Deciding on shifting treatment table frame

Abstract

In one embodiment, a method 200 is described. The method includes receiving 202 an indication of a weight on a movable support 106 of a couch assembly 100. The movable support is movable relative to a couch frame 110 of the couch assembly. The method further includes determining 204 a horizontal shift of the couch frame relative to an imaging device 102 associated with the couch assembly based on a shift model indicative of the horizontal shift as a function of the indicated weight on the movable support and a horizontal position of the movable support relative to the couch frame.

Description

[Technical field]

[0001] The present invention relates to a method, a tangible machine-readable medium and an apparatus for determining a shift of a couch frame relative to an imaging device. [Background technology]

[0002] During a patient imaging operation, the movable support of the treatment table assembly can move the patient to a specified position so that an imaging device, such as a computed tomography (CT) scanner, can acquire imaging data in an imaging plane corresponding to a specified portion of the patient's body. Summary of the Invention [Problem to be solved by the invention]

[0003] However, the accuracy of the patient positioning relative to the imaging plane may affect the outcome of the imaging operation. For example, if there is an error in the position of the patient relative to the imaging plane, the imaging data may not correspond to the designated part of the patient. In some cases, it may be necessary to move the patient again so that the designated part of the patient is imaged, which may unnecessarily increase the patient's exposure to radiation and / or increase the time spent performing the imaging operation. In some cases, errors may not be recognized, which may lead to an inaccurate analysis of the imaging data. Errors in the position of the patient relative to the imaging plane in the vertical direction are described in DE 102007060690 A1 and US 2016 / 0113598 A1. [Means for solving the problem]

[0004] Aspects or embodiments described herein relate to improving the accuracy of positioning of a subject, such as a patient, relative to an imaging device. The aspects or embodiments described herein may avoid one or more problems associated with or resulting from inaccurate positioning of a subject during an imaging operation.

[0005] In a first aspect, a method is described. The method is a computer-implemented method. The method includes receiving an indication of a weight on a movable support of a treatment couch assembly. The movable support is movable relative to a treatment couch frame of the treatment couch assembly. The method further includes determining a horizontal shift of the treatment couch frame relative to an imaging device associated with the treatment couch assembly based on a shift model indicative of the horizontal shift as a function of the indicated weight on the movable support and a horizontal position of the movable support relative to the treatment couch frame.

[0006] Several embodiments relating to the first aspect and other aspects are described below.

[0007] In some embodiments, the method includes receiving an indication of an expected position for moving the movable support to the expected position relative to the couch frame to provide the movable support at a specified position relative to the imaging device, the method further including determining a horizontal shift of the expected position.

[0008] In some embodiments, the method includes moving the movable support to a corrected position (hereinafter referred to as the "corrected position") determined based on a difference between the expected position and the horizontal shift, such that the movable support is provided at the specified position.

[0009] In some embodiments, moving the movable support to the correct position comprises causing a movable support actuator of the couch assembly to move the movable support to the correct position.

[0010] In some embodiments, moving the movable support to the modified position includes generating a command configured for a movable support actuator to move the movable support to the modified position, and transmitting the command to the movable support actuator to actuate the movable support actuator in accordance with the command.

[0011] In some embodiments, the movable support actuator is configured to move the movable support horizontally relative to a surface supporting the couch assembly such that the movable support is provided at a designated position.

[0012] In some embodiments, the indication of weight includes an indication of a current supplied to a couch frame actuator of the couch assembly. The couch frame actuator can be configured to control the height of the moveable support relative to a surface supporting the couch assembly.

[0013] In some embodiments, the couch frame actuator is configured to maintain the moveable support at a particular height during horizontal movement of the moveable support relative to the couch frame.

[0014] In some embodiments, the method includes receiving an indication of weight by receiving an indication of current. The method can further include estimating the weight by using a vertical force balance model of the current required to provide the movable support at a specified height. The method can further include receiving a command specifying an expected position to which the movable support is moved relative to the couch frame. The method can further include determining a predicted shift of the couch frame according to a shift model based on the estimated weight and the predicted position. The method can further include generating a revised or "modified" command to specify a corrected position to which the movable support is moved relative to the couch frame based on a difference between the expected position and the predicted shift relative to the expected position.

[0015] In some embodiments, the shift model is determined from a set of measurements for the horizontal shift and a corresponding set of indication values ​​for the horizontal position of the movable support at which the horizontal shift is measured.

[0016] In some embodiments, the shift model is based on a linear function that is fitted to a set of measurements for the horizontal shift and a corresponding set of indication values ​​for the horizontal position of the movable support.

[0017] In some embodiments, the shift model is determined from a set of sign values ​​for the horizontal position of the movable support for each sign value of the set of sign values ​​for the weight on the movable support.

[0018] In a second aspect, a tangible machine-readable medium is described having instructions that, when executed by at least one processor, cause the at least one processor to perform a method of the first aspect or any related embodiment.

[0019] In a third aspect, an apparatus is described. The apparatus has at least one processor communicatively coupled to an interface configured to receive an indication of a weight on a movable support of a treatment couch assembly. The movable support is movable relative to a treatment couch frame of the treatment couch assembly. The apparatus further has a tangible machine-readable medium storing instructions readable and executable by the at least one processor to execute a method. The method includes receiving an indication of the weight. The method further includes determining a horizontal shift of the treatment couch frame relative to an imaging device associated with the treatment couch assembly based on a shift model indicative of the horizontal shift as a function of the indicated weight on the movable support and the horizontal position of the movable support relative to the treatment couch frame.

[0020] Embodiments relating to the third aspect and other aspects are described below.

[0021] In some embodiments, the interface is further configured to receive an indication of an expected position at which the movable support is moved relative to the couch frame to provide the movable support at a specified position relative to the imaging device. The interface can be further configured to send a command to a movable support actuator of the couch assembly. The command can be configured to actuate the movable support actuator. The instructions can further comprise instructions readable and executable by at least one processor to perform the method. The method includes receiving an indication of the expected position. The method can further include determining a horizontal shift relative to the expected position. The method can further include moving the movable support to a corrective position determined based on a difference between the expected position and the horizontal shift such that the movable support is provided at a specified position, the movement to the corrective position being performed by generating a command to the movable support actuator to move the movable support to the corrective position and sending the command via the interface to the movable support actuator to cause actuation of the movable support actuator according to the command.

[0022] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which: [Brief description of the drawings]

[0024] [Figure 1] Schematic diagram of a scenario depicting an error in the positioning of a movable support of a treatment table assembly as referred to in various embodiments. [Diagram 2] FIG. 13 illustrates a method for determining a couch frameshift according to one embodiment. [Diagram 3] FIG. 13 illustrates a method for determining and correcting couch frameshift, according to various embodiments. [Figure 4]Schematic diagram depicting a model of the treatment table assembly for weight estimation. [Diagram 5] FIG. 13 illustrates a method for determining and correcting couch frameshift, according to one embodiment. [Figure 6] 13 is a graph showing a set of measurements of couch frame shift as a function of the position of the movable support. [Figure 7] 7 is a graph illustrating a method for calculating coefficients of a shift model according to one embodiment based on a curve fitted to the data of FIG. 6; [Figure 8] 1 is a schematic diagram of a machine-readable medium for determining couch frameshift according to one embodiment. [Figure 9] 1 is a schematic diagram of an apparatus for determining and / or correcting couch frameshift according to various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] 1 is a schematic diagram of an exemplary couch assembly 100 associated with an imaging device 102, such as a computed tomography (CT) scanner. The couch assembly 100 is used to support a subject 104, such as a patient. Two configurations (a) and (b) of the couch assembly 100 are shown. For ease of explanation, specific reference numbers or connecting elements are not shown in both configurations.

[0026] As shown by configuration (a), the subject 104 is positioned on a movable support 106 of the couch assembly 100. The movable support 106 may be referred to as a "table," "tabletop," or "couch." As shown by configuration (b), movement of the movable support 106 from the position shown in configuration (a) positions the subject 104 in an imaging plane 108 associated with the imaging device 102. Thus, by moving the movable support 106 relative to the imaging plane 108, different portions of the subject 104 can be imaged. For example, multiple imaging "slices" can be acquired at different axial positions along the subject 104 by moving the subject 104 relative to the imaging plane 108 and acquiring an image at each of the axial positions.

[0027] The couch assembly 100 also includes a couch frame 110 for supporting the movable support 106 and facilitating movement (e.g., horizontal movement) of the movable support 106 relative to the imaging device 102. The couch frame 110 is configured to balance the weight W of the subject 104 (and any other equipment supported by the movable support 106) so that the subject 104 can be positioned at a particular distance (e.g., height) above a surface 112, such as a floor, on which the couch assembly 100 is placed.

[0028] In this exemplary couch assembly 100, the couch frame 110 has a scissor mechanism 114 for supporting a base member 116 to which the movable support 106 is attached. Other mechanisms are possible, as described below. In this example, the scissor mechanism 114 has two ("lever") members 118 that are configured to lever relative to one another via a pivot 120 at the center of each member 118.

[0029] One end of each member 118 is pivotally connected to the base member 116, while the other end of each member 118 is pivotally attached to the surface 112. The ends of the two members 118 pivotally connected to the base member 116 are movably spaced apart from each other so that the base member 116 is properly supported by the scissor mechanism 114 (e.g., so that the base member 116 is parallel to the surface 112). Similarly, the other ends of the two members 118 pivotally attached to the surface 112 are movably spaced apart from each other. The couch assembly 100 has a couch frame actuator 122 (e.g., an electric motor) configured to control / adjust the height of the subject 104 by levering the members 118 relative to each other (and by causing relative movement between the ends of the members 118 connected to the base member 116). In this embodiment, the couch frame actuator 122 is attached to the surface 112 and configured to apply a force to one end of the members 118 attached to the surface 112. The end of the other member 118 attached to the surface 112 is fixed in place as shown by a fixed mount 124 .

[0030] Thus, in use, the couch frame actuator 122 can apply a force to the member 118 to move the ends of the member 118 attached to the surface 112 closer together. This movement of the member 118, by lever movement about the pivot 120, raises the base member 116 and thus the subject 104. The weight W can be balanced using a specific force applied by the couch frame actuator 122. By varying this force, the subject 104 can be raised or lowered relative to the surface 112. If the couch frame actuator 122 has an electric motor, the current supplied to the electric motor can be varied to controllably adjust the height of the subject 104.

[0031] As highlighted above, the configuration of the scissor mechanism 114 and associated portions of the couch assembly 100 may be different than that shown and described in connection with FIG. 1. For example, the two members 118 may not be configured in a scissor-like configuration as shown by FIG. 1, but may instead move independently of one another (e.g., the members 118 may not be connected to one another via the pivot 120). Furthermore, the number of members 118 may be different (e.g., three or more members 118 may be used, or one member may be used). Furthermore, the configuration of the couch frame actuator 122 may be different (e.g., the couch frame actuator 122 may be connected to a different portion of the member 118, etc.).

[0032] Thus, functionally, the couch assembly 100 is configured to facilitate adjustment / control of the height of the subject 104 while balancing the weight W, such that the subject 104 can be provided at a specified height. Any configuration of the couch assembly 100 that facilitates such functionality may be relevant to the present disclosure.

[0033] It should be understood that the configuration shown in FIG. 1 is schematic to better illustrate the possible components of the treatment table assembly 100, and thus the configuration and design of the components may differ from that shown in FIG.

[0034] As described below, the configuration of the couch assembly 100 may introduce errors in the positioning of the subject 104 relative to the imaging device 102 .

[0035] The couch assembly 100 has a movable support actuator 126 for moving the movable support 106 relative to the couch frame 110. In this example, the movable support actuator 126 is mounted between the base member 116 and the movable support 106. In use, the movable support actuator 126 (electric motor, hydraulic system, etc.) applies a force between the base member 116 and the movable support 106, causing relative motion therebetween. The movable support 106 is attached to a sliding mechanism 128 (e.g., at least one roller) mounted to the base member 116 to facilitate movement (e.g., sliding movement) between the movable support 106 and the base member 116.

[0036] To move between configurations (a) and (b), a command ("L1_cmd") is sent by a controller 130 communicatively coupled to the movable support actuator 126, so that the movable support 106 moves a distance "L1" so that the end of the movable support 106 above the treatment table frame 110 is at a specified position 132 (which means that the subject 104 is provided at the specified position defined by the command L1_cmd). There may be an error "err1" in the actual moving distance. Thus, a correction mechanism, such as a servo motor (not shown), can correct this error err1.

[0037] The controller 130 (or a different controller) can also be communicatively coupled to the couch frame actuator 122. Thus, during use, the controller 130 can send commands to the couch frame actuator 122 to control / adjust the vertical position (e.g., height) of the subject 104 and / or the movable support actuator 126 to control / adjust the position (e.g., horizontal position) of the subject 104 relative to the imaging device 102. The controller 130 can receive feedback from the couch frame actuator 122 and / or the movable support actuator 126, such as an indication of the current supplied and / or an indication of the configuration of the couch frame actuator 122 and / or the movable support actuator 126.

[0038] Between the two configurations (a) and (b), when the subject 104 is moved towards and into the imaging plane 108 by the movable support 106, the position of the center of gravity is shifted, so that the end of the movable support 106 that overhangs the treatment table frame 110 is provided at a designated position 132.

[0039] In configuration (a), a force F1 acts on the couch frame 110 at the point shown in FIG. 1 (ie, the point where the end of member 118 is connected to base member 116).

[0040] In configuration (b), the center of gravity has shifted beyond the center of the treatment table frame 110 to a position where it no longer acts, as shown by configuration (a), so a larger force F2 acts on the treatment table frame 110 at the same point.

[0041] This larger force F2 results in an additional compression of the couch frame 110 with a corresponding horizontal shift of the couch frame 110. This results in a movement of the couch frame 110 relative to the surface 112 toward the imaging device 102. In some cases, this compression may also result in a (relatively small) decrease in the height of the couch frame 110. As shown in configuration (b), the position of the couch frame 110 is shifted by a distance L2 from the previous position of the couch frame 110. In particular, the end of the base member 116 in configuration (a) is indicated by a line 134 in configuration (b). The distance between the end of the base member 116 and the line 134 corresponds to the shift L2. Thus, the larger the distance L1, the larger the distance L2, the larger the force acting on the couch frame 110 due to the shift in the center of gravity, and the larger the lever effect acting on the scissor mechanism 114.

[0042] However, the correction mechanism for correcting the error err1 associated with L1 may not be able to correct the shift L2.

[0043] While in configuration (a), the movement control reference frame of the movable support 106 is based on the treatment couch frame 110 (i.e., the movement of the movable support 106 is defined relative to the reference frame defined by the treatment couch frame 110). However, the reference frame of the treatment couch frame 110 itself is defined relative to the surface 112 (e.g., the "ground" reference frame). Similarly, the imaging device 102 is fixed relative to the surface 112. Thus, assuming that the treatment couch frame 110 and the imaging device 102 are fixed relative to each other, the movement of the movable support 106 is relative to the surface 112 itself. For example, as shown by configuration (a), when the treatment couch frame 110 is not shifted, the reference frames of the movable support 106 and the treatment couch frame 110 are the same.

[0044] However, when the couch frame 110 is shifted as shown by configuration (b), deviations / offsets are introduced, which means that assumptions about the reference frame cannot be relied upon to ensure accurate positioning of the subject 104 relative to the imaging device 102. The deviations / offsets may affect the quality and / or results of the imaging operation. In some cases, the deviations may be such that additional images need to be acquired, which may unnecessarily increase the patient's exposure to radiation and / or increase the time spent performing the imaging operation. In some cases, the errors may not be recognized, which may lead to inaccurate analysis of the imaging data.

[0045] Currently, deviation / offset of the couch frame 110 is not taken into account, and therefore a systematic error proportional to the moving distance L1 may be introduced. The embodiments described herein can facilitate the correction of this deviation / offset. For example, certain embodiments described herein can determine a couch frame shift. Certain embodiments can take action to correct the determined couch frame shift.

[0046] FIG. 2 illustrates a method 200 (e.g., a computer-implemented method) of determining a couch frame shift according to one embodiment. In describing the method 200, reference is made to FIG. 1. FIG. 1 illustrates a controller 130 capable of implementing the method 200. The controller 130 can be implemented by a computer, such as a user computer communicatively coupled to a user interface, or a server or cloud-based service (e.g., communicatively coupled to a user computer and / or a user interface). Thus, the method 200 can be implemented locally (e.g., on a user computer at the location of the couch assembly 100) or elsewhere (e.g., on a server or in the cloud). Commands and / or feedback can be communicated between the controller 130 and the couch frame actuator 122 and / or the movable support actuator 126 to facilitate the implementation of certain methods (e.g., method 200) described herein.

[0047] The method 200 includes, in block 202, receiving an indication of a weight on a movable support 106 of the couch assembly 100. The movable support 106 is movable relative to a couch frame 110 of the couch assembly 100. Further discussion regarding the indication of weight is provided below.

[0048] The method 200 further includes, in block 204, determining a shift L2 of the couch frame 110 relative to the imaging device 102 associated with the couch assembly 100. The determination of the shift L2 is based on a shift model (the description of which is given below) that indicates the shift as a function of the weight indicated on the movable support 106 and the position of the movable support 106 relative to the couch frame 110. The position of the movable support 106 can be defined with respect to the moved distance L1. For example, the end of the movable support 106 is at the designated position 132 according to the moved distance L1.

[0049] The method 200 can allow a couch frame shift to be determined. Thus, as described in more detail below, a correction can be applied to the command L1_cmd to ensure that the subject 104 is provided at a specified position. For example, during an imaging operation, an operator can command the movable support 106 to move to a specified position (e.g., defined by a fixed point such as an end of the movable support 106 provided at a specified position 132). However, to correct for a couch frame shift that could potentially lead to the subject 104 being moved to an incorrect (e.g., unexpected) position, the command can be modified to take into account the (expected) couch frame shift so that the subject 104 is moved to a correct position (e.g., expected or specified position).

[0050] Such corrections can improve the quality and / or results of imaging operations. In some cases, the corrections can avoid the need to acquire additional images. In some cases, the corrections can improve the quality and / or results of analysis of the imaging data.

[0051] 3 illustrates a method 300 (e.g., a computer-implemented method) for determining and correcting couch frameshift, according to various embodiments. Method 300 can be implemented in the same manner (e.g., using controller 130) as method 200. For example, method 300 can have the same or similar functions as method 200. Refer to FIGS. 1 and 2 as needed. Some blocks of method 300 may not need to be implemented and / or some blocks of method 300 can be performed in a different order than illustrated by FIG. 3.

[0052] In some embodiments, the method 300 includes receiving (302) an indication of an expected position to which the movable support 106 is to be moved relative to the couch frame 110 in order to provide the movable support 106 to the designated position 132 relative to the imaging device 102. The "expected position" can refer to the position to which the movable support 106 is to be moved (i.e., after the command L1_cmd is executed). The "expected position" is based on the assumption that the reference frame of the couch frame 110 does not shift when moving the movable support 106 to the designated position 132. However, the command L1_cmd may not result in the movable support 106 being moved to the designated position 132. Rather, the command L1_cmd does not take into account the shift described above. Thus, the method 300 further includes, in block 304, determining a shift with respect to the expected position (e.g., according to the method 200).

[0053] In some embodiments, the method 300 includes, in block 306, moving the movable support 106 to a corrected position, determined based on the difference between the expected position and the shift, such that the movable support 106 is provided at the designated position 132 (i.e., as expected). Thus, the "corrected position" takes into account the shift L2. In other words, if the treatment couch frame is shifted by L2, the command L1_cmd can be modified to take this into account. For example, if the shift is a distance L2, the command can specify that the movable support 106 moves by a distance L1-L2. As a result of this modified command, the subject 104 can be positioned correctly or as expected (since the corrected position L1-L2 of the movable support 106 relative to the treatment couch frame 110 results in the movable support 106 being provided correctly at the designated position 132).

[0054] In some embodiments, moving the movable support 106 to the correct position includes causing the movable support actuator 126 of the couch assembly 100 to move the movable support 106 to the correct position in block 308 .

[0055] In some embodiments, the method 300 of moving the movable support to a corrected position according to block 308 includes generating a command to the movable support actuator 126 to move the movable support 106 to the corrected position (e.g., relative to a reference frame defined by the couch frame 110) at block 310. Block 308 further includes sending a command to the movable support actuator 126 to actuate the movable support actuator 126 according to the command at block 312.

[0056] In some embodiments, the movable support actuator 126 is configured to move the movable support 106 horizontally relative to the surface 112 supporting the treatment table assembly 100, such that the movable support 106 (e.g., the end of the movable support 106 that overhangs the treatment table frame 110) is provided to a designated position 132.

[0057] In some embodiments, the couch frame actuator 122 is configured to control the height of the moveable support 106 relative to the surface 112 .

[0058] In some embodiments, the indication of weight includes an indication of the current supplied to the couch frame actuator 122 .

[0059] In some embodiments, the couch frame actuator 122 is configured to maintain the movable support 106 at a particular height during horizontal movement of the movable support 106 relative to the couch frame 110 .

[0060] An embodiment illustrating the estimation of weight (used to provide an indication of weight) is described in more detail below.

[0061] Figure 4 shows a simplified diagram of a couch assembly 400 similar to the couch assembly 100 shown by Figure 1. Reference numbers for features of the couch assembly 400 that are the same as or similar to corresponding features of the couch assembly 100 are incremented by 300. Some features are not shown or described for ease of illustration, and reference is made to Figure 1, where appropriate.

[0062] The couch assembly 400 has a scissor mechanism, which can be modeled to determine a weight W. The weight W of the components of the couch assembly 400, such as the base member 416 and the movable support (not shown), is fixed. However, the weight may vary depending on the subject's weight and the weight of any other equipment (not shown) provided on the movable support 106.

[0063] The couch frame actuator 422 is used to balance the vertical forces exerted by components, the weight of the subject, etc. If the couch frame actuator 422 has an electric motor to exert a force to balance the vertical force, the current supplied to the electric motor can be changed accordingly. Based on the current feedback, the weight W can be estimated using the following vertical force balance model: θ=arcsin((H-h1-h2) / 2R) F=W * g * 2 * R / r * cosθ * (1-cosθ) F * p=T * i * 2 * π * ηT T=η e *KT*I W=ηe * KT * I ​​* i * 2 * π * (r*ηT) / (p*g*2*R*cosθ*(1-cosθ))

[0064] where θ is the interior angle between the member 118 and the surface 412, g is the gravity coefficient (constant), H is the height of the couch frame 110, h1 is the height of the base member 116 (sub-pallet), h2 is the height of the couch base 436 (not shown before, but the top of the couch base 436 represents the surface 112), F is the force applied to the member 118 by the couch frame actuator 122, p is the screw lead associated with the screw (connecting the member 118 to the couch frame actuator 122) driven by the couch frame actuator 122, T is the motor torque associated with the couch frame actuator 122, i is the transmission ratio, and η e is the motor efficiency, KT is the motor torque coefficient, I is the current supplied to the couch frame actuator 122, R is the half length of the member 118, and r is the radius of the pivot 120.

[0065] In the above equation, the height H and the motor current I are variables, and other parameters are constant. To simplify the weight estimation, the height H of the treatment table is assumed to be fixed during the weight estimation. Also, the relationship between the weight W and the current I is assumed to be linear. Therefore, a linear curve can be fitted to the actual measurement data of the current. In other words, the current I may depend linearly on the weight W.

[0066] Thus, the weight can be estimated such that an indication of this weight can be used to determine a shift according to certain methods described herein. Rather than having a separate sensor to measure the weight, certain embodiments can facilitate a simple method of estimating the weight.

[0067] FIG. 5 illustrates a method 500 (e.g., a computer-implemented method) for determining and correcting a couch frame shift, according to one embodiment. In this embodiment, the method 500 uses a weight estimate determined according to the model described in connection with FIG. 4, but in other embodiments, the weight estimate can be provided by a separate weight sensor. The method 500 can be implemented in the same manner (e.g., using the controller 130) as the methods 200, 300. For example, the method 500 can have the same or similar functions as the methods 200 and / or 300. Refer to previous figures, if necessary. Some blocks of the method 500 may not need to be implemented and / or some blocks of the method 500 can be performed in a different order than that illustrated by FIG. 5.

[0068] The method 500 includes, at block 502, receiving an indication of weight by receiving an indication of a current (eg, a current as referenced in FIG. 4).

[0069] The method 500 further includes, at block 504, estimating the weight by using a vertical force balance model (e.g., as described in connection with FIG. 4) of the current required to provide the movable support 106 at a particular height.

[0070] The method 500 further includes, at block 506, receiving a command (eg, “L1_cmd”) specifying an expected position to which the movable support 106 is to move relative to the couch frame 110.

[0071] The method 500 further includes, in block 508, determining a prescribed shift (e.g., "L2") of the treatment couch frame according to a shift model (see FIG. 1 and described in more detail below) based on the estimated weight and the expected position (e.g., defined by "L1").

[0072] The method 500 further includes, in block 510, generating a modified command specifying a modified position to which the movable support 106 should move relative to the treatment table frame 110 based on the difference between the expected position and the expected shift relative to the expected position (e.g., "L1-L2").

[0073] Next, a method for determining a "shift model" for determining the couch frame shift will be described.

[0074] The shift model is determined by obtaining measurements of the actual position of the couch frame 110 relative to the imaging device 102 (e.g., ground reference frame) for a set of (horizontal) positions of the movable support 106 (ranging from 0 to 1800 mm) for each of a set of different weights on the movable support 106 (75, 135, 185, 217, 274, 307 kg). The "actual position" can be measured using an independent measurement of the distance between a fixed point on the movable support 106 (e.g., an end of the movable support 106 resting on the couch frame 110 or another suitable point) and a fixed point defined with respect to the surface 112 (e.g., the imaging device 102 itself or another suitable point). Such an independent measurement can be performed by a laser-based position encoder, for example, using laser-based interferometry.

[0075] Thus, in this example, there are six data sets, i.e., one data set for each weight, and the shift (i.e., the difference between the actual position and the expected position of the movable support 106) is measured for a set of positions in the range 0 to 1800 mm.

[0076] 6 shows a graph of the shift (in mm) as a function of the (expected) position (in mm) of the movable support 106 (relative to the couch frame 110) for each of the six data sets, with the steepest curve corresponding to the heaviest weight of 307 kg and the gentlest curve corresponding to the lightest weight of 75 kg.

[0077] As can be seen, the shift curve is linear and can be fitted with a linear function such as Y=K(W)*P+D(W), where Y is the measured shift, K(W) is a proportionality coefficient (corresponding to the slope of the data set as a function of weight W), P is the expected position of the movable support 106, and D(W) is an offset (corresponding to where the fitted curve crosses the y-axis). The curve can be fitted with any suitable algorithm, such as a linear regression algorithm. For the data set shown, the curve is fitted with a 95% confidence limit.

[0078] To obtain linear functions of K(W) and D(W) with respect to weight W, for each weight, K(W) and D(W) are plotted as described below.

[0079] FIG. 7 shows a graph plotting K(W) and D(W) as a function of weight W, as well as a linear curve fitted to each variable. The confidence limits are 95%. The positive slope shown in FIG. 7 represents K(W) and the negative slope represents D(W). Thus, if weight W is estimated as above, the couch frame shift curve can be determined by obtaining K(W) and D(W) for the estimated weight (as a function of the expected position of the movable support 106). The values ​​K(W) and D(W) thus represent the "shift model" described above.

[0080] In other words, a "shift model" can be represented by ratio coefficients and offsets that are fitted to a set of measurement data, where the measurement data includes actual measurements of the position of the movable support 106 (relative to the imaging device 102 or the "ground" reference frame) for each of a set of expected positions of the movable support 106 (to determine the "actual" shift). The measurement data can be scaled by weight, such that the shift model is weight dependent, for example, as illustrated by the currents discussed above.

[0081] Several embodiments relating to the shift model are described below. In some embodiments, the shift model is determined from a set of measurements for the shift and a set of corresponding indicated values ​​for the position of the movable support 106 where the shift is measured. In some embodiments, the shift model is based on a linear function fitted to the set of measurements for the shift and a corresponding set of indicated values ​​for the position of the movable support 106. In some embodiments, the shift model is determined for each indicated value of the set of indicated values ​​for the weight on the movable support 106 from the set of indicated values ​​for the position of the movable support.

[0082] To correct the shift determined according to the shift model, the command (e.g., "L1_cmd") can be modified based on the (expected) position of the movable support 106. For example, if the command is configured to move the movable support 106 by a distance "D1", the shift "S1" can be estimated using the shift model according to S1=K(W)*D1 (e.g., when the offset is relatively small). Thus, the command can be modified as "D1-S1" or "(1-K(W))*D1". In use, the shift model can be used to modify commands generated in other ways and sent to the movable support actuator 126. In other words, the command received by the controller 130 to move the movable support 106 by the (expected) distance D1 can be modified by the difference between D1 and the (estimated) shift, i.e., D1-S1.

[0083] Thus, certain embodiments described herein can compensate for the movement error introduced by the shift without adding additional sensors to the setup. In some embodiments, a force balance model can be used to estimate the load or weight on the movable support 106. The shift model can be generated based on a set of measurements. The shift model can be used to estimate the couch frame shift for a given position of the movable support 106 at the estimated weight. Thus, certain embodiments can facilitate correction of the motion commands used to drive the movable support 106 to a specified position such that the subject 104 is more accurately positioned with respect to the imaging device 102 (compared to the case where the shift is not taken into account).

[0084] 8 illustrates a tangible, machine-readable medium 800 according to one embodiment. The tangible, machine-readable medium 800 has instructions 802 that, when executed on at least one processor 804, cause the at least one processor 804 to implement certain methods described herein (e.g., methods 200, 300, 500). Any of the methods described herein can be implemented by the tangible, machine-readable medium 800 causing the at least one processor 804 to implement such methods.

[0085] FIG. 9 shows an apparatus 900 for determining a couch frame shift according to various embodiments. The apparatus 900 has at least one processor 902 (e.g., realized by the controller 130 shown by FIG. 1). The at least one processor 902 is communicatively coupled to an interface 904 for communicating with the couch frame actuator 122 and / or the movable support actuator 126 (e.g., for receiving information such as current indications and / or for sending commands for controlling the respective actuators 122, 126). In this embodiment, the interface 904 is configured to receive an indication of a weight on the movable support 106. As mentioned above, the movable support 106 is movable relative to the couch frame 110 of the couch assembly 100. The interface 904 may be part of the controller 130 referred to in FIG. 1, and reference is made to certain features of the aforementioned figures in the description of the apparatus 900.

[0086] The apparatus 900 further includes a tangible, machine-readable medium 906 storing instructions 908 readable and executable by the at least one processor 902 to perform a method corresponding to some of the methods described herein (e.g., any of methods 200, 300, and / or 500).

[0087] In one embodiment, the instructions 908 are configured to cause at least one processor 902 to perform the method 200 .

[0088] In some embodiments related to the above embodiments, the interface 904 is further configured to receive an indication of an expected position at which the movable support 106 is moved relative to the couch frame 110 to provide the movable support 106 at the designated position 132 relative to the imaging device 102. The interface 904 can be further configured to send a command to the movable support actuator 126 of the couch assembly 100. Such a command can be configured to actuate the movable support actuator 126. In such an embodiment, the instructions 908 can be configured to cause the at least one processor 902 to execute the method 300. In the context of the device 900, the method 300 includes receiving an indication of the expected position, determining a shift relative to the expected position, and moving the movable support 106 to a corrected position determined based on a difference between the expected position and the shift, such that the movable support 106 is provided at the designated position 132. The generated "corrected" command to move the movable support 106 is configured to cause the movable support actuator 126 to move the movable support 106 to the corrected position. The modified command is sent to the movable support actuator 126 via the interface 904, causing the movable support actuator 126 to actuate in accordance with the command.

[0089] In some embodiments, any other method or combination of the methods according to the various embodiments described herein may be realized by storing instructions (e.g., instructions 802, 908) that, when executed by at least one processor 804, 902, realize the method.

[0090] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive, and the invention is not limited to the disclosed embodiments.

[0091] One or more features described in one embodiment may be combined with or substituted for features described in another embodiment.

[0092] Embodiments of the present disclosure may be provided as a method, a system, or a combination of machine-readable instructions and processing circuitry. Such machine-readable instructions may be contained on a non-transitory machine (e.g., computer) readable storage medium (including, but not limited to, disk storage devices, CD-ROMs, optical storage devices, etc.) having computer-readable program code therein or thereon.

[0093] The present disclosure will be described with reference to flowcharts and block diagrams of methods, apparatuses, and systems according to embodiments of the present disclosure. Although the above flowcharts show a specific instruction execution order, the instruction execution order may differ from that shown. Blocks described in connection with one flowchart may be combined with blocks of another flowchart. It should be understood that each block in the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, may be implemented by machine-readable instructions.

[0094] The machine-readable instructions can be executed, for example, by a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other field programmable gate array data processing apparatus to realize the functions described and illustrated in the figures. In particular, a processor or processing circuit, or a module thereof, can execute machine-readable instructions. Thus, the functional modules of the apparatus and other devices described herein can be realized by a processor that executes machine-readable instructions stored in a memory, or a processor that operates according to instructions embedded in a logic circuit. The term "processor" should be interpreted broadly to include a CPU, a processing unit, an ASIC, a logic unit, or a programmable gate array, etc. All the methods and functional modules can be executed by a single processor or can be divided among several processors.

[0095] Such machine-readable instructions may also be stored in a computer-readable storage device that is capable of directing a computer or other field programmable gate array data processing device to operate in a particular mode.

[0096] Such machine-readable instructions may also be loaded onto a computer or other programmable data processing apparatus such that the computer or other programmable data processing apparatus performs a sequence of operations to generate a computer-implemented process, such that the instructions executed on the computer or other programmable device implement the function specified by the block(s) in the flowcharts and / or block diagrams.

[0097] Furthermore, the teachings herein may be embodied in the form of a computer program product, the computer program product being stored on a storage medium and having a plurality of instructions for causing a computing device to implement the methods recited in the embodiments of the present disclosure.

[0098] An element or step described in relation to one embodiment may be combined with or substituted by an element or step described in relation to another embodiment. Other variations to the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. A computer program can be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be interpreted as limiting their scope.

Claims

Claim 1 A computer-implemented method comprising: receiving an indication of a weight on a movable support of a treatment table assembly, wherein the movable support is movable relative to a treatment table frame of the treatment table assembly; determining a horizontal shift of the treatment table frame relative to an imaging device associated with the treatment table assembly as a function of the weight of the indication on the movable support and a horizontal position of the movable support relative to the treatment table frame based on a shift model indicative of the horizontal shift; A method having the above steps. Claim 2 The receiving step of claim 1, further comprising receiving an indication of an expected position for moving the movable support to an expected position relative to the treatment table frame to provide the movable support at a specified position relative to the imaging device, and determining the horizontal shift relative to the expected position. Claim 3 The method of claim 2, further comprising moving the movable support to a corrected position determined based on a difference between the expected position and the horizontal shift such that the movable support is provided at the specified position. Claim 4 The method of claim 3, wherein moving the movable support to the corrected position includes causing a movable support actuator of the treatment table assembly to move the movable support to the corrected position. Claim 5 The method of claim 4, wherein moving the movable support to the corrected position includes generating a command for causing the movable support actuator to move the movable support to the corrected position and transmitting the command to the movable support actuator to cause operation of the movable support actuator in accordance with the command. Claim 6 The method of claim 4, wherein the movable support actuator is configured to move the movable support horizontally relative to a surface supporting the treatment table assembly such that the movable support is provided at the specified position. Claim 7 The method of claim 1, wherein the indication of the weight includes an indication of a current supplied to a treatment table frame actuator of the treatment table assembly, and the treatment table frame actuator is configured to control a height of the movable support relative to a surface supporting the treatment table assembly. Claim 8 The method according to claim 7, wherein the treatment table frame actuator is configured to maintain the movable support at a specific height during horizontal movement of the movable support relative to the treatment table frame.

9. Receiving the indication of the weight by receiving the indication of the current; Estimating the weight by using a vertical force balance model of the current required to provide the movable support at a specified height; Receiving a command specifying an expected position at which the movable support moves relative to the treatment table frame; Determining an expected shift of the treatment table frame according to the shift model based on the estimated weight and the expected position; Generating a modified command specifying a modified position at which the movable support is moved relative to the treatment table frame based on a difference between the expected position and the expected shift relative to the expected position; The method according to claim 7, comprising:

10. The method according to claim 1, wherein the shift model is determined from a set of measured values of the horizontal shift and a corresponding set of indicated values for the horizontal position of the movable support at which the horizontal shift is measured.

11. The method according to claim 10, wherein the shift model is based on a linear function fitted to a set of measured values of the horizontal shift and a corresponding set of indicated values of the horizontal position of the movable support.

12. The method according to claim 10, wherein the shift model is determined from a set of indicated values of the horizontal position of the movable support for each indicated value of a set of indicated values of the weight on the movable support.

13. A tangible machine-readable medium having instructions that, when executed by at least one processor, cause the at least one processor to execute the method according to any one of claims 1 to 12.

14. At least one processor communicatively coupled to an interface configured to receive an indication of a weight on a movable support of a treatment table assembly, wherein the movable support is movable relative to a treatment table frame of the treatment table assembly; A tangible machine-readable medium storing instructions readable and executable by the at least one processor, the instructions comprising: Receiving the indication of the weight; Determining a horizontal shift of the treatment table frame relative to an imaging device associated with the treatment table assembly as a function of a weight indicated on the movable support and a horizontal position of the movable support relative to the treatment table frame, based on a shift model indicative of the horizontal shift; A tangible machine-readable medium having instructions for performing a method; An apparatus having... **Claim 15** The interface further... Receiving an indication of an expected position to which the movable support is to be moved relative to the treatment table frame, in order to provide the movable support at a specified position relative to the imaging device; and Transmitting a command to a movable support actuator of the treatment table assembly, the command being configured to cause the movable support actuator to actuate; Configured to perform... The instructions further being instructions readable and executable by the at least one processor, Receiving an indication of the expected position; Determining the horizontal shift relative to the expected position; Moving the movable support to a corrected position determined based on a difference between the expected position and the horizontal shift, such that the movable support is provided at the indicated position, the moving being performed by generating a command configured to move the movable support to the corrected position to the movable support actuator and transmitting the command to the movable support actuator via the interface to cause actuation of the movable support actuator in accordance with the command; The apparatus according to claim 14, having instructions for performing a method.

Images