JP2011004980A - X-ray ct apparatus and movement control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus and a movement control program with further heightened safety.SOLUTION: This X-ray CT apparatus 100 obtains an image of a subject P placed on a top plate 22. Then, a mathematical expression model showing the shape on the top plate 22 of the subject P is created from the obtained image, and the interlock control (sub) for controlling the moving range of the top plate 22 is conducted using the created mathematical expression model. The X-ray CT apparatus 100 concurrently conducts the interlock control (regular) for controlling the moving range of the top plate 22 using information showing the positional relationship between a frame device 10 and the top plate 22. For example, the X-ray CT apparatus 100 displays warning information on a display part 32 when a moving designation for the top plate 22 received from an operator is determined to exceed an allowable moving range of the interlock control (sub), and stops the interlock control (sub) and conducts only the interlock control (regular) when a moving designation is further received from the operator in response to the warning information.

Description

  The present invention relates to an X-ray CT apparatus and a movement control program.

  2. Description of the Related Art In recent years, a bed of an X-ray CT (Computed Tomography) apparatus has a mechanism that moves back and forth, up and down, and left and right. For example, when the operator inputs a movement instruction to the X-ray CT apparatus for the purpose of aligning the region of interest (ROI) of the patient placed on the top plate with the center of the image, the bed follows the movement instruction. Moving.

  Here, the movement instruction by the operator may be input from an operation panel provided in the gantry of the X-ray CT apparatus or may be input from a console apparatus installed in a separate room or the like. When input from the operation panel, the operator can input a movement instruction while visually confirming the safety of the patient, but when input from the console device, the dome of the gantry is reflected on the screen of the console device. Therefore, it is difficult for the operator to visually confirm the safety of the patient.

  For this reason, conventionally, an X-ray CT apparatus that limits the movement range of the bed using the shape of the gantry, the shape of the bed, and their positional relationship has been proposed (Patent Document 1, etc.).

JP 2008-183220 A

  However, the above-described conventional technique has a problem that safety cannot be sufficiently improved. That is, the conventional technique limits the movement range of the bed using the shape of the gantry, the shape of the bed, and the positional relationship between them, and controls the body regardless of the patient's body shape, body position, and the like. In this regard, actually, imaging of patients with various body types, imaging with various body postures, and the like are performed, and there are cases where the control by the conventional technology cannot cope with it.

  The present invention has been made in view of the above, and an object of the present invention is to provide an X-ray CT apparatus and a movement control program capable of further improving safety.

  In order to solve the above-described problems and achieve the object, an X-ray CT apparatus according to claim 1 includes an image acquisition unit that acquires an image of a subject placed on a top board, and the image acquisition unit. From the acquired image, a subject model creating means for creating a mathematical model indicating the shape of the subject on the top plate, and a range of movement of the top plate using the mathematical model created by the subject model creating means And a movement control means for controlling the movement.

  In addition, the movement control program according to claim 7 includes: an image acquisition procedure for acquiring an image of a subject placed on a top plate; and an image acquired by the image acquisition procedure on a top plate of the subject. Causing the computer to execute a subject model creation procedure for creating a mathematical model indicating the shape of the object and a movement control procedure for controlling the movement range of the top board using the mathematical model created by the subject model creation procedure It is characterized by.

  According to the first or seventh aspect of the present invention, there is an effect that safety can be further improved.

FIG. 1 is a block diagram illustrating the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 2 is a diagram for explaining the movement of the top board. FIG. 3 is a block diagram illustrating a configuration of the gantry bed driving / scanning control unit. FIG. 4 is a diagram for explaining a mathematical model of a subject. FIG. 5 is a diagram for explaining the sub-interlock control. FIG. 6 is a diagram for explaining the sub-interlock control. FIG. 7 is a diagram for explaining the normal interlock control. FIG. 8 is a flowchart showing an example of an imaging preparation procedure for imaging using the X-ray CT apparatus. FIG. 9 is a flowchart showing the sub interlock control. FIG. 10 is a flowchart showing the normal interlock control.

  Hereinafter, embodiments of an X-ray CT apparatus and a movement control program according to the present invention will be described in detail. In addition, this invention is not limited by the following examples.

[Outline of X-ray CT Apparatus According to Embodiment 1]
First, an outline of the X-ray CT apparatus according to the first embodiment will be described. The X-ray CT apparatus according to the first embodiment creates a mathematical model indicating the shape of the subject on the top plate from the image of the subject placed on the top plate, and uses the created mathematical model to create a mathematical model of the top plate. Control the range of movement. In the first embodiment, such control is referred to as “virtual interlock control” or “sub interlock control”.

  The X-ray CT apparatus according to the first embodiment also performs interlock control for controlling the moving range of the top plate using only information indicating the positional relationship between the gantry and the top plate. In the first embodiment, such control based on the geometry of the apparatus is referred to as “normal interlock control”. The “secondary interlock control” plays a role of supplementing a portion that cannot be considered in the “primary interlock control”.

  As described above, since the X-ray CT apparatus according to the first embodiment controls the movement range of the top plate based on the shape of the subject on the top plate, imaging of patients with various body types and various postures are possible. It becomes possible to cope with photography and the like, and it becomes possible to further improve safety.

[Configuration of X-ray CT Apparatus According to Embodiment 1]
Next, the configuration of the X-ray CT apparatus according to the first embodiment will be described with reference to FIGS. FIG. 1 is a block diagram illustrating the configuration of the X-ray CT apparatus according to the first embodiment.

  As shown in FIG. 1, the X-ray CT apparatus 100 according to the first embodiment includes a gantry device 10, a couch device 20, and a console device 30.

  The couch device 20 is a table on which the subject P to be imaged is placed, and includes a couch driving unit 21 and a top plate 22. The top plate 22 is a plate on which the subject P is placed. The bed driving unit 21 moves the top plate 22 by driving a motor. Specifically, it moves in the direction toward the gantry device 10 (hereinafter referred to as “IN direction”) and in the opposite direction (hereinafter referred to as “OUT direction”), the up-down direction, and the left-right direction. In addition, the position information of the top plate 22 moved by the bed driving unit 21 is sent to a gantry bed driving / scanning control unit 33 described later.

  The top plate 22 moves as shown in FIG. 2, for example. FIG. 2 is a diagram for explaining the movement of the top board. As shown in FIG. 2, when the operator inputs a movement instruction to the input unit 31 described later for the purpose of aligning the ROI of the subject P placed on the top 22 with the center of the image, the top 22 is Move according to the movement instructions. In particular, a small ROI such as a heart leads to an improvement in image quality and a reduction in X-ray exposure by matching the center of the image, and thus the top plate 22 is often moved.

  The gantry device 10 is a device that irradiates the subject P with X-rays, detects X-rays that have passed through the subject P, and outputs the X-rays to the console device 30. An X-ray detector 13, a data collection unit 14, a rotating frame 15, and a gantry driving unit 16 are included.

  The high voltage generator 11 supplies a high voltage to the X-ray tube 12. The X-ray tube 12 is a vacuum tube and generates X-rays by a high voltage supplied from the high voltage generator 11. The X-ray detector 13 detects X-rays that have passed through the subject P. The data collection unit 14 generates projection data using the X-rays detected by the X-ray detector 13. The rotating frame 15 is an annular frame that supports the X-ray tube 12 and the X-ray detector 13 so as to face each other with the subject P interposed therebetween, and rotates at high speed and continuously. The gantry driving unit 16 rotates the rotary frame 15 by driving the motor, and rotates the X-ray tube 12 and the X-ray detector 13 on a circular orbit around the subject P.

  The console device 30 accepts an operation of the X-ray CT apparatus 100 by the operator and reconstructs an image from the projection data collected by the gantry device 10. Specifically, the console device 30 includes an input unit 31, a display unit 32, a gantry bed drive / scan control unit 33, an image processing unit 37, an image storage unit 38, and a system control unit 39.

  The input unit 31 is a mouse, a keyboard, or the like, and is used by an operator to input instructions to the X-ray CT apparatus 100. For example, the input unit 31 accepts setting of shooting conditions and accepts setting of ROI. In addition, the input unit 31 receives an instruction to move the top plate 22.

  The display unit 32 is a display such as an LCD (Liquid Crystal Display) and displays various types of information. For example, the display unit 32 displays an image stored in the image storage unit 38, a GUI (Graphical User Interface) for receiving various instructions from the operator, and the like.

  The system control unit 39 controls the entire X-ray CT apparatus 100 by controlling the gantry device 10, the couch device 20, and the console device 30. For example, the system control unit 39 controls the gantry bed drive / scan control unit 33 to collect projection data, and controls the image processing unit 37 to reconstruct an image from the projection data. When the system control unit 39 receives an instruction to move the top plate 22 from the operator, the system control unit 39 controls the gantry bed driving / scanning control unit 33 to move the top plate 22.

  The image processing unit 37 performs various processes on the projection data generated by the data collection unit 14. Specifically, the image processing unit 37 performs preprocessing such as sensitivity correction on the projection data generated by the data collection unit 14 and reconstructs an image based on the reconstruction condition instructed from the system control unit 39. Then, the reconstructed image is stored in the image storage unit 38.

  The gantry bed driving / scanning control unit 33 controls the high voltage generation unit 11, the data collection unit 14, and the gantry driving unit 16 based on the imaging conditions instructed by the system control unit 39 under the control of the system control unit 39. Further, the gantry bed driving / scanning control unit 33 controls the bed driving unit 21 based on an instruction to move the couchtop 22 instructed by the system control unit 39 under the control of the system control unit 39.

  Here, the configuration of the gantry bed driving / scanning control unit 33 will be described in detail with reference to FIG. FIG. 3 is a block diagram illustrating a configuration of the gantry bed driving / scanning control unit.

  As shown in FIG. 3, the gantry bed drive / scan control unit 33 includes a gantry drive control unit 34, a bed drive control unit 35, and a scan control unit 36. The gantry drive control unit 34 controls the gantry drive unit 16 based on the imaging conditions instructed from the system control unit 39. The scan control unit 36 controls the high voltage generation unit 11 and the data collection unit 14 based on the imaging conditions instructed from the system control unit 39.

  The bed driving control unit 35 includes a subject image acquisition unit 35a, a subject model creation unit 35b, a sub-interlock control unit 35c, and a primary interlock control unit 35d.

  The subject image acquisition unit 35a acquires an image of the subject P placed on the top board 22. Specifically, in Example 1, it is assumed that a conventional scan (a conventional scan refers to a non-helical scan) is performed for the purpose of acquiring an image for creating a mathematical model of the subject P. ing. Therefore, the subject image acquisition unit 35a acquires the conventional scan image stored in the image storage unit 38 via the system control unit 39 and sends it to the subject model creation unit 35b.

  The subject model creation unit 35b creates a mathematical model indicating the shape of the subject P on the top board 22. Specifically, the subject model creation unit 35b analyzes the conventional scan image sent from the subject image acquisition unit 35a and creates a rectangular model as a mathematical model of the subject P. In addition, the subject model creation unit 35b sends the created mathematical model of the subject P to the sub-interlock control unit 35c.

  Here, the mathematical model of the subject P will be described with reference to FIG. FIG. 4 is a diagram for explaining a mathematical model of a subject. In Example 1, the left-right direction of the top plate 22 is defined as the x-axis, and the up-down direction is defined as the y-axis. When the subject model creation unit 35b receives a conventional scan image as shown in FIG. 4 from the subject image acquisition unit 35a, the subject model creation unit 35b analyzes it using a known technique, and a region corresponding to the subject P and a region corresponding to air. And are separated. Next, the subject model creation unit 35b obtains the longest length “2J” in the x-axis direction and the longest length “K” in the y-axis direction for the region corresponding to the subject P. In this way, the subject model creation unit 35b creates a vertical model of K × 2J as a mathematical model indicating the shape of the subject P on the top board 22.

  Returning to FIG. 3, the sub-interlock control unit 35 c controls the movement range of the top 22 using the mathematical model of the subject P. Specifically, the secondary interlock control unit 35c performs secondary interlock control using the mathematical model of the subject P sent from the subject model creation unit 35b.

  Here, the sub-interlock control will be described with reference to FIGS. 5 and 6 are diagrams for explaining the sub-interlock control. As shown in FIG. 5, in the first embodiment, the horizontal direction of the top plate 22 is defined as the x axis, the vertical direction is defined as the y axis, and the IN / OUT directions are defined as the z axis. Further, the z axis is defined so as to pass through the center of the side surface on the opposite side of the gantry device 10 among the side surfaces of the bed apparatus 20, and the point where the z axis intersects the floor surface is defined as the origin of each axis.

Further, as constants, the height to the dome center of the gantry device 10 is “a”, the radius of the dome is “R _D ”, the length of the top plate 22 in the x-axis direction is “2L”, the top plate 22 and the dome A clearance guaranteed value in the x-axis direction and the y-axis direction between the two is “C _D ”. Note that the clearance guaranteed value C _D, sets the 25mm a forward cheating safety guaranteed in IEC60601-1-2, which is defined in International Electrotechnical Commission (International Electrotechnical Commission). “X _L ” is position information of the top plate 22 in the x-axis direction. A positive value indicates the amount of movement in the right direction, and a negative value indicates the amount of movement in the left direction. Although not shown in FIG. 5, “H” is position information of the top plate 22 in the y-axis direction.

  Now, the secondary interlock control unit 35c performs the secondary interlock control mainly by calculation using two mathematical expressions. This formula will be described with reference to FIG. The circle shown in FIG. 6 shows the dome of the gantry device 10, and the rectangle shown in FIG. 6 shows the mathematical model of the subject P created by the subject model creation unit 35b. The black rectangle shown indicates the top plate 22.

  It is assumed that the operator inputs a movement instruction to the input unit 31 and the top plate 22 moves to the position shown in FIG. 6 according to the movement instruction. As described above, “a” is the height to the dome center of the gantry device 10, and “H” is the position information of the top plate 22 in the y-axis direction. Therefore, the length of the rectangular model in the vertical direction is, as shown in FIG. 6, on the xy plane, a portion “aH” located below the dome center and a portion “above the dome center” "K- (a-H)".

On the other hand, “X _L ” is position information of the top plate 22 in the x-axis direction. Therefore, the portion located to the right of the dome center in the lateral length of the rectangular model can be indicated as “J + X _L ”. Then, using the Pythagorean theorem and the radius “R _D ” of the dome, the distance between the upper right corner of the rectangular model and the dome, and the distance between the lower right corner of the rectangular model and the dome are shown in FIG. Calculated as shown. In this way, the secondary interlock control unit 35c performs the secondary interlock control by the following two equations that compare these distances with the clearance guaranteed value “C _D ”.

Specifically, when the sub interlock control unit 35c receives the position information (x = X _L , y = H) of the top plate 22 from the bed driving unit 21, it determines whether or not the expression (1) is true. judge.

If it is not, the sub interlock control unit 35c has a top plate 22, upward or lateral direction (however, X _L of the code in the same direction only) to move to be construed longer than the allowable movement range As a certain (interlock detection), the couch driving unit 21 is controlled to stop the movement in the same direction, and warning information for warning that the upward or leftward movement no longer exceeds the allowable movement range is displayed on the display unit. 32. In addition, the sub interlock control part 35c in Example 1 displays warning information on the display part 32, and also displays the consent button which receives the consent by an operator.

Similarly, the secondary interlock control unit 35c determines whether or not the expression (2) is true.

If not, the sub-interlock control unit 35c moves the top plate 22 in the downward direction or the left-right direction (however, only in the same direction as the sign of X _L ) that is beyond the allowable movement range. As a certain (interlock detection), the couch driving unit 21 is controlled to stop the movement in the same direction, and warning information for warning that the movement in the downward direction or the horizontal direction is no longer within the allowable movement range is displayed on the display unit. 32. In addition, the sub interlock control part 35c in Example 1 displays warning information on the display part 32, and also displays the consent button which receives the consent by an operator.

  On the other hand, when the expression (2) is true, the sub interlock control unit 35c ends the sub interlock control for the position information of the top plate 22 received from the couch driving unit 21, and newly generates the couch driving unit. 21 shifts to sub-interlock control for the position information of the top plate 22 received from 21.

  That is, when the operator inputs a movement instruction to the input unit 31 and the top board 22 moves in accordance with the movement instruction, the position information of the top board 22 is sent from the couch driving unit 21 to the sub interlock control unit 35c each time. Therefore, as long as the top plate 22 continues to move, the secondary interlock control unit 35c continues the secondary interlock control using the equations (1) and (2). The sub-interlock control unit 35c performs the determination based on the expression (1) (determination as to whether the upper corner collides) and the determination according to the expression (2) (determination as to whether the lower angle collides) in parallel processing. .

  Returning to FIG. 3, the primary interlock control unit 35 d controls the movement range of the top plate 22 using information indicating the positional relationship between the gantry device 10 and the top plate 22. Here, the primary interlock control unit 35d and the secondary interlock control unit 35c independently perform interlock control. However, the primary interlock control by the primary interlock control unit 35d has priority over the secondary interlock control by the secondary interlock control unit 35c. That is, when the primary interlock control unit 35d detects the interlock, the movement of the top plate 22 is stopped even if the secondary interlock control unit 35c does not detect the interlock.

Here, the normal interlock control will be described with reference to FIG. FIG. 7 is a diagram for explaining the normal interlock control. As already described, the height to the dome center of the gantry device 10 is “a”, and the position information of the top plate 22 in the y-axis direction is “H”. Further, as shown in FIG. 7, as a constant, the length of the top plate 22 in the z-axis direction is “T”, the distance between the rear end of the bed apparatus 10 and the front end of the gantry apparatus 10 is “D”, and the top plate 22 The clearance guaranteed value in the z-axis direction between the gantry 10 and the gantry device 10 is “C _G ”. Note that the clearance guaranteed value C _G, sets a 25mm a forward cheating safety guaranteed in IEC60601-1-2, which is defined in International Electrotechnical Commission. “Z _C ” is position information of the top plate 22 in the z-axis direction. A positive value indicates the amount of movement in the IN direction, and a negative value indicates the amount of movement in the OUT direction. Although not shown in FIG. 7, “H _UP-LIMIT ” is the upper limit of the top plate 22, and “H _DOWN-LIMIT ” is the lower limit of the top plate 22, “X _{RIGHT-LIMIT”.} “Is the limit in the right direction of the top plate 22, and“ X _LEFT-LIMIT ”is the limit in the left direction of the top plate 22.

The primary interlock control unit 35d performs the primary interlock control mainly by calculation using four mathematical expressions. Specifically, when the primary interlock control unit 35d receives the position information (x = X _L , y = H, z = Z _C ) of the top plate 22 from the bed driving unit 21, first, the equation (3) is expressed. Determine if true.

  If true, the primary interlock control unit 35d determines that the top plate 22 is outside the dome, terminates the positive interlock control for the position information of the top plate 22 received from the bed driving unit 21, and newly The process proceeds to the normal interlock control for the position information of the top board 22 received from the bed driving unit 21.

On the other hand, if the answer is no, the primary interlock control unit 35d continues to assume that the top plate 22 is inserted into the dome or is approaching the dome until the clearance guarantee value C _G or less is reached. Thus, it is determined whether or not the expression (4) is true.

If not, the primary interlock control unit 35d moves the top plate 22 in the downward direction or the left-right direction (however, only in the same direction as the sign of X _L ) that is beyond the allowable movement range. As a certain (interlock detection), the bed driving unit 21 is controlled to stop the movement in the same direction.

On the other hand, if the expression (4) is true, the primary interlock control unit 35d then determines whether the expression (5) is true, and if not, the top plate 22 is determined. Is moved beyond the allowable movement range (interlock detection), the bed driving unit 21 is controlled to stop the movement in the same direction.

Two cases are possible as the case of no. That is, when “H _UP-LIMIT ” is exceeded, the primary interlock control unit 35d controls the bed driving unit 21 to stop the upward movement. On the other hand, when the value falls below “H _DOWN-LIMIT ”, the normal interlock control unit 35 d controls the bed driving unit 21 to stop the downward movement.

Similarly, the positive interlock control unit 35d determines whether or not the expression (6) is true, and if not, it is no longer possible to move the table 22 in the left-right direction to set an allowable movement range. The bed driving unit 21 is controlled to stop moving in the same direction as exceeding (interlock detection).

Two cases are possible as the case of no. That is, when “X _RIGHT-LIMIT ” is exceeded, the primary interlock control unit 35d controls the bed driving unit 21 to stop moving in the right direction. On the other hand, when the value is lower than “X _LEFT-LIMIT ”, the normal interlock control unit 35d controls the bed driving unit 21 to stop the movement in the left direction. The positive interlock control unit 35d performs the determination by the expression (5) (determination of vertical movement) and the determination by the expression (6) (determination of horizontal movement) by parallel processing.

[Processing Procedure by X-ray CT Apparatus According to Embodiment 1]
Next, a processing procedure performed by the X-ray CT apparatus according to the first embodiment will be described with reference to FIGS. FIG. 8 is a flowchart showing an example of an imaging preparation procedure for imaging using the X-ray CT apparatus. FIG. 9 is a flowchart showing the secondary interlock control, and FIG. 10 is a flowchart showing the primary interlock control.

[Shooting preparation procedure]
As shown in FIG. 8, in the first embodiment, the imaging preparation procedure starts with patient setup (step S101). Specifically, for example, the operator performs a local operation on an operation panel provided in the gantry device 10 to align the subject P, or performs a setup for injecting a contrast agent.

  Next, scano imaging is performed (step S102). For example, the operator performs scano imaging on the xz plane.

  Then, ROI setting is performed on the scanogram (step S103). For example, the operator sets ROI near the heart of the subject P in the scanogram taken in step S102.

  Next, a conventional scan is performed (step S104). For example, the operator performs a conventional scan on the xy plane for the purpose of acquiring an image for creating a mathematical model of the subject P. The conventional scan image is stored in the image storage unit 38. Note that a low dose is sufficient for the X-ray conditions in this case. The maximum size of FOV (Field Of View) is desirable.

  Then, a rectangular model is created as a mathematical model of the subject P (step S105). For example, the subject image acquisition unit 35a acquires a conventional scan image stored in the image storage unit 38 via the system control unit 39, and the subject model creation unit 35b is sent from the subject image acquisition unit 35a. A conventional scan image is analyzed, and a rectangular model is created as a mathematical model of the subject P.

  Next, ROI setting in a conventional scan image is performed (step S106). For example, the operator sets ROI of the heart region of the subject P in the conventional scan image taken in step S104.

  Then, alignment of the subject P by remote operation is started (step S107). For example, when the operator inputs a movement instruction to the input unit 31 of the console device 30, the subject P is positioned by remote operation. The movement instruction input to the input unit 31 by the operator is sent to the couch driving unit 21 via the system control unit 39 and the couch driving / scanning control unit 33, and the couch driving unit 21 is controlled so that the top plate 22 is moved. Moving.

  Then, interlock control is performed (step S108). That is, the position information of the top plate 22 moved by the bed driving unit 21 is sent to the gantry bed driving / scanning control unit 33 each time. Then, the secondary interlock control by the secondary interlock control unit 35c and the primary interlock control by the primary interlock control unit 35d are performed.

  After that, until the alignment by the remote operation is completed (No at Step S109), the interlock control is continuously performed. For example, when the operator completes the alignment by pressing the end button (Yes at Step S109). A series of shooting preparation procedures is completed. Thereafter, injection of a contrast medium, real prep scan, and the like are performed, and then arbitrary imaging such as dynamic volume scanning, wide volume scanning, and helical scanning is performed, and imaging is completed.

[Secondary interlock control]
Next, the secondary interlock control by the secondary interlock control unit 35c will be described with reference to FIG. It is assumed that the operator inputs a movement instruction to the input unit 31 and the top plate 22 has moved according to the movement instruction. Then, the sub interlock control unit 35c acquires the position information (x = X _L , y = H) of the top plate 22 from the bed driving unit 21 (step S201).

Then, the sub interlock control unit 35c determines whether or not the expression (1) is true (step S202).

If a not (step S202 negative), the sub interlock control unit 35c has a top plate 22, upward or lateral direction (however, X _L of the code in the same direction only) no longer allowable moving to move the The bed driving unit 21 is controlled to stop the movement in the same direction as exceeding the range (interlock detection) (step S203).

  Further, the sub-interlock control unit 35c displays warning information for warning that the upward or leftward movement no longer exceeds the allowable movement range and an approval button for accepting the approval by the operator on the display unit 32 ( Step S204).

  Then, the secondary interlock control unit 35c determines whether or not the approval button has been pressed (step S205), and if it has been pressed (Yes in step S205), the secondary interlock control function is stopped (step S205). Step S206). That is, only the primary interlock control unit 35d is controlled, and the top plate 22 can continue to move until the interlock is detected by the primary interlock control unit 35d. On the other hand, when there is no depression (No at Step S205), no further operation instruction in the interlock direction is accepted, and the top panel 22 can move only in the direction to avoid the interlock.

Similarly, the sub interlock control unit 35c determines whether or not the expression (2) is true (step S207). That is, the sub interlock control unit 35c performs the determination in step S202 and the determination in step S207 in parallel processing.

If a not (step S207 negative), the sub interlock control unit 35c has a top plate 22, downward or horizontal direction (where, X _L of the code in the same direction only) to move to no longer allowable movement The bed driving unit 21 is controlled so as to stop the movement in the same direction as exceeding the range (step S208). Thereafter, similarly to the above, warning information and an approval button are displayed (step S204).

  In addition, when (1) Formula is true in step S202 (step S202 affirmation) and (2) Formula is true in step S207 (step S207 affirmation), the sub interlock control part 35c drives a bed earlier. The sub-interlock control for the position information of the top plate 22 received from the unit 21 is terminated, and the process proceeds to the sub-interlock control for the position information of the top plate 22 newly received from the bed driving unit 21.

[Normal interlock control]
Next, the primary interlock control by the primary interlock control unit 35d will be described with reference to FIG. It is assumed that the operator inputs a movement instruction to the input unit 31 and the top plate 22 has moved according to the movement instruction. Then, the primary interlock control unit 35d acquires the position information (x = X _L , y = H, z = Z _C ) of the top plate 22 from the bed driving unit 21 (step S301).

Then, the primary interlock control unit 35d determines whether or not the expression (3) is true (step S302).

  If true (Yes in step S302), the primary interlock control unit 35d assumes that the top plate 22 is outside the dome and performs positive interlock control on the position information of the top plate 22 received from the bed driving unit 21. The process proceeds to the normal interlock control for the position information of the top plate 22 newly received from the bed driving unit 21.

On the other hand, if it is not (step S302 negative), the positive interlock control unit 35d is intended to top plate 22 is approaching the dome until either is inserted into the dome, or following clearance guaranteed value C _G Then, it is determined whether or not the equation (4) is true (step S303).

If a not (step S303 negative), the positive interlock control unit 35d includes a top plate 22, downward or horizontal direction (where, X _L of the code in the same direction only) to move to no longer allowable movement The bed driving unit 21 is controlled so as to stop the movement in the same direction as being beyond the range (step S304).

On the other hand, if the expression (4) is true (Yes at Step S303), then the primary interlock control unit 35d determines whether the Expression (5) is true (Step S305).

  If not (No in step S305), the normal interlock control unit 35d stops moving in the same direction on the assumption that moving the top 22 in the vertical direction is beyond the allowable movement range. The couch driving unit 21 is controlled to do so (step S306).

Similarly, the primary interlock control unit 35d determines whether or not the expression (6) is true (step S307). That is, the primary interlock control unit 35d performs the determination in step S305 and the determination in step S307 in parallel processing.

  If not (No in step S307), the normal interlock control unit 35d stops moving in the same direction on the assumption that moving the table 22 in the left-right direction is beyond the allowable movement range. The couch driving unit 21 is controlled to do so (step S308).

  When the expression (5) is true in step S305 (Yes in step S305) and in the case where the expression (6) is true in step S307 (Yes in step S307), the positive interlock control unit 35d The normal interlock control for the position information of the top plate 22 received from the driving unit 21 is terminated, and the process proceeds to the normal interlock control for the position information of the top plate 22 newly received from the bed driving unit 21.

[Effect of Example 1]
As described above, in the X-ray CT apparatus 100 according to the first embodiment, the subject image acquisition unit 35a acquires an image of the subject P placed on the top board 22, and the subject model creation unit 35b Then, a mathematical model indicating the shape of the subject P on the top 22 is created from the image obtained by the subject image obtaining unit 35a. Further, the sub interlock control unit 35c controls the movement range of the top board 22 using the mathematical model created by the subject model creation unit 35b.

  As described above, since the X-ray CT apparatus 100 according to the first embodiment controls the movement range of the top plate 22 based on the shape of the subject P on the top plate 22, imaging of various body types of patients and various It is possible to cope with photographing with a proper posture, and it is possible to further improve safety. This is particularly effective when the patient has a large body shape, or when the body is placed sideways on the top plate 22, standing, or approaching either the left or right extreme.

  The X-ray CT apparatus 100 according to the first embodiment further includes a positive interlock control unit 35 d that controls the movement range of the top plate 22 using information indicating the positional relationship between the gantry device 10 and the top plate 22. The primary interlock control unit 35d controls the movement range of the top plate 22 in parallel with the secondary interlock control unit 35c. When the secondary interlock control unit 35c detects the secondary interlock while the primary interlock control unit 35d does not detect the primary interlock, the secondary interlock control unit 35c displays warning information. Only when the operator approves, the continuous operation in the sub-interlock detection direction is enabled. That is, only the primary interlock control unit 35d is controlled, and the top plate 22 can continue to move in the sub-interlock detection direction until the interlock is detected by the primary interlock control unit 35d.

  As described above, the X-ray CT apparatus 100 according to the first embodiment uses not only the secondary interlock control based on the shape of the subject P on the top plate 22 but also the positive interlock control based on the operator's approval. As a result, it is possible to increase not only safety but also flexibility.

  Now, as the first embodiment, after detecting the sub-interlock based on the shape of the subject P on the top 22, the method of switching only to the positive interlock control based on the operator's consent has been described. The present invention is not limited to this. That is, the primary interlock control and the secondary interlock control may be handled at the same level to control the movement range of the top board 22.

  In this case, the sub interlock control unit 35c determines that the movement instruction of the top plate 22 received from the operator exceeds the allowable movement range, and the bed driving unit 21 so as to stop the movement in the predetermined direction. Even if a movement instruction is further received from the operator after controlling the movement, it may be controlled not to follow the movement instruction. That is, even if the primary interlock control unit 35d does not detect the interlock, the movement of the top plate 22 is limited. Further, a local operation from the operation panel of the gantry device 10 may be accepted.

  In the first and second embodiments so far, when the operator inputs a movement instruction to the input unit 31 and the top plate 22 moves according to the movement instruction, the sub interlock control unit 35c is moved from the bed driving unit 21. The method of acquiring the position information of the top plate 22 and starting the sub interlock control has been described. However, the present invention is not limited to this. For example, when the movement arrival point of the top plate 22 is estimated in advance at the stage of ROI setting, the secondary interlock control unit 35c may stop moving, or the primary interlock control unit 35d may stop moving. May display warning information indicating that the ROI cannot be set at the center of the image on the display unit 32 in advance.

For example, in the ROI setting in step S106 shown in FIG. 8, when the ROI setting related to the subject P is received from the operator, the X-ray CT apparatus 100 assumes that the received ROI is set at the center of the image. Position information (x-axis position information “X _L ”, y-axis position information “H”) is estimated. Next, the X-ray CT apparatus 100 substitutes the estimated position information into the equations (1) to (6), and determines whether each equation is true. And when it is not true, since it is a case where it is determined that the estimated movement arrival point exceeds the allowable movement range, the X-ray CT apparatus 100 displays warning information indicating the determination content on the display unit 32. indicate. Note that the X-ray CT apparatus 100 accepts a remote operation as usual until actually exceeding the allowable movement range, and the subsequent interlock control can be controlled as in the first or second embodiment.

  In addition, as described in the first embodiment, after detecting the sub-interlock based on the shape of the subject P on the top 22, when switching to the primary interlock control based on the operator's approval, For example, in the normal interlock control, confirmation information for confirming whether or not to continue the movement may be displayed on the display unit 32 every time the predetermined movement range is moved. For example, after the primary interlock control unit 35d starts the primary interlock control, it stops every time it moves 1 cm and displays confirmation information on the display unit 32 to confirm whether or not to continue the movement. It may be controlled to continue the movement after accepting the pressing of the approval button.

[Image for creating mathematical model of subject P]
In the above-described embodiment, a method has been described in which a conventional scan is performed for the purpose of acquiring an image for creating a mathematical model of the subject P, and a mathematical model of the subject P is created from the conventional scan image. However, the present invention is not limited to this. For example, by changing the position of the X-ray tube and performing scanning imaging from two directions (dual scanning), information on vertical K and horizontal 2J necessary for creating a mathematical model of the subject P may be acquired. . That is, apart from the scan imaging that captures the xz plane for setting the ROI, for example, by performing scan imaging of the yz plane, information on the vertical K and horizontal 2J necessary for creating the mathematical model of the subject P is acquired. Can do. In this case, conventional scanning is not necessary.

  Further, by simplifying the mathematical model of the subject P and using, for example, a method of creating only from the horizontal 2J information, the subject model can be created only from the scanogram obtained by photographing the xz plane. For example, assuming the aspect ratio of the human body, the vertical K is calculated from the horizontal 2J information, and the mathematical model of the subject P using the horizontal 2J information that is an actual measurement value and the vertical K information that is an estimated value. Can also be created. In this case, it is not necessary to perform scano imaging from two directions.

[Mathematical model of subject P]
In the above embodiment, the method of creating a rectangular model as the mathematical model of the subject P has been described. However, the present invention is not limited to this. For example, an elliptic model may be created.

DESCRIPTION OF SYMBOLS 100 X-ray CT apparatus 10 Base apparatus 11 High voltage generation part 12 X-ray tube 13 X-ray detector 14 Data collection part 15 Rotating frame 16 Base drive part 20 Bed apparatus 21 Bed drive part 22 Top plate 30 Console apparatus 31 Input part 32 Display unit 33 Pedestal bed drive / scan control unit 34 Pedestal drive control unit 35 Couch drive control unit 36 Scan control unit 37 Image processor 38 Image storage unit 39 System control unit

Claims (7)

Image acquisition means for acquiring an image of the subject placed on the top;
From the image acquired by the image acquisition means, subject model creation means for creating a mathematical model showing the shape of the subject on the top plate;
An X-ray CT apparatus comprising: a movement control unit that controls a movement range of the top plate using a mathematical model created by the subject model creation unit. Further comprising second movement control means for controlling the movement range of the top board using information indicating the positional relationship between the gantry and the top board;
The second movement control means controls the movement range of the top plate in parallel with the movement control means,
When it is determined that the movement instruction of the top plate received from the operator exceeds the allowable movement range, the movement control means displays warning information for the movement instruction on the display unit, and responds to the warning information. The X-ray CT apparatus according to claim 1, wherein the control by the movement control unit is stopped when an approval is received from the operator.   The second movement control means displays confirmation information for confirming whether or not to continue the movement every time the movement control means stops the control by the movement control means, every time it moves within a predetermined movement range. The X-ray CT apparatus according to claim 2, wherein the X-ray CT apparatus is displayed on a screen.   When the movement control means determines that the movement instruction of the top plate received from an operator exceeds an allowable movement range, the movement control means controls the top board not to move according to the movement instruction. The X-ray CT apparatus according to claim 1.   When the movement control means receives a region-of-interest setting related to the subject from the operator, the movement control unit estimates a movement arrival point of the top plate from the region-of-interest setting, and the estimated movement arrival point exceeds an allowable movement range. The X-ray CT apparatus according to claim 1, wherein warning information indicating the determination content is displayed on the display unit when the determination is made. The image acquisition means acquires a cross-sectional image as an image of the subject,
The object model creation means analyzes the maximum value in the vertical direction and the maximum value in the horizontal direction of the shape from the cross-sectional image, and creates a rectangular model formed with the analyzed maximum value. Item 2. The X-ray CT apparatus according to Item 1. An image acquisition procedure for acquiring an image of the subject placed on the top;
From the image acquired by the image acquisition procedure, a subject model creation procedure for creating a mathematical model indicating the shape of the subject on the top board;
A movement control program for causing a computer to execute a movement control procedure for controlling a movement range of the top board using a mathematical model created by the subject model creation procedure.

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