Patent Description:
A CT device is known as a medical device that noninvasively images a subject body. CT devices can capture images of a portion to be imaged in a short period of time, and therefore have become widespread in hospitals and other medical facilities.

Examples of such CT devices are shown in <CIT>, which shows a gantry including an X-ray tube, a controller and a table on which a subject body can lie. Another example is shown in <CIT>.

When performing an examination of a subject body, an operator lays the subject body on a table so that the subject body lies on the table in a posture (body position) suitable for the examination. For example, when imaging the head of the subject body, the operator generally lays the subject body on a table in a supine position.

In the supine position, the subject body desirably lies on a table with their face facing directly upward. However, if facing the face of the subject body directly upward is not possible because the subject body is elderly or suffering from illness, the face of the subject body may face, for example, obliquely upward.

In this case, securing the head of the subject body using a head folder or the like so that the face of the subject body faces directly upward can be considered (see, for example, <CIT> mentioned above. However, for a subject body where there is difficulty in directing his/her face directly upward, forcibly causing the face to face directly upward using the head folder may impose a heavy burden on the body of the subject body. Therefore, in general, scanning is performed in a state where the face of the subject body faces obliquely upward. For example, when a scout scan is executed, a scout image is acquired in a state where the face of the subject body faces obliquely upward.

The scout image is used for setting the scan range of the subject body, and the operator sets the scan range of the subject body with reference to the scout image. In addition, in recent years, a technique of executing segmentation of a scout image and automatically setting a scan range of a subject body based on the result of the segmentation, and a technique of specifying an organ having high sensitivity to radiation based on a result of the segmentation of a scout image and selectively reducing exposure to the specified organ have also been researched and developed.

However, since imaging in the supine position is based on the assumption that the face of the subject body faces directly upward, if a scout image is acquired in a state where the face of the subject body faces obliquely upward, there is a problem in that the accuracy of segmentation decreases, and the automatically set scan range deviates from a desired range or the specified region of the organ deviates from the region where the organ actually exists. In the example described above, a problem was described for the case of imaging a head of a subject body, but the same problem exists for imaging portions of the subject body other than the head.

Here, providing technology enabling acquiring substantially the same image as the image acquired when the portion to be imaged is facing the desired direction even if the subject body is scanned while the portion to be imaged can not face the desired direction is desirable.

A first aspect of the present invention is a medical device, including:.

In addition, a second aspect of the present invention is a method of scanning, comprising:.

In addition, a third aspect of the present invention is a storage medium readable by a computer in a non-transitory manner storing one or more instructions executable by one or more processors, wherein.

In the present invention, the direction of the portion to be imaged is obtained, and the position of the X-ray tube is determined based on the direction of the portion to be imaged. Thereby enabling acquiring substantially the same image as the image acquired when the portion to be imaged is facing the desired direction even if the subject body is scanned while the portion to be imaged can not face the desired direction.

An embodiment for carrying out the invention will be described below, but the present invention is not limited to the following embodiment. <FIG> is a perspective view of a CT device <NUM> of Embodiment <NUM>. <FIG> is a block diagram of the CT device <NUM>.

The CT device <NUM> includes a gantry <NUM> and a table <NUM>. The gantry <NUM> and the table <NUM> are installed in a scan room <NUM>.

The gantry <NUM> has an opening <NUM> through which a subject body <NUM> is transported to scan the subject body <NUM>.

The gantry <NUM> is equipped with an X-ray tube <NUM>, a filter part <NUM>, a front collimator <NUM>, and an X-ray detector <NUM>.

The X-ray tube <NUM> generates X-rays when a prescribed voltage is applied to the cathode-anode tube. The X-ray tube <NUM> is configured to be rotatable on a path centered on the rotation axis within the XY plane. Here, the Z direction represents the body axis direction, the Y direction represents the vertical direction (the height direction of the table <NUM>), and the X direction represents the direction perpendicular to the Z and Y directions. An X-ray tube compatible with a rapid kV switching system capable of switching the tube voltage may be provided as the X-ray tube <NUM>. Moreover, although the CT device <NUM> includes one X-ray tube <NUM> in Embodiment <NUM>, two X-ray tubes may be included.

The filter part <NUM> includes, for example, a flat plate filter and/or a bow-tie filter.

The front collimator <NUM> is a component that narrows the X-ray irradiation range so that X-rays are not emitted in unwanted areas.

The X-ray detector <NUM> includes a plurality of detector elements <NUM>. A plurality of detector elements <NUM> detect an X-ray beam <NUM> that is irradiated from the X-ray tube <NUM> and passes through the subject body <NUM>, such as a patient. Thus, the X-ray detector <NUM> can acquire projection data for each view.

The projection data detected by the X-ray detector <NUM> is collected by a DAS <NUM>. The DAS <NUM> performs prescribed processing, including sampling and digital conversion, on the collected projection data. The processed projection data is transmitted to a computer <NUM>. Data from the DAS <NUM> may be stored in a storing device <NUM> by the computer <NUM>. The storing device <NUM> includes one or more storage media that store programs as well as instructions to be executed by the processor. The storage medium can be, for example, one or more non-transitory, computer-readable storage media. The storing device <NUM> may include, for example, hard disk drives, floppy disk drives, compact disc read/write (CD-R/W) drives, digital versatile disk (DVD) drives, flash drives, and/or solid state storage drives.

The computer <NUM> includes one or a plurality of processors. The computer <NUM> uses one or a plurality of processors to output commands and parameters to the DAS <NUM>, X-ray controller <NUM>, and/or gantry motor controller <NUM>, to control system operations such as data acquisition and/or processing. In addition, the computer <NUM> uses one or more processors to execute signal processing, data processing, image processing, and the like in each step of the flow described below (see <FIG>, <FIG>, <FIG>, and <FIG>).

An operator console <NUM> is linked to the computer <NUM>. An operator can enter prescribed operator inputs related to the operation of the CT device <NUM> into the computer <NUM> by operating the operator console <NUM>. The computer <NUM> receives operator input, including commands and/or scan parameters, via the operator console <NUM> and controls system operation based on that operator input. The operator console <NUM> can include a keyboard (not shown) or touch screen for the operator to specify commands and/or scan parameters.

The X-ray controller <NUM> controls the X-ray tube <NUM> based on control signals from the computer <NUM>. In addition, a gantry motor controller <NUM> also controls the gantry motors to rotate structural elements such as the X-ray tube <NUM> and the X-ray detector <NUM> based on control signals from the computer <NUM>.

<FIG> illustrates only one operator console <NUM>, but two or more operator consoles may be linked to the computer <NUM>.

In addition, the CT device <NUM> may also allow a plurality of remotely located displays, printers, workstations, and/or similar devices to be linked via, for example, a wired and/or wireless network.

In an embodiment, for example, the CT device <NUM> may include or be linked to a Picture Archiving and Communication System (PACS) <NUM>. In a typical implementation, a PACS <NUM> may be linked to a remote system such as a radiology department information system, hospital information system, and/or internal or external network (not shown).

The computer <NUM> supplies commands to a table motor controller <NUM> to control the table <NUM>. The table motor controller <NUM> can control the table motor so as to move the table <NUM> based on the instructions received. For example, the table motor controller <NUM> can move the table <NUM> so that the subject body <NUM> is positioned appropriately for imaging.

As mentioned above, the DAS <NUM> samples and digitally converts the projection data acquired by the detector elements <NUM>. The image reconstruction unit <NUM> then reconstructs the image using the sampled and digitally converted data. The image reconstruction unit <NUM> includes one or a plurality of processors, which can perform the image reconstruction process. In <FIG>, the image reconstruction unit <NUM> is illustrated as a separate structural element from the computer <NUM>, but the image reconstruction unit <NUM> may form a part of the computer <NUM>. In addition, the computer <NUM> may also perform one or more functions of the image reconstruction unit <NUM>. Furthermore, the image reconstruction unit <NUM> may be located away from the CT system <NUM> and operatively connected to the CT device <NUM> using a wired or wireless network. The computer <NUM> and image reconstruction unit <NUM> function as image generation devices.

The image reconstruction unit <NUM> can store the reconstructed image in the storing device <NUM>. The image reconstruction unit <NUM> may also transmit the reconstructed image to the computer <NUM>. The computer <NUM> can transmit the reconstructed image and/or patient information to a display device <NUM> communicatively linked to the computer <NUM> and/or image reconstruction unit <NUM>.

The various methods and processes described in the present specification can be stored as executable instructions on a non-transitory storage medium within the CT device <NUM>. The executable instructions may be stored on a single storage medium or distributed across a plurality of storage media. One or more processors provided in the CT device <NUM> execute the various methods, steps, and processes described in the present specifications in accordance with instructions stored on a storage medium.

A camera <NUM> is provided on a ceiling <NUM> of the scan room <NUM> as an optical image acquisition unit for acquiring an optical image in the scan room. Any device can be used as the optical image acquisition unit as long as it can image the surface of a subject such as a subject body. For example, a camera that uses visible light for imaging the subject, a camera that uses infrared for imaging the subject, or a depth sensor that uses infrared to acquire depth data of the subject and performs imaging of the surface of the subject based on the depth data, can be used as the optical image acquisition unit. Also, the optical image acquired by the optical image acquisition unit may be a 3D image or a 2D image. Furthermore, the optical image acquisition unit may acquire the optical image as a still image or as video.

The CT device <NUM> is configured as described above. A flow of imaging a subject body using the CT device of Embodiment <NUM> will be described below. In the following example, in order to clarify the effect of Embodiment <NUM>, first, a flow when examining a subject body using a general method will be described. Furthermore, after clarifying the problems of the general method, the flow of Embodiment <NUM> will be described.

<FIG> is a diagram illustrating an example of the CT device operation flow when a subject body is examined using a general method.

At step ST1, the operator lays the subject body <NUM> (for example, a patient) on the table <NUM>.

<FIG> is a diagram illustrating the subject body <NUM> lying on the table <NUM>.

A front view of the gantry <NUM> is shown in the upper part of <FIG>, and a top view of the gantry <NUM> and of the table <NUM> is shown in the lower part of <FIG>.

The table <NUM> has a cradle on which the subject body <NUM> can lie. The cradle is configured so as to be movable in the axial direction (z direction). Note that the front view of the gantry <NUM> on the upper side of <FIG> illustrates the head 112a of the subject body <NUM> with respect to the opening <NUM> of the gantry <NUM> in the XY plane. Here, the imaging portion is assumed to be the head 112a.

At step ST2, the operator establishes a scan plan for the scout scan.

<FIG> is an explanatory diagram of an example of a scan plan for a scout scan.

<FIG> includes an item <NUM> required in the scout scan plan and scan plans <NUM> and <NUM> set for that item. In <FIG>, "Start", "End", "kV", "mA", and "Scout Plane" are shown as items <NUM> of the scout scan plan. "Start" is the scan start position, "End" is the scan end position, "kV" is the tube voltage, "mA" is the tube current, and "Scout Plane" indicates the position of the X-ray tube <NUM> when the scout scan is executed. When the scout scan is ready, the process proceeds to step ST3.

At step ST3, a scout scan is executed according to scan plans <NUM> and <NUM>.

<FIG> is an explanatory diagram of a scout scan executed according to the scan plan <NUM>.

The gantry <NUM> includes an x-ray tube <NUM>. The X-ray tube <NUM> is configured to be rotatable on a path <NUM> centered on the rotation axis <NUM> within the XY plane. The rotation axis <NUM> may be set so as to coincide with the isocenter, or may be set as the rotation axis <NUM> at a position deviated from the isocenter.

In the scan plan <NUM>, "Scout Plane" is set to "<NUM>°". This indicates that the scout scan is executed with the X-ray tube <NUM> positioned at position P0 on the path <NUM>, just above the rotation axis <NUM>. Here, the angle of the X-ray tube <NUM> is assumed to be "<NUM>°" when the X-ray tube <NUM> is positioned at the position P0.

The scan plan <NUM> has the "Scout Plane" set to "<NUM>°". This indicates that the scout scan is performed with the x-ray tube <NUM> positioned at position P90, which is a clockwise rotation of <NUM>° from position P0 (angle <NUM>°) around the rotation axis <NUM> on the path <NUM>, as illustrated in <FIG>. This assumes that the angle of the X-ray tube <NUM> is "<NUM>°" when the X-ray tube <NUM> is positioned at a position rotated clockwise by <NUM>° from the angle of <NUM>°.

When performing a scout scan, first, a scout scan is executed according to the scan plan <NUM>. When performing the scout scan according to the scan plan <NUM>, the gantry motor controller <NUM> (see <FIG>) controls the gantry motor so that the X-ray tube <NUM> is positioned at angle <NUM>° (position P0), as illustrated in <FIG>. Furthermore, while moving the cradle in the Z-direction, the X-ray controller <NUM> controls the X-ray tube <NUM> so as to irradiate X-rays.

The X-ray detector <NUM> detects X-rays irradiated from the X-ray tube <NUM> and passed through the subject body <NUM>. The projection data detected by the X-ray detector <NUM> is collected by the DAS <NUM>. The DAS <NUM> performs prescribed processing, including sampling, digital conversion, and the like, on the acquired projection data and transmits the data to the computer <NUM> or image reconstruction unit <NUM>. On the computer <NUM> or image reconstruction unit <NUM>, a processor reconstructs the scout image based on the data obtained from the scan.

After executing a scout scan according to the scan plan <NUM>, a scout scan is executed according to the scan plan <NUM>.

When performing a scout scan according to the scan plan <NUM>, the gantry motor controller <NUM> controls the gantry motor so that the X-ray tube <NUM> rotates from a <NUM>° to <NUM>° angle, as illustrated in <FIG>. Therefore, the X-ray tube <NUM> is positioned at an angle of <NUM>° (position P90). Furthermore, while moving the cradle in the Z-direction, the X-ray tube <NUM> irradiates X-rays while positioned at an angle of <NUM>°.

Therefore, a scout image when the scan plan <NUM> is executed and a scout image when the scan plan <NUM> is executed can be obtained. <FIG> schematically shows the scout image <NUM> when the scan plan <NUM> is executed and a scout image <NUM> when the scan plan <NUM> is executed. The scout image <NUM> is an image obtained by irradiating X-rays from the X-ray tube <NUM> positioned at an angle of <NUM>° (position P0), and the scout image <NUM> is an image obtained by irradiating X-rays from the X-ray tube <NUM> positioned at an angle of <NUM>° (position P90). After executing the scout scan, the process proceeds to step ST4.

At step ST4, the operator makes a scan plan for a diagnostic scan. The operator, for example, refers to the scout images <NUM> and <NUM> (see <FIG>) to set the scan range for the diagnostic scan, which will be described later. The computer <NUM> also executes various processes based on the scout images <NUM> and <NUM>. For example, if Organ Dose Modulation (ODM) is used, that is a dose reduction technique used during diagnostic scans, the computer <NUM> executes processing to segment the scout images <NUM> and <NUM> and identify organs (for example, the eye) that are highly sensitive to radiation within the imaging portion that is the head 112a based on the segmentation results. When the preparation for executing the diagnostic scan is complete, processing proceeds to step ST5.

At step ST5, a diagnostic scan of the head 112a is performed. For example, when executing a diagnostic scan using ODM, a scan of the head 112a is executed so that the exposure of the radiation-sensitive eyes is selectively reduced.

The X-ray detector <NUM> detects X-rays irradiated from the X-ray tube <NUM> and that pass through the subject body <NUM>. The projection data detected by the X-ray detector <NUM> is collected by the DAS <NUM>. The DAS <NUM> performs prescribed processing, including sampling, digital conversion, and the like, on the acquired projection data and transmits the data to the computer <NUM> or image reconstruction unit <NUM>. In the computer <NUM> or image reconstruction unit <NUM>, a processor reconstructs a CT image necessary for diagnosis of the head 112a of the subject body <NUM> based on data obtained from the diagnostic scan. The operator can display the reconstructed CT image on the display device <NUM>. <FIG> is a diagram illustrating an example of the CT image <NUM> displayed on the display device <NUM>.

A doctor can interpret the CT images acquired according to the examination flow and perform a diagnosis.

In the above description, as illustrated in <FIG> and <FIG>, scanning is performed with the subject body <NUM> lying on the table <NUM> with the face of the subject facing upward. However, depending on the subject body <NUM>, facing directly upward may not be possible. For example, if facing the face of the subject body directly upward is not possible because the subject body <NUM> is elderly or suffering from illness, the face of the subject body <NUM> may face, for example, obliquely upward (see <FIG> and <FIG>).

<FIG> and <FIG> are diagrams illustrating examples in which the face of the subject body <NUM> cannot face directly upward.

A front view of the gantry <NUM> is illustrated in the upper part of <FIG>, and a top view of the gantry <NUM> and the table <NUM> are shown in the lower part of <FIG>. The subject body <NUM> lies on the table <NUM>. Note that the front view of the gantry <NUM> on the upper side of <FIG> illustrates the head 112a of the subject body <NUM> with respect to the opening <NUM> of the gantry <NUM> in the XY plane.

In addition, <FIG> illustrates an enlarged view of the head of the subject body <NUM>.

<FIG> illustrates the head 112a in a state in which the subject body <NUM> cannot face directly upward and faces obliquely upward. Note that for reference, the lower side of <FIG> illustrates the head 112a of the subject body <NUM> facing upward. The subject body <NUM> is lying on a table with the head rotated by an angle θ from a state of facing straight up.

In this case, since the face of the subject body <NUM> cannot be forcibly caused to face directly upward, scanning is performed with the face of the subject body <NUM> facing obliquely upward. Therefore, when a scout scan is executed, scout images <NUM> and <NUM> are obtained with the face of the subject body <NUM> obliquely oriented, as illustrated in <FIG>. Therefore, the processor executes segmentation based on the scout images <NUM> and <NUM> with the face of the subject body <NUM> obliquely oriented. However, if the segmentation is executed based on a scout image in which the face of the subject body <NUM> is oriented obliquely, there is a problem that the accuracy of the segmentation is lowered. For this reason, in step ST4, when the processor executes processing for identifying organs (for example, eyes) that are highly sensitive to radiation based on the scout images <NUM> and <NUM>, the detection accuracy of the organs becomes low. Consequently, selectively reducing eye exposure in diagnostic scans becomes difficult. In addition, since the diagnostic scan is executed with the face of the subject body <NUM> obliquely oriented, when the CT image obtained by the diagnostic scan is displayed on the display device <NUM>, the CT image <NUM> is displayed as in <FIG> with the face of the subject body <NUM> facing obliquely upward. Therefore, the doctor must perform a diagnosis of the subject body <NUM> while viewing the CT image <NUM> acquired with the face of the subject body <NUM> obliquely oriented. However, in imaging in the supine position, the face of the subject body <NUM> generally faces directly upward. Therefore, when diagnosing the head 112a based on the CT image <NUM> acquired with the face of the subject body <NUM> obliquely oriented, the doctor may find that the orientation of the face of the subject body <NUM> is different from the normal orientation causing an increase in the burden on the doctor during diagnosis.

Therefore, the CT device in Embodiment <NUM> is configured so as to be able to cope with the problem described above. The CT device of Embodiment <NUM> will be described below.

<FIG> is a diagram illustrating CT device operation flow when the subject body <NUM> is imaged in Embodiment <NUM>. Note that in executing the flow indicated in <FIG>, some steps can be omitted or added, some steps can be divided into a plurality of steps, some steps can be executed in a different order, and some steps can be repeated.

In step ST1, the operator calls the subject body <NUM> into the scan room and lays the subject body <NUM> on the table <NUM>. Here, as illustrated in <FIG> and <FIG>, it is assumed that the face of the subject body <NUM> can not face directly upwards and so is obliquely oriented.

The camera <NUM> starts imaging in the scan room <NUM> before the subject body <NUM> enters the scan room <NUM>. Signals captured by camera <NUM> are sent to the computer <NUM>. The computer <NUM> generates camera images based on signals received from the camera <NUM>. Therefore, the camera image of the subject in the scan room <NUM> can be generated before the subject body <NUM> enters the scan room <NUM>.

The field of view of the camera <NUM> includes the table <NUM> and the surrounding area thereof. Therefore, when the subject body <NUM> lies on the table <NUM>, the computer can generate a camera image of subject body <NUM> lying on table <NUM> based on signals from the camera <NUM>. Camera images are stored in the storing device <NUM>.

At step ST2, the operator establishes a scan plan for the scout scan. On the other hand, in step ST20, the computer <NUM> recognizes each portion (head, chest, abdomen, upper limbs, lower limbs, and the like) of the subject body <NUM> and the position of each portion based on the camera image, and the orientation of the portion of the subject body <NUM> on the table <NUM> to be imaged is determined. Here, the portion of the subject body <NUM> to be imaged is the head 112a. Therefore, the processor determines the orientation of the head 112a of the subject body <NUM>. The flow of step ST20 will be described in detail below with reference to <FIG>.

In step ST21, the computer <NUM> sets the central plane <NUM> that divides the head of the subject body <NUM> into left and right, based on the camera image <NUM> of the subject body <NUM>, as illustrated in <FIG>. For example, the computer <NUM> extracts a plurality of characteristic points (for example, eyebrows, eyes, nose, mouth, chin) on the surface of the face of the subject body <NUM> based on the camera image <NUM>, and based on the extracted characteristic points, the central plane <NUM> that divides the head 112a of the subject <NUM> into left and right can be determined.

In step ST22, the computer <NUM> approximates the head of the subject body <NUM> as an object <NUM> (for example, sphere, ellipsoid) having a symmetrical shape with respect to the YZ plane, as illustrated in <FIG>, and obtains the reference plane <NUM> that divides the object <NUM> in two in the X direction. The reference plane <NUM> is a plane parallel to the YZ plane. Therefore, the reference plane <NUM> approximates a plane that divides the face of the subject body <NUM> into left and right when the face of the subject body <NUM> is assumed to face an ideal direction suitable for examination (that is, in the Y direction). After determining the reference plane <NUM>, processing proceeds to step ST23.

In step ST23, the computer <NUM> obtains the rotation angle θ of the head of the subject body based on the central plane <NUM> and the reference plane <NUM>.

<FIG> is an explanatory diagram of a method of obtaining a rotation angle θ of the head of the subject body.

The upper left of <FIG> illustrates the central plane <NUM> obtained in step ST21, and the upper right of <FIG> illustrates the reference plane <NUM> obtained in step ST22. In addition, <FIG> illustrates the central plane <NUM> and the reference plane <NUM> as viewed from the Y direction, and the lower right of <FIG> illustrates the center plane <NUM> and the reference plane <NUM> as viewed from the Z direction.

The reference plane <NUM> obtained in step ST22 approximates a plane that divides the face of the subject body <NUM> into left and right when the face of the subject body <NUM> is assumed to face an ideal direction suitable for examination (that is, the Y direction). Therefore, the angle θ between the central plane <NUM> and the reference plane <NUM> can be obtained as the rotation angle θ of the head 112a of the subject body <NUM>. For example, when θ = <NUM>°, this indicates that the central plane <NUM> coincides with the reference plane <NUM>, in other words, this indicates that the face of the subject body <NUM> faces the ideal direction (directly upward). Therefore, θ = <NUM>° means that the head 112a of the subject body <NUM> is not tilted. On the other hand, if θ > <NUM>°, this indicates that the central plane <NUM> does not coincide with the reference plane <NUM> and indicates that the direction of the face of the subject body <NUM> is rotated from the ideal direction (directly upward) by an angle θ around the body axis (Z-axis). Therefore, θ > <NUM>° means that the head 112a of the subject body <NUM> is tilted.

Thus, in step ST20, the rotation angle θ can be obtained as a value representing the orientation of the head 112a of the subject body <NUM>. Here, it is assumed that θ = <NUM>°. After calculating the rotation angle θ, the process proceeds to step ST24.

At step ST24, the computer <NUM> corrects the scan plan for the scout scan based on the rotation angle θ obtained in step ST20.

<FIG> is an explanatory diagram of an example of a scout scan plan after correction. <FIG> is an explanatory diagram of the "Scout Plane" included in a scan plan.

The top of <FIG> illustrates the scout scan plans <NUM> and <NUM> before correction, and the bottom of <FIG> illustrates the scout scan plans <NUM> and <NUM> after correction.

At step ST24, the computer <NUM> corrects the value of the item "Scout Plane" of the scan plans <NUM> and <NUM> based on the rotation angle θ (orientation of the portion to be imaged).

The "Scout Plane" in the scout scan plan <NUM> before correction is set to an angle of "<NUM>°" corresponding to the initial position of the X-ray tube <NUM> and the "Scout Plane" in the scout scan plan <NUM> before correction is set to an angle of "<NUM>°" corresponding to the initial position of the X-ray tube <NUM>.

In Embodiment <NUM>, the rotation angle θ is calculated to be θ = <NUM>°, so the computer <NUM> corrects the value of the item "Scout Plane" in the scan plan <NUM> from <NUM>° to <NUM>° + <NUM>° = <NUM>° so that X-rays can be irradiated directly in front of the face of the subject body. In addition, the computer <NUM> corrects the value of the item "Scout Plane" of the scan plan <NUM> from <NUM>° to <NUM>° + <NUM>° = <NUM>° so that X-rays can be irradiated directly from the side of the face of the subject body. Therefore, the "Scout Plane" values of the scan plans <NUM> and <NUM> after correction are set to "<NUM>°" and "<NUM>°," respectively. "Scout Plane" = <NUM>° indicates that the X-ray tube <NUM> is arranged at a position P15 rotated clockwise by <NUM>° from the position P0 (angle of <NUM>°) on the path <NUM> as illustrated in <FIG>. In addition, "Scout Plane" = <NUM>° indicates that the X-ray tube <NUM> is arranged at a position P105 rotated clockwise by <NUM>° from the position P90 (angle of <NUM>°) on the path <NUM> as illustrated in <FIG>. Therefore, the computer <NUM> can determine two positions P15 and P105 on the path <NUM> where the X-ray tube <NUM> is positioned based on rotation angle θ (based on head orientation). After correcting the scan plan, processing proceeds to step ST3.

The scout scan is executed based on the corrected scout scan plans <NUM> and <NUM> (see <FIG>). In Embodiment <NUM>, first, a scout scan is executed based on the scout scan plan <NUM> (see <FIG>).

<FIG> is an explanatory diagram of the scout scan executed based on a corrected scout scan plan <NUM>.

When performing a scout scan based on the scout scan plan <NUM>, the gantry motor controller <NUM> (see <FIG>) controls the gantry motor so that the X-ray tube <NUM> is positioned at position P15 (angle <NUM>°) on the path <NUM>, rotated <NUM>° clockwise from angle <NUM>°.

Next, the table motor controller <NUM> (see <FIG>) then controls the table motor so as to move the cradle in the Z direction, while the X-ray controller <NUM> causes the X-ray tube <NUM> to irradiate X-rays.

The X-ray detector <NUM> detects X-rays irradiated from the X-ray tube <NUM> and that pass through the subject body <NUM>. The projection data detected by the X-ray detector <NUM> is collected by the DAS <NUM>. The DAS <NUM> performs prescribed processing, including sampling, digital conversion, and the like, on the acquired projection data and transmits the data to the computer <NUM> or image reconstruction unit <NUM>. A processor in the computer <NUM> or image reconstruction unit <NUM> reconstructs a scout image based on data obtained from scans executed with the X-ray tube <NUM> positioned at an angle of <NUM>°.

Therefore, when executing a scout scan according to the scan plan <NUM>, the X-ray tube <NUM> can be positioned at an angle of <NUM>° (position P15), as illustrated in <FIG>, so that a scout image taken from directly in front of the face of the subject body <NUM> can be acquired. <FIG> schematically illustrates a scout image <NUM> acquired according to the scan plan <NUM>.

When performing a scout scan according to the scan plan <NUM>, the gantry motor controller <NUM> controls the gantry motor so that the X-ray tube <NUM> rotates <NUM>° from position P15 (angle <NUM>°). Therefore, the X-ray tube <NUM> is positioned at a position of P105 (angle <NUM>°). While the table motor controller <NUM> moves the cradle in the Z direction, the X-ray controller <NUM> causes the X-ray tube <NUM> to irradiate X-rays while the X-ray tube <NUM> is positioned at an angle of <NUM>°.

Therefore, when executing a scout scan according to the scan plan <NUM>, the X-ray tube <NUM> can be positioned at an angle of <NUM>° (position P105), as illustrated in <FIG>, so that a scout image taken directly from the side of the head 112a of the subject body <NUM> can be acquired. <FIG> schematically illustrates a scout image <NUM> acquired in accordance with the scan plan <NUM>.

After executing the scout scan, the process proceeds to step ST4.

At step ST4, the operator makes a scan plan for a diagnostic scan. The operator, for example, refers to the scout images <NUM> and <NUM> to set the scan range for the diagnostic scan, which will be described later. The computer <NUM> also executes various processes based on the scout images <NUM> and <NUM>. For example, in Embodiment <NUM>, the computer <NUM> segments the scout images <NUM> and <NUM>, and based on the results of the segmentation, processing that identifies organs of the head 112a that is the portion to be imaged with high sensitivity to radiation (for example, the eyes) is executed. Organs with high sensitivity to radiation can be identified using trained models created using AI techniques such as deep learning and machine learning. A method for identifying organs with high sensitivity to radiation using a trained model is described below.

<FIG> is a diagram illustrating a flow for identifying an organ having high sensitivity to radiation using a trained model.

First, we describe how to generate a trained model that is used to identify organs that are highly sensitive to radiation. A trained model is created in advance during the learning phase prior to testing the subject body <NUM>.

In the learning phase, first, an original images set V is prepared. The original images set V includes, for example, a plurality of scout images acquired by executing a scan with the X-ray tube positioned at an angle of <NUM>° and a plurality of scout images acquired by executing a scan with the X-ray tube positioned at an angle of <NUM>°. Note that the original images set V may optionally include scout images obtained by executing a scan with the X-ray tube positioned at an angle other than <NUM>° and <NUM>°.

Next, preprocessing <NUM> is performed on the original images set V, as illustrated in <FIG>.

The pre-processing <NUM> includes, for example, image cropping, standardization, normalization, image inversion, image rotation, a magnification percentage change, and an image quality change. By performing preprocessing on the original images set V, a set VA of preprocessed scout images can be obtained. The set VA of preprocessed scout images is used as training data <NUM> for creating the trained model.

Next, the training data <NUM> is used to train the neural network <NUM>. The neural network <NUM> can use, for example, a convolutional neural network. In Embodiment <NUM>, the neural network <NUM> is trained to create a trained model <NUM> so as to output position data representing regions of organs (eyes) highly sensitive to radiation. This trained model <NUM> is stored in the storing device <NUM> (see <FIG>). The trained model <NUM> may be stored on an external storing device accessible by the CT device.

Therefore, the trained model <NUM> can be used to infer the eye position.

The right side of <FIG> illustrates the flow of inferring the eye position using the trained model <NUM>.

In step ST41, the computer <NUM> preprocesses scout images <NUM> and <NUM> obtained by scout scanning.

In step ST42, the computer <NUM> inputs the preprocessed scout images <NUM> and <NUM> as input images to the trained model <NUM>, and uses the trained model <NUM> to infer the positions of eyes that are highly sensitive to radiation.

After inferring eye positions, processing proceeds to step ST43.

In step ST43, the computer <NUM> sets the tube current of the X-ray tube <NUM> based on the inferred eye position and rotation angle θ so as to selectively reduce eye exposure during the diagnostic scan (see <FIG>).

<FIG> is an explanatory diagram of a method of determining weighting coefficients.

Based on the rotation angle θ of the head 112a of the subject body <NUM>, the computer <NUM> first determines an angle θ1 rotated clockwise from the rotation angle θ by an angle β and an angle θ2 rotated counterclockwise from the rotation angle θ by an angle γ. Although β = γ = <NUM>° in Embodiment <NUM>, β and γ may be angles other than <NUM>°, and β ≠ γ is feasible as well. In Embodiment <NUM>, since the rotation angle θ is θ = <NUM>°, calculation provides θ1 = θ + β = <NUM>° + <NUM>° = <NUM>°, and θ2 = θ - γ = <NUM>° - <NUM>° = -<NUM>°. Assuming that the clockwise direction from <NUM>° is the positive direction, -<NUM>° becomes +<NUM>°, so the following description will be continued with θ2 = <NUM>°.

Next, based on θ1 = <NUM>° and θ2 = <NUM>°, the computer <NUM> divides the path <NUM> along which the X-ray tube <NUM> moves into a path <NUM> on the side where the eyes of the head 112a are positioned and a path <NUM> on the side opposite the eyes (occipital side) of the head 112a.

In addition, the computer <NUM> also identifies the period during which the eyes are irradiated with X-rays during the diagnostic scan. Since the eyes are located on the surface side of the face of the subject body <NUM>, the X-ray tube <NUM> on path <NUM> moves closer to the eye than the X-ray tube <NUM> on path <NUM>. Therefore, the computer <NUM> sets the tube current of the X-ray tube <NUM> while moving along the path <NUM>, while X-rays are irradiated to the eyes, to be lower than the tube current of the X-ray tube <NUM> while moving along the path <NUM>.

The tube current is set in this manner. After the preparation for the diagnostic scan is complete, processing proceeds to step ST5 (see <FIG>).

At step ST5, a diagnostic scan of the head 112a is performed.

In a diagnostic scan, the tube current is adjusted such that the tube current of the X-ray tube <NUM> is low while the X-ray tube <NUM> is moving on the path <NUM> when X-rays are irradiated to the eyes. Therefore, the exposure of eyes that are highly sensitive to radiation can be selectively reduced. In Embodiment <NUM>, when determining the path <NUM>, β = γ = <NUM>° was used, but β and γ may be angles other than <NUM>°. For example, if further reduction in eye exposure is desired, β and γ can be set to angles greater than <NUM>° (for example, <NUM>°).

X-rays irradiated from the X-ray tube <NUM> are detected by the X-ray detector <NUM>. The projection data detected by the X-ray detector <NUM> is collected by the DAS <NUM>. The DAS <NUM> performs prescribed processing, including sampling, digital conversion, and the like, on the acquired projection data and transmits the data to the computer <NUM> or image reconstruction unit <NUM>. On the computer <NUM> or image reconstruction unit <NUM>, a processor reconstructs the CT image for diagnosis based on the data obtained from the scan. When reconstructing a CT image, the processor considers that the rotation angle θ of the head 112a is θ = <NUM>°, and reconstructs the CT image such that the rotation angle θ of the head depicted in the CT image changes from <NUM>° to <NUM>°. Therefore, the processor can reconstruct a CT image corrected so that the rotation angle of the head 112a is <NUM>°. <FIG> is a diagram illustrating a reconstructed CT image <NUM>. For comparison, <FIG> also illustrates a CT image <NUM> reconstructed without correcting the rotation angle θ = <NUM>° of the head 112a. As illustrated in <FIG>, the head 112a of the subject body <NUM> on the table <NUM> is tilted <NUM>° but the rotation angle of the head 112a is corrected to <NUM>° during image reconstruction so the CT image <NUM> is displayed with the tilt of the head 112a corrected.

In Embodiment <NUM>, the rotation angle θ of the head 112a of the subject body <NUM> is determined and the position (angle) of the X-ray tube <NUM> is set based on this rotation angle θ for executing the scout scan. Therefore, even if the subject body <NUM> can not face directly upwards (see <FIG>), scout images <NUM> and <NUM> (see <FIG>) that are substantially the same as the scout images <NUM> and <NUM> (see <FIG>) obtained when the subject body <NUM> faces directly upwards can be obtained. Therefore, even if the subject body <NUM> can not face directly upward, the scout image <NUM> captured from the front of the face of the subject body <NUM> and the scout image <NUM> captured from the side of the face of the subject body <NUM> can be obtained. In Embodiment <NUM>, segmentation is executed based on the scout images <NUM> and <NUM>, enabling segmentation accuracy of the scout images to be improved.

In addition, the CT image <NUM> (see <FIG>) obtained by means of the diagnostic scan has the rotation angle θ of the head 112a corrected from a rotation angle θ of the head 112a of <NUM>° to <NUM>°. Therefore, since the display device <NUM> (see <FIG>) displays the CT image <NUM> for the case of simulating the face of the subject body <NUM> facing directly upwards, the doctor can focus on interpretation work without being conscious that the face of the subject body <NUM> is obliquely oriented.

In Embodiment <NUM>, the subject body is imaged from two directions (<NUM>° and <NUM>°) to obtain scout images <NUM> and <NUM> (see <FIG>). However, it is also possible to image the subject body from only one of the two directions (<NUM>° and <NUM>°) and obtain only one of the scout images <NUM> and <NUM>.

In Embodiment <NUM>, the X-ray tube <NUM> is positioned at an angle of <NUM>° (in other words, the X-ray tube <NUM> is positioned on the surface side of the face of the subject body <NUM>), and X-rays are irradiated from the surface side of the face of the subject body <NUM> to obtain the scout image <NUM>. However, even if instead of positioning the X-ray tube <NUM> at an angle of <NUM>°, the X-ray tube <NUM> is positioned at an angle of <NUM>° that is the opposite side of <NUM>° (in other words, positioning the X-ray tube <NUM> on the back of the head side of the subject body <NUM>), and X-rays are irradiated from the back of the head side of the subject body <NUM>, a scout image including substantially the same morphological information and/or functional information as the scout image <NUM> can be obtained. Therefore, the scout image may be obtained by positioning the X-ray tube <NUM> at an angle of <NUM>° instead of <NUM>° and irradiating the subject body <NUM> with X-rays from the back side of the head.

In addition, in Embodiment <NUM>, the X-ray tube <NUM> is positioned at an angle of <NUM>° (in other words, the X-ray tube <NUM> is positioned on the left side of the subject body <NUM>), and X-rays are irradiated from the left side of the subject body <NUM> to obtain the scout image <NUM>. However, even if instead of positioning the X-ray tube <NUM> at an angle of <NUM>°, the X-ray tube <NUM> is positioned at an angle of <NUM>° that is the opposite side of <NUM>° (in other words, positioning the X-ray tube <NUM> on the right side of the subject body <NUM>), and X-rays are irradiated from the right side of the subject body <NUM>, a scout image including substantially the same morphological information and/or functional information as the scout image <NUM> can be obtained. Therefore, the scout image may be obtained by positioning the X-ray tube <NUM> at an angle of <NUM>° instead of <NUM>° and irradiating the subject body <NUM> with X-rays from the right side.

Further, in Embodiment <NUM>, in step ST22, the head of the subject body <NUM> is approximated as an object <NUM> (for example, a sphere, an ellipsoid) having a symmetrical shape with respect to the YZ plane, and the reference plane <NUM> is determined based on this object <NUM>. However, instead of determining the reference plane <NUM> based on the object <NUM>, a plane parallel to the YZ plane may be registered in advance as the reference plane <NUM> in the storing device. By registering a plane parallel to the YZ plane as the reference plane <NUM> in the storing device, the rotation angle θ can be determined without executing step ST22, thereby simplifying the flow of step ST20.

In Embodiment <NUM>, the operator manually sets the scan range of the diagnostic scan in step ST4 (see <FIG>) but in Embodiment <NUM>, a method of automatically setting the scan range using a trained model will be described.

<FIG> is a diagram illustrating a flow of automatically setting a scan range using a trained model.

First, a method of generating a trained model used to set the scan range will be described. A trained model is created in advance during the learning phase prior to testing the subject body <NUM>.

In the learning phase, first, an original images set W is prepared. The original images set W includes, for example, a plurality of scout images acquired by executing a scan with the X-ray tube <NUM> positioned at an angle of <NUM>° and a plurality of scout images obtained by executing a scan with the X-ray tube <NUM> positioned at an angle of <NUM>°. Note that if needed, the original images set W may include scout images obtained by performing scans with the X-ray tube <NUM> positioned at angles other than <NUM>° and <NUM>°.

Next, preprocessing <NUM> is executed on the original images set W, as illustrated in <FIG>.

The pre-processing <NUM> includes, for example, image cropping, standardization, normalization, image inversion, image rotation, a magnification percentage change, and an image quality change. By preprocessing the original images set W, a set WA of preprocessed scout images can be obtained. The set WA of preprocessed scout images is used as training data <NUM> for creating the trained model.

Next, the training data <NUM> is used to train the neural network <NUM>. For the neural network <NUM>, a convolutional neural network can be used, for example. In the Embodiment <NUM>, the neural network <NUM> is trained to create a trained model <NUM> so as to output scan range data indicating the start position and end position of the scan range. This trained model <NUM> can be stored in the storing device <NUM>.

Therefore, the computer <NUM> can use the trained model <NUM> to infer the start and end positions of the scan range.

The right side of <FIG> shows the flow of inferring the scan range using the trained model <NUM>.

In step ST411, the computer <NUM> preprocesses scout images <NUM> and <NUM> obtained by scout scanning.

In step ST421, the computer <NUM> inputs the preprocessed scout images <NUM> and <NUM> as input images to the trained model <NUM>, and uses the trained model <NUM> to infer the scan start position and scan end position of the scan range.

At step ST431, the computer <NUM> displays the inferred scan range on the scout image <NUM>. <FIG> is a schematic view of a scout image <NUM> and an inferred scan range <NUM> displayed on a display device.

In Embodiment <NUM>, a scan range <NUM> is inferred based on the scout image <NUM> obtained by positioning the X-ray tube <NUM> at an angle of <NUM>° (position P15) and the scout image <NUM> obtained by positioning the X-ray tube <NUM> at an angle of <NUM>° (position P105). Therefore, even if the subject <NUM> cannot face directly upwards in the supine position and is obliquely oriented, the scan range can be inferred based on the scout image <NUM> taken from the front of the face of the subject body <NUM> and the scout image <NUM> taken directly to the side of the face of the subject body <NUM>, thus improving the accuracy of inferring the scan range.

In Embodiment <NUM>, a plurality of cameras are provided, and an example of selecting a camera image suitable for obtaining the rotation angle θ of the head 112a from the camera images photographed by the plurality of cameras will be described.

<FIG> is a diagram illustrating a plurality of cameras provided in a scan room in Embodiment <NUM>.

The scan room <NUM> is equipped with a plurality of cameras. In Embodiment <NUM>, an example in which three cameras <NUM>, <NUM>, and <NUM> are provided on the ceiling <NUM> of the scan room <NUM> will be described, but two cameras may be provided, or four or more cameras may be provided.

<FIG> is a diagram illustrating the flow in Embodiment <NUM>.

In comparison with Embodiment <NUM>, Embodiment <NUM> is different in step ST20, but other steps are the same as those in Embodiment <NUM>. Therefore, in describing Embodiment <NUM>, step ST20 will be mainly described.

<FIG> is an explanatory diagram of step ST20 in Embodiment <NUM>.

In step ST21, the computer <NUM> (see <FIG>) extracts a plurality of feature points (for example, eyebrows, eyes, nose, mouth, and jaw) on the face surface of the subject body <NUM> from the camera image <NUM> of the subject <NUM> acquired by the camera <NUM>. Furthermore, as illustrated in <FIG>, the computer <NUM> obtains a central plane <NUM> that divides the head 112a of the subject body <NUM> into left and right based on the plurality of extracted feature points. After determining the central plane <NUM>, processing proceeds to step ST211.

In step ST211, the computer <NUM> determines a plane <NUM> that traverses the camera <NUM> and head 112a and is parallel to the Z-axis direction (axial direction) based on position data indicating the position of the camera <NUM> and position data indicating the position of the head 112a of the subject body <NUM>. Note that the position data indicating the position of the camera <NUM> is data obtained in advance before the examination of the subject body <NUM>, and is stored in a storing device (for example, the storing device <NUM>). The computer <NUM> can retrieve position data indicating the position of the camera <NUM> from a storing device. Position data indicating the position of the head 112a of the subject body <NUM> is data that can be obtained based on the camera image <NUM>. Therefore, the computer <NUM> can determine the plane <NUM> that traverses the camera <NUM> and the head 112a and is parallel to the Z-axis direction (axial direction). After determining the plane <NUM>, processing proceeds to step ST212.

In step ST212, the computer <NUM> determines the angle α formed by the plane <NUM> and plane <NUM>, and obtains this angle α as the angle α indicating the mounting position of the camera <NUM> with respect to the central plane <NUM> of the face of the subject body <NUM>. In <FIG>, it is assumed that α = α1. This α = α1 is stored in a storing device (for example, storing device <NUM>). After determining the angle α = α1 of the camera <NUM>, the angles α of the other cameras <NUM> and <NUM> are also obtained according to steps ST21, ST211, and ST212.

<FIG> is an explanatory diagram of a method of obtaining the angle α of the camera <NUM>.

In step ST21, the computer <NUM> extracts a plurality of feature points (for example, eyebrows, eyes, nose, mouth, and jaw) on the face surface of the subject body <NUM> from the camera image <NUM> of the subject <NUM> acquired by the camera <NUM>. Furthermore, as illustrated in <FIG>, the computer <NUM> obtains a central plane <NUM> that divides the head 112a of the subject body <NUM> into left and right based on the plurality of extracted feature points.

In step ST212, the computer <NUM> determines the angle α formed by the plane <NUM> and plane <NUM>, and obtains this angle α as the angle α indicating the mounting position of the camera <NUM> with respect to the central plane <NUM> of the face of the subject body <NUM>. In <FIG>, it is assumed that α = α2. This α = a2 is stored in the storing device. After determining the angle α = α2 of the camera <NUM>, the angles α of the other camera <NUM> are also obtained according to steps ST21, ST211 and ST212.

<FIG> is an explanatory diagram of a method of obtaining the angle α of a camera <NUM>.

In step ST211, the computer <NUM> determines a plane <NUM> that traverses the camera <NUM> and head 112a and is parallel to the Z-axis direction (axial direction) based on position data indicating the position of the camera <NUM> and position data indicating the position of the head 112a of the subject body <NUM>. Note that the position data indicating the position of the camera <NUM> is data obtained in advance before the examination of the subject body <NUM>, and is stored in a storing device. The computer <NUM> can retrieve position data indicating the position of the camera <NUM> from a storing device. Position data indicating the position of the head 112a of the subject body <NUM> is data that can be obtained based on the camera image <NUM>. Therefore, the computer <NUM> can determine the plane <NUM> that traverses the camera <NUM> and the head 112a and is parallel to the Z-axis direction (axial direction). After determining the plane <NUM>, processing proceeds to step ST212.

In step ST212, the computer <NUM> determines the angle α formed by plane <NUM> and plane <NUM>, and obtains this angle α as the angle α indicating the mounting position of the camera <NUM> with respect to the central plane <NUM> of the face of the subject body <NUM>. In <FIG>, it is assumed that α = α3. This α= α3 is stored in the storing device.

Therefore, the angles α of cameras <NUM>, <NUM>, and <NUM> can be calculated as α1, α2, and α3, respectively. After calculating these angles α1, α2, and α3, processing proceeds to step ST213.

In step ST213, the computer <NUM> determines the rotation angle θ of the head 112a of the subject body <NUM> from the camera image <NUM> (see <FIG>), the camera image <NUM> (see <FIG>), and the camera image <NUM> (see <FIG>) and determines which camera image to use. The rotation angle θ of the head 112a of the subject body <NUM> is a value determined with reference to the central plane that divides the face of the subject body <NUM> into left and right. Therefore, in order to determine the rotation angle θ of the head 112a of the subject body <NUM> as accurately as possible, determining the central plane dividing the face of the subject body <NUM> into left and right as accurately as possible is important. Since the central plane is determined using the camera image, determining the central plane based on the camera image obtained from the camera positioned directly in front of the face of the subject body <NUM> is considered ideal for determining the central plane as accurately as possible. Therefore, in Embodiment <NUM>, of the camera images <NUM>, <NUM>, and <NUM> (see <FIG>), the camera image acquired from the camera closest to the position directly in front of the face of the subject body <NUM> is set as the camera image used to determine the rotation angle θ of the head. Of the cameras <NUM>, <NUM>, and <NUM>, the camera closest to the position directly in front of the subject body <NUM> is the camera with the smallest angle α. The closer the camera is to the position directly in front of the face of the subject body <NUM>, the smaller the value of the angle α of the camera. Therefore, by specifying the smallest angle from among the angles α1, α2, and α3, the camera closest to the position directly in front of the face of the subject body <NUM> can be specified. In Embodiment <NUM>, among the camera angles α1, α2, and α3, the minimum value is α2. Therefore, of cameras <NUM>, <NUM>, and <NUM>, the computer <NUM> specifies the camera <NUM> with angle α2 as the camera closest to the position directly in front of the face of the subject body <NUM>. Furthermore, the computer <NUM> determines the camera image <NUM> (see <FIG>) acquired by the camera <NUM> as the camera image to be used for determining the rotation angle θ of the head 112a of the subject body <NUM>. After determining the camera image <NUM>, processing proceeds to step ST22.

In step ST22, as described in Embodiment <NUM>, the reference plane <NUM> (see <FIG>) for dividing the object <NUM> approximating the shape of the head 112a is obtained. In step ST23, the angle between the central plane <NUM> (see <FIG>) determined from camera image <NUM> and the reference plane <NUM> is obtained as the rotation angle θ of the head.

Since step ST25 and subsequent steps are the same as those in Embodiment <NUM> or Embodiment <NUM>, the description thereof will be omitted.

In Embodiment <NUM>, of the camera images <NUM>, <NUM>, and <NUM> (see <FIG>), the camera image <NUM> acquired from the camera closest to the position directly in front of the face of the subject body <NUM> is set as the camera image used to determine the rotation angle θ of the head. Therefore, the rotation angle θ of the head can be calculated using the highly reliable central plane <NUM> as a plane dividing the face of the subject body into right and left. Therefore, accuracy of scout image segmentation can be improved and the quality of CT images obtained by diagnostic scanning can be further improved.

In Embodiments <NUM> to <NUM>, the case of imaging the head 112a of the subject body <NUM> has been described. However, the present invention is not limited to imaging the head 112a, and can be applied to imaging portions other than the head 112a. For example, when imaging the chest, the orientation of the chest can be obtained based on the difference in height between the left and right shoulders. Also, when the imaging region is the abdomen, the orientation of the abdomen can be determined based on the difference in height on the left and right sides of the waist. Furthermore, if the imaging region includes the chest and abdomen, the orientation of the imaging region can be determined based on both the difference in height between the left and right shoulders and the difference in height between the left and right sides of the waist.

Claim 1:
A medical device (<NUM>), comprising:
a gantry (<NUM>) including an X-ray tube (<NUM>) that can rotate on a path centered on a rotation axis and an X-ray controller (<NUM>) that controls the X-ray tube;
a table (<NUM>) on which a subject body (<NUM>) can lie; and
at least one processor;
the medical device executing a first scan on the subject body, characterised in that
the processor executes operations including:
determining a first position on the path for arranging the X-ray tube for the first scan based on the direction the portion of the subject body to be imaged is facing, and
controlling the X-ray tube by means of the X-ray controller such that the X-ray tube irradiates X-rays from said first position.