CN100551465C

CN100551465C - A method for automatic positioning of patient's target area in radiotherapy

Info

Publication number: CN100551465C
Application number: CNB2006101579996A
Authority: CN
Inventors: 包尚联; 黄斐增; 谢耀新; 姬长国; 崔智�
Original assignee: HAISIWEI SCIENCE AND TECHNOLOGY Co Ltd BEIJING; Haibo Technology Co Ltd Shenzhen
Current assignee: HAISIWEI SCIENCE AND TECHNOLOGY Co Ltd BEIJING; Haibo Technology Co Ltd Shenzhen
Priority date: 2006-12-25
Filing date: 2006-12-25
Publication date: 2009-10-21
Anticipated expiration: 2026-12-25
Also published as: CN101209368A

Abstract

The invention discloses the automatic localized method of patient target region in a kind of radiotherapy, this method utilizes light source and flat panel detector to obtain the view data of patient target region around the patient target region rotation sweep, use virtual PI line algorithm for reconstructing that data are rebuild and handled, obtain the image of patient target region; By the result who compares with input image data, adjust patient's position, treat.Owing to adopt true 3D image reconstruction algorithm based on flat panel detector, the spatial resolution of true 3-D view is isotropic, do not need to carry out interpolation, can directly realize treatment of picture at three dimensions, therefore the accuracy and the precision of imaging have been improved greatly, solved when patient target region is located automatically in the existing radiotherapy, because of in being integrated into the process of quasi-three-dimensional images, causing the imaging inaccuracy and then influencing the accurate location of focus and the problem of the accurate execution of treatment plan owing to the interpolated error reason.

Description

A method for automatic positioning of patient's target area in radiotherapy

技术领域 technical field

本发明涉及一种病人定位的方法，尤其是涉及一种控制病人靶区定位的方法。The invention relates to a method for positioning a patient, in particular to a method for controlling the positioning of a patient's target area.

背景技术 Background technique

远距离立体定向放射治疗主要分为60Co立体定向放疗和电子直线加速器立体定向放疗两大类。在放疗过程影响放疗治疗效果的诸多因素中，对病人的摆位、治疗中心位置的确定以及对治疗过程中病人的运动(不由自主的运动、脏器运动带动的靶区运动)的控制是实施精确和影像导引放疗的关键，也是今后放疗设备中重点要解决的关键技术问题。越是精确的大剂量放疗，这方面的要求越高。Stereotactic radiotherapy is mainly divided into two categories: 60Co stereotactic radiotherapy and electron linear accelerator stereotactic radiotherapy. Among the many factors that affect the effect of radiotherapy during radiotherapy, the positioning of the patient, the determination of the location of the treatment center, and the control of the patient's movement (involuntary movement, target movement driven by organ movement) during the treatment process are the most important factors for accurate implementation. The key to image-guided radiotherapy and image-guided radiotherapy is also the key technical problem to be solved in radiotherapy equipment in the future. The more precise the high-dose radiotherapy, the higher the requirements in this regard.

随着科学技术的进步，主要是快速成像技术的进步，使得放疗过程从制定放疗计划开始到实施计划的全过程，以及计划实施之后对实施情况的评价都能以CT图像为主要信息源，具有个体特性的数据集为基础。这些技术的实施，大大提高了肿瘤治疗的准确性和疗效，是整个放疗领域的发展方向。除了CT成像提供的人体解剖学信息外，人体代谢、血流等生理参数，尤其是肿瘤靶区及其附件组织内的这些生理参数都已经能够被准确测定，这些数据提供了基于体素的肿瘤及其周围组织的生物活性的真实信息，这些信息不仅对肿瘤的正确分型和分期关系重大，对判断肿瘤内部结构也具有非常重要的意义(例如定义坏死区、泛氧区和高度浸润区等)。这些信息也应该被归纳到对肿瘤治疗中心位置的选择和治疗计划的精确确定之中。With the advancement of science and technology, mainly the advancement of rapid imaging technology, the whole process of radiotherapy from the formulation of the radiotherapy plan to the implementation of the plan, as well as the evaluation of the implementation after the plan is implemented, can use CT images as the main source of information. Data sets based on individual characteristics. The implementation of these technologies has greatly improved the accuracy and curative effect of tumor treatment, which is the development direction of the entire field of radiotherapy. In addition to the human anatomy information provided by CT imaging, physiological parameters such as human metabolism and blood flow, especially in the tumor target area and its accessory tissues, have been accurately measured. These data provide a voxel-based tumor This information is not only important for the correct classification and staging of tumors, but also has a very important significance for judging the internal structure of tumors (for example, defining necrotic areas, pan-oxygenated areas, and highly infiltrating areas, etc. ). This information should also be incorporated into the selection of tumor treatment center locations and the precise determination of treatment plans.

现有放射治疗中采用的成像技术如美国断层放疗技术专利(US6438202)中描述的是用断层成像的技术实现的，这种技术把肿瘤病灶及其周围组织分割到不同断层切片(slice)上，断层内部的信息被求了平均之后，丢掉了病灶及其周围组织的某些信息不可能再恢复，把切片整合成准三维图像的过程中，由于内插误差原因而造成了图像不精确，进而影响病灶的精确定位和治疗计划的准确性。The imaging technology used in the existing radiation therapy is realized by the technology of tomography as described in the American tomotherapy technology patent (US6438202). This technology divides the tumor lesion and its surrounding tissues into different slices. After the information inside the slice is averaged, some information about the lesion and its surrounding tissue is lost and cannot be restored. In the process of integrating the slices into a quasi-three-dimensional image, the image is inaccurate due to interpolation errors, and then It affects the precise location of the lesion and the accuracy of the treatment plan.

发明内容 Contents of the invention

本发明提供一种放射治疗中病人靶区自动定位的方法，以解决现有放射治疗中病人靶区自动定位的方法因在整合成准三维图像的过程中由于内插误差原因造成成像不精确进而影响病灶的精确定位和治疗计划的准确性问题。The present invention provides a method for automatic positioning of patient target area in radiotherapy to solve the problem of inaccurate imaging caused by interpolation errors in the existing method of automatic positioning of patient target area in radiotherapy. Affects the precise location of the lesion and the accuracy of the treatment plan.

为了解决以上技术问题，本发明采取的技术方案是；In order to solve the above technical problems, the technical solution adopted by the present invention is;

一种放射治疗中病人靶区自动定位的方法，其特征在于，包括以下步骤：A method for automatically positioning a patient's target area in radiation therapy, comprising the following steps:

(1)输入图像数据；(1) Input image data;

(2)在治疗装置中设置可围绕病人同步旋转的光源和平板探测器；(2) A light source and a flat panel detector that can rotate synchronously around the patient are arranged in the treatment device;

(3)利用光源和平板探测器围绕病人靶区旋转扫描获得病人靶区的图像数据，记录相应的数据；(3) Use the light source and the flat panel detector to rotate and scan around the patient target area to obtain the image data of the patient target area, and record the corresponding data;

(4)对数据进行重建和处理，获得病人靶区的图像；(4) Reconstruct and process the data to obtain an image of the patient's target area;

(5)靶区的图像数据和输入的图像数据相比较，若两个图像位置不相符，执行步骤6，若两个图像相符，执行步骤7；(5) The image data of the target area is compared with the input image data, if the positions of the two images do not match, step 6 is performed, and if the two images match, step 7 is performed;

(6)根据两个图像比较的结果调整病人的位置，执行步骤2；(6) adjust the position of the patient according to the results of the comparison of the two images, and perform step 2;

(7)继续治疗。(7) Continue treatment.

所述步骤(3)中的数据包括：光源到探测器的距离A，背投影数据P，光源扫描轨迹的起点λ₁(和旋转支架的起始角θ₁对应)，光源扫描的终点λ₂(和旋转支架的终点位置的角度θ₂对应)，光源扫描轨迹起点时对应的扫描角θ₁，光源扫描终点时对应的扫描角θ₂。The data in the step (3) includes: the distance A from the light source to the detector, the back projection data P, the starting point λ ₁ of the light source scanning track (corresponding to the starting angle θ ₁ of the rotating bracket), the end point λ ₂ of the light source scanning (corresponding to the angle θ ₂ of the end position of the rotating bracket), the corresponding scanning angle θ ₁ when the light source scans the starting point of the track, and the corresponding scanning angle θ ₂ when the light source scans the end point.

所述步骤(4)对数据进行处理使用的是基于弦线段的重建算法，即当光源从位置1扫描到位置2时，光源的轨迹是弧线段

相应的弦线段λ₁λ₂所覆盖的物体部分的图像用如下公式重建：The step (4) uses a reconstruction algorithm based on chord segments to process the data, that is, when the light source scans from position 1 to position 2, the trajectory of the light source is an arc segment

The image of the part of the object covered by the corresponding chord segment λ ₁ λ ₂ is reconstructed with the following formula:

$f f (({x x}_{π π},, {λ λ}_{11},, {λ λ}_{22})) = = - - \frac{11}{22 π π} {&Integral; &Integral;}_{{λ λ}_{11}}^{{λ λ}_{22}} dλ dλ \frac{{A A}^{22} (({u u}_{d d},, {v v}_{d d}))}{{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |}^{22}} H h {{\frac{{P P}^{' '} (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{{A A}^{22} (({u u}_{d d}^{' '},, {v v}_{d d}^{' '}))}}}$

$- - \frac{11}{22 π π} {[[\frac{A A (({u u}_{d d},, {v v}_{d d}))}{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |} H h {{\frac{P P (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{A A (({u u}_{d d}^{' '},, {v v}_{d d}^{' '}))}}}]]}_{{λ λ}_{11}}^{{λ λ}_{11}}$

其中

和

分别是对和

的希尔波特变换，公式中

是对投影在弦线段

上的数据进行滤波，然后在整个λ₁λ₂范围内积分，f(x_π，λ₁，λ₂)是重建之后的物体图像内的灰度值分布。in

and

are right and

The Hilbert transform, in the formula

is the pair projected on the chord segment

Filter the data above, and then integrate in the entire range of λ ₁ λ ₂ , f(x _π , λ ₁ , λ ₂ ) is the gray value distribution in the reconstructed object image.

所述步骤(5)中，靶区的图像数据和输入的图像数据通过靶区的质心相比较，确定两个图像质心并获得相应的位置差值。In the step (5), the image data of the target area is compared with the input image data through the center of mass of the target area to determine the centroid of the two images and obtain the corresponding position difference.

所述步骤(6)中，通过控制系统，根据靶区的图像数据和输入的图像数据比较的差值，移动承载病人的治疗床，实现病人位置的调整。In the step (6), through the control system, according to the difference between the image data of the target area and the input image data, the treatment couch carrying the patient is moved to adjust the position of the patient.

在采用了上述技术方案后，采用基于平板探测器的真三维图像重建算法，真三维图像的空间分辨率是各向同性的，不需要进行内插，可以直接在三维空间实现对图像的处理，因此大大提高了成像的准确性和精度，解决了现有放射治疗中病人靶区自动定位时，因在整合成准三维图像的过程中由于内插误差原因造成成像不精确进而影响病灶的精确定位和治疗计划的准确执行的问题。After adopting the above-mentioned technical scheme, the true 3D image reconstruction algorithm based on the flat panel detector is adopted. The spatial resolution of the true 3D image is isotropic, no interpolation is required, and the image processing can be realized directly in the 3D space. Therefore, the accuracy and precision of imaging are greatly improved, and it solves the problem of inaccurate imaging caused by interpolation errors in the process of integrating quasi-three-dimensional images during the automatic positioning of patient target areas in existing radiotherapy, which affects the precise positioning of lesions. and the accurate execution of the treatment plan.

附图说明 Description of drawings

图1是本发明的放疗成像装置示意图；Fig. 1 is a schematic diagram of a radiotherapy imaging device of the present invention;

图2是虚拟PI线重建算法示意图；Figure 2 is a schematic diagram of a virtual PI line reconstruction algorithm;

图3是MLC叶片位置图；Figure 3 is a diagram of the position of the MLC blade;

图4是治疗过程靶区自动检测和定位流程图；Fig. 4 is a flow chart of automatic detection and positioning of the target area during the treatment process;

图5是治疗过程剂量实施反演和治疗计划自动修正流程图；Fig. 5 is a flow chart of dose inversion and treatment plan automatic correction in the treatment process;

图6是剂量反演算法定义的入射束注量平面的示意图；Fig. 6 is a schematic diagram of an incident beam fluence plane defined by a dose inversion algorithm;

图中1.光源，2.准直装置，3.人体，4.治疗床，5.探测器6.入射平面In the figure 1. Light source, 2. Collimation device, 3. Human body, 4. Treatment couch, 5. Detector 6. Incident plane

下面结合附图对本发明作进一步说明。The present invention will be further described below in conjunction with accompanying drawing.

具体实施方式 Detailed ways

如图1所示，用于放疗的过程成像的装置，包括：光源、准直装置、平板探测器和程控病人床等部件组成；其中，光源包括γ-光源和电子直线加速器产生的X-射线光源和其它用于放疗或者成像的辐射源，准直装置包括多叶光阑、准直器。在远距离立体定向放疗中，围绕病灶旋转的光源(LS)、程序控制的二维动态多叶光阑(2DMLC)和平板探测器(PD)，形成和远距离放疗装置集成在一起的影像导引适形调强放射治疗装置(IGIMRT：Imaging GuidedIntensity Modulated Radiotherapy)，当光源和探测器同步围绕治疗中心旋转时，其轨迹可以不在同一个平面内，旋转的环和垂直平面之间允许有一个倾角α，α角的大小，由放疗计划规定，选择的原则是尽可能避开人体内敏感的组织和敏感脏器。光源和探测器围绕治疗中心在同一α角旋转，也可以改变α角实现更加优化的源和探测器旋转轨迹。旋转的角度范围θ也可以根据实施放疗计划的最佳范围进行选择，可以在0到360度范围内任意选择。遵循放疗时尽可能地避开人体的敏感组织或者脏器、尽可能分散在正常组织中的剂量，尽可能缩短治疗时间，而又要满足靶区治疗剂量的原则，选择α和θ角。使用基于弦线段的重建算法，无论α和θ角是多少，都可以实现精确的图像重建。这里有三种可能的情况，第一种是当α角确定之后，在整个治疗过程中不再变化，实际上源和探测器仍然在圆环内运动，不过根据肿瘤在人体内的位置实现治疗区成像就可以了，这可以通过选择θ角(包括选择起始位置和扫描的结束位置)。As shown in Figure 1, the device used for radiotherapy process imaging includes: light source, collimation device, flat panel detector and program-controlled patient bed and other components; wherein, the light source includes X-rays produced by γ-light source and electron linear accelerator The light source and other radiation sources used for radiotherapy or imaging, and the collimation device includes a multi-leaf diaphragm and a collimator. In teletactic radiotherapy, the light source (LS) rotating around the lesion, the program-controlled two-dimensional dynamic multileaf diaphragm (2DMLC) and the flat panel detector (PD) form an image guide integrated with the teletherapy device. In IGIMRT (Imaging Guided Intensity Modulated Radiotherapy), when the light source and detector rotate around the treatment center synchronously, their trajectories may not be in the same plane, and an inclination angle is allowed between the rotating ring and the vertical plane α, the size of the α angle, is regulated by the radiotherapy plan, and the selection principle is to avoid sensitive tissues and sensitive organs in the human body as much as possible. The light source and detector rotate around the treatment center at the same α angle, and the α angle can also be changed to achieve a more optimized source and detector rotation trajectory. The rotation angle range θ can also be selected according to the optimal range for implementing the radiotherapy plan, and can be arbitrarily selected within the range of 0 to 360 degrees. According to the principle of avoiding sensitive tissues or organs of the human body as much as possible during radiotherapy, dispersing the dose in normal tissues as much as possible, shortening the treatment time as much as possible, and satisfying the principle of treatment dose in the target area, the α and θ angles are selected. Using the chord-segment-based reconstruction algorithm, accurate image reconstruction can be achieved regardless of the α and θ angles. There are three possible situations here. The first one is that after the α angle is determined, it will not change during the whole treatment process. In fact, the source and detector are still moving in the circle, but the treatment area is realized according to the position of the tumor in the human body. Imaging is done, which can be done by selecting the angle theta (including selecting the start position and the end position of the scan).

如图2所示，当光源λ从λ₁点扫描到λ₂点时，光源的轨迹是弧线段

相应的弦线段λ₁λ₂所覆盖的物体部分的图像都能重建出来，而直线段λ₁λ₂重建所用的几何结构，重建算法：As shown in Figure 2, when the light source λ scans from λ ₁ point to λ ₂ point, the trajectory of the light source is an arc segment

The images of the part of the object covered by the corresponding chord segment λ ₁ λ ₂ can be reconstructed, and the geometric structure used for the reconstruction of the straight line segment λ ₁ λ ₂ , the reconstruction algorithm:

$f f (({x x}_{κ κ},, {λ λ}_{11},, {λ λ}_{22})) = = - - \frac{11}{22 π π} {&Integral; &Integral;}_{{λ λ}_{11}}^{{λ λ}_{22}} dλ dλ \frac{{A A}^{22} (({u u}_{d d},, {v v}_{d d}))}{{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |}^{22}} H h {{\frac{{P P}^{' '} (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{{A A}^{22} (({u u}_{d d}^{' '},, {v v}_{d d}^{' '}))}}}$

$- - \frac{11}{22 π π} {[[\frac{A A (({u u}_{d d},, {v v}_{d d}))}{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |} H h {{\frac{P P (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{A A (({u u}_{d d}^{' '},, {v v}_{d d}^{' '}))}}}]]}_{{λ λ}_{22}}^{{λ λ}_{11}}$

其中

和

分别是对

和

的希尔波特变换。式中A是光源到探测器的距离，P是背投影数据，公式(1)等式左边的第一式

是对投影在弦线段

上的数据进行滤波，然后在整个λ₁λ₂范围内积分。in

and

are right

and

Hilbert transform of . In the formula, A is the distance from the light source to the detector, P is the back projection data, and the first formula on the left side of formula (1)

is the pair projected on the chord segment

Filter the data on , and then integrate over the entire λ ₁ λ ₂ range.

这里的f(x_π，λ₁，λ₂)是重建之后的物体图像内的灰度值分布， $x_{κ} = \overset{&OverBar;}{x_{κ_{1}} x_{κ_{2}}},$ 是弦线段的长度，其端点分别为

和

λ₁是光源扫描轨迹的起点，它对应的扫描角为θ₁，λ₂光源扫描的终点，对应的扫描角为θ₂。因此，θ＝|θ₁-θ₂|。公式(1)是普适的滤波背投影公式。已经证明，当光源从λ₁点扫描到λ₂点时，弦线段可以完全充满被成像的整体物体，而这个体积不必是封闭的区域，能够满足对患者局部成像需要。Here f(x _π , λ ₁ , λ ₂ ) is the gray value distribution in the reconstructed object image,

x_{κ} = \overset{&OverBar;}{x_{κ_{1}} x_{κ_{2}}},

is the length of the chord segment whose endpoints are respectively

and

λ ₁ is the starting point of the light source scanning trajectory, and its corresponding scanning angle is θ ₁ , and the end point of λ ₂ light source scanning, corresponding to the scanning angle θ ₂ . Therefore, θ=|θ ₁ -θ ₂ |. Equation (1) is a universal filtered backprojection equation. It has been proved that when the light source is scanned from point λ ₁ to point λ ₂ , the chord segment can completely fill the whole object to be imaged, and this volume does not have to be a closed area, which can meet the needs of local imaging of patients.

如图3所示，2D多叶光阑(MLC)在某一个角度θ上的形状由光源和病灶外轮廓线(例如以临床靶区：CTV的外轮廓线为准)相切的包络线在2DMLC上切成的形状来定义。这个形状是在放疗前，由该病人的放射治疗计划规定的。因此，2D多叶光阑(MLC)的控制程序在放疗计划执行过程中，按照诊断时患者图像和放疗计划对MLC叶片的定位要求，满足在这个位置上从束流方向(BEV)看过去的肿瘤形状适配。而2DMLC构成的形状和在这个方向上放疗计划定义的治疗靶区(PTV)形状完全一致。随着θ角度的变化，2DMLC将按照上述方法通过叶片的运动构成和该角度上肿瘤治疗靶区适配的形状，这是控制叶片运动的程序根据放疗计划参数设定的。As shown in Figure 3, the shape of the 2D multileaf diaphragm (MLC) at a certain angle θ is the envelope that is tangent to the light source and the outer contour of the lesion (for example, based on the outer contour of the clinical target area: CTV) Shape cut on 2DMLC to define. This shape is prescribed by the patient's radiation treatment plan prior to radiation therapy. Therefore, the control program of the 2D multi-leaf diaphragm (MLC) meets the requirements of the positioning of the MLC blades in accordance with the patient image and the radiotherapy plan at the time of diagnosis during the execution of the radiotherapy plan, and satisfies the position viewed from the beam direction (BEV) at this position. Tumor shape fit. The shape of the 2DMLC is completely consistent with the shape of the treatment target volume (PTV) defined by the radiotherapy plan in this direction. As the θ angle changes, the 2DMLC will form a shape adapted to the tumor treatment target volume at this angle through the movement of the blades according to the above method, which is set according to the parameters of the radiotherapy plan by the program that controls the motion of the blades.

如图4所示，一种放射治疗中病人靶区自动定位的方法，包括以下步骤：As shown in Figure 4, a method for automatically positioning a patient's target area in radiotherapy, comprising the following steps:

(1)输入图像数据；(1) Input image data;

(7)继续治疗。(7) Continue treatment.

步骤(5)中，靶区的图像数据和输入的图像数据通过靶区的质心相比较，确定两个图像质心并获得相应的位置差值。In step (5), the image data of the target area is compared with the input image data through the centroid of the target area, and the two image centroids are determined and corresponding position differences are obtained.

步骤(6)中，根据靶区的图像数据和输入的图像数据比较的差值，通过控制系统，移动承载病人的治疗床，实现病人位置的调整。In step (6), according to the difference between the image data of the target area and the input image data, the treatment bed carrying the patient is moved through the control system to adjust the position of the patient.

如图5所示，本发明实施过程中病人靶区剂量反演的方法，包括以下步骤：As shown in Figure 5, the method for inversion of the dose of the patient's target area during the implementation of the present invention includes the following steps:

(1)输入图像数据；(1) Input image data;

(3)利用光源和平板探测器围绕病人靶区旋转扫描获得病人靶区图像的数据和透过病人靶区的剂量数据，记录相应的数据；(3) Use the light source and the flat panel detector to rotate and scan around the patient target area to obtain the image data of the patient target area and the dose data through the patient target area, and record the corresponding data;

(4)对病人靶区图像的数据进行重建和处理，根据处理结果调整病人的位置数据；(4) Reconstruct and process the data of the patient's target area image, and adjust the patient's position data according to the processing result;

(5)对透过病人靶区的剂量数据进行处理，获得病人靶区接受的剂量分布数据；(5) Process the dose data passing through the patient's target area to obtain the dose distribution data received by the patient's target area;

(6)靶区接受的剂量分布数据和输入的剂量分布数据相比较，若两个数据不相符，执行步骤7，若两个数据相符，执行步骤8；(6) Compare the dose distribution data received by the target area with the input dose distribution data, if the two data are not consistent, perform step 7, and if the two data are consistent, perform step 8;

(7)根据两个剂量分布数据比较的结果调整输入数据；(7) Adjust the input data according to the results of the comparison of the two dose distribution data;

(8)继续治疗。(8) Continue treatment.

步骤(4)中，靶区的图像数据和输入的图像数据通过靶区的质心相比较，确定两个图像质心并获得相应的位置差值，根据该位置差值，调整病人的位置数据，通过控制系统，移动承载病人的治疗床，实现病人位置的调整。In step (4), the image data of the target area is compared with the input image data through the centroid of the target area to determine the two image centroids and obtain the corresponding position difference. According to the position difference, the patient's position data is adjusted. The control system moves the treatment bed carrying the patient to realize the adjustment of the patient's position.

步骤(6)中，病人靶区接受的剂量数据和输入的剂量数据相比较，确定两个剂量分布的差值是否满足要求，根据剂量分布的差值，通过控制系统，改变2D多叶光阑的形状，实现靶区接受的剂量的调整。In step (6), the dose data received by the patient's target area is compared with the input dose data to determine whether the difference between the two dose distributions meets the requirements. According to the difference between the dose distributions, the 2D multi-leaf aperture is changed through the control system The shape can realize the adjustment of the dose received by the target area.

按照质量控制的要求，在放疗机执行放疗计划前，要用体模检查放疗计划是否正确，这个步骤是通过照射体模，并和放疗计划在照射体模相同的条件下计算出来的结果进行比较，如果误差在允许的误差范围内，说明放疗计划是可行的，否则就要修改放疗计划直到满足要求为止，这属于通常放疗计划验证的过程；在正式影像导引的放疗中，首先要按照放射治疗中病人靶区自动定位的方法，对病人进行定位，直到把病人移到治疗等中心位置，这个过程在整个放疗过程中要动态地实现，但是纠正位置偏差的运动，是小范围内的运动。According to the requirements of quality control, before the radiotherapy machine executes the radiotherapy plan, it is necessary to use the phantom to check whether the radiotherapy plan is correct. This step is to compare the results calculated by irradiating the phantom with the radiotherapy plan under the same conditions. , if the error is within the allowable error range, it means that the radiotherapy plan is feasible, otherwise the radiotherapy plan must be modified until it meets the requirements. This is the usual verification process of the radiotherapy plan; The method of automatic positioning of the patient's target area during treatment is to position the patient until the patient is moved to the isocenter position of the treatment. This process must be dynamically realized during the entire radiotherapy process, but the movement to correct the position deviation is a movement within a small range .

在实际治疗过程，实时纠正位置偏差需要时间，因为在整个治疗过程中，执行命令的过程是分成时间段的，在一个时间段内，治疗机和靶区位置虽然都在运动，但是运动量不会很大。虽然通过病人床的运动可以动态适配放疗计划要求的剂量场分布，但是由于执行命令需要时间，这个过程仍然有可能造成实际执行的剂量场分布和计划确定的剂量场分布之间的偏差，这个偏差通过控制多叶光阑准直器或者控制治疗机的治疗时间等技术措施进行补偿校正，这是需要输入新的位置偏差数据(Δx，Δy，Δz)，通过基于多叶光阑的剂量计算，针对重置后的MLC分布补偿该剂量场分布偏差。In the actual treatment process, it takes time to correct the position deviation in real time, because during the entire treatment process, the process of executing commands is divided into time periods. In a time period, although the treatment machine and the position of the target area are moving, the amount of movement will not very big. Although the dose field distribution required by the radiotherapy plan can be dynamically adapted through the movement of the patient bed, because it takes time to execute the order, this process may still cause a deviation between the actually executed dose field distribution and the dose field distribution determined by the plan. The deviation is compensated and corrected by technical measures such as controlling the multi-leaf aperture collimator or controlling the treatment time of the treatment machine, which requires input of new position deviation data (Δx, Δy, Δz), through the dose calculation based on the multi-leaf aperture , to compensate for this dose field distribution deviation for the reset MLC distribution.

剂量反演过程，是通过剂量反演算法计算出剂量偏差，根据偏差调整MLC位置的变动，通过控制台使得动态多叶光阑的位置得到修正。The dose inversion process is to calculate the dose deviation through the dose inversion algorithm, adjust the change of the MLC position according to the deviation, and correct the position of the dynamic multi-leaf diaphragm through the console.

平板探测器上以象素为单位记录的、经过与人体相互作用之后的X-射线信息，既用于作为病人进入治疗床后的定位信息，也用于确定由于病人生理运动带动的治疗中心位置的偏差信息，并在反演病人体内的剂量分布的同时，校正由于治疗靶区运动引起的剂量分布校正信息。The X-ray information recorded in pixels on the flat panel detector after interacting with the human body is used not only as the positioning information of the patient after entering the treatment bed, but also used to determine the position of the treatment center driven by the patient's physiological movement The deviation information of the patient, and at the same time of inverting the dose distribution in the patient, corrects the dose distribution correction information caused by the movement of the treatment target area.

上述流程中，凡是位置信息都是通过普适图像重建公式(1)的计算获得真三维图像，通过计算获得肿瘤的质心位置坐标，通过图像的分割获得肿瘤的治疗区域信息，然后通过对治疗系统控制台对病人床的参数的设定实现自动摆位和定位；而所有由于位置偏差引起的剂量分布与治疗计划的剂量分布之间的偏差都是由于放疗计划靶区和实际执行的治疗靶区之间在形状上的失配造成的，在算出位置偏差后，通过改变放疗机和多叶光阑(MLC)的控制参数达到实时校正的目标。无论定位的信息还是剂量校正的信息都是在基于体素的真三维空间实现的，存在数据量大，运算复杂，需要有功能强大的计算机系统实现实施计算和显示。In the above process, all position information is obtained through the calculation of the universal image reconstruction formula (1) to obtain a true three-dimensional image, the centroid position coordinates of the tumor are obtained through calculation, the treatment area information of the tumor is obtained through image segmentation, and then the treatment system The console sets the parameters of the patient bed to realize automatic positioning and positioning; and all deviations between the dose distribution caused by position deviation and the dose distribution of the treatment plan are due to the target area of the radiotherapy plan and the actual treatment target area It is caused by the mismatch in shape between them. After calculating the position deviation, the goal of real-time correction is achieved by changing the control parameters of the radiotherapy machine and the multi-leaf aperture (MLC). Both the positioning information and the dose correction information are realized in the true three-dimensional space based on voxels. There is a large amount of data and complex calculations, and a powerful computer system is required to implement the calculation and display.

利用成像获得的信息，首先实现对病人的自动摆位和治疗过程对治疗靶区位置移动进行监测和自动移位，因此造成的剂量误差通过剂量反演进行补偿。Using the information obtained by imaging, firstly realize the automatic positioning of the patient and the monitoring and automatic displacement of the position movement of the treatment target area during the treatment process, so that the dose error caused by it is compensated through dose inversion.

作为病人治疗靶区位置的实时定位信息，可以通过局部感兴趣区快速成像技术的实现，即由于公式(1)可以在任意θ角度范围内成像，只要这个角度范围所对的弦能够覆盖肿瘤区域就可以。其方法是在根据肿瘤的位置首先确定θ角的起始值θ₁，然后根据完全覆盖肿瘤区域的要求，确定扫描的角度范围，确定扫描终止的θ₂角，通过公式(1)的重建算法，获得的相应的图像，通过图像处理技术获得肿瘤的质量中心和外轮廓线。以肿瘤靶区质心的运动作为治疗中心位置偏移量(Δx，Δy，Δz)，而把患者的治疗中心移到Δx＝Δy＝，Δz＝0的位置。因此，位置偏移量是在三维空间定义的，在放疗过程中，这组数据始终受到监测，从而给出肿瘤靶区中心在整个治疗过程中的运动方向、运动速度和绝对位置偏移量(Δx_{i，j，k，t}，Δy_{i，j，k，t}，Δz_{i，j，k，t})，这里的脚标表示在位置(i，j，k)的位置上，在时刻t的位移量数组。位置的监测是在通常的照笛卡儿坐标系(X，Y，Z)中定义的，和医学成像中惯用的方法一致。As the real-time positioning information of the position of the patient's treatment target area, it can be realized by the rapid imaging technology of the local interest area, that is, since the formula (1) can be imaged in any θ angle range, as long as the chord to which this angle range corresponds can cover the tumor area can. The method is to first determine the initial value θ ₁ of the θ angle according to the position of the tumor, and then determine the scanning angle range according to the requirement of completely covering the tumor area, and determine the θ ₂ angle at which the scanning ends, and then use the reconstruction algorithm of formula (1) , the corresponding image is obtained, and the center of mass and outer contour of the tumor are obtained by image processing technology. The movement of the centroid of the tumor target area is used as the position offset of the treatment center (Δx, Δy, Δz), and the patient’s treatment center is moved to the position of Δx=Δy=, Δz=0. Therefore, the position offset is defined in three-dimensional space, and this set of data is always monitored during radiotherapy, thus giving the movement direction, movement speed and absolute position offset of the center of the tumor target area during the whole treatment process ( Δx _{i, j, k, t} , Δy _{i, j, k, t} , Δz _{i, j, k, t} ), where the subscript indicates that at the position (i, j, k), at time t Array of offsets. The monitoring of the position is defined in the usual Cartesian coordinate system (X, Y, Z), consistent with the usual methods in medical imaging.

本发明对放疗计划定义基于体素的剂量场反演算法，对由于靶区运动造成的剂量分布的偏差进行实时补偿。补偿的含义是获得以体素为单位的新的剂量场分布，这个剂量场分布已经包含了校正差值剂量之后的结果。方法是根据新的剂量场分布要求，通过放疗计划系统的计算，变成控制治疗机和2DMLC有关叶片的运动的控制参数，通过新参数的设定和放疗计划实时计算出新的治疗计划或者通过对原来治疗计划的修正变成满足治疗机当前位置的放疗计划，因此放疗机的送束参数和2DMLC有关叶片的运动的控制参数都将被重新更新。这个过程虽然在动态中实现的，直到整个的治疗过程完成，但是根据数据更新的速度需要设定一个时间T，作为更新参数的周期，T的取值要根据具体放疗计划系统的能力，计算机剂量计算的速度等因素来决定。为了加快计算速度，需要对病人生理运动引起的靶区运动规律建模，例如对呼吸和心跳等有规律的生理参数进行估计，估计它们的运动对靶区治疗中心位置的影响。可以通过与放疗前经过优化过并输入到治疗机内的最初放疗计划中规定的治疗中心位置数据的比较，获得模型参数的定量数据。通过这些数据获得控制治疗机的治疗头的运动参数和2DMLC叶片运动的输入数据组的过程和开始执行放疗计划的设置方法相同。这组数据也用于病人体内剂量的反演计算。The invention defines a voxel-based dose field inversion algorithm for the radiotherapy plan, and performs real-time compensation for the deviation of the dose distribution caused by the movement of the target area. The meaning of compensation is to obtain a new dose field distribution in units of voxels, and this dose field distribution already includes the result after correcting the difference dose. The method is based on the new dose field distribution requirements, through the calculation of the radiotherapy planning system, it becomes the control parameters for controlling the movement of the treatment machine and 2DMLC blades, and the new treatment plan is calculated in real time through the setting of new parameters and the radiotherapy plan or through The modification of the original treatment plan becomes the radiotherapy plan that satisfies the current position of the treatment machine, so the beam delivery parameters of the radiotherapy machine and the control parameters related to the movement of the blades of the 2DMLC will be updated again. Although this process is implemented dynamically until the entire treatment process is completed, a time T needs to be set according to the data update speed as the cycle of updating parameters. The value of T depends on the capability of the specific radiotherapy planning system and the computer dose. calculation speed and other factors to determine. In order to speed up the calculation, it is necessary to model the movement of the target area caused by the patient's physiological movement, such as estimating regular physiological parameters such as breathing and heartbeat, and estimating the impact of their movement on the position of the treatment center of the target area. Quantitative data of the model parameters can be obtained by comparison with the treatment center location data specified in the initial radiation therapy plan optimized before radiation therapy and input into the treatment machine. The process of obtaining the motion parameters of the treatment head of the treatment machine and the input data set of the 2DMLC blade movement through these data is the same as the setting method of starting to execute the radiotherapy plan. This set of data is also used in the inverse calculation of the patient's internal dose.

如图6所示，对剂量反演算法，本发明将用探测器上采集到的数据，以及事先存贮在计算机内的用蒙特卡罗(Monte Carlo)方法计算获得的探测器响应函数得到在与靠近治疗源一侧的与治疗锥束中心轴垂直的平面上(定义为入射平面IP：Incident Plane)的入射束的能量注量分布。这个IP平面是为了计算需要设定的一个虚拟平面，IP平面上像素的大小，要根据剂量反演精度和计算机计算速度的可能性加以选择。剂量反演的目的是要获得IP平面上以象素为单位的入射束的数据Ψ_ij(E_i，j，Φ_i，j)，这里的E_i，j为入射束在位置(i，j)处的能谱，Φ_i，j(E_i，j)为同一位置上的注量，Φ_i，j可以设定为入射束的平均注量，也可以设定为某一能量间隔内射线的注量。其中脚标(i，j)表示象素所在的位置坐标。我们的任务就是根据放疗机辐射源的情况，以及探测器测量的剂量数据D_d(m，n)(用探测器上测量到的、经过刻度过的灰度值表示，这里的脚标(m n)表示的是探测器平面上的象素位置坐标，最后通过确定IP平面上Ψ_ij(E_i，j，Φ_i，j)在探测器平面的每个象素剂量D_d(m，n)的贡献权重w_ij，完全确定Ψ_ij(E_i，j，Φ_i，j)的值，由下列公式进行计算：As shown in Figure 6, for the dose inversion algorithm, the present invention will use the data collected on the detector and the detector response function stored in the computer in advance to calculate and obtain by Monte Carlo method The energy fluence distribution of the incident beam on the plane near the treatment source and perpendicular to the central axis of the treatment cone beam (defined as the incident plane IP: Incident Plane). This IP plane is a virtual plane that needs to be set for calculation, and the size of pixels on the IP plane should be selected according to the possibility of dose inversion accuracy and computer calculation speed. The purpose of dose inversion is to obtain the data Ψ _ij (E _{i, j} , Φ _{i, j} ) of the incident beam on the IP plane in units of pixels, where E _{i, j} is the incident beam at the position (i, j ), Φ _{i, j} (E _{i, j} ) is the fluence at the same position, Φ _{i, j} can be set as the average fluence of the incident beam, or as the ray within a certain energy interval of injection. The subscripts (i, j) represent the position coordinates of the pixel. Our task is based on the radiation source of the radiotherapy machine and the dose data D _d (m, n) measured by the detector (expressed by the scaled gray value measured on the detector, the subscript (m n ) represents the pixel position coordinates on the detector plane, and finally by determining the dose D _d (m, n) of each pixel on the detector plane Ψ _ij (E _{i, j} , Φ _{i, j} ) on the IP plane The contribution weight w _ij of , completely determines the value of Ψ _ij (E _{i, j} , Φ _{i, j} ), which is calculated by the following formula:

${D D.}_{d d} ((m m,, n no)) = = \underset{i i,, j j}{Σ Σ} {w w}_{i i,, j j} \cdot \cdot {Λ Λ}_{ij ij}^{mn mn} (({E E.}_{i i,, j j},, {Φ Φ}_{i i,, j j})) - - - - - - ((22))$

这里的w_i，j脚标(i，j)和Ψ_ij(E_i，j，Φ_i，j)的脚标(i，j)取值完全一致，Λ_ij ^mn(E_i，j，Φ_i，j)为入射平面IP上位置(i，j)处单位注量入射束在探测器探测单元(m，n)上的响应。The w _{i, j} subscript (i, j) and the subscript (i, j) of Ψ _ij (E _{i, j} , Φ _{i, j} ) have exactly the same value, and Λ _ij ^mn (E _{i, j} , Φ _{i, j} ) is the response of the unit fluence incident beam on the detector unit (m, n) at the position (i, j) on the incident plane IP.

一旦我们知道Ψ_ij(E_i，j，Φ_i，j)值之后，就可以通过这些虚拟光源的数据，采用已经成熟的任何一种正向放射剂量的计算方法获得患者体内的剂量分布。为了获得Ψ_ij值，我们用蒙德卡罗(Monte Carlo)方法，事先把入射辐射源能谱覆盖的能量范围内各种能量的入射线在人体内的等效辐射程ER(E(i，j))和相应入射线与人体靠近探测器一侧的外表面的交点到探测器的距离D_r计算出来，构成ER-D_r配对的查找数组表，事先存在计算机内。为了保证方法的通用性，我们需要把ER(E(i，j))转化成水的等效长度，使用下面的公式：Once we know the value of Ψ _ij (E _{i, j} , Φ _{i, j} ), we can use the data of these virtual light sources to obtain the dose distribution in the patient's body by using any mature calculation method of forward radiation dose. In order to obtain the value of _Ψij , we use the Monte Carlo method to calculate the equivalent radiation range ER(E(i, j)) and the distance D _r from the intersection of the corresponding incident ray and the outer surface of the human body close to the detector to the detector is calculated to form a lookup array table of ER-D _r pairing, which is stored in the computer in advance. In order to ensure the generality of the method, we need to convert ER(E(i, j)) into the equivalent length of water, using the following formula:

ER(E(i，j))＝ρ₁×L₁+ρ₂×L₂+…+ρ_k×L_k (3)ER(E(i,j))=ρ ₁ ×L ₁ +ρ ₂ ×L ₂ +…+ρ _k ×L _k (3)

这里的ρ₁，ρ₂，…，ρ_k为某一个粒子(或者某一束射线)穿过人体后被探测器记录的过程中经过的人体内的物质时，根据电子密度不同划分的物质单元的相对于水的电子密度值，L₁，L₂，…，L_k为该物质单元在射线方向上的长度。公式(3)把射线经过的路径上不同密度的物质都转化为等效水的长度，以方便计算和比较。因为事先计算出来存贮在计算机内的ER-D_r数据查找表中数据量总是有限的，实际使用时还需要对ER-D_r进行内插。事先计算存贮在计算机内的ER和D_r的长度，可以通过人体组织计算计算出来的实际长度是不一致的，采用一般的线性内插就可以获得需要的值。Here ρ ₁ , ρ ₂ ,..., ρ _k are the material units divided according to the different electron densities when a certain particle (or a certain beam of rays) passes through the human body and is recorded by the detector. The electron density value of relative to water, L ₁ , L ₂ ,..., L _k is the length of the material unit in the ray direction. The formula (3) converts the substances of different densities on the path of the ray into the length of equivalent water to facilitate calculation and comparison. Because the amount of data in the ER-D _r data look-up table calculated in advance and stored in the computer is always limited, it is necessary to interpolate the ER-D _r in actual use. The lengths of ER and D _r stored in the computer are calculated in advance, and the actual lengths calculated through human tissue calculations are inconsistent, and the required values can be obtained by general linear interpolation.

上述剂量反演并获得基于体素的剂量差值分布的过程，在整个治疗过程中被分割成合理的时间间隔T(T的选择要根据治疗计划完成肿瘤治疗的需要以及计算机的计算速度来确定)的周期内完成。根据T的大小可以定义是否达到实时剂量的情况进行控制。如果放疗机及其配置的计算机系统还达不到实时计算的水平时，也可以通过停止在某个角度上进行照射和计算，获得修正量后再进行旋转照射的步进方式来实现，但是在每个角度上等待的时间应该是患者能够承受的。新剂量分布的改进，是通过对治疗机旋转角度(θ和α角的选择)、旋转速度V、2DMLC中有关叶片的运动轨迹和运动速度的改变实现的。这些数据组构成治疗机运动控制的数组。上述过程，就是基于平板探测器动态四维成像为基础的影像导引的适形调强放疗(IGCIMRT)。这种放疗方法具有实形、实时逆向优化放疗剂量场分布的功能并改善治疗精度。The above-mentioned process of dose inversion and obtaining voxel-based dose difference distribution is divided into reasonable time intervals T during the entire treatment process (the selection of T should be determined according to the needs of the treatment plan to complete the tumor treatment and the calculation speed of the computer ) cycle is completed. According to the size of T, it can be defined whether the real-time dose is reached for control. If the radiotherapy machine and its configured computer system are not up to the level of real-time calculation, it can also be realized by stopping the irradiation and calculation at a certain angle, and then performing rotation irradiation after obtaining the correction amount. The waiting time for each angle should be bearable by the patient. The improvement of the new dose distribution is realized by changing the rotation angle (the selection of θ and α angle) of the treatment machine, the rotation speed V, the motion track and the motion speed of the relevant blades in the 2DMLC. These data records form an array for the motion control of the treatment machine. The above process is image-guided intensity-modulated radiation therapy (IGCIMRT) based on dynamic four-dimensional imaging of flat panel detectors. This radiotherapy method has the function of real-time reverse optimization of radiotherapy dose field distribution and improves treatment accuracy.

本发明在图像重建方面，无论是患者在治疗床上的自动摆位，还是通过对治疗过程的实时成像，以及通过图像处理获得的治疗中心位置和肿瘤外轮廓线的数据，实现对病人位置的自动校正和监测，从而实现对运动靶区的自动跟踪以及对靶区运动造成的剂量分布的劣化进行校正。图像重建算法方面，我们采用基于弦线段的真三维重建快速算法，该算法和传统的断层图像重建的算法不同，可以实现对局部感兴趣区的动态四维成像。In terms of image reconstruction, whether it is the automatic positioning of the patient on the treatment bed, or the real-time imaging of the treatment process, as well as the data of the treatment center position and tumor outline obtained through image processing, the automatic positioning of the patient's position can be realized. Correction and monitoring, so as to realize the automatic tracking of the moving target area and the correction of the deterioration of the dose distribution caused by the movement of the target area. In terms of image reconstruction algorithms, we use a fast true 3D reconstruction algorithm based on string segments, which is different from traditional tomographic image reconstruction algorithms, and can realize dynamic 4D imaging of local regions of interest.

在实施IGCIMRT时，虽然整个靶区在实施治疗的过程中，由于人体的生理运动和患者的不由自主的运动，可能会发生运动，但是对大多数实体肿瘤来说，我们认为由治疗中心和肿瘤外轮廓线定义的肿瘤内部物质之间不发生相对运动。而对肿瘤物质内部发生相对运动的肿瘤，例如淋巴癌和血癌，则采用实形避免放疗(CART：Conform Avoiding Radiotherapy)。这里的适形是对治疗靶区而言(PTV)，即整个多叶光阑定义的区域应该是计划靶区PTV，在PTV内如果存在敏感组织，需要通过设置MLC的的位置把它们保护起来，这种放疗过程称为实形避免放疗。During the implementation of IGCIMRT, although the entire target area may move due to the physiological movement of the human body and the involuntary movement of the patient during the treatment process, for most solid tumors, we believe that the treatment center and outside the tumor No relative motion occurs between the tumor interior material defined by the contour lines. For tumors with relative movement inside the tumor material, such as lymphoma and blood cancer, Conform Avoiding Radiotherapy (CART: Conform Avoiding Radiotherapy) is used. The conformity here is for the treatment target volume (PTV), that is, the area defined by the entire multi-leaf aperture should be the planned target volume PTV. If there are sensitive tissues in the PTV, they need to be protected by setting the position of the MLC. , This radiotherapy process is called solid avoidance radiotherapy.

本发明还根据放疗时光源的位置、治疗靶区的三维空间位置和成像区域的大小，发展出一种和治疗肿瘤靶区相匹配的局部肿瘤剂量反演算法，这种算法适用于远距离肿瘤放疗的各种装置，可以大大节省剂量计算的时间，满足实时剂量反演的需要。According to the position of the light source during radiotherapy, the three-dimensional space position of the treatment target area and the size of the imaging area, the present invention develops a local tumor dose inversion algorithm that matches the treatment tumor target area. This algorithm is suitable for distant tumors. Various devices for radiotherapy can greatly save the time for dose calculation and meet the needs of real-time dose inversion.

本发明的第一实施例，⁶⁰Co立体定向放疗机装上平板探测器之后可以作为上述思想的一个实施例。因为⁶⁰Coγ-源是单能的，所以在能量注量平面上只考虑注量分布就可以了，这时Ψ_ij(E_i，j，Φ_i，j)＝Ψ_ij(Φ_i，j)。但是，只有辐射源旋转的⁶⁰Co立体定向放疗机才能使用本专利提供的方法。这对中国公司生产的多个⁶⁰Co或者单个旋转的⁶⁰Co立体定向放疗机都适用。这时需要增加一个专门用于对病人摆位的成像源，减少成像源γ-射线的能量，可以提高对软组织成像的对比度，本专利的提供的公式1，可以实现对病人的自动摆位图像的重建，通过重建后对图像的分割，确定治疗中心和外轮廓线的方法则完全相同。获得肿瘤新的治疗中心的位置之后，通过控制台把病人自动移送到治疗中心的过程是对病人的自动摆位。In the first embodiment of the present invention, ^{a 60} Co stereotactic radiotherapy machine equipped with a flat-panel detector can be used as an embodiment of the above idea. Because the ⁶⁰ Coγ-source is monoenergetic, it is enough to only consider the fluence distribution on the energy fluence plane, then Ψ _ij (E _{i, j} , Φ _{i, j} ) = Ψ _ij (Φ _{i, j} ) . However, only the ⁶⁰ Co stereotactic radiotherapy machine with rotating radiation source can use the method provided by this patent. This is applicable to multiple ⁶⁰ Co or single rotating ⁶⁰ Co stereotactic radiotherapy machines produced by Chinese companies. At this time, it is necessary to add an imaging source specially used for positioning the patient, and reduce the energy of the γ-ray of the imaging source, which can improve the contrast of soft tissue imaging. The formula 1 provided by this patent can realize the automatic positioning image of the patient The method of determining the treatment center and the outer contour is exactly the same through the segmentation of the image after reconstruction. After obtaining the location of the new tumor treatment center, the process of automatically moving the patient to the treatment center through the console is the automatic positioning of the patient.

而本专利描述的对病人体内剂量的反演算法，完全适用于单源或者多源的⁶⁰Co立体定向放疗机的情况。However, the inversion algorithm for the patient's internal dose described in this patent is fully applicable to the case of single-source or multi-source ⁶⁰ Co stereotactic radiotherapy machines.

本发明的第二实施例，电子直线加速器放疗机上装上平板探测器之后达到上述目的的描述。这里也可以采用一个自动定位γ-射线源的方式，实现对病人的自动定位，γ-射线源的能量选择在150keV以下更好，这个源可以固定在加速器治疗头射线束的出口处，完全模拟电子直线加速器出束时的情况。The second embodiment of the present invention is a description of achieving the above purpose after installing a flat panel detector on the electron linear accelerator radiotherapy machine. An automatic positioning of the γ-ray source can also be used here to realize the automatic positioning of the patient. It is better to choose the energy of the γ-ray source below 150keV. This source can be fixed at the exit of the beam of the accelerator treatment head, completely simulating The condition of the electron linear accelerator when it exits the beam.

本发明也完全适用于医用电子直线加速器放疗期间实时成像系统用于监测病人脏器的运动，并实现实时校正的方法。也适合通过对病人靶区四维动态成像获得的数据，实现对运动靶区的自动跟踪和定位、根据治疗位置的变化调整治疗机的控制参数，满足变化后剂量场的要求，通过很好的临床流程设计，把整个过程设计为流畅的操作过程度。The present invention is also fully applicable to the method that the real-time imaging system is used to monitor the movement of the patient's organs during the radiotherapy of the medical electron linear accelerator and realize real-time correction. It is also suitable for the data obtained by four-dimensional dynamic imaging of the patient's target area to realize automatic tracking and positioning of the moving target area, adjust the control parameters of the treatment machine according to changes in the treatment position, and meet the requirements of the changed dose field. Process design, design the whole process as a smooth operation process.

实现该系统相应功能中采用了一系列先进技术：1.根据临床实施的可能性，经过准直的光源、探测器围绕病人治疗靶区在不同的角度范围内采集数据，数据采集过程可以在有限角度和有限床进旋速比数值范围内实现，通过弦线真三维重建算法对患者靶区各向同性分辨率的真三维成像(VCT)。2.通过限制光源的尺寸和选择合理的平板探测器象元大小，保证用真三维体成像数据实现的对病人靶区的空间定位好于断层放疗的定位精度；3.基于VCT成像的数据，通过图像分割和质心的计算，获得病人治疗中心的位置坐标(治疗中心可以不止一个，以医生的处方为准)，通过程序控制的治疗床的运动，自动实现对患者的摆位，在靶区在治疗期间运动的情况，动态跟踪靶区的运动，实现对靶区运动的建模，以及补偿由于靶区运动造成的对剂量场分布的劣化，实时动态地保证放疗的精度。对于多个治疗中心的情况，则根据事先确定的顺序，分别实现对病灶位置的自动跟踪，以及根据动态优化的剂量场分布调整治疗机的参数，满足优化后剂量场分布的要求；4.根据束流的特点和治疗靶区的形状，对辐射光源进行建模，用蒙德卡罗方法计算光源的核函数，通过与探测器动态旋转过程中采集数据为依据，实现对治疗剂量的反演；5.通过剂量反演过程中形成的三维剂量场分布数据与治疗计划三维剂量场分布之间的比较，实现治疗过程对治疗机参数的控制，实时地实现对治疗过程优化，满足对运动靶区的跟踪和剂量场不完备的补偿；5.考虑到目前用于制定放疗计划的CT图像仍然以空间非各相同性的断层图像为主，考虑到由于脏器运动等原因造成对放疗计划的偏差需要在下次放疗中给予纠正，本发明还完成了把用于制定放疗计划的断层CT图数据集通过在三维空间内对病灶的分割、配配和显示，通过图像处理的方法把基于断层CT图像准三维图像整合后的三维剂量场与真三维剂量场的比较，其中包括对断层图像在层厚方向的非线性内插，从而保证经过反演后获得的三维空间剂量场和治疗计划规定的三维剂量场可以在相同空间分辨率的基础上进行比较和分析，为下次放疗计划的修改和进一步优化提供依据。本发明实现的方法和系统考虑了临床使用的放疗机的多样性，在应用方面具有普遍意义。A series of advanced technologies are used to realize the corresponding functions of the system: 1. According to the possibility of clinical implementation, the collimated light source and detector collect data at different angles around the patient's treatment target area. Realize within the numerical range of the angle and the finite bed rotation speed ratio, the real three-dimensional imaging (VCT) of the isotropic resolution of the patient's target area is achieved through the true three-dimensional reconstruction algorithm of the string. 2. By limiting the size of the light source and selecting a reasonable pixel size of the flat-panel detector, it is ensured that the spatial positioning of the patient's target area achieved by true three-dimensional volume imaging data is better than the positioning accuracy of tomotherapy; 3. Based on VCT imaging data, Through image segmentation and centroid calculation, the position coordinates of the patient's treatment center can be obtained (there can be more than one treatment center, subject to the doctor's prescription), and the movement of the treatment bed controlled by the program can automatically realize the positioning of the patient, in the target area In the case of movement during treatment, it dynamically tracks the movement of the target area, realizes the modeling of the target area movement, and compensates for the deterioration of the dose field distribution caused by the movement of the target area, so as to ensure the accuracy of radiotherapy in real time and dynamically. For the case of multiple treatment centers, according to the order determined in advance, the automatic tracking of the lesion position is realized respectively, and the parameters of the treatment machine are adjusted according to the dynamically optimized dose field distribution to meet the requirements of the optimized dose field distribution; 4. According to Based on the characteristics of the beam current and the shape of the treatment target area, the radiation source is modeled, and the kernel function of the light source is calculated by the Monte Carlo method. Based on the data collected during the dynamic rotation of the detector, the inversion of the treatment dose is realized. ;5. Through the comparison between the three-dimensional dose field distribution data formed in the dose inversion process and the three-dimensional dose field distribution of the treatment plan, the treatment process can control the parameters of the treatment machine, realize the optimization of the treatment process in real time, and meet the requirements of the moving target. 5. Considering that the current CT images used to make radiotherapy plans are still dominated by spatially inhomogeneous tomographic images, considering the impact of radiotherapy plans due to organ movement and other reasons The deviation needs to be corrected in the next radiotherapy. The present invention also completes the segmentation, matching and display of the tomographic CT map data set used to formulate the radiotherapy plan in three-dimensional space, and the image processing method based on the tomographic CT. The comparison between the three-dimensional dose field after the quasi-three-dimensional image integration and the real three-dimensional dose field, including the nonlinear interpolation of the tomographic image in the slice thickness direction, so as to ensure that the three-dimensional space dose field obtained after inversion is consistent with the treatment plan. The three-dimensional dose field can be compared and analyzed on the basis of the same spatial resolution, providing a basis for the modification and further optimization of the next radiotherapy plan. The method and system realized by the invention take into account the diversity of radiotherapy machines used clinically, and have universal significance in application.

Claims

1. A method for automatically positioning a patient's target area in radiation therapy, comprising the following steps:

(1) Input image data;

(2) A light source and a flat panel detector that can rotate synchronously around the patient are arranged in the treatment device;

(3) Use the light source and the flat panel detector to rotate and scan around the patient target area to obtain the image data of the patient target area, and record the corresponding data;

(4) Reconstruct and process the data to obtain an image of the patient's target area;

(5) The image data of the target area is compared with the input image data, if the positions of the two images do not match, step 6 is performed, and if the two images match, step 7 is performed;

(6) adjust the position of the patient according to the results of the comparison of the two images, and perform step 2;

(7) Continue treatment.

2. The method for automatic positioning of the patient's target area as claimed in claim 1, wherein the data in the step (3) includes: the distance A from the light source to the detector, the back projection data P, the starting point of the light source scanning track λ ₁ , the end point of light source scanning λ ₂ , the corresponding scanning angle θ ₁ when the light source scans the starting point of the trajectory, and the corresponding scanning angle θ ₂ when the light source scans the end point.

3. The method for automatic positioning of the patient's target area as claimed in claim 2, characterized in that, what the step (4) uses to process the data is a reconstruction algorithm based on chord segments, that is, when the light source scans from position 1 to position 2, the trajectory of the light source is an arc segment

f f (({x x}_{π π},, {λ λ}_{11},, {λ λ}_{22})) = = - - \frac{11}{22 π π} {&Integral; &Integral;}_{{λ λ}_{11}}^{{λ λ}_{22}} dλ dλ \frac{{A A}^{22} (({u u}_{d d},, {v v}_{d d}))}{{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |}^{22}} H h {{\frac{{P P}^{' '} (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{{A A}^{22} (({u u}_{d d}^{' '},, {v v}_{d d}^{′ ′}))}}}

- - \frac{11}{22 π π} {[[\frac{A A (({u u}_{d d},, {v v}_{d d}))}{| | \overset{&RightArrow; &Right Arrow;}{r r} - - {\overset{&RightArrow; &Right Arrow;}{r r}}_{00} ((λ λ)) | |} H h {{\frac{P P (({u u}_{d d}^{' '},, {v v}_{d d}^{' '},, λ λ))}{A A (({u u}_{d d}^{' '},, {v v}_{d d}^{' '}))}}}]]}_{{λ λ}_{11}}^{{λ λ}_{11}}

in and are right and

The Hilbert transform, in the formula

is the pair projected on the chord segment

4. the method for automatic positioning of patient's target area as claimed in claim 1, is characterized in that, in described step (5), the image data of target area and the image data of input compare by the centroid of target area, determine two image centroid and obtain the corresponding position difference.

5. The method for automatic positioning of the patient's target area as claimed in claim 1, characterized in that, in the step (6), by the control system, according to the difference between the image data of the target area and the image data of the input, move The treatment bed that carries the patient realizes the adjustment of the patient's position.