Movable x-ray imaging device and control method thereof

Abstract

To prevent overturn of a movable X-ray imaging device having a telescopic arm even when an operator extends or turns an arm in an optional procedure.SOLUTION: For the purpose of stability of cart, an acceptable maximum arm length Lmax(θ) is obtained in advance per rotational angles of a support pillar. In the acceptable maximum arm length Lmax(θ), a shaft of the arm is set shorter when the shaft of arm corresponds to a short shaft direction of the cart than when the shaft corresponds to a longer shaft direction of the cart. When the current arm length Lr is not less than the acceptable maximum arm length Lmax(θ), the control part shrinks or extends the arm or applies a support pillar rotation brake to prevent a rotation of the support pillar.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an X-ray imaging apparatus capable of moving an apparatus.

Background Art

[0002] A mobile X-ray imaging apparatus called a mobile cart is known. The mobile X-ray imaging apparatus has a structure in which an X-ray imaging apparatus main body is mounted on a cart, and the X-ray generator is mounted at the tip of an arm. When moving, the arm can be folded to form a compact shape and placed on the cart. When in use, by expanding the arm, the tip of the arm can be extended long to the upper space of the subject on the bed, and the subject is irradiated with X-rays from the X-ray generator supported at the tip of the arm. Further, the arm can be rotated around the cart, and regardless of the position where the cart is placed with respect to the bed, the arm can be extended to place the X-ray generator above the subject.

[0003] However, the X-ray generator is heavy, and when the arm is expanded and extended, the cart may become unstable and fall over. Therefore, Patent Document 1 discloses a mobile X-ray imaging apparatus in which auxiliary legs are arranged at the lower part of the cart, and when the arm is extended, the auxiliary legs are projected outside the cart to prevent falling.

[0004] Further, Patent Document 2 discloses a technique for preventing falling by restricting the opening angle of a hinge when the hinge is opened in a mobile X-ray imaging apparatus having a structure in which a hinge is provided in the middle of an arm and the arm is expanded by opening the hinge, depending on the direction of the arm.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a mobile X-ray imaging apparatus having a telescopic arm, the following procedure may be used in actual clinical practice: while moving the cart, start extending the arm, determine the position of the cart while extending the arm, swing the arm toward the subject, and fully extend the arm to place the X-ray generator in the upper space of the subject. This shortens the time until the arm is extended to a state where imaging is possible. However, in a mobile X-ray imaging apparatus having a telescopic arm, since the cart and the X-ray imaging apparatus main body on the cart are generally rectangular parallelepiped in shape, when the arm is swung with the arm greatly extended, if the direction of the central axis of the arm coincides with the short axis direction of the X-ray imaging apparatus main body, there is a problem that it is likely to tip over.

[0007] An object of the present invention is to prevent tipping over in a mobile X-ray imaging apparatus having a telescopic arm, regardless of the procedure by which the operator extends or swings the arm.

Means for Solving the Problems

[0008] In order to achieve the above object, according to the present invention, there is provided a mobile X-ray imaging apparatus including a carriage, an X-ray imaging apparatus main body mounted on the carriage, a column, a telescopic arm having one end supported on a side surface of the column and capable of extending and contracting, an X-ray generator, and a control unit. The column has a lower end mounted on the carriage and is supported by the carriage so as to be rotatable about the central axis of the column. The X-ray generator is supported at the tip of the arm. The X-ray imaging apparatus main body has a long axis along the traveling direction and a short axis in the width direction. The control unit includes a storage unit in which a maximum allowable arm length Lmax(θ) allowed for the arm for the stability of the carriage, which is predetermined for each rotation angle θ of the column, is stored in advance. The maximum allowable arm length Lmax(θ) is shorter when the rotation angle θ is such that the axis of the arm coincides with the short axis direction than when the rotation angle θ coincides with the long axis. The column is provided with a rotation angle detector p for detecting the rotation angle θ and a column rotation brake for stopping the rotation of the column. The arm is provided with an arm length detector for detecting the current arm length L. The control unit takes in the rotation angle θ detected by the rotation angle detector and the current arm length L output by the arm length detector, and determines whether the arm length L is less than the maximum allowable arm length Lmax(θ) stored in the storage unit. When the arm length L is not less than the maximum allowable arm length Lmax(θ), the control unit either contracts the arm or turns on the column rotation brake to prevent the column from rotating.

Advantages of the Invention

[0009] According to the present invention, in a mobile X-ray imaging apparatus including a telescopic arm, it is possible to prevent the apparatus from tipping over even when an operator extends or turns the arm in any procedure, thus improving the convenience for the operator.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the X-ray irradiation apparatus according to the embodiment of the present invention will be described with reference to the drawings.

[0012] <<Embodiment 1>> The mobile X-ray imaging apparatus according to Embodiment 1 will be described. The mobile X-ray imaging apparatus according to Embodiment 1 takes into account that when the arm 5 is positioned in the short-axis direction 1b, the maximum length of the arm 5 at which the mobile X-ray imaging apparatus does not tip over is smaller than when the arm 5 is positioned in the long-axis direction 1a of the X-ray imaging apparatus main body 1. When the arm 5 is positioned in the short-axis direction 1b, the control unit 9 has a function of automatically expanding and contracting the electric arm 5-1.

[0013] First, the structure of the mobile X-ray imaging apparatus according to Embodiment 1 will be described with reference to FIGS. 1 to 7.

[0014] FIG. 1 is a side view of the mobile X-ray imaging apparatus with the arm retracted, and FIG. 2 is a side view of the mobile X-ray imaging apparatus with the arm rotated and extended forward. FIGS. 3 and 4(a) are top views of the mobile X-ray imaging apparatus with the arm rotated forward, FIGS. 4(b) and 4(c) are top views of the extended arm, and FIGS. 4(d) and 5 are views of the arm as seen from arrow A and an enlarged view thereof. FIG. 6 is a diagram for explaining the structure of the arm and the column, and FIG. 7 is a block diagram of the main configuration of the mobile X-ray imaging apparatus.

[0015] As shown in FIG. 1, the mobile X-ray imaging apparatus includes a carriage 81, an X-ray imaging apparatus main body 1, an X-ray generator 2, a telescopic arm 5, and a column 6 that supports the arm 5. A control unit 9 is disposed inside the X-ray imaging apparatus main body 1. The X-ray generator 2 is provided at the tip of the arm 5 and is supported by the arm 5. The X-ray imaging apparatus main body 1 and the arm 5 are mounted on the carriage 81. The carriage 81 is provided with front wheels 4 and a pair of rear wheels 8. The front wheels 4 may be a pair or a single wheel. Hereinafter, the direction in which the carriage 81 moves forward is referred to as the front, and the direction in which the carriage moves backward is referred to as the rear.

[0016] As shown in the top view of FIG. 3, the X-ray imaging apparatus main body 1 has a substantially rectangular parallelepiped shape, with the longitudinal axis direction 1a being the front-rear direction and the short axis direction 1b being the left-right direction (width direction).

[0017] As shown in FIG. 6, the central axes of the columns 6 are aligned in the vertical direction. The carriage is provided with a flange 6a at the lower end, and gears are formed on the outer periphery of the flange 6a. The flange 6a is inserted into the upper surface of the carriage 81. Inside the carriage 81, a gear 13 that meshes with the gear of the flange 6a, a support mechanism (not shown) that rotatably supports the column 6 about its central axis, and a column rotation brake 21-1 that stops the rotation of the column 6 are arranged. A potentiometer, for example, is arranged on the gear 13 as a rotation angle detector 14 that detects the rotation angle of the column 6.

[0018] Near the upper end of the column 6, an arm 5 is provided as shown in FIG. 6. The arm 5 includes a manual arm 5-1 and an electric arm 5-2 provided at its tip as shown in FIG. 6. The manual arm includes a cylindrical manual first arm 5-1a and a cylindrical manual second arm 5-1b inserted therein. One end of the cylindrical manual first arm 5-1a is fixed to the side surface of the column 6. Although a mechanism for moving the manual first arm 5-1a up and down is provided inside the column 6, the description of this mechanism is omitted here.

[0019] A pair of slide rails 5-3 are fixed to the inner wall of the manual first arm 5-1a along its axial direction. The outer periphery of the manual second arm 5-1b engages with the slide rails 5-3 and is movable in the axial direction. An arm brake 21-2 is arranged on the slide rail 5-3, and the arm brake 21-2 operates under the control of the control unit 9 to stop the operation of the manual second arm 5-1b.

[0020] Inside the manual second arm 5-1b, an electric arm 5-2 is arranged. On the electric arm 5-2, as a driving part, a ball screw 12 and a motor 11 for rotating the ball screw 12 are arranged. The operation of the motor 11 is controlled by the control unit 9. The electric arm 5-2 is provided with a through hole along its axial direction, and an internal thread is formed on the inner wall. The ball screw 12 is screwed with the internal thread of the electric arm 5-2. When the motor 11 rotates the ball screw 12, the electric arm 5-2 moves in the axial direction. An X-ray generator 2 is fixed to the tip of the electric arm 5-2.

[0021] Also, inside the manual first arm 5-1a, an arm length detector 10 is arranged to detect the current length (arm length Lr) of the arm 5. The arm length detector 10 includes a distance sensor that measures the distance L to the end of the electric arm 5-2 on the motor 11 side, and obtains the current arm length Lr of the arm 5 based on the measured distance L of the distance sensor.

[0022] As shown in FIG. 5, an X-ray movable aperture 3 is attached to the lower part of the X-ray generator 2. A pair of handles 17a, 17b are arranged on both side surfaces of the X-ray movable aperture 3 across the central axis of the arm 5. The pair of handles 17a, 17b are used when the operator grasps them to pull out the manual second arm 5-1b from the manual first arm 5-1a or turn the entire arm 5. Inside both handles 17a, 17b, brake release buttons 17-1 are arranged respectively. When the brake release button 17-1 is pressed, the control unit 9 can release both the column rotation brake 21-1 and the arm brake 21-2.

[0023] Therefore, when the operator grasps the handles 17a, 17b, by gripping and pressing the brake release button 17-1 together with the handles 17a, 17b, both the column rotation brake 21-1 and the arm brake 21-2 are released, the manual arm 5-1 can be extended / retracted, the column 6 can be rotated, and the arm 5 can be turned.

[0024] Also, among the pair of handles 17a and 17b, when viewed from the direction of arrow A in Fig. 4(a) of the X-ray generator 2, on the outer periphery of the handle 17a located on the left side, as shown in Figs. 4(d) and 5, an extension button 18 for extending the electric arm 5-2 is arranged. On the outside of the handle 17b located on the right side, a retraction button 19 for retracting the electric arm 5-2 is arranged. When the extension button 18 is pressed by the operator, the control unit 9 rotates the motor 11 in a predetermined direction that rotates the ball screw 12 in the direction in which the electric arm 5-2 is extended from the manual second arm 5-1b. On the other hand, when the retraction button 19 is pressed by the operator, the motor 11 is rotated in the reverse direction to retract the electric arm 5-2 into the manual second arm 5-1b.

[0025] Therefore, when the operator grasps the handles 17a and 17b, by holding and pressing the brake release button 17-1 together, as shown in Fig. 1, the arm 5 can be rotated around the support column 6 from the state where it is arranged on the upper part of the X-ray imaging apparatus main body 1 and supported by the catch column 7 arranged on the upper surface of the X-ray imaging apparatus main body 1, and directed forward of the X-ray imaging apparatus main body 1 as shown in Figs. 3 and 4(a). Further, when the operator manually pulls the handles 17a and 17b, as shown in Fig. 4(b), the manual second arm 5-1b can be pulled out from the manual first arm 5-1a to manually extend the arm 5. Also, by the reverse operation, the arm 5 can be manually retracted.

[0026] Furthermore, the operator can extend the electric arm 5-2 from the manual arm 5-1 by pressing the extension button 18 of the handle 17a to reach the states shown in Figs. 2 and 4(c). This state is the state where the arm 5 is extended to the maximum extent. When the desired length is reached, by releasing the hand from the extension button 18, the extension of the electric arm 5-2 can be stopped. Also, by pressing the retraction button 19 of the handle 17b, the electric arm 5-2 can be retracted.

[0027] Note that the manual arm 5-1 and the electric arm operate independently, and the operator can arbitrarily choose which one to operate first for extension / retraction.

[0028] Also, although not shown in the figure, a drive motor for rotating the rear wheels 8 to assist the traveling of the carriage 81 and a battery for supplying power to the drive motor are arranged inside the carriage 81. The drive motor may be respectively connected to a pair of rear wheels 8, or an axle connecting a pair of rear wheels 8 may be rotated by one drive motor. Here, only the rear wheels 8 are driven by the drive motor for rotation, but the front wheels 4 may be driven for rotation.

[0029] The X-ray imaging apparatus main body 1 is provided with a handle 37 as shown in FIG. 1. The handle 37 is provided with a switch. When the operator presses the handle 37, the switch is turned on, the drive motor is driven, and the rear wheels 8 are driven to move the mobile X-ray imaging apparatus.

[0030] The X-ray generator 2 incorporates an X-ray tube that irradiates X-rays toward the subject and a high-voltage generator. The operations of the X-ray generator 2 and the X-ray aperture 103a are controlled by the arranged control unit 9. Note that the high-voltage generator may not be incorporated in the X-ray generator 2 and may be arranged separately.

[0031] During imaging, the mobile X-ray imaging apparatus continuously irradiates the subject with X-rays from the X-ray generator 2 under the control of the control unit 9. A detection signal is received by an image generation unit (not shown) in the control unit 9 from an X-ray detector (FPD: flat panel detector, etc.) arranged under the subject through wireless or wired communication. The image generation unit generates an X-ray image and displays it on a display device (not shown) provided on the upper surface or the like of the X-ray imaging apparatus main body 1.

[0032] On the other hand, as shown in FIG. 7, the control unit 9 includes a decision-making unit 22, a stability determination unit 15, an Lmax storage unit 36, a brake release unit 20, and a motor control unit 16.

[0033] The control unit 9 is composed of a computer or the like equipped with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and a memory. The CPU reads and executes a program stored in the memory (storage unit), thereby realizing the functions of the decision-making unit 22, the stability determination unit 15, the brake release unit 20, and the motor control unit 16. Further, the Lmax storage unit 36 is provided in the memory (storage unit) within the control unit 9.

[0034] Note that part or all of the control unit 9 can be configured by hardware. For example, circuit design can be performed using a custom IC such as an ASIC (Application Specific Integrated Circuit) or a programmable IC such as an FPGA (Field-Programmable Gate Array) to realize the functions of the above-mentioned respective units.

[0035] Also, in the present embodiment, as shown in FIG. 8, the maximum allowable arm length Lmax(θ) allowed for the arm 5 is obtained in advance for each rotation angle θ of the arm 5 so that extending the arm 5 does not cause the mobile X-ray imaging apparatus to fall over.

[0036] As can be seen from FIG. 8, since the X-ray imaging apparatus main body 1 mounted on the carriage 81 has a rectangular parallelepiped shape, when the rotation angle θ of the support column 6 is set in the direction in which the axis of the arm 5 coincides with the long axis direction 1a (front-rear direction) of the X-ray imaging apparatus main body 1, even if the manual first arm 5-1a, the manual second arm 5-1b, and the electric arm 5-2 of the arm 5 are all set to the most extended state (maximum arm length Lb), the mobile X-ray imaging apparatus will not fall over. However, when the rotation angle θ of the support column 6 is set in the direction in which the axis of the arm 5 coincides with the short axis direction 1b (width direction) of the X-ray imaging apparatus main body 1, if the arm 5 is extended to the maximum arm length Lb, the mobile X-ray imaging apparatus may fall over. Therefore, when the rotation angle θ of the support column 6 where the axis of the arm 5 coincides with the short axis direction (width direction) 1b of the X-ray imaging apparatus main body 1 is θ = 90 degrees and θ = -90 degrees, the maximum allowable arm length Lmax(θ) allowed for the arm 5 so as not to tip over the mobile X-ray imaging apparatus becomes a predetermined arm length La (Lb < La) smaller than the maximum arm length Lb. In the case of the structure of the arm 5 of the present embodiment, the arm length La is equal to the arm length of the arm 5 in a state where the manual first arm 5-1a and the manual second arm 5-1b are fully extended and the electric arm 5-2 is not extended. Also, within a range of a rotation angle θ of 40 degrees centered on the rotation angles θ = 90 degrees and -90 degrees of the support column 6 (that is, 70° < θ < 110°, -70° < θ < -110°), the maximum allowable arm length Lmax(θ) is a value that is equal to or greater than the arm length La and less than the maximum arm length Lb, and at θ = 90 degrees and -90 degrees, the maximum allowable arm length Lmax(θ) = La.

[0037] The maximum allowable arm length Lmax(θ) is obtained in advance by measurement or calculation. The obtained maximum allowable arm length Lmax(θ) is stored in the Lmax storage unit 36 in the form of a table, for example, as shown in FIG. 9(d). Note that it may be stored in the Lmax storage unit 36 in other forms such as mathematical formulas or graphs, not limited to tables.

[0038] Hereinafter, the operation of the control unit 9 will be described using the flowchart of FIG. 9(a). FIGS. 9(b) and 9(c) are examples of two types of determination tables used in the flowchart of FIG. 9(a). FIG. 9(d) is a table of the maximum allowable arm length Lmax(θ) for each rotation angle θ.

[0039] (Step 101) The determination unit 22 of the control unit 9 captures whether the extension button 18, the retraction button 19, and the brake release button 17-1 are in the ON state or the OFF state in order to determine what operation the operator is trying to perform.

[0040] (Step 102) The meaning determination unit 22 determines which pattern in the table of FIG. 9(b) the combination of the ON / OFF states of the extension button 18, the extension / contraction button 19, and the brake release button 17-1 captured in step 101 is.

[0041] When the brake release button 17-1 is ON and the extension button 18 and the extension / contraction button 19 are OFF, it is determined as "Pattern 1" in which an attempt is being made to manually extend or contract the manual arm 5-1 or rotate the support column 6.

[0042] When the brake release button 17-1 is OFF, the extension button 18 is ON, and the extension / contraction button 19 is OFF, it is determined as "Pattern 2" in which an attempt is being made to extend only the electric arm 5-2.

[0043] When the brake release button 17-1 is OFF, the extension button 18 is OFF, and the extension / contraction button 19 is ON, it is determined as "Pattern 3" in which an attempt is being made to contract only the electric arm 5-2.

[0044] When the brake release button 17-1 is ON, the extension button 18 is ON, and the extension / contraction button 19 is OFF, it is determined as "Pattern 4" in which an attempt is being made to extend the electric arm 5-2 while manually extending or contracting the manual arm 5-1 or rotating the support column 6.

[0045] When the brake release button 17-1 is ON, the extension button 18 is OFF, and the extension / contraction button 19 is ON, it is determined as "Pattern 5" in which an attempt is being made to contract the electric arm 5-2 while manually extending or contracting the manual arm 5-1 or rotating the support column 6.

[0046] When the brake release button 17-1 is OFF, the extension button 18 is ON, and the extension / contraction button 19 is ON, it is determined as "Pattern 6" in which it is not clear what the operator is trying to do.

[0047] Similarly, when the brake release button 17-1 is ON, the extension button 18 is ON, and the extension and retraction button 19 is ON, it is determined as "Pattern 7" where it is not clear what the operator is trying to do.

[0048] When the determination result is Patterns 1 to 5, the intention determination unit 22 proceeds to step 103. When the determination result is Patterns 6 or 7, it returns to step 101 without doing anything.

[0049] (Step 103) The stability determination unit 15 captures the rotation angle θ from the rotation angle detector 14 of the support column 6 and the current arm length Lr from the arm length detector 10.

[0050] (Step 104) The stability determination unit 15 captures the maximum allowable arm length Lmax(θ) corresponding to the rotation angle θ captured from the rotation angle detector 14 of the support column 6 from the Lmax storage unit 36 (see Fig. 9(d)) and compares it with the current arm length Lr captured from the arm length detector 10. When the current arm length Lr is smaller than the maximum allowable arm length Lmax(θ) (Lr < Lmax), the mobile X-ray imaging apparatus determines that there is no risk of tipping over and is stable, and proceeds to step 106.

[0051] On the other hand, when the current arm length Lr is equal to or greater than the maximum allowable arm length Lmax(θ) (L ≧ Lmax), the stability determination unit 15 proceeds to step 105.

[0052] (Step 105) The control unit 9 instructs the motor control unit 16 to retract the electric arm 5-2. The motor control unit 16 reverses the motor 11, pulls the electric arm 5-2 into the manual arm 5-1, and sets the arm 5 to an arm length with no risk of tipping over, then returns to step 101.

[0053] (Steps 106, 107) In step 104, when it is determined that the current arm length Lr is smaller than the allowable maximum arm length Lmax(θ) and there is no risk of tipping over, in step 106, the control unit 9 determines whether the extension button 18 captured in step 101 is in the ON state. If the extension button 18 is ON, the control unit 9 proceeds to step 107, instructs the motor control unit 16 to rotate the motor 11 forward, and extends the electric arm 5-2.

[0054] In step 106, if the extension button is not ON, the process proceeds to step 108.

[0055] (Steps 108, 109) In step 108, the control unit 9 determines whether the retraction button captured in step 101 is in the ON state. If it is ON, the process proceeds to step 109, where the control unit 9 instructs the motor control unit 16 to reverse the motor 11 and retract the electric arm 5-2.

[0056] In step 108, if the retraction button is not ON, the process proceeds to step 110.

[0057] (Steps 110, 111) In step 110, the control unit 9 determines whether the brake release button 17-1 captured in step 101 is in the ON state. If it is ON, the process proceeds to step 111, where the control unit 9 instructs the brake release unit 20 to turn off the column rotation brake 21-1 and the arm brake 21-2. As a result, the operator can manually rotate and extend or retract the manual arm 5-1.

[0058] In step 110, if the brake release button 17-1 is not in the ON state, the process returns to step 101.

[0059] As described above, when the rotation angle (θ) of the support column 6 is set so that the axis of the arm 5 coincides with the long axis direction 1a of the mobile X-ray imaging apparatus main body 1 in the mobile X-ray imaging apparatus according to the first embodiment, compared with the case where the rotation angle (θ) of the support column 6 is set so that the axis of the arm 5 coincides with the short axis direction 1b of the mobile X-ray imaging apparatus main body 1, by reducing the allowable maximum arm length Lmax(θ) allowed for the arm 5, attention is paid to the fact that the mobile X-ray imaging apparatus can be prevented from tipping over, and the control of the arm length is performed. Specifically, when the rotation angle (θ) of the support column 6 is set so that the axis of the arm 5 coincides with the short axis direction 1b of the mobile X-ray imaging apparatus main body 1, the control unit 9 controls the electric arm 5-1 to extend and contract it. Thereby, the current arm length Lr can always be controlled so as not to exceed the allowable maximum arm length Lmax(θ) at which the mobile X-ray imaging apparatus does not tip over.

[0060] <<Second Embodiment>> The mobile X-ray imaging apparatus according to the second embodiment will be described with reference to FIGS. 10 to 12.

[0061] In the mobile X-ray imaging apparatus according to the first embodiment, as shown in FIG. 8, within the range of the rotation angle θ = -90 degrees to 90 degrees of the support column 6 where the arm 5 is located above the mobile X-ray imaging apparatus main body 1, the allowable maximum arm length Lmax(θ) is set to the maximum arm length Lb of the arm 5. Therefore, the operator can extend the arm length Lr longer than the above-described predetermined arm length La in a state where the arm 5 is located above the mobile X-ray imaging apparatus main body 1. However, since the subject cannot be imaged in that state, when the operator rotates the support column 6 and tries to pivot the arm 5 forward, near the rotation angle θ = 90 degrees or -90 degrees, the current arm length Lr exceeds the allowable maximum arm length Lmax(θ) (= La) at the rotation angle θ = 90 degrees or -90 degrees. Therefore, near the rotation angle θ = 90 degrees or -90 degrees, in step 105 of the flow in FIG. 9(a), the control unit 9 needs to extend and contract the electric arm 5-2 to reduce the arm length Lr to La. And when the angle θ exceeds 90 or -90 degrees, the arm length Lr can be extended longer than the arm length La again.

[0062] In Embodiment 2, when attempting to turn the arm 5 forward in this manner, in order to avoid an operation in which the arm length Lr is once shortened near the rotation angle θ = 90 degrees or -90 degrees and then extended again after exceeding θ = 90 degrees or -90 degrees, as shown in FIG. 11, the control unit 9 is configured to be connected to the operation unit 25. As shown in FIG. 12, the operation unit 25 restricts the allowable maximum arm length Lmax(θ) within the range of the rotation angle θ = -90 degrees to 90 degrees among the values of the allowable maximum arm length Lmax(θ) for each rotation angle θ to a predetermined arm length La as shown in FIG. 12 by the operation of the operator.

[0063] As a result, when the arm 5 crosses the minor axis direction 1b by turning, the control unit 9 no longer once extends and contracts the arm 5-2, and unnecessary extension and contraction of the arm 5 can be avoided.

[0064] <<Embodiment 3>> The mobile X-ray imaging apparatus according to Embodiment 3 will be described with reference to FIGS. 13 to 19. FIG. 13 is a top view of the extended arm, FIG. 14 is a view of the arm in the direction of arrow B, FIG. 15 is a block diagram of the main configuration of the mobile X-ray imaging apparatus, and FIG. 16 is an explanatory diagram showing the allowable maximum arm length Lmax(θ) for each rotation angle θ of the arm 5 in Embodiment 3.

[0065] The mobile X-ray imaging apparatus according to Embodiment 3 is provided with a manual third arm 5-1c instead of the electric arm 5-2 as shown in FIG. 14, and the arm 5 is manually extended and retracted in three stages by the manual first, second, and third arms 5-1a, 5-1b, and 5-1c. Therefore, the mobile X-ray imaging apparatus according to Embodiment 3 does not include the motor 11 in FIG. 7 of Embodiment 1 in the arm 5.

[0066] The mobile X-ray imaging apparatus according to Embodiment 3 uses only a manual arm 5 and, similar to Embodiment 1, uses a brake and a buzzer to limit the extension of the arm 5 to be not more than the allowable maximum arm length Lmax(θ) set for each rotation angle θ of the column 6. The allowable maximum arm length Lmax(θ) of the arm 5 for each range of the rotation angle θ of the column 6 is the same as that in Embodiment 1 (see FIG. 16).

[0067] Also, the handles 17a and 17b are not provided with the extension button 18 and the contraction button 19 of the first embodiment, respectively. Inside both handles 17a and 17b, a brake release button 17-1 is disposed respectively. When the brake release button 17-1 is pressed, the control unit 9 releases both the column rotation brake 21-1 and the arm brake 21-2. This configuration is the same as that of the first embodiment. Also, in the third embodiment, a buzzer 38 is connected to the control unit 9. Inside the control unit 9, a brake release determination unit 115 is disposed instead of the stability determination unit 15.

[0068] The operation of the control unit 9 will be described using the flow of FIG. 16.

[0069] Thus, although the mobile X-ray imaging apparatus of the third embodiment has a configuration including only the manual arm 5, by controlling the column rotation brake 21-1, the arm brake 21-2, and the sounding of the buzzer 38, it is possible to control so that the arm 5 is not extended beyond the maximum allowable arm length Lmax(θ) set for each rotation angle θ of the column 6, similar to the first embodiment. Therefore, there is no risk of the X-ray imaging apparatus main body 1 tipping over, and the operator can extend the arm 5 stably.

Explanation of Reference Numerals

[0070] 1 X-ray imaging apparatus main body 1a Longitudinal axis direction 1b Short axis direction 2 X-ray generator 4 Front wheel 5 Arm 5-1 Manual arm 5-1a Manual first arm 5-1b Manual second arm 5-1c Manual third arm 5-2 Electric arm 5-3 Slide rail 6 Column 6a Flange 7 Catch column 8 Rear wheel 9 Control Unit 10 Arm Length Detector 11 Motor 12 Ball Screw 13 Gear 14 Rotation Angle Detector 15 Stability Judgment Unit 16 Motor Control Unit 17 Handle 17-1 Brake Release Button 17a Handle 17b Handle 18 Extension Button 19 Retraction Button 20 Brake Release Unit 21-1 Column Rotation Brake 21-2 Arm Brake 22 Intention Judgment Unit 25 Operation Unit 36 Storage Unit 37 Handle 38 Buzzer 81 Cart 115 Brake Release Judgment Unit

Claims

1. A mobile X-ray imaging apparatus comprising a carriage, an X-ray imaging apparatus main body mounted on the carriage, a support column, a telescopic arm having one end supported on a side surface of the support column and capable of extending and contracting, an X-ray generator, and a control unit, wherein the support column has a lower end mounted on the carriage and is supported by the carriage so as to be rotatable about a central axis of the support column, the X-ray generator is supported at a tip of the arm, the X-ray imaging apparatus main body has a long axis along a traveling direction and a short axis in a width direction, the control unit includes a storage unit in which a maximum allowable arm length Lmax(θ) allowed for the arm for the stability of the carriage, which is predetermined for each rotation angle θ of the support column, is stored in advance, the maximum allowable arm length Lmax(θ) is shorter when the rotation angle θ is such that the axis of the arm coincides with the short axis direction than when the rotation angle θ coincides with the long axis, the support column is provided with a rotation angle detector for detecting the rotation angle θ and a support column rotation brake for stopping the rotation of the support column, the arm is provided with an arm length detector for detecting a current arm length Lr, the control unit takes in the rotation angle θ detected by the rotation angle detector and the current arm length Lr output by the arm length detector, determines whether the arm length Lr is less than the maximum allowable arm length Lmax(θ) stored in the storage unit, and if the arm length Lr is not less than the maximum allowable arm length Lmax(θ), the arm is contracted or the support column rotation brake is turned on to prevent the support column from rotating. A mobile X-ray imaging apparatus characterized by this.

2. The mobile X-ray imaging apparatus according to claim 1, wherein the arm includes a cylindrical first arm having one end supported on a side surface of the support column, a cylindrical second arm disposed inside the first arm and capable of extending and contracting axially with respect to the first arm, and a third arm disposed inside the second arm and capable of extending and contracting axially from the second arm. A mobile X-ray imaging apparatus characterized by this.

3. The mobile X-ray imaging apparatus according to claim 2, wherein the arm includes a motor and a mechanism for extending and contracting the third arm with respect to the second arm by a rotational operation of the motor, the control unit operates the motor to contract the arm when the arm length Lr is not less than the maximum allowable arm length Lmax(θ). A mobile X-ray imaging apparatus characterized by this.

4. The mobile X-ray imaging apparatus according to claim 2, wherein when the second arm is fully extended from the first arm and the third arm is not extended, the length of the arm is designed to match the maximum allowable arm length Lmax(θ) at the rotation angle θ where the axis of the arm coincides with the minor axis direction. A mobile X-ray imaging apparatus characterized by this.

5. The mobile X-ray imaging apparatus according to claim 2, further comprising: a handle for manually extending and retracting the second arm with respect to the first arm; an arm brake for stopping the operation of manually extending and retracting the second arm with respect to the first arm; a brake release switch for turning off the column rotation brake and the arm brake; an extension button for instructing the operator to extend the third arm; and a retraction button for instructing the operator to retract the third arm. A mobile X-ray imaging apparatus characterized by this.

6. The mobile X-ray imaging apparatus according to claim 5, wherein the control unit determines whether the arm length L is less than the maximum allowable arm length Lmax(θ) stored in the storage unit only when the combination of the on / off states of the extension button, the retraction button, and the brake release switch is any of a plurality of predetermined combinations. A mobile X-ray imaging apparatus characterized by this.

7. The mobile X-ray imaging apparatus according to claim 1, further comprising: an arm brake for stopping the telescopic movement of the arm; a brake release switch for turning off the column rotation brake and the arm brake; and a buzzer, wherein the arm is an arm that can be telescoped only manually, and the control unit applies both the column rotation brake and the arm brake when the arm length Lr is not less than the maximum allowable arm length Lmax(θ), and when the brake release switch is pressed in that state, releases only the arm brake. A mobile X-ray imaging apparatus characterized by this.

8. The mobile X-ray imaging apparatus according to claim 7, wherein after releasing only the arm brake, the control unit captures the arm length Lr and determines whether the operator is extending the arm. If the operator is extending the arm, the buzzer is sounded and the arm brake is applied again. A mobile X-ray imaging apparatus characterized by this.

9. The mobile X-ray imaging apparatus according to claim 8, wherein after only releasing the arm brake, the control unit determines that the operator is extending the arm, and when the operator is retracting the arm, the control unit further determines whether the arm length Lr is shorter than a predetermined arm length La, and when the arm length Lr is shorter than the predetermined arm length La, the control unit releases the column rotation brake. The mobile X-ray imaging apparatus is characterized by this.

10. A control method for a mobile X-ray imaging apparatus, comprising: a cart; an X-ray imaging apparatus main body mounted on the cart; a column rotatable about a central axis; a telescopic arm having one end supported on a side surface of the column and capable of extending and retracting; an X-ray generator supported at a tip of the arm; and a control unit, wherein the X-ray imaging apparatus main body has a major axis along the traveling direction and a minor axis in the width direction, the control unit captures the rotation angle θ of the column and the current arm length Lr, and determines whether the arm length Lr is less than a maximum allowable arm length Lmax(θ) allowed for the arm for the stability of the cart, which is predetermined for each rotation angle θ of the column. When the arm length Lr is not less than the maximum allowable arm length Lmax(θ), the control method for the mobile X-ray imaging apparatus is characterized in that the arm is retracted or the column is not rotated.

Images