Novel carbon ion dosimetry and test phantom for radiotherapy

Abstract

The application relates to the technical field of medical equipment, in particular to a novel dose calibration and test phantom for carbon ion radiotherapy, which comprises a phantom main body, one end of the phantom main body is provided with a leveling nut, the phantom main body is a cuboid structure and one side surface thereof is a beam incidence surface, a mark for marking the axis of the beam incidence surface is arranged at the central position of the one side surface of the phantom main body, the mark is in a cross line structure, a clamping groove group extending to the one side surface is arranged in the phantom main body, a plug-in plate which can be detached and removed is arranged in the clamping groove group, the clamping groove group comprises a first clamping groove, a second clamping groove, a third clamping groove and a fourth clamping groove which are sequentially arranged in the direction from the beam incidence surface to the leveling nut, and the plug-in plate comprises common plug-in plates, Markus ionization chamber adaptive plug-in plates and Fammer ionization chamber adaptive plug-in plates which are the same in shape size. The novel dose calibration and test phantom can improve the convenience of dose calibration and standard plan test in a carbon ion treatment system.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a novel dosage calibration and testing phantom for carbon ion radiotherapy. Background Technology

[0002] Heavy ion beams are hailed as the most ideal radiation therapy due to their unique physical and biological advantages, and heavy ion therapy technology has developed rapidly. In domestically produced carbon ion therapy systems, there are currently two beam delivery technologies. In the passive uniform scanning mode, the modulation equipment required on the beamline includes multi-leaf gratings, ridge filters, and range shifters, etc. Furthermore, patients' tumor lesions have different treatment depths. Therefore, there are tens of thousands of possible combinations of beam delivery parameters. It is clearly impractical to calibrate all combinations before the machine is put into clinical treatment. Therefore, it is necessary to complete the specific dose calibration according to the patient's treatment plan before treatment. This work requires setting up a three-dimensional water tank. The water tank used for carbon ion system testing is huge and time-consuming to set up, requiring two physicists to work together for about 30 minutes each time. After the test, disassembly and cleanup also take about 20 minutes.

[0003] In addition, before each heavy ion therapy session, the physicist needs to perform quality control on the equipment. One of the quality control items is the heavy ion standard plan test, which aims to determine the accuracy of the machine's beam dose delivery by testing the planned point dose of a standard phantom. Previously, the procedure involved stacking solid water 1 cm apart, creating a treatment plan based on different energy requirements at the corresponding Bragg peak depth, and then placing an ionization chamber at the appropriate depth for measurement. As before, this measurement involved placing scattered solid water and installing the ionization chamber, a relatively cumbersome process. Furthermore, a set of solid water is generally not prepared in each treatment room, requiring a check in each room during the morning inspection.

[0004] Currently, in the uniform scanning mode of domestically produced carbon ion therapy systems, the modulation equipment required on the beamline includes multi-leaf gratings, ridge filters, and range shifters. Furthermore, patients' tumor lesions have varying treatment depths. Therefore, there are tens of thousands of possible combinations of beam delivery parameters. It is clearly impractical to calibrate all combinations before the machine is deployed for clinical treatment. Therefore, it is necessary to perform specific dose calibration according to the patient's treatment plan before treatment. On the other hand, quality control before carbon ion therapy, specifically testing the accuracy of the output dose at each treatment terminal, involves creating a standard plan within a phantom, which selects different depths in the ionization chamber for different energies or energy ranges to test the absolute dose.

[0005] However, due to the technical difficulty and high cost of heavy ion therapy, it has not yet been widely adopted globally, with only a few countries using it clinically. Therefore, there are no specialized tools for certain quality control items or tests related to heavy ion therapy; each institution using the therapy designs methods based on existing equipment to complete these tests. Utility Model Content

[0006] To improve the convenience of dose calibration and standard plan testing in carbon ion therapy systems, this application provides a novel dose calibration and testing phantom for carbon ion radiotherapy.

[0007] The novel carbon ion radiotherapy dose calibration and testing phantom provided in this application adopts the following technical solution: it includes a phantom body, with a leveling nut at one end of the phantom body. The phantom body has a cuboid structure and one side is a beam inlet surface. A mark for marking the axis of the beam inlet surface is provided at the center of one side of the phantom body. The mark is in the shape of a cross. The phantom body has a set of slots extending to one side. The slots have inserts that can be inserted and removed. The slots include a first slot, a second slot, a third slot, and a fourth slot arranged sequentially along the beam inlet surface to the leveling nut. The inserts include ordinary inserts with the same external dimensions, Markus ionization chamber adapter inserts, and Fammer ionization chamber adapter inserts. The first slot, the second slot, the third slot, and the fourth slot have the same structure.

[0008] Optionally, the distance between the first card slot and the beam inlet surface is 17mm, the distance between the second card slot and the beam inlet surface is 85mm, the distance between the third card slot and the beam inlet surface is 150mm, and the distance between the fourth card slot and the beam inlet surface is 210mm.

[0009] Optionally, the length of the insert plate is greater than the depth of the slot, and one end of the insert plate located outside the main body of the mold is provided with a connecting ear that is integral with the insert plate structure.

[0010] Optionally, the Markus ionization chamber adapter plate is provided with a groove for use with the Markus ionization chamber.

[0011] Optionally, the Fammer ionization chamber adapter plate is provided with a slot for use with the Fammer ionization chamber.

[0012] In summary, this application includes the following beneficial technical effects: 1. The phantom body and insert plates that can be inserted into or removed from the phantom body are set up to integrate the two functions of dose calibration and standard plan test into the same phantom. This eliminates the need for the equipment to switch between the three-dimensional water tank and solid water in existing technologies, and also eliminates the need to readjust the measurement system, simplifying the quality control operation process. At the same time, the distributed design of the slot group along the beam direction can cover the testing needs of different treatment depths. 2. The insert plates include ordinary insert plates, Markus ionization chamber adapter insert plates, and Fammer ionization chamber adapter insert plates. They can be adapted to commonly used clinical ionization chambers such as Markus and Fammer and are easy for a single person to complete the phantom transportation, insert plate switching and positioning. The combination design of the cross-shaped positioning of the beam injection surface and the leveling nut shortens the positioning and horizontal adjustment time. 3. The main body of the phantom is made of PMMA material, which is inexpensive and fully matches the parameters of the treatment planning system, avoiding dosage calculation deviations caused by the unevenness of existing solid water materials. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the novel carbon ion radiotherapy dose calibration and testing phantom of this application; Figure 2 This is a top view of the novel carbon ion radiotherapy dose calibration and testing phantom of this application; Figure 3 This is a front view of the novel carbon ion radiotherapy dose calibration and testing phantom insert plate of this application.

[0014] Reference numerals: 1. Main body of the mold; 2. Leveling nut; 3. Beam inlet surface; 4. Mark; 5. First slot; 6. Second slot; 7. Third slot; 8. Fourth slot; 9. Ordinary insert plate; 10. Markus ionization chamber adapter insert plate; 11. Fammer ionization chamber adapter insert plate. Detailed Implementation

[0015] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0016] This application discloses a novel dose calibration and testing phantom for carbon ion radiotherapy. For example... Figure 1 and 2As shown, the device includes a main body 1, with a leveling nut 2 at one end. The leveling nut 2 is existing technology. The main body 1 is a cuboid structure, with one side serving as a beam inlet surface 3. A mark 4, in the shape of a crosshair, is located at the center of one side of the main body 1 to mark the axis of the beam inlet surface 3. The main body 1 contains a set of slots extending to one side. The set of slots includes a first slot 5, a second slot 6, a third slot 7, and a fourth slot 8 arranged sequentially along the beam inlet surface 3 to the leveling nut 2. The first slot 5 is 17mm away from the beam inlet surface 3, the second slot 6 is 85mm away, the third slot 7 is 150mm away, and the fourth slot 8 is 210mm away. The slot assembly includes removable insert plates, the length of which is greater than the depth of the slot. One end of the insert plate located outside the main body 1 has an integrated connecting lug. The insert plates include a standard insert plate 9, a Markus ionization chamber adapter insert plate 10, and a Fammer ionization chamber adapter insert plate 11, all with the same external dimensions. The first slot 5, second slot 6, third slot 7, and fourth slot 8 have identical structures. The Markus ionization chamber adapter insert plate 10 has a groove for use with the Markus ionization chamber. The Fammer ionization chamber adapter insert plate 11 has a slot for use with the Fammer ionization chamber.

[0017] The implementation principle of the novel carbon ion radiotherapy dose calibration and testing phantom in this application is as follows: According to the internal settings of the carbon ion therapy planning system, the calibration depth of the radiation field is 21mm deep in water, the water equivalence coefficient of PMMA material is 1.16, the effective measurement depth of the Markus ionization chamber is 1.3mm, and the thickness of the front section of the calibration phantom is: 21-1.3 / 1.16=17mm, which is the thickness of the first slot from the beam inflow surface 3. During radiation field dose calibration, the Markus ionization chamber is placed in the Fammer ionization chamber adapter plate 11, with the front of the ionization chamber facing the beam inflow surface 3, and inserted into the first slot. The remaining three slots are filled with ordinary insert plates 9. Then, the phantom is placed in the measurement position as required, allowing for convenient and quick dose calibration of the planned radiation field.

[0018] Before each heavy ion therapy session, the physicist needs to perform quality control on the equipment. One of the quality control items is the heavy ion standard plan test. The purpose is to determine the accuracy of the machine's beam dose delivery by testing the planned point dose on a standard phantom. After scanning the phantom according to the positioning CT requirements, the data is transmitted to the planning system. Using this phantom image data, virtual target areas can be drawn at positions 6 (second slot), 7 (third slot), and 8 (fourth slot), and plans for the corresponding energy ranges can be created. The planning system calculates the physical dose at the corresponding measurement points as the standard reference value. During daily quality control, simply replace the ionization chamber and insert plate in the corresponding slots of the plan, and then place them at the beamline position to perform the standard plan measurement.

[0019] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A novel dose calibration and testing phantom for carbon ion radiotherapy, comprising a phantom body (1), wherein a leveling nut (2) is provided at one end of the phantom body (1), characterized in that: The main body of the mold (1) is a cuboid structure and one side of it is a beam inlet surface (3). A mark (4) for marking the axis of the beam inlet surface (3) is provided at the center of one side of the main body of the mold (1). The mark (4) is in the shape of a cross. The main body of the mold (1) is provided with a slot group extending to one side. The slot group is provided with a removable insert plate. The slot group includes a first slot (5), a second slot (6), a third slot (7) and a fourth slot (8) arranged sequentially along the beam inlet surface (3) to the leveling nut (2). The insert plate includes a common insert plate (9) with the same external dimensions, a Markus ionization chamber adapter insert plate (10) and a Fammer ionization chamber adapter insert plate (11). The first slot (5), the second slot (6) and the fourth slot (8) have the same structure.

2. The novel carbon ion radiotherapy dose calibration and testing phantom according to claim 1, characterized in that, The distance between the first slot (5) and the beam inlet surface (3) is 17mm, the distance between the second slot (6) and the beam inlet surface (3) is 85mm, the distance between the third slot (7) and the beam inlet surface (3) is 150mm, and the distance between the fourth slot (8) and the beam inlet surface (3) is 210mm.

3. The novel carbon ion radiotherapy dose calibration and testing phantom according to claim 1, characterized in that, The length of the insert plate is greater than the depth of the slot, and the end of the insert plate located outside the main body (1) is provided with an ear that is integral with the insert plate structure.

4. The novel carbon ion radiotherapy dose calibration and testing phantom according to claim 1, characterized in that, The Markus ionization chamber adapter plate (10) is provided with a groove for use with the Markus ionization chamber.

5. The novel carbon ion radiotherapy dose calibration and testing phantom according to claim 1, characterized in that, The Fammer ionization chamber adapter plate (11) is provided with a slot for use with the Fammer ionization chamber.

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