A method for whole-body electronic in-vivo dosimetry based on a wash-off film

Abstract

The application provides a whole-body electronic linear in-vivo dose measurement method based on a self-developed film, which comprises the following steps: calculating the MU of a photon beam by a formula n , corresponding to the water absorbed dose D W,Q , then scanning and analyzing the to-be-calibrated films A1, A2...A m , obtaining the film pixel dose calibration curve, finally scanning and analyzing the pixel of the irradiated sample film B1, B2...B m , and obtaining the dose value of the sample film B1, B2...B m according to the film pixel dose calibration curve. The method is simple to implement, reliable in precision, and is helpful for the dose measurement before the whole-body electronic linear treatment and the in-vivo dose measurement during the treatment, and can effectively reduce the workload of the film batch processing of the physicist and increase the accuracy of the film dose analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radiation dose measurement, in particular to a whole-body electron in-vivo dose measurement method based on a no-wash film. BACKGROUND

[0002] Mycosis fungoides (MF) is also known as mycosis fungoides, which is a malignant tumor originating from the skin lymphatic system. Mycosis fungoides is a T4 lymphocyte-derived epidermotropic cutaneous malignant lymphoma of unknown etiology, which is the most common pathological type of primary cutaneous lymphoma, is clinically rare, and has a slow disease progression. Clinically, the disease progression is divided into erythema stage, plaque stage and tumor stage, and the prognosis of patients in the tumor stage is poor.

[0003] Total skin electron beam therapy (TSEBT) is one of the important means for treating patients with tumor stage mycosis fungoides. The electron beam multi-angle irradiation first applied by the Stanford University School of Medicine in the United States is currently recognized as the standard treatment method for whole-body skin malignant lesions. At the same time, a number of studies have reported that total skin electron beam therapy has good efficacy in treating mycosis fungoides and has a long stable time. Multi-center studies have shown that the dosimetric parameters of total skin electron beam therapy technology are very different from those of conventional single-field irradiation. Therefore, sufficient clinical dosimetry measurement is required before total skin electron beam therapy.

[0004] Because the source-skin distance used in total skin electron beam therapy technology is much larger than that of conventional treatment technology, and the rotating gantry and multi-field irradiation techniques are adopted, the percentage depth dose, dose uniformity in the field, etc. need to be measured in detail. At present, the clinical dose measurement of total skin electron beam therapy is mostly measured by using a multi-channel dosimeter or a film method. However, the multi-channel dosimeter is expensive and difficult to popularize. The film method has a long measurement process, a large amount of work, and the results are greatly affected by subjective factors, making it difficult to ensure work efficiency and the accuracy of the measurement results. SUMMARY

[0005] Therefore, the present application provides a whole-body electron in-vivo dose measurement method based on a no-wash film. The present application can quickly complete the calibration of film dose and the measurement of in-vivo film dose, effectively reducing the uncertainty in the whole-body electron in-vivo dose measurement process, and effectively improving the speed of film image batch processing.

[0006] To achieve the above-mentioned purpose, the embodiment of the present application provides a whole-body electron in-vivo dose measurement method based on a no-wash film, comprising the following steps:

[0007] S1. According to the calibration requirements of the calibration film, the photon beam MU is calculated by formulan The corresponding dose D W,Q value;

[0008] S2. Cut and mark the orientation and sequence of the films to be calibrated. Under standard measurement conditions, irradiate each film under equal conditions to obtain films A1, A2...A... to be calibrated. m ;

[0009] S3. Mark and cut the sample films according to the directions in step S2, and mark their positions according to the location of the dummy human body to be measured, to obtain sample films B1, B2...B m ;

[0010] S4. Take the sample films B1, B2...B from step S3. m The sample films were fixed on the mannequin according to the marked positions, and then irradiated to obtain irradiated sample films B1, B2...B m ;

[0011] S5. Scan the films to be calibrated in step S2, A1, A2...Am, to obtain the average pixels of the red channel of films A1, A2...Am, and obtain the film pixel dose calibration curve through one analysis.

[0012] S6. Scan the sample films B1, B2...B1 irradiated in step S4. m Based on the film pixel dose calibration curve in step S5, the pixels of sample film B1, B2...B1 are obtained through secondary analysis. m The dosage value.

[0013] In step S1,

[0014] The formula is: D W,Q =M Q ·N D,W,Q0 ·K Q,Q0 ; where D W,Q It is the water absorption dose of a high-energy photon beam with a radiation quality of Q; M Q This refers to the dosimeter reading after calibration for temperature, air pressure, humidity, polarization effect, and ionization recombination effect, per megahertz (M). Q Each value has a corresponding MU value, i.e., MU n N D,W,Q0 It is the water absorbed dose calibration factor under standard radiation quality conditions; K Q,Q0 It refers to the radiation quality calibration factor of radiation quality Q when Q0 is used as the standard radiation quality;

[0015] The N D,W,Q0 According to the calibration certificates provided annually by the National Institute of Metrology of China, the K... Q,Q0According to the ray quality TPR 20 / 10 table lookup;

[0016] The MU n = 0, MU2 = 10, MU3 = 20, MU4 = 30, MU5 = 50, MU6 = 80, MU7 = 100, MU8 = 150, MU9 = 200, MU 10 = 250, MU 11 = 300, MU 12 = 400, MU 13 = 500, MU 14 = 600, MU 15 = 700, MU 16 = 800, MU 17 = 900, D W,Q = 1 ~ D 17 , respectively.

[0017] The measurement conditions used in step S1 require that the accelerator gantry angle is 0 degrees, the small head angle is 0 degrees, the field size is 10x10 cm 2 , and the measurement is obtained at a depth of 5 cm under an equivalent water phantom source skin distance SSD of 100 cm;

[0018] In step S2,

[0019] The standard measurement conditions are that the accelerator gantry angle is 0 degrees, the small head angle is 0 degrees, the field size is 10x10 cm 2 , the equivalent water phantom source skin distance SSD is 100 cm, and the depth is 5 cm;

[0020] In step S3,

[0021] The sample film and the film to be calibrated are the same batch of film and the same box of film, and the sample film and the film to be calibrated are the same size.

[0022] In step S5,

[0023] The scanning is realized by a film scanner; and the scanning needs to be completed at least 24 hours after irradiation;

[0024] The film pixel dose calibration curve is the relationship curve between the film pixels and the dose of the films A1, A2,..., A m ; and the calibration curve is a fitting curve.

[0025] In the one-time analysis, the red channel pixel value mean of the film image is obtained, and the film pixels are locked to the films A1, A2,..., A mThe effective area in the film is locked and the pixel mean value of the same area size is obtained as the calibration reference value in the film pixel dose calibration curve.

[0026] In step S6,

[0027] The scanning is realized by a film scanner.

[0028] The scanning conditions in step S5 and step S6 are the same, and the scanning needs to be completed at least 24 hours after irradiation.

[0029] The same scanning conditions include the same scanning parameters, the same position of the film in the scanner and the same scanning direction of the film.

[0030] In the secondary analysis, the sample films B1, B2,..., B m The effective area in the film is locked and the pixel mean value of the same area size is obtained as the calibration reference value in the film pixel dose calibration curve.

[0031] As a preferred embodiment, the primary analysis and the secondary analysis are realized in batch processing by codes.

[0032] The codes include two parts: the first part obtains the film pixel dose calibration curve by applying the connected domain method, and the second part realizes the reading of the measured film dose by applying the connected domain and the minimum difference method. The process of the codes in the application is mainly realized by the method, and the main method used in the codes is the minimum connected domain method and the minimum difference method, which realizes the calibration curve between the pixel and the dose and the subsequent acquisition of the dose of the measured film. The code realization of the two methods is not limited to a specific compiling environment.

[0033] The application selects corresponding measurement work under a medical linear accelerator. The film dose calibration before irradiation is carried out under the standard conditions that the accelerator treatment head zero degree, the collimator zero degree, the field size is 10*10cm 2 , the source skin distance SSD is 100cm, the measurement depth is 5cm; the film is fixed on the specific monitoring point of the phantom, the position SSD is 340cm, and the rotating multi-field irradiation simulation treatment is adopted. The codes are used for batch processing of images, and then the measurement and analysis of the in-vivo dose are realized.

[0034] The application realizes the measurement and analysis of the in-vivo dose by calculation.

[0035] B1, B2,..., B mThe data obtained by analyzing the films are all near the clinical prescription dose, and the errors are all within the acceptable range. The results prove that the method of the present application is feasible and can quickly batch process film dose.

[0036] The method of the present application is simple to implement, reliable in precision, and convenient for clinical application, and is helpful for dose verification before whole-body electron linear treatment and in-vivo dose verification during treatment. Thus, the workload of the physicist for film batch processing is reduced, and the accuracy of film dose analysis is increased. The present application solves the cumbersome problem of data batch processing in film-based whole-body electron linear dose measurement and analysis. Through code batch processing of data, the dose calibration of the film and the dose analysis of the measured film are simply and quickly completed, and the consistency of data processing reduces the human error of the physicist during data analysis. In addition, the above method is simple to implement, reliable in precision, and convenient for clinical application. For whole-body electron linear irradiation technology, it is convenient to complete multiple film dose analysis of multiple monitoring points during treatment, and the actual exposure of the patient's body surface during the actual exposure process can be accurately given. It has certain guiding significance for the treatment planner to design the patient's position in the treatment fraction and the position repeatability between fractions, and has very important reference value for the clinician to perfect the subsequent treatment plan.

[0037] Compared with the prior art, the whole-body electron linear in-vivo dose rapid verification method based on the film of the present application has the following advantages:

[0038] (1) The method reduces the large amount of repetitive work during film dose calibration and film dose analysis, and improves the efficiency of data analysis;

[0039] (2) The method reduces the accidental error in the data processing process of the physicist, and the data results are more objective and consistent;

[0040] (3) The method is simple and fast, and does not depend on existing film analysis software and specific code compilation environment. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0042] Figure 1 The flowchart of the implementation of the whole-body electron linear in-vivo dose measurement method based on the film of an embodiment of the present application is shown in the figure.

[0043] Figure 2Fig. 6 is a schematic view of marking points 36 on a dummy body according to another embodiment of the present application.

[0044] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments in combination with the accompanying drawings. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0046] The technical solutions among the various embodiments can be combined with each other, but it must be based on that a person of ordinary skill in the art can realize. When the combination of the technical solutions appears contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist, and is not within the protection scope of the present application.

[0047] In the present application, in order to solve the problems that the whole measurement process is time-consuming and labor-intensive in the prior art film method, and the result is greatly affected by subjective factors, and it is difficult to guarantee the work efficiency and the accuracy of the measurement result, a whole-body electron beam in-vivo dose measurement method based on a no-wash film is provided. The method can simply and quickly complete the dose calibration of the film and the measurement of the in-vivo dose, and provides dose monitoring and dose evaluation before treatment, in real time and at multiple points for whole-body electron beam irradiation, so as to provide dose basis for improving the treatment scheme in clinic. At the same time, the method can provide sufficient help for the measurement work of a physicist in the early stage and the treatment process, and can obviously improve the analysis efficiency of the film data.

[0048] Specifically, as shown in the figure, Figure 1 The present application provides a whole-body electron beam in-vivo dose measurement method based on a no-wash film, which comprises the following steps:

[0049] S1. According to the calibration requirement of the film, the photon beam MU is calculated by a formula. n The corresponding dose D W,Q value is calculated.

[0050] In step S1,

[0051] The formula is: D W,Q =M Q ·N D,W,Q0 ·K Q,Q0 ; wherein D W,Q is the water absorption dose of the high-energy photon beam with the ray quality Q; M QThis refers to the dosimeter reading after calibration for temperature, air pressure, humidity, polarization effect, and ionization recombination effect, per megahertz (M). Q Each value has a corresponding MU value, i.e., MU n N D,W,Q0 It is the water absorbed dose calibration factor under standard radiation quality conditions; K Q,Q0 It refers to the radiation quality calibration factor of radiation quality Q when Q0 is used as the standard radiation quality;

[0052] The N D,W,Q0 According to the calibration certificates provided annually by the National Institute of Metrology of China, the K... Q,Q0 Obtained from the table based on the radiation quality TPR20 / 10;

[0053] The MU n The values ​​are MU1=0, MU2=10, MU3=20, MU4=30, MU5=50, MU6=80, MU7=100, MU8=150, MU9=200, and MU... 10 =250, MU 11 =300, MU 12 =400, MU 13 =500, MU 14 =600, MU 15 =700, MU 16 =800, MU 17 When = 900, D W,Q Dose values ​​were obtained for D1 to D2 respectively. 17 ;

[0054] The measurement conditions required for step S1 are: accelerator frame angle 0 degrees, small head angle 0 degrees, and firing field size 10×10cm. 2 Measurements were taken at an equivalent water phantom body source skin distance of 100cm and a depth of 5cm.

[0055] S2. Cut and mark the orientation and sequence of the films to be calibrated. Under standard measurement conditions, irradiate each film under equal conditions to obtain films A1, A2...A... to be calibrated. m ;

[0056] In step S2,

[0057] The standard measurement conditions are: accelerator frame angle 0 degrees, small nose angle 0 degrees, and firing field size 10×10cm. 2 The equivalent water phantom body has a surface distance of 100cm from the surface of the SSD and a depth of 5cm.

[0058] S3, marking and cutting the sample film according to the direction in step S2, marking the position according to the position of the dummy body surface to be measured, to obtain sample films B1, B2, …, B m ;

[0059] In step S3,

[0060] The sample film and the film to be calibrated are the same batch of films, the same box of films, and the size of the sample film and the film to be calibrated is the same.

[0061] S4, scanning the sample films B1, B2, …, B m of step S3 according to the position mark on the dummy body, then irradiating, to obtain the irradiated sample films B1, B2, …, B m ;

[0062] S5, scanning the film to be calibrated A1, A2, …, Am of step S2 to obtain the red channel average pixel of the films A1, A2, …, Am, and obtaining the film pixel dose calibration curve through one analysis;

[0063] In step S5,

[0064] The scanning is realized by a film scanner; the scanning needs to be completed at least 24 hours after irradiation;

[0065] The film pixel dose calibration curve is a relationship curve between the film pixels of the film to be calibrated A1, A2, …, A m and the dose; the calibration curve is a fitting curve.

[0066] In the one analysis, the red channel pixel value mean of the film image is obtained, and in the analysis, the film pixels are locked in the effective area in the film to be calibrated A1, A2, …, A m and the pixel mean of the same area size is obtained as the calibration reference value in the film pixel dose calibration curve.

[0067] S6, scanning the pixels of the irradiated sample films B1, B2, …, B m of step S4, and obtaining the dose value of the sample films B1, B2, …, B m through secondary analysis according to the film pixel dose calibration curve in step S5.

[0068] In step S6,

[0069] The scanning is realized by a film scanner.

[0070] The scanning conditions in step S5 and step S6 are the same, and the scanning needs to be completed at least 24 hours after irradiation.

[0071] The same scanning conditions include the same scanning parameters, the same position of the film in the scanner and the same scanning direction of the film.

[0072] The secondary analysis locks the effective area of the sample film B1, B2,..., Bn by the connected domain method and obtains the red channel pixel mean value of the same area size as the measurement pixel value of the measurement area. m The film pixel dose calibration curve is obtained by applying the connected domain method, and the measurement film dose reading is realized by applying the connected domain and the minimum difference method.

[0073] As a preferred embodiment, the primary analysis and the secondary analysis are realized by batch processing through codes.

[0074] The code includes two parts: the first part obtains the film pixel dose calibration curve by applying the connected domain method, and the second part realizes the measurement film dose reading by applying the connected domain and the minimum difference method. The process of the code in the present application is mainly realized by the method, and the main method used in the code is the minimum connected domain method and the minimum difference method, which realizes the calibration curve between the pixel and the dose and the subsequent measurement of the film dose. The code implementation of the two methods is not limited to a specific compilation environment.

[0075] The present application selects corresponding measurement work under a medical linear accelerator. The film dose calibration is performed under the standard conditions of accelerator treatment head zero degree, collimator zero degree, field size 10*10cm 2 , source skin distance SSD 100cm, measurement depth 5cm, and radiation before film dose calibration; the film is fixed on the dummy phantom at specific monitoring points, the position SSD=340cm is arranged, and the rotating multi-field irradiation simulation treatment is adopted. The code is used for batch processing of images, and the measurement and analysis of in-vivo dose are obtained.

[0076] In one embodiment, a complete treatment process is simulated on the dummy phantom, and during the whole process, the mark point 36 is taken on the patient's body, and the position is as shown in a-f. Figure 2

[0077] After 24 hours of completing the dose irradiation, after scanning by the scanner, the above-mentioned 36 groups of irradiated film images are analyzed by the above-mentioned method, and the results are shown in Table 1.

[0078] Table 1. Dummy body surface film dose monitoring table

[0079]

[0080] ​The conclusion obtained by analysis is that: after one treatment, the dose received by the skin of the phantom does not fully meet the clinical prescription dose, the dose at positions such as positions with large body surface curvature, skin folds, and positions easy to block is obviously low, and in actual treatment, the body position of the patient should be as repeatable as possible. In addition, in the actual treatment process, the limbs should be opened as much as possible to avoid the non-uniformity of the dose caused by unnecessary blocking. These measurement results provide suggestions for the development of whole-body electron linear therapy in the clinic.

[0081] The results of the calculation measurement show that: B1, B2, B m The data obtained by analyzing the film are near the clinical prescription dose, and the errors are within the acceptable range. The results confirm that the calculation method of the application is feasible, can effectively improve the processing efficiency of data, and the measurement results provide effective suggestions for the clinic. The results confirm that the method of the application is feasible, and can quickly batch process film doses.

[0082] The method described in the application is simple to implement, reliable in precision, convenient for clinical application, and helps to carry out dose verification before whole-body electron linear therapy and in-body dose verification during treatment in the clinic. Thus, the workload of the physicist in film batch processing is reduced, and the accuracy of film dose analysis is increased. The application solves the tedious problem of data batch processing in whole-body electron linear dose measurement and analysis based on film. Through batch processing of data by code, the dose calibration of the film and the dose analysis of the measurement film are simply and quickly completed, and the consistency of data processing reduces the human error of the physicist in data analysis. In addition, the above-mentioned method is simple to implement, reliable in precision, and convenient for clinical application. For whole-body electron linear irradiation technology, it is convenient to complete multiple, multiple monitoring point film dose analysis during treatment, can accurately give the dose of the patient's body surface in the actual irradiation process, has certain guiding significance for the treatment designer to design the patient's body position in the treatment fraction and the body position repeatability between fractions, and has very important reference value for the clinician to perfect the subsequent treatment plan.

[0083] Compared with the prior art, the whole-body electron in-body dose rapid verification method based on the film of the application has the following advantages:

[0084] (1) The method reduces a large amount of repetitive work in film dose calibration and film dose analysis, and improves the efficiency of data analysis;

[0085] (2) The method reduces accidental errors in the data processing process of the physicist, and the data results are more objective and consistent;

[0086] (3) The method is simple and fast, and does not depend on existing film analysis software and specific code compilation environment.

[0087] The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural changes made according to the content of the present application specification and drawings, or direct / indirect application in other related technical fields, are included in the patent protection scope of the present application.

Claims

1. A method for measuring whole-body electron beam dosimetry based on washable film, characterized in that: Includes the following steps: S1. Calculate the photon beam MU using the formula according to the calibration requirements of the standard. n The corresponding dose D W,Q value; S2. Cut and mark the orientation and sequence of the films to be calibrated. Under standard measurement conditions, irradiate each film under equal conditions to obtain films A1, A2...A... to be calibrated. m ; S3. Mark and cut the sample films according to the directions in step S2, and mark their positions according to the location of the dummy human body to be measured, to obtain sample films B1, B2...B m ; S4. Take the sample films B1, B2...B from step S3. m The sample films were fixed on the mannequin according to the marked positions, and then irradiated to obtain irradiated sample films B1, B2...B m ; S5. Scan the calibration films A1, A2...A2 from step S2. m Obtain A1, A2...A m The average pixels of the red channel of the film are used to obtain the film pixel dose calibration curve through a single analysis; S6. Scan the sample films B1, B2...B1 irradiated in step S4. m The pixel values ​​of the sample film B1, B2...Bm are obtained through secondary analysis based on the film pixel dose calibration curve in step S5. In step S5, during the analysis, the average pixel value of the red channel of the film image is obtained. During the analysis, the film pixels are used to locate the films to be calibrated (A1, A2...A1) using a connected component method. m The effective area in the film is used to obtain the average pixel value of the same area size as the calibration reference value in the film pixel dose calibration curve; In step S6, the secondary analysis uses the connected component method to locate sample films B1, B2...B... m The effective area in the film is selected, and the average value of the red channel pixels of the same area size is obtained as the measurement pixel value of the measurement area. According to the film pixel dose calibration curve, the minimum difference method is used to read the amount of film to be measured. The primary and secondary analyses are implemented in batch processing via code. The code consists of two parts: the first part obtains the film pixel dose calibration curve by applying the connected component method, and the second part reads the film amount by applying the connected component and minimum difference method.

2. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 1, characterized in that: In step S1, the formula is: D W,Q =M Q ·N D,W,Q0 ·K Q,Q0 ; Among them, D W,Q It is the water absorption dose of a high-energy photon beam with a radiation quality of Q; M Q This refers to the dosimeter reading after calibration for temperature, air pressure, humidity, polarization effect, and ionization recombination effect, per megahertz (M). Q Each value has a corresponding MU value, i.e., MU n N D,W,Q0 It is the water absorbed dose calibration factor under standard radiation quality conditions; K Q,Q0 It refers to the radiation quality calibration factor of radiation quality Q when Q0 is used as the standard radiation quality; The N D,W,Q0 According to the calibration certificates provided annually by the National Institute of Metrology of China, the K... Q,Q0 Obtained from the table based on the radiation quality TPR20 / 10.

3. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 2, characterized in that: The MU n The values ​​are MU1=0, MU2=10, MU3=20, MU4=30, MU5=50, MU6=80, MU7=100, MU8=150, MU9=200, and MU... 10 =250, MU 11 =300, MU 12 =400, MU 13 =500, MU 14 =600, MU 15 =700, MU 16 =800, MU 17 When = 900, D W,Q Dose values ​​were obtained for D1 to D2 respectively. 17 ; The measurement conditions required for step S1 are: accelerator frame angle 0 degrees, small head angle 0 degrees, and firing field size 10×10cm. 2 Measurements were taken at an equivalent water phantom body with a skin-to-skin distance (SSD) of 100cm and a depth of 5cm.

4. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 1, characterized in that: In step S2, the standard measurement conditions are: accelerator frame angle 0 degrees, small head angle 0 degrees, and firing field size 10×10cm. 2 The equivalent water phantom body has a surface distance of 100cm from the SSD and a depth of 5cm.

5. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 1, characterized in that: In step S3, the sample film and the film to be calibrated are from the same batch of film and the same box of film, and the sample film and the film to be calibrated are the same size.

6. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 1, characterized in that: In step S5, the scanning is performed using a film scanner; the scanning must be completed at least 24 hours after irradiation.

7. The whole-body electron beam in vivo dose measurement method based on washable film according to claim 1, characterized in that: In step S5, the film pixel dose calibration curve is the film to be calibrated A1, A2...A m The relationship curve between film pixels and dose; the calibration curve is a fitting curve.

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