Brachytherapy dose distribution verification phantom and method

Abstract

The present application relates to a kind of brachytherapy dose distribution verification phantom and method, the verification phantom includes phantom applicator conduit, phantom water tank and mechanical arm, phantom water tank is equipped with radiation detector, mechanical arm drives phantom applicator conduit to move, so that phantom applicator conduit is positioned in phantom water tank relative to radiation detector.The method includes, according to the CT scanning information of in-vivo applicator conduit, calibrating reference reference point and conduit reference point;In verification phantom, specify reference positioning point and conduit positioning point;Mechanical arm drives phantom applicator conduit to move to verification position.The beneficial effects of the present application are: by obtaining the positioning data of applicator conduit in patient body, the information of internal irradiation after-loading plan is simulated to transplant into phantom water tank, and radiation dose is detected in specified position using radiation detector, which can realize the verification of after-loading plan setting and equipment execution precision, verify irradiation dose before patient is treated by radiotherapy, obtain the data closest to actual irradiation condition, and problems in internal irradiation after-loading plan can be found and investigated in time, to avoid error irradiation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical verification of radiotherapy equipment, in particular to a brachytherapy dose distribution verification phantom and method. BACKGROUND

[0002] In radiotherapy technology, it is of great significance to verify the dose distribution of the radiotherapy plan. At present, in external beam radiotherapy, the method of "transplanting plan" is used to verify the accuracy of the device execution and the plan system calculation. The patient's plan (the irradiation conditions of the device) is kept unchanged, and is projected onto the phantom containing the measurement tool (film, ionization chamber, probe matrix) to obtain the dose distribution of the patient's plan in the phantom, and compared with the corresponding result calculated in the plan system. If the verification result is good, it means that the plan calculation and device execution accuracy are consistent, and as a plan irradiation to the patient, we have reason to believe that the patient receives accurate irradiation. For example, Chinese invention patent (application number 2021104465686) discloses a spiral tomography radiotherapy equipment output dose calibration phantom, which is an external beam dose calibration device. However, in the afterloading plan of internal irradiation (also known as brachytherapy), the radioactive source is placed in the human body, and the main factors affecting the dose distribution are the reconstruction accuracy of the applicator pipe, the source length, the blind end distance, etc. The parameters such as the residence point position and the residence time, which cannot be verified by the "transplanting plan" in external beam radiotherapy. How to verify the accuracy of the afterloading plan and the afterloading machine before the patient is treated is a difficult point of common concern in the industry. At present, there is no special phantom for verifying the accuracy of the internal irradiation afterloading plan and the afterloading machine in medical practice. SUMMARY

[0003] The purpose of the present application is to provide a brachytherapy dose distribution verification phantom and method to verify the dose distribution of internal irradiation radiotherapy.

[0004] In order to achieve the above purpose, the technical scheme of the present application is as follows: a brachytherapy dose distribution verification phantom, comprising a phantom applicator pipe, a phantom water tank and a mechanical arm, a radiation detector is arranged in the phantom water tank, and the mechanical arm drives the phantom applicator pipe to move, so that the phantom applicator pipe is positioned relative to the radiation detector in the phantom water tank.

[0005] Furthermore, in order to accurately position the phantom applicator pipe, the mechanical arm is a six-axis robot.

[0006] Furthermore, in order to verify the dose distribution in the water phantom, the phantom water tank is an open tank at the upper end, and the phantom applicator pipe enters the phantom water tank from the upper end of the phantom water tank.

[0007] Further, in order to adapt the mechanical arm to the positioning of the phantom applicator catheter, the phantom applicator catheter includes straight applicator catheter, curved applicator catheter and elbow applicator catheter, the driving control system of the mechanical arm records the end position and center line information of the phantom applicator catheter.

[0008] Further, a preferred configuration of the radiation detector is that the radiation detector includes a radiation detection film and an ionization chamber, and the radiation detector is installed on the side wall of the phantom water tank.

[0009] A brachytherapy dose distribution verification method includes the brachytherapy dose distribution verification phantom of any one of claims 1 to 4, and CT scan information of an in-vivo applicator catheter placed in the body, wherein the in-vivo applicator catheter is the same as the phantom applicator catheter, and the method includes the following steps:

[0010] a. According to the CT scan information of the in-vivo applicator catheter, a reference point and a plurality of catheter reference points are calibrated in the afterloading planning system, and the catheter reference points are calibrated along the center line of the in-vivo applicator catheter;

[0011] b. A reference positioning point and a plurality of catheter positioning points are specified in the brachytherapy dose distribution verification phantom, the position of the reference positioning point corresponds to the reference point, each catheter positioning point corresponds to a catheter reference point, and the coordinate position of the catheter positioning point in the brachytherapy dose distribution verification phantom is obtained;

[0012] c. The coordinate position of the catheter positioning point is input into the driving control system of the mechanical arm, and the mechanical arm drives the phantom applicator catheter to move to a verification position;

[0013] d. The phantom applicator catheter is connected to the afterloading therapy machine, the radioactive source is placed in the phantom applicator catheter, and the radiation detector records the radiation dose.

[0014] Further, a preferred phantom applicator catheter positioning method is that in step a, the catheter reference points include a catheter reference end point and one or more catheter axis reference points, the catheter reference end point is calibrated at the end position of the in-vivo applicator catheter, and the catheter axis reference points are calibrated on the center line of the in-vivo applicator catheter; in step b, the catheter positioning points include a catheter positioning end point and one or more catheter axis positioning points, the catheter positioning end point corresponds to the catheter reference end point, and each catheter axis positioning point corresponds to a catheter axis reference point; in step c, the end of the phantom applicator catheter coincides with the catheter positioning end point, and the axis of the phantom applicator catheter corresponds to the catheter axis positioning point.

[0015] Further, the in-vivo applicator catheter and the phantom applicator catheter are straight applicator catheters, in step a, the catheter reference points include a catheter reference end point and a catheter axis reference point; in step c, the center line of the phantom applicator catheter is coincided with the catheter axis reference point.

[0016] Further, the in-vivo applicator catheter and the phantom applicator catheter are curved or elbow applicator catheters, in step a, the catheter reference points include a catheter reference end point and two catheter axis reference points; in step c, the center line of the phantom applicator catheter is coincided with the catheter axis reference point far from the catheter reference end point, and the catheter axis reference point near the catheter reference end point is coincided with the plane where the center line of the phantom applicator catheter is located.

[0017] Further, a preferred dose verification method is that, in step a, the reference point is a radiation dose detection point, and in step b, the reference location point is located on the radiation detector.

[0018] The present application has the following advantages: the same phantom applicator catheter as the applicator catheter implanted in the patient is used, the information of the afterloading plan is simulated and transplanted into the phantom water tank by obtaining the location data of the applicator catheter in the patient, the radiation dose at the specified position is detected by the radiation detector, the afterloading plan setting and the equipment execution precision verification can be realized, the irradiation dose before the patient is treated can be verified, the data closest to the actual irradiation condition can be obtained, and the problems in the afterloading plan of the internal irradiation can be found and checked in time, and the wrong irradiation can be avoided.

[0019] The present application will be described in detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Fig. 1 is a structure diagram of a brachytherapy dose distribution verification phantom of the present application;

[0021] Figure 2 Fig. 2 is a structure diagram of an elbow-shaped phantom applicator catheter of the present application;

[0022] Figure 3 Fig. 3 is a structure diagram of a brachytherapy dose distribution verification phantom provided with three mechanical arms of the present application;

[0023] Figure 4 Fig. 4 is an application schematic diagram of a commonly used applicator catheter for gynecology;

[0024] Figure 5 Fig. 5 is a screenshot of the present application for calibrating the reference point and the catheter reference point of the afterloading plan system;

[0025] Figure 6 This is a schematic diagram of the reference positioning point and catheter positioning point specified in the brachytherapy dose distribution verification phantom of the present invention. The phantom water tank is omitted in the figure.

[0026] Figure 7 This is a schematic diagram of the robotic arm driving the phantom applicator conduit to the conduit positioning point of the present invention. The phantom applicator conduit is a bendable applicator conduit. The phantom water tank is omitted in the figure.

[0027] Figure 8 This is a schematic diagram of the phantom applicator conduit of the present invention to the verification position;

[0028] Figure 9 This is a schematic diagram illustrating the application of the straight applicator conduit of the present invention. Detailed Implementation

[0029] like Figure 1 , Figure 2 A brachytherapy dose distribution verification phantom includes a phantom applicator conduit 10, a phantom water tank 20, and a robotic arm 30. The phantom water tank is equipped with a radiation detector 21. The robotic arm drives the phantom applicator conduit to move, thereby positioning the phantom applicator conduit relative to the radiation detector in the phantom water tank.

[0030] The robotic arm is a six-axis robot.

[0031] The phantom water tank is an open-top tank, and the phantom applicator conduit enters the phantom water tank from the top.

[0032] like Figure 3 The phantom applicator conduit includes a straight applicator conduit 1a, a curved applicator conduit 1b, and a bent applicator conduit 10. The drive control system of the robotic arm records the end position 1T and centerline 1C information of the phantom applicator conduit.

[0033] The radiation detector includes radiation detection film and an ionization chamber, and the radiation detector is installed on the side wall of the phantom water tank.

[0034] like Figure 4 to Figure 8 A method for verifying brachytherapy dose distribution includes the aforementioned brachytherapy dose distribution verification phantom, and further includes CT scan information of an in vivo applicator catheter 40 implanted in the body, wherein the in vivo applicator catheter is the same applicator catheter as the phantom applicator catheter, and the method includes the following steps:

[0035] a. According to the CT scanning information of the in-vivo applicator catheter, a reference point (Br) and a plurality of catheter reference points (A1, A2, A3) are marked in the afterloading planning system, the catheter reference points are marked along the center line of the in-vivo applicator catheter;

[0036] b. As shown in the brachytherapy dose distribution verification phantom, a reference positioning point B and a plurality of catheter positioning points (D1, D2, D3) are specified, the position of the reference positioning point B corresponds to the reference point Br, and each of the catheter positioning points corresponds to one of the catheter reference points (in the figure, D1 corresponds to A1, D2 corresponds to A2, and D3 corresponds to A3), and the coordinate positions of the catheter positioning points in the brachytherapy dose distribution verification phantom are obtained; Figure 6

[0037] c. The coordinate positions of the catheter positioning points are input into the drive control system of the mechanical arm, and the mechanical arm drives the phantom applicator catheter to move to a verification position (as shown in the figure); Figure 7

[0038] d. The phantom applicator catheter is connected to the afterloading therapy machine, the radioactive source is put into the phantom applicator catheter, and the radiation dose is recorded by the radiation detector.

[0039] In step a, the catheter reference points include a catheter reference end point A1 and one or more catheter axis reference points (A2, A3), the catheter reference end point A1 is marked at the end position of the in-vivo applicator catheter, and the catheter axis reference points are marked on the center line of the in-vivo applicator catheter; in step b, the catheter positioning points include a catheter positioning end point D1 and one or more catheter axis positioning points (D2, D3), the catheter positioning end point corresponds to the catheter reference end point (in the figure, D1 corresponds to A1), and each of the catheter axis positioning points corresponds to one of the catheter axis reference points (in the figure, D2 corresponds to A2, and D3 corresponds to A3); in step c, the end 1T of the phantom applicator catheter coincides with the catheter positioning end point D1, and the axis of the phantom applicator catheter corresponds to the catheter axis positioning point D3.

[0040] As shown in the figure, the in-vivo applicator catheter and the phantom applicator catheter are straight applicator catheters, in step a, the catheter reference points include a catheter reference end point and a catheter axis reference point; in step b, the catheter positioning points include a catheter positioning end point D1 and a catheter axis positioning point D3, and in step c, the center line of the phantom applicator catheter coincides with the catheter axis positioning point D3. Figure 9

[0041] ​​​The in-vivo applicator catheter and the phantom applicator catheter are curved or elbow-shaped, the catheter reference points in step a include a catheter reference end point A1 and two catheter axis reference points (A2, A3), the catheter positioning points in step b include a catheter positioning end point D1 and two catheter axis positioning points (D2, D3), and the center line 1C of the phantom applicator catheter is coincided with the catheter axis positioning point D3 far from the catheter positioning end point D1, and the catheter axis positioning point D2 close to the catheter positioning end point D1 is coincided with the plane 1F where the center line of the phantom applicator catheter is located.

[0042] In step a, the reference point Br is a radiation dose detection point, and in step b, the reference positioning point B is located on the radiation detector.

[0043] Embodiment I:

[0044] As Figure 1 , Figure 2 A brachytherapy dose distribution verification phantom includes a phantom applicator catheter 10, a phantom water tank 20 and a mechanical arm 30.

[0045] The phantom applicator catheter 10 is an applicator catheter used in internal irradiation, that is, the phantom applicator catheter 10 is exactly the same as the applicator catheter used by a patient in radiotherapy. In this embodiment, the phantom applicator catheter 10 is an elbow-shaped applicator catheter, which is the most commonly used applicator catheter in the radiotherapy of gynecological tumors. The catheter has a bending section 11 and a straight section 12, the front end of the bending section 11 is a phantom applicator catheter tip 1T, and there is a center line plane 1F corresponding to the bending section 11 and the straight section 12, because the center lines of the bending section 11 and the straight section 12 intersect and are not collinear.

[0046] The phantom water tank 20 is a rectangular tank with an open upper end, and the size (length x width x height) of the inner cavity of the tank is 200 mm x 200 mm x 400 mm. The phantom water tank contains water, which is the standard medium in radiation dose verification.

[0047] The phantom water tank is provided with a radiation detector 21, which can be a radiation detection film, an ionization chamber or a two-dimensional ionization chamber array. The use of a radiation detection film has the advantage of low cost; the use of a single ionization chamber or multiple separated ionization chambers can obtain real-time dose verification results, with high efficiency and high precision; the use of a two-dimensional ionization chamber array has high efficiency and a large dose verification range, and can obtain more comprehensive detection data, but the cost is high.

[0048] The radiation detector 21 is installed on the side wall of the phantom water tank. In this embodiment, the specifications and structure of the radiation detector are not specified, and it is assumed that the thickness of the radiation detector is 20 mm.

[0049] The phantom applicator catheter 10 is installed on the mechanical arm 30, which is a six-axis robot. The six-axis robot is commonly used in the industry, and the six-axis robot has 6 degrees of freedom, and the 6 joints are combined to realize the 6 degrees of freedom of the end, and has high positioning accuracy. The driving control system of the mechanical arm can execute operation instructions and flexibly reach the required spatial position. The position of the mechanical arm and the phantom water tank is fixed so that the mechanical arm, the phantom water tank and the radiation detector are in a common coordinate system. The phantom applicator catheter is not grabbed by the mechanical arm, and the phantom applicator catheter 10 is fixedly installed on the end arm 31 (or called wrist rotation T axis) of the mechanical arm 30, which can improve the positioning accuracy and repeatability of the phantom applicator catheter. In this embodiment, the mechanical arm 30 drives the phantom applicator catheter 10 to move, so that the phantom applicator catheter 10 is positioned in the phantom water tank relative to the radiation detector. In order to realize the movement and positioning of the phantom applicator catheter, the driving control system of the mechanical arm needs to record the information of the end head 1T, the center line 1C and the plane 1F where the center line is located of the phantom applicator catheter 10.

[0050] The phantom applicator catheter 10 enters the phantom water tank from the open upper end of the phantom water tank, so that the water in the phantom water tank remains in a stable state.

[0051] The brachytherapy dose distribution verification phantom of the embodiment can accurately move the phantom applicator catheter to a specified position in the phantom water tank relative to the radiation detector, and the radiation detector can accept the radiation released from the phantom applicator catheter, so as to realize the measurement and verification of the radiation dose, and provide a detection environment closest to the reality for the brachytherapy (internal irradiation) in reality.

[0052] Embodiment two:

[0053] As Figure 3 A brachytherapy dose distribution verification phantom. The embodiment is an extension of embodiment one.

[0054] The commonly used internal irradiation applicator catheter includes a straight applicator catheter 1a, a curved applicator catheter 1b and an elbow-shaped applicator catheter 10. In this embodiment, three sets of mechanical arms 30 are provided, and the three sets of mechanical arms are respectively installed with three kinds of phantom applicator catheters: the straight applicator catheter 1a, the curved applicator catheter 1b and the elbow-shaped applicator catheter 10.

[0055] The elbow-shaped applicator catheter 10 has been introduced in embodiment one.

[0056] For the straight applicator catheter 1a, since it is a straight catheter, the driving control system of the mechanical arm only needs to record the position of the end head 1T of the phantom applicator catheter and the center line 1C information.

[0057] For the curved applicator catheter 1b, which includes a curved segment, the driving control system of the robot needs to record the information of the position of the phantom applicator catheter tip 1T and the center line 1C, and also the information of the plane 1F in which the center line is located.

[0058] The dose distribution verification of three different applicator catheters can be performed on one set of equipment, which improves the utilization rate of the equipment and reduces the application cost.

[0059] Embodiment Three:

[0060] As shown in Figure 4 to Figure 8 , a brachytherapy dose distribution verification method includes the brachytherapy dose distribution verification phantom of embodiment one, and also includes the CT scan information of the in-vivo applicator catheter 40 placed in the body, the in-vivo applicator catheter 40 is a curved applicator catheter, and the in-vivo applicator catheter 40 is the same applicator catheter as the phantom applicator catheter 10 (see embodiment one). The doctor places the in-vivo applicator catheter 40 into the patient's body according to the position of the lesion, and then fixes it, and then performs CT scanning on the lesion and the area where the in-vivo applicator catheter 40 is located to obtain the CT scan information. Then the brachytherapy dose distribution verification is performed, and the steps of the brachytherapy dose distribution verification method include:

[0061] a. As shown in Figure 4 , Figure 5 , a reference point Br is calibrated in the afterloading planning system according to the CT scan information of the in-vivo applicator catheter, the reference point Br is usually a radiation dose detection point, and the reference point Br can be the position of the lesion or other positions where the radiation dose needs to be measured. Three catheter reference points are also calibrated in the afterloading planning system, and the three catheter reference points are calibrated along the center line of the in-vivo applicator catheter. The three catheter reference points include a catheter reference end point A1 and two catheter axis reference points (A2, A3), the catheter reference end point A1 is calibrated at the tip position of the in-vivo applicator catheter, a catheter axis reference point A2 close to the catheter reference end point A1 is calibrated at the bending position of the in-vivo applicator catheter, and another catheter axis reference point A3 far from the catheter reference end point A1 is calibrated on the axis of the in-vivo applicator catheter. It should be noted that the three catheter reference points should not be calibrated on a straight line. Referring to Figure 5 , in this embodiment:

[0062] The xyz coordinate point of the reference point Br is (-10.8, -63.4, 42.9) (mm);

[0063] The xyz coordinate point of the catheter reference end point A1 is (16.0, -1.0, -11.3) (mm);

[0064] The xyz coordinates of the catheter axis reference point A2 are (12.9, -20.0, 13.4) (mm).

[0065] The xyz coordinates of the catheter axis reference point A3 are (12.7, -55.0, 16.7) (mm).

[0066] b. such as Figure 6 As shown, a coordinate system needs to be established for the brachytherapy dose distribution verification phantom to provide positioning information to the robotic arm's drive control system. This coordinate system can be established based on the phantom's water tank or the robotic arm. In this embodiment, the origin O of the brachytherapy dose distribution verification phantom is set at the bottom corner of the phantom's water tank 20 facing the robotic arm 30, which is also the outer bottom corner of the X-ray detector 21. It should be noted that the coordinate system of the brachytherapy dose distribution verification phantom differs from that of the afterloading planning system. In the afterloading planning system's coordinate system, the y-axis points towards the front end of the in vivo applicator catheter; while in the brachytherapy dose distribution verification phantom's coordinate system, the y-axis points towards the tail end of the phantom applicator catheter. The y-axis and z-axis directions of the two coordinate systems are opposite, but both coordinate systems are three-dimensional coordinate systems that conform to the right-hand rule of spatial coordinate systems. Therefore, when transferring coordinate data between the two coordinate systems, the y-coordinate values ​​and z-coordinate values ​​need to be reversed, i.e., negative values ​​are taken.

[0067] In this step, a reference point B and three catheter reference points (D1, D2, D3) are specified in the brachytherapy dose distribution verification phantom. These include a catheter endpoint D1, a catheter axis reference point D2, and a catheter axis reference point D3. Using the position of reference point B as the reference reference point Br, and based on the positional relationship between the reference reference point Br established in step a and the three catheter reference endpoints (A1, A2, A3), each of the three catheter reference points corresponds to a catheter reference point (e.g., ...). Figure 6 (D1 corresponds to A1, D2 corresponds to A2, and D3 corresponds to A3), meaning the relative position of the catheter positioning endpoint D1 to the reference positioning point B is equivalent to the relative position of the reference reference point Br to the catheter reference endpoint A1; the relative position of the catheter axis positioning point D2 to the reference positioning point B is equivalent to the relative position of the reference reference point Br to the catheter axis reference point A2; and the relative position of the catheter axis positioning point D3 to the reference positioning point B is equivalent to the relative position of the reference reference point Br to the catheter axis reference point A3. Thus, the coordinate positions of the catheter positioning points in the brachytherapy dose distribution verification phantom can be obtained, i.e., the verification position of the phantom applicator catheter is set. In this embodiment:

[0068] The xyz coordinates of the reference positioning point B are specified as (20, 300, 100) (mm), that is, the reference positioning point B is located in the upper middle part of the X-ray detector 21.

[0069] According to the position relationship between the reference reference point Br and the catheter reference end point A1 in step a, the xyz coordinate position of the catheter reference end point A1 relative to the reference reference point Br is x: 16.0-(-10.8)=26.8, y:-1-(-63.4)=62.4, z:-11.3-42.9=-54.2 (unit: mm); the catheter reference end point A1 is transplanted to the catheter positioning point D1, and the xyz coordinate position of the catheter positioning end point D1 relative to the reference positioning point B is x: 20.0+26.8=46.8, y: 300.0-62.4=237.6, z: 100.0-(-54.2)=154.2 (unit: mm); therefore, the xyz coordinate point of the catheter positioning end point D1 in the brachytherapy dose distribution verification phantom is (46.8, 237.6, 154.2) (mm).

[0070] According to the position relationship between the reference reference point Br and the catheter axis reference point A2 in step a, the xyz coordinate position of the catheter axis reference point A2 relative to the reference reference point Br is x: 12.9-(-10.8)=23.7, y:-20-(-63.4)=43.4, z: 13.4-42.9=-29.5 (unit: mm); the catheter axis reference point A2 is transplanted to the catheter axis positioning point D2, and the xyz coordinate position of the catheter axis positioning point D2 relative to the reference positioning point B is x: 20.0+23.7=43.7, y: 300.0-43.4=256.6, z: 100.0-(-29.5)=129.5 (unit: mm); therefore, the xyz coordinate point of the catheter axis positioning point D2 in the brachytherapy dose distribution verification phantom is (43.7, 256.6, 129.5) (mm).

[0071] According to the position relationship between the reference reference point Br and the catheter axis reference point A3 in step a, the xyz coordinate position of the catheter axis reference point A3 relative to the reference reference point Br is x: 12.7-(-10.8)=23.5, y:-55-(-63.4)=8.4, z: 16.7-42.9=-26.2 (unit: mm); the catheter axis reference point A3 is transplanted to the catheter axis positioning point D3, and the xyz coordinate position of the catheter axis positioning point D3 relative to the reference positioning point B is x: 20.0+23.5=43.5, y: 300.0-8.4=291.6, z: 100.0-(-26.2)=126.2 (unit: mm); therefore, the xyz coordinate point of the catheter axis positioning point D2 in the brachytherapy dose distribution verification phantom is (43.5, 291.6, 126.2) (mm).

[0072] c. As Figure 7The coordinate position of the catheter positioning point is input into the driving control system of the mechanical arm, and the mechanical arm drives the phantom applicator catheter to move to the verification position. In this step, the end 1T of the phantom applicator catheter is coincided with the catheter positioning end point D1, and the center line 1C of the phantom applicator catheter is coincided with the catheter axis positioning point D3, and since the catheter axis positioning point D3 is far away from the catheter positioning end point D1, better positioning accuracy can be obtained. Since in step a, the catheter reference point is calibrated in the afterloading planning system by a person according to the CT scan information, although the calibration is along the center line of the in-vivo applicator catheter, the CT scan image does not mark the center line of the in-vivo applicator catheter, and therefore there is a certain visual error, that is, the catheter axis positioning point D2 (the catheter axis positioning point close to the catheter positioning end point D1) cannot be guaranteed to accurately fall on the center line of the in-vivo applicator catheter. Therefore, the catheter axis positioning point D2 is coincided with the plane 1F in which the center line of the phantom applicator catheter is located in the embodiment, so that the driving control system of the mechanical arm can accurately calculate the verification position of the phantom applicator catheter and obtain the best positioning effect.

[0073] d. The phantom applicator catheter is connected to the afterloading treatment machine, the radioactive source is put into the phantom applicator catheter, and the radiation dose is recorded by the radiation detector.

[0074] The method of the embodiment can be used for dose distribution verification of the elbow-shaped applicator catheter and the curved applicator catheter.

[0075] Embodiment Four

[0076] As Figure 9 A brachytherapy dose distribution verification method.

[0077] Embodiment Three is a dose distribution verification method for the elbow-shaped applicator catheter, and the embodiment refers to the method of Embodiment One, and adopts the dose distribution verification method of the straight applicator catheter 1a.

[0078] In the embodiment, the in-vivo applicator catheter and the phantom applicator catheter are straight applicator catheters, in step a, according to the CT scan information of the in-vivo applicator catheter, a reference point, a catheter reference end point and a catheter axis reference point are calibrated in the afterloading planning system, the catheter reference end point and the catheter axis reference point are calibrated along the axis of the in-vivo applicator catheter, and the axis of the in-vivo applicator catheter is a straight line.

[0079] In step b, a reference positioning point B, a catheter positioning end point D1 and a catheter axis positioning point D3 are specified in the brachytherapy dose distribution verification phantom. With the position of the reference positioning point B as a reference point, according to the positional relationship among the reference point, the catheter reference end point and the catheter axis reference point established in step a, the relative position of the catheter positioning point D1 to the reference positioning point B is equivalent to the relative position of the reference point to the catheter reference end point, and the relative position of the catheter axis positioning point D3 to the reference positioning point B is equivalent to the relative position of the reference point to the catheter axis reference point. Thus, the coordinate position of the catheter positioning point in the brachytherapy dose distribution verification phantom can be obtained

[0080] In step c, the tip 1T of the phantom applicator catheter is overlapped with the catheter positioning end point D1, and the center line 1C of the phantom applicator catheter is overlapped with the catheter axis positioning point D3,

[0081] Since the phantom applicator catheter is a straight applicator catheter, the catheter positioning end point D1 and the catheter axis positioning point D3 can be used to accurately position the phantom applicator catheter.

[0082] Compared with embodiment three, the positioning of the phantom applicator catheter in this embodiment is simpler.

[0083] The present application can also be used for dose distribution verification of other commonly used applicator catheters or implant needles in gynecology.

[0084] The working principle of the present application is as follows:

[0085] 1. After the patient completes the implantation of the applicator or implant needle, the spatial position information of the applicator and implant needle is obtained through CT scanning. The image recognition software of the afterloading planning system identifies each applicator and implant needle channel and calibrates the spatial coordinate information, which is then sent to the brachytherapy dose distribution verification phantom.

[0086] 2. The brachytherapy dose distribution verification phantom drives the phantom applicator catheter according to the received position information, so that the phantom applicator catheter completely simulates the spatial position of the applicator channel in the CT image of the patient.

[0087] 3. After the plan design is completed in the afterloading planning system, the plan is transmitted to the afterloading machine. The phantom applicator catheter and the afterloading machine are first connected, the designed plan is executed, and the dose distribution of the relevant layers is measured through the radiation detector.

[0088] 4. The difference between the measured distribution and the planned distribution is compared, so as to determine whether the plan setting and the afterloading machine execution are correct.

[0089] Based on the application, the after-loading plan setting and the device execution precision verification can be realized, the whole verification work is completed before the dose irradiation to the patient, once the problem is found, the cause can be found in time, and the maximum error irradiation of the patient is avoided.

Claims

1. A brachytherapy dose distribution verification phantom, characterized in that, The phantom applicator catheter, the phantom water tank with a radiation detector and the mechanical arm, the mechanical arm drives the phantom applicator catheter to move, and the phantom applicator catheter is positioned relative to the radiation detector in the phantom water tank; The mechanical arm is a six-axis robot; The phantom water tank is an open-top tank, and the phantom applicator catheter enters the phantom water tank from the top of the phantom water tank; The phantom applicator catheter is an applicator catheter used in internal irradiation, and the phantom applicator catheter includes straight, curved and elbow-shaped applicator catheters, and the driving control system of the mechanical arm records the end position and center line information of the phantom applicator catheter, and moves the phantom applicator catheter to the verification position according to the position of the in-vivo applicator catheter.

2. A brachytherapy dose distribution verification phantom according to claim 1, wherein, The radiation detector includes a radiation detection film and an ionization chamber, and the radiation detector is installed on the side wall of the phantom water tank.

3. A method for verifying a brachytherapy dose distribution, comprising the brachytherapy dose distribution verification phantom according to claim 1 or 2, and CT scan information of an in-vivo applicator catheter placed in a body, characterized in that, The in-vivo applicator catheter and the phantom applicator catheter are the same applicator catheter, and the method comprises the following steps: a. According to the CT scan information of the in-vivo applicator catheter, a reference point and a plurality of catheter reference points are marked in the afterloading planning system, and the catheter reference points are marked along the center line of the in-vivo applicator catheter; b. A reference positioning point and a plurality of catheter positioning points are specified in the brachytherapy dose distribution verification phantom, the position of the reference positioning point corresponds to the reference point, each catheter positioning point corresponds to a catheter reference point, and the coordinate position of the catheter positioning point in the brachytherapy dose distribution verification phantom is obtained; c. The coordinate position of the catheter positioning point is input into the driving control system of the mechanical arm, and the mechanical arm drives the phantom applicator catheter to move to the verification position; d. The phantom applicator catheter is connected to the afterloading therapy machine, the radioactive source enters the phantom applicator catheter, and the radiation detector records the radiation dose; In step a, the catheter reference points include a catheter reference end point and one or more catheter axis reference points, the catheter reference end point is marked at the end position of the in-vivo applicator catheter, and the catheter axis reference points are marked on the center line of the in-vivo applicator catheter; in step b, the catheter positioning points include a catheter positioning end point and one or more catheter axis positioning points, the catheter positioning end point corresponds to the catheter reference end point, and each catheter axis positioning point corresponds to a catheter axis reference point; in step c, the end of the phantom applicator catheter coincides with the catheter positioning end point, and the axis of the phantom applicator catheter corresponds to the catheter axis positioning point.

4. A brachytherapy dose distribution verification method according to claim 3, wherein, The in-vivo applicator catheter and the phantom applicator catheter are straight applicator catheters, in step a, the catheter reference points include a catheter reference end point and one catheter axis reference point; in step c, the center line of the phantom applicator catheter coincides with the catheter axis positioning point.

5. The brachytherapy dose distribution verification method of claim 3, wherein, The in-vivo applicator catheter and the phantom applicator catheter are curved or elbow-shaped, the catheter reference points in step a include one catheter reference end point and two catheter axis reference points; in step c, the center line of the phantom applicator catheter is coincided with the catheter axis positioning point far from the catheter positioning end point, and the catheter axis positioning point close to the catheter positioning end point is coincided with the plane where the center line of the phantom applicator catheter is located.

6. The brachytherapy dose distribution verification method of claim 3, wherein, In step a, the reference positioning points are radiation dose detection points, and in step b, the reference positioning points are located on the radiation detector.

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