A radiotherapy positioning method

Abstract

The present invention relates to the field of radiotherapy positioning technology, in particular to a radiotherapy positioning method, comprising the following steps: S1: selecting a metal cylinder with a diameter of 10 mm and a length of 10 mm as a gold mark, fixing it on the surface of a bed perpendicularly, and evenly arranging it in rows and columns along the edges of the bed at equal intervals, and establishing a gold mark coordinate system with the surface center of the gold mark in the upper left corner of the bed as the coordinate origin, with the horizontal axis being the x-axis and the vertical axis being the y-axis; the present invention combines multiple technical points, uses the gold mark to assist in positioning the patient, and combines it with the patient's body position adjustment to jointly realize radiotherapy positioning, so that the patient can accurately locate the position of an area of ​​interest before radiotherapy, thereby ensuring that the radiotherapy operation is accurate and preventing the negative impact caused by radiotherapy positioning deviation.

Description

Technical Field

[0001] The invention relates to the technical field of radiotherapy positioning, and in particular to a radiotherapy positioning method. Background Art

[0002] At present, during radiotherapy treatment, doctors generally compare the patient's film with the patient's body during treatment, locate the patient's region of interest by manual judgment, and estimate the volume of the region of interest before performing subsequent radiotherapy operations. This method often leads to problems such as inaccurate positioning of the region of interest and angle deviation, resulting in the inability to effectively treat the region of interest during subsequent treatment, resulting in poor treatment effects.

[0003] Therefore, how to invent a radiotherapy positioning method so that the patient can accurately locate the position of the region of interest before radiotherapy, thereby ensuring the accuracy of the radiotherapy operation and preventing the negative impact caused by radiotherapy positioning deviation. Summary of the invention

[0004] The purpose of the present invention is to provide a radiotherapy positioning method to solve the above problems.

[0005] In order to achieve the above objectives, the following technical solutions are provided:

[0006] A radiotherapy positioning method is used for calibration and positioning operations before a radiotherapy process, comprising the following steps:

[0007] S1: Select a metal cylinder with a diameter of 10mm and a length of 10mm as a gold mark, fix it on the surface of the bed perpendicularly, and evenly arrange it in rows and columns along the edges of the bed at equal intervals. Establish a gold mark coordinate system with the surface center of the gold mark in the upper left corner of the bed as the coordinate origin, with the horizontal axis as the x-axis and the vertical axis as the y-axis;

[0008] The coordinates of the gold mark that is farthest from the origin of the coordinate system are defined as (x max ,y max ), the gold mark is at least fixed at (0,0) of the gold mark coordinate system, (x max ,0), (x max ,y max ), (0,y max )and At the six points, the distance between the columns of gold labels is less than 50mm, and the distance between the rows is not less than 300mm;

[0009] S2: The bed is divided into an examination bed and a treatment bed, all gold marks on the examination bed are scanned, and the data of the three-dimensional position of the gold marks in the data space are obtained for future use;

[0010] S3: Calibrate the positioning system, draw rectangular patterns on the examination bed and in the positioning system respectively, adjust the positioning so that the two overlap to complete the rough adjustment, and obtain the first adjustment coefficient; draw the gold mark data volume in S2 and project it onto the examination bed, make the gold mark projection correspond to the actual gold mark on the examination bed to complete the fine adjustment, and obtain the second adjustment coefficient;

[0011] S4: Draw a projection marker pattern through the positioning system, set a marker that coincides with the projection on the patient, and scan the patient to obtain a data set;

[0012] S5: Volume rendering of the patient data set, and adjustment through the first adjustment coefficient and the second adjustment coefficient, projecting the adjusted image and the marking graphic in S4 onto the patient, guiding the patient to adjust the body position so that the projection of the marking part and the marking graphic coincide.

[0013] Preferably, the step S3 is specifically:

[0014] S31: With the center point of the display interface in the positioning system as the center point of the rectangle, draw a standard rectangle, set the size of the rectangle to have a width of Δx=100 and a length of Δy=200, establish a coordinate system with the center point of the standard rectangle as the origin of the coordinate, select (x0, y0), (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5) as 6 rectangle control points, and the 6 rectangle control points are respectively located at the four corner points and the midpoints of the two long sides of the rectangle;

[0015] S32: Manually adjust the clarity and brightness of the positioning system and adjust the projection parameters to prevent the positioning system projection from being distorted;

[0016] S33: Establishing a bed surface coordinate system with the center point of the examination bed surface as the coordinate origin, with the x-axis and y-axis arranged along the length and width of the bed respectively, setting scales on the axis lines at fixed intervals, and drawing the coordinate system, axis lines and scales on the bed surface, and drawing a rectangle on the bed as a mark;

[0017] Among them, the fixed interval can choose mm or μm as the basic unit;

[0018] S34: Projection coarse calibration:

[0019] Project the standard rectangle in the positioning system onto the examination bed, and adjust the six rectangular control points of the standard rectangle in the positioning system until the standard rectangle and the rectangular marks of the examination bed completely overlap;

[0020] Among them, the original coordinates of the standard rectangle in the positioning system are:

[0021] (x0,y0), (x1,y1), (x2,y2), (x3,y3), (x4,y4), (x5,y5);

[0022] To match the valid mark position, coordinate adjustment is performed.

[0023] Assume the coordinates of the 6 adjusted rectangular control points are:

[0024] (x0' , y0'), (x1',y1'), (x2',y2'), (x3' , y3'), (x4' , y4'), (x5' , y5');

[0025] The original coordinates and adjusted coordinates are known quantities, and the coefficients are solved according to the following relationship:

[0026] x i '=a 00 +a 10 x i +a 01 y i +a 20 x i 2 +a 11 x i y i +a 02 y i 2 ,0≤i≤5, Formula 1

[0027] y i '=b 00 +b 10 x i +b 01 y i +b 20 x i 2 +b 11 x i y i +b 02 y i 2 ,0≤i≤5; Formula 2

[0028] The first adjustment coefficient is obtained by using equation 1 and equation 2:

[0029] [a 00 ,a 10 ,a 01 ,a 11 ,a 20 ,a 02 ,b 00 ,b 10 ,b 01 ,b 11 ,b 20 ,b02 ];

[0030] S35: Projection fine-tuning calibration:

[0031] The data of the gold mark three-dimensional position in the data space obtained in S2 is used to draw a visual image into the positioning system in a volume rendering manner through a three-dimensional rendering software. The image coordinates are (x” i ,y” i ,z” i ), adjust the coordinates of the upper left corner of the image so that it coincides with the coordinates of the upper left corner of the standard rectangle after the adjustment. At this time, the width of the image is Δx i ” and length Δy i " and the width Δx of the standard rectangle after adjusting the coordinates t ” and length Δy t "It is known that the following equations 3 and 4 are the scale coefficients, and the following equation 5 is the transformation formula. The image is proportionally transformed to a standard rectangle so that the image can be controlled by 6 rectangular control points. The adjusted image coordinates are (x" t ,y” t ,z” t );

[0032]

[0033]

[0034]

[0035] By controlling the 6 control points of the standard rectangle, adjust each gold mark pattern in the image to match the gold mark pattern on the bed surface. The coordinates of the 6 control points before adjustment are:

[0036] (x0',y0'), (x1',y1'), (x2',y2'), (x3',y3'), (x4',y4'), (x5',y5');

[0037] The coordinates of the 6 control points after adjustment are:

[0038] (x0”,y0”), (x1”,y1”), (x2”,y2”), (x3”,y3”), (x4”,y4”), (x5”,y5”);

[0039] Substitute the coordinates of the control point before adjustment into the x in equation 1 and equation 2. i ,y i ;

[0040] Substitute the adjusted control point coordinates into the x in equation 1 and equation 2. i ',y i ';

[0041] The second adjustment coefficient is obtained by using equation 1 and equation 2:

[0042] [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 '].

[0043] Preferably, the step S4 is specifically:

[0044] S41: assist the patient to lie on the examination bed, draw a marking pattern through the positioning system, and project it onto the rigid part of the patient;

[0045] Where the number of marked graphics is greater than three, the marked graphics should form a plane;

[0046] S42: making a marking piece, pasting it to the projected part of the patient, and making the marking piece completely overlap with the projected marking pattern;

[0047] S43: Scan the patient on the examination bed to form a tomographic sequence data set, and simultaneously scan at least four gold labels to obtain gold label data for auxiliary projection positioning, transmit the tomographic sequence data set to the processing system terminal, construct a three-dimensional data set for standby use;

[0048] S44: marking the voxels in the first region of interest of the three-dimensional data set as the maximum value of the voxel grayscale value, and marking the voxels outside the first region of interest as grayscale value 0, and the three-dimensional data set after this processing is recorded as data set A;

[0049] S45: construct a data set that is the same as the three-dimensional data set in S43, named as data set B, and set the grayscale values ​​of all voxels to 0;

[0050] S46: Scan the three-dimensional data set in S43 and the A data set in S44. When the grayscale value of the voxel in the A data set is not 0, the grayscale value of the voxel at the corresponding position in the three-dimensional data set is assigned to the voxel at the corresponding position in the B data set. When the grayscale value of the voxel in the A data set is 0, no operation is performed on the B data set. Repeat the above steps until the scanning is completed, and save the B data set for future use.

[0051] S47: Obtain the second region of interest in the B data set saved in S46, construct a data set identical to the three-dimensional data set in S43, named as the C data set, and set the grayscale value of the voxels in the second region of interest to the maximum value, and set the grayscale value of the voxels in non-second region of interest to 0.

[0052] Preferably, the step S5 is specifically:

[0053] S51: assist the patient to lie on the treatment bed, establish a standard rectangle copy that is the same as the standard rectangle initially drawn by the positioning system, transfer the B dataset, C dataset, and the gold label data scanned in S43 to the positioning system in a volume rendering manner, adjust the coordinates of the upper left corners of the three datasets to make them coincide with the coordinates of the standard rectangle copy, transform the three datasets to the standard rectangle copy according to the equal proportion affine transformation of S35, and select

[0054] [a 00 ,a 10 ,a 01 ,a 11 ,a 20 ,a 02 ,b 00 ,b 10 ,b 01 ,b 11 ,b 20 ,b 02 ]and

[0055] [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 '] as coefficient,

[0056] After adjusting the standard rectangular copy according to Formula 1 and Formula 2, the image is projected onto the patient on the treatment couch, and auxiliary calibration is performed through gold mark projection;

[0057] S52: Projecting the marking graphic in the positioning system onto the patient on the treatment bed again, and guiding the patient to adjust the body position so that the projection of the marking graphic completely overlaps with the marking element.

[0058] The beneficial effects of the present invention are:

[0059] 1. The present invention combines multiple technical points, uses a gold marker to assist in locating the patient's position, and combines it with the patient's body position adjustment to achieve radiotherapy positioning, so that the patient can accurately locate the position of the area of ​​interest before radiotherapy, thereby ensuring that the radiotherapy operation is accurate and preventing the negative impact caused by radiotherapy positioning deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a flow chart of the calibration and positioning system of the present invention;

[0061] Figure 2 It is a schematic diagram of the gold mark calibration position of the bed body of the present invention;

[0062] Figure 3 It is a schematic diagram of the marking graphics and marking projection process built into the positioning system of the present invention;

[0063] Figure 4 This is a schematic diagram of a usage scenario of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the schematic diagrams 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.

[0065] like Figure 1-4 As shown, a radiotherapy positioning method is used for calibration positioning operations before the radiotherapy process, comprising the following steps:

[0066] S1: Select a metal cylinder with a diameter of 10mm and a length of 10mm as a gold mark, fix it on the surface of the bed perpendicularly, and evenly arrange it in rows and columns along the edges of the bed at equal intervals. Establish a gold mark coordinate system with the surface center of the gold mark in the upper left corner of the bed as the coordinate origin, with the horizontal axis as the x-axis and the vertical axis as the y-axis;

[0067] Define the coordinates of the gold mark that is farthest from the origin of the coordinate as (x max ,y max ), the gold mark is at least fixed at (0,0) of the gold mark coordinate system, (x max ,0), (x max ,y max ), (0,y max )and At the six points, the distance between the columns of gold labels is less than 50mm, and the distance between the rows is not less than 300mm;

[0068] S2: The bed is divided into an examination bed and a treatment bed, all gold marks on the examination bed are scanned, and the data of the three-dimensional position of the gold marks in the data space are obtained for future use;

[0069] S3: Calibrate the positioning system, draw rectangular patterns on the examination bed and in the positioning system respectively, adjust the positioning so that the two overlap to complete the rough adjustment, and obtain the first adjustment coefficient; draw the gold mark data volume in S2 and project it onto the examination bed, make the gold mark projection correspond to the actual gold mark on the examination bed to complete the fine adjustment, and obtain the second adjustment coefficient;

[0070] S4: Draw a projection marker pattern through the positioning system, set a marker that coincides with the projection on the patient, and scan the patient to obtain a data set;

[0071] S5: Volume rendering the patient data set, and adjusting it by using the first adjustment coefficient and the second adjustment coefficient, projecting the adjusted image and the marking graphic in S4 onto the patient, and guiding the patient to adjust the body position so that the projection of the marking part and the marking graphic coincide;

[0072] In some embodiments, step S3 is specifically:

[0073] S31: With the center point of the display interface in the positioning system as the center point of the rectangle, draw a standard rectangle, set the size of the rectangle to have a width of Δx=100 and a length of Δy=200, establish a coordinate system with the center point of the standard rectangle as the origin of the coordinate, select (x0, y0), (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5) as 6 rectangle control points, and the 6 rectangle control points are respectively located at the four corner points and the midpoints of the two long sides of the rectangle;

[0074] S32: Manually adjust the clarity and brightness of the positioning system and adjust the projection parameters to prevent the positioning system projection from being distorted;

[0075] S33: Establishing a bed surface coordinate system with the center point of the examination bed surface as the coordinate origin, with the x-axis and y-axis arranged along the length and width of the bed respectively, setting scales on the axis lines at fixed intervals, and drawing the coordinate system, axis lines and scales on the bed surface, and drawing a rectangle on the bed as a mark;

[0076] Fixed intervals can choose mm or μm as the basic unit;

[0077] S34: Projection coarse calibration:

[0078] Project the standard rectangle in the positioning system onto the examination bed, and adjust the six rectangular control points of the standard rectangle in the positioning system until the standard rectangle and the rectangular marks of the examination bed completely overlap;

[0079] The original coordinates of the standard rectangle in the positioning system are:

[0080] (x0,y0), (x1,y1), (x2,y2), (x3,y3), (x4,y4), (x5,y5);

[0081] To match the valid mark position, coordinate adjustment is performed.

[0082] Assume the coordinates of the 6 adjusted rectangular control points are:

[0083] (x0',y0'), (x1',y1'), (x2',y2'), (x3',y3'), (x4',y4'), (x5',y5');

[0084] The original coordinates and adjusted coordinates are known quantities, and the coefficients are solved according to the following relationship:

[0085] x i '=a 00 +a 10 x i +a 01 y i +a 20 x i 2 +a 11 x i y i +a 02 y i 2 ,0≤i≤5, Formula 1

[0086] y i '=b 00 +b 10 x i +b 01 y i +b 20 x i 2 +b 11 x i y i +b 02 y i 2 ,0≤i≤5; Formula 2

[0087] The first adjustment coefficient is obtained by equation 1 and equation 2:

[0088] [a 00 ,a 10 ,a 01 ,a 11 ,a 20 ,a 02 ,b 00 ,b 10 ,b 01 ,b11 ,b 20 ,b 02 ];

[0089] S35: Projection fine-tuning calibration:

[0090] The data of the gold mark three-dimensional position in the data space obtained in S2 is used to draw a visual image into the positioning system in a volume rendering manner through a three-dimensional rendering software. The image coordinates are (x” i ,y” i ,z” i ), adjust the coordinates of the upper left corner of the image so that it coincides with the coordinates of the upper left corner of the standard rectangle after the adjustment. At this time, the width of the image is Δx i ” and length Δy i " and the width Δx of the standard rectangle after adjusting the coordinates t ” and length Δy t "It is known that the following equations 3 and 4 are the scale coefficients, and the following equation 5 is the transformation formula. The image is proportionally transformed to a standard rectangle so that the image can be controlled by 6 rectangular control points. The adjusted image coordinates are (x t ”,y t ”,z t ”);

[0091]

[0092]

[0093]

[0094] By controlling the 6 control points of the standard rectangle, adjust each gold mark pattern in the image to match the gold mark pattern on the bed surface. The coordinates of the 6 control points before adjustment are:

[0095] (x0',y0'), (x1',y1'), (x2',y2'), (x3',y3'), (x4',y4'), (x5',y5');

[0096] The coordinates of the 6 control points after adjustment are:

[0097] (x0”,y0”), (x1”,y1”), (x2”,y2”), (x3”,y3”), (x4”,y4”), (x5”,y5”);

[0098] Substitute the coordinates of the control point before adjustment into the x in equation 1 and equation 2. i ,y i ;

[0099] Substitute the adjusted control point coordinates into x in Equation 1 and Equation 2 i ',yi ';

[0100] The second adjustment coefficient is obtained by equation 1 and equation 2:

[0101] [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 '];

[0102] After the above calibration process, the relationship between the three-dimensional rendering image in the positioning system and the bed surface is maintained at a 1:1 fixed relationship. During the patient's tomography scanning process, the obtained tomographic resolution and scanning accuracy parameters between tomography can display the distance relationship between pixels in the image space as a physical scale distance relationship, and accurately mark the physical distance between tissues in the projection image;

[0103] In some embodiments, step S4 is specifically:

[0104] S41: assist the patient to lie on the examination bed, draw a marking pattern through the positioning system, and project it onto the rigid part of the patient;

[0105] The marking shape can be selected from the system. Through the spatial position relationship between the marking shape and various marking points, the patient is guided to adjust the body position so that the marking points and the reference points in the ruler all coincide with each other, ensuring that the human body state is exactly the same as that during the examination. The selected rigid parts can be selected such as shoulders, chest, ribs, ilium, etc.

[0106] If the number of marked graphics is greater than three, the marked graphics should form a plane;

[0107] S42: making a marking piece, pasting it to the projected part of the patient, and making the marking piece completely overlap with the projected marking pattern;

[0108] S43: Scan the patient on the examination bed to form a tomographic sequence data set, and simultaneously scan at least four gold labels to obtain gold label data for auxiliary projection positioning, transmit the tomographic sequence data set to the processing system terminal, construct a three-dimensional data set for standby use;

[0109] The processing system terminal is a computer system that uses the existing graphic GDI technology and has the ability to communicate with the hospital PACS system or an independent DICOM workstation. The system is a Windows operating system. The processing system terminal can read medical imaging data in the network environment, process three-dimensional tomographic data, realize three-dimensional visualization drawing functions, and control projection equipment to complete projection and calibration functions;

[0110] S44: marking the voxels in the first region of interest of the three-dimensional data set as the maximum value of the voxel grayscale value, and marking the voxels outside the first region of interest as grayscale value 0, and the three-dimensional data set after this processing is recorded as data set A;

[0111] The first region of interest can be calculated from the three-dimensional data set by a neural network algorithm;

[0112] S45: construct a data set that is the same as the three-dimensional data set in S43, named as data set B, and set the grayscale values ​​of all voxels to 0;

[0113] S46: Scan the three-dimensional data set in S43 and the A data set in S44. When the grayscale value of the voxel in the A data set is not 0, the grayscale value of the voxel at the corresponding position in the three-dimensional data set is assigned to the voxel at the corresponding position in the B data set. When the grayscale value of the voxel in the A data set is 0, no operation is performed on the B data set. Repeat the above steps until the scanning is completed, and save the B data set for future use.

[0114] S47: obtaining the second region of interest in the B data set stored in S46, constructing a data set identical to the three-dimensional data set in S43, named as the C data set, and setting the grayscale value of the voxels in the second region of interest to the maximum value, and setting the grayscale value of the voxels in the non-second region of interest to 0;

[0115] The initial grayscale value of the second region of interest can be obtained by a grayscale average algorithm or set interactively, and the growth strategy is set according to specific medical device parameters;

[0116] In some embodiments, step S5 is specifically:

[0117] S51: assist the patient to lie on the treatment bed, establish a standard rectangle copy that is the same as the standard rectangle initially drawn by the positioning system, transfer the B dataset, C dataset, and the gold label data scanned in S43 to the positioning system in a volume rendering manner, adjust the coordinates of the upper left corners of the three datasets to make them coincide with the coordinates of the standard rectangle copy, transform the three datasets to the standard rectangle copy according to the equal proportion affine transformation of S35, and select

[0118] [a 00 ,a 10 ,a 01 ,a 11,a 20 ,a 02 ,b 00 ,b 10 ,b 01 ,b 11 ,b 20 ,b 02 ]and

[0119] [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 '] as coefficient,

[0120] After adjusting the standard rectangular copy according to equations 1 and 2, the image is projected onto the patient on the treatment bed, and auxiliary calibration is performed through gold standard projection;

[0121] S52: Projecting the marking graphic in the positioning system onto the patient on the treatment bed again, and guiding the patient to adjust the body position so that the projection of the marking graphic completely overlaps with the marking element.

Claims

1. A radiotherapy positioning method, used for calibration and positioning operations before radiotherapy, characterized in that: The following steps are involved: S1: Select a metal cylinder with a diameter of 10mm and a length of 10mm as a gold mark, fix it on the surface of the bed perpendicularly, and evenly arrange it in rows and columns along the edges of the bed at equal intervals. Establish a gold mark coordinate system with the surface center of the gold mark in the upper left corner of the bed as the coordinate origin, with the horizontal axis as the x-axis and the vertical axis as the y-axis; The coordinates of the gold mark that is farthest from the origin of the coordinate system are defined as (x max ,y max ), the gold mark is at least fixed at (0,0) of the gold mark coordinate system, (x max ,0), (x max ,y max ), (0,y max )and At the six points, the distance between the columns of gold labels is less than 50mm, and the distance between the rows is not less than 300mm; S2: The bed is divided into an examination bed and a treatment bed, all gold marks on the examination bed are scanned, and the data of the three-dimensional position of the gold marks in the data space are obtained for future use; S3: Calibrate the positioning system, draw rectangular patterns on the examination bed and in the positioning system respectively, adjust the positioning so that the two overlap to complete the rough adjustment, and obtain the first adjustment coefficient; draw the gold mark data volume in S2 and project it onto the examination bed, make the gold mark projection correspond to the actual gold mark on the examination bed to complete the fine adjustment, and obtain the second adjustment coefficient; S4: Draw a projection marker pattern through the positioning system, set a marker that coincides with the projection on the patient, and scan the patient to obtain a data set; S5: Volume rendering the patient data set, and adjusting it by using the first adjustment coefficient and the second adjustment coefficient, projecting the adjusted image and the marking graphic in S4 onto the patient, and guiding the patient to adjust the body position so that the projection of the marking part and the marking graphic coincide; The step S3 is specifically as follows: S31: With the center point of the display interface in the positioning system as the center point of the rectangle, draw a standard rectangle, set the size of the rectangle to have a width of Δx=100 and a length of Δy=200, establish a coordinate system with the center point of the standard rectangle as the origin of the coordinate, select (x0, y0), (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5) as 6 rectangle control points, and the 6 rectangle control points are respectively located at the four corner points and the midpoints of the two long sides of the rectangle; S32: Manually adjust the clarity and brightness of the positioning system and adjust the projection parameters to prevent the positioning system projection from being distorted; S33: Establishing a bed surface coordinate system with the center point of the examination bed surface as the coordinate origin, with the x-axis and y-axis arranged along the length and width of the bed respectively, setting scales on the axis lines at fixed intervals, and drawing the coordinate system, axis lines and scales on the bed surface, and drawing a rectangle on the bed as a mark; Among them, the fixed interval can choose mm or μm as the basic unit; S34: Projection coarse calibration: Project the standard rectangle in the positioning system onto the examination bed, and adjust the six rectangular control points of the standard rectangle in the positioning system until the standard rectangle and the rectangular marks of the examination bed completely overlap; Among them, the original coordinates of the standard rectangle in the positioning system are: (x0,y0), (x1,y1), (x2,y2), (x3,y3), (x4,y4), (x5,y5); To match the valid mark position, coordinate adjustment is performed. Assume the coordinates of the 6 adjusted rectangular control points are: (x0',y0'), (x1',y1'), (x2',y2'), (x3',y3'), (x4',y4'), (x5',y5'); The original coordinates and adjusted coordinates are known quantities, and the coefficients are solved according to the following relationship: x i ' = a 00 + a 10 x i + a 01 y i + a 20 x i 2 + a 11 x i y i + a 02 y i 2 , 0 ≤ i ≤ 5, Equation 1 y i ' = b 00 + b 10 x i + b 01 y i + b 20 x i 2 + b 11 x i y i + b 02 y i 2 , 0 ≤ i ≤ 5; Equation 2 The first adjustment coefficient is obtained by using equation 1 and equation 2: [a 00 ,a 10 ,a 01 ,a 11 ,a 20 ,a 02 ,b 00 ,b 10 ,b 01 ,b 11 ,b 20 ,b 02 ]; S35: Projection fine-tuning calibration: The data of the gold mark three-dimensional position in the data space obtained in S2 is used to draw a visual image into the positioning system in a volume rendering manner through a three-dimensional rendering software. The image coordinates are (x' i ',y' i ',z i ”), adjust the coordinates of the upper left corner of the image so that it coincides with the coordinates of the upper left corner of the standard rectangle after the adjustment. At this time, the width of the image is Δx i ” and length Δy i " and the width Δx of the standard rectangle after adjusting the coordinates t ” and length Δy t "It is known that the following equations 3 and 4 are the scale coefficients, and the following equation 5 is the transformation formula. The image is proportionally transformed to a standard rectangle so that the image can be controlled by 6 rectangular control points. The adjusted image coordinates are (x t ”,y t ”,z t ”); By controlling the 6 control points of the standard rectangle, adjust each gold mark pattern in the image to match the gold mark pattern on the bed surface. The coordinates of the 6 control points before adjustment are: (x0',y0'), (x1',y1'), (x2',y2'), (x3',y3'), (x4',y4'), (x5',y5'); The coordinates of the 6 control points after adjustment are: (x0”,y0”), (x1”,y1”), (x2”,y2”), (x3”,y3”), (x4”,y4”), (x5”,y5”); Substitute the coordinates of the control point before adjustment into the x in equation 1 and equation 2. i ,y i ; Substitute the adjusted control point coordinates into the x in equation 1 and equation 2. i ',y i '; The second adjustment coefficient is obtained by using equation 1 and equation 2: [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 ']。 2. A radiotherapy positioning method according to claim 1, characterized in that: The step S4 is specifically as follows: S41: assist the patient to lie on the examination bed, draw a marking pattern through the positioning system, and project it onto the rigid part of the patient; Where the number of marked graphics is greater than three, the marked graphics should form a plane; S42: making a marking piece, pasting it to the projected part of the patient, and making the marking piece completely overlap with the projected marking pattern; S43: Scan the patient on the examination bed to form a tomographic sequence data set, and simultaneously scan at least four gold labels to obtain gold label data for auxiliary projection positioning, transmit the tomographic sequence data set to the processing system terminal, construct a three-dimensional data set for standby use; S44: marking the voxels in the first region of interest of the three-dimensional data set as the maximum value of the voxel grayscale value, and marking the voxels outside the first region of interest as grayscale value 0, and the three-dimensional data set after this processing is recorded as data set A; S45: construct a data set that is the same as the three-dimensional data set in S43, named as data set B, and set the grayscale values ​​of all voxels to 0; S46: Scan the three-dimensional data set in S43 and the A data set in S44. When the grayscale value of the voxel in the A data set is not 0, the grayscale value of the voxel at the corresponding position in the three-dimensional data set is assigned to the voxel at the corresponding position in the B data set. When the grayscale value of the voxel in the A data set is 0, no operation is performed on the B data set. Repeat the above steps until the scanning is completed, and save the B data set for future use. S47: Obtain the second region of interest in the B data set saved in S46, construct a data set identical to the three-dimensional data set in S43, named as the C data set, and set the grayscale value of the voxels in the second region of interest to the maximum value, and set the grayscale value of the voxels in non-second region of interest to 0.

3. A radiotherapy positioning method according to claim 2, characterized in that: The step S5 is specifically as follows: S51: assist the patient to lie on the treatment bed, establish a standard rectangle copy that is the same as the standard rectangle initially drawn by the positioning system, transfer the B dataset, C dataset, and the gold label data scanned in S43 to the positioning system in a volume rendering manner, adjust the coordinates of the upper left corners of the three datasets to make them coincide with the coordinates of the standard rectangle copy, transform the three datasets to the standard rectangle copy according to the equal proportion affine transformation of S35, and select [a 00 , a 10 , a 01 , a 11 , a 20 , a 02 , b 00 , b 10 , b 01 , b 11 , b 20 , b 02 and [a 00 ',a 10 ',a 01 ',a 11 ',a 20 ',a 02 ',b 00 ',b 10 ',b 01 ',b 11 ',b 20 ',b 02 ']Working number, After adjusting the standard rectangular copy according to Formula 1 and Formula 2, the image is projected onto the patient on the treatment couch, and auxiliary calibration is performed through gold mark projection; S52: Projecting the marking graphic in the positioning system onto the patient on the treatment bed again, and guiding the patient to adjust the body position so that the projection of the marking graphic completely overlaps with the marking element.

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