A real-time human posture tracking and calibration system for tumor radiotherapy

Abstract

The present invention discloses a real-time human body posture tracking and calibration device and system for tumor radiotherapy, which can replace the traditional treatment bed of a linear accelerator. For tumor target areas such as the head and neck that do not move with breathing, the changes in the online skin contour and the static position of the tumor are tracked. For chest and abdominal tumors that are greatly affected by breathing, the changes in the online skin contour are first tracked, and then the displacement of the tumor target area that moves in real time with breathing is compensated. A posture adjustment matrix composed of multiple independently adjustable support components is used to finally achieve real-time tracking and calibration of the posture of the human body or tumor target area with more than 6 degrees of freedom.

Description

Technical Field

[0001] The invention belongs to the technical field of tumor radiotherapy, and in particular relates to a real-time human body posture tracking and calibration system for tumor radiotherapy. Background Art

[0002] Radiotherapy is a treatment method that uses high-energy rays to irradiate malignant tumors to inhibit their growth and cause death. The basic principle of radiotherapy is to destroy malignant tumors and preserve normal tissues.

[0003] At present, before radiotherapy is given to patients in clinical practice, a body position fixation device such as thermoplastic film, foam glue or vacuum bag is used to fix the tumor part of the patient's body to prevent the irradiated part of the body from moving during irradiation, thereby ensuring that the target area is accurately irradiated. However, the above-mentioned fixation devices have the following problems during application:

[0004] First, with the progress of radiotherapy and other concurrent treatments such as chemotherapy, patients often become emaciated, lose weight, and their body contour volume shrinks irregularly. At this time, traditional body position fixing devices such as thermoplastic molds, foam glue or vacuum bags often have gaps with the human body surface and cannot achieve good fit or wrapping. At this time, the position of the human body or tumor target area is poorly fixed through the cross-line positioning on the surface of the fixing device. On the one hand, the present invention adjusts the support components in the fixing device by tracking the changes in the outer contour of the human skin to achieve calibration of the human body posture during radiotherapy.

[0005] In addition, affected by factors such as respiratory movement, patients undergoing radiotherapy for thoracic and abdominal tumors will inevitably experience some changes in body position or tumor autonomous or involuntary changes between different radiotherapy fractions and during a single radiotherapy, which will cause changes in the position of the tumor target area and affect the position accuracy of radiation irradiation during radiotherapy.

[0006] At this time, the clinical practice often adopts the method of expanding the irradiation field so that the movement range of the tumor is within the radiation field, thereby ensuring that the tumor does not go off target. However, this method will increase the irradiation dose of normal tissues, increase the probability of normal tissue complications, and may affect the patient's quality of life. On the other hand, in order to monitor the spatial position of the tumor target area on the human body surface or inside in real time, 4DCBCT, 4DMR, real-time ultrasound, optical surface guidance or electromagnetic guidance systems are currently used in clinical practice. When the above systems detect that the tumor position is "off target" or out of the radiation field range, the ray stops emitting beams, and when the tumor target area position returns to the radiation field, the ray starts to continue emitting beams, that is, gated radiotherapy technology; however, this method has low ray utilization efficiency, long patient treatment time, 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 used for positioning error calibration can currently achieve a maximum of six dimensions of adjustment. Before radiotherapy is implemented, the position deviation of the tumor target area can be monitored using image guidance technology, and the treatment bed can be corrected online. The six-dimensional treatment bed has linear motion in the three directions of x, y, and z and rotational motion around the three directions of x, y, and z. The patient's position can be adjusted from the six degrees of freedom to correct the above position error. However, this adjustment is based on the fact that the position fixing device can stably fix the patient's position. If the external contour of the human body changes irregularly to varying degrees, it is difficult to achieve accurate adjustment of the patient's position with the six-dimensional bed, and it is impossible to achieve the purpose of accurately irradiating the tumor target area. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a real-time human body posture tracking and calibration system for tumor radiotherapy, which can achieve the purpose of accurately irradiating the tumor target area. By tracking the real-time position changes of the tumor target area, through real-time adjustment of the support component, the position of the human body's center of mass is corrected to achieve real-time displacement compensation of the tumor target area, thereby achieving accurate irradiation of the tumor.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A real-time human posture tracking and calibration system for tumor radiotherapy comprises: a posture reconstruction device, a posture control device, a posture tracking device and a U-shaped base; wherein, retractable support rods are arranged in a matrix on the U-shaped base to form a support matrix, a stepping drive motor is provided at the bottom of the retractable support rod, and the telescopic length of the retractable support rod is accurately controlled by a screw rod; the upper end of the retractable support rod is connected to a non-metallic circular abutting ball holder, the abutting ball holder is wrapped by a silicone layer, and contains non-metallic material that can be detected by a millimeter detector at the end of the bed; a millimeter wave detector is provided at the end of the treatment bed, and the millimeter wave detector can scan all the abutting ball holders by emitting millimeter waves to detect the spatial position of each ball holder; a supporting gear is provided under the U-shaped base, and the gear rotates to drive the U-shaped base to realize rotation on the cross section of the base.

[0010] Preferably, the real-time human posture tracking and calibration system for tumor radiotherapy is used for positioning of the head, neck, chest, abdomen or limbs throughout the body.

[0011] Preferably, the posture reconstruction device is used to acquire 4DCT images or CT positioning images during simulated positioning CT scanning, and calculate the height information of the supporting ball holder corresponding to the position of the support rod in the support matrix based on the spatial coordinate value of each pixel point in the 4DCT image or the CT positioning image.

[0012] Preferably, after the height information of the supporting ball holders of all support rods in the support matrix is ​​transmitted to the posture control device, the control device controls each driving motor in the support matrix, and each motor drives the supporting column to extend or retract a corresponding length, pushing the supporting ball holder at the end of the supporting column to rise, so that all the supporting ball holders reach a predetermined height.

[0013] Preferably, in the online body surface tracking, the posture tracking device detects the supporting ball holder through a millimeter wave detector, that is, detects the height spatial position information corresponding to the position of the supporting ball holder connected to all the support rods in the support matrix, and uses the spatial position information of the supporting ball holder in contact with the human body to reconstruct the outer contour of part of the virtual human body and obtain the position of the geometric center of mass of the outer contour of the virtual human body; the height spatial position information corresponding to the position of the supporting ball holder of all the support rods in the support matrix calculated by the posture reconstruction device is used for position verification, and 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;

[0014] The posture control device is used to control the U-shaped base to rotate at an angle or move forward and backward by gear drive, correct the rotation deviation of the positioning and the error in the direction of the head and feet, and then the support matrix changes the telescopic length of the support rod based on the spatial position deviation of the supporting ball holder under the drive of the motor, that is, adjusts the position of the supporting ball holder.

[0015] Preferably, the posture reconstruction device segments the skin contour based on the real-time online image information of the patient obtained by the real-time online image guidance device; wherein the posture reconstruction device rigidly aligns the segmented CT image skin contour with the simulated positioning image skin contour to obtain the patient's rotational deviation and the error data of the head and feet direction; the posture reconstruction device simultaneously reads the spatial coordinate value of each pixel point of the CT image skin contour, and then uses the spatial position of each voxel point of the received real-time body surface contour to calculate the spatial position information of all the supporting ball holders that can contact the human body, and then obtains the spatial position deviation of each supporting ball holder reconstructed from the initial posture.

[0016] Preferably, the real-time spatial position information of each voxel point of the patient's tumor target area is monitored by a real-time online image guidance device, and the posture reconstruction device segments the contour of the tumor target area and obtains the geometric centroid displacement vector field of the real-time tumor contour;

[0017] The displacement of the tumor target area is compensated by the posture tracking device;

[0018] The posture tracking device calculates the real-time motion vector field of each supporting ball in the support matrix based on the geometric center of mass displacement vector field of the virtual outer contour of the human body; the real-time lifting and lowering displacements of all supporting ball holders are compensated for the geometric center of mass displacement of the real-time tumor contour to ultimately achieve real-time tracking and calibration of the human body posture.

[0019] Preferably, the displacement compensation of the tumor target area position is performed by the posture tracking device as follows: the geometric center of mass of the virtual human body outer contour is calculated, and the virtual human body outer contour is detected by the posture tracking device through the millimeter wave detector and reconstructed; based on the geometric center of mass displacement vector field of the tumor contour, the motion compensation displacement vector field of the center of mass when it is relatively stationary is calculated, and then the displacement vector field of the geometric center of mass of the virtual outer contour is calculated to compensate for the change in the position of the tumor target area.

[0020] The present invention can adjust the patient's body position in real time during radiotherapy without expanding the irradiation field. The real-time displacement compensation of the outer contour of the human skin and the tumor target area ensures that the tumor target area is always located within the irradiation field, reduces normal tissue side effects, improves the efficiency of linear accelerator treatment, and ensures the patient's treatment effect. When using this system and device to implement radiotherapy, the production of traditional body position fixing devices is no longer necessary. Simulation positioning CT scanning also no longer requires complex body position fixing devices, and tumor patients can meet the positioning requirements of radiotherapy. This device and system can replace the treatment bed of the traditional linear accelerator (which only moves in four or six dimensions), and ultimately achieves real-time tracking and calibration of the body position of the human body or tumor target area with more than 6 degrees of freedom through a matrix-distributed and independently adjustable support assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a posture tracking and adjustment device for a real-time human posture tracking and calibration system for tumor radiotherapy;

[0023] Figure 2A schematic diagram of the support component structure of the real-time human posture tracking and calibration system for tumor radiotherapy;

[0024] Figure 3 This is a workflow diagram of the real-time human posture tracking and calibration system for tumor radiotherapy according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Embodiment 1:

[0028] The embodiment of the present invention provides a real-time human posture tracking and calibration system for tumor radiotherapy, including: a posture reconstruction device, a posture control device, a posture tracking device and a U-shaped base. Figure 1 , 2 As shown, the retractable support rods are arranged in a matrix on the U-shaped base to form a support matrix. The bottom of the retractable support rods is provided with a stepper drive motor, and the telescopic length of the retractable support rods is accurately controlled by a screw rod; the upper end of the retractable support rod is connected to a non-metallic circular support ball holder, which is wrapped with a silicone layer and contains non-metallic materials that can be detected by the millimeter detector at the end of the bed. A millimeter wave detector is provided at the end of the treatment bed. The millimeter wave detector can scan all the support balls and detect the spatial position of each ball holder by emitting millimeter waves; a support gear is provided under the U-shaped base, and the gear rotates to drive the U-shaped base to rotate on the cross section of the base. The real-time human posture tracking and calibration system for tumor radiotherapy can be used for positioning of the head, neck, chest, abdomen or limbs throughout the body; among them, it is divided into area A (head and neck area), area B (chest, abdomen and pelvis area), and area C (lower limb area), and the support matrix density of area A and area C is relatively higher.

[0029] The implementation of the real-time human posture tracking and calibration system for tumor radiotherapy is divided into three stages:

[0030] Phase 1: Pose Data Analysis

[0031] First, during the simulated positioning CT scan, tumor patients will collect 4DCT images (thoracic and abdominal tumors) or conventional CT positioning images (head and neck tumors or pelvic tumors). The above image data are transmitted to the posture reconstruction device to automatically or manually segment the skin outer contour and the tumor three-dimensional volume contour; for 4DCT images, after the tumor three-dimensional volume contour is segmented, the tumor geometric center of mass displacement vector field of multiple phases can be obtained.

[0032] Then, the coordinate reconstruction of the human body posture support matrix is ​​performed. In order to establish the CT spatial coordinate system, three lead points, namely Mark points, are attached to the body surface during clinical CT positioning scanning so that they can be identified on the CT image. Based on the Mark points, the image space coordinate origin (x=0, y=0, z=0) can be determined. The pixel coordinates of the patient's body surface outer contour (mainly the lower surface of the human body) corresponding to the Mark point in the y direction are (x=0, y=y', z=z'). The support matrix in the device of the present invention will also set a matrix origin in the corresponding partition (A, B, C) according to the tumor site. The position and height information of the supporting ball support at the end of the matrix origin support rod will match the spatial position information of the body surface contour (mainly the lower surface of the human body) pixel corresponding to the current patient's CT image space coordinate origin, that is, the coordinates of the supporting ball support at the end of the matrix origin support rod are (x=0, y=y', z=z'). At this point, the support matrix coordinate reconstruction is completed.

[0033] Then, the posture reconstruction device reads the spatial coordinate value of each pixel point of the skin outer contour (mainly the lower surface of the human body) in the CT image, and then calculates the height information of the support ball corresponding to the position of the support rod in the support matrix. The above information is transmitted to the posture control device at the same time. At this point, the posture data analysis stage is completed.

[0034] Phase 2: Pose support matrix reconstruction

[0035] After the height information of the supporting ball holders of all support rods in the support matrix is ​​transmitted to the posture control device, the control device controls each driving motor in the support matrix. Each motor drives the supporting column to extend or retract a corresponding length, pushing the supporting ball holder at the end of the supporting column to rise, so that all the supporting ball holders reach a predetermined height.

[0036] At this point, the posture support matrix reconstruction based on the patient's CT positioning scan image is completed.

[0037] Phase 3: Online body surface tracking

[0038] According to the conventional process of radiotherapy, after target area delineation and planning (for chest and abdominal tumors, if a 4DCT scan is performed, the time-weighted median image can be used for planning and design, and conventional CT positioning images can be used for planning and design for head and neck or pelvic tumors), the patient enters the linear accelerator room and begins positioning before treatment. After the second stage of posture support matrix reconstruction is completed, the patient can lie flat or lie flat on the support ball of the support matrix according to the position of CT simulation positioning. At this time, the patient basically achieves the position during simulation positioning.

[0039] First, the posture tracking device detects the supporting ball holder through the millimeter wave detector, that is, detects the height spatial position information corresponding to the position of the supporting ball holder connected to all the support rods in the support matrix. 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's outer contour and obtain the position of the geometric center of mass of the virtual human body's outer contour; the height spatial position information corresponding to the position of the supporting ball holder of all the support rods in the support matrix calculated by the posture reconstruction device is used for position verification, and 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 for adjustment until the two match. At this point, the posture reconstruction based on the simulated positioning CT image is completed.

[0040] Then, the patient's real-time online image information is monitored by a real-time online image guidance device such as conventional CBCT, 4DCBCT, 4DMR or real-time ultrasound. The image data is then transmitted to the posture reconstruction device for automatic or manual segmentation of the skin contour, and then the following two processes are started:

[0041] On the one hand, the posture reconstruction device rigidly aligns the skin contour of the segmented CT image with the skin contour of the simulated positioning image to obtain the rotational deviation of the patient's positioning and the error data of the head and feet direction.

[0042] On the other hand, the posture reconstruction device simultaneously reads the spatial coordinate value of each pixel point of the skin outer contour of the CT image, and then uses the spatial position of each voxel point of the received real-time body surface outer contour to calculate the spatial position information of all the supporting ball holders that can contact the human body, and then obtains the spatial position deviation of each supporting ball holder reconstructed from the initial posture.

[0043] Then, the posture reconstruction device transmits the position deviation data obtained from the above two aspects to the posture control device. The posture control device starts the following control process:

[0044] The U-shaped base is controlled by gear drive to rotate or move forward and backward to correct the rotation deviation of the position and the error of the head and feet direction. Then, the support matrix is ​​driven by the motor to change the telescopic length of the support rod based on the spatial position deviation of the support ball, that is, to adjust the position of the support ball. At this point, the tracking and calibration of the human body posture based on the outer contour of the human skin is completed;

[0045] At the same time, real-time online image guidance devices such as 4DCBCT, 4DMR or real-time ultrasound monitor the real-time spatial position information of each voxel point in the patient's tumor target area, and the posture reconstruction device segments the contour of the tumor target area and obtains the geometric center of mass displacement vector field of the real-time tumor contour.

[0046] Then, the position tracking device performs displacement compensation on the tumor target area. The process is as follows: First, the geometric centroid of the virtual human body outer contour is calculated. The virtual human body outer contour is detected by the position tracking device through the millimeter wave detector and reconstructed. Then, based on the geometric centroid displacement vector field of the tumor contour, the motion compensation displacement vector field of the centroid when it is relatively stationary is calculated, and then the displacement vector field of the geometric centroid of the virtual outer contour is calculated to compensate for the change in the position of the tumor target area.

[0047] Then, the posture tracking device calculates the real-time motion vector field of each supporting ball in the support matrix based on the geometric center of mass displacement vector field of the virtual outer contour of the human body. The real-time lifting displacement of all supporting balls is compensated by the geometric center of mass displacement of the real-time tumor contour to finally achieve real-time tracking and calibration of the human body posture.

[0048] There are two scenarios for real-time calibration in the embodiment of the present invention:

[0049] 1. When the spatial position of lung, liver or breast tumors in the chest and abdomen changes with breathing due to respiratory movement; the embodiment of the present invention ensures that the target area is always within the radiation field range through real-time correction of the human body position. At present, clinical practice can only ensure that the tumor target area will not be off target when moving with breathing by expanding the radiation field range, so as to ensure that the tumor is given sufficient radiation. The expanded radiation field range will cause more normal tissues around the tumor, such as lung tissue or liver tissue, to be surrounded by the radiation field range, which may cause more normal tissue complications. The embodiment of the present invention can reduce the radiation field range as much as possible, and offset or reduce the relative movement range of the tumor as much as possible by adjusting the human body position in real time, thereby reducing the radiation dose of normal tissues and reducing normal tissue complications. It should be noted that when the spatial position of the tumor changes with breathing and other movements, the outer contour of the human body often does not change involuntarily at this time. The embodiment of the present invention connects the position change information of the tumor inside the human body with the positioning device, and uses the support and abutment ball holder arranged in the system matrix to change the human body position in real time, so that the spatial position of the tumor and the range of the irradiation field are relatively fixed.

[0050] 2. For the relatively rigid human tissues of the head and neck, the tumor usually does not move with breathing during radiotherapy, so it is only necessary to ensure the initial radiotherapy positioning accuracy. When implementing this technology, it is only necessary to track and adjust the outer contour of the skin and the static tumor position. Compared with the flat base, the U-shaped base of the embodiment of the present invention can match the curved contour of the side of the human body, and can achieve a better wrapping positioning effect.

[0051] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A real-time human posture tracking and calibration system for tumor radiotherapy, characterized in that: include: A posture reconstruction device, a posture control device, a posture tracking device and a U-shaped base; wherein, the retractable support rods are arranged in a matrix on the U-shaped base to form a support matrix, and a stepping drive motor is provided at the bottom of the retractable support rods, and the telescopic length of the retractable support rods is accurately controlled by a screw rod; the upper end of the retractable support rod is connected to a non-metallic circular supporting ball holder, the supporting ball holder is wrapped with a silicone layer, and contains non-metallic materials that can be detected by the millimeter detector at the end of the bed; a millimeter wave detector is provided at the end of the treatment bed, and the millimeter wave detector can scan all the supporting ball holders by emitting millimeter waves to detect the spatial position of each ball holder; a supporting gear is provided under the U-shaped base, and the gear rotates to drive the U-shaped base to realize the rotation of the cross section of the base; In the online body surface tracking, the posture tracking device detects the supporting ball holder through the millimeter wave detector, that is, detects the height spatial position information corresponding to the position of the supporting ball holder connected to all the support rods in the support matrix, and uses the spatial position information of the supporting ball holder in contact with the human body to reconstruct the outer contour of part of the virtual human body and obtain the position of the geometric center of mass of the outer contour of the virtual human body; the height spatial position information corresponding to the position of the supporting ball holder of all the support rods in the support matrix calculated by the posture reconstruction device is used for position verification, and the spatial position deviation of each ball holder in the matrix is ​​calculated, and then the spatial position deviation is transmitted to the posture control device; The posture control device is used to control the U-shaped base to rotate or move forward and backward by gear drive, correct the rotation deviation of the position and the error of the head and feet direction, and then the support matrix changes the telescopic length of the support rod based on the spatial position deviation of the supporting ball holder under the drive of the motor, that is, adjusts the position of the supporting ball holder; The posture reconstruction device segments the skin contour according to the real-time online image information of the patient obtained by the real-time online image guidance device; wherein, the posture reconstruction device rigidly aligns the segmented CT image skin contour with the simulated positioning image skin contour to obtain the patient's rotational deviation and the error data of the head and feet direction; the posture reconstruction device simultaneously reads the spatial coordinate value of each pixel point of the CT image skin contour, and then uses the spatial position of each voxel point of the received real-time body surface contour to calculate the spatial position information of all the supporting ball holders that can contact the human body, and then obtains the spatial position deviation of each supporting ball holder reconstructed from the initial posture; The real-time spatial position information of each voxel point in the patient's tumor target area is monitored by a real-time online image guidance device, and the posture reconstruction device segments the contour of the tumor target area and obtains the geometric center of mass displacement vector field of the real-time tumor contour; The displacement of the tumor target area is compensated by the posture tracking device; The posture tracking device calculates the real-time motion vector field of each supporting ball in the support matrix based on the geometric center of mass displacement vector field of the virtual outer contour of the human body; the real-time lifting and lowering displacements of all supporting ball holders are compensated for the geometric center of mass displacement of the real-time tumor contour to ultimately achieve real-time tracking and calibration of the human body posture.

2. The real-time human posture tracking and calibration system for tumor radiotherapy according to claim 1, characterized in that: The real-time human posture tracking and calibration system for tumor radiotherapy is used for positioning of the head, neck, chest, abdomen or limbs throughout the body.

3. The real-time human posture tracking and calibration system for tumor radiotherapy according to claim 2, characterized in that: The posture reconstruction device is used to acquire 4DCT images or CT positioning images during simulated positioning CT scanning, and calculate the height information of the supporting ball support corresponding to the position of the support rod in the support matrix according to the spatial coordinate value of each pixel point in the 4DCT image or the CT positioning image.

4. The real-time human posture tracking and calibration system for tumor radiotherapy according to claim 3, characterized in that: After the height information of the supporting ball holders of all support rods in the support matrix is ​​transmitted to the posture control device, the posture control device controls each drive motor in the support matrix. Each drive motor drives the support column to extend or retract a corresponding length, pushing the supporting ball holder at the end of the support column to rise, so that all the supporting ball holders reach a predetermined height.

5. The real-time human posture tracking and calibration system for tumor radiotherapy according to claim 4, characterized in that: The displacement compensation of the tumor target area position by the posture tracking device is specifically performed as follows: the geometric center of mass of the virtual human body outer contour is calculated, and the virtual human body outer contour is detected by the posture tracking device through the millimeter wave detector and reconstructed to obtain the position of the ball holder; based on the geometric center of mass displacement vector field of the tumor contour, the motion compensation displacement vector field of the center of mass when it is relatively stationary is calculated, and then the virtual outer contour geometric center of mass displacement vector field is calculated to compensate for the change in the tumor target area position.

Images