Real-time human body pose tracking and calibration system for tumor radiotherapy

Abstract

Disclosed in the present invention are a real-time human body pose tracking and calibration device and system for tumor radiotherapy, which can replace conventional linear accelerator couches. For tumor target regions that do not displace with respiration, such as the head and neck, the present invention tracks online the changes of the outer contour of skin and the static position of a tumor; and for thoracic and abdominal tumors that are significantly affected by respiration, the present invention first tracks online the changes of the outer contour of skin, and then performs displacement compensation on a tumor target region which moves along with respiration in real time. A pose adjustment matrix consisting of a plurality of independently-adjustable support components can finally realize real-time human body pose tracking and calibration with more than six degrees of freedom for a human body or a tumor target region.

Description

A tumor radiotherapy real-time human body position tracking and calibration system TECHNICAL FIELD

[0001] The present application belongs to the technical field of tumor radiotherapy, and particularly relates to a tumor radiotherapy real-time human body position tracking and calibration system. BACKGROUND

[0002] Radiotherapy is a therapy for inhibiting the growth of malignant tumors and killing them by using high-energy rays, and is referred to as radiotherapy. The basic principle of radiotherapy is to destroy malignant tumors and preserve normal tissues.

[0003] At present, before radiotherapy is performed on a patient, a body position fixing device such as a thermoplastic film, foaming glue or a vacuum bag is used to fix the tumor part of the patient's body, so as to prevent the irradiated part of the human body from moving during irradiation, thereby ensuring that the target area is accurately irradiated. However, the above fixing device has the following problems in the application process:

[0004] Firstly, as radiotherapy and other concurrent treatments such as chemotherapy are performed, the patient often appears to be emaciated, the body weight is reduced, and the irregular volume of the body surface contour is reduced. At this time, the traditional body position fixing device such as a thermoplastic film, foaming glue or a vacuum bag often appears to have a gap with the body surface, and cannot achieve good fitting or wrapping. At this time, the position of the human body or the tumor target area is fixed to be poor through the cross line positioning on the surface of the fixing device. The present application adjusts the support assembly in the fixing device by tracking the change of the human body skin contour, so as to realize the calibration of the human body position during radiotherapy.

[0005] In addition, due to the influence of respiratory motion and other factors, the chest and abdominal tumor radiotherapy patients still inevitably appear some changes in body position or tumors during different fraction radiotherapy and single radiotherapy process, which leads to the change of the position of the tumor target area, and affects the position accuracy of the ray irradiation during radiotherapy.

[0006] At this time, the clinic often adopts the way of expanding the irradiation field to make the moving range of the tumor located in the field, so as to ensure that the tumor does not miss the target, but this way will cause the normal tissue to increase the dose, increase the probability of normal tissue complications, and may affect the quality of life of the patient. On the other hand, in order to monitor the spatial position of the tumor target area on the surface or inside the human body in real time, the current clinic uses 4DCBCT, 4DMR, real-time ultrasound, optical surface guidance or electromagnetic guidance systems, when the above systems monitor that the tumor position "misses the target" that is out of the field, the rays stop out of the beam, and when the tumor target area position returns to the field, the rays continue to open and out of the beam, that is, the gating radiotherapy technology; However, this way has low utilization efficiency of the rays, long treatment time of the patient, poor treatment compliance, and affects the treatment effect. In addition, the treatment bed equipped with the linear accelerator can also be used to correct the positioning error. The existing treatment bed for positioning error correction can realize the adjustment of six dimensions at most, the position deviation of the tumor target area can be monitored by using the image guided technology before the implementation of radiotherapy, and the treatment bed can be corrected online. The six-dimensional treatment bed has linear motion in x, y and z directions and rotation around x, y and z directions, and the patient position can be adjusted from 6 degrees of freedom, and the above position error can be corrected. However, this adjustment is based on the stable fixation of the patient position by the body position fixing device, if the human body contour changes irregularly to different degrees, the application of the six-dimensional bed is also difficult to realize the accurate adjustment of the patient position, and the purpose of accurately irradiating the tumor target area cannot be achieved.

[0007] SUMMARY

[0008] The technical problem to be solved by the present application is to provide a tumor radiotherapy real-time human body position tracking and calibration system, which can achieve the purpose of accurately irradiating the tumor target area, track the real-time position change of the tumor target area, correct the position of the human body center of gravity through the real-time adjustment of the supporting assembly, realize the real-time displacement compensation of the tumor target area, and further realize the accurate irradiation of the tumor.

[0009] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0010] A tumor radiotherapy real-time human body position tracking and calibration system, comprising: a position reconstruction device, a position control device, a position tracking device and a U-shaped base; wherein the telescopic support rods are arranged in a matrix on the upper surface of the U-shaped base to form a support matrix, the bottom of the telescopic support rod is provided with a stepping motor, and the telescopic length of the telescopic support rod is accurately controlled through a lead screw; the upper end of the telescopic support rod is connected with a non-metallic circular supporting ball holder, the outside of the supporting ball holder is wrapped with a silica gel layer, and the inside of the supporting ball holder has a non-metallic material that can be detected by a millimeter detector at the tail of the treatment bed; the tail of the treatment bed is provided with a millimeter wave detector, the millimeter wave detector can scan all the supporting ball holders by emitting millimeter waves, and detect the spatial position of each ball holder; the U-shaped base is provided with a supporting gear below, and the gear rotates to drive the U-shaped base to rotate in the horizontal cross section of the base.

[0011] As preferred, the tumor radiotherapy real-time human body position posture tracking and calibration system is used for positioning of the head and neck, chest, abdomen or limbs all over the body.

[0012] As preferred, the posture reconstruction device is used for acquiring 4DCT images or CT positioning images collected during simulation positioning CT scanning, and calculating the height information of the supporting ball holder corresponding to the position of the supporting rod in the support matrix according to the spatial coordinate values of each pixel point in the 4DCT images or CT positioning images.

[0013] As preferred, after the height information of the supporting ball holder of all supporting rods in the support matrix is transmitted to the posture control device, the control device controls each drive motor in the support matrix, each motor drives the corresponding length of the supporting column to extend or retract, pushes the supporting ball holder at the end of the supporting column to rise, and makes all the supporting ball holders reach the predetermined height.

[0014] As preferred, in the online body surface tracking, the posture tracking device detects the supporting ball holder through the millimeter wave detector, i.e. detects the height spatial position information corresponding to the position of the supporting ball holder connected to all the supporting rods in the support matrix, and the spatial position information of the supporting ball holder in contact with the human body can be used to reconstruct part of the virtual human body outer contour and obtain the position of the virtual human body outer contour geometric centroid; the position of the height spatial position information of the supporting ball holder corresponding to the position of all the supporting rods in the support matrix calculated by the posture reconstruction device is rechecked, the spatial position deviation of each ball holder in the matrix is calculated, and then the deviation data information is transmitted to the posture control device.

[0015] The posture control device is used for controlling the U-shaped base to rotate or move forward and backward in the direction of the gear drive cooperation, correcting the rotational deviation of the positioning and the error in the head and foot direction, and then the support matrix changes the extension length of the supporting rod based on the spatial position deviation of the supporting ball holder under the drive of the motor, i.e. adjusts the position of the supporting ball holder.

[0016] As preferred, the posture reconstruction device segments the skin outer contour according to the real-time online image information obtained by the real-time online image guiding device; wherein the posture reconstruction device performs rigid registration on the segmented CT image skin outer contour and the skin outer contour of the simulation positioning image to obtain the rotational deviation of the patient positioning and the error data in the head and foot direction; the posture reconstruction device simultaneously reads the spatial coordinate values of each pixel point of the CT image skin outer contour, and then calculates the spatial position information of all the supporting ball holders that can contact the human body by using the received spatial position of each voxel point of the real-time body surface outer contour, and then obtains the spatial position deviation of each supporting ball holder reconstructed by the initial posture.

[0017] As preferred, the real-time spatial position information of each voxel point of the tumor target region of the patient is monitored by the real-time online image guiding device, the tumor target region contour is segmented by the pose reconstruction device, and a geometric centroid displacement vector field of the real-time tumor contour is obtained;

[0018] The tumor target region position is displaced by the pose tracking device;

[0019] The pose tracking device calculates a real-time motion vector field of each supporting ball holder in the support matrix based on the geometric centroid displacement vector field of the virtual outer contour of the human body, and the real-time lifting displacement of all supporting ball holders is finally realized by the geometric centroid displacement compensation of the real-time tumor contour to realize the real-time tracking and calibration of the human body pose.

[0020] As preferred, the displacement compensation of the tumor target region position by the pose tracking device is specifically: the geometric centroid of the virtual human body outer contour is calculated, the virtual human body outer contour is obtained by the pose tracking device by detecting the position of the supporting ball holder through the millimeter wave detector; the motion compensation displacement vector field of the centroid relative to the static state is calculated based on the geometric centroid displacement vector field of the tumor contour, and the virtual outer contour geometric centroid displacement vector field is calculated to compensate the displacement of the tumor target region position change

[0021] The present application can realize the real-time body position adjustment of the patient during radiotherapy, without the need to expand the irradiation field, through the real-time displacement compensation of the outer contour of the human body and the tumor target region to ensure that the tumor target region is always located in the field region, reduce the normal tissue side reaction, improve the treatment efficiency of the linear accelerator, and ensure the treatment effect of the patient. When the present system and device are used for radiotherapy, the traditional body position fixing device is no longer needed. When the simulation positioning CT scan is performed, the complex body position fixing device is also no longer needed, and the tumor patient can realize the positioning requirement of radiotherapy. The present device and system can replace the treatment bed (only four or six dimensions of movement) of the traditional linear accelerator, and finally realize the real-time tracking and calibration of the body position or the tumor target region with more than six degrees of freedom through the matrix distributed independently adjustable supporting components. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0023] Fig. 1 is a structure schematic view of the pose tracking and adjustment device of the real-time human body pose tracking and calibration system for tumor radiotherapy;

[0024] Fig. 2 is a schematic diagram of a support assembly structure of a tumor radiotherapy real-time human body position tracking and calibration system;

[0025] Fig. 3 is a workflow diagram of the tumor radiotherapy real-time human body position tracking and calibration system according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0027] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0028] Embodiment 1

[0029] The tumor radiotherapy real-time human body position tracking and calibration system according to an embodiment of the present application comprises a position reconstruction device, a position control device, a position tracking device and a U-shaped base. As shown in Figs. 1 and 2, the telescopic support rods are arranged in a matrix on the U-shaped base to form a support matrix. The bottom of each telescopic support rod is provided with a stepper motor for accurately controlling the extension length of the telescopic support rod through a screw rod. The upper end of each telescopic support rod is connected to a non-metallic circular supporting ball holder. The supporting ball holder is wrapped with a silica gel layer on the outside and contains a non-metallic material that can be detected by a millimeter probe at the tail of a treatment bed. The tail of the treatment bed is provided with a millimeter wave probe. The millimeter wave probe can scan all the supporting ball holders and detect the spatial position of each ball holder by emitting millimeter waves. The U-shaped base is provided with a support gear below. The rotation of the gear drives the rotation of the U-shaped base in the horizontal cross section of the base. The tumor radiotherapy real-time human body position tracking and calibration system can be used for positioning the head and neck, chest, abdomen or limbs. The system is divided into an A area (head and neck area), a B area (chest and abdominal and pelvic area) and a C area (lower limb area). The support matrix density is relatively higher in the A area and the C area.

[0030] The implementation of the tumor radiotherapy real-time human body position tracking and calibration system is divided into three stages.

[0031] First stage: position data analysis

[0032] Firstly, the tumor patient will collect 4DCT image (chest and abdominal tumor) or regular CT positioning image (head and neck tumor or pelvic tumor) when simulating positioning CT scanning. The above image data is transmitted to the pose reconstruction device, and the skin outer contour and tumor three-dimensional volume contour are automatically segmented or manually segmented. For 4DCT image, the tumor three-dimensional volume contour is segmented to obtain the displacement vector field of the tumor geometric centroid of multiple phases.

[0033] Then, the human body pose support matrix coordinate reconstruction is performed. In order to establish the CT space coordinate system, three lead points, i.e. Mark points, are pasted on the body surface during clinical CT positioning scanning, so as to be recognized on the CT image. Based on the Mark points, the image space coordinate origin (x=0, y=0, z=0) can be determined. In the y direction, the pixel point coordinates of the patient's body surface contour (mainly the lower surface of the human body) corresponding to the Mark points are (x=0, y=y', z=z'). The support matrix in the device will also set a matrix origin according to the tumor site in the corresponding partition (A, B, C). The position and height information of the supporting ball holder at the end of the matrix origin support rod will match the space position information of the body surface contour (mainly the lower surface of the human body) pixel corresponding to the CT image space coordinate origin of the current patient, i.e. the coordinates of the supporting ball holder at the end of the matrix origin support rod are (x=0, y=y', z=z'). Thus, the support matrix coordinate reconstruction is completed.

[0034] Then, the pose reconstruction device reads the space coordinate value of each pixel point of the CT image skin outer contour (mainly the lower surface of the human body), and then calculates the height information of the supporting ball holder corresponding to the position of the support rod in the support matrix. The above information is transmitted to the pose control device. Thus, the pose data analysis stage is completed.

[0035] Second stage: pose support matrix reconstruction

[0036] After the height information of the supporting ball holder of all support rods in the support matrix is transmitted to the pose control device, the control device controls each drive motor in the support matrix, each motor drives the support column to stretch and retract the corresponding length, pushes the supporting ball holder at the end of the support column to rise, and makes all the supporting ball holders reach the predetermined height.

[0037] At this time, the pose support matrix reconstruction based on the CT positioning image of the patient is completed.

[0038] Third stage: online body surface tracking

[0039] According to the conventional procedure of radiotherapy, after the target area is outlined, the plan is designed (for thoracic and abdominal tumors, if 4DCT scanning is performed, time-weighted median images can be used for plan design, and for head and neck or pelvic tumors, conventional CT positioning images can be used for plan design), and other links, the patient enters the linear accelerator room, and the pre-treatment positioning is started. After the second stage of position support matrix reconstruction is completed, the patient can lie or lie on the support matrix of the supporting ball according to the CT simulation positioning position. At this time, the patient basically realizes the body position of the simulation positioning.

[0040] Firstly, the position tracking device detects the supporting ball through the millimeter wave detector, that is, detects the height space position information corresponding to the position of the supporting ball connected with all the supporting rods in the support matrix. The space position information of the supporting ball in contact with the human body can be used to reconstruct part of the virtual human body contour and obtain the position of the virtual human body contour centroid. The position of the height space position information corresponding to the position of the supporting ball of all the supporting rods in the support matrix calculated by the position reconstruction device is checked, the space position deviation of each ball in the matrix is calculated, and then the deviation data information is transmitted to the position control device for adjustment until the two are consistent. At this time, the positioning position reconstruction based on the simulation positioning CT image is completed.

[0041] Then, the real-time online image guiding device such as conventional CBCT, 4DCBCT, 4DMR or real-time ultrasound is used to monitor and obtain the real-time online image information of the patient. The image data is transmitted to the position reconstruction device again, the skin contour is automatically segmented or manually segmented, and then the following two processes are started:

[0042] On the one hand, the position reconstruction device performs rigid registration on the segmented CT image skin contour and the skin contour of the simulation positioning image, and obtains the rotation deviation of the patient positioning and the error data of the head and foot direction.

[0043] On the other hand, the position reconstruction device reads the space coordinate value of each pixel point of the CT image skin contour, and then calculates the space position information of all the supporting balls in contact with the human body by using the received space position of each voxel point of the real-time body surface contour, and then obtains the space position deviation of each supporting ball reconstructed by the initial position.

[0044] Then, the position reconstruction device transmits the position deviation data obtained in the above two aspects to the position control device. The position control device starts the following control process:

[0045] The control U-shaped base is driven to rotate or move forward and backward by gear drive matching, the rotational deviation and the head and foot direction error of the positioning are corrected, and then the support matrix changes the extension length of the support rod based on the spatial position deviation of the ball holder under the driving of the motor, that is, the position of the ball holder is adjusted.

[0046] Meanwhile, the real-time spatial position information of each voxel point of the tumor target region of the patient is monitored by a real-time online image guiding device such as 4DCBCT, 4DMR or real-time ultrasound, the tumor target region contour is segmented by the pose reconstruction device, and the geometric centroid displacement vector field of the real-time tumor contour is obtained.

[0047] Then, the tumor target region position is displaced by the pose tracking device, and the process is as follows: first, the virtual human external contour geometric centroid is calculated, the virtual human external contour is obtained by the pose tracking device by detecting the position of the ball holder through the millimeter wave detector. Then, the motion compensation displacement vector field of the geometric centroid of the tumor contour is calculated based on the geometric centroid displacement vector field of the tumor contour, and then the virtual external contour geometric centroid displacement vector field is calculated to displace the tumor target region position change.

[0048] Then, the pose tracking device calculates the real-time motion vector field of each ball holder in the support matrix based on the geometric centroid displacement vector field of the virtual human external contour. The real-time lifting displacement of all ball holders is finally realized through the geometric centroid displacement compensation of the real-time tumor contour to realize the real-time tracking and calibration of the human pose.

[0049] There are two scenarios for real-time calibration in the embodiment of the application:

[0050] 1. When the spatial position of the tumor in the chest and abdomen, such as the lung, liver or breast, changes with respiration, the embodiment of the application ensures that the target region is always within the field of view by real-time correction of the human position. Currently, the only way to ensure that the tumor target region does not miss the target when moving with respiration is to expand the field of view, so as to ensure that the tumor receives enough radiation. The expanded field of view will result in more normal tissues such as lung tissue or liver tissue being wrapped in the field of view, which may cause more normal tissue complications. The embodiment of the application can minimize the field of view as much as possible, and offset or minimize the relative movement range of the tumor by real-time adjustment of the human position, thereby reducing the dose of normal tissues and reducing normal tissue complications. It should be noted that when the spatial position of the tumor changes with movement such as respiration, the external contour of the human body often does not change non-autonomously, and the embodiment of the application associates the internal tumor position change information with the positioning device, and changes the human position in real time by using the support and ball holder arranged in the system matrix, so as to relatively fix the spatial position of the tumor and the range of the field of view.

[0051] 2. For the relatively rigid tissues of the head and neck, the tumor usually does not shift with respiration during radiotherapy; only the initial radiotherapy positioning accuracy needs to be maintained. In this technique, only the outer contour of the skin and the static position of the tumor need to be tracked and adjusted. Compared to a planar base, the U-shaped base of this embodiment conforms to the curved contour of the human body, achieving a better positioning effect with better coverage.

[0052] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A real-time tumor radiotherapy patient position tracking and calibration system, comprising: The system comprises a pose reconstruction device, a pose control device, a pose tracking device and a U-shaped base; wherein the telescopic support rods are arranged in a matrix on the U-shaped base to form a support matrix, the bottom of the telescopic support rods is provided with a stepping drive motor, the telescopic length of the telescopic support rods is accurately controlled through a screw rod; the upper end of the telescopic support rods is connected with a non-metallic circular supporting ball holder, the outside of the supporting ball holder is wrapped with a silica gel layer, and the inside of the supporting ball holder is provided with a non-metallic material which can be detected by a millimeter detector at the tail of a treatment bed; the tail of the treatment bed is provided with a millimeter wave detector, the millimeter wave detector can scan all the supporting ball holders by emitting millimeter waves, and the spatial position of each ball holder is detected; a support gear is arranged below the U-shaped base, and the rotation of the gear drives the U-shaped base to rotate in the horizontal cross section of the base. The tumor radiotherapy real-time human body pose tracking and calibration system is used for positioning of the head and neck, chest, abdomen or limbs.

2. The real-time tumor radiotherapy human pose tracking and calibration system of claim 1, wherein, The pose reconstruction device is used for acquiring 4DCT images or CT positioning images collected during simulation positioning CT scanning, and calculating the height information of the supporting ball holders corresponding to the positions of the support rods in the support matrix according to the spatial coordinate values of each pixel point in the 4DCT images or CT positioning images.

3. The real-time tumor radiotherapy human pose tracking and calibration system of claim 2, wherein, After the height information of the supporting ball holders of all the support rods in the support matrix is transmitted to the pose control device, the control device controls each drive motor in the support matrix, each motor drives the support column to extend or retract by a corresponding length, pushes the supporting ball holder at the end of the support column to rise, and makes all the supporting ball holders reach a predetermined height.

4. The real-time tumor radiotherapy human pose tracking and calibration system of claim 3, wherein, In the online body surface tracking, the pose tracking device detects the supporting ball holders through the millimeter wave detector, that is, detects the height spatial position information corresponding to the positions of the supporting ball holders connected with all the support rods in the support matrix, and the spatial position information of the supporting ball holders in contact with the human body is used to reconstruct part of the virtual human body outer contour and obtain the position of the virtual human body outer contour geometric centroid; the height spatial position information corresponding to the positions of the supporting ball holders of all the support rods in the support matrix calculated by the pose reconstruction device is position reviewed, the spatial position deviation of each ball holder in the matrix is calculated, and then the deviation data information is transmitted to the pose control device; 5. The real-time tumor radiotherapy human pose tracking and calibration system of claim 4, wherein, The pose control device is used for controlling the U-shaped base to be driven by the gear to rotate at an angle or move forward and backward, correcting the rotational deviation of the positioning and the error in the head and foot directions, and then changing the telescopic length of the support rods based on the spatial position deviation of the supporting ball holders, that is, adjusting the positions of the supporting ball holders, under the drive of the motor. The pose reconstruction device segments the skin outer contour according to the real-time online image information of the patient obtained by the real-time online image guiding device; wherein the pose reconstruction device performs rigid registration on the segmented CT image skin outer contour and the skin outer contour of the simulation positioning image to obtain the rotational deviation of the patient positioning and the error data in the head and foot directions; the pose reconstruction device reads the spatial coordinate values of each pixel point of the CT image skin outer contour, then calculates the spatial position information of all the supporting ball holders in contact with the human body by using the received spatial position of each voxel point of the real-time body surface outer contour, and then obtains the spatial position deviation of each supporting ball holder reconstructed according to the initial pose.

6. The real-time tumor radiotherapy human pose tracking and calibration system of claim 5, wherein, ​ 7. The real-time tumor radiotherapy human pose tracking and calibration system of claim 6, wherein, The real-time spatial position information of each voxel point of the tumor target area of the patient is monitored by a real-time online image guiding device, a pose reconstruction device is used to segment the tumor target area contour, and a geometric centroid displacement vector field of the real-time tumor contour is obtained; The tumor target area position is displaced by a pose tracking device; The pose tracking device calculates the real-time motion vector field of each supporting ball holder in the support matrix based on the geometric centroid displacement vector field of the virtual outer contour of the human body, and the real-time lifting displacement of all supporting ball holders is finally realized by the geometric centroid displacement compensation of the real-time tumor contour, so that the real-time tracking and calibration of the human body pose are realized.

8. The real-time tumor radiotherapy human pose tracking and calibration system of claim 7, wherein, The displacement compensation of the tumor target area position by the pose tracking device is specifically as follows: a virtual human body outer contour geometric centroid is calculated, the virtual human body outer contour is obtained by detecting the position of the supporting ball holder by the pose tracking device through a millimeter wave detector; a motion compensation displacement vector field of the centroid relative to the static state is calculated based on the geometric centroid displacement vector field of the tumor contour, and then the virtual outer contour geometric centroid displacement vector field is calculated to displace the position change of the tumor target area.

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