CN108671419A - A kind of calculating of quick afterloading radiotherapy dosage, verification method - Google Patents

Abstract

The invention discloses a kind of calculating of quick afterloading radiotherapy dosage, verification methods, and the corresponding DICOM file of patient is exported from treatment planning systems, are saved in a glue file folder；Glue file folder is scanned, required Rapid Dose Calculation information is read from DICOM file；Radioactive source parameter is obtained, Distribution of dose rate table is established, determines radioactive source direction, and carry out Rapid Dose Calculation；Dose Results in the Dose Results and treatment planning systems of calculating are compared, deviation Dev and γ verification result is obtained；After the completion of comparison, by deviation Dev and γ verification result preserve to glue file press from both sides in, and be automatically deleted glue file folder in DICOM file.The present invention can carry out dosage verifying before the treatment, simply, quickly, improve accuracy and efficiency, entire verification process only needs a few minutes, too many human-computer interaction is not needed, and can be used for various Afterloading radiotherapy planning systems, quality control and guarantee to Afterloading radiotherapy are improved, suitable for promoting.

Description

A Calculation and Verification Method of Rapid Afterloading Radiotherapy Dose

technical field

The invention relates to the technical field of backloading radiation therapy, in particular to a method for calculating and verifying fast afterloading radiation therapy doses.

Background technique

Backloading radiation therapy is an effective method of cancer treatment, evaluating the accuracy of dose calculation is crucial to ensure accurate afterloading radiation therapy; the process of radiation therapy is to dose the treatment plan after the treatment plan is approved and before the implementation begins verify.

After foreign physicists or dosimetrists complete the treatment plan design through the Treatment Planning System (TPS) (the treatment planning system is the existing software used by physicists or dosimetrists to design radiation therapy plans for patients), there are usually additional An experienced physicist performs dose verification of the treatment plan, but physicists in my country have heavy clinical tasks, and it is difficult to rely on another physicist to verify the dose of the treatment plan. The European Association of Radiation Therapy recommended that each afterloading radiotherapy center should have a dose verification method independent of the treatment planning system as early as 2004, but there is no research on the dose verification method of afterloading radiotherapy in my country.

Contents of the invention

Based on this, in view of the above problems, it is necessary to propose a rapid afterloading radiotherapy dose calculation and verification method that simplifies the afterloading radiotherapy process, improves the speed of dose calculation and verification, and ensures the accuracy of afterloading radiotherapy.

Technical scheme of the present invention is:

A method for calculating and verifying the dose of fast afterloading radiotherapy, comprising the following steps:

a. Export the DICOM file corresponding to the patient from the treatment planning system and save it in a fixed folder;

b. Scan the fixed folder and read the required dose calculation information from the DICOM file;

c. Obtain radioactive source parameters and establish a dose rate distribution table;

d. Determine the direction of the radiation source, perform dose calculation according to the dose calculation information, and obtain the dose calculation result;

e. Compare the obtained dose calculation result with the dose result in the treatment planning system to obtain the deviation value Dev and γ verification results;

f. After the comparison is completed, the deviation value Dev and γ verification results are saved to a fixed folder, and the DICOM files in the fixed folder are automatically deleted.

In this technical solution, from the perspective of a physicist or a dosimetrist, automatic processing is possible as much as possible, reducing manual intervention and saving time; through the calculation results of the treatment planning system (Treatment Planning System, TPS) and the technical solution Relatively independent calculation results are compared to obtain the deviation value Dev and γ verification results, and then judge whether the dose is reasonable according to the deviation value Dev and γ verification results, so as to avoid medical accidents; After time and time, the three-dimensional dose distribution can be automatically calculated. By comparing the dose distribution read in the treatment planning system with the dose distribution calculated by this technical solution, errors that are usually not easy to be found can be detected, such as the radiation source parameter database. Accidental change or damage, calibration date and activity input errors after radioactive source replacement, etc., to ensure safety; moreover, after the comparison is completed, this technical solution will automatically output the results to the file named by the user for future verification. And automatically delete the DICOM (Digital Imaging and Communications in Medicine) files (that is, the standard format files of medical images) in the fixed folder to avoid large memory burden and data errors caused by data redundancy.

Preferably, in the step c, the radioactive source parameters are obtained according to the data recommended by AAPM and ESTRO. In order to ensure the independence of the dose calculation of the software, the radiation source parameters are not obtained from the radiotherapy planning system, but the data recommended by AAPM (American Association of Physicists in Medicine) and ESTRO (European Society for Radiotherapy and Oncology) are used.

Preferably, establishing a dose rate distribution table in the step c includes the following steps:

Calculate the dose rate at a certain dose calculation point in, is the dose rate at the dose calculation point, r is the distance from the dose calculation point to the center of the radioactive source, r ₀ =1cm, θ is the angle between the dose calculation point and the long axis V direction of the radioactive source in the polar coordinate system, θ ₀ =π/2, S _k is the air kerma intensity, Λ is the dose rate constant, G is the geometry factor, g is the radial dose function, and F is the anisotropy function;

According to the symmetry of the dose distribution around the radioactive source, calculate the two-dimensional dose rate distribution table T(m, n) along the long axis V direction of the radioactive source and perpendicular to the long axis U direction of the radioactive source, and store it in the computer memory.

In this technical solution, the dose rate at a certain dose calculation point is calculated according to the formula recommended by the AAPM TG-43 (Task Group 43) report The formula recommended by the AAPM TG-43 (Task Group 43) report is a formula routinely used in the art, according to which the calculated dose rate The dose of the treatment planning system can be obtained, which is convenient for subsequent dose comparison; moreover, in order to improve the speed of dose calculation under the premise of ensuring the accuracy of dose calculation, combined with the symmetry of the dose distribution around the radioactive source, before starting the dose calculation, we first Calculate a two-dimensional dose rate distribution table T(m, n) along the long axis direction of the radioactive source (V direction) and perpendicular to the long axis direction of the radioactive source (U direction) and store it in the computer memory, wherein the dose rate The resolution of the distribution table in both the U direction and the V direction is 0.1 cm, the range of the U direction is 20 cm, and the range of the V direction is from -20 cm to 20 cm.

Preferably, determining the direction of the radioactive source in step d includes the following steps:

Set the i-th dwell position of the radioactive source as S _i ( _xi , y _i , _zi ), and pass through the dwell position S _i ( _xi , y _i , _zi ) and the next dwell position S A vector consisting of _i+1 (x _i+1 , y _i+1 , z _i+1 ) Determine the direction of the radioactive source in the human body coordinate system, and the vector Since the radiation source used is a line source, the line source needs to consider the difference between the radiation source coordinate system and the human body coordinate system. Therefore, the direction of the radiation source in the human body coordinate system is calculated to facilitate subsequent dose calculations.

Preferably, before performing dose calculation in step d, the dose calculation point is set as P(x, y, z), the total number of source applicator pipelines is N _A , and the residence position of the radioactive source in each source applicator pipeline is The total number is N _S , the contribution of the i-th residence position in the j-th applicator pipeline to the dose rate at P(x, y, z) is d _j,i , and the i-th residence position in the j-th applicator pipeline The dwell time of the i dwell positions is t _j,i . Preparation for dose calculation, based on the dose calculation information read from the exported DICOM file, makes it the same as the data in the treatment planning system, and calculates the dose results at the same dose calculation point, making the calculation more accurate and convenient for subsequent comparisons right.

Preferably, the dose calculation at P(x, y, z) in the step d includes the following steps:

d101. Calculate the distance r′ between P(x, y, z) and the _i -th residence position S _i ( _xi , y, _zi ) of the radioactive source, then

d102, according to the vector Calculated and angle between

d103. Calculate the distance v in the V direction and the distance u in the U direction from P(x, y, z) to the i-th residence position S _i ( _xi , y _i , z _i ) of the radioactive source, where v= r' cos θ,

d104. Check the dose rate distribution table T(m, n), if m×0.1cm≤u<(m+1)×0.1cm and n×0.1cm≤v<(n+1)×0.1cm, then for d The dose rate distribution corresponding to _{j, i} (u, v) is calculated by bilinear interpolation, and d _{j, i} (u, v)=w ₁ T(m, n)+w ₂ T(m, n+1 )+w ₃ T(m+1,n)+w ₄ T(m+1,n+1)

, where w ₁ , w ₂ , w ₃ and w ₄ are T(m,n), T(m,n+1), T(m+1,n) and T(m+ 1, the weight at n+1);

d105. Calculate the dose D(x, y, z) at P(x, y, z),

In this technical solution, each radioactive source contributes d _{j, i} (u, v) to the dose rate at P(x, y, z) by simply interpolating the data extracted from the memory without using AAPM The formula recommended by the TG-43 (Task Group 43) report is used for repeated calculations; the dose calculation grid size of this scheme is consistent with that of the treatment planning system, both are 0.1×0.1×0.1cm ³ , taking into account the dose within 0.5cm around the radioactive source are very high, and this part of the area is not the focus of clinical dose attention, so it is assumed that the dose within 0.5 cm from the radiation source is equal to the dose at 0.5 cm from the radiation source; thus, while ensuring the calculation accuracy, the calculation speed is improved.

Preferably, calculating the deviation value Dev in the step e includes the following steps:

e101. Obtain the dosimetry parameter D _TPS from the RT Dose of the treatment planning system;

e102. Obtain the dosimetry parameter D _QA after dose calculation;

e103. Calculate the deviation value Dev according to the dosimetry parameter D _TPS and the dosimetry parameter D _QA , and obtain

In this technical scheme, the dose distribution calculated by the treatment planning system is read from RT Dose, and compared with the dose distribution calculated by this scheme, we define D _x% as the radiation dose received by the volume of x% of the organ, D _ycc is the irradiation dose received by the volume of organ y cm ³ , according to the recommendation of ESTRO, statistics target area D _100% , D _90% , normal organs D _0.1cc , D _1cc and D _2cc ; thus, the dosimetric parameters D _QA and dose are calculated respectively The scientific parameter D _QA , and then calculate the deviation value Dev according to the comparison; this method can quickly evaluate the accuracy of afterload dose calculation and ensure the accuracy of afterload radiation therapy.

Preferably, the gamma verification in the step e includes the following steps:

e101. Read the dose from the RT Dose of the treatment planning system;

e102. Calculate the gamma value based on the calculated dose as the standard;

e103. If the γ value is greater than 1, the dose verification will not be passed; if the γ value is less than or equal to 1, the dose verification will be passed.

The γ verification is another verification method, which is a conventional verification method, and the calculation method of the γ value can be found in the literature (Low D A, Harms W B, Mutic S, et al. A technique for the quantitative evaluation of dose distributions[J].Medical Physics,1998,25(5):656-661.), mainly use the dose calculated by this program as a standard to compare with the dose read in the treatment planning system RT Dose (the file storing the dose in the DICOM file) , to judge whether the verification is passed; the accuracy of the dose can be judged not only according to the deviation value Dev, but also according to the γ verification, so as to ensure the accuracy of afterloading radiation therapy, further improve safety, and avoid medical accidents.

The beneficial effects of the present invention are:

The present invention provides a simple and fast post-installation dose verification tool capable of performing dose verification before treatment, which improves the accuracy and efficiency of verification. The entire verification process only takes a few minutes, reduces the waiting time of patients, and does not require much Human-computer interaction saves time and labor costs, and can be used in various after-installation radiation therapy planning systems, which strengthens and promotes the quality control and quality assurance of after-installation radiation therapy, and greatly reduces the incidence of medical accidents , suitable for promotion and very valuable.

Description of drawings

Fig. 1 is the flow chart of the calculation and verification method of fast afterloading radiotherapy dose described in the embodiment of the present invention;

Fig. 2 is a schematic diagram of a dose calculation coordinate system according to an embodiment of the present invention;

Fig. 3 is a schematic diagram of the differences in dosimetry parameters between the treatment planning system and this scheme for CTV in the case of D _100% according to the embodiment of the present invention;

Fig. 4 is a schematic diagram of the difference in dosimetry parameters between the treatment planning system and the program under the condition of D _90% for CTV according to the embodiment of the present invention;

Fig. 5 is a schematic diagram of the differences in dosimetry parameters between the treatment planning system and this program for the bladder in the case of D _0.1cc according to the embodiment of the present invention;

Fig. 6 is a schematic diagram of the differences in dosimetric parameters between the treatment planning system and the present scheme for the bladder under the condition of D _1cc according to the embodiment of the present invention;

Fig. 7 is a schematic diagram of the differences in dosimetric parameters between the treatment planning system and this program for the bladder in the case of D _2cc according to the embodiment of the present invention;

Fig. 8 is a schematic diagram of the difference in dosimetry parameters between the treatment planning system and this scheme for the rectum in the case of D _0.1cc according to the embodiment of the present invention;

Fig. 9 is a schematic diagram of the difference in dosimetric parameters between the treatment planning system and this scheme for the rectum in the case of D _1cc according to the embodiment of the present invention;

Fig. 10 is a schematic diagram of the difference in dosimetry parameters between the treatment planning system and this scheme for the rectum in the case of D _2cc according to the embodiment of the present invention;

Fig. 11 is a schematic diagram of the difference in dosimetric parameters between the treatment planning system and this program for the small intestine in the case of D _0.1cc according to the embodiment of the present invention;

Fig. 12 is a schematic diagram of the difference in dosimetric parameters between the treatment planning system and this scheme for the small intestine in the case of D _1cc according to the embodiment of the present invention;

Fig. 13 is a schematic diagram of the differences in dosimetric parameters between the treatment planning system and this scheme for the small intestine in the case of D _2cc according to the embodiment of the present invention;

Fig. 14 is a flow chart of performing gamma verification according to the embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Example 1

As shown in Figure 1, a method for calculating and verifying the dose of fast afterloading radiotherapy includes the following steps:

a. Export the DICOM file corresponding to the patient from the treatment planning system and save it in a fixed folder;

b. Scan the fixed folder and read the required dose calculation information from the DICOM file;

c. Obtain radioactive source parameters and establish a dose rate distribution table;

d. Determine the direction of the radiation source, perform dose calculation according to the dose calculation information, and obtain the dose calculation result;

e. Compare the obtained dose calculation result with the dose result in the treatment planning system to obtain the deviation value Dev and γ verification results;

f. After the comparison is completed, the deviation value Dev and γ verification results are saved to a fixed folder, and the DICOM files in the fixed folder are automatically deleted.

In this embodiment, from the point of view of a physicist or a dosimetrist, automatic processing is possible as much as possible, which reduces manual intervention and saves time; Relatively independent calculation results are compared to obtain the deviation value Dev and γ verification results, and then judge whether the dose is reasonable according to the deviation value Dev and γ verification results, so as to avoid medical accidents; in this embodiment, the residence position of the radioactive source in the treatment planning system is imported After time and time, the three-dimensional dose distribution can be automatically calculated. By comparing the dose distribution read in the treatment planning system with the dose distribution calculated by this technical solution, errors that are usually not easy to be found can be detected, such as the radiation source parameter database. Accidental change or damage, incorrect calibration date and activity input after radioactive source replacement, etc., thereby ensuring safety; moreover, after the comparison is completed, this embodiment will automatically output the results to a file named by the user for future verification, and Automatically delete DICOM (Digital Imaging and Communications in Medicine) files in fixed folders to avoid large memory burden and data errors caused by data redundancy.

Example 2

In this embodiment, on the basis of Embodiment 1, in the step c, the radioactive source parameters are acquired according to the data recommended by AAPM and ESTRO. In order to ensure the independence of the dose calculation of the software, the radiation source parameters are not obtained from the radiotherapy planning system, but the data recommended by AAPM (American Association of Physicists in Medicine) and ESTRO (European Society for Radiotherapy and Oncology) are used.

Example 3

In this embodiment, on the basis of Embodiment 2, establishing a dose rate distribution table in the step c includes the following steps:

Calculate the dose rate at a certain dose calculation point in, is the dose rate at the dose calculation point, r is the distance from the dose calculation point to the center of the radioactive source, r ₀ =1cm, θ is the angle between the dose calculation point and the long axis V direction of the radioactive source in the polar coordinate system, θ ₀ =π/2, S _k is the air kerma intensity, Λ is the dose rate constant, G is the geometry factor, g is the radial dose function, and F is the anisotropy function;

According to the symmetry of the dose distribution around the radioactive source, calculate the two-dimensional dose rate distribution table T(m, n) along the long axis V direction of the radioactive source and perpendicular to the long axis U direction of the radioactive source, and store it in the computer memory.

In this embodiment, the dose rate at a certain dose calculation point is calculated according to the formula recommended by the AAPM TG-43 (Task Group 43) report The formula recommended by the AAPM TG-43 (Task Group 43) report is a formula routinely used in the art, according to which the calculated dose rate The dose of the treatment planning system can be obtained, which is convenient for subsequent dose comparison; moreover, in order to improve the speed of dose calculation under the premise of ensuring the accuracy of dose calculation, combined with the symmetry of the dose distribution around the radioactive source, before starting the dose calculation, we first Calculate a two-dimensional dose rate distribution table T(m, n) along the long axis direction of the radioactive source (V direction) and perpendicular to the long axis direction of the radioactive source (U direction) and store it in the computer memory, wherein the dose rate The resolution of the distribution table in both the U direction and the V direction is 0.1 cm, the range of the U direction is 20 cm, and the range of the V direction is from -20 cm to 20 cm.

Example 4

This embodiment is based on Embodiment 2, as shown in Figure 2, determining the direction of the radioactive source in the step d includes the following steps:

Set the i-th dwell position of the radioactive source as S _i ( _xi , y _i , _zi ), and pass through the dwell position S _i ( _xi , y _i , _zi ) and the next dwell position S A vector consisting of _i+1 (x _i+1 , y _i+1 , z _i+1 ) Determine the direction of the radioactive source in the human body coordinate system, and the vector Since the radiation source used is a line source, the line source needs to consider the difference between the radiation source coordinate system and the human body coordinate system. Therefore, the direction of the radiation source in the human body coordinate system is calculated to facilitate subsequent dose calculations.

Example 5

In this embodiment, on the basis of Example 1, before the dose calculation in step d, the dose calculation point P(x, y, z) is set, the total number of applicator pipelines is N _A , and each applicator The total number of residence positions of radioactive sources in the pipeline is N _S , and the contribution of the i-th residence position in the j-th source applicator pipeline to the dose rate at P(x, y, z) is d _{j, i} , and the j-th root The dwell time of the ith dwell position in the applicator pipeline is t _j,i .

Example 6

In this embodiment, on the basis of Example 4, before the dose calculation in step d, the dose calculation point P(x, y, z) is set, the total number of applicator pipelines is N _A , and each applicator The total number of residence positions of radioactive sources in the pipeline is N _S , and the contribution of the i-th residence position in the j-th source applicator pipeline to the dose rate at P(x, y, z) is d _{j, i} , and the j-th root The dwell time of the ith dwell position in the applicator pipeline is t _j,i .

Preparation for dose calculation, based on the dose calculation information read from the exported DICOM file, makes it the same as the data in the treatment planning system, and calculates the dose results at the same dose calculation point, making the calculation more accurate and convenient for subsequent comparisons right.

Example 7

In this embodiment, on the basis of Embodiment 6, the dose calculation at P(x, y, z) in the step d includes the following steps:

d101. Calculate the distance r′ between P(x, y, z) and the _i -th residence position S _i ( _xi , y, _zi ) of the radioactive source, then

d102, according to the vector Calculated and angle between

d103. Calculate the distance v in the V direction and the distance u in the U direction from P(x, y, z) to the i-th residence position S _i ( _xi , y _i , z _i ) of the radioactive source, where v= r' cos θ,

d104. Check the dose rate distribution table T(m, n), if m×0.1cm≤u<(m+1)×0.1cm and n×0.1cm≤v<(n+1)×0.1cm, then for d The dose distribution corresponding to _{j, i} (u, v) is calculated by bilinear implantation, and d _{j, i} (u, v)=w ₁ T(m, n)+w ₂ T(m, n+1 )+w ₃ T(m+1,n)+w ₄ T(m+1,n+1)

, where w ₁ , w ₂ , w ₃ and w ₄ are T(m,n), T(m,n+1), T(m+1,n) and T(m+ 1, the weight at n+1);

d105. Calculate the dose D(x, y, z) at P(x, y, z),

In this embodiment, the contribution d _j,i (u, v) of each radioactive source to the dose rate at P(x, y, z) is obtained by simple interpolation of the data extracted from the internal memory, without the need for treatment The formulas in the planning system are recalculated; the dose calculation grid size of this plan is consistent with that of the treatment planning system, which is 0.1×0.1×0.1cm ³ . Considering that the dose in the 0.5cm range around the radioactive source is very high, this part of the area It is not the focus of clinical dose, so it is assumed that the dose within 0.5cm from the radiation source is equal to the dose at 0.5cm from the radiation source; thus, while ensuring the calculation accuracy, the calculation speed is improved.

Example 8

In this embodiment, on the basis of Embodiment 7, the calculation of the deviation value Dev in the step e includes the following steps:

e101. Obtain the dosimetry parameter D _TPS from the RT Dose of the treatment planning system;

e102. Obtain the dosimetry parameter D _QA after dose calculation;

e103. Calculate the deviation value Dev according to the dosimetry parameter D _TPS and the dosimetry parameter D _QA , and obtain

In this embodiment, the dose distribution calculated by the treatment planning system is read from RT Dose, and compared with the dose distribution calculated by this scheme, we define D _x% as the radiation dose received by the volume of x% of the organ, D _ycc is the irradiation dose received by the volume of the organ y cm ³ , according to the recommendations of ESTRO, count the target area D _100% , D _90% , and the normal organs D _0.1cc , D _1cc and D _2cc ; thus, the dosimetric parameters D _QA and dose are calculated respectively The scientific parameter D _QA , and then calculate the deviation value Dev according to the comparison; this method can quickly evaluate the accuracy of afterload dose calculation and ensure the accuracy of afterload radiation therapy;

For CTV (tumor clinical target area), the dosimetry parameter difference of treatment planning system and the present invention scheme is shown in Fig. 3 and Fig. 4, and Fig. 2 is the difference value of D _100% , and wherein maximum value is 1.76%, and minimum value is 0.08 %, the average difference of 20 patients is 0.85%; Fig. 3 is the difference value of D _90% , wherein the maximum value is 1.37%, the minimum value is 0.15%, the average difference of 20 patients is 0.70%;

For organs at risk, the differences in dosimetry parameters between the treatment planning system and the present invention’s scheme are shown in Figure 5-Figure 13, and 20 patients were selected, and the maximum deviation of bladder and small intestine D _0.1cc was less than 1.10%, and the maximum deviation of rectum D _0.1cc was less than 1.10%. The average difference of D _1cc in bladder, rectum and small intestine was 0.49%, 0.66% and 0.52%, respectively, and the difference in D _2cc was smaller than D _1cc and D _0.1cc .

Example 9

This embodiment is based on Embodiment 7, as shown in Figure 14, the gamma verification in the step e includes the following steps:

e101. Read the dose from the RT Dose of the treatment planning system;

e102. Calculate the gamma value based on the calculated dose as the standard;

e103. If the γ value is greater than 1, the dose verification will not be passed; if the γ value is less than or equal to 1, the dose verification will be passed.

The γ verification is another verification method, which is a conventional verification method, and the calculation method of the γ value can be found in the literature (Low D A, Harms W B, Mutic S, et al. A technique for the quantitative evaluation of dose distributions[J].Medical Physics,1998,25(5):656-661.), mainly use the dose calculated by this program as a standard to compare with the dose read in the treatment planning system RT Dose (the file storing the dose in the DICOM file) , to judge whether the verification is passed; the accuracy of the dose can be judged not only according to the deviation value Dev, but also according to the γ verification, so as to ensure the accuracy of afterloading radiation therapy, further improve safety, and avoid medical accidents.

The above-mentioned embodiments only express the specific implementation manner of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims (8)

1. A calculation and verification method of fast afterloading radiotherapy dose, is characterized in that, comprises the following steps: a. Export the DICOM file corresponding to the patient from the treatment planning system and save it in a fixed folder; b. Scan the fixed folder and read the required dose calculation information from the DICOM file; c. Obtain radioactive source parameters and establish a dose rate distribution table; d. Determine the direction of the radiation source, perform dose calculation according to the dose calculation information, and obtain the dose calculation result; e. Compare the obtained dose calculation result with the dose result in the treatment planning system to obtain the deviation value Dev and γ verification results; f. After the comparison is completed, the deviation value Dev and γ verification results are saved to a fixed folder, and the DICOM files in the fixed folder are automatically deleted. 2. The method for calculating and verifying the dose of fast afterloading radiotherapy according to claim 1, characterized in that, in the step c, the parameters of the radioactive source are obtained according to the data recommended by AAPM and ESTRO. 3. according to claim 1 or 2 described fast afterloading radiotherapy dose calculation, verification method, it is characterized in that, setting up dose rate distribution table in the described step c comprises the following steps: Calculate the dose rate at a certain dose calculation point in, is the dose rate at the dose calculation point, r is the distance from the dose calculation point to the center of the radiation source, r ₀ =1cm, θ is the angle between the dose calculation point and the long axis V direction of the radiation source in the polar coordinate system, θ0= π/2, S _k is the air kerma intensity, Λ is the dose rate constant, G is the geometry factor, g is the radial dose function, and F is the anisotropy function; According to the symmetry of the dose distribution around the radioactive source, calculate the two-dimensional dose rate distribution table T(m, n) along the long axis V direction of the radioactive source and perpendicular to the long axis U direction of the radioactive source, and store it in the computer memory. 4. The calculation and verification method of fast afterloading radiotherapy dose according to claim 1, characterized in that, determining the direction of the radiation source in the step d comprises the following steps: Set the i-th dwell position S _i ( _xi , y _i , _zi ) of the radioactive source, and pass the dwell position S _i ( _xi , y _i , _zi ) and the next dwell position S _{i +1} (x _i+1 , y _i+1 , z _i+1 ) vector Determine the direction of the radioactive source in the human body coordinate system, and the vector 5. according to claim 1 or 4 described fast afterloading radiotherapy dose calculation, verification method, it is characterized in that, before carrying out dose calculation in described step d, set dose calculation point as P(x, y, z ), the total number of source applicator pipes is N _A , the total number of radioactive source residence positions in each applicator pipe is N _S , and the i-th residence position pair P(x, y, The dose rate contribution at z) is d _j,i , and the dwell time of the i-th dwell position in the j-th applicator pipe is t _j,i . 6. The calculation and verification method of fast afterloading radiotherapy dose according to claim 5, characterized in that, in said step d, the calculation of the dose at P (x, y, z) place comprises the following steps: d101. Calculate the distance r′ between P(x, y, z) and the _i -th residence position S _i ( _xi , y, _zi ) of the radioactive source, then d102, according to the vector Calculated and angle between d103. Calculate the distance v in the V direction and the distance u in the U direction from P(x, y, z) to the i-th residence position S _i ( _xi , y _i , z _i ) of the radioactive source, where v= r' cos θ, d104. Check the dose rate distribution table T(m, n), if m×0.1cm≤u<(m+1)×0.1cm and n×01cm≤v<(n+1)×0.1cm, then for d _{j , the dose rate distribution corresponding to i} (u, v) is bilinearly interpolated to obtain d _{j, i} (u, v)=w ₁ T(m, n)+w ₂ T(m, n+1) +w ₃ T(m+1,n)+w ₄ T(m+1,n+1), Among them, w ₁ , w ₂ , w ₃ and w ₄ are T(m,n), T(m,n+1), T(m+1,n) and T(m+1 , the weight at n+1); d105. Calculate the dose D(x, y, z) at P(x, y, z), 7. The calculation and verification method of fast afterloading radiotherapy dose according to claim 6, is characterized in that, calculating deviation value Dev in the described step e comprises the following steps: e101. Obtain the dosimetry parameter D _TPS from the RT Dose of the treatment planning system; e102. Obtain the dosimetry parameter D _QA after dose calculation; e103. Calculate the deviation value Dev according to the dosimetry parameter D _TPS and the dosimetry parameter D _QA , and obtain 8. The calculation and verification method of fast afterloading radiotherapy dose according to claim 6, characterized in that, the gamma verification in the step e comprises the following steps: e101. Read the dose from the RT Dose of the treatment planning system; e102. Calculate the gamma value based on the calculated dose as the standard; e103. If the γ value is greater than 1, the dose verification will not be passed; if the γ value is less than or equal to 1, the dose verification will be passed.