Annular source applicator after-loading treatment plan verification device

Abstract

The utility model discloses an annular source applicator after-loading treatment plan verification device, which comprises a box body and a verification module arranged in the box body, and is characterized in that the verification module is provided with two parallel film placing ports, two ionization chamber measuring holes and a center hole for placing a uterus probe; wherein one film placing port and the central hole are in the same plane and are adjacent to the central hole; the distance between the two film placing ports is 2cm, and the two ionization chamber measuring holes are both arranged on the circumference which is 2cm away from the central hole. The design can provide surface dose distribution of the center layer and the A point layer and point dose at the A point, and can provide more complete dose reference.

Description

Technical Field

[0001] The utility model belongs to the field of source applicator auxiliary devices, in particular to a ring-shaped source applicator post-installed treatment plan verification device. Background Art

[0002] High dose rate brachytherapy (HDR-BT) can effectively treat cancer by providing high-dose radiation locally and protecting organs at risk, and is widely used in afterloading therapy for cervical cancer. Since HDR-BT has a steep dose gradient, high accuracy is required for afterloading dose calculation and planned implementation. CT image-guided three-dimensional afterloading brachytherapy has become the main method for afterloading therapy. The treatment plan is to calculate the dose on the CT image, which is then transmitted and loaded into the afterloading therapy machine for execution. End-to-end testing of the entire process of dose calculation and dose transmission guided by CT images is crucial for afterloading therapy control.

[0003] At present, most quality control systems are limited to the accuracy of the radiation source delivery system, such as the accuracy of the radiation source in place, verification of the activity of the radiation source, timer accuracy and linearity check, etc. However, afterloading therapy technology has changed from two-dimensional imaging to determine the radiation source residence mode to inverse optimization technology based on patient-specific 3D images, so more complete dose verification methods and equipment are needed. Studies have shown that 3D printed phantoms have good uniformity and the error between the calculated and measured values ​​is small. Applicators made by 3D printing have been used in clinical treatment. There are 3D printing equipment to verify the afterloading dose distribution of a single tube, but there is currently no 3D printed annular applicator afterloading dose verification equipment and end-to-end test phantom.

[0004] The intracavitary irradiation dose in the commercial planning system is based on the AAPM TG43 report, which describes the dose deposition around a single radioactive source at the center of a spherical water model with unit density. Traditional external irradiation dose verification equipment cannot simulate the dose distribution of the source applicator in water. And because the radioactive source has the characteristics of multi-energy spectrum and rapid decline in a short distance, the sensitivity of the ionization chamber matrix is ​​required to be high. The ionization chamber can only obtain the accuracy and activity test of the radioactive source, and the annular source applicator is irregular, and the measurement of the rear-mounted surface dose cannot be obtained. Other detectors, such as micro MOSFET detectors, have dose response dependence, especially angle dependence, and the measurement results still need to be corrected. Gel dosimeters can achieve spatial dose distribution, but their related special effects must meet the requirements of dose measurement, such as stability, spatial integrity, temperature dependence, dose rate and energy dependence, and the above performance changes must be paid attention to at any time during measurement. Therefore, the gel dosimeter has poor operability. Other in-body dose verification equipment can only measure point doses and cannot provide complete dose distribution. Summary of the invention

[0005] In view of the shortcomings and deficiencies of the prior art, the utility model provides a ring-shaped applicator after-loading treatment plan verification device. In a water environment, a wash-free developing film is used to measure the surface dose distribution of the central axis and the dose reference point A layer, and an ionization chamber is used to measure the dose reference point dose, providing a more complete dose description.

[0006] The utility model discloses a ring-shaped source applicator after-installation treatment plan verification device, comprising a box body and a verification module placed inside the box body, wherein two parallel film placement ports are arranged on the verification module. 、 There are two ionization chamber measurement holes and a central hole for placing a uterine probe; one of the film placement holes is in the same plane as the central hole and is adjacent to the central hole; the distance between the two film placement holes is 2 cm, and the two ionization chamber measurement holes are both on a circle 2 cm away from the central hole.

[0007] Preferably, the central hole and the two ionization chamber measurement holes are blind holes.

[0008] Preferably, the side wall of the box body is provided with a uterine probe fixing hole and a ring probe fixing hole.

[0009] Preferably, the central hole and the two ionization chamber measurement holes are located on the same side wall of the module.

[0010] Preferably, the module and the box are both rectangular structures.

[0011] Preferably, the two film placement holes overlap in spatial projection.

[0012] Preferably, the uterine probe fixing hole and the annular probe fixing hole are arranged near the bottom of the box.

[0013] Preferably, the box and the module are both 3D printed products.

[0014] The advantages of the utility model are:

[0015] The present invention provides a device for verifying the dose of after-treatment of an annular applicator in water. Through the positional relationship between two layers of wash-free films and the central hole, and the positional relationship between the central hole and two ionization measurement holes, the surface dose distribution of the central layer and the dose reference point A layer, as well as the point dose at the dose reference point A, is simulated by 3D printing. The phantom can provide the surface dose distribution of the annular applicator in water and the dose reference point dose, providing effective after-treatment dose verification results for treatment effect operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0017] Figure 2 It is a schematic diagram of the installation of the utility model.

[0018] Figure 3 It is a schematic diagram of the box of the utility model.

[0019] Figure 4 It is a schematic diagram of the verification module of the utility model. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0021] Terminology explanation: Dose reference point A is the dose reference point for post-loading intracavitary treatment, which is located 2 cm upward from the center of the external cervical os and 2 cm away from the paracervical tissue, namely the paracervical triangle.

[0022] Wash-free radiation film is a special film that changes the color of plastic based on the radiation cross-linking effect to reflect the dose change. It is widely used in the field of radiotherapy dose verification. Not only can it provide two-dimensional dose distribution, but the dose-calibrated quantitative film can also be used for dose measurement. Due to its good spatial ductility, easy operation, and no environmental restrictions, wash-free film is widely used in clinical commonly used machine quality control and dose verification, including linear accelerators and close-range therapy machines.

[0023] The utility model is a 3D printed annular applicator after-loading treatment plan verification device, which mainly fixes the annular applicator and provides a place for placing films and ionization chambers for measuring dose distribution and point dose. Figure 1-4 As shown, the device includes a box 1 and a verification module 2; the verification module 2 is provided with two parallel film placement openings, two ionization chamber measurement holes and a central hole 5 for placing a uterine probe; one of the film placement openings 8 is in the same plane as the central hole 5 and is adjacent to the central hole; the distance between the two film placement openings is 2 cm, and the two ionization chamber measurement holes are both on a circumference 2 cm away from the central hole.

[0024] The annular applicator consists of an annular probe and a uterine probe. The uterine probe and the annular probe are a combination, and their positional relationship is fixed by a special buckle, which is a unique structure of the annular applicator.

[0025] like Figure 3 As shown, the box body 1 is provided with a fixing hole 3 for installing and fixing the ring probe and a fixing hole 4 for the uterine probe, which are used to fix the ring probe and the uterine probe respectively, so as to install the ring source applicator. When in use, the ring probe is placed into the box body 1 through the fixing hole 3, and the uterine probe is placed into the box body 1 through the fixing hole 4. Tighten them to fix them on the box body 1. At this point, the ring source applicator is installed.

[0026] Then, the verification module 2 is placed on the uterine probe 4 through the center hole 5. The module is customized according to the angle and distance of the uterine probe, and its aperture and length are consistent with the diameter of the uterine probe, so the verification module can be fixed on the probe, and the entire uterine probe is completely embedded in the verification module 2. The verification module 2 can just be in full contact with the bottom of the box 1 to ensure that the position of the phantom is fixed. Among them, the reference numerals 8 and 9 are the places where the wash-free film is placed. No. 8 is used to measure the dose distribution of the central axis, and No. 9 is the dose distribution at 2 cm from the central axis, that is, the dose reference point A level. The rectal ionization chamber 6 and the bladder ionization chamber 7 are placed for point dose measurement. At this point, the verification phantom is assembled.

[0027] When in use, the uterine probe and the ring probe are connected to the afterloading treatment machine with a connecting tube, the wash-free film is placed in the film placement 8 and 9 respectively, the rectal ionization chamber is placed in the measuring hole 6, and the bladder ionization chamber is placed in the measuring hole 7. After the ionization chamber is connected to the electrometer, the verification plan and the afterloading dose verification can be executed. After the installation is completed, water is injected into the box 1, and the entire verification module, ionization chamber and film are completely placed in the water to simulate the dose calculation environment in the planning system. After executing the verification plan, the result analysis is completed by comparing the surface dose distribution measured by the film with the surface dose distribution calculated by the planning system, and the point dose measured by the rectal ionization chamber and the bladder ionization chamber with the point dose calculated by the planning system.

[0028] The utility model provides a device for verifying the dose of after-treatment of an annular applicator in water, which is consistent with the calculation environment in the planning system and has more accurate results. Traditional dose verification equipment can only provide the accuracy and activity test of the radiation source in place, but cannot provide a complete dose distribution. The utility model can provide the surface dose distribution of the center layer and the A point layer, as well as the point dose at point A, and can provide a more complete dose reference.

[0029] The specific embodiments of the present invention are described in detail above, but they are only one of the embodiments, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modification and substitution of the present invention are also within the scope of the present invention. Therefore, the equivalent transformation and modification made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A treatment plan verification device for a ring-shaped applicator, characterized in that: The invention comprises a box body (1) and a verification module (2) disposed inside the box body, wherein the verification module (2) is provided with two parallel film placement openings, two ionization chamber measurement holes and a central hole (5) for placing a uterine probe; one of the film placement openings (8) is in the same plane as the central hole (5) and is adjacent to the central hole; the distance between the two film placement openings is 2 cm, and the two ionization chamber measurement holes are both on a circumference 2 cm away from the central hole.

2. The annular applicator after-loading treatment plan verification device according to claim 1 is characterized in that: The central hole (5) and the two ionization chamber measurement holes are all blind holes.

3. The annular applicator after-loading treatment plan verification device according to claim 1 is characterized in that: The side wall of the box body is provided with a uterine probe fixing hole (3) and a ring probe fixing hole (4).

4. The annular applicator after-loading treatment plan verification device according to claim 1 is characterized in that: The central hole (5) and the two ionization chamber measurement holes are all located on the same side wall of the verification module.

5. The annular applicator after-loading treatment plan verification device according to claim 1 is characterized in that: The verification module (2) and the box body (1) are both rectangular structures.

6. The annular applicator after-loading treatment plan verification device according to claim 1, characterized in that: The two film placement openings overlap in vertical projection in space.

7. The annular applicator after-loading treatment plan verification device according to claim 3 is characterized in that: The uterine probe fixing hole (3) and the annular probe fixing hole (4) are arranged near the bottom of the box.

8. The annular applicator after-loading treatment plan verification device according to claim 1 is characterized in that: The box body (1) and the verification module (2) are both 3D printed products.

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