exposure information, image data, and the like. The virtual patient image displayed by the display 32 will be described in detail later.

The scan control circuit 33 controls the operations of the X-ray irradiation control circuit 11, the gantry drive circuit 16, the data acquisition circuit 14, and the sleeper drive device 21 under the control of the processing circuit 37 to control the operation of the projection data on the gantry 10. Control the collection process. Specifically, the scan control circuit 33 controls the collection process of projection data in the imaging for collecting the positioning image (scano image) and the main imaging (scan) for collecting the image used for diagnosis. Here, in the X-ray CT apparatus 1 according to the first embodiment, a two-dimensional scanno image and a three-dimensional scanno image can be taken.

For example, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees (a position in the front direction with respect to the subject), and continuously shoots while moving the top plate at a constant speed. Take a dimensional scanno image. Alternatively, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees, moves the top plate intermittently, and intermittently repeats imaging in synchronization with the movement of the top plate to obtain two-dimensional images. Take a scanno image. Here, the scan control circuit 33 can capture a positioning image from an arbitrary direction (for example, a side surface direction) as well as the front direction with respect to the subject.

In addition, the scan control circuit 33 captures a three-dimensional scanno image by collecting projection data for the entire circumference of the subject when capturing the scanno image. FIG. 3 is a diagram for explaining three-dimensional scanno image capture by the scan control circuit 33 according to the first embodiment. For example, as shown in FIG. 3, the scan control circuit 33 collects projection data for the entire circumference of the subject by helical scan or non-helical scan. Here, the scan control circuit 33 executes a helical scan or a non-helical scan on a wide area such as the entire chest, abdomen, upper body, and whole body of the subject at a lower dose than the main imaging. As the non-helical scan, for example, the above-mentioned step-and-shoot method scan is executed.

In this way, the scan control circuit 33 collects the projection data for the entire circumference of the subject, so that the image reconstruction circuit 36 described later reconstructs the three-dimensional X-ray CT image data (volume data). As shown in FIG. 3, it becomes possible to generate a positioning image from an arbitrary direction using the reconstructed volume data. Here, whether to capture the positioning image in two dimensions or in three dimensions may be arbitrarily set by the operator, or may be preset according to the inspection content.

Returning to FIG. 2, the preprocessing circuit 34 performs logarithmic conversion processing and correction processing such as offset correction, sensitivity correction, and beam hardening correction on the projection data generated by the data acquisition circuit 14. Generate corrected projection data. Specifically, the preprocessing circuit 34 generates corrected projection data for each of the projection data of the positioning image generated by the data acquisition circuit 14 and the projection data collected by the main shooting, and the storage circuit 35. Store in.

The storage circuit 35 stores the projection data generated by the preprocessing circuit 34. Specifically, the storage circuit 35 stores the projection data of the positioning image generated by the preprocessing circuit 34 and the projection data for diagnosis collected by the main imaging. Further, the storage circuit 35 stores the image data and the virtual patient image generated by the image reconstruction circuit 36 described later. Further, the storage circuit 35 appropriately stores the processing result by the processing circuit 37 described later. The virtual patient image and the processing result by the processing circuit 37 will be described later.

The image reconstruction circuit 36 reconstructs the X-ray CT image data using the projection data stored in the storage circuit 35. Specifically, the image reconstruction circuit 36 reconstructs the X-ray CT image data from the projection data of the positioning image and the projection data of the image used for diagnosis. Here, as the reconstruction method, there are various methods, and examples thereof include a back projection process. Further, as the back projection process, for example, a back projection process by the FBP (Filtered Back Projection) method can be mentioned. Alternatively, the image reconstruction circuit 36 can reconstruct the X-ray CT image data by using the successive approximation method.

Further, the image reconstruction circuit 36 generates image data by performing various image processing on the X-ray CT image data. Then, the image reconstruction circuit 36 stores the reconstructed X-ray CT image data and the image data generated by various image processes in the storage circuit 35.

The processing circuit 37 controls the operation of the gantry 10, the sleeper device 20, and the console 30 to control the entire X-ray CT device 1. Specifically, the processing circuit 37 controls the CT scan performed on the gantry 10 by controlling the scan control circuit 33. Further, the processing circuit 37 controls the image reconstruction processing and the image generation processing in the console 30 by controlling the image reconstruction circuit 36. Further, the processing circuit 37 controls the display 32 to display various image data stored in the storage circuit 35.

Further, as shown in FIG. 2, the processing circuit 37 executes the detection function 37a, the position matching function 37b, the calculation function 37c, the setting function 37d, and the display control function 37e. Here, for example, each processing function executed by the detection function 37a, the position matching function 37b, the calculation function 37c, the setting function 37d, and the display control function 37e, which are the components of the processing circuit 37 shown in FIG. 2, can be executed by a computer. It is recorded in the storage circuit 35 in the form of a program. The processing circuit 37 is a processor that realizes a function corresponding to each program by reading each program from the storage circuit 35 and executing the program. In other words, the processing circuit 37 in the state where each program is read has each function shown in the processing circuit 37 of FIG. The calculation function 37c described in the present embodiment corresponds to the calculation unit described in the claims. Further, the setting function 37d corresponds to the setting unit described in the claims. Further, the display control function 37e corresponds to the output control unit described in the claims. Further, the detection function 37a corresponds to the detection unit described in the claims.

The word "processor" used in the above description is, for example, a CPU (central processing unit), a GPU (Graphics Processing Unit), an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC), or a programmable logic device (ASIC). For example, it means a circuit such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). The processor realizes the function by reading and executing the program stored in the storage circuit. Instead of storing the program in the storage circuit, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit. It should be noted that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent circuits may be combined to form one processor to realize its function. Good.

The detection function 37a detects each of a plurality of sites in the subject included in the three-dimensional image data. Specifically, the detection function 37a detects a part such as an organ included in the three-dimensional X-ray CT image data (volume data) reconstructed by the image reconstruction circuit 36. For example, the detection function 37a detects a site such as an organ based on an anatomical landmark of at least one of the volume data of the positioning image and the volume data of the image used for diagnosis. Here, the anatomical feature point is a point showing the feature of a specific part such as a bone, an organ, a blood vessel, a nerve, or a lumen. That is, the detection function 37a detects bones, organs, blood vessels, nerves, lumens, etc. included in the volume data by detecting anatomical feature points such as specific organs and bones. In addition, the detection function 37a can also detect the positions of the head, neck, chest, abdomen, legs, etc. included in the volume data by detecting the characteristic feature points of the human body. The site described in the present embodiment means a bone, an organ, a blood vessel, a nerve, a lumen, or the like including these positions. Hereinafter, an example of detecting a portion by the detection function 37a will be described.

For example, the detection function 37a extracts anatomical feature points from the voxel values included in the volume data in the volume data of the positioning image or the volume data of the image used for diagnosis. Then, the detection function 37a compares the three-dimensional position of the anatomical feature point in the information such as a textbook with the position of the feature point extracted from the volume data to obtain the feature point extracted from the volume data. Inaccurate feature points are removed from the inside to optimize the position of the feature points extracted from the volume data. As a result, the detection function 37a detects each part of the subject included in the volume data. As an example, the detection function 37a first extracts anatomical feature points included in the volume data by using a supervised machine learning algorithm. Here, the above-mentioned supervised machine learning algorithm is constructed by using a plurality of supervised images in which correct anatomical feature points are manually arranged, and is used by, for example, a decision forest. Will be done.

Then, the detection function 37a optimizes the extracted feature points by comparing the model showing the three-dimensional positional relationship of the anatomical feature points in the body with the extracted feature points. Here, the above-mentioned model is constructed by using the above-mentioned teacher image, and for example, a point distribution model or the like is used. That is, the detection function 37a is a model in which the shape and positional relationship of the part, points unique to the part, etc. are defined based on a plurality of teacher images in which correct anatomical feature points are manually arranged, and the extracted features. By comparing with points, inaccurate feature points are removed and feature points are optimized.

Hereinafter, an example of the site detection process by the detection function 37a will be described with reference to FIGS. 4A, 4B, 5 and 6. 4A, 4B, 5 and 6 are diagrams for explaining an example of a portion detection process by the detection function 37a according to the first embodiment. In FIGS. 4A and 4B, the feature points are arranged two-dimensionally, but in reality, the feature points are arranged three-dimensionally. For example, the detection function 37a applies a supervised machine learning algorithm to the volume data to extract voxels regarded as anatomical feature points as shown in FIG. 4A (black dots in the figure). Then, the detection function 37a fits the position of the extracted voxels to a model in which the shape and positional relationship of the parts, points unique to the parts, etc. are defined, and as shown in FIG. 4B, among the extracted voxels. Inaccurate feature points are removed and only voxels corresponding to more accurate feature points are extracted.

Here, the detection function 37a assigns an identification code for identifying the feature points indicating the features of each part to the extracted feature points (voxels), and the identification code and the position (coordinate) information of each feature point. The information associated with and is attached to the image data and stored in the storage circuit 35. For example, as shown in FIG. 4B, the detection function 37a assigns identification codes such as C1, C2, and C3 to the extracted feature points (voxels). Here, the detection function 37a attaches an identification code to each of the data for which the detection process has been performed, and stores the data in the storage circuit 35. Specifically, the detection function 37a is performed from at least one of the projection data of the positioning image, the projection data collected under non-contrast, and the projection data collected in the state of being imaged by the contrast medium. The site of the subject contained in the reconstructed volume data is detected.

For example, as shown in FIG. 5, the detection function 37a attaches information associated with the coordinates of each voxel detected from the volume data (positioning in the figure) of the positioning image to the volume data to the storage circuit 35. Store in. As an example, the detection function 37a extracts the coordinates of the marking point from the volume data of the positioning image, and as shown in FIG. 5, "identification code: C1, coordinates (x ₁ , y ₁ , z ₁ )". , "identification code: C2, coordinates _{(x 2, y 2, z} 2) " storing in association with such a volume data. Thereby, the detection function 37a can identify what kind of feature point is in which position in the volume data of the positioning image, and can detect each part such as an organ based on this information.

Further, as shown in FIG. 5, for example, the detection function 37a attaches information in which an identification code is associated with the coordinates of each voxel detected from the volume data (scan in the figure) of the image for diagnosis to the volume data. Is stored in the storage circuit 35. Here, the detection function 37a is labeled from the volume data (contrast-enhanced Phase in the figure) imaged by the contrast medium and the volume data (non-contrast-enhanced Phase in the figure) not contrast-enhanced by the contrast medium in the scan. The coordinates of the points can be extracted and the identification code can be associated with the extracted coordinates.

As an example, the detection function 37a extracts the coordinates of the marking point from the volume data of the non-contrast phase from the volume data of the image for diagnosis, and as shown in FIG. 5, "identification code: C1, coordinates. _{(x '1, y' 1} , z '1) "," identification code: C2, coordinates _{(x' 2, y '2} , z' 2) "storing in association with such a volume data. The detection function 37a, among the volume data of the image for diagnosis, and extracting coordinates of landmark from the volume data of the contrast Phase, as shown in FIG. 5, "identification code: C1, coordinates (x _{'1 , y '1, z' 1} ) "," identification code: C2, coordinates _{(x '2, y' 2} , z '2) "storing in association with such a volume data. Here, when the labeled points are extracted from the volume data of the contrast-enhanced Phase, the labeled points that can be extracted by being contrast-enhanced are included. For example, the detection function 37a can extract blood vessels and the like imaged by a contrast agent when extracting labeled points from the volume data of the contrast-enhanced Phase. Therefore, when the volume data of the contrast Phase, detection 37a, as shown in FIG. 5, the coordinates of the landmark, such as a blood vessel extracted by contrast _{(x '31, y' 31} , z '31) ~ such as the coordinate _{(x '34, y' 34} , z '34), the identification code C31 for identifying each vessel, C32, associates and C33 and C34.

As described above, the detection function 37a can identify what kind of marker point is in which position in the volume data of the positioning image or the diagnostic image, and based on this information, the organ or the like can be identified. Each site can be detected. For example, the detection function 37a detects the position of the target site by using the information of the anatomical positional relationship between the target site to be detected and the site around the target site. As an example, when the target site is the "lung", the detection function 37a acquires the coordinate information associated with the identification code indicating the characteristics of the lung, and also obtains the "ribs", "clavicle", and "heart". , The coordinate information associated with the identification code indicating the surrounding part of the "lung" such as the "diaphragm" is acquired. Then, the detection function 37a extracts the region of the "lung" in the volume data by using the information of the anatomical positional relationship between the "lung" and the surrounding portion and the acquired coordinate information.

For example, the detection function 37a is based on the positional relationship information such as "lung apex: 2-3 cm above the clavicle" and "lower end of the lung: height of the 7th rib" and the coordinate information of each part. As shown in, the region R1 corresponding to the “lung” in the volume data is extracted. That is, the detection function 37a extracts the coordinate information of the voxels in the region R1 in the volume data. The detection function 37a associates the extracted coordinate information with the part information, attaches it to the volume data, and stores it in the storage circuit 35. Similarly, as shown in FIG. 6, the detection function 37a can extract the region R2 and the like corresponding to the “heart” in the volume data.

Further, the detection function 37a detects a position included in the volume data based on a feature point that defines a position of the head, chest, or the like in the human body. Here, the positions of the head, chest, etc. in the human body can be arbitrarily defined. For example, if the area from the 7th cervical spine to the lower end of the lung is defined as the chest, the detection function 37a detects from the feature point corresponding to the 7th cervical spine to the feature point corresponding to the lower end of the lung as the chest. The detection function 37a can detect the site by various methods other than the method using the above-mentioned anatomical feature points. For example, the detection function 37a can detect a portion included in the volume data by a region expansion method based on a voxel value or the like.

The position matching function 37b collates the positions of the plurality of parts in the subject included in the three-dimensional image data with the positions of the plurality of parts in the human body included in the virtual patient data. Here, the virtual patient data is information representing a standard position of each of a plurality of parts in the human body. That is, the position collation function 37b collates the position of the part of the subject with the position of the standard part, and stores the collation result in the storage circuit 35. For example, the position matching function 37b matches a virtual patient image in which a part of the human body is arranged at a standard position with a volume data of a subject.

Here, first, a virtual patient image will be described. The virtual patient image is an image actually taken by X-ray of a human body having a standard physique according to multiple combinations of parameters related to physique such as age, adult / child, male / female, weight, and height. It is generated in advance and stored in the storage circuit 35. That is, the storage circuit 35 stores data of a plurality of virtual patient images according to the combination of the above-mentioned parameters. Here, anatomical feature points (feature points) are associated with and stored in the virtual patient image stored by the storage circuit 35. For example, the human body has a large number of anatomical features that can be relatively easily extracted from an image based on its morphological features and the like by image processing such as pattern recognition. The positions and arrangements of these many anatomical features in the body are roughly determined according to the physique such as age, adult / child, male / female, weight, and height.

In the virtual patient image stored by the storage circuit 35, a large number of these anatomical feature points are detected in advance, and the position data of the detected feature points is attached to the data of the virtual patient image together with the identification code of each feature point. Or it is associated and stored. FIG. 7 is a diagram showing an example of a virtual patient image stored by the storage circuit 35 according to the first embodiment. For example, as shown in FIG. 7, the storage unit 35 has identification codes “V1”, “V2” and identification codes “V1”, “V2” for identifying anatomical feature points and feature points on a three-dimensional human body including a part such as an organ. A virtual patient image associated with "V3" or the like is stored.

That is, the storage circuit 35 stores the coordinates of the feature points in the coordinate space of the three-dimensional human body image in association with the corresponding identification code. As an example, the storage circuit 35 stores the coordinates of the corresponding feature points in association with the identification code “V1” shown in FIG. Similarly, the storage circuit 35 stores the identification code and the coordinates of the feature point in association with each other. Although only the lungs, heart, liver, stomach, kidneys, etc. are shown as organs in FIG. 7, the virtual patient image actually includes a larger number of organs, bones, blood vessels, nerves, and the like. .. Further, in FIG. 7, only the feature points corresponding to the identification codes “V1”, “V2” and “V3” are shown, but in reality, a larger number of feature points are included.

The position matching function 37b matches the feature points in the volume data of the subject detected by the detection function 37a with the feature points in the virtual patient image described above by using the identification code, and matches the coordinate space of the volume data. Associate with the coordinate space of the virtual patient image. FIG. 8 is a diagram for explaining an example of collation processing by the position collation function 37b according to the first embodiment. Here, in FIG. 8, matching is performed using three sets of feature points to which identification codes indicating the same feature points are assigned between the feature points detected from the scanno image and the feature points detected from the virtual patient image. However, the embodiment is not limited to this, and matching can be performed using any set of feature points.

For example, as shown in FIG. 8, the position matching function 37b has the feature points indicated by the identification codes “V1”, “V2” and “V3” in the virtual patient image, and the identification codes “C1” and “C2” in the scanno image. When matching with the feature points indicated by "" and "C3", the coordinate space between the images is associated by performing coordinate transformation so that the positional deviation between the same feature points is minimized. For example, as shown in FIG. 8, the position matching function 37b has the same anatomically the same feature points “V1 (x1, y1, z1), C1 (X1, Y1, Z1)” and “V2 (x2, y2, z2). ), C2 (X2, Y2, Z2) ”,“ V3 (x3, y3, z3), C3 (X3, Y3, Z3) ”so as to minimize the total“ LS ”of the positional deviation below. Find the coordinate conversion matrix "H".

LS = ((X1, Y1, Z1) -H (x1, y1, z1))
+ ((X2, Y2, Z2) -H (x2, y2, z2))
+ ((X3, Y3, Z3) -H (x3, y3, z3))

The position matching function 37b can convert the scan range specified on the virtual patient image into the scan range on the positioning image by the obtained coordinate transformation matrix “H”. For example, the position matching function 37b uses the coordinate transformation matrix “H” to change the scan range “SRV” specified on the virtual patient image to the scan range “SRC” on the positioning image, as shown in FIG. Can be converted. FIG. 9 is a diagram showing an example of conversion of the scan range by coordinate conversion according to the first embodiment. For example, as shown on the virtual patient image of FIG. 9, when the operator sets the scan range “SRV” on the virtual patient image, the position matching function 37b uses the coordinate transformation matrix described above to perform the set scan. Convert the range "SRV" to the scan range "SRC" on the scanno image.

As a result, for example, the scan range "SRV" set to include the feature points corresponding to the identification code "Vn" on the virtual patient image has the identification code "Cn" corresponding to the same feature points on the scanno image. Is converted and set to the scan range "SRC" including. The coordinate transformation matrix "H" described above may be stored in the storage circuit 35 for each subject and appropriately read out and used, or calculated each time a scanno image is collected. It may be the case. As described above, according to the first embodiment, the virtual patient image is displayed for specifying the range at the time of presetting, and the position / range is planned on the virtual patient image, so that after the positioning image (scano image) is taken. , The position / range on the positioning image corresponding to the planned position / range can be automatically set numerically.

Returning to FIG. 2, the calculation function 37c calculates the exposure information of the site detected by the detection function 37a. The setting function 37d sets the X-ray irradiation condition based on the exposure information calculated by the calculation function 37c. The display control function 37e controls the display 32 to display various display information. For example, the display control function 37e controls the display 32 to display various image data stored in the storage circuit 35. In addition, the display control function 37e controls the exposure information to be displayed on the display 32. The details of the calculation function 37c, the setting function 37d, and the display control function 37c will be described in detail later.

The overall configuration of the X-ray CT apparatus 1 according to the first embodiment has been described above. Under such a configuration, the X-ray CT apparatus 1 according to the first embodiment makes it possible to easily perform imaging in consideration of exposure to each part. As described above, in the conventional X-ray CT apparatus, there is known a technique of superimposing and displaying exposure information for each site on an image or the like. Therefore, the X-ray CT apparatus 1 according to the first embodiment can easily take an image in consideration of the exposure of each part in addition to displaying the exposure information for each part by the control by the processing circuit 37 described in detail below. Allows you to do.

Specifically, in the X-ray CT apparatus 1 according to the first embodiment, the part of the subject included in the three-dimensional image data reconstructed from the projection data collected by the first scan on the subject. In the second scan, the exposure information under the preset X-ray irradiation conditions is calculated. Then, the X-ray CT apparatus 1 adjusts and sets the X-ray irradiation condition of the second scan for the subject based on the exposure information of the site. That is, in the X-ray CT apparatus 1 according to the present embodiment, the exposure information received in the main scan is calculated for each part irradiated with the X-ray by the main scan, and the X-ray in the main scan is calculated based on the calculated exposure information. Adjust the irradiation conditions.

For example, in the current X-ray CT apparatus 1, the X-ray irradiation conditions in this scan are preset according to the scan range (scan target). In the X-ray CT apparatus 1 according to the present embodiment, it is calculated how much the part to be scanned is exposed when X-rays are irradiated under preset irradiation conditions, and the calculated exposure exceeds a predetermined threshold value. By adjusting the X-ray irradiation conditions so that there is no such thing, imaging is performed in consideration of the exposure of each part.

Hereinafter, a case where the scan range of the main scan is determined using the scanno image and the exposure information for each part included in the determined scan range is calculated will be described as an example. FIG. 10 is a diagram showing an example of setting the scan range according to the first embodiment. Here, in FIG. 10, a plan screen of a scan plan is shown, and a virtual patient image and a scanno image are shown on the plan screen. Although only the virtual patient image and the scanno image are shown in FIG. 10, various images displayed on the plan screen of the scan plan are actually displayed.

For example, when the scanno image is collected, the display control function 37e displays the virtual patient image and the scanno image on the display 32 as shown in FIG. 10, and accepts the setting of the scan range of the main scan. Here, as shown in FIG. 10, when the scanno image is collected, the detection function 37a detects a portion included in the volume data of the scanno image as described above. Then, the position matching function 37b executes a matching process between the coordinate information of the actually collected scanno image and the coordinate information of the virtual patient image based on the feature points of the detected portion. Thereby, for example, even when the scan range of the main scan is set on the scanno image shown on the right side of FIG. 10, the set scan range can be arranged at an accurate position on the virtual patient image. Alternatively, conversely, even when the scan range of the main scan is set on the virtual patient image, the set scan range can be arranged at an accurate position on the scanno image.

It is also possible to set the scan range at the site using, for example, a virtual patient image. For example, by designating a part such as the heart, lungs, chest, or abdomen on the virtual patient image, the corresponding scan range can be automatically set. For example, the scan range “R11” shown in FIG. 10 can be set by any of the above-mentioned methods.

For example, as shown in FIG. 10, when the scan range “R11” of the main scan is set after collecting the scanno image, the calculation function 37c extracts the part included in the scan range “R11” and extracts the extracted part. The exposure information for each main scan is calculated. For example, the calculation function 37c extracts parts such as "lung", "heart", "liver", "stomach", and "kidney" included in "R11" based on the coordinate information of the scan range "R11". ..

Then, the calculation function 37c calculates the exposure information for each extracted part. Here, the calculation function 37c calculates the effective dose for each site using, for example, "DLP (Dose Length Product)". Here, "DLP (mGy · cm)" is obtained by multiplying the absorbed dose "CTDI _Vol (mGy)" measured by the CTDI (CT Dose Index) phantom by the X-ray irradiation range in the body axis direction. The "CTDI _Vol (mGy)" is measured in advance by a CTDI phantom having a diameter of "160 mm" for the head and a CTDI phantom having a diameter of "320 mm" for the abdomen under various conditions, and is stored in the X-ray CT apparatus 1. .. _{That is, the DLP is calculated from the "CTDI Vol} (mGy)" corresponding to each X-ray irradiation condition and the X-ray irradiation range.

The calculation function 37c calculates the effective dose for each site by multiplying the "DLP" calculated according to the X-ray irradiation conditions of this scan by the coefficient for each "tissue / organ". For example, the calculation function 37c is a scan calculated based on CTDI measured in advance using a CTDI phantom having a diameter of "320 mm" for the abdomen in the main scan targeting the scan range "R11" of the chest and abdomen. By multiplying the "DLP" according to the protocol by the coefficient for each "tissue / organ", for example, the exposure information for each site as shown in FIG. 11 is calculated. FIG. 11 is a diagram showing an example of exposure information calculated by the calculation function 37c according to the first embodiment.

For example, as shown in FIG. 11, the calculation function 37c calculates the exposure information “effective dose (mSv)” for each “region within the region” that is a region included in the scan range “R11”. As an example, the calculation function 37c calculates the "effective dose: aaaa (mSv)" of the "lung" by multiplying the value of the "DLP" calculated according to the scan conditions by the coefficient of the "lung". .. Similarly, the calculation function 37c calculates the "effective dose: bbbb (mSv)" of the "heart" by multiplying the value of the "DLP" by the coefficient of the "heart". Further, the calculation function 37c calculates the "effective dose: cccc (mSv)" of the "liver" by multiplying the value of the "DLP" by the coefficient of the "liver". In this way, the calculation function 37c calculates the effective dose at each site by multiplying the value of "DLP" calculated according to the scan conditions of this scan by the coefficient for each site.

Here, the calculation function 37c can use various coefficients as the coefficients for each part. FIG. 12 is a diagram showing an example of a coefficient for calculating the effective dose for each part according to the first embodiment. FIG. 12 shows the coefficients defined in “ICRP (International Commission on Radiological Protection)”. For example, as shown in FIG. 12, (tissue / organ: coefficient) = (genital organ: 0.08), (red bone marrow: 0.12), (colon: 0.12), (lung: 0.12), (Stomach: 0.12), (Bladder: 0.04), (Breast: 0.12), (Liver: 0.04), (Esophagus: 0.04), (Thyroid: 0.04), (Skin : 0.01), (brain: 0.01), etc. are defined.

For example, the calculation function 37c refers to the coefficient of FIG. 12 and multiplies the value of “DLP” by the coefficient “0.12” of “lung” to obtain “effective dose: aaaa (mSv)” of “lung”. Is calculated. In addition to the example shown in FIG. 12, there are various coefficients for calculating the effective dose for each part. The calculation function 37c may use these coefficients properly. For example, since the recommended coefficient differs depending on the race, the coefficient may be used properly according to the race of the subject.

As described above, when the exposure information is calculated by the calculation function 37c, the setting function 37d adjusts and sets the X-ray irradiation condition of the second scan for the subject based on the exposure information of the site. Specifically, the setting function 37d sets the X-ray irradiation condition of the second scan so that the exposure of the portion detected by the detection function 37a is equal to or less than a predetermined threshold value based on the exposure information. FIG. 13 is a diagram for explaining a threshold value for each part according to the first embodiment. For example, as shown in FIG. 13, a threshold value of "effective dose (mSv)" is set for each site.

For example, the setting function 37d compares the "effective dose: aaaa" and the "threshold: ddddd" of the "lung", and when the "effective dose: aaaa" exceeds the threshold, the "effective dose: aaaa" The X-ray irradiation condition is adjusted so that "" is equal to or less than "threshold value: ddddd". That is, the setting function 37d adjusts the X-ray irradiation conditions so that the effective dose of each part is equal to or less than the threshold value as compared with the threshold value for each part. As an example, the setting function 37d irradiates X-rays so that the effective dose at each site is below the threshold by adjusting conditions such as tube voltage (kV), tube current (mA), and irradiation time. Adjust the conditions.

The display control function 37e controls so that the exposure information for each part is displayed on the display 32. For example, the display control function 37e controls the display 32 to display information such as effective dose information for each site calculated by the calculation function 37c and X-ray irradiation conditions. Further, the display control function 37e controls the display 32 to display information such as effective dose information for each part after the X-ray irradiation condition is adjusted by the setting function 37d and information such as the X-ray irradiation condition. ..

14A and 14B are diagrams showing an example of display information regarding X-ray irradiation conditions according to the first embodiment. Here, in FIGS. 14A and 14B, the modulation curve of the tube current at the time of the main scan in the scan range “R11” is shown. For example, as shown in FIG. 14A, the display control function 37e causes the display 32 to display the display information in which the horizontal axis is the tube current and the modulation curve 51 of the tube current is shown on the scanno image.

Here, the modulation curve 51 shown in FIG. 14A shows the modulation of the tube current in the body axis direction. That is, a modulation curve 51 is shown in which the scan is started at "Head first", the tube current is gradually increased, the maximum tube current is reached near the shoulder, and then the tube current is increased or decreased. For example, the setting function 37d modulates the tube current in the body axis direction as shown in FIG. 14A so that the effective dose for each part is equal to or less than the threshold value.

Further, FIG. 14B shows a tube current modulation curve 52 in the XY plane. Here, in the modulation curve 52, the distance from the center represents the magnitude of the tube current. That is, the tube current in the Y-axis direction (Lateral direction) becomes the maximum, and the tube current becomes the minimum in the "AP (Anterior Posterior) direction". For example, the setting function 37d modulates the tube current in the XY plane as shown in FIG. 14B so that the effective dose for each part is equal to or less than the threshold value. The display control function 37e receives permission to change the irradiation conditions by presenting the X-ray irradiation conditions as shown in FIGS. 14A and 14B to the operator before and after the adjustment by the setting function 37d.

Further, the display control function 37e controls the display 32 to display various exposure information of the subject in addition to the information regarding the X-ray irradiation conditions. 15 to 18 are diagrams showing an example of display information regarding radiation exposure according to the first embodiment. For example, as shown in FIG. 15, the display control function 37e causes the display 32 to display the display information in which the exposure information is superimposed on the site of the virtual patient image. Here, the display control function 37e superimposes and displays the exposure information for each site before adjustment calculated by the calculation function 37c on the virtual patient image. For example, when the operator selects the “heart” on the virtual patient image, the display control function 37e superimposes the effective dose “gggggmSv” of the heart on the virtual patient image as shown in FIG.

Here, as shown in FIG. 15, the display control function 37e can display the exposure information of only the selected part, but the exposure information is simultaneously displayed for all the parts for which the effective dose is calculated by the calculation function 37c. It can also be displayed. Further, the display control function 37e can similarly display the effective dose calculated under the condition after the X-ray irradiation condition is adjusted by the setting function 37d on the virtual patient image.

Further, as shown in FIG. 16, the display control function 37e can add information on the body thickness and surface area to the virtual patient image to display the display information on the display 32. Here, in FIG. 16, a scale of body thickness is shown below each virtual patient image. The scale below the front-facing virtual patient image indicates the size of the virtual patient image in the "Lateral" direction. That is, the curve 53 on the virtual patient image facing the front is a curve showing the body thickness in the "Lateral" direction in the actual subject. For example, as shown in curve 53, the body thickness in the "Lateral" direction at the neck is thinner, and the body thickness in the "Lateral" direction near the shoulders is the thickest.

Also, the scale below the sideways virtual patient image indicates the size of the body thickness of the virtual patient image in the "AP" direction. That is, the curve 54 on the virtual patient image facing sideways is a curve showing the body thickness in the "AP" direction in the actual subject. For example, as shown in curve 54, the body thickness in the "AP" direction at the neck is thinner, and the body thickness in the "AP" direction near the chest is the thickest.

Further, as shown in FIG. 16, the display control function 37e arranges an arrow that can be freely moved in the vertical direction in the horizontal direction of the virtual patient image, and the operator vertically moves the arrow via the input circuit 31. By operating the slide, it is also possible to display the surface area of the subject at that position. Here, for example, the display control function 37e displays the body thickness which is the intersection of the dotted line extending from the arrow and the curve 53 as "body thickness: m cm", and the body which is the intersection of the dotted line extending from the arrow and the curve 54. The thickness is displayed as "body thickness: l cm". In addition, the "surface area: n cm ² " of the subject at the position of the dotted line is shown next to the arrow. That is, the operator slides the arrow via the input circuit 31 to display the display information displaying the actual surface area and body thickness information of the subject on the display 32.

The above-mentioned display information is merely an example, and the display control function 37e can appropriately display other information. For example, the display control function 37e can also display past information on the surface area and body thickness of the actual subject. In such a case, for example, the storage circuit 35 stores information on the surface area and body thickness for each subject. Then, the display control function 37e reads the past information of the current subject from the storage circuit 35 and displays it on the display 32. As an example, the display control function 37e simultaneously displays past information on the surface area and body thickness display portion shown in FIG. 16, or displays past information in response to a switching operation by the operator.

Here, the surface area and body thickness of the subject can be calculated from the volume data of the collected scanno images. In addition, the surface area and body thickness of each part of the subject can also be calculated from the detection result by the detection function 37a and the volume data of the scanno image. Further, the body thickness of the subject may be calculated by a method of reducing X-rays. Further, although not shown, the volume of each part may be calculated. These calculations may be performed by the calculation function 37c.

When the surface area and body thickness are calculated in this way, the display control function 37e presents exposure information considering not only the simple effective dose but also the surface area, body thickness, or volume, as shown in FIG. be able to. For example, as shown in FIG. 16, the display control function 37e has, for the heart, "effective dose: gggg mSv", "hhh mSv" in which the effective dose is surface-corrected, and "hhh mSv" in which the body thickness is corrected. "iiiii mSv" and the like can be calculated and displayed. Here, at present, the index value of the dose corresponding to the physique of the subject is attracting attention. For example, in "AAPM (American Association of Physicist in Medicine)", "CTDI" is corrected by the body thickness. "SSDE (Size Specific Dose Estimation)" and the like are known. According to this embodiment, it is possible to provide a new index value of dose using not only body thickness but also surface area and volume.

Here, in the X-ray CT apparatus 1 according to the present embodiment, a three-dimensional scanno image is collected. As a result, the X-ray CT apparatus 1 can accurately calculate the length of the body thickness of the subject and the amount of X-ray absorption for each view. Therefore, the X-ray CT apparatus 1 can more accurately provide an index value of a dose commensurate with the physique of the subject, including the above-mentioned "SSDE".

Further, as shown in FIG. 17, the display control function 37e can display the display information in which the image is colorized according to the exposure dose. Further, as shown in FIG. 18, the display control function 37e can display the DPL in accordance with the scan time sequence, or can display the effective dose for each site in a graph. For example, as shown in FIG. 18, the display control function 37e can simultaneously display a graph of each part on the scan planning screen with the horizontal axis as the effective dose (mSv).

Next, the processing of the X-ray CT apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 19 is a flowchart showing a processing procedure by the X-ray CT apparatus 1 according to the first embodiment. Steps S101 and S102 shown in FIG. 19 are steps in which the processing circuit 37 reads a program corresponding to the processing function from the storage circuit 35 and executes the program. In step S101, the processing circuit 37 determines whether or not the inspection has been started. Then, in step S102, the processing circuit 37 collects the three-dimensional positioning image by controlling the scan control circuit 33, the image reconstruction circuit 36, and the like.

Step S103 of FIG. 19 is a step executed by the input circuit 31. In step S103, the input circuit 31 accepts the setting of the scan range based on the positioning image. Step S104 of FIG. 19 is a step in which the processing circuit 37 reads a program corresponding to the calculation function 37c from the storage circuit 35 and executes the program. In step S104, the processing circuit 37 calculates the exposure information based on the scan conditions.

Step S105 of FIG. 19 is a step in which the processing circuit 37 reads a program corresponding to the setting function 37d from the storage circuit 35 and executes the program. In step S105, the processing circuit 37 sets the scan conditions so that the exposure dose for each part is equal to or less than a predetermined threshold value. Step S106 of FIG. 19 is a step in which the processing circuit 37 reads a program corresponding to the display control function 37e from the storage circuit 35 and executes the program. In step S106, the processing circuit 37 displays the exposure information.

As described above, according to the first embodiment, the data collection circuit 14 collects the projection data by detecting the X-rays that have passed through the subject. The calculation function 37c is under the X-ray irradiation conditions preset in the second scan of the part of the subject included in the three-dimensional image data reconstructed from the projection data collected by the first scan of the subject. The exposure information of is calculated. The setting function 37d adjusts and sets the X-ray irradiation condition of the second scan for the subject based on the exposure information of the site. Therefore, the X-ray CT apparatus 1 according to the first embodiment makes it possible to easily perform imaging in consideration of exposure to each part.

Further, according to the first embodiment, the detection function 37a detects the site of the subject included in the three-dimensional image data. The setting function 37d sets the X-ray irradiation condition of the second scan so that the exposure of the portion detected by the detection function 37a is equal to or less than a predetermined threshold value based on the exposure information. Therefore, the X-ray CT apparatus 1 according to the first embodiment makes it possible to appropriately reduce the exposure.

Further, according to the first embodiment, the calculation function 37c calculates the size of the portion detected by the detection function 37a, and calculates the exposure information in the second scan according to the calculated size. The setting function 37d sets the X-ray irradiation condition of the second scan based on the exposure information. In addition, the calculation function 37c calculates the body thickness of the subject, and calculates the exposure information of the part of the subject in the second scan according to the calculated body thickness. The setting function 37d sets the X-ray irradiation condition of the second scan so that the exposure of the part of the subject in the second scan is equal to or less than a predetermined threshold value based on the exposure information calculated by the calculation function 37c. .. Therefore, the X-ray CT apparatus 1 according to the first embodiment enables more accurate exposure evaluation.

Further, according to the first embodiment, the display control function 37e controls to output the exposure information of the part of the subject calculated by the calculation function 37c. Further, the display control function 37e controls to output an image showing the exposure information to at least one of the display image and the human body model image generated from the three-dimensional image data. Therefore, the X-ray CT apparatus 1 according to the first embodiment can provide exposure information.

(Second embodiment)
By the way, although the first embodiment has been described so far, it may be implemented in various different forms other than the above-mentioned first embodiment.

Further, each component of each device shown in the first embodiment is a functional concept, and does not necessarily have to be physically configured as shown in the figure. That is, the specific form of distribution / integration of each device is not limited to the one shown in the figure, and all or part of the device is functionally or physically distributed / physically in arbitrary units according to various loads and usage conditions. Can be integrated and configured. Further, each processing function performed by each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

Further, the control method described in the first embodiment can be realized by executing a control program prepared in advance on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. Further, this control program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and being read from the recording medium by the computer.

As described above, according to each embodiment, it is possible to easily perform imaging in consideration of exposure to each part.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 X-ray CT device 14 Data collection circuit 37a Detection function 37b Position matching function 37c Calculation function 37d Setting function 37e Display control function

Claims (5)

A collection unit that collects projection data by detecting X-rays that have passed through the subject,
Exposure information under the X-ray irradiation conditions preset in the second scan of the site of the subject included in the three-dimensional image data reconstructed from the projection data collected by the first scan of the subject. And a calculation unit that calculates at least one of the body thickness and body surface area of the subject based on the three-dimensional image data.
A setting unit that adjusts and sets the X-ray irradiation conditions of the second scan for the subject based on the exposure information of the site.
A display screen including a human body model image and an instruction unit that can move along the body axis direction of the human body model image is displayed, and in response to the movement of the instruction unit, the human body model image instructed by the instruction unit is displayed. and exposure information corresponding to the position, a display control unit for displaying at least one information of the body thickness and body surface area corresponding to those of said phase location,
An X-ray CT apparatus. A detection unit for detecting the site of the subject included in the three-dimensional image data is further provided.
The calculation unit calculates the exposure information of the part of the subject detected by the detection unit in the second scan.
The first aspect of the present invention, wherein the setting unit sets the X-ray irradiation condition of the second scan so that the exposure of the portion detected by the detection unit is equal to or less than a predetermined threshold value based on the exposure information. X-ray CT device. The calculation unit calculates the size of the portion detected by the detection unit, and calculates the exposure information in the second scan according to the calculated size.
The X-ray CT apparatus according to claim 2, wherein the setting unit sets X-ray irradiation conditions for the second scan based on the exposure information. The calculation unit calculates the exposure information of the part of the subject in the second scan according to the calculated body thickness of the subject.
Based on the exposure information calculated by the calculation unit, the setting unit sets the X-ray irradiation condition of the second scan so that the exposure of the part of the subject in the second scan is equal to or less than a predetermined threshold value. The X-ray CT apparatus according to any one of claims 1 to 3. The display controller, a display image image generated from the 3-dimensional image data, and controls to output an image showing the exposure information at the same time, according to any one of claims 1-4 X-ray CT device.

Images