JP6996881B2 - X-ray CT device - Google Patents

Description

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

When scanning a scan target portion whose size or position changes, the conventional X-ray CT apparatus sets a wide scan range. Further, the conventional X-ray CT apparatus ends the scan based on the instruction input by the user who confirms that the entire scan target portion has been scanned.

However, the scan target area whose size and position change may not fit within the wide set scan range. In this case, the conventional X-ray CT apparatus additionally scans the portion of the scan target portion that does not fit in the scan range and its periphery. Further, since the size and position of the scan target portion are not always the same as those at the time of the previous scan, the conventional X-ray CT apparatus generates three-dimensional CT image data including the seam. There is.

Further, the conventional X-ray CT apparatus is unnecessary until the user inputs an instruction to complete the scan if the moving speed of the top plate is fast even if the scan target part is within the wide set scan range. I sometimes scanned a large area.

Japanese Unexamined Patent Publication No. 2015-213949

An object to be solved by the present invention is to provide an X-ray CT apparatus capable of reliably scanning a scan target with a single scan.

The X-ray CT apparatus according to the embodiment includes an acquisition unit and a change unit. The acquisition unit acquires the scan target portion and the first scan range. While the scan target portion is being scanned, the changing unit changes the first scan range to the second scan range based on the projection data of the scan target portion collected by the scan.

FIG. 1 is a diagram showing an example of a configuration of an X-ray CT apparatus according to an embodiment. FIG. 2 is a flowchart showing an example of processing performed by the X-ray CT apparatus according to the embodiment. FIG. 3 is a diagram showing an example of the positional relationship between the lung and the first scan range depicted in the preliminary image data of the coronal plane of the subject. FIG. 4 is a diagram showing an example of partial image data of a cross section of a subject at the end of the first scan range. FIG. 5 is a diagram showing an example of the positional relationship between the lung position estimated by the X-ray CT apparatus according to the embodiment and the first scan range. FIG. 6 is a diagram showing an example of the positional relationship between the lung position estimated by the X-ray CT apparatus according to the embodiment and the second scan range. FIG. 7 is a diagram showing an example of partial image data of a cross section of a subject at the end of the second scan range. FIG. 8 is a diagram for explaining a case where scanning for a predetermined volume is further performed. FIG. 9 is a diagram for explaining a case where scanning for a predetermined volume is further performed.

Hereinafter, the X-ray CT apparatus according to the embodiment will be described with reference to the drawings. In the following embodiments, duplicate description will be omitted as appropriate.

(Embodiment)
The configuration of the X-ray CT apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 includes a gantry 10, a bed 20, and a console 30. The configuration of the X-ray CT apparatus 1 is not limited to the following configuration.

The gantry 10 includes a high voltage generation circuit 11, a collimator adjustment circuit 12, a gantry drive circuit 13, an X-ray irradiation device 14, a detector 15, a data acquisition circuit 16, and a rotating frame 17.

The high voltage generation circuit 11 supplies a tube voltage to the X-ray tube 141, which will be described later. The collimator adjusting circuit 12 adjusts the opening degree and the position of the collimator 143, which will be described later. As a result, the collimator adjustment circuit 12 adjusts the irradiation range of the X-rays that the X-ray tube 141 irradiates the subject P. The gantry drive circuit 13 rotates the rotating frame 17. As a result, the gantry drive circuit 13 swivels the X-ray irradiation device 14 and the detector 15 on a circular orbit centered on the subject P. The high voltage generation circuit 11, the collimator adjustment circuit 12, and the gantry drive circuit 13 realize their functions by reading and executing a program stored in the storage circuit 35, which will be described later. The high voltage generation circuit 11, the collimator adjustment circuit 12, and the gantry drive circuit 13 are realized by, for example, a processor.

The X-ray irradiation device 14 includes an X-ray tube 141, a wedge 142, and a collimator 143. The X-ray tube 141 irradiates the subject P with X-rays. The X-ray tube 141 generates beam-shaped X-rays by the tube voltage supplied by the high voltage generation circuit 11. This beam-shaped X-ray is also called a cone beam. The wedge 142 is an X-ray filter for adjusting the dose of X-rays emitted from the X-ray tube 141. The collimator 143 is a slit for adjusting the irradiation range of X-rays. The opening degree and position of the collimator 143 are adjusted by the collimator adjusting circuit 12. By adjusting the opening degree of the collimator 143, for example, the fan angle and the cone angle of the cone beam are adjusted.

The detector 15 has a detection element. These detection elements are regularly arranged in the first direction and the second direction intersecting the first direction. For example, the first direction is the circumferential direction of the rotating frame 17, and the second direction is the slice direction. Here, the slice direction is the body axis direction. The detection element detects the intensity of the incident X-ray. In addition, such a detector is called a multi-row detector.

The detection element includes a scintillator, a photodiode and a detection circuit. The input terminal of the detection circuit is connected to the output terminal of the photodiode. The output terminal of the detection circuit is connected to the input terminal of the data acquisition circuit 16.

The detection element detects the intensity of the incident X-ray by the following method. First, the detection element converts the incident X-rays into light by a scintillator. Next, the detection element converts the light into an electric charge by a photodiode. Then, the detection element converts this charge into an electric signal by the detection circuit and outputs it to the data acquisition circuit 16 described later. A detector equipped with a detection element having a scintillator and a photodiode is also referred to as a solid-state detector.

The data acquisition circuit 16 generates projection data based on the electric signal output by the detection element. The projection data is, for example, a synogram. The synogram is data in which the signals detected by the detector 15 at each position of the X-ray tube 141 are arranged. Here, the position of the X-ray tube 141 is called a view. The circumferential sequence of the rotating frame 17 of the detection element in a view is called a channel. The synogram is data in which the intensity of X-rays detected by the detector 15 is assigned to a two-dimensional Cartesian coordinate system in which the first direction is the view direction and the second direction orthogonal to the first direction is the channel direction of the detector 15. Is. The data acquisition circuit 16 generates a synogram in units of columns in the slice direction. The data acquisition circuit 16 is realized by, for example, a processor. The data acquisition circuit 16 is also called a DAS (Data Acquisition System).

The rotating frame 17 is an annular frame. The rotating frame 17 holds the X-ray irradiation device 14 and the detector 15 so as to face each other with the subject P interposed therebetween. The rotating frame 17 is driven by the gantry drive circuit 13 and rotates at high speed on a circular orbit centered on the subject P.

The bed 20 includes a top plate 21 and a bed drive circuit 22. The top plate 21 is a plate-shaped member on which the subject P is placed. The bed drive circuit 22 moves the subject P in the photographing port of the gantry 10 by moving the top plate 21 on which the subject P is placed in the body axis direction. The bed drive circuit 22 realizes its function by reading and executing a program stored in the storage circuit 35 described later. The bed drive circuit 22 is realized by, for example, a processor.

The console 30 includes an input circuit 31, a display 32, a projection data storage circuit 33, an image storage circuit 34, a storage circuit 35, and a processing circuit 36.

The input circuit 31 is used by a user who inputs instructions and settings. The input circuit 31 is included in, for example, a mouse and a keyboard. The input circuit 31 transfers the instructions and settings input by the user to the processing circuit 36. The input circuit 31 is realized by, for example, a processor.

The display 32 is a monitor referenced by the user. The display 32 is, for example, a liquid crystal display. The display 32 receives, for example, an instruction from the processing circuit 36 to display CT image data and a GUI (Graphical User Interface). As a result, the display 32 displays the CT image data and the GUI. The GUI is used when the user inputs instructions and settings. The CT image data means the CT image itself or the data that is the basis for displaying the CT image.

The projection data storage circuit 33 stores the projection data that has been preprocessed by the preprocessing function 362, which will be described later. The projection data preprocessed by the preprocessing function 362 is also referred to as raw data. The image storage circuit 34 stores preliminary image data, partial image data, and CT image data generated by the image generation function 363 described later.

The storage circuit 35 stores a program for the high voltage generation circuit 11, the collimator adjustment circuit 12, the gantry drive circuit 13, and the data acquisition circuit 16 to realize the above-mentioned functions. The storage circuit 35 stores a program for the bed drive circuit 22 to realize the above-mentioned functions. The storage circuit 35 stores a program for the processing circuit 36 to realize each of the functions described later.

The projection data storage circuit 33, the image storage circuit 34, and the storage circuit 35 have a storage medium in which the stored information can be read out by a computer. The storage medium is, for example, a hard disk.

The processing circuit 36 has a scan control function 361, a preprocessing function 362, an image generation function 363, an acquisition function 364, an estimation function 365, a change function 366, a notification function 367, and a control function 368. The control function 368 is a function of operating each component of the gantry 10, the bed 20, and the console 30 at an appropriate timing according to a purpose to execute a scan. Details of other functions will be described later. The processing circuit 36 is realized by, for example, a processor.

An example of the processing of the X-ray CT apparatus 1 according to the embodiment will be described with reference to FIGS. 2 to 7. FIG. 2 is a flowchart showing an example of processing performed by the X-ray CT apparatus 1 according to the embodiment. FIG. 3 is a diagram showing an example of the positional relationship between the lung and the first scan range depicted in the preliminary image data of the coronal plane of the subject P. FIG. 4 is a diagram showing an example of partial image data of a cross section of the subject P at the end of the first scan range. FIG. 5 is a diagram showing an example of the positional relationship between the lung position estimated by the X-ray CT apparatus according to the embodiment and the first scan range. FIG. 6 is a diagram showing an example of the positional relationship between the lung position estimated by the X-ray CT apparatus according to the embodiment and the second scan range. FIG. 7 is a diagram showing an example of partial image data of a cross section of the subject P at the end of the second scan range.

Hereinafter, a case where the X-ray CT apparatus 1 scans the lung C of the subject P from the head side to the abdomen side of the subject P will be described as an example. A site set as a scan target, such as "lung C", is also referred to as a scan target site. The scan target site may be set as one or more sites such as "lung" or "lung and liver", or may be set in a comprehensive unit such as "chest".

As shown in FIG. 2, the processing circuit 36 executes a preliminary scan and generates preliminary image data (step S1). The process of step S1 is, for example, as follows.

The processing circuit 36 reads a program corresponding to the scan control function 361 from the storage circuit 35 and executes it. The scan control function 361 is a function of operating each component of the gantry 10, the bed 20, and the console 30 at an appropriate timing according to a purpose to execute a scan. The processing circuit 36 scans the lung C of the subject P holding his / her breath by executing the scan control function 361, and collects preliminary projection data of the scan target site and its surroundings.

Here, the processing circuit 36 may perform the preliminary scan in two dimensions or in three dimensions. For example, when performing a two-dimensional preliminary scan, the processing circuit 36 moves the top plate 21 while irradiating X-rays from the X-ray tube 141 with the rotating frame 17 fixed, and moves the subject P in the body axis direction. Scan along. Then, the processing circuit 36 reads out a program corresponding to the image generation function 363 from the storage circuit 35 and executes it to perform image generation processing on the preliminary projection data and generate preliminary image data.

Further, for example, when performing a three-dimensional preliminary scan, the processing circuit 36 moves the top plate 21 while irradiating X-rays from the X-ray tube 141 in a state where the rotating frame 17 is rotated, and moves the subject P. Helical scan along the body axis. Specifically, when performing a three-dimensional preliminary scan, the processing circuit 36 operates each component of the gantry 10, the bed 20, and the console 30 as follows.

The processing circuit 36 controls the bed drive circuit 22 to move the top plate 21 on which the subject P is placed with respect to the gantry 10. At the same time, the processing circuit 36 supplies the tube voltage to the X-ray tube 141 by controlling the high voltage generation circuit 11, and rotates the rotating frame 17 by controlling the gantry drive circuit 13. The processing circuit 36 adjusts the opening degree and the position of the collimator 143 by controlling the collimator adjusting circuit 12. The processing circuit 36 collects preliminary projection data in and around the scan target portion by controlling the data acquisition circuit 16. The X-ray tube 141 is irradiated with X-rays having a lower dose than the main scan described later.

The processing circuit 36 reads a program corresponding to the preprocessing function 362 from the storage circuit 35 and executes it. The preprocessing function 362 is a function for correcting the projection data generated by the data acquisition circuit 16. This correction is, for example, logarithmic transformation, offset correction, sensitivity correction, beam hardening correction, and scattered ray correction. The processing circuit 36 applies these corrections to the preliminary projection data by the preprocessing function 362.

The processing circuit 36 reads a program corresponding to the image generation function 363 from the storage circuit 35 and executes it. The image generation function 363 includes a function of reconstructing the preliminary projection data and generating the preliminary image data. The processing circuit 36 generates preliminary image data of the scan target portion and its surroundings by executing the image generation function 363. The reconstruction method is, for example, a back projection method or a successive approximation method. Further, the back projection method is, for example, an FBP (Filtered Back Projection) method.

As shown in FIG. 2, the processing circuit 36 sets the scan target portion and the first scan range (step S2). The process of step S2 is, for example, as follows.

The processing circuit 36 reads a program corresponding to the acquisition function 364 from the storage circuit 35 and executes it. The acquisition function 364 is a function for acquiring a scan target portion and a first scan range. For example, the processing circuit 36 sets the scan target portion and the first scan range by executing the acquisition function 364.

For example, the processing circuit 36 sets the scan target portion by receiving an input operation of the scan target portion from the user via the input circuit 31. Further, for example, the processing circuit 36 accesses a server that manages HIS (Hospital Information Systems) and RIS (Radiology Information Systems) via a network, and sets a scan target portion by referring to inspection reservation information. do. As an example, the processing circuit 36 sets the lung C of the subject P as the scan target site.

Further, for example, the processing circuit 36 sets the first scan range based on the preliminary projection data collected by the preliminary scan. As an example, the processing circuit 36 first generates preliminary image data from preliminary projection data collected by a two-dimensional or three-dimensional preliminary scan. Next, the processing circuit 36 performs display processing on the generated preliminary image data to generate a preliminary image. Next, the processing circuit 36 displays the preliminary image on the display 32, and accepts the input operation of the first scan range from the user who has referred to the preliminary image. For example, as shown in FIG. 3, the user inputs the region A1 including the lung C in the preliminary image Im as the first scan range. Then, the processing circuit 36 sets the area A1 based on the input operation of the user as the first scan range.

The first scan range is not limited to the case where the user inputs it, and the processing circuit 36 can also set it. For example, the processing circuit 36 sets a range corresponding to the scan target portion in the preliminary image data as the first scan range. As an example, the processing circuit 36 sets the first scan range based on the anatomical feature points of the scan target portion extracted from the preliminary image data or the contour of the scan target portion drawn in the preliminary image data. Alternatively, the processing circuit 36 sets the first scan range based on the luminance of at least a part of the pixels of the preliminary projection data.

Although the case where the processing circuit 36 sets the scan target portion and the first scan range has been described, the embodiment is not limited to this. For example, the processing circuit 36 may acquire at least one of the scan target portion and the first scan range from an external device. Here, the external device is, for example, a workstation connected to the X-ray CT device 1 via a network.

As an example, first, the processing circuit 36 sets the scan target portion by receiving an input operation of the scan target portion from the user via the input circuit 31. Next, the processing circuit 36 transmits the scan target portion and the preliminary image data to the external device via the network. Next, the external device sets the range corresponding to the scan target portion in the preliminary image data as the first scan range. Then, the processing circuit 36 acquires the first scan range from the external device.

To give another example, first, the external device sets the scan target portion by accepting an input operation of the scan target portion from the user. Further, the external device acquires preliminary image data from the processing circuit 36 via the network. Next, the external device sets the range corresponding to the scan target portion in the preliminary image data as the first scan range. Then, the processing circuit 36 acquires the scan target portion and the first scan range from the external device.

As shown in FIG. 2, the processing circuit 36 estimates the position of the scan target portion while scanning the scan target portion, and changes the first scan range to the second scan range (step S3). The process of step S3 is, for example, as follows.

The processing circuit 36 reads a program corresponding to the scan control function 361 from the storage circuit 35 and executes it. The processing circuit 36 helical scans the lung C of the subject P holding his breath and collects the projection data of the first scan range. The helical scan performed in step S3 is also referred to as a main scan.

The processing circuit 36 reads a program corresponding to the preprocessing function 362 from the storage circuit 35 and executes it. The processing circuit 36 corrects the projection data by the preprocessing function 362.

The processing circuit 36 reads a program corresponding to the image generation function 363 from the storage circuit 35 and executes it. The image generation function 363 includes a function of generating partial image data by reconstructing the projection data of the scan target portion collected by the scan while the scan target portion is being scanned. By executing the image generation function 363, the processing circuit 36 reconstructs the projection data collected by the scan executed in step S3 one by one, and generates partial image data. The partial image data may be reconstructed slice data or volume data based on a plurality of slices. The reconstruction method is, for example, a back projection method or a successive approximation method. However, the reconstruction method used in step S3 is preferably one that can quickly generate partial image data.

The processing circuit 36 reads a program corresponding to the estimation function 365 from the storage circuit 35 and executes it. The estimation function 365 is a function of estimating the position of the scan target portion based on the projection data of the scan target portion collected by the scan while the scan target portion is being scanned. For example, the processing circuit 36 estimates the position of the scan target portion based on the partial image data by executing the estimation function 365. Specifically, the processing circuit 36 collates the partial image data with the preliminary image data while the scan target portion is being scanned, and estimates the position of the scan target portion.

More specifically, the processing circuit 36 collates the anatomical feature points extracted from the partial image data with the anatomical feature points extracted from the preliminary image data, and estimates the position of the end of the scan target site in the scan direction. do. The anatomical feature points extracted from the partial image data are three-dimensionally distributed on the three-dimensional partial image data and two-dimensionally distributed on the two-dimensional partial image data. Further, the anatomical feature points extracted from the preliminary image data are three-dimensionally distributed on the three-dimensional preliminary image data and two-dimensionally distributed on the two-dimensional preliminary image data. This estimation result is updated as the partial image data is updated by reconstructing the projection data collected by the scan executed in step S3 one by one.

Alternatively, since the shape of the contour of the lung C does not depend much on the inspiratory volume of the subject P, the processing circuit 36 estimates the position of the terminal based on the contour of the lung C. For example, the processing circuit 36 collates the contour of the scan target portion extracted from the partial image data with the contour of the scan target portion extracted from the preliminary image data, and estimates the position of the end of the scan target portion in the scan direction. For example, in the processing circuit 36, since the contour and volume of the upper part of the lung C do not depend much on the inspiratory amount of the subject P, the upper contour of the lung C extracted from the partial image data is extracted from the preliminary image data of the lung C. Align with the contour of the upper part of the lung C and match these two contours to estimate the position of the end of lung C in the scanning direction. This estimation result is updated as the partial image data is updated by reconstructing the projection data collected by the scan performed in step S3 one by one. The contour referred to here includes a two-dimensional contour and a three-dimensional contour.

Alternatively, the processing circuit 36 estimates the position of the end of the scan target portion in the scan direction based on the ratio of the area of the scan target portion extracted from the partial image data to the area of the scan target portion extracted from the preliminary image data. .. This estimation result is updated as the partial image data is updated by reconstructing the projection data collected by the scan performed in step S3 one by one.

Further, the processing circuit 36, together with the estimation of the position of the scan target portion described above, terminates the scan target portion in the scan direction when the scan target portion is visualized in the partial image data at the end of the first scan range. Is estimated to be outside the first scan range. For example, when the lung C which is the scan target site is visualized in the partial image data E1 at the end of the first scan range as shown in FIG. 4, the processing circuit 36 is the body of the lung C as shown in FIG. It is presumed that the axial termination is outside the first scan range (region A1). When the inspiratory volume of the subject P in step S3 is larger than the inspiratory volume of the subject P in step S1, the volume of the lung C in step S3 is larger than the volume of the lung C in step S1. Therefore, the axial termination of lung C may be located outside the first scan range.

In this case, the processing circuit 36 compares the preliminary image data at the end of the first scan range with the partial image data at the end of the first scan range, and the end in the scan direction of the scan target portion is the first. It may be presumed to be outside the scan range. That is, when the processing circuit 36 does not visualize the lung C in the preliminary image data at the end of the first scan range and the lung C is visualized in the partial image data at the end of the first scan range, both of them. By comparing, it can be estimated that the end of the scan target portion in the scan direction is outside the first scan range.

The processing circuit 36 reads a program corresponding to the change function 366 from the storage circuit 35 and executes it. The processing circuit 36 changes the first scan range to the second scan range based on the estimated position of the scan target portion. For example, the processing circuit 36 collates the anatomical feature points extracted from the partial image data with the anatomical feature points extracted from the preliminary image data, or the contour of the scan target portion extracted from the partial image data is the preliminary image data. Based on the result of collating with the contour of the scan target portion extracted from, the volume of the second scan range, that is, the position of the end of the second scan range is estimated. Next, the processing circuit 36 determines the volume of the second scan range, that is, the position of the end of the second scan range, based on the scan target portion depicted in the partial image data at the end of the first scan range. decide. Then, while the scan target portion is being scanned, the processing circuit 36 sets the first scan range based on the position of the scan target portion estimated by the estimation function 365, and the second scan range including the entire scan target portion. Change to. The processing circuit 36 sets the area A2 as the second scan range, for example, as shown in FIG. Region A2 includes the entire lung C, which is the site to be scanned.

The processing circuit 36 reads a program corresponding to the notification function 367 from the storage circuit 35 and executes it. The processing circuit 36 notifies that the first scan range has been changed to the second scan range. For example, the processing circuit 36 notifies that the change function 366 has changed the first scan range to the second scan range wider than the first scan range by executing the notification function 367. The method for notifying that the first scan range has been changed to the second scan range is not particularly limited. By executing the notification function 367, the processing circuit 36 may display, for example, a message or an icon indicating that the first scan range has been changed to the second scan range on the display 32. Alternatively, the processing circuit 36 may emit a sound notifying that the first scan range has been changed to the second scan range by executing the notification function 367.

As shown in FIG. 2, the processing circuit 36 determines whether or not the scan of the entire second scan range is completed by executing the scan control function 361 (step S4). For example, when the lung C, which is the scan target site, is not visualized in the partial image data E2 at the end of the second scan range as shown in FIG. 7, the processing circuit 36 completes the scan of the entire second scan range. It is determined that it has been done. When it is determined that the scan of the entire second scan range is completed (step S4 affirmative), the processing circuit 36 ends the processing. For example, when the lung C, which is the scan target site, is visualized in the partial image data at the end of the second scan range, the processing circuit 36 determines that the scan of the entire second scan range has not been completed. When the processing circuit 36 determines that the scanning of the entire second scanning range has not been completed (denial in step S4), the processing circuit 36 returns the processing to step S3. In this case, the second scan range in step S4 is regarded as the first scan range in step S3.

The X-ray CT apparatus 1 according to the embodiment has been described above. As described above, the X-ray CT apparatus 1 estimates the position of the scan target part based on the projection data of the scan target part collected by the scan while the scan target part is being scanned, and the estimated scan. The first scan range is changed to the second scan range including the entire scan target site based on the position of the target site. Therefore, the X-ray CT apparatus 1 can reliably scan the entire scan target portion with a single scan. Further, the X-ray CT apparatus 1 can prevent the CT image data of the scan target portion from including the seam. Further, since the X-ray CT apparatus 1 does not need to additionally scan the scan target portion and does not scan an unnecessary range, the dose of X-rays to be irradiated to the subject P can be reduced.

Further, the X-ray CT apparatus 1 described above estimates the position of the end of the second scan range based on the preliminary image data and the partial image data. Then, the X-ray CT apparatus 1 changes the first scan range to the second scan range including the entire scan target portion based on the estimation result. Therefore, the X-ray CT apparatus 1 can quickly change the first scan range to the second scan range having the smallest possible volume, and can improve the throughput. This process performed by the X-ray CT apparatus 1 is particularly effective when the scan of the scan target portion is completed in a short time.

Hereinafter, a modified example of the above-described embodiment will be described.

In step S3 of FIG. 2, the processing circuit 36 may perform the following processing instead of the above-mentioned processing. By executing the estimation function 365, the processing circuit 36 may estimate the position of the end of the scan target portion in the scan direction based on the anatomical feature points extracted from the partial image data. Alternatively, the processing circuit 36 may execute the estimation function 365, so that the processing circuit 36 estimates the position of the end of the scan target portion in the scan direction based on the contour of the scan target portion extracted from the partial image data. good. In these cases, the preliminary image data is used only for setting the first scan range performed in step S2 of FIG.

Next, the processing circuit 36 is extracted from the terminal position or the partial image data in the scanning direction of the scan target part estimated based on the anatomical feature points extracted from the partial image data by executing the change function 366. The volume of the second scan range, that is, the position of the end of the second scan range is estimated based on the position of the end of the scan target part in the scan direction estimated based on the contour of the scan target part. Then, while the scan target portion is being scanned, the processing circuit 36 sets the first scan range based on the position of the scan target portion estimated by the estimation function 365, and the second scan range including the entire scan target portion. Change to.

The processing circuit 36 does not have to execute the processing of step S1 of FIG. That is, the processing circuit 36 does not have to execute the preliminary scan and generate the preliminary image data. In this case, the processing circuit 36 sets the scan target portion and the first scan range by a predetermined method in step S2 of FIG. Further, the processing circuit 36 estimates the position of the end of the scan target portion in the scan direction based on the anatomical feature points extracted from the partial image data by executing the estimation function 365 in step S3 of FIG. .. Alternatively, the processing circuit 36 executes the estimation function 365 in step S3 of FIG. 2, and the processing circuit 36 terminates in the scanning direction of the scanning target portion based on the contour of the scanning target portion extracted from the partial image data. Estimate the position of.

By executing the estimation function 365 in step S3 of FIG. 2, the processing circuit 36 scans the target portion based on the brightness of at least a part of the pixels of the projected data of the scan target portion instead of the partial image data of the scan target portion. The position of the site may be estimated. For example, the processing circuit 36 has the position of the scan target portion in the cross section of the subject P based on the meandering method of the region having the brightness corresponding to the scan target portion in the projection data collected in step S3 of FIG. To estimate. Further, the processing circuit 36 is based on the change in the width in the channel direction in the view direction of the region having the brightness corresponding to the scan target portion in the projection data collected in step S3 of FIG. 2, and the coronal plane of the subject P. And estimate the position of the scan target site on the sagittal plane.

The processing circuit 36 may set the first scan range based on the preliminary projection data instead of the preliminary image data by executing the acquisition function 364 in step S2 of FIG. For example, the processing circuit 36 is based on the meandering method of the region having the brightness corresponding to the scan target portion in the preliminary projection data collected in step S1 of FIG. 2, the scan target portion in the cross section of the subject P. Identify the location. Further, the processing circuit 36 coronal plane of the subject P based on the change in the width in the channel direction in the view direction of the region having the brightness corresponding to the scan target portion in the preliminary projection data collected in step S1 of FIG. Identify the location of the scan target site on the surface and sagittal plane. Then, in step S2 of FIG. 2, the processing circuit 36 sets the first scan range including the entire scan target portion by executing the acquisition function 364.

By executing the estimation function 365 in step S3 of FIG. 2, the processing circuit 36 performs projection data of the scan target portion instead of collating the partial image data with the preliminary image data while the scan target portion is being scanned. May be collated with the preliminary projection data to estimate the position of the scan target site. As a result, the processing circuit 36 does not need to execute the image generation function 363 and reconstruct the projection data, so that the position of the scan target portion can be quickly estimated.

When the processing circuit 36 executes the change function 366 and the estimation function 365 estimates that all of the scan target parts are within the first scan range, the first scan range is set to be larger than the first scan range. It may be changed to a narrow second scan range. Even in this case, the second scan range includes the entire scan target portion. Alternatively, when the processing circuit 36 executes the change function 366 and the estimation function 365 estimates that all of the scan target parts are within the first scan range, the first scan range is set to the first scan range. It may be changed to a second scan range having the same position and volume as. Therefore, the processing circuit 36 can reduce the dose of X-rays to irradiate the subject P while reliably scanning the entire scan target portion with one scan.

By executing the scan control function 361, the processing circuit 36 reduces the moving speed of the top plate 21 to reduce the helical pitch when the volume of the unscanned range of the second scan range is equal to or less than the threshold value. It may be lowered. Therefore, the processing circuit 36 can surely end the scan at the end of the second scan range. Further, by executing the scan control function 361, the processing circuit 36 scans the dose of X-rays applied to the subject P in the second scan range in accordance with the decrease in the moving speed of the top plate 21. The tube current of the X-ray tube 141 may be controlled so that the volume in the non-existing range is the same as the case where the volume is larger than the threshold value. Therefore, the processing circuit 36 can suppress an increase in the dose applied to the subject P due to the decrease in the moving speed of the top plate 21.

By executing the scan control function 361, the processing circuit 36 adjusts the opening degree and the position of the collimator 143 when the volume of the unscanned range in the second scan range is equal to or less than the threshold value, and the second scan range is executed. X-rays may not be emitted outside the scan range. Such control of the collimator 143 is also referred to as an active collimator. As a result, the processing circuit 36 can prevent the dose of X-rays applied to the subject P from being unnecessarily increased.

In the above-described embodiment, the case where the X-ray CT apparatus 1 scans the lung C, which is the scan target site, from the head side to the abdomen side of the subject P has been described as an example, but the present invention is not limited to this. The X-ray CT apparatus 1 may scan the lung C, which is the scan target site, from the abdominal side to the head side of the subject P. However, the lung C swells toward the abdomen side of the subject P when the subject P inhales. Therefore, when the scan target site is the lung C, the X-ray CT apparatus 1 preferably scans the lung C from the head side to the abdomen side of the subject P. Further, the above-described embodiment can also be applied to the case where the scan target portion is repeatedly scanned. Furthermore, the above-described embodiment can also be applied when the scan target site is other than lung C.

Further, in the above-described embodiment, a case where the position of the scan target portion is estimated and the first scan range is changed to the second scan range based on the estimated position has been described. However, the embodiment is not limited to this. For example, the processing circuit 36 can change the first scan range to the second scan range based on the slices reconstructed in real time from the collected projection data while the scan target portion is being scanned. ..

Hereinafter, the case where the scan range is changed based on the slice will be described by taking the case where the scan target site is lung C as an example. First, the processing circuit 36 acquires the scan target portion and the first scan range, and starts scanning. Here, the processing circuit 36 reconstructs slices in real time based on the projected data collected while lung C is being scanned. Further, the processing circuit 36 determines in real time whether or not the reconstructed slice contains lung C. For example, the processing circuit 36 determines whether the slice contains lung C based on the fact that lung C is filled with air and the CT value of air is significantly smaller than that of body tissue. be able to. The processing circuit 36 may reduce the helical pitch after the volume of the unscanned range of the first scan range becomes equal to or less than the threshold value.

Then, when it is determined that the reconstructed slice does not contain lung C, the processing circuit 36 terminates the first scan range and the second scan ending at the position where the slice no longer contains lung C. Change to range. That is, the processing circuit 36 ends the scan when the slices reconstructed in real time no longer contain lung C. As a result, the processing circuit 36 can reduce the exposure dose of the subject P and reliably scan the lung C with a single scan.

Further, in the above-described embodiment, the case of scanning to the end of the scan target portion has been described, but the embodiment is not limited to this. For example, the processing circuit 36 may further perform a predetermined volume integral scan from the end of the scan target portion. The predetermined volume may be a condition set by the user before the start of the main scan, or may be a fixed condition.

For example, the predetermined volume is set using the length from the end of the scan target portion. In this case, the subject P is scanned three-dimensionally from the end of the scan target portion by the set "length". That is, a predetermined volume can be set by setting the "length". As an example, the predetermined volume is set as "3 cm from the end of lung C".

Further, for example, a predetermined volume is set by using a portion around the scan target portion. Here, when the site to be scanned is lung C, examples of the peripheral site include liver L. As an example, a predetermined volume is set as "up to a position where the cross-sectional area of the liver becomes a predetermined area". In this case, the subject P is scanned in three dimensions from the end of the scan target portion to the set "position". That is, a predetermined volume can be set by setting the "position".

Here, a case where scanning for a predetermined volume is further performed from the end of the scan target portion will be described with reference to FIGS. 8 and 9. 8 and 9 are diagrams for explaining a case where scanning for a predetermined volume is further performed.

First, the processing circuit 36 acquires the first scan range. For example, the processing circuit 36 sets the position from the upper end of the lung C to the position where the cross-sectional area of the liver L becomes a predetermined area as the first scan range in the preliminary image data collected in three dimensions. Next, the processing circuit 36 starts scanning and reconstructs the slice in real time. Here, when the slice contains the liver L, the processing circuit 36 acquires the cross-sectional area of the liver L in the slice in real time. For example, the processing circuit 36 acquires the area of the liver L in the partial image data E3, as shown in FIG. The processing circuit 36 may reduce the helical pitch after the volume of the unscanned range of the first scan range becomes equal to or less than the threshold value.

Then, the processing circuit 36 changes the first scan range to the second scan range ending at the position where the cross-sectional area of the liver L becomes a predetermined area. Specifically, as shown in FIG. 9, the processing circuit 36 sets the position of the end of the second scan range as a predetermined position in the body axis direction of the liver L. That is, the processing circuit 36 changes the first scan range from the position where the scan of the lung C is completed to the second scan range in which the predetermined volume integral is increased, and performs the predetermined volume integral scan from the end of the lung C. The scan ends at that point. As a result, the processing circuit 36 can reduce the exposure dose of the subject P and reliably scan the lung C and a predetermined volume at one time.

The above-mentioned processors include, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array. (Field Programmable Gate Array: FPGA). Further, the programmable logic device (PLD) is, for example, a simple programmable logic device (Simple Programmable Logic Device: SPLD) or a compound programmable logic device (Complex Programmable Logic Device: CPLD).

In the above-described embodiment, the high voltage generation circuit 11, the collimator adjustment circuit 12, the gantry drive circuit 13, the data acquisition circuit 16, the sleeper drive circuit 22, and the processing circuit 36 read out and execute the program stored in the storage circuit 35. By doing so, the function was realized, but the function is not limited to this. Instead of storing the program in the storage circuit 35, the program may be directly incorporated in each of these circuits. In this case, these circuits realize their functions by directly reading and executing the embedded program.

Each circuit shown in FIG. 1 may be appropriately distributed or integrated. For example, the processing circuit 36 is a scan control circuit that executes the functions of the scan control function 361, the preprocessing function 362, the image generation function 363, the acquisition function 364, the estimation function 365, the change function 366, the notification function 367, and the control function 368. , Preprocessing circuit, image generation circuit, acquisition circuit, estimation circuit, change circuit, notification circuit and control circuit may be distributed. Further, for example, the high voltage generation circuit 11, the collimator adjustment circuit 12, the gantry drive circuit 13, the data acquisition circuit 16, the sleeper drive circuit 22, and the processing circuit 36 may be arbitrarily integrated.

According to at least one embodiment described above, the scan target portion can be reliably scanned with a single scan.

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 embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

364 Acquisition function 365 Estimate function 366 Change function

Claims (21)

The acquisition unit that acquires the scan target part and the first scan range,
An image generation unit that generates partial image data by reconstructing projection data related to the scan target portion collected by the scan while the scan target portion is being scanned.
While the scan target site is being scanned, an estimation unit that estimates the position of the scan target site based on the partial image data, and an estimation unit.
While the scan target site is being scanned, the first scan range is changed to a second scan range including all of the scan target sites based on the position of the scan target site estimated by the estimation unit . Change part and
Equipped with
The acquisition unit acquires the first scan range based on the preliminary projection data collected by the preliminary scan.
The image generation unit generates preliminary image data from the preliminary projection data,
The estimation unit is based on the ratio of the area of the scan target portion extracted from the partial image data to the area of the scan target portion extracted from the preliminary image data while the scan target portion is being scanned. , An X-ray CT apparatus that estimates the position of the end of the scan target area in the scan direction . The acquisition unit that acquires the scan target part and the first scan range,
An estimation unit that estimates the position of the scan target portion based on the brightness of at least a part of the pixels of the projection data of the scan target portion collected by the scan while the scan target portion is being scanned.
While the scan target site is being scanned, the first scan range is changed to a second scan range including all of the scan target sites based on the position of the scan target site estimated by the estimation unit. Change part and
X-ray CT apparatus. The acquisition unit that acquires the scan target part and the first scan range,
While the scan target site is being scanned, an estimation unit that estimates the position of the scan target site based on the projection data of the scan target site collected by the scan, and an estimation unit.
While the scan target site is being scanned, the first scan range is changed to a second scan range including all of the scan target sites based on the position of the scan target site estimated by the estimation unit. Change part and
Equipped with
The acquisition unit acquires the first scan range based on the preliminary projection data collected by the preliminary scan.
The estimation unit is an X-ray CT apparatus that estimates the position of the scan target portion by collating the projection data of the scan target portion with the preliminary projection data while the scan target portion is being scanned. The acquisition unit that acquires the scan target part and the first scan range,
While the scan target site is being scanned, the first scan range is determined from the position where the scan of the scan target site is completed, based on the projection data of the scan target site collected by the scan. The change part that changes to the second scan range with the larger volume integral of
X-ray CT apparatus. Further provided with an estimation unit that estimates the position of the scan target site based on the projection data of the scan target site collected by the scan while the scan target site is being scanned.
While the scan target site is being scanned, the change unit includes the second scan range including the entire scan target site based on the position of the scan target site estimated by the estimation unit. The X-ray CT apparatus according to claim 4 , wherein the X-ray CT apparatus is changed to the scan range of the above. Further provided with an image generation unit that generates partial image data by reconstructing the projection data related to the scan target portion collected by the scan while the scan target portion is being scanned.
The X-ray CT apparatus according to claim 5 , wherein the estimation unit estimates the position of the scan target portion based on the partial image data. When the scan target portion is visualized in the partial image data at the end of the first scan range, the estimation unit has the end of the scan target portion in the scan direction outside the first scan range. The X-ray CT apparatus according to claim 1 or 6 . The X-ray CT apparatus according to claim 6 or 7 , wherein the estimation unit estimates the position of the end of the scan target site in the scan direction based on the anatomical feature points extracted from the partial image data. The X-ray CT apparatus according to claim 6 or 7 , wherein the estimation unit estimates the position of the end of the scan target portion in the scan direction based on the contour of the scan target portion extracted from the partial image data. .. The acquisition unit acquires the first scan range based on the preliminary projection data collected by the preliminary scan.
The image generation unit generates preliminary image data from the preliminary projection data,
The sixth or seventh aspect of the present invention, wherein the estimation unit collates the partial image data with the preliminary image data and estimates the position of the scan target portion while the scan target portion is being scanned. X-ray CT device. The estimation unit collates the anatomical feature points extracted from the partial image data with the anatomical feature points extracted from the preliminary image data, and estimates the position of the end of the scan target site in the scan direction. Item 10. The X-ray CT apparatus according to Item 10. The estimation unit collates the contour of the scan target portion extracted from the partial image data with the contour of the scan target portion extracted from the preliminary image data, and estimates the position of the end of the scan target portion in the scan direction. , The X-ray CT apparatus according to claim 10 . The estimation unit is based on the ratio of the area of the scan target portion extracted from the partial image data to the area of the scan target portion extracted from the preliminary image data, and the position of the end of the scan target portion in the scan direction. 10. The X-ray CT apparatus according to claim 10 . The X-ray CT apparatus according to claim 5 , wherein the estimation unit estimates the position of the scan target portion based on the brightness of at least a part of the pixels of the projection data of the scan target portion. The acquisition unit acquires the first scan range based on the preliminary projection data collected by the preliminary scan.
The X according to claim 5 , wherein the estimation unit collates the projection data of the scan target portion with the preliminary projection data while the scan target portion is being scanned, and estimates the position of the scan target portion. Line CT device. The X-ray CT apparatus according to any one of claims 1 to 15 , further comprising a notification unit for notifying that the change unit has changed the first scan range to the second scan range. The X-ray CT apparatus according to claim 16 , wherein the notification unit notifies that the change unit has changed the first scan range to the second scan range wider than the first scan range. When the estimation unit estimates that all of the scan target parts are within the first scan range, the change unit sets the first scan range to be narrower than the first scan range. The X-ray CT apparatus according to any one of claims 1 to 3 or claims 5 to 15 , which is changed to a scan range. Claim 1 to claim 1, further comprising a scan control unit that lowers the helical pitch by lowering the moving speed of the top plate when the volume of the unscanned range in the second scan range is equal to or less than the threshold value. The X-ray CT apparatus according to any one of 18 . In the scan control unit, the volume of the unscanned range of the second scan range in which the dose of X-rays applied to the subject is larger than the threshold value in accordance with the decrease in the moving speed of the top plate. The X-ray CT apparatus according to claim 19 , wherein the tube current of the X-ray tube is controlled so as to have the same dose as in the case. The acquisition unit that acquires the scan target part and the first scan range,
An image generation unit that generates partial image data by reconstructing projection data related to the scan target portion collected by the scan while the scan target portion is being scanned.
While the scan target site is being scanned, an estimation unit that estimates the position of the scan target site based on the partial image data, and an estimation unit.
While the scan target site is being scanned, the first scan range is changed to a second scan range including all of the scan target sites based on the position of the scan target site estimated by the estimation unit. Change part and
X-ray CT apparatus.

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