Determining the shift of the 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 treatment table frame related to an imaging device.

Background Art

[0002] During a patient imaging operation, a movable support of a treatment table assembly can move a patient to a specified position so that an imaging device such as a computed tomography (CT) scanner can acquire imaging data at an imaging plane corresponding to a specified part of the patient's body.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, the accuracy of patient positioning with respect to the imaging plane can affect the result of the imaging operation. For example, if there is an error in the patient's position relative to the imaging plane, the imaging data may no longer correspond to the specified part of the patient. In some cases, it may be necessary to move the patient again so that the specified part of the patient is imaged, which can unnecessarily increase the patient's exposure to radiation and / or increase the time spent performing the imaging operation. In some cases, the error may not be recognized, which can lead to an inaccurate analysis of the imaging data. Errors in the patient's position relative to the imaging plane in the vertical direction are described in German Patent Application Publication No. 102007060690A1 and US Patent Application Publication No. 2016 / 0113598.

Means for Solving the Problems

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

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

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

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

[0008] In some embodiments, the method includes moving the movable support to a modified position (hereinafter referred to as the "modified position") determined based on the difference between the expected position and the horizontal shift, thereby providing the movable support to the designated position.

[0009] In some embodiments, moving the movable support to a correct position includes instructing the movable support actuator of the treatment table assembly to move the movable support to a correct position.

[0010] In some embodiments, moving a movable support to a correct position includes generating a command configured to cause the movable support actuator to move the movable support to the correct 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 with respect to the surface supporting the treatment table assembly, thereby providing the movable support to a designated position.

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

[0013] In some embodiments, the treatment table frame actuator is configured to maintain the movable support at a specific height during the horizontal movement of the movable support relative to the treatment table frame.

[0014] In some embodiments, the method includes receiving a weight indication by receiving an indication of current. The method may further include estimating the weight by using a vertical force equilibrium model of current required to provide a movable support at a specified height. The method may further include receiving a command specifying the expected position in which the movable support is moved relative to the treatment table frame. The method may further include determining a predicted shift of the treatment table frame according to a shift model based on the estimated weight and predicted position. The method may further include generating a revised or "modified" command to specify the modified position in which the movable support is moved relative to the treatment table frame based on the 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 horizontal shift and a corresponding set of markings for the horizontal position of the movable support on which the horizontal shift is measured.

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

[0017] In some embodiments, the shift model is determined from a set of markings for the horizontal position of the movable support for each marking in the set of markings for the weight on the movable support.

[0018] In a second aspect, a tangible machine-readable medium is described. The tangible machine-readable medium has instructions that, when executed by at least one processor, cause at least one processor to perform the 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 communicably coupled to an interface configured to receive a weight indication on a movable support of a treatment table assembly. The movable support is movable relative to the treatment table frame of the treatment table assembly. The apparatus further has a tangible machine-readable medium that stores instructions that are readable and executable by the at least one processor for performing a method. The method includes receiving a weight indication. The method further includes determining the horizontal shift of the treatment table frame relative to an imaging device associated with the treatment table assembly based on a shift model that shows the horizontal shift as a function of the weight indicated on the movable support and the horizontal position of the movable support relative to the treatment table frame.

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

[0021] In some embodiments, the interface is further configured to receive an indication of the desired position to which the movable support is to be moved with respect to the treatment table frame, in order 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 the movable support actuator of the treatment table assembly. The command can be configured to activate the movable support actuator. The instructions can further include instructions readable and executable by at least one processor for performing the method. The method includes receiving an indication of the desired position. The method can further include determining a horizontal shift relative to the desired position. The method can further include moving the movable support to a corrected position determined based on the difference between the desired position and the horizontal shift such that the movable support is provided at the specified position, the moving to the corrected position being performed by generating, by the movable support actuator, a command to move the movable support to the corrected position and sending the command, via the interface, to the movable support actuator to cause activation of the movable support actuator in accordance with the command.

[0022] These and other aspects of the invention will become apparent from the embodiments described below and will be described with reference thereto.

[0023] Brief Description of the Drawings Exemplary embodiments of the invention are described merely by way of example with reference to the following drawings:

Brief Description of the Drawings

[0024] [Figure 1] Schematic diagram of a scenario depicting an error in positioning of the movable support of a treatment table assembly, as referred to in various embodiments. [Figure 2] Diagram showing a method for determining a treatment table frame shift according to one embodiment. [Figure 3] Diagram showing a method for determining and correcting a treatment table frame shift according to various embodiments. [Figure 4]Schematic diagram depicting a model of a treatment table assembly for estimating weight. [Figure 5] Diagram showing a method for determining and correcting a treatment table frame shift according to one embodiment. [Figure 6] Graph showing a set of measured values of a treatment table frame shift as a function of the position of a movable support. [Figure 7] Graph showing a method for calculating the coefficients of a shift model according to one embodiment based on a curve fitted to the data of FIG. 6. [Figure 8] Schematic diagram of a machine-readable medium for determining a treatment table frame shift according to one embodiment. [Figure 9] Schematic diagram of an apparatus for determining and / or correcting a treatment table frame shift according to various embodiments.

Best Mode for Carrying Out the Invention

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

[0026] As shown in configuration (a), the subject 104 is placed on the movable support 106 of the treatment table assembly 100. The movable support 106 may be called a “table,” “tabletop,” or “treatment table (couch).” As shown in configuration (b), the movement of the movable support 106 from the position shown in configuration (a) positions the subject 104 within the imaging plane 108 associated with the imaging device 102. Thus, by moving the movable support 106 relative to the imaging plane 108, different parts 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 images at each of the axial positions.

[0027] The treatment table assembly 100 also has a treatment table frame 110 to support a movable support 106 and to facilitate the movement (e.g., horizontal movement) of the movable support 106 relative to the imaging device 102. The treatment table 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 specific distance (e.g., height) above a surface 112 such as the floor on which the treatment table assembly 100 is placed.

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

[0029] One end of each member 118 is pivotably connected to a base member 116, while the other end of each member 118 is pivotably mounted to the surface 112. The ends of the two members 118 pivotably 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 (for example, so that the base member 116 is parallel to the surface 112). Similarly, the other ends of the two members 118 pivotably mounted to the surface 112 are movably spaced apart from each other. The treatment table assembly 100 has a treatment table frame actuator 122 (e.g., an electric motor) configured to control / adjust the height of the patient 104 by causing the members 118 to move 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 treatment table frame actuator 122 is mounted to the surface 112 and is configured to apply force to one end of the members 118 mounted to the surface 112. The ends of the other members 118 attached to the surface 112 are secured in place, as indicated by the fixing mounts 124.

[0030] Therefore, during use, the treatment table frame actuator 122 applies force to member 118, bringing the ends of member 118 attached to the surface 112 closer together. This movement of member 118, through a lever motion around pivot 120, raises the base member 116, and thus raises the patient 104 as well. The weight W can be balanced using a specific force applied by the treatment table frame actuator 122. By changing this force, the patient 104 can be raised or lowered relative to the surface 112. If the treatment table frame actuator 122 has an electric motor, the current supplied to the electric motor can be changed to controllably adjust the height of the patient 104.

[0031] As emphasized above, the configuration of the scissor mechanism 114 and the relevant parts of the treatment table assembly 100 may differ from those shown and described in relation to Figure 1. For example, the two members 118 do not have to be configured in a scissor-like configuration as shown in Figure 1, and instead can move independently of each other (for example, the members 118 do not have to be connected to each other via the pivot 120). Furthermore, the number of members 118 may differ (for example, three or more members 118 may be used, or one member may be used). Furthermore, the configuration of the treatment table frame actuator 122 may also differ (for example, the treatment table frame actuator 122 may be connected to different parts of member 118, etc.).

[0032] Therefore, functionally, the treatment table assembly 100 is configured to facilitate height adjustment / control of the subject 104 while balancing the weight W, and as a result, the subject 104 can be provided at a specified height. Any configuration of the treatment table assembly 100 that facilitates such function may be related to the present disclosure.

[0033] The configuration shown in Figure 1 is schematic in order to better illustrate the possible components of the treatment table assembly 100, and therefore, please understand that the configuration and design of the components may differ from those shown in Figure 1.

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

[0035] The treatment table assembly 100 has a movable support actuator 126 for moving the movable support 106 relative to the treatment table frame 110. In this example, the movable support actuator 126 is mounted between the base member 116 and the movable support 106. During use, the movable support actuator 126 (electric motor, hydraulic system, etc.) applies force between the base member 116 and the movable support 106, causing relative motion between them. The movable support 106 is mounted on a sliding mechanism 128 (e.g., at least one roller) attached 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 communicably coupled to the movable support actuator 126, causing the movable support 106 to move a distance "L1", so that the end of the movable support 106 above the treatment table frame 110 is at the specified position 132 (meaning the subject 104 is provided at the specified position defined by the command L1_cmd). There may be an error (error) "err1" in the actual distance moved. Therefore, a correction mechanism such as a servo motor (not shown) can correct this error err1.

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

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

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

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

[0041] This greater force F2 results in additional pressure on the treatment table frame 110, accompanied by a corresponding horizontal shift of the treatment table frame 110. This results in movement of the treatment table frame 110 relative to the surface 112 toward the imaging device 102. In some cases, this pressure may also result in a (relatively small) reduction in the height of the treatment table frame 110. As shown in configuration (b), the position of the treatment table frame 110 is shifted by a distance L2 from its immediate position. In particular, the end of the base member 116 in configuration (a) is indicated by the 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 greater the force acting on the treatment table frame 110 due to the shift in the center of gravity, and the greater the lever effect acting on the scissor mechanism 114.

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

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

[0044] However, if the treatment table frame 110 is shifted as shown in configuration (b), a deviation / offset is 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 deviation / offset can affect the quality and / or outcome of the imaging operation. In some cases, the deviation may be such that additional images need to be acquired, which can unnecessarily increase the patient's exposure to radiation and / or increase the time spent performing the imaging operation. In some cases, errors may go unnoticed, which can lead to inaccurate analysis of the imaging data.

[0045] Currently, the deviation / offset of the treatment table frame 110 is not considered, and therefore a systematic error proportional to the travel distance L1 may be introduced. Embodiments described herein can facilitate the correction of this deviation / offset. For example, certain embodiments described herein can determine the treatment table frame shift. Certain embodiments can take actions to correct the determined treatment table frame shift.

[0046] Figure 2 shows a method 200 (e.g., a computer-implemented method) for determining the treatment table frame shift according to one embodiment. For a description of method 200, refer to Figure 1. Figure 1 shows a controller 130 capable of implementing method 200. The controller 130 can be implemented by a computer, such as a user computer, communicably coupled to a user interface, or by a server or cloud-based service (e.g., communicably coupled to a user computer and / or user interface). Thus, method 200 can be implemented on-site (e.g., on a user computer at the location of the treatment table assembly 100) or elsewhere (e.g., on a server or in the cloud). Commands and / or feedback are communicated between the controller 130 and the treatment table frame actuator 122 and / or the movable support actuator 126 to facilitate the implementation of a particular method (e.g., method 200) described herein.

[0047] Method 200 includes receiving a weight marking on the movable support 106 of the treatment table assembly 100 in block 202. The movable support 106 is movable relative to the treatment table frame 110 of the treatment table assembly 100. Further discussion regarding the weight marking is provided below.

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

[0049] Method 200 can enable the determination of the treatment table frame shift. Accordingly, corrections can be applied to the command L1_cmd to ensure that the subject 104 is provided to the specified position, as will be described in more detail below. For example, during an imaging operation, the operator can instruct the movable support 106 to move to a specified position (defined by a fixed point, such as the end of the movable support 106 provided to the specified position 132). However, to compensate for a treatment table frame shift, which could otherwise lead to the subject 104 being moved to an inaccurate (e.g., unexpected) position, the command can be modified to take into account the (expected) treatment table frame shift so that the subject 104 is moved to the correct position (e.g., the expected position or specified position).

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

[0051] Figure 3 shows various embodiments of method 300 (e.g., a computer-implemented method) for determining and correcting treatment table frame shift. Method 300 can be implemented in the same way as method 200 (e.g., using controller 130). For example, method 300 may have the same or similar functions as method 200. Refer to Figures 1 and 2 as needed. Some blocks of method 300 may not need to be implemented, and / or some blocks of method 300 may be executed in a different order than shown in Figure 3.

[0052] In some embodiments, method 300 includes, in block 302, receiving an indication of an expected position in which the movable support 106 is moved relative to the treatment table frame 110 in order to provide the movable support 106 to a designated position 132 relative to the imaging device 102 (302). The “expected position” may refer to the position in which the movable support 106 is moved (i.e., after the command L1_cmd is executed). The “expected position” is based on the assumption that the reference frame of the treatment table 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 the aforementioned shift into account. Therefore, method 300 further includes, in block 304, determining the shift with respect to the expected position (for example, according to method 200).

[0053] In some embodiments, method 300 includes moving the movable support 106 in block 306 to a corrected position determined based on the difference between the expected position and the shift, so that the movable support 106 is provided to the specified position 132 (i.e., as expected). Thus, the “corrected position” takes the shift L2 into account. In other words, if the treatment table 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 table frame 110 results in the movable support 106 being correctly provided to the specified position 132,).

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

[0055] In some embodiments, the method 300 for moving the movable support to a correct position according to block 308 includes, in block 310, generating a command for the movable support actuator 126 to move the movable support 106 to a correct position (for example, relative to a reference frame defined by the treatment table frame 110). Block 308 further includes, in block 312, transmitting the command to the movable support actuator 126 to actuate the movable support actuator 126 in accordance with the command.

[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, so that the movable support 106 (for example, the end of the movable support 106 overhanging the treatment table frame 110) is provided to a designated position 132.

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

[0058] In some embodiments, the weight indicator includes an indicator of the current supplied to the treatment table frame actuator 122.

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

[0060] Embodiments illustrating the estimation of weight (used to provide weight indications) are described in more detail below.

[0061] Figure 4 shows a simplified diagram of a treatment table assembly 400 similar to the treatment table assembly 100 shown in Figure 1. Reference numerals for features of treatment table assembly 400 that are the same as or similar to the corresponding features of treatment table assembly 100 are incremented by 300. Some features are not illustrated or described for the sake of illustration and refer to Figure 1 where necessary.

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

[0063] The treatment table frame actuator 422 is used to balance the vertical forces applied by the components and the weight of the patient. If the treatment table frame actuator 422 has an electric motor to apply force to balance the vertical forces, the current supplied to the electric motor can be changed accordingly. Based on current feedback, the weight W can be estimated using the following vertical force equilibrium 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] Here, θ is the interior angle between member 118 and surface 412, g is the gravity coefficient (constant), H is the height of the treatment table frame 110, h1 is the height of the base member 116 (subpallet), h2 is the height of the treatment table base 436 (not shown previously, but the top of the treatment table base 436 represents surface 112), F is the force applied to member 118 by the treatment table frame actuator 122, p is the screw lead associated with the screw driven by the treatment table frame actuator 122 (connecting member 118 to the treatment table frame actuator 122), T is the motor torque associated with the treatment table frame actuator 122, i is the transmission rate, and η e is the motor efficiency, KT is the motor torque coefficient, I is the current supplied to the treatment table frame actuator 122, R is half the length of member 118, and r is the radius of pivot 120.

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

[0066] Therefore, the weight can be estimated so that this weight indication can be used to determine the shift according to some of the methods described herein. Rather than having a separate sensor for measuring weight, certain embodiments can facilitate a simple method for estimating the weight.

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

[0068] Method 500 includes receiving a weight indication in block 502 by receiving an indication of current (for example, the current shown in Figure 4).

[0069] Method 500 further includes estimating the weight in block 504 by using a vertical force equilibrium model (as described, for example, in relation to Figure 4) of the current required to provide the movable support 106 at a specific height.

[0070] Method 500 further includes receiving a command (e.g., "L1_cmd") in block 506 that specifies the expected position to which the movable support 106 moves relative to the treatment table frame 110.

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

[0072] Method 500 further includes, in block 510, generating a modified command that specifies 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, we will explain how to determine the "shift model" used to determine the treatment table frame shift.

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

[0075] Therefore, in this example, there are six datasets, namely one dataset 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 of 0 to 1800 mm.

[0076] Figure 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 treatment table frame 110) for each of the six datasets. The steepest curve corresponds to the heaviest weight of 307 kg, and the gentlest curve corresponds 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 the proportionality constant (corresponding to the slope of the dataset as a function of weight W), P is the expected position of the movable support 106, and D(W) is the 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 illustrated dataset, the curve is fitted with a 95% confidence interval.

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

[0079] Figure 7 shows graphs plotting K(W) and D(W) as functions of weight W, as well as linear curves fitted to each variable. The confidence interval is 95%. In Figure 7, the positive slope represents K(W), and the negative slope represents D(W). Thus, when weight W is estimated as described above, the treatment table frame shift curve can be determined by obtaining K(W) and D(W) for the estimated weight (as functions of the expected position of the movable support 106). Thus, the values ​​K(W) and D(W) represent the “shift model” described above.

[0080] In other words, the “shift model” can be represented by a ratio coefficient and an offset fitted to a set of measurement data, the measurement data including actual measurements of the position of the movable support 106 (relative to the imaging device 102 or the “ground” reference frame) for each of the set of expected positions of the movable support 106 (for determining the “actual” shift). The measurement data can be scaled by weight so that the shift model is weight-dependent, for example, as indicated by the current described above.

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

[0082] To compensate for the shift determined according to the shift model, a command (e.g., "L1_cmd") can be modified based on the (expected) position of the movable support 106. For example, if a 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., if 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 that are otherwise generated and sent to the movable support actuator 126. In other words, a command received by the controller 130 to move the movable support 106 by a (expected) distance D1 can be modified by the difference between D1 and the (estimated) shift, i.e., D1 - S1.

[0083] Accordingly, certain embodiments described herein can compensate for movement errors caused by shift without adding additional sensors to the setup. In some embodiments, a force equilibrium model can be used to estimate the load or weight on the movable support 106. A shift model can be generated based on a set of measurements. The shift model can be used to estimate the treatment table frame shift for a given position of the movable support 106 at the estimated weight. Accordingly, certain embodiments can facilitate the correction of motion commands used to drive the movable support 106 to a specified position so that the subject 104 is positioned more accurately relative to the imaging device 102 (compared to when shift is not considered).

[0084] Figure 8 shows a tangible machine-readable medium 800 according to one embodiment. The tangible machine-readable medium 800, when executed on at least one processor 804, has instructions 802 that cause at least one processor 804 to implement several 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 that causes at least one processor 804 to implement such a method.

[0085] Figure 9 shows a device 900 for determining the treatment table frame shift according to various embodiments. The device 900 has at least one processor 902 (implemented, for example, by a controller 130 shown in Figure 1). The at least one processor 902 is communicably coupled to an interface 904 to communicate with the treatment table frame actuators 122 and / or the movable support actuators 126 (for example, to receive information such as current indications and / or to send commands to control the respective actuators 122, 126). In this embodiment, the interface 904 is configured to receive a weight indication on the movable support 106. As previously stated, the movable support 106 is movable relative to the treatment table frame 110 of the treatment table assembly 100. The interface 904 may be part of the controller 130 referenced in Figure 1, and specific features of the aforementioned figures are referenced in the description of the device 900.

[0086] The apparatus 900 further includes a tangible machine-readable medium 906 that stores instructions 908 that are readable and executable by at least one processor 902 for performing a method corresponding to one of the methods described herein (for example, any of methods 200, 300, and / or 500).

[0087] In one embodiment, instruction 908 is configured to cause at least one processor 902 to execute method 200.

[0088] In some embodiments relating to the above embodiments, interface 904 is further configured to receive an indication of an expected position in which the movable support 106 is moved to an expected position relative to the treatment table frame 110 in order to provide the movable support 106 to a designated position 132 relative to the imaging device 102. Interface 904 may be further configured to send a command to a movable support actuator 126 of the treatment table assembly 100. Such a command may be configured to actuate the movable support actuator 126. In such embodiments, instruction 908 may be configured to cause at least one processor 902 to execute method 300. In the context of device 900, method 300 includes receiving an indication of an expected position, determining a shift relative to the expected position, and moving the movable support 106 to a modified position determined based on the difference between the expected position and the shift, so that the movable support 106 is provided to the designated position 132. The “modified” command generated to move the movable support 106 is configured to move the movable support actuator 126 to move the movable support 106 to the modified position. The modified command is transmitted to the movable support actuator 126 via interface 904, causing the movable support actuator 126 to actuate according to the command.

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

[0090] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustrations and descriptions should be considered descriptive or illustrative and not limiting. The present invention is not limited to the disclosed embodiments.

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

[0092] Embodiments in this disclosure may be provided as methods, systems, or combinations of machine-readable instructions and processing circuits. Such machine-readable instructions may be contained on a non-temporary 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 in or over thereon.

[0093] This disclosure will be described with reference to flowcharts and block diagrams of methods, apparatus, and systems according to embodiments of this disclosure. While the flowcharts described above illustrate specific instruction execution sequences, the instruction execution sequences may differ from those illustrated. Blocks described in relation to one flowchart can be combined with blocks in another flowchart. It should be understood that each block in a flowchart and / or block diagram, and combinations of blocks in a flowchart and / or block diagram, can be implemented by machine-readable instructions.

[0094] Machine-readable instructions can be executed, for example, by a processor in a general-purpose computer, a dedicated computer, an embedded processor, or other field-programmable gate array data processing device to implement the functions described in the description and diagrams. In particular, a processor or processing circuit, or a module thereof, can execute machine-readable instructions. Thus, the functional modules of the devices and other devices described herein can be implemented by a processor that executes machine-readable instructions stored in memory, or by a processor that operates according to instructions embedded in a logic circuit. The term "processor" should be interpreted broadly to include CPUs, processing units, ASICs, logic units, or programmable gate arrays. All methods and functional modules can be executed by a single processor or divided among several processors.

[0095] Such machine-readable instructions can also be stored in a computer-readable storage device that can guide a computer or other field-programmable gate array data processing device to operate in a specific mode.

[0096] Such machine-readable instructions may also be loaded onto a computer or other programmable data processing device, which then performs a series of operations to generate computer-implemented processing, and so the instructions executed on the computer or other programmable device implement the function specified by the block(s) in the flowchart and / or block diagram.

[0097] Furthermore, the teachings herein may be implemented in the form of a computer program product, which is stored on a storage medium and has a number of instructions for a computer device to implement the methods enumerated in the embodiments of this disclosure.

[0098] Components or steps described in relation to one embodiment may be combined with or replaced by components or steps described in relation to another embodiment. Other variations of the disclosed embodiments may be understood and implemented by those skilled in the art in carrying out the claimed invention, based on a consideration of the drawings, disclosures, and appended claims. In the claims, the word “comprising” is not exclusive of other components or steps, and the indefinite article “a” or “an” is not exclusive of plural. A single processor or other unit may perform the functions of several items enumerated in the claims. The mere fact that certain means are described in mutually different dependent claims does not imply that combinations of these means cannot be used advantageously. Computer programs may be stored or distributed on suitable media such as optical storage media or solid-state media supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. No reference numeral in the claims should be construed as limiting its scope.

Claims

1. A method of realizing a computer A step of receiving a weight indication on a movable support of a treatment table assembly, wherein the movable support is movable relative to the treatment table frame of the treatment table assembly, A step of determining the horizontal shift of the treatment table frame relative to the imaging device associated with the treatment table assembly, based on a shift model that shows the horizontal shift as a function of the weight of the marking on the movable support and the horizontal position of the movable support relative to the treatment table frame, A method of having.

2. The method according to claim 1, comprising the steps of: receiving an indication of an expected position to move the movable support to an expected position relative to the treatment table frame in order to provide the movable support to a specified position relative to the imaging device; and determining the horizontal shift relative to the expected position.

3. The method of claim 2, further comprising the step of moving the movable support to a modified position determined based on the horizontal shift relative to the expected position, such that the movable support is provided to the designated position.

4. The method according to claim 3, wherein the step of moving the movable support to the corrected position includes instructing the movable support actuator of the treatment table assembly to move the movable support to the corrected position.

5. The method according to claim 4, wherein the step of moving the movable support to the corrected position includes generating a command for the movable support actuator to move the movable support to the corrected position, and transmitting the command to the movable support actuator to cause the movable support actuator to operate in accordance with the command.

6. The method according to claim 4, wherein the movable support actuator is configured to move the movable support horizontally with respect to the surface supporting the treatment table assembly so that the movable support is provided to the designated position.

7. The method according to claim 1, wherein the weight indication includes an indication of the current supplied to the treatment table frame actuator of the treatment table assembly, and the treatment table frame actuator is configured to control the height of the movable support with respect to the surface supporting the treatment table assembly.

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 the horizontal movement of the movable support relative to the treatment table frame.

9. The steps include receiving the indication of the current and receiving the indication of the weight, The steps include: estimating the weight by using a vertical force equilibrium model of the current required to provide the movable support at a specified height; The steps include receiving a command that specifies the expected position in which the movable support moves relative to the treatment table frame, The steps include determining the expected shift of the treatment table frame according to the shift model based on the estimated weight and the expected position, The steps include generating a modified command that specifies a modified position in which the movable support is moved relative to the treatment table frame, based on the difference between the expected position and the expected shift relative to the expected position, The method according to claim 7, having the following characteristics.

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 set of corresponding marked values ​​for the horizontal position of the movable support on 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 marked 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 markings for the horizontal position of the movable support for each marking value in the set of markings for the weight on the movable support.

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

14. At least one processor communicatively coupled to an interface configured to receive a weight indication on a movable support of a treatment table assembly, wherein the movable support is movable relative to the treatment table frame of the treatment table assembly, A tangible machine-readable medium storing instructions that are readable and executable by at least one processor, wherein the instructions are: The steps include receiving the weight indication, A step of determining the horizontal shift of the treatment table frame relative to the imaging device associated with the treatment table assembly, based on a shift model that shows the horizontal shift as a function of the weight marked on the movable support and the horizontal position of the movable support relative to the treatment table frame, An instruction to perform a method having a tangible machine-readable medium, A device having.

15. The aforementioned interface further, In order to provide the movable support at a specified position relative to the imaging device, the movable support receives an indication of the expected position to which it will move relative to the treatment table frame, and Sending a command to the movable support actuator of the treatment table assembly, wherein the command is configured to activate the movable support actuator. It is configured to do the following: The instruction is further an instruction that is readable and executable by the at least one processor, The steps include receiving the indication of the expected position, The steps include determining the horizontal shift relative to the expected position, A step of moving the movable support to a corrected position determined based on the horizontal shift relative to the expected position, such that the movable support is provided to the specified position, wherein the movement is performed by generating a command configured for the movable support actuator to move the movable support to the corrected position, and transmitting the command to the movable support actuator via the interface to cause the movable support actuator to act in accordance with the command. The apparatus according to claim 14, having an instruction to perform a method having

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