JP6068179B2 - X-ray computed tomography system - Google Patents

Description

  Embodiments described herein relate generally to an X-ray computed tomography apparatus.

  In an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus), a subject such as a patient is placed on a couch top and scanned while rotating the X-ray tube around the subject. It is carried out. In this scan, for example, as shown in FIG. 9, the X-ray tube 10 is rotated in a spiral shape. That is, a helical that collects projection data by placing a subject such as a patient on the top and moving the top in the Z-axis direction (the subject's axial direction) while rotating the X-ray tube 10 around the subject. A scan is performed.

  In an X-ray CT apparatus, a real-time reconstruction function for reconstructing an image in real time in synchronization with scanning is widely used. In the real-time reconstruction function, when the X-ray tube 10 is spirally rotated around the subject, the projection data corresponding to one rotation is regarded as data on one circular orbit a and reconstructed. The tomographic image data is acquired.

  However, since the real-time reconstruction function does not consider the influence of the cone angle, as shown in FIG. 10, a range in which sufficient image quality can be obtained within the range (number of imaging columns × slice thickness) Rd of the X-ray detector 11. Rg is narrow. For this reason, the image quality at the position near the end of the number of imaging rows of the X-ray detector 11 is degraded. The cone angle greatly affects the image quality as the number of shooting columns increases.

  Further, when real-time reconstruction is applied to the helical shuttle scan, only a part of the images in the range Rd (range that can be reconstructed) of the X-ray detector 11 is displayed. Specifically, only an image in the range Rg where sufficient image quality can be obtained is displayed. Here, the range Rg in which sufficient image quality can be obtained is a range of about two columns at the center of the number of imaging columns of the X-ray detector 11 or a range near the center of the number of imaging columns of the X-ray detector 11.

  Further, in the helical shuttle scan, when the X-ray tube 10 and the X-ray detector 11 are continuously swung while the top plate is reciprocated in the body axis direction, one rotation and a pause time are taken at both ends of the scan range. The top is stopped for the minutes. However, in the helical shuttle scan, even when the top plate stops at both ends of the scan range, an image at the center position of the number of imaging columns is displayed as described above. That is, in the helical shuttle, even when the top plate stops at both ends of the scan range, as described above, images at the positions at both ends of the number of photographing columns are not displayed.

  For this reason, the helical shuttle does not know if the extra range is scanned. If an extra range is scanned, the exposure of the subject is increased.

JP 2011-4915 A

  As described above, in the real-time reconstruction of the helical shuttle, images at positions at both ends of the imaging range are not displayed, so it is not known even if the extra range is scanned. If an extra range is scanned, the exposure of the subject is increased.

  The object is to provide an X-ray computed tomography apparatus capable of reducing the exposure by expanding the range of the image displayed in synchronization with the helical shuttle scan, thereby preventing the scan of the extra range.

  The X-ray computed tomography apparatus of the embodiment includes an X-ray tube, a bed, an X-ray detector, setting means, a scanning unit, a volume reconstruction unit, a real-time reconstruction unit, and a display unit.

  The X-ray tube emits X-rays.

  The bed has a top plate on which the subject is placed.

  The X-ray detector detects the X-ray transmitted through the subject.

  The setting means sets scan conditions including a helical shuttle scan range.

  The scanning unit reciprocates the top plate in the body axis direction of the subject while rotating the X-ray tube around the subject based on the scanning condition.

  The volume reconstruction unit reconstructs volume of tomographic image data based on projection data acquired from an output signal of the X-ray detector with respect to positions at both ends of the scan range.

  The real-time reconstruction unit reconstructs tomographic image data in real time based on projection data acquired from an output signal of the X-ray detector with respect to an intermediate position between the positions of both ends.

  The display unit displays the tomographic image data reconstructed by the volume reconstruction unit or the real-time reconstruction unit.

  The scan condition includes the scan range, a reconstruction time Tv required for the volume reconstruction, a pause time Ts during the stop of the top plate, and the tomographic image after the top plate is moved again from the stop. And the maximum time Tn at which data may not be displayed.

  The setting means includes a determination unit, a sending unit, and an output unit.

  The determination unit determines whether the reconstruction time Tv, the pause time Ts, and the maximum time Tn satisfy a relationship of Tv <Ts or a relationship of Tv−Ts ≦ Tn.

  The transmission unit sets the scan condition when the determination result satisfies any of the relations, and transmits the scan condition to the scan unit.

  The output unit outputs a message indicating that the pause time Ts cannot be set when none of the determined results.

It is a schematic diagram which shows the structure of the computer tomography apparatus which concerns on one Embodiment. It is a flowchart for demonstrating the operation | movement in the embodiment. It is a schematic diagram which shows the movement of the X-ray tube and movement of a top plate for demonstrating the outline | summary of one Embodiment. It is a schematic diagram which shows the image display range for demonstrating the outline | summary of one Embodiment. It is a schematic diagram which shows the image display range in the both ends of the scanning range for demonstrating the outline | summary of one Embodiment. It is a schematic diagram which shows the relationship of the scanning conditions for demonstrating the outline | summary of one Embodiment. It is a schematic diagram which shows the other relationship of the scanning conditions for demonstrating the outline | summary of one Embodiment. It is a schematic diagram which shows the other relationship of the scanning conditions for demonstrating the outline | summary of one Embodiment. It is a schematic diagram for demonstrating a general helical scan. It is a schematic diagram for demonstrating general real-time reconstruction.

  Hereinafter, a computer tomography apparatus (X-ray CT apparatus) according to an embodiment will be described with reference to the drawings, but before that, an outline of the embodiment will be described.

  In the X-ray CT apparatus, during the helical shuttle, as shown in FIG. 3A, the X-ray tube rotates or moves (when the top plate is moved) or rotates (when the top plate is stopped). As shown, the top plate reciprocates.

  As shown in FIG. 4, the X-ray CT apparatus is in the middle of reciprocating the top 4 along the Z-axis direction between the center positions p1 and p2 of the number of imaging rows of the X-ray detector 11 at both ends of the scan range. Then, an image reconstructed in real time (hereinafter also referred to as a real time image) is displayed. The range for displaying the real-time image (hereinafter also referred to as the real-time display range) is limited to the inside of the center positions p1 and p2 of the number of imaging columns of the X-ray detector 11. On the other hand, the image display range of the embodiment described later is the entire range within the scan range, and an image in a range outside the center positions p1 and p2 of the number of imaging columns of the X-ray detector 11 can also be displayed. .

  Here, the image display range when the top 4 stops at both ends of the scan range will be supplementarily described with reference to FIG.

  The X-ray CT apparatus changes the range Rg of the X-ray detector 11 when the sufficient range of image quality can be obtained in the changed range ΔR1 when the range Rg in which sufficient image quality can be obtained is changed to the outer range ΔR1. A real-time image of the subsequent range ΔR1 is displayed. Note that changing the range Rg of the X-ray detector 11 to the range ΔR1 corresponds to changing the imaging row of the X-ray detection elements selected in the X-ray detector 11.

  When the outside range ΔR1 is changed from the range Rg for displaying the real-time image, the range (ΔR2) that is not displayed yet remains in the range Rd of the X-ray detector 11 although the real-time display range is expanded as compared with the conventional range. The range ΔR2 not yet displayed is also a range in which sufficient image quality cannot be obtained by real-time reconstruction.

  For this range ΔR2, for example, by switching to another reconstruction, an image with sufficient image quality can be reconstructed and displayed. When the process of another reconfiguration is slow and cannot be synchronized, the condition and the section may be changed to cope with it.

  As another reconstruction, for example, the same method as the reconstruction method after scanning (for example, normal volume reconstruction (reconstruction of one rotation scan)) is used.

  At this time, since the volume reconstruction speed is slower than the real-time reconstruction speed, there is a possibility that the top 4 resumes the movement before the volume reconstruction image is displayed.

  From the viewpoint of eliminating this possibility, for example, the scan condition is set as follows.

  The time required for volume reconstruction is assumed to be reconstruction time Tv. The time during which the top 4 is stopped is defined as a pause time Ts. At this time, as shown in FIG. 6, when the relationship of the following expression (1) is satisfied, an image is not displayed in real time while the top 4 is stopped, but the volume is created before the top 4 resumes moving. An image is displayed.

Tv <Ts (1)
Thus, when the relationship of the expression (1) is satisfied, there is no problem because the user can check the image in the scan range and set the next scan range.

  If the relationship of (1) is not satisfied, that is, if the relationship of the following equation (2) is satisfied, the volume reconstruction is completed because the volume reconstruction is in progress when the top 4 resumes moving. Do not switch to real-time reconfiguration until

Ts ≦ Tv (2)
As described above, when the switching to the real-time reconstruction is not executed, the real-time image during the backward scan is not displayed for a long time when the reconstruction time Tv is very long.

  To avoid this problem, the maximum time during which the real-time image need not be displayed after resuming the movement of the top 4 is set as the maximum time Tn, and the problem is avoided based on the relationship including the maximum time Tn. Note that the value of the maximum time Tn is input by a user operation.

  Specifically, as shown in FIG. 7, when the relationship of the following equation (3) is satisfied, that is, when the relationship of the equation (3 ′) is not satisfied as shown in FIG. Notification is made that there is an image that is not displayed in real time even during movement, or the pause time Ts is changed.

Tv-Ts> Tn (3)
Tv−Ts ≦ Tn (3 ′)
When changing the downtime Ts, for example, the changed downtime Ts ′ may be calculated as shown in the following equation (4).

Ts ′ = Tv−Ts−Tn (4)
The changed rest time Ts ′ is not limited to the equation (4), and may be calculated as shown in the equation (5), for example.

Ts ′ = Tv−Tn (5)
However, before changing the suspension time Ts, it is confirmed with the user whether or not the change of the suspension time Ts is acceptable. If the change of the pause time Ts is not acceptable, the image of the range ΔR1 outside the conventional real-time display range is stopped while the top 4 is stopped, as shown in FIG. 5, without switching to volume reconstruction. To display. In this case, although the range ΔR2 that is not yet displayed remains at both ends of the scan range, the real-time display range is widened compared to the conventional case, so that an extra range scan is prevented.

  These scan conditions are set before scanning (when the scan is planned).

  If the scan range includes an extra range and the scan range in the next scan (next round-trip) can be shortened, the user can change the scan range after the next scan by resetting the scan range. (Shortening).

  The above is the outline of one embodiment. Subsequently, one embodiment will be specifically described.

<One Embodiment>
FIG. 1 is a schematic diagram showing the configuration of a computed tomography apparatus (X-ray CT apparatus) according to an embodiment. The X-ray CT apparatus includes a gantry device 1, an operation console 2, and a bed device 3. The couch device 3 has a top plate 4 provided so as to be slidable in the Z-axis direction. A subject P such as a patient is placed on the top 4.

  In the gantry device 1, an X-ray tube 10 and a two-dimensional X-ray detector 11 are arranged to face each other. A subject P is disposed between the X-ray tube 10 and the X-ray detector 11. A diaphragm 12 and the like are provided on the exposure surface side of the X-ray tube 10. In addition, the gantry device 1 includes a high pressure generator 13, a diaphragm driving device 14, a rotation driving device 15, a data collection unit (DAS) 16, and a gantry control unit 17.

The X-ray tube 10 exposes X-rays by applying a high voltage from the high voltage generator 13. The diaphragm 12 has a diaphragm diameter that is variable by driving the diaphragm driving device 14, and adjusts the X-ray dose emitted from the X-ray tube 10.
The X-ray detector 11 detects X-rays exposed from the X-ray tube 10 and transmitted through the subject P, and outputs an electrical signal corresponding to the X-ray dose. The X-ray detector 11 is configured by arranging a plurality of X-ray detection elements in a line and arranging a plurality of the line-shaped element arrays. The line-shaped element rows are configured in multiple rows of 32 to 64 rows, for example.

The X-ray tube 10 and the X-ray detector 11 are continuously rotated around the subject P by the rotation driving device 15. Thereby, the X-ray tube 10 rotates and moves along, for example, a circular movement locus. In this case, the X-ray tube 10 and the X-ray detector 11 rotate and move continuously repeatedly on the movement locus of one circle.
The data collection unit 16 collects each electric signal output from each X-ray detection element of the X-ray detector 11, converts it into a digital signal, and sends it to the operation console 2 as collected data.

  The gantry control unit 17 controls the couch device 3, the high pressure generation unit 13, the aperture drive device 14, the rotation drive device 15, and the data collection unit 16 based on the operation command received from the console control unit 22. As a result, the gantry control unit 17 emits X-rays from the X-ray tube 10, and repeatedly rotates the X-ray tube 10 and the X-ray detector 11 continuously on the movement locus of one circle. Then, the top plate 4 of the bed apparatus 3 is helically scanned by sliding in the Z-axis direction.

  On the other hand, the operation console 2 is a user interface for performing operations such as scan condition setting, scanning, diagnosis, image processing of captured images, and management of tomographic image data by executing a program by the CPU in the operation console 2. . The operation console 2 includes an input device 20, a scan condition setting unit 21a, a condition changing unit 21b, a console control unit 22, a preprocessing unit 23, a projection data storage unit 24, a reconstruction processing unit 25, an image storage unit 26, and an image processing unit. 27 and a display device 28.

The input device 20 receives operations such as scan condition setting, scanning, diagnosis, image processing of captured images, and management of tomographic image data by the user.
The scan condition setting unit 21 a sets a scan condition including the scan range of the helical shuttle based on an operation input received from the input device 20. The scan conditions include, for example, a scan range, a reconstruction time Tv required for volume reconstruction, a pause time Ts when the top 4 is stopped, and the tomographic image data after resuming the movement of the top 4 from the stop. And the maximum time Tn that may not be displayed.

  Here, the scan condition setting unit 21a has the following functions (f21a-1) to (f21a-3).

  (f21a-1) A determination function that determines whether the reconstruction time Tv, the pause time Ts, and the maximum time Tn satisfy the relationship of Tv <Ts or the relationship of Tv−Ts ≦ Tn.

  (f21a-2) A sending function that sets a scan condition and sends the scan condition to the scan unit (console control unit 22) when any of the relations is satisfied as a result of the determination.

  (f21a-3) An output function for outputting a message indicating that the suspension time Ts cannot be set when the result of determination is NO. Here, the message may represent that the suspension time Ts cannot be set and an inquiry about whether or not the suspension time Ts can be changed. Accordingly, when the scan condition setting unit 21a receives an input indicating that the pause time Ts can be changed after the message is output, the scan condition setting unit 21a changes the value of the pause time Ts to Tv−Tn, and the determination function (f21a-1). May be provided with a pause time changing function (f21a-4) (pause time changing unit) for controlling to re-execute.

  The condition changing unit 21b changes a preset scanning condition by an operation input received from the input device 20. For example, when the condition changing unit 21b receives an input of a scan range after the next reciprocating movement while displaying the tomographic image data reconstructed by the volume reconstructing function of the reconstruction processing unit 25, the condition changing unit 21b starts the next reciprocating movement Has a scan range change function (scan range change unit) for instructing the scan unit to change the current scan range to the scan range in which the input is accepted.

  When the console control unit 22 receives a scan condition from the scan condition setting unit 21a or the condition change unit 21b, based on the scan condition, the preprocessing unit 23, the projection data storage unit 24, the reconstruction processing unit 25, and the image storage unit 26, control the operation of the image processing unit 27 and the display device 28, and send an operation command based on the scanning condition to the gantry control unit 17. However, the console control unit 22 is not limited to the control based on the scanning condition, and controls the operations of the units 23 to 27 and the display device 28 in accordance with the operation input received from the input device 20, and the operation command based on the operation input It also has a function of sending to the control unit 17. Here, the console control unit 22, the X-ray tube 10, the X-ray detector 11, the rotation driving device 15, and the bed device 3 constitute a scanning unit. The scanning unit reciprocates the top 4 in the body axis direction of the subject P while rotating the X-ray tube 10 around the subject P based on the scanning conditions.

The preprocessing unit 23 processes the collected data from the data collecting unit 16 into reconfigurable projection data.
The projection data storage unit 24 stores the projection data processed by the preprocessing unit 23.
The reconstruction processing unit 25 reads the projection data stored in the projection data storage unit 24, and reconstructs tomographic image data of the subject P based on the read projection data in volume reconstruction or in real time. Here, the reconstruction processing unit 25 has the following functions (f25-1) to (f25-2).

  (f25-1) A volume reconstruction function that reconstructs tomographic image data based on projection data acquired from the output signal of the X-ray detector 11 with respect to the positions at both ends of the scan range.

  (f25-2) A real-time reconstruction function that reconstructs tomographic image data in real time based on projection data acquired from the output signal of the X-ray detector 11 with respect to an intermediate position sandwiched between positions at both ends of the scan range. Note that the real-time reconstruction function (f25-2) is suspended during the operation of the volume reconstruction function (f25-1). The volume reconfiguration function (f25-1) pauses during the operation of the real-time reconfiguration function (f25-2).

  The image storage unit 26 stores the tomographic image data reconstructed by the reconstruction processing unit 25.

The image processing unit 27 processes the tomographic image data in the image storage unit 26 into display data in a format that can be easily displayed on the display device 28.
The display device 28 includes, for example, a liquid crystal display, and displays and outputs the display data processed by the image processing unit 27 on the liquid crystal display or the like. Here, the image storage unit 26, the image processing unit 27, and the display device 28 constitute a display unit. The display unit displays the tomographic image data reconstructed by the reconstruction processing unit 25 (its volume reconstruction function or real-time reconstruction function).

  The console control unit 22 displays tomographic image data on the display device 28 based on the exposure amount of the X-rays exposed to the subject P based on the projection data stored in the projection data storage unit 24. Hide.

  Next, the operation of the X-ray CT apparatus configured as described above will be described using the flowchart shown in FIG.

  When the input device 20 receives an input of a scan condition by a user operation, an input of scan, diagnosis, image processing of a captured image, management of tomographic image data, or the like, the input device 20 sends the received input to the scan condition setting unit 21a.

  Based on the input received from the input device 20, the scan condition setting unit 21a starts setting the scan conditions for the helical scan.

  First, after the scan condition setting unit 21a resumes the scan range, the reconstruction time Tv required for volume reconstruction, the pause time Ts during which the top 4 is stopped, and the movement of the top 4 from the stop. A maximum time Tn at which tomographic image data may not be displayed is temporarily set (ST1 to ST3).

  Subsequently, the scan condition setting unit 21a determines whether the reconstruction time Tv, the pause time Ts, and the maximum time Tn satisfy the relationship of Tv <Ts or the relationship of Tv−Ts ≦ Tn, respectively (ST4 to ST5). ).

  As a result of the determination in steps ST4 to ST5, the scan condition setting unit 21a sets the temporarily set scan condition and sends the scan condition to the console control unit 22 as no problem if any of the relationships is satisfied. (ST6).

  On the other hand, when the results determined in steps ST4 to ST5 are all negative, the scan condition determination unit 21a displays a message indicating a table indicating that the suspension time Ts cannot be set and whether the suspension time Ts can be changed. Output (ST7).

  After the output of the message, the scan condition setting unit 21a receives an input indicating that the suspension time Ts can be changed, changes the value of the suspension time Ts to Tv−Tn (ST8), and repeats the determinations of steps ST4 to ST5. Run.

  Further, when the scan condition setting unit 21a receives an input indicating whether or not the pause time Ts is changed after outputting the message in step ST7, the scan condition setting unit 21a notifies the user that the images at both ends of the scan range are not displayed in real time. At the same time, the temporarily set scanning conditions are set, and the scanning conditions are sent to the console control unit 22 (ST9).

  With the execution of step ST6 or step ST9 described above, the setting of scan conditions is completed.

  When receiving the scanning condition, the console control unit 22 issues an operation command corresponding to the scanning condition to the gantry control unit 17. The gantry control unit 17 receives the operation command from the console control unit 22 and controls the couch device 3, the high pressure generation unit 13, the aperture drive device 14, the rotation drive device 15, and the data collection unit 16. .

  As a result, the X-ray tube 10 and the X-ray detector 11 repeatedly rotate continuously on the movement locus of one circle, and the top plate 4 of the bed apparatus 3 slides in the Z-axis direction. . At this time, the X-ray tube 10 emits X-rays. The X-rays exposed from the X-ray tube 10 pass through the subject P placed on the top 4 and enter the X-ray detector 11. The X-ray detector 11 detects X-rays that have passed through the subject P and outputs an electrical signal corresponding to the X-ray dose. That is, a helical scan is performed.

During this helical scan, the data collection unit 16 collects each electrical signal output from each X-ray detection element of the X-ray detector 11 and converts it into digital data and sends it to the operation console 2 as collected data.
The preprocessing unit 23 of the operation console 2 processes the collected data into reconfigurable projection data. The projection data is stored in the projection data storage unit 24.
Next, the console control unit 22 switches the function of the reconstruction processing unit 25 to a volume reconstruction function or a real-time reconstruction function based on the scan condition.

  Thereby, the reconstruction processing unit 25 reconstructs the volume of the tomographic image data based on the projection data in the projection data storage unit 24 with respect to the positions at both ends of the scan range.

  Further, the reconstruction processing unit 25 reconstructs tomographic image data in real time based on the projection data in the projection data storage unit 24 with respect to an intermediate position sandwiched between the positions at both ends of the scan range.

  The tomographic image data reconstructed by the reconstruction processing unit 25 is stored in the image storage unit 26.

  Next, the image processing unit 27 reads the tomographic image data in the image storage unit 26, processes the tomographic image data of the subject P into display data in a format that can be easily displayed on the display device 28, and sends the display data to the display device 28. . The display device 28 displays and outputs the display data processed by the image processing unit 27 on a liquid crystal display or the like. Thereby, a user such as a doctor visually recognizes the tomographic image data of the subject P displayed on the liquid crystal display or the like.

  Thereby, the user can confirm that the scan range includes the target region. When the scan range includes an extra range other than the target region, the scan range is reset so as to exclude the extra range.

  Specifically, the user operates the input device 20 so as to reset the scan range.

  The input device 20 sends the user's operation input to the condition changing unit 21b.

  The condition changing unit 21b changes a preset scanning condition by this operation input. For example, when the condition changing unit 21b receives an input of a scan range after the next reciprocating movement while displaying the tomographic image data reconstructed by the volume reconstructing function of the reconstructing processing unit 25, the condition changing unit 21b starts the next reciprocating movement. In this case, the console control unit 22 of the scan unit is instructed to change the current scan range to the scan range in which the input is accepted.

  In response to this instruction, the console control unit 22 performs a preprocessing unit 23, a projection data storage unit 24, a reconstruction processing unit 25, an image storage unit 26, an image processing unit 27, Operation control of the display device 28 is performed, and an operation command based on the scanning condition is sent to the gantry control unit 17.

  Thereby, a helical scan is executed according to the changed scan range, and tomographic image data corresponding to the changed scan range is displayed on the display device 28.

  As described above, according to the present embodiment, whether the reconstruction time Tv, the pause time Ts, and the maximum time Tn included in the scan condition satisfy the relationship of Tv <Ts or the relationship of Tv−Ts ≦ Tn, respectively. If any relationship is satisfied, a scan condition is set. Further, the tomographic image data is reconstructed in volume with respect to the positions at both ends of the scan range included in the scan condition, and the tomographic image data is reconstructed in real time with respect to an intermediate position sandwiched between the positions of the both ends. Note that both ends of the scan range are not included in the conventional real-time display range. Thus, compared with the conventional real-time display range, by expanding the range of the image displayed in synchronization with the helical shuttle scan, it is possible to prevent the excessive range scan and reduce the exposure.

  Supplementally, in the helical shuttle, the real-time reconstruction is executed in the middle of the scan range and the volume reconstruction is executed at both ends of the scan range based on the scan condition satisfying the predetermined relationship, so that all the scan ranges within the scan range are executed. It is possible to display and confirm the tomographic image data of the range.

  As a result, it is possible to exclude the extra range from the scan range by resetting the scan range according to the confirmation result, so the exposure range after the next scan (next round-trip) is narrowed and the exposure dose Can be reduced.

  For resetting the scan range, a normal method used for setting the scan range may be used. For example, the following methods (i) to (iii) may be used as appropriate.

  (i) A method of specifying while browsing an image being scanned (a real-time image or an image in a range ΔR1 outside the real-time display).

  (ii) A method of marking with a skip button or the like when the image is automatically updated. (iii) A method in which the scan range is reset to a short range by inputting the scan range.

  Moreover, this embodiment can also be modified as follows. That is, the reconstruction method during scanning may be a reconstruction method that considers the cone angle instead of the conventional real-time reconstruction. The reconstruction method considering the cone angle is applicable when the reconstruction speed is sufficiently high. As a reconstruction method considering the cone angle, for example, SyncRecon reconstruction (a method of reconstructing an image of a certain quality in synchronization with scanning) can be used.

  Note that when the reconstruction method considering the cone angle is used, it is not necessary to switch the reconstruction as in the present embodiment. However, in the case of SyncRecon reconstruction, there are limitations on the image thickness and the number of imaging columns, and therefore the method of this embodiment is used when such limitations cannot be allowed.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Mount apparatus, 2 ... Operation console, 3 ... Bed apparatus, 4 ... Top plate, 10 ... X-ray tube, 11 ... X-ray detector, 12 ... Aperture, 13 ... High pressure generation part, 14 ... Aperture drive device 15 ... Rotation drive device, 16 ... data collection unit, 17 ... gantry control unit, 20 ... input device, 21a ... scan condition setting unit, 21b ... condition change unit, 22 ... console control unit, 23 ... pre-processing unit, 24 ... projection data Storage unit, 25: reconstruction processing unit, 26: image storage unit, 27: image processing unit, 28: display device, P: subject.

Claims (4)

An X-ray tube that emits X-rays;
A bed having a top plate on which the subject is placed;
An X-ray detector for detecting the X-ray transmitted through the subject;
Setting means for setting scanning conditions including the scanning range of the helical shuttle;
A scanning unit that reciprocates the top plate in the body axis direction of the subject while rotating the X-ray tube around the subject based on the scanning condition;
A volume reconstruction unit that reconstructs volume of tomographic image data based on projection data acquired from an output signal of the X-ray detector with respect to positions at both ends of the scan range;
A real-time reconstruction unit that reconstructs tomographic image data in real time based on projection data acquired from an output signal of the X-ray detector, with respect to an intermediate position sandwiched between the positions of the both ends;
A display unit for displaying the tomographic image data reconstructed by the volume reconstruction unit or the real-time reconstruction unit;
Comprising
The scan condition includes the scan range, a reconstruction time Tv required for the volume reconstruction, a pause time Ts during the stop of the top plate, and the tomographic image after the top plate is moved again from the stop. And the maximum time Tn at which data may not be displayed,
The setting means includes
A determination unit for determining whether the reconstruction time Tv, the pause time Ts, and the maximum time Tn satisfy a relationship of Tv <Ts or a relationship of Tv−Ts ≦ Tn, respectively.
As a result of the determination, if any of the relations is satisfied, the scan condition is set, and a sending unit that sends the scan condition to the scan unit;
A computed tomography apparatus comprising: an output unit that outputs a message indicating that the pause time Ts cannot be set when the determination result is NO. The computed tomography apparatus according to claim 1,
The message represents an inability to set the pause time Ts and an inquiry about whether or not the pause time Ts can be changed.
The setting means includes
A pause time changing unit that controls to change the value of the pause time Ts to Tv−Tn and to re-execute the determination unit upon receiving an input to change the pause time Ts after the output of the message; ,
A computer tomography apparatus comprising: The computed tomography apparatus according to claim 1 or 2,
While receiving the tomographic image data reconstructed by the volume reconstruction unit, when receiving an input of a scan range after the next reciprocation, the input of the current scan range is accepted after the next reciprocation A scan range changing unit that instructs the scan unit to change to a scan range;
A computer tomography apparatus comprising: The computed tomography apparatus according to any one of claims 1 to 3,
The real-time reconstruction unit pauses during the operation of the volume reconstruction unit,
The volume reconstruction unit is a computed tomography apparatus that pauses during operation of the real-time reconstruction unit.

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