A source applicator for verifying the actual dose in afterloading radiotherapy of cervical cancer

Abstract

The utility model relates to the technical field of applicator in cervical cancer radiotherapy, disclose a kind of verification cervical cancer after-loading radiotherapy real dose applicator, including applicator body and thermoluminescence detector.Applicator body includes guide tube and radioactive source support block, the one end of guide tube is used to connect with after-loading therapeutic instrument, radioactive source support block is fixedly connected with the other end of guide tube, and radioactive source support block is internally provided with the radioactive source cavity matched with the other end of guide tube, and installation groove is provided on the outer surface of radioactive source support block, and thermoluminescence detector is detachably installed in installation groove.It can improve the low problem of dose verification accuracy of conventional applicator in prior art.

Description

Technical Field

[0001] This utility model relates to the field of applicator technology in radiotherapy for cervical cancer, and in particular to an applicator for verifying the actual dose in brachytherapy for cervical cancer. Background Technology

[0002] Brachytherapy is a localized radiation therapy used for cervical cancer. Before treatment, imaging techniques (such as CT and MRI) are used to determine the location and size of the tumor. The doctor places the applicator through the patient's uterine cavity near the tumor. The physicist reconstructs the path of the applicator in the patient's body and calculates the dose distribution in the patient's body using a radiation therapy planning system. After the doctor confirms that the clinical treatment needs are met, a computer-controlled stepper motor delivers the radiation source to the pre-placed applicator. After treatment, the radiation source is returned to the brachytherapy machine, and the applicator in the patient's body is removed by medical staff.

[0003] Quality control is a crucial aspect of afterloading radiotherapy, primarily aimed at ensuring the precision of patient treatment. Quality control is divided into equipment quality control and dose verification. Equipment quality control is now relatively well-established, guaranteeing accuracy. Dose verification ensures that the actual dose received by the patient during treatment matches the dose calculated by the planning system. However, because afterloading radiotherapy is an internal irradiation therapy, with radiation emanating from inside the patient's body, dose verification presents significant challenges. The relationship between afterloading dose distribution and source distance is mainly reflected in the inverse square law, meaning that in the radiation field of a point source, the dose rate at a point is inversely proportional to the square of the distance between that point and the source. Specifically, in afterloading radiotherapy, the dose in surrounding tissues decreases rapidly with increasing distance from the radiation source. This is because the radiation emitted by the source gradually attenuates as it penetrates tissue; the farther away from the source, the lower the dose received. Therefore, when performing afterloading radiotherapy, physicians need to accurately calculate the location and dose of the radiation source based on factors such as the type, size, location, and stage of the tumor to ensure the effectiveness and safety of the treatment. At the same time, it is also necessary to monitor and evaluate the actual irradiation dose through dose verification in order to further ensure the accuracy and reliability of the treatment plan.

[0004] However, when using a conventional applicator tip inserted into the patient's vagina and uterus, the target area position may change due to intestinal movement, bladder volume changes, and other factors during actual treatment. The change in the target area position during brachytherapy has a significant impact on dose distribution. Existing matrix ionization chamber dose verification methods use models to replace real patients, ignoring these possible positional changes, resulting in measurement results that do not match reality and have a certain degree of uncertainty. This makes it impossible to guarantee the accuracy and reliability of the treatment plan. Utility Model Content

[0005] To overcome the above shortcomings, this invention provides an applicator for verifying the true dose in brachytherapy for cervical cancer, aiming to improve the low dose verification accuracy of traditional applicators in the prior art.

[0006] To achieve the above objectives, this utility model adopts the following technical solution: an applicator for verifying the actual dose in brachytherapy for cervical cancer, comprising an applicator body and a thermoluminescent detector.

[0007] The applicator body includes a guide tube and a radiation source support block. One end of the guide tube is used to connect to the afterloading therapy device. The radiation source support block is fixedly connected to the other end of the guide tube. The radiation source support block has a radiation source cavity inside that matches the other end of the guide tube. The outer surface of the radiation source support block has a mounting groove. The thermoluminescent detector is detachably mounted in the mounting groove.

[0008] Optionally, a snap-fit ​​protrusion is provided on the side wall of the mounting groove.

[0009] Optionally, the mounting groove is provided with an openable cover plate, one end of which is hinged to one side of the opening of the mounting groove, and the other end of which is connected to the other side of the opening of the mounting groove.

[0010] Optionally, the opening of the mounting slot is a square with a side length of 5mm.

[0011] Optionally, two applicator bodies are provided, and the middle parts of the guide tubes of the two applicator bodies are rotatably connected by a rotating connection. The ends of the two guide tubes away from the radiation source support block are connected by a handle. The two applicator bodies are configured to rotate the two guide tubes relative to the rotating connection by turning the handle, so that the radiation source support block connected to the two guide tubes moves closer to or further away from the rotating connection.

[0012] Optionally, the side of the radiation source support block in each of the two source bodies that is far apart from each other is provided with an arc surface.

[0013] Optionally, it also includes an intrauterine applicator, which includes an intrauterine guide tube and an intermediate support block. The intrauterine guide tube is fixedly inserted through the rotating connection portion. The guide tubes of the two applicator bodies are symmetrically arranged relative to the intrauterine guide tube. The intermediate support block is inserted through the intrauterine guide tube and located between the radiation source support blocks of the two applicator bodies.

[0014] Optionally, the other end of the guide tube is provided with a bent section arranged at an angle to the tube body of the guide tube, and the radiation source support block is connected to the end of the bent section.

[0015] Optionally, the bend in the pipe is telescopically located at the other end of the guide pipe.

[0016] Optionally, the radiation source support block is connected to the other end of the guide tube, and the intermediate support block is connected to the intrauterine guide tube by bolts.

[0017] Compared with related technologies, the present invention has at least the following beneficial effects:

[0018] Before brachytherapy, the doctor places a small, disc-shaped thermoluminescent detector into a mounting slot on the radiation source support block. The doctor then holds one end of the guide tube and the brachytherapy device and inserts the radiation source support block into the patient's body until it reaches the treatment site. After a CT scan confirms the correct location, the image is transmitted to the radiotherapy planning system. The system performs simulations to calculate the dose distribution of the tumor and normal tissues within the patient. Once the doctor confirms that the treatment meets clinical requirements, the treatment is initiated. During treatment, the doctor guides the radiation source through the guide tube into the radiation source cavity within the support block. According to the pre-designed radiotherapy plan, the computer controls the radiation source to remain at different locations for appropriate times. This process generates radiation to treat the patient. The thermoluminescent detector, installed in the mounting slot, stores the accumulated radiation energy received throughout the treatment process at the location closest to the treatment site. After the scheduled treatment is completed, the applicator is removed from the patient's body, and the thermoluminescent detector in the mounting slot is taken out. The count is read on a dedicated thermoluminescent reader to obtain the actual radiation dose received at the location where the thermoluminescent detector was placed during this treatment. This dose is then compared with the dose simulated and calculated by the planning system. The difference between the two helps doctors assess the accuracy of the plan and the effectiveness of the protocol, providing a reference for adjusting the next treatment plan and improving the low accuracy of dose verification of traditional applicators in existing technologies. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of an applicator for verifying the actual dose in afterloading radiotherapy for cervical cancer, as proposed in this utility model.

[0020] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0021] Figure 3 This is a schematic diagram of the front end structure of an applicator for verifying the actual dose in brachytherapy for cervical cancer, as proposed in this utility model.

[0022] Figure 4This is a schematic diagram showing the open state of the upper cover plate of the radioactive source support block proposed in this utility model.

[0023] Legend:

[0024] 1-Applicator body; 2-Thermoluminescent detector; 3-Rotating connection; 4-Handle; 5-Intrauterine applicator; 11-Guide tube; 12-Radiation source support block; 12a-Arc surface; 51-Intrauterine guide tube; 52-Intermediate support block; 111-Bend section; 121-Mounting groove; 122-Cover plate; 1211-Snap-fit ​​protrusion. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Figure 1 This is a three-dimensional structural schematic diagram of an applicator for verifying the actual dose in afterloading radiotherapy for cervical cancer, as proposed in this utility model. Figure 2 for Figure 1 A magnified view of a portion of point A in the middle; Figure 3 This is a schematic diagram of the front end structure of an applicator for verifying the actual dose in brachytherapy for cervical cancer, as proposed in this utility model. Figure 4 This is a schematic diagram showing the open state of the upper cover plate of the radiation source support block proposed in this utility model. Figures 1 to 4 As shown, this utility model provides an applicator for verifying the actual dose in brachytherapy for cervical cancer, including an applicator body 1 and a thermoluminescent detector 2.

[0027] The applicator body 1 includes a guide tube 11 and a radiation source support block 12. One end of the guide tube 11 is used to connect to the afterloading therapy device, and the radiation source support block 12 is fixedly connected to the other end of the guide tube 11. The radiation source support block 12 has a radiation source cavity inside that matches the other end of the guide tube 11. The outer surface of the radiation source support block 12 has a mounting groove 121, and the thermoluminescent detector 2 is detachably installed in the mounting groove 121.

[0028] In this embodiment of the invention, before brachytherapy, the doctor can place the thermoluminescent detector 2, which is in the shape of a small disc, into the mounting slot 121 on the radiation source support block 12. Then, the doctor holds the guide tube 11 and one end of the brachytherapy device and inserts the end of the radiation source support block 12 into the patient's body until the radiation source support block 12 reaches the area in the patient's body that needs treatment. For example, in this scheme, the radiation source support block 12 will eventually stop at the external os of the patient's cervix. After the position is confirmed by CT scan, the image is transmitted to the radiotherapy planning system. The radiotherapy planning system performs simulation calculations to obtain the dose distribution of the tumor and normal tissue in the patient's body. After the doctor confirms that the clinical treatment needs are met, the treatment is implemented. During treatment, the doctor inserts the radiation source into the radiation source cavity within the radiation source support block 12 via the guide tube 11 using a brachytherapy device. According to the pre-designed radiotherapy plan, the computer controls the radiation source to remain at different positions for appropriate durations. This process generates radiation to treat the patient. The thermoluminescent detector 2, installed in the mounting slot 121, stores the accumulated radiation energy received during the entire treatment process at the position closest to the treatment site. After the predetermined treatment time is completed, the applicator is removed from the patient's body, and the thermoluminescent detector 2 is taken out of the mounting slot. The count is read on a dedicated thermoluminescent reader, providing the actual radiation dose received at the location where the thermoluminescent detector 2 was placed during this treatment. This dose is then compared with the dose simulated and calculated by the planning system. The difference helps the doctor assess the accuracy and effectiveness of the plan, providing a reference for adjusting the next treatment plan and improving the low dose verification accuracy of traditional applicators in existing technologies.

[0029] Optionally, a snap-fit ​​protrusion 1211 is provided on the side wall of the mounting groove 121. Exemplarily, the thermoluminescent detector 2 is a lithium fluoride inorganic compound solid material sheet with a mirror structure, shaped like a disc, with dimensions of φ4.5*0.80mm. Due to its inherent properties, it can attract opposite charges to form "traps." When irradiated by X-rays, electrons and positive ions generated in the solid are captured by these traps. After treatment, by heating the solid material, the released electrons and positive ions recombine with opposite charges in other parts of the solid and emit light. The thermoluminescent detector 2 can store and accumulate the energy of the received rays. After heating, the dosimeter element emits photons, which pass through a photomultiplier tube to generate a photocurrent, which is then amplified by a DC amplifier and finally recorded by a recorder. Therefore, the actual radiation dose received by the patient can be calculated by measuring the intensity of the thermoluminescence. Comparing the measured actual radiation dose with the dose simulated in the treatment planning system can help doctors assess the accuracy of the treatment plan and the effectiveness of the protocol. In this embodiment of the present invention, a snap-fit ​​protrusion 1211 is provided on the inner side wall of the positive direction mounting groove 121 with an opening size of 5*5mm, forming a snap-fit ​​structure in the groove. This allows the circular thermoluminescent detector 2 to be limited and fixed by the snap-fit ​​protrusion 1211 after being embedded in the mounting groove 121, preventing the thermoluminescent detector 2 from falling into the patient's body during treatment and improving treatment safety.

[0030] Optionally, the mounting groove 121 is provided with an openable cover plate 122. One end of the cover plate 122 is hinged to one side of the opening of the mounting groove 121, and the other end of the cover plate 122 is connected to the other side of the opening of the mounting groove 121. Exemplarily, in this embodiment of the present invention, by providing a cover plate 122 structure hinged to the radiation source support block 12 at the opening of the mounting groove 121, the cover plate 122 is opened to expose the mounting groove 121 when the thermoluminescent detector 2 is installed and removed. When surgical treatment is required, the cover plate 122 is fastened to cover the mounting groove 121 and the thermoluminescent detector 2. After the cover plate 122 is rotated and fastened, its outer surface smoothly transitions to the outer surface of the radiation source support block 12, ensuring sealing while increasing the overall integrity of the radiation source support block 12, avoiding collisions and scrapes with the patient's internal tissues, preventing additional damage to the patient, and further improving treatment safety.

[0031] Optionally, two applicator bodies 1 are provided. The guide tubes 11 of the two applicator bodies 1 are rotatably connected at their middle parts via a rotating connecting part 3. The ends of the two guide tubes 11 away from the radiation source support block 12 are connected via a handle part 4. The two applicator bodies 1 are configured to rotate the two guide tubes 11 relative to the rotating connecting part 3 by turning the handle part 4, so that the radiation source support block 12 connected to the two guide tubes 11 moves closer to or away from them. Exemplarily, in this embodiment of the present invention, two applicator bodies 1 are provided. After they are inserted into the patient's body together, the front radiation source support blocks 12 respectively contact the two sides of the external os of the cervix of the patient, so as to use a radiation source to perform radiotherapy on the external os of the cervix. The rotating connecting part 3 is used to hinge the middle of the guide tubes 11 of the two applicator bodies 1, and a handle part 4 is provided at the end of the two guide tubes 11 away from the radiation source support block 12 for the operator to turn and adjust. The distance between the two guide tubes 11 on this side is controlled by the handle part 4, thereby controlling the radiation source support block 12 on the two guide tubes 11 to move closer or further away, realizing indirect position adjustment to adapt to the treatment position changes of different patients' cervix, and improving the adaptability of the applicator.

[0032] Optionally, the two applicator bodies 1 have a circular arc surface 12a on the side of the radiation source support block 12 that is far apart from each other. Exemplarily, in this embodiment of the invention, as the handle 4 is adjusted, the radiation source support block 12 moves within the patient's body to the designated treatment position through changes in spacing. As the position contacting the external os of the cervix and the surrounding vagina, the smooth circular arc surface 12a on the side of the two radiation source support blocks 12 that is far apart from each other serves as the contact surface. This reduces potential bumps and scratches during contact with the patient's body, while increasing the contact surface to ensure the stability of the applicator within the patient's body, further improving treatment safety.

[0033] Optionally, it also includes an intrauterine applicator 5, which includes an intrauterine guide tube 51 and an intermediate support block 52. The intrauterine guide tube 51 is fixedly inserted into the rotating connection part 3. The guide tubes 11 of the two applicator bodies 1 are symmetrically arranged relative to the intrauterine guide tube 51. The intermediate support block 52 is inserted through the intrauterine guide tube 51 and located between the radiation source support blocks 12 of the two applicator bodies 1. Exemplarily, in this embodiment of the present invention, the applicator as a whole is also provided with an intrauterine applicator 5 located in the middle of the two applicator bodies 1. It is used to extend into the external os of the cervix after entering the patient's body according to the radiotherapy plan. The intrauterine guide tube 51 provides an insertion position for the radiation source to remain inside the patient's uterus for radiotherapy. By setting the intermediate support block 52 on the intrauterine guide tube 51, it cooperates with the intermediate support blocks 52 on both sides to achieve contact isolation, avoid mutual collision and interference between the intrauterine guide tube 51 and the guide tubes 11 on both sides, and ensure the stability of the entire applicator.

[0034] Optionally, the other end of the guide tube 11 is provided with a curved section 111 arranged at an angle to the body of the guide tube 11, and the radiation source support block 12 is connected to the end of the curved section 111. Exemplarily, in this embodiment of the invention, the radiation source follows the guide tube 11 along the patient's vagina towards the uterus. The external os of the cervix of a woman has a T-shaped structure. To better adapt to the patient's internal structure, a curved section 111 is provided at the insertion end of the guide tube 11. After entering the patient's vagina, the two radiation source support blocks 12 are stretched outwards in opposite directions via the curved section 111 to form a figure-eight shape, thereby better conforming to the patient's internal structure. This allows the radiation source support blocks 12 to smoothly conform to both sides of the external os of the cervix, improving the overall treatment effect.

[0035] Optionally, the curved section 111 is telescopically disposed at the other end of the guide tube 11. Exemplarily, in this embodiment of the present invention, the curved section 111 can be telescopically extended or retracted relative to the other end of the guide tube 11 to accommodate the vaginal length of different patients, ensuring that the radiation source support block 12 can accurately and stably reach the radiotherapy position, further improving adaptability.

[0036] Optionally, the other end of the radiation source support block 12 and the guide tube 11, as well as the intermediate support block 52 and the intrauterine guide tube 51, are all connected by bolts. Exemplarily, in this embodiment of the invention, both the radiation source support block 12 and the intermediate support block 52 have bolt holes in their middle portions. After the radiation source support block 12 and the guide tube 11 are combined, and when the intermediate support block 52 is inserted into the intrauterine guide tube 51 and adjusted to the required position, they can be securely connected by inserting bolts. This design is simple, easy to assemble and disassemble, and improves usability.

[0037] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An applicator for verifying the actual dose during brachytherapy for cervical cancer, comprising: The source generator body (1) and the thermoluminescent detector (2), The applicator body (1) includes a guide tube (11) and a radiation source support block (12). One end of the guide tube (11) is used to connect to the afterloading therapy device. The radiation source support block (12) is fixedly connected to the other end of the guide tube (11). The radiation source support block (12) has a radiation source cavity inside that matches the other end of the guide tube (11). The outer surface of the radiation source support block (12) is provided with a mounting groove (121). The thermoluminescent detector (2) is detachably installed in the mounting groove (121).

2. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 1, characterized in that: The mounting groove (121) has a snap-fit ​​protrusion (1211) protruding from its side wall.

3. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 1, characterized in that: The mounting groove (121) is provided with an openable cover plate (122), one end of the cover plate (122) is hinged to one side of the opening of the mounting groove (121), and the other end of the cover plate (122) is connected to the other side of the opening of the mounting groove (121).

4. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 1, characterized in that: The opening of the mounting groove (121) is a square with a side length of 5mm.

5. An applicator for verifying the actual dose in brachytherapy for cervical cancer according to any one of claims 1 to 4, characterized in that: Two applicator bodies (1) are provided. The middle parts of the guide tubes (11) of the two applicator bodies (1) are rotatably connected by a rotating connection (3). The ends of the two guide tubes (11) away from the radiation source support block (12) are connected by a handle (4). The two applicator bodies (1) are configured to rotate the two guide tubes (11) relative to the rotating connection (3) by turning the handle (4), so that the radiation source support block (12) connected to the two guide tubes (11) moves closer to or away from the radiation source support block (12).

6. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 5, characterized in that: An arc surface (12a) is provided on the side of the radiation source support block (12) in the two source bodies (1) that are far apart from each other.

7. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 5, characterized in that: It also includes an intrauterine applicator (5), which includes an intrauterine guide tube (51) and an intermediate support block (52). The intrauterine guide tube (51) is fixedly inserted through the rotating connection part (3). The guide tubes (11) of the two applicator bodies (1) are symmetrically arranged relative to the intrauterine guide tube (51). The intermediate support block (52) is inserted through the intrauterine guide tube (51) and located between the radiation source support blocks (12) of the two applicator bodies (1).

8. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 7, characterized in that: The other end of the guide tube (11) is provided with a curved section (111) arranged at an angle to the tube body of the guide tube (11), and the radiation source support block (12) is connected to the end of the curved section (111).

9. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 8, characterized in that: The bent section (111) is telescopically located at the other end of the guide tube (11).

10. The applicator for verifying the actual dose in brachytherapy for cervical cancer according to claim 7, characterized in that: The radiation source support block (12) and the other end of the guide tube (11), as well as the intermediate support block (52) and the intrauterine guide tube (51), are all connected by bolts.

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