Claims:We claim
1. A method to calculate instantaneous values of hexapod couch along with iso centre and thereby implementing of patient positioning using 6-degrees hexapod couch to trace dynamic movements of target or tumor therein, the method comprising the steps of:
a. generating and locating origin on a hexapod model on a couch co-ordinate system (201);
b. initializing a first centre point to a hexapod’s bottom plate on a linear direction (i.e. Xci, Yci, Zci) (202);
c. shifting the hexapod model from the couch co-ordinate system to a radiotherapy machine co-ordinate system (203);
d. applying pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta) to a top plate of the hexapod (204);
e. locating a hexapod’s top plate centre point after applying the pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta) (205);
f. positioning a second centre point to the hexapod’s bottom plate (Xc,Yc,Zc) based on the top plate centre point location, wherein the bottom plate centre point location (Xc,Yc,Zc) is positioned by considering the pre-determined height below the top plate centre point location (206);
g. arranging the bottom plate of the hexapod to a horizontal co-ordinate plane (i.e. X axis) and a longitudinal co-ordinate plane (i.e. Y axis) after determining the centre point location therein, wherein the bottom plate is arranged to the X and Y axis by making a vertical co-ordinate plane (i.e. Z axis) to zero (207);
h. determining a new rotational or theta angle value by calculating a dot product of the bottom plate centre point (Xc, Yc, 0) on the negative Y-axis (208);
i. applying the calculated negative rotational angle value to bring the bottom plate centre point (Xc,Yc,Zc) to a new position (0,Yc,Zc) on the Y and Z plane in the negative Y axis (209);
j. determining a new shift value by calculating the difference between the new position (0, Yc, Zc)and the initial position (Xci, Yci, Zci) of the bottom plate centre point (210); and
k. applying the calculated rotational angle value and the shift value to the bottom plate of the hexapod to align with the top plate of the hexapod and thereby calculating the instantaneous values of a new hexapod position in 6-degrees of freedom to trace the dynamic movements of the target or tumor therein (211).

2. The method as claimed in claim 1, wherein the bottom plate centre point location is determined at pre-determined height of 100mm below the top plate centre point location.

3. A method to calculate the position of leg values in the patient positioning hexapod couch, the method comprising the steps of:
a. calculating one or more bottom-leg joint positions of the hexapod using a line-sphere intersection with respect to top-leg joint positions of the hexapod, wherein the top-leg joint positions of the hexapod are fixed and the bottom-leg joint positions are movable (301);
b. equating the radius of the sphere with the length of the legs at the top plate of the hexapod couch (302);
c. locating at-least two points on the line based on the sphere intersection therein (303); and
d. determining and calculating the shortest distance of two points from the bottom-leg joint position and thereby calculating each leg value of the bottom-leg joint position of the patient positioning hexapod couch (304).

4. The method as claimed in claim 1 and 3, wherein the method (200) calculates the bottom-leg joint positions of the hexapod based on the calculated instantaneous rotational angle values and the shift values, wherein the bottom-leg joint positions are calculated to align bottom plate with the top plate therein.
, Description:[0001] PREAMBLE TO THE DESCRIPTION:
[0002] The following specification particularly describes the invention and the manner in which it is to be performed:
[0003] DESCRIPTION OF THE INVENTION:
[0004] Technical field of the invention
[0005] The present invention relates to for a method to calculate instantaneous values of hexapod couch along with iso centre axis to trace dynamic movements of target or tumor therein. More particularly, the method locates the moving target or tumor with respect to the radiation beam in both translational and rotational motions.
[0006] Background of the invention
[0007] In radiotherapy or radiation treatment, very intense and precisely collimated doses of radiation are delivered to the target region in the body of a patient in order to treat or destroy lesions. The radiotherapy machines using patient positioning system has 6-Degrees of freedom (i.e. vertical, longitudinal, lateral, pitch, yaw/couch iso centric and roll). Typically, the target region is comprised of a volume of tumorous tissue. Radiation treatment requires an accurate spatial localization of the targeted lesions. Radiotherapy treatment requires an exact knowledge of the target position (tumor position) not only at the planning stage but also the actual treatment times. The goal of radiotherapy is to destroy as many cancer cells as possible without harming the surrounding healthy tissue therein. During radiotherapy treatment, the human or animal tissue needs to expose to ionizing radiation to kill the tumor cells therein. Tumors in the thoracic and abdominal regions are susceptible to motion during normal respiration. Treating these tumors require updated hexapod couch positions that does not restrict point to point movement to trace dynamic movements of target or tumor therein.
[0008] Various types of conventional methods and systems that compensates the hexapod couch movement to track the treatment target in a patient are known in the prior art. The United States Patent 8542797 B2 describes a radiotherapy apparatus configured to track a motion of a target region using a combination of a multi-leaf collimator and a patient support. The cited document provides a radiotherapy apparatus for applying therapeutic radiation to a target region of a patient. The position of a target region is determined and resolved into two components orthogonal to the radiation beam axis. One component is assigned to the patient support, and the other to the collimator leaves, such that movement of the target region is compensated for and the radiation beam intersects is correctly targeted.
[0009] The European Patent document 1874388 A2 describes a technique for compensating movement of a treatment target in a patient. In the cited document, during the delivery of treatment, a state of the patient is measured to produce real-time measurement data. Measuring the state is non-invasive; and the measured state is a correlated surrogate for position of the target site. Compensating movement data is determined based on the real-time measurement data to cause the target site to maintain a particular spatial relationship with the treatment delivery device. Either the treatment delivery device, or the support structure, or both, are moved based on the compensating movement data. When the delivery device alone is moved, the correlation between measured state and target site is based on partial least squares applied to pre-treatment measurements of both.
[0010] The United States Patent document 9616251 B2 describes an imaging based calibration systems, devices, and methods. In the cited document, the system relates to an imaging-based calibration for accurate target positioning and localization.
[0011] The European Patent document 1907057 B1 describes a radiation therapy delivery device utilizing coordinated motion of gantry and couch. In the cited document, the treatment plan is delivered using a radiation therapy system. The system includes a moveable support for supporting a patient. The support and gantry are moved during delivery of the treatment plan.
[0012] Various types of conventional methods and systems that compensates the hexapod couch movement to track the treatment target in a patient are known in the prior art. In conventional radiotherapy machines, the hexapod couches are restricted to point to point movement to track and position the target tumor with an image guidance aligned to the beam line. Conventional methods do not calculate the instantaneous values of the hexapod couch in linear directions (i.e. in XYZ planes) along with the isocentre axis upon movement of translational direction of the hexapod couch. In conventional systems, the hexapod couch moves only from current position to the predefined position based on the Image-Guided Radiation Therapy (IGRT) system. Conventional systems do not trace the path from initial position to final position and also do not display the instantaneous values during the path. In convention radiation treatment, the radiotherapy beam is restricted in rotational motions (i.e. in pitch, yaw and roll) during the hexapod couch motions.
[0013] Hence, there is a need for a method to calculate instantaneous values of hexapod couch along with iso centre axis to trace dynamic movements of target or tumor therein. More particularly, the method locates the moving target or tumor with respect to the radiation beam in both translational and rotational motions.
[0014] Summary of the invention:
[0015] The present invention overcomes the drawbacks in the prior art and provides a method to calculate instantaneous values of hexapod couch along with iso centre and thereby implementing of patient positioning using 6-degrees hexapod couch to trace dynamic movements of target or tumor therein. In a preferred embodiment, the method includes the steps of generating and locating origin on a hexapod model on a couch co-ordinate system. After generating the origin on the hexapod model, a first centre point is initialized to a hexapod’s bottom plate on a linear direction (i.e. Xci, Yci, Zci). The hexapod model is shifted from the couch co-ordinate system to a radiotherapy machine co-ordinate system. After shifting, pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta) are applied to a top plate of the hexapod. The hexapod’s top plate centre point is located after applying the pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta). After locating the hexapod’s top plate centre point, a second centre point is positioned to the hexapod’s bottom plate (Xc,Yc,Zc) based on the top plate centre point location. The bottom plate centre point location (Xc,Yc,Zc) is positioned by considering the pre-determined height below the top plate centre point location. The bottom plate centre point location is determined at pre-determined height of 100mm below the top plate centre point location. The bottom plate of the hexapod is arranged on a horizontal co-ordinate plane (i.e. X axis) and a longitudinal co-ordinate plane (i.e. Y axis) after determining the centre point location therein. The bottom plate is arranged to the X and Y axis by making a vertical co-ordinate plane (i.e. Z axis) to zero. After arranging the bottom plate of the hexapod on the X and Y axis, a new rotational or theta angle value is determined by calculating a dot product of the bottom plate centre point (Xc, Yc, 0) on the negative Y-axis. The calculated negative rotational angle value is appplied to bring the bottom plate centre point (Xc,Yc,Zc) to a new position (0,Yc,Zc) on the Y and Z plane in the negative Y axis. A new shift value is determined by calculating the difference between the new position (0, Yc, Zc) and the initial position (Xci, Yci, Zci) of the bottom plate centre point. Finally, the calculated rotational angle value and the shift value is applied to the bottom plate of the hexapod to align with the top plate of the hexapod and thereby calculating the instantaneous values of a new hexapod position in 6-degrees of freedom to trace the dynamic movements of the target or tumor therein.
[0016] In another embodiment of the invention, the method calculates the position of leg values in the patient positioning hexapod couch. In a preferred embodiment of the invention, the method includes the steps of calculating one or more bottom-leg joint positions of the hexapod using a line-sphere intersection with respect to top-leg joint positions of the hexapod, wherein the top-leg joint positions of the hexapod are fixed and the bottom-leg joint positions are movable. After calculating the bottom-leg joint positions of the hexapod, the radius of the sphere is equated with the length of the legs at the top plate of the hexapod couch. Two points are locating on the line based on the sphere intersection therein. Finally, the shortest distance of two points from the bottom-leg joint position determined and calculated and thereby calculating each leg value of the bottom-leg joint position of the patient positioning hexapod couch.
[0017] The present invention provides a method, which is simple and is suitable for the applications in all kinds of radiotherapy machines.
[0018] It is to be understood that both the foregoing general description and the following details description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
[0019] Brief description of the drawings:
[0020] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0021] Figure 1 shows a perspective view of a hexapod couch, according to one embodiment of the invention.
[0022] Figure 2 illustrates the steps involved in calculating the instantaneous values of hexapod couch along with iso centre and thereby implementing of patient positioning using 6-degrees hexapod couch to trace dynamic movements of target or tumor therein, according to one embodiment of the invention.
[0023] Figure 3 illustrates the steps involved in calculating the position of leg values in the patient positioning hexapod couch, according to one embodiment of the invention.
[0024] Detailed description of the invention:
[0025] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0026] The present invention provides A method to calculate instantaneous values of hexapod couch along with iso centre and thereby implementing of patient positioning using 6-degrees hexapod couch to trace dynamic movements of target or tumor therein. The method locates the moving target or tumor with respect to the radiation beam in both translational and rotational motions. The hexapod couch enables point to point movement to track and position the target tumor with an image guidance aligned to the beam line.
[0027] Figure 1 shows a perspective view of a hexapod couch, according to one embodiment of the invention. In a preferred embodiment, the hexapod couch model (100) includes a top plate (101) and a bottom plate (102) and six legs (103). The top plate (101) and a bottom plate (102) are connected through the legs. The hexapod model (100) is generated at origin in the couch coordinate system. The top plate (101) and bottom plate (102) are represented by box shapes and defined by its 8 corner points and one box center point. Here, the top-leg joint positions (103a) of the hexapod are fixed and the bottom-leg joint positions (103b) are movable.
[0028] Figure 2 illustrates the steps involved in calculating the instantaneous values of hexapod couch along with iso centre and thereby implementing of patient positioning using 6-degrees hexapod couch to trace dynamic movements of target or tumor therein, according to one embodiment of the invention. In a preferred embodiment, the method includes the steps of generating and locating origin on a hexapod model on a couch co-ordinate system, at step (201). After generating the origin on the hexapod model, a first centre point is initialized to a hexapod’s bottom plate on a linear direction (i.e. Xci, Yci, Zci), at step (202). The hexapod model is shifted from the couch co-ordinate system to a radiotherapy machine co-ordinate system, at step (203). After shifting, pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta) are applied to a top plate of the hexapod, at step (204). The hexapod’s top plate centre point is located after applying the pre-defined input shifts (X,Y,Z) and rotational angle values (Pitch, Roll, Theta), at step (205). After locating the hexapod’s top plate centre point, a second centre point is positioned to the hexapod’s bottom plate (Xc,Yc,Zc) based on the top plate centre point location. The bottom plate centre point location (Xc,Yc,Zc) is positioned by considering the pre-determined height below the top plate centre point location. The bottom plate centre point location is determined at pre-determined height of 100mm below the top plate centre point location, at step (206). The bottom plate of the hexapod is arranged on a horizontal co-ordinate plane (i.e. X axis) and a longitudinal co-ordinate plane (i.e. Y axis) after determining the centre point location therein. The bottom plate is arranged to the X and Y axis by making a vertical co-ordinate plane (i.e. Z axis) to zero, at step (207). After arranging the bottom plate of the hexapod on the X and Y axis, a new rotational or theta angle value is determined by calculating a dot product of the bottom plate centre point (Xc, Yc, 0) on the negative Y-axis, at step (208). The calculated negative rotational angle value is appplied to bring the bottom plate centre point (Xc,Yc,Zc) to a new position (0,Yc,Zc) on the Y and Z plane in the negative Y axis, at step (209). A new shift value is determined by calculating the difference between the new position (0, Yc, Zc) and the initial position (Xci, Yci, Zci) of the bottom plate centre point, at step (210). Finally, at step (211), the calculated rotational angle value and the shift value is applied to the bottom plate of the hexapod to align with the top plate of the hexapod and thereby calculating the instantaneous values of a new hexapod position in 6-degrees of freedom to trace the dynamic movements of the target or tumor therein.
[0029] Figure 3 illustrates the steps involved in calculating the position of leg values in the patient positioning hexapod couch, according to one embodiment of the invention. In a preferred embodiment, the method includes the steps of calculating one or more bottom-leg joint positions of the hexapod using a line-sphere intersection with respect to top-leg joint positions of the hexapod. The top-leg joint positions of the hexapod are fixed and the bottom-leg joint positions are movable, at step (301). After calculating the bottom-leg joint positions of the hexapod, the radius of the sphere is equated with the length of the legs at the top plate of the hexapod couch, at step (302). Two points are locating on the line based on the sphere intersection therein, at step (303). Finally, at step (304), the shortest distance of two points from the bottom-leg joint position determined and calculated and thereby calculating each leg value of the bottom-leg joint position of the patient positioning hexapod couch.
[0030] The present invention provides a method, which is simple and is suitable for the applications in all kinds of radiotherapy machines.