Morning check instrument for daily detection of medical linear accelerator and manufacturing method and application of morning check instrument

Abstract

The invention discloses a morning check instrument for daily detection of a medical linear accelerator, and the morning check instrument comprises a housing, a first group of multi-wire ionization chambers, a second group of multi-wire ionization chambers, a PMMA plate, a third group of multi-wire ionization chambers, and a fourth group of multi-wire ionization chambers, each group of multi-wire ionization chambers is composed of an anode circuit board and a cathode circuit board, and is connected with a data collection card. In addition, the invention further discloses preparation and application of the morning detection instrument, the metal anode electrode strip and the metal cathode electrode strip are etched by adopting a gold immersion process, the morning detection instrument is assembled, and the morning detection instrument is used for daily detection of the medical linear accelerator. According to the morning check instrument, four groups of multi-wire ionization chambers are used as probes, hospital technicians are rapidly, accurately and conveniently helped to complete daily morning check of the linear accelerator, the morning check instrument is easy to process and manufacture and relatively low in cost, GTLR errors are within + / -3%, CAX and BQF errors are within + / -7% when the medical linear accelerator is detected, and the effect is excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of gas detectors, and in particular relates to a morning inspection instrument for daily inspection of a medical linear accelerator, and a manufacturing method and application thereof. Background Art

[0002] Medical linear accelerator is a particle accelerator used in biology for radiotherapy of tumors. Medical linear accelerator is used to achieve sufficient and accurate treatment dose to the tumor area to improve the local control rate of the tumor and reduce radiation complications of normal tissues.

[0003] The complexity of the medical linear accelerator system determines that the probability of failure of the medical linear accelerator is much greater than that of other medical equipment. In order to ensure the quality control and quality assurance of radiotherapy, it is particularly important to strengthen the daily inspection of the medical linear accelerator. The relevant equipment must be inspected daily according to the regulations to ensure that the equipment characteristics do not deviate significantly from the benchmark values ​​obtained during acceptance and debugging.

[0004] Traditional morning check-up instruments use several or dozens of ionization chambers with outer walls as probes, which have high processing costs and the position resolution is limited by the volume and number of ionization chambers.

[0005] Therefore, there is a need for a morning inspection instrument for daily inspection of a medical linear accelerator, and a manufacturing method and application thereof. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a morning inspection instrument for daily inspection of medical linear accelerators in view of the deficiencies of the above-mentioned prior art. The morning inspection instrument uses four groups of multi-wire ionization chambers as probes, so that the electric field inside the multi-wire ionization chamber is uniform and stable, and the energy resolution of the multi-wire ionization chamber is improved. When the high-energy rays output by the medical linear accelerator pass through the multi-wire ionization chamber, the ionization effect ionizes the air sealed in the multi-wire ionization chamber and is collected by the multi-wire ionization chamber, thereby forming an ionization current signal, which helps hospital technicians to complete the daily morning inspection of the linear accelerator quickly, accurately and conveniently, and at a low cost.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a morning inspection instrument for daily detection of medical linear accelerators, characterized in that the morning inspection instrument includes a shell, and the inside of the shell is sequentially arranged from top to bottom with a first group of multi-wire ionization chambers, a second group of multi-wire ionization chambers, a PMMA plate, a third group of multi-wire ionization chambers and a fourth group of multi-wire ionization chambers, the first group of multi-wire ionization chambers includes a rectangular anode circuit board and a rectangular cathode circuit board arranged at intervals above and below, the second group of multi-wire ionization chambers, the third group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers are all the same as the first group of multi-wire ionization chambers in structure, the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the third group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers are respectively connected to a multi-channel data acquisition card with signal lines, and the shell is also provided with a display screen connected to the data acquisition card.

[0008] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that the anode circuit board is a printed circuit board with 10 to 20 mutually parallel metal anode electrode strips etched on one side, the width of the metal anode electrode strip is 100μm to 1000μm, and the spacing between adjacent metal anode electrode strips is 15mm to 20mm; the cathode circuit board is a printed circuit board with 10 to 20 mutually parallel metal cathode electrode strips etched on one side, the width of the metal cathode electrode strip is 100μm to 1000μm, and the spacing between adjacent metal cathode electrode strips is 1mm to 5mm.

[0009] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that the direction of the metal cathode electrode strips in each of the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the third group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers is the same as the direction of the metal anode electrode strips, the direction of the metal anode electrode strips in the first group of multi-wire ionization chambers is the same as the direction of the metal anode electrode strips in the third group of multi-wire ionization chambers, and is perpendicular to the direction of the metal cathode electrode strips in the second group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers.

[0010] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that the metal anode electrode strips in the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the third group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers are all connected to a positive high voltage of 400V to 600V, and the metal cathode electrode strips are all grounded.

[0011] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that four nylon studs are arranged on the top of the inner part of the shell, and the four corners of the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the PMMA plate, the third group of multi-wire ionization chambers, and the fourth group of multi-wire ionization chambers are respectively connected in series through four nylon screws, and the ends of the nylon screws extending from the first group of multi-wire ionization chambers are connected to the nylon studs.

[0012] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that the distances between the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the PMMA plate, the third group of multi-wire ionization chambers, and the fourth group of multi-wire ionization chambers are all 2mm to 4mm.

[0013] The above-mentioned morning inspection instrument for daily inspection of medical linear accelerators is characterized in that air is stored in the shell as a working gas, and the upper surface of the shell is printed with crosshairs corresponding to the positions of the first group of multi-filament ionization chambers.

[0014] In addition, the present invention also proposes a method for preparing a morning inspection instrument for daily inspection of a medical linear accelerator, characterized in that the method comprises the following steps:

[0015] Step 1: Prepare four anode circuit boards and four cathode circuit boards by etching through an immersion gold process;

[0016] Step 2: assembling the four anode circuit boards and the four cathode circuit boards prepared in step 1 into a first group of multi-filament ionization chambers, a second group of multi-filament ionization chambers, a third group of multi-filament ionization chambers, and a fourth group of multi-filament ionization chambers respectively;

[0017] Step three, the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the third group of multi-wire ionization chambers, and the fourth group of multi-wire ionization chambers obtained in step two are sequentially arranged on a nylon screw, and a PMMA plate is arranged between the second group of multi-wire ionization chambers and the third group of multi-wire ionization chambers, and then the nylon screw is connected with the nylon stud to obtain a morning inspection instrument for daily inspection of medical linear accelerators.

[0018] In addition, the present invention also proposes an application of a morning inspection instrument for daily inspection of a medical linear accelerator, characterized in that the application includes the following process: the morning inspection instrument is placed at the isocenter position on the treatment bed of the medical linear accelerator according to the crosshairs on the outer shell, and the direction of the metal cathode electrode strips in the first group of multi-wire ionization chambers is perpendicular to the direction of the medical linear accelerator gun and target, and then the medical linear accelerator is made to emit a beam with an output dose of 200MU, and then the morning inspection instrument is used to detect the flatness, symmetry, central axis dose and dose rate of the medical linear accelerator, so as to perform daily inspection on the medical linear accelerator.

[0019] The isocenter position in the present invention is a virtual point in space, which is represented by the cross emitted by three groups of "laser positioning lights" on the radiation wall. This point is the intersection of the rotation axes of the frame, radiation head and treatment bed. No matter how these three rotate, this point is the radiation midpoint, so it is called the isocenter position, which corresponds to the center origin of the treatment bed. The test results obtained at this position are more accurate.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention uses four groups of multi-wire ionization chambers as probes, so that the electric field inside the multi-wire ionization chamber is uniform and stable, and the energy resolution of the multi-wire ionization chamber is improved. When the high-energy rays output by the medical linear accelerator pass through the multi-wire ionization chamber, the ionization effect causes the air sealed in the multi-wire ionization chamber to be ionized and collected by the multi-wire ionization chamber, thereby forming an ionization current signal, which helps hospital technicians to complete the daily morning inspection of the linear accelerator quickly, accurately and conveniently, and the cost is low.

[0022] 2. The present invention controls the directions of metal anode electrode strips in four groups of multi-wire ionization chambers to form two pairs of detector groups in the X direction and the Y direction. The directions of the metal anode electrode strips in each pair of the detector groups in the X direction and the Y direction are perpendicular to each other and interwoven into a detector grid. The number of detection points is controlled by controlling the number of metal anode electrode strips, so that the electric field is more uniform and stable, thereby reducing the fluctuation of the anode signal amplitude and improving the energy resolution of the multi-wire ionization chamber. At the same time, the dead zone of the electric field distortion in the edge area of ​​the multi-wire ionization chamber is relatively reduced, thereby increasing the sensitive volume of the multi-wire ionization chamber.

[0023] 3. The present invention adopts the gold immersion process to etch the printed circuit boards with metal anode electrode strips and metal cathode electrode strips as the anode circuit board and cathode circuit board respectively. The anode circuit board is easy to process and manufacture, and the cost is relatively low, which reduces the difficulty of electrode processing and manufacturing.

[0024] 4. The present invention uses nylon screws to connect four groups of multi-wire ionization chambers and a housing, adjusts the distance between each group of multi-wire ionization chambers and between each group of multi-wire ionization chambers and the PMMA plate by replacing plastic bolts, and adjusts the distance between the anode circuit board and the cathode circuit board in each group of multi-wire ionization chambers by nylon gaskets, thereby adjusting the electric field strength of the multi-wire ionization chamber. It is easy to optimize and adjust the internal electric field structure of the multi-wire ionization chamber and is suitable for different needs.

[0025] 5. The present invention uses a multi-channel data acquisition card to analyze the data collected by four groups of multi-wire ionization chambers, and the obtained flatness, symmetry, central axis dose and dose rate results are displayed in real time on the display screen, which is convenient for detection personnel to observe and record.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic structural diagram of a morning inspection instrument for daily inspection of a medical linear accelerator.

[0028] Figure 2 The present invention is a schematic diagram of the internal structure of a morning inspection instrument used for daily inspection of a medical linear accelerator.

[0029] Figure 3 It is a schematic diagram of the positional relationship of the first group of multi-wire ionization chambers, the second group of multi-wire ionization chambers, the PMMA plate, the third group of multi-wire ionization chambers and the fourth group of multi-wire ionization chambers of the present invention.

[0030] Figure 4 It is a schematic structural diagram of the case where there are 10 metal anode electrode strips on the anode circuit board of the first group of multi-filament ionization chambers of the present invention.

[0031] Figure 5 This is a detection point distribution diagram of the morning inspection instrument used for daily inspection of a medical linear accelerator of the present invention when there are 11 metal cathode electrode strips.

[0032] Figure 6 This is a graph showing the test results of the first day of the morning inspection instrument used for routine inspection of a medical linear accelerator in Example 3 of the present invention.

[0033] Figure 7 This is a graph showing the test results of the morning inspection instrument used for routine inspection of medical linear accelerators on the second day in Example 3 of the present invention.

[0034] Figure 8 This is a graph showing the test results of the morning inspection instrument used for daily inspection of a medical linear accelerator on the third day in Example 3 of the present invention.

[0035] Fig. 9 This is a graph showing the result of the fourth day of testing of the morning inspection instrument used for daily testing of medical linear accelerators in Example 3 of the present invention.

[0036] Description of reference numerals:

[0037] 1—housing; 2—first set of multi-wire ionization chambers; 3—second set of multi-wire ionization chambers;

[0038] 4—PMMA plate; 5—third group of multi-wire ionization chamber; 6—fourth group of multi-wire ionization chamber;

[0039] 7—nylon screw; 8—nylon stud; 9—anode circuit board;

[0040] 10—cathode circuit board; 11—display screen; 12—metal anode electrode strip. DETAILED DESCRIPTION

[0041] A morning inspection instrument for daily inspection of a medical linear accelerator of the present invention is described in detail through Example 1.

[0042] Example 1

[0043] like Figure 1 to Figure 3As shown, the morning inspection instrument for daily inspection of medical linear accelerators of this embodiment includes a shell 1, and a first group of multi-wire ionization chambers 2, a second group of multi-wire ionization chambers 3, a PMMA plate 4, a third group of multi-wire ionization chambers 5 and a fourth group of multi-wire ionization chambers 6 are arranged in sequence from top to bottom inside the shell 1, the first group of multi-wire ionization chambers 2 includes a rectangular anode circuit board 9 and a rectangular cathode circuit board 10 arranged at intervals above and below, the second group of multi-wire ionization chambers 3, the third group of multi-wire ionization chambers 5 and the fourth group of multi-wire ionization chambers 6 are all the same as the first group of multi-wire ionization chambers 2 in structure, the first group of multi-wire ionization chambers 2, the second group of multi-wire ionization chambers 3, the third group of multi-wire ionization chambers 5 and the fourth group of multi-wire ionization chambers 6 are respectively connected to a multi-channel data acquisition card with signal lines, and a display screen 11 connected to the data acquisition card is also provided on the shell 1.

[0044] It should be noted that the morning inspection instrument uses four groups of multi-wire ionization chambers as probes. By grounding the cathode circuit board 10 in each group of multi-wire ionization chambers and connecting the anode circuit board 9 to a positive voltage, a strong electric field is formed between the cathode circuit board 10 and the anode circuit board 9. The charged particles generated by the medical linear accelerator pass through the outer shell 1 and enter the four groups of multi-wire ionization chambers in turn, and ionize the air in the first group of multi-wire ionization chambers 2, the second group of multi-wire ionization chambers 3, the third group of multi-wire ionization chambers 5, and the fourth group of multi-wire ionization chambers 6 to generate electron ion pairs. The drift of electrons between the cathode circuit board 10 and the anode circuit board 9 will generate an induction signal on the anode circuit board 9. The anode circuit board 9 and the cathode circuit board 10 together form a group of multi-wire ionization chamber signal generation and collection areas. When the high-energy rays output by the accelerator pass through the multi-wire ionization chamber, the ionization effect causes the multi-wire ionization chamber to generate electron ion pairs. The sealed air in the filament ionization chamber is ionized, and the generated electron ion pairs, i.e., positive ions and electrons, move in a directional manner under the action of an external electric field, i.e., electrons move toward the positive plate and positive ions move toward the negative plate, and are collected by the multi-wire ionization chamber to form an ionization current signal. The signal pulse amplitude is related to the ionization position and orientation. Therefore, compared with traditional ionization chambers, multi-wire ionization chambers have better position resolution and are widely used in measuring particle energy. In addition, since the multi-wire ionization chamber has a large output pulse amplitude, in order to ensure that its position resolution meets the requirements, the structure of the multi-wire ionization chamber is required to be high, so as to solve the problem of high cost of existing detectors used for daily detection of medical linear accelerators. The morning inspection instrument helps hospital technicians complete daily morning inspections of linear accelerators quickly, accurately and conveniently, and at a low cost.

[0045] It should be noted that the data collected by the four groups of multi-wire ionization chambers are analyzed by a multi-channel data acquisition card, and then the test results are directly displayed on the display screen 11.

[0046] It should be noted that the four groups of multi-wire ionization chambers are stacked and a PMMA plate 4 is added in the middle to achieve dose construction, which is beneficial for reading radiation quality data.

[0047] It should be noted that the material of the housing 1 is polyethylene.

[0048] like Figure 4 As shown, in this embodiment, the anode circuit board 9 is a printed circuit board with 10 to 20 mutually parallel metal anode electrode strips 12 etched on one side, the width of the metal anode electrode strip 12 is 100 μm to 1000 μm, and the spacing between adjacent metal anode electrode strips 12 is 15 mm to 20 mm; the cathode circuit board 10 is a printed circuit board with 10 to 20 mutually parallel metal cathode electrode strips etched on one side, the width of the metal cathode electrode strip is 100 μm to 1000 μm, and the spacing between adjacent metal cathode electrode strips is 1 mm to 5 mm.

[0049] It should be noted that the number of metal anode electrode strips 12 should not be too many or too few. Too many will make processing difficult and the working voltage of the multi-wire ionization chamber will have to be increased. Too few will result in too few points being detectable, affecting the function of the morning inspection instrument.

[0050] It should be noted that the anode circuit board 9 and cathode circuit board 10 used in the four sets of multi-wire ionization chambers are etched with a metal anode electrode strip 12 using an immersion gold process. The use of the immersion gold process during etching can ensure that the surface flatness of the metal anode electrode strip 12 is better, which is more conducive to charge collection.

[0051] It should be noted that by controlling the parameters of the anode circuit board 9 and the cathode circuit board 10, compared with the metal ring field cage and the metal wire field cage, it has the advantages of simple production, mature technology, and guaranteed parallelism and width of the surface metal electrodes.

[0052] It should be noted that the number of metal anode electrode strips 12 on the anode circuit board 9 is preferably 10, 15 or 20, the width of the metal anode electrode strip 12 is preferably 100μm, 500μm or 1000μm, and the spacing between adjacent metal anode electrode strips 12 is preferably 15mm, 18mm or 20mm. The number of metal cathode electrode strips on the cathode circuit board 10 is preferably 10, 15 or 20, the width of the metal cathode electrode strip is preferably 100μm, 500μm or 1000μm, and the spacing between adjacent metal cathode electrode strips is preferably 1mm, 3mm or 5mm.

[0053] In this embodiment, the direction of the metal cathode electrode strips in each of the first group of multi-filament ionization chambers 2, the second group of multi-filament ionization chambers 3, the third group of multi-filament ionization chambers 5 and the fourth group of multi-filament ionization chambers 6 is the same as the direction of the metal anode electrode strips 12, the direction of the metal anode electrode strips 12 in the first group of multi-filament ionization chambers 2 is the same as the direction of the metal anode electrode strips 12 in the third group of multi-filament ionization chambers 5, and is perpendicular to the direction of the metal cathode electrode strips in the second group of multi-filament ionization chambers 3 and the fourth group of multi-filament ionization chambers 6.

[0054] It should be noted that the first group of multi-filament ionization chambers 2 and the second group of multi-filament ionization chambers 3 form a first pair of detector groups in the X direction and the Y direction, and the third group of multi-filament ionization chambers 5 and the fourth group of multi-filament ionization chambers 6 form a second pair of detector groups in the X direction and the Y direction. For each pair of detector groups in the X transverse direction and the Y longitudinal direction, each high-voltage electrode, that is, the metal anode electrode strip 12, represents a "detection line", and the "detection lines" in the X direction and the Y direction are interwoven into a detector grid, such as Figure 5 As shown, Figure 5 X0, X2, etc. represent the metal anode electrode strips 12 in the X transverse direction of the first group of multi-wire ionization chambers 2, and Y0, Y2, etc. represent the second group of multi-wire ionization chambers 3 in the Y longitudinal direction of the second group of multi-wire ionization chambers 3. Each intersection is a "detection point". The entire detection unit has a total of 100 to 400 "detection points", which are equivalent to 100 to 400 micro-detectors. By connecting an independent channel of a multi-channel data acquisition card to the signal lead-out terminal of each detection line, the signal amplitude collected by each channel is analyzed to determine the flatness, symmetry, radiation quality, and central axis dose stability of the accelerator radiation field. This staggered structure in the X and Y directions makes the electric field more uniform and stable, thereby reducing the signal amplitude fluctuation of the anode and improving the energy resolution of the multi-wire ionization chamber. At the same time, the dead zone of the electric field distortion in the edge of the multi-wire ionization chamber is relatively reduced, thereby increasing the sensitive volume of the multi-wire ionization chamber.

[0055] In this embodiment, the metal anode electrode strips 12 in the first group of multi-filament ionization chambers 2, the second group of multi-filament ionization chambers 3, the third group of multi-filament ionization chambers 5 and the fourth group of multi-filament ionization chambers 6 are all connected to a positive high voltage of 400V to 600V, and the metal cathode electrode strips are all grounded. Positive ions are extracted by grounding, and ionized electrons are collected by connecting to a positive high voltage.

[0056] It should be noted that the metal anode electrode strip 12 is preferably connected to a positive high voltage of 400V, 500V or 600V.

[0057] like Figure 2 As shown, in this embodiment, four nylon studs 8 are arranged on the top of the inner part of the housing 1, and the four corners of the first group of multi-filament ionization chambers 2, the second group of multi-filament ionization chambers 3, the PMMA plate 4, the third group of multi-filament ionization chambers 5, and the fourth group of multi-filament ionization chambers 6 are respectively connected in series through four nylon screws 7, and the ends of the nylon screws 7 extending from the first group of multi-filament ionization chambers 2 are connected to the nylon studs 8.

[0058] It should be noted that common plastic bolts are used between the first group of multi-filament ionization chambers 2, the second group of multi-filament ionization chambers 3, the PMMA board 4, the third group of multi-filament ionization chambers 5 and the fourth group of multi-filament ionization chambers 6, passing through the mounting holes of each layer of circuit boards and the PMMA board 4, and serving as connectors to fix each layer of circuit boards and the PMMA board 4 with the nylon screw 7. By replacing the plastic bolts, the distance between each group of multi-filament ionization chambers and between the chambers and the PMMA board 4 can be adjusted, and the distance between the anode circuit board 9 and the cathode circuit board 10 in each group of multi-filament ionization chambers can be adjusted through nylon gaskets.

[0059] In this embodiment, the distances between the first group of multi-wire ionization chambers 2 , the second group of multi-wire ionization chambers 3 , the PMMA plate 4 , the third group of multi-wire ionization chambers 5 , and the fourth group of multi-wire ionization chambers 6 are all 2 mm to 4 mm.

[0060] It should be noted that the distances between the first group of multi-wire ionization chambers 2 , the second group of multi-wire ionization chambers 3 , the PMMA plate 4 , the third group of multi-wire ionization chambers 5 , and the fourth group of multi-wire ionization chambers 6 are preferably 2 mm, 3 mm, or 4 mm.

[0061] like Figure 1 As shown, in this embodiment, air is stored in the housing 1 as the working gas, and a crosshair corresponding to the position of the first group of multi-filament ionization chambers 2 is printed on the upper surface of the housing 1. By marking the positions of multiple groups of multi-filament ionization chambers with the crosshairs printed on them, the center positions of the multiple groups of multi-filament ionization chambers are located, thereby ensuring accurate detection results.

[0062] The preparation method of a morning inspection instrument for daily inspection of a medical linear accelerator of the present invention is described in detail through Example 2.

[0063] Example 2

[0064] This embodiment includes the following steps:

[0065] Step 1: Prepare four anode circuit boards 9 and four cathode circuit boards 10 by etching with a gold immersion process;

[0066] Step 2: assemble the four anode circuit boards 9 and the four cathode circuit boards 10 prepared in step 1 into a first group of multi-filament ionization chambers 2, a second group of multi-filament ionization chambers 3, a third group of multi-filament ionization chambers 5, and a fourth group of multi-filament ionization chambers 6 respectively;

[0067] Step three, the first group of multi-wire ionization chambers 2, the second group of multi-wire ionization chambers 3, the third group of multi-wire ionization chambers 5, and the fourth group of multi-wire ionization chambers 6 obtained in step two are sequentially arranged on the nylon screw 7, and a PMMA plate 4 is arranged between the second group of multi-wire ionization chambers 3 and the third group of multi-wire ionization chambers 5, and then the nylon screw 7 is connected with the nylon stud 8 to obtain a morning inspection instrument for daily inspection of medical linear accelerators.

[0068] The application of a morning inspection instrument for daily inspection of a medical linear accelerator of the present invention is described in detail through Example 3.

[0069] Example 3

[0070] This embodiment includes the following steps:

[0071] Step 1. Move the morning inspection instrument to the isocenter position on the treatment bed of the Varian TrueBeam medical linear accelerator according to the crosshairs on the shell 1, and the direction of the metal cathode electrode strips in the first group of multi-wire ionization chambers 2 is perpendicular to the direction of the medical linear accelerator gun and target. Air is used as the working gas, and the metal anode electrode strips 12 are all connected to a positive high voltage of 500V. Then the medical linear accelerator emits a beam with an output dose of 200MU. X-rays pass through the morning inspection instrument shell 1 and enter the sensitive area of ​​the multi-wire ionization chamber. Then use the morning inspection instrument to detect the flatness, symmetry, central axis dose and dose rate of the medical linear accelerator within 4 days, read the GT\LR direction flatness and symmetry of the field, the central axis dose CAX, and the radiation quality BQF. The data are kept within the allowable error range. The GT\LR errors are both within ±3%, and the CAX and BQF errors are both within ±7%. The daily inspection of the medical linear accelerator is completed.

[0072] Figure 6 This is a result diagram of the first day's test of the morning inspection instrument used for daily inspection of a medical linear accelerator in this embodiment. Figure 7 This is a result diagram of the test on the second day of the morning inspection instrument used for daily inspection of the medical linear accelerator in this embodiment. Figure 8 This is a result diagram of the third day of testing of the morning inspection instrument used for daily testing of medical linear accelerators in this embodiment. Fig. 9 This is a graph showing the test result of the morning inspection instrument used for routine inspection of medical linear accelerators on the fourth day of the test in this embodiment. The horizontal axis is the number of tests, and the vertical axis is the measured GT\LR, CAX\BQF display values. 2 / ndf indicates the degree of deviation of the data from the average value. The smaller the value, the more stable the data. p0 indicates the average value obtained by data fitting. In the right box, GT indicates the symmetry of the accelerator gun target direction, LR indicates the symmetry of the accelerator in the left and right directions, BQF indicates the accelerator beam quality, and CAX indicates the accelerator central axis dose. Figure 6 to Figure 9 It can be seen that the GT\LR errors are within ±3%, and the CAX and BQF errors are within ±7%, which meets the requirements.

[0073] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A morning inspection instrument for daily inspection of medical linear accelerators. It is characterized in that The morning check-up instrument comprises a shell (1), wherein a first group of multi-filament ionization chambers (2), a second group of multi-filament ionization chambers (3), a PMMA plate (4), a third group of multi-filament ionization chambers (5) and a fourth group of multi-filament ionization chambers (6) are arranged in sequence from top to bottom inside the shell (1); the first group of multi-filament ionization chambers (2) comprises a rectangular anode circuit board (9) and a rectangular cathode circuit board (10) arranged in an upper and lower interval; the second group of multi-filament ionization chambers (3), the third group of multi-filament ionization chambers (5) and the fourth group of multi-filament ionization chambers (6) have the same structure as the first group of multi-filament ionization chambers (2); the first group of multi-filament ionization chambers (2), the second group of multi-filament ionization chambers (3), the third group of multi-filament ionization chambers (5) and the fourth group of multi-filament ionization chambers (6) are respectively connected to a multi-channel data acquisition card by signal lines; and a display screen (11) connected to the data acquisition card is also arranged on the shell (1).

2. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 1, It is characterized in that The anode circuit board (9) is a printed circuit board with 10 to 20 mutually parallel metal anode electrode strips (12) etched on one side, the width of the metal anode electrode strips (12) is 100 μm to 1000 μm, and the spacing between adjacent metal anode electrode strips (12) is 15 mm to 20 mm; the cathode circuit board (10) is a printed circuit board with 10 to 20 mutually parallel metal cathode electrode strips etched on one side, the width of the metal cathode electrode strips is 100 μm to 1000 μm, and the spacing between adjacent metal cathode electrode strips is 1 mm to 5 mm.

3. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 2, It is characterized in that The direction of the metal cathode electrode strips in each of the first group of multi-filament ionization chambers (2), the second group of multi-filament ionization chambers (3), the third group of multi-filament ionization chambers (5) and the fourth group of multi-filament ionization chambers (6) is the same as the direction of the metal anode electrode strips (12); the direction of the metal anode electrode strips (12) in the first group of multi-filament ionization chambers (2) is the same as the direction of the metal anode electrode strips (12) in the third group of multi-filament ionization chambers (5), and is perpendicular to the direction of the metal cathode electrode strips in the second group of multi-filament ionization chambers (3) and the fourth group of multi-filament ionization chambers (6).

4. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 2, It is characterized in that The metal anode electrode strips (12) in the first group of multi-filament ionization chambers (2), the second group of multi-filament ionization chambers (3), the third group of multi-filament ionization chambers (5) and the fourth group of multi-filament ionization chambers (6) are all connected to a positive high voltage of 400V to 600V, and the metal cathode electrode strips are all grounded.

5. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 1, It is characterized in that Four nylon studs (8) are arranged at the top of the interior of the housing (1); the four corners of the first group of multi-filament ionization chambers (2), the second group of multi-filament ionization chambers (3), the PMMA plate (4), the third group of multi-filament ionization chambers (5), and the fourth group of multi-filament ionization chambers (6) are respectively connected in series via four nylon screws (7); the ends of the nylon screws (7) extending out of the first group of multi-filament ionization chambers (2) are connected to the nylon studs (8).

6. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 1, It is characterized in that The distances between the first group of multi-wire ionization chambers (2), the second group of multi-wire ionization chambers (3), the PMMA plate (4), the third group of multi-wire ionization chambers (5), and the fourth group of multi-wire ionization chambers (6) are all 2 mm to 4 mm.

7. A morning inspection instrument for daily inspection of medical linear accelerators according to claim 1, It is characterized in that Air is stored in the housing (1) as a working gas, and a crosshair corresponding to the position of the first group of multi-filament ionization chambers (2) is printed on the upper surface of the housing (1).

8. A method for preparing a morning inspection instrument for daily inspection of a medical linear accelerator as claimed in any one of claims 1 to 7, It is characterized in that The method comprises the following steps: Step 1: Prepare four anode circuit boards (9) and four cathode circuit boards (10) by etching using a gold immersion process; Step 2: assembling the four anode circuit boards (9) and the four cathode circuit boards (10) prepared in step 1 into a first group of multi-filament ionization chambers (2), a second group of multi-filament ionization chambers (3), a third group of multi-filament ionization chambers (5), and a fourth group of multi-filament ionization chambers (6); Step 3: The first group of multi-filament ionization chambers (2), the second group of multi-filament ionization chambers (3), the third group of multi-filament ionization chambers (5), and the fourth group of multi-filament ionization chambers (6) obtained in step 2 are sequentially arranged on a nylon screw (7), and a PMMA plate (4) is arranged between the second group of multi-filament ionization chambers (3) and the third group of multi-filament ionization chambers (5), and then the nylon screw (7) is connected to a nylon stud (8), so as to obtain a morning inspection instrument for daily inspection of a medical linear accelerator.

9. An application of a morning inspection instrument for daily inspection of a medical linear accelerator as claimed in any one of claims 1 to 7, It is characterized in that The application includes the following process: the morning inspection instrument is moved to the isocenter position on the treatment bed of the medical linear accelerator according to the crosshairs on the shell (1), and the direction of the metal cathode electrode strips in the first group of multi-wire ionization chambers (2) is perpendicular to the direction of the medical linear accelerator gun and target, and then the medical linear accelerator is made to emit a beam with an output dose of 200MU, and then the morning inspection instrument is used to detect the flatness, symmetry, central axis dose and dose rate of the medical linear accelerator, so as to perform daily inspection on the medical linear accelerator.

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