Disclosure of Invention
In order to solve the above problems in the prior art, the present invention is directed to a path planning and needle generation method for radioactive particle source implantation in a tumor.
The technical scheme adopted by the invention is as follows:
a needle path planning and needle path generating method for radioactive particle source implantation in a tumor body comprises parallel needle path planning and needle path generation;
the parallel needle path planning and needle path generation method comprises the following steps:
s101, performing linear horizontal arrangement of radioactive particle sources in a tumor;
s102, dividing the tumor into a plurality of squares according to the linear and horizontal arrangement direction of the radioactive particle sources;
s103, selecting a point in the three-dimensional space as a central point, and taking a Z axis passing through the central point as a central line;
s104, rotating the tumor for one circle by taking the central point as a center, and setting an included angle between a rotating surface and the central line as α;
s105, adjusting an included angle between the rotating surface and the central line to continuously rotate for a circle by taking the central point as a center, wherein the normal of the rotating surface passing through the central point and the central line are always positioned on the same plane;
s106, circularly executing S105 until the included angle between the rotating surface and the central line is α plus 180 degrees;
s107, adjusting the rotation radius, and executing S104-S106;
s108, circularly executing S107 until the rotating radius exceeds a set value;
and S109, in the rotating process, taking Q identical rotating angles on each rotating radius, recording the total number of the squares penetrating through the organs and tissues endangered outside the tumor, taking the rotating angle corresponding to the minimum total number of the squares penetrating through the organs and tissues endangered outside the tumor, and generating a needle track by taking the central line of each square of the tumor as a linear datum line at the rotating angle.
On the basis of the technical scheme, the method for planning the needle path for implanting the radioactive particle source into the tumor and generating the needle path further comprises free-angle needle path planning and needle path generation;
the free angle needle path planning and needle path generation method comprises the following steps:
s201, carrying out free arrangement of radioactive particle sources in the tumor, and recording a rotation angle during free arrangement;
s202, generating a needle channel according to the rotation angle recorded in the radioactive particle source free arrangement step, extending the needle channel outwards, if the extending section does not penetrate through organs and tissues endangered outside the tumor body, keeping the needle channel, and if not, deleting the needle channel and carrying out free arrangement on the radioactive particle sources again.
Based on the above technical scheme, the square in S102 is X × 1cm, and X is the length, width or height of the tumor.
On the basis of the technical scheme, the tumor is a well-segmented tumor surface drawing model.
On the basis of the technical scheme, the well-segmented tumor surface drawing model is manufactured in the following mode:
a1, obtaining a plurality of tomograms of a target part, preprocessing the tomograms, dividing the tomograms into a target part region and a region outside the target part, removing the region outside the target part, labeling tumor tissues and other tissues in the target part region, labeling organs and tissues endangered in the tumor body, obtaining a plurality of labeled samples, and storing the labeled samples to obtain a data set;
a2, establishing a 3D convolutional neural network model, inputting all labeled sample data information into the 3D convolutional neural model for training, and outputting a trained 3D convolutional neural deep learning model;
a3, preprocessing a tomography map of the target part, dividing the tomography map into a target part area and an area outside the target part, and removing the area outside the target part;
a4, inputting the preprocessed tomography scanning map data information into the trained 3D convolution nerve deep learning model, outputting the segmented 3D cube data, and combining the segmented 3D cube data to obtain the segmented tumor surface drawing model.
On the basis of the technical scheme, the linear horizontal arrangement of the radioactive particle sources comprises the following steps:
s1011, extracting the tumor filled with the radioactive particle source;
s1012, dividing the tumor into a plurality of squares of X1 cm, wherein X is the length, width or height value of the tumor, and respectively taking the central line of each square as a linear datum line;
s1013, absorbing the radioactive particle source in a set value range from the central line of the square into the square, correcting the central point of the radioactive particle source in the absorbed square onto the linear reference line of the square, and moving each radioactive particle source only once;
and S1014, detecting the distance between the moved radioactive particles, and deleting the moved radioactive particle sources when a plurality of radioactive particle sources are overlapped and intersected or the distance is smaller than a set value.
On the basis of the technical scheme, the set value in S1013 is 1cm, and the set value in S1014 is 5 mm.
On the basis of the technical scheme, the free arrangement of the radioactive particle sources comprises the following steps:
s2011a, using the radioactive particle source at the bottom of the tumor as the center point, and using the Z-axis passing through the center point as the center line to create a virtual cylinder of 1 × Zcm;
s2012a, tilting the virtual column by S ° about the central line and rotating the virtual column for one circle, sucking 2 or more free radioactive particle sources into the virtual column if the radioactive particle sources are detected to be in the virtual column during the rotation, correcting the central point of the radioactive particle sources sucked into the virtual column to the central line of the virtual column, and recording the rotation angle;
s2013a, inclining the X axis for S degrees again and rotating for a circle, sucking the free radioactive particle source into the virtual column, correcting the central point of the radioactive particle source sucked into the virtual column to the central line of the virtual column to stop moving, and recording the rotating angle;
s2014a, executing S2013a in a loop until the virtual cylinder does not intersect with the tumor;
s2015a, when stopping, counting whether the free radioactive particle source has completely moved, if so, ending; if not, adjusting the degree of inclination to the X axis each time, and performing a recycling operation S2012a-S2015a until the free radioactive particle source is completely moved;
s2016a, detecting the distance between the moved radioactive seeds, and if the multiple radioactive seed sources overlap each other or the distance is less than a predetermined value, deleting the moved radioactive seed sources.
On the basis of the technical scheme, the free arrangement of the radioactive particle sources comprises the following steps:
s2011b, a virtual cylinder is created by taking a point outside the tumor right below the center point of the tumor as an origin and taking a Z axis passing through the origin as a central line;
s2012b, tilting the virtual column by t ° about the central line to the X axis and rotating the virtual column for a circle, and if 2 or more free radioactive particle sources are detected in the virtual column during the rotation, sucking the free radioactive particle sources into the virtual column, correcting the central point of the radioactive particle sources sucked into the virtual column to the central line of the virtual column, and recording the rotation angle;
s2013b, inclining the X axis for t degrees again and rotating for a circle, sucking the free radioactive particle source into the virtual column, correcting the central point of the radioactive particle source sucked into the virtual column to the central line of the virtual column to stop moving, and recording the rotating angle;
s2014b, executing S2013b in a loop until the virtual cylinder does not intersect with the tumor;
s2015b, when stopping, counting whether the free radioactive particle source has completely moved, if so, ending; if not, adjusting the degree of inclination to the X axis each time, and performing a recycling operation S2012b-S2015b until the free radioactive particle source is completely moved;
s2016b, detecting the distance between the moved radioactive particles, and deleting the moved radioactive particle sources when a plurality of radioactive particle sources overlap and intersect or the distance is less than a set value
On the basis of the technical scheme, radioactive particle sources in organs and tissues endangered in a tumor body are further processed after the radioactive particle sources are linearly and horizontally arranged and freely arranged;
the radioactive particle source treatment of organs and tissues at risk in the tumor comprises the following steps:
performing collision detection and distance measurement on the arranged radioactive particle sources and organs and tissues endangered in the tumor body, and if the central point of a certain radioactive particle source penetrates through the organs and tissues endangered in the tumor body or the shortest distance between the central point of a certain radioactive particle source and the organs and tissues endangered in the tumor body is smaller than a set value, regarding the radioactive particle source as an invalid radioactive particle source, and deleting the radioactive particle source; otherwise, the radioactive particle source is effectively radioactive particle source and is reserved.
The invention has the beneficial effects that:
the invention considers the insertion difficulty of the implantation needle, reasonably plans the needle path, and can bypass some tissues or sclerotin, thereby avoiding causing additional damage to other tissues of the body and reducing the damage degree to normal tissues on the premise of ensuring better treatment effect.
Example (b):
as shown in fig. 1, the needle path planning and needle path generating method for implanting radioactive particle sources in tumor bodies of the present embodiment includes parallel needle path planning and needle path generation, and free angle needle path planning and needle path generation;
the parallel needle path planning and needle path generation method comprises the following steps:
s101, performing linear horizontal arrangement of radioactive particle sources in a tumor, wherein the tumor is a well-segmented tumor surface drawing model;
s102, dividing the tumor into a plurality of X1 cm squares according to the linear and horizontal arrangement direction of radioactive particle sources, wherein X is the length, width or height value of the tumor;
s103, selecting a point in the three-dimensional space as a central point, and taking a Z axis passing through the central point as a central line;
s104, rotating the tumor for one circle by taking the central point as a center, and setting an included angle between a rotating surface and the central line as α;
s105, adjusting an included angle between the rotating surface and the central line to continuously rotate for a circle by taking the central point as a center, wherein the normal of the rotating surface passing through the central point and the central line are always positioned on the same plane;
s106, circularly executing S105 until the included angle between the rotating surface and the central line is α plus 180 degrees;
s107, adjusting the rotation radius, and executing S104-S106;
s108, circularly executing S107 until the rotating radius exceeds a set value;
and S109, in the rotating process, taking Q identical rotating angles on each rotating radius, recording the total number of the squares penetrating through the organs and tissues endangered outside the tumor, taking the rotating angle corresponding to the minimum total number of the squares penetrating through the organs and tissues endangered outside the tumor, and generating a needle track by taking the central line of each square of the tumor as a linear datum line at the rotating angle.
The free angle needle path planning and needle path generation method comprises the following steps:
s201, radioactive particle sources are arranged in a tumor in a free mode, the rotating angle of the radioactive particle sources in the free mode is recorded, and the tumor is a well-segmented tumor surface drawing model;
s202, generating a needle channel according to the rotation angle recorded in the radioactive particle source free arrangement step, extending the needle channel outwards, if the extending section does not penetrate through organs and tissues endangered outside the tumor body, keeping the needle channel, and if not, deleting the needle channel and carrying out free arrangement on the radioactive particle sources again.
The invention considers the insertion difficulty of the implantation needle, reasonably plans the needle path, and can bypass some tissues or sclerotin, thereby avoiding causing additional damage to other tissues of the body and reducing the damage degree to normal tissues on the premise of ensuring better treatment effect.
The preparation method of the segmented tumor surface drawing model is as follows:
a1, obtaining a plurality of tomograms of a target part, preprocessing the tomograms, dividing the tomograms into a target part region and a region outside the target part, removing the region outside the target part, labeling tumor tissues and other tissues in the target part region, labeling organs and tissues endangered in the tumor body, obtaining a plurality of labeled samples, and storing the labeled samples to obtain a data set;
a2, establishing a 3D convolutional neural network model, inputting all labeled sample data information into the 3D convolutional neural model for training, and outputting a trained 3D convolutional neural deep learning model;
a3, preprocessing a tomography map of the target part, dividing the tomography map into a target part area and an area outside the target part, and removing the area outside the target part;
a4, inputting the preprocessed tomography scanning map data information into the trained 3D convolution nerve deep learning model, outputting the segmented 3D cube data, and combining the segmented 3D cube data to obtain the segmented tumor surface drawing model.
The specific implementation of the pretreatment is as follows:
a31, standardizing pixel values of the image, and making probability density distribution on the pixel values;
a32, finding boundaries among tissues in different areas according to the distribution of pixel values, and distinguishing tumor tissue areas from other tissue areas;
a33, connecting other tissue areas into a whole to make a tomography map mask;
a34, multiplying the original three-dimensional labeling data point by the corresponding image mask information to obtain the data of only other tissue area images.
The specific implementation manner for distinguishing the target part region from the region outside the target part is as follows:
a321, reading and identifying color values of different areas on the tomography, collecting and sorting the color values corresponding to the regional tissues of the target part and the color values corresponding to the regional tissues outside the target part to obtain a color value interval corresponding to the regional tissues of the target part and a color value interval corresponding to the regional tissues outside the target part, and taking the color value intervals as a standard for distinguishing the regional tissues of the target part and the regional tissues outside the target part.
The tomographic mask is produced as follows:
a331, making the regions other than the target region as continuous as possible by erosion processing and expansion processing in the morphological processing, and eliminating the specific color value portion in the target region as much as possible to complete the mask of the target region.
The content of the label comprises coordinate information, the coordinate information is generated based on a coordinate system on the tomography image where the label is located and is used for marking the relative position of the tumor tissue on the tomography image, the coordinate system is a three-dimensional Cartesian coordinate system, and the relative position of the tumor tissue and other tissues on each tomography image is represented by the three-dimensional Cartesian coordinate system.
The marked content also comprises identification information, the identification information is used for marking the tissue at the current position as tumor tissue or other tissues, the identification information is matched with the coordinate information, and the identification information of the tissue corresponding to the current position is given to the coordinate information of the tissue corresponding to the current position.
The 3D convolutional neural network model is mainly constructed in a mode of combining a U-net segmentation network and a Res-net residual error network. The shallow network of the model mainly stores the position information of the pixels, the deep network mainly stores the classification information of the pixels, and the U-net network and the Res-net network can supplement the shallow information to the deep layer, so that the positioning accuracy and the classification accuracy of image pixel segmentation are ensured; meanwhile, the Res-net network structure changes the learning target from the output of the learning model to the difference between the learning input and the learning output, so that the learning difficulty of the network model is reduced, and the model can be converged more quickly.
Before performing 3D convolutional neural network model training, the three-dimensional data in the labeled sample data information is cut into 3D cubic blocks of data of pixels 256 × 256 (or 128 × 128, 64 × 64) for training. Because the three-dimensional data contains information between slice layers, the accuracy of the result can be improved by using the three-dimensional data to perform 3D convolutional neural network training.
In addition, in this embodiment, taking 256 × 2563D cubic block units as an example, the total number of layers of the 3D convolutional neural network model design reaches 160, specifically: carrying out convolution on the 256 × 256 cubic block units and + BN + maxpool to extract features to obtain a feature map, and adding a residual block by combining a residual network (Res-net); extracting feature reduction feature maps to 16 × 16, and increasing channels to 64; and then, amplifying the feature maps to 256 × 256 by using a deconvolution combined residual error method, and merging the feature maps in the same position by using a cat method in a U-net network in the process of amplifying the feature maps by deconvolution to finally obtain a segmented tumor surface drawing model.
The linear horizontal arrangement of the radioactive particle sources comprises the following steps:
s1011, extracting the tumor filled with the radioactive particle source;
s1012, dividing the tumor into a plurality of squares of X1 cm, wherein X is the length, width or height value of the tumor, and respectively taking the central line of each square as a linear datum line;
s1013, absorbing the radioactive particle source in a set value range from the central line of the square into the square, and correcting the central point of the radioactive particle source in the absorbed square onto the linear reference line of the square, wherein each radioactive particle source only moves once, and the set value is generally 1 cm;
s1014, detecting the distance between the moved radioactive particles, and deleting the moved radioactive particle source when a plurality of radioactive particle sources overlap and intersect or the distance is smaller than a set value, which is generally 5 mm.
The radioactive particle source free arrangement comprises the following steps:
s2011a, using the radioactive particle source at the bottom of the tumor as the center point, and using the Z-axis passing through the center point as the center line to create a virtual cylinder of 1 × Zcm;
s2012a, tilting the virtual cylinder by S ° about the central line and rotating the virtual cylinder for one circle, sucking 2 or more free (non-linear) radioactive particle sources into the virtual cylinder if the radioactive particle sources are detected to be in the virtual cylinder during the rotation, correcting the central point of the radioactive particle sources sucked into the virtual cylinder to the central line of the virtual cylinder, and recording the rotation angle;
s2013a, inclining the X axis for S degrees again and rotating for a circle, sucking a free (nonlinear) radioactive particle source into the virtual column, correcting the central point of the radioactive particle source sucked into the virtual column to the central line of the virtual column, and recording the rotating angle;
s2014a, executing S2013a in a loop until the virtual cylinder does not intersect with the tumor;
s2015a, when the operation is stopped, counting whether all the radioactive particle sources have moved, and if yes, ending the operation; if not, adjusting the degree of inclination to the X-axis each time, performing S2012a-S2015a in a recycling manner until the free (non-linear) radioactive particle source is completely moved;
s2016a, detecting the distance between the moved radioactive seeds, wherein the set value of the moved radioactive seed source after deletion is generally 5mm when a plurality of radioactive seed sources overlap each other or the distance is less than the set value.
Another radioactive particle source free arrangement comprises the following steps:
s2011b, a virtual cylinder is created by taking a point outside the tumor right below the center point of the tumor as an origin and taking a Z axis passing through the origin as a central line;
s2012b, tilting the virtual column by t ° about the central line to the X axis and rotating the virtual column for a circle, and if 2 or more free (non-linear) radioactive particle sources are detected in the virtual column during the rotation, sucking the radioactive particle sources into the virtual column, correcting the central point of the radioactive particle sources sucked into the virtual column to the central line of the virtual column, and recording the rotation angle;
s2013b, inclining the X axis for t degrees again and rotating for a circle, sucking a free (nonlinear) radioactive particle source into the virtual column, correcting the central point of the radioactive particle source sucked into the virtual column to the central line of the virtual column, and recording the rotating angle;
s2014b, executing S2013b in a loop until the virtual cylinder does not intersect with the tumor;
s2015b, when the operation is stopped, counting whether all the radioactive particle sources have moved, and if yes, ending the operation; if not, adjusting the degree of inclination to the X-axis each time, performing a recycling operation S2012b-S2015b until the free (non-linear) radioactive particle source has moved completely;
s2016b, detecting the distance between the moved radioactive particles, and when a plurality of radioactive particle sources overlap and intersect or the distance is smaller than a set value, deleting the moved radioactive particle sources, and calculating the total number of radioactive particle sources required by the tumor, wherein the set value is generally 5 mm.
After the radioactive particle source linear horizontal arrangement and radioactive particle source free arrangement steps, radioactive particle source treatment of organs and tissues endangered in the tumor is also carried out:
performing collision detection and distance measurement on the arranged radioactive particle sources and organs and tissues endangered in the tumor body, and if the central point of a certain radioactive particle source penetrates through the organs and tissues endangered in the tumor body or the shortest distance between the central point of a certain radioactive particle source and the organs and tissues endangered in the tumor body is smaller than a set value, regarding the radioactive particle source as an invalid radioactive particle source, and deleting the radioactive particle source; otherwise, the radioactive particle source is effectively radioactive particle source and is reserved.
The method for filling the radioactive particle source comprises the following steps: random filling method or linear filling method for radioactive particle source in tumor.
The random filling method of radioactive particle sources in the tumor is realized as follows:
c1, extracting tumors;
c2, generating a virtual square box body matched with the maximum length, width and height of the tumor, inlaying the tumor in the virtual square box body, and randomly generating spheres with the radius of 1cm (effective radiation range) in the virtual square box body, wherein one sphere is equivalent to a radioactive particle source;
c3, uniformly releasing rays from the center point to the periphery of the generated sphere with the radius of 1cm (effective radiation range), detecting whether each ray intersects with the surface of the tumor, if so, confirming that the sphere is positioned in the tumor, and is an effective sphere, keeping the sphere, otherwise, confirming that the sphere is not completely positioned in the tumor, and deleting the sphere until the number of the spheres reaches the total number of radioactive particle sources required by the tumor.
The radioactive particle source linear filling method in the tumor is realized as follows:
d1, extracting a tumor, wherein the tumor is a well-segmented tumor surface drawing model;
d2, taking an origin at the lower part of the tumor, generating a virtual cylinder by taking a Z axis passing through the origin as a central line, and generating spheres with the radius of 1cm (effective radiation range) at equal intervals on the central line of the overlapped section of the cylinder and the tumor, wherein one sphere is equivalent to a radioactive particle source;
d3, inclining m degrees from the central line to the X axis and rotating for a circle to form a virtual cone, selecting uniform I buses as the central lines to respectively form virtual cylinders, and generating spheres with the radius of 1cm (effective radiation range) at equal intervals on the central line of the overlapped section of the cylinder and the tumor;
d4, inclining m degrees from the central line to the X axis and rotating for a circle to form a virtual cone, selecting uniform I buses as the central lines to respectively form virtual cylinders, and generating spheres with the radius of 1cm (effective radiation range) at equal intervals on the central line of the overlapped section of the cylinder and the tumor;
d5, and d4 is executed circularly until the formed virtual vertebral body is stopped when not intersecting with the tumor;
d6, when stopping, counting the number of the generated spheres, comparing the number of the spheres with the total number of the radioactive particle sources required by the tumor, if the difference between the number of the spheres and the total number of the radioactive particle sources required by the tumor exceeds a set value, adjusting the degree of inclination towards the X axis and the number of generatrices on each virtual vertebral body, and executing d3-d6 in a circulating mode until the number of the spheres approaches to the total number of the radioactive particle sources required by the tumor.
The above I.noteq.P, m is generally 5.
The virtual cylinder is a cylinder or a square cylinder.
The total activity of the radioactive particle source required by the conventional tumor is obtained by a Paris formula (according to the average diameter length of the tumor body) or calculated according to the mass of the tumor body.
a. Paris's formula (based on mean diameter length of tumor mass).
The dose to be administered is calculated using the Dimension-averaging method:
A=Da*K
wherein A is total activity and is expressed in mCi; da is the average diameter length of tumor body, unit cm, Da is (length + width + height)/3; k is the fitting parameter and K value for iodine 125 is 5.
The specific calculation formula modified from the above paris formula is shown in table 1.
TABLE 1
Average diameter of tumor Da (cm) |
Total activity of particle source A (mCi) |
Da≤2.4 |
A=5(Da+1) |
2.4<Da≤3.24 |
A=3.87(Da+1)1.293 |
Da>3.24 |
A=2.76(Da+1)1.581 |
b. And calculating according to the tumor mass.
Total activity of radioactive source (mCi) required for the tumor, i.e. expected tissue absorbed dose (cGy) tumor weight (g)/182.
Note: the mass of the tumor body can be estimated by means of CT.
The method for calculating the total number of radioactive particle sources required by the tumor by the paris formula (according to the average diameter length of the tumor body) has the defect of large calculation error for the tumor with irregular shape, and needs manual adjustment operation. The calculation method for calculating the total number of radioactive particle sources required by the tumor according to the tumor mass is basically to calculate the tumor mass through CT, but the tumor density is uncertain and uneven, so that the defect of large calculation error exists. In both of the above calculation methods, the total activity of the radioactive particle source required by the two calculation methods does not take into account the organs and tissues endangered in the tumor, for example, in the case that the tumor encloses a part of the blood vessel, the blood vessel is a normal tissue in reality, and the radioactive particle source is not required, so that the total activity of the radioactive particle source required by the two calculation methods is greatly greater than the total activity of the radioactive particle source required by the covered blood vessel, that is, overdose, which is inaccurate in calculation and may cause great damage to the normal tissue.
The invention calculates the total number of radioactive particle sources needed by the tumor by the following method:
i1, simulating a radioactive particle source as a sphere with the radius of 1cm (effective radiation range) in a three-dimensional space, wherein the radioactive particle source is a capsule body, and the simulation is that the radioactive particle source (80% of the I125 particles cover the area with the radius of 1cm) covered by a certain dosage value is similar to the sphere, and only the simulation is a sphere with the radius of 1 cm;
i2, obtaining the tumor volume and the endangered organ and tissue volume in the tumor, and obtaining the actual filling volume by the formula (1):
actual fill volume-tumor volume of organs and tissues at risk (1);
i3, obtaining the total number of radioactive particle sources needed by the tumor by the formula (2):
the total number of radioactive particle sources needed by the tumor is equal to the actual filling volume/(4 pi/3) cm3(2)。
The above tumor volume was obtained by:
and a5, obtaining a well-segmented tumor surface drawing model, and calculating the tumor volume and the volume of organs and tissues endangered in the tumor.
The above tumor volume is obtained in another way:
b1, manually or computer drawing the tumor contour of each tomography image of the target part and the contour of organs and tissues at risk in the tumor body, and calculating the tumor area of each tomography image of the target part and the area of organs and tissues at risk in the tumor body;
b2, overlapping the tumor areas of each tomography of the target part, multiplying by the layer thickness to obtain the tumor volume, overlapping the organs and tissues at risk in the tumor of each tomography of the target part, and multiplying by the layer thickness to obtain the organs and tissues at risk in the tumor.
The method for calculating the total number of the radioactive particle sources required by the tumor is more accurate in calculation for the tumor with irregular shape, the calculated total activity of the required radioactive particle sources is closer to the actual total activity of the required radioactive particle sources, damage to normal tissue is reduced to the maximum extent, and the calculated total number of the radioactive particle sources required by the tumor can be used as a switching threshold value of later-stage radioactive particle source distribution.
The method for filling the radioactive particle source further includes: radioactive particle source treatment of organs and tissues within a tumor.
Radioactive particle source treatment of organs and tissues at risk in a tumor is realized by the following modes:
performing collision detection and distance measurement on a radioactive particle source generated in a tumor and organs and tissues endangered in the tumor, and if a central point of a certain radioactive particle source penetrates through the organs and tissues endangered in the tumor or the shortest distance between the central point of the certain radioactive particle source and the organs and tissues endangered in the tumor is smaller than a set value, regarding the radioactive particle source as an invalid radioactive particle source, and deleting the radioactive particle source; otherwise, the radioactive particle source is effectively radioactive particle source and is reserved.
The above setting is generally 1 cm.
After the radioactive particle source linear horizontal arrangement and radioactive particle source free arrangement steps, radioactive particle source treatment of organs and tissues endangered in the tumor is also carried out:
performing collision detection and distance measurement on the arranged radioactive particle sources and organs and tissues endangered in the tumor body, and if the central point of a certain radioactive particle source penetrates through the organs and tissues endangered in the tumor body or the shortest distance between the central point of a certain radioactive particle source and the organs and tissues endangered in the tumor body is smaller than a set value, regarding the radioactive particle source as an invalid radioactive particle source, and deleting the radioactive particle source; otherwise, the radioactive particle source is effectively radioactive particle source and is reserved.
On the basis of the above technical solution, the present embodiment further includes coordinate transformation:
finding a corresponding point in a tomography map according to the isocenter of the automatic equipment, solving the coordinate information of each needle track and the delta X and delta Y values of the isocenter, the rotation angle value and the inclination angle value in a three-dimensional space, and transmitting the coordinate information and the rotation angle value to the automatic equipment so as to enable the automatic equipment to operate according to the planned needle track.
On the basis of the above technical solution, the present embodiment further includes calculating, drawing, etc. a dose curve and calculating and drawing a DVH map (dose volume histogram) for the point dose in the tumor after the radioactive particle source distribution step in the tumor.
The specific implementation of calculating the tumor intrabody spot dose is as follows, as shown in fig. 2:
z1011, calculating the tumor body internal point dose by using the formula (3):
wherein S iskAir kerma intensity (air kerma length), meaning the air kerma rate in vacuum caused by photons with energy greater than delta in air of an infinitesimal volume at a distance much greater than the size of the source itselfThe product of the distance d squared, i.e., equation (4):
wherein G isr(r,θ)=r-2Point source fitting.
Wherein,and (6) fitting a line source.
Wherein Λ is a dose rate constant, which represents the dose rate caused by the source of the unit air kerma intensity at the reference point in the liquid water, and is expressed by the formula (5):
the value: 0.986 or 0.88 or 0.965.
The radial dose function (modified by inverse square law) is as follows:
gx(r)=a0+a1r+a2r2+a3r3+a4r4+a5r5(6)
wherein, a0=1.08;a1=0.9707;a2=0.02957;a3=0.1429;a4=-0.02256; a50.003117. The fitted correlation coefficient was 0.9999 and the sum of squared deviations was 2.78 x 10-4. The formula is applicable to r being 0.1-10.0 cm.
The anisotropy function (describing the effect of angle θ on the dose distribution) is given by equation (7):
F(r,θ)=a+bθ+cln r+dθ2+eln2r+fθln r+gθ3+hln3r+iθln2r+jθ2ln r (7)
wherein a is 0.2635; 1.4991; c is 0.1632; d is-1.005; -0.0284; -0.3150; 0.2224; h is 0.0202; i is 0.00155; and j is 0.1322.
Note that θ in the formula (7) is expressed in an arc value. The above fitting correlation coefficient R2=0.9926。
Sk value: (0.36-1.27).
Table 3 iodine 125 particle source activity results
As can be seen from table 3, there are particle sources with a relative error of 13.4% that exceed the relative deviation limit of ± 5%, which would be overdose if this batch of particle sources were used for clinical treatment.
The specific implementation manner of drawing the equal dosage curve is as follows:
z1021, divide the tumor into multiple 1 x 1mm3Calculating the superposed activity of the radioactive particle sources, averaging the dose values, taking the calculated average value as the dose value in the block, and taking the center point of the block as an expression point of the point dose;
z1022, connecting the centers of a plurality of squares with the same dosage value on the same horizontal plane to form a closed ring to form an equal dosage curve;
and Z1023, connecting the isodose curves of a plurality of isodose values in a three-dimensional space to form an isodose body.
A specific implementation of the DVH plot (dose volume histogram) was calculated and plotted: and (4) measuring the proportion of the volume covered by a certain dose value to the total volume of the tumor body according to the equal dose curve, thereby drawing a DVH (digital video recorder) graph.
The invention is not limited to the above alternative embodiments, and any other various forms of products can be obtained by anyone in the light of the present invention, but any changes in shape or structure thereof, which fall within the scope of the present invention as defined in the claims, fall within the scope of the present invention.