Ceramic substrate transmission type flat ionization chamber for monitoring dosage of medical linear accelerator

Abstract

The utility model relates to the technical field of accelerator dose detection, in particular to a ceramic substrate transmission type flat ionization chamber for monitoring dose of a medical linear accelerator, which comprises an upper ionization chamber and a lower ionization chamber, the upper ionization chamber and the lower ionization chamber have the same basic structure, and collectors of the upper ionization chamber and the lower ionization chamber share a ceramic substrate as a support. Wherein the upper ionization chamber is composed of an upper ionization chamber shell, an upper electrode laid on the inner side of the upper ionization chamber shell, an upper collector and a ceramic substrate for supporting the upper collector. The upper ionization chamber shell is provided with an incident transmission window, the lower ionization chamber shell is provided with an emergent transmission window, and the thickness of the emergent transmission window is properly increased; the ceramic substrate is used as a support, so that the flatness and the stability of the electrode plate are improved, and the performance drift caused by thermal shock is reduced; the O-shaped sealing ring is adopted to seal the air chamber, so that measurement errors caused by external temperature and air pressure changes can be reduced.

Description

Technical Field

[0001] The utility model relates to a flat plate ionization chamber, in particular to a ceramic substrate transmission type flat plate ionization chamber used for medical linear accelerator dose monitoring, belonging to the technical field of accelerator dose detection. Background Art

[0002] Medical linear accelerators generally use a gas-filled transmission ionization chamber to monitor the dose of the radiation beam. The electrode material of the currently common transmission ionization chamber is generally Kapton film (Kapton) plated with aluminum, and the insulation material is lightweight materials such as polyurethane, and is shielded and sealed with a metal shell. Siemens' ionization chamber is made of glass ceramic electrodes and is divided into 9 independently sealed cavities, using a brazing process.

[0003] However, if aluminum film is used as the electrode material, the performance drift caused by its insufficient flatness and thermal conductivity cannot be ignored. If glass ceramic is used, it has good flatness and high thermal conductivity, and is highly resistant to radio frequency breakdown. However, its brazing process requirements are high and the electrode lead-out method is complex. The dose error caused by backscatter caused by the opening and closing of the collimator (collimator) below the ionization chamber cannot be avoided. To solve this problem, medical accelerators generally place a layer of aluminum foil between the ionization chamber and the primary collimator below to reduce or eliminate backscatter, which increases the device space and complexity. Utility Model Content

[0004] The purpose of the present utility model is to provide a ceramic-based transmission-type flat-plate ionization chamber for dose monitoring of medical linear accelerators in order to solve the above-mentioned problems. The ceramic substrate is used as a support to improve the flatness and stability of the electrode plate and reduce the performance drift caused by thermal shock; the "O"-shaped sealing ring is used to seal the air chamber to reduce the measurement error caused by changes in external temperature and air pressure; by increasing the thickness of the output transmission window, the dose measurement error caused by backscattering caused by the lower-stage collimator can be reduced. The method is simple and effective.

[0005] The utility model achieves the above-mentioned purpose through the following technical solutions: a ceramic substrate transmission type flat plate ionization chamber for medical linear accelerator dose monitoring, comprising an upper ionization chamber and a lower ionization chamber, the basic structure of the two being the same, the collectors of the upper ionization chamber and the lower ionization chamber share a ceramic substrate as a support, wherein the upper ionization chamber is composed of an upper ionization chamber shell, an upper electrode applied on the inner side of the upper ionization chamber shell, an upper collector, and a ceramic substrate providing support for the upper collector, the bottom end of the upper ionization chamber shell contacts the ceramic substrate, and the two are sealed. The air chamber serves as the air chamber of the upper ionization chamber. The upper electrode on the inner side of the upper ionization chamber shell and the upper collector electrode on the ceramic substrate are both manufactured using a direct copper-clad ceramic substrate process. The bottom end of the ceramic substrate abuts against the lower ionization chamber shell. Grooves are provided on both the upper and lower ionization chamber shells. The same sealing ring is engaged in the two grooves. The sealing ring adopts an "O"-shaped sealing ring made of polytetrafluoroethylene material. An incident transmission window is installed on the upper ionization chamber shell, and an exit transmission window is installed on the lower ionization chamber shell. The thickness of the exit transmission window is appropriately increased.

[0006] Preferably, an incident transmission window is installed on the upper ionization chamber shell, and an exit transmission window is installed on the lower ionization chamber shell, and the thickness of the exit transmission window is greater than the thickness of the incident transmission window.

[0007] Preferably, the upper ionization chamber shell and the incident transmission window adopt an integrally formed structure, and the lower ionization chamber shell and the exit transmission window adopt an integrally formed structure.

[0008] Preferably, an upper electrode is installed at the bottom end of the incident transmission window, and a lower electrode is installed at the top end of the exit transmission window.

[0009] Preferably, the circuit lead-out portion on the ceramic substrate is designed to be made of FPC material, attached to the ceramic substrate and welded to the upper electrode and the lower electrode respectively.

[0010] Preferably, four upper collecting electrodes are installed on the top end of the ceramic substrate, and four lower collecting electrodes are installed on the bottom end of the ceramic substrate.

[0011] Preferably, the four upper collecting electrodes and the four lower collecting electrodes are symmetrical electrode plates designed in partitions, and the upper collecting electrodes and the lower collecting electrodes are both square structures.

[0012] Preferably, an electrode lead terminal is fixedly connected to the outer wall of the lower ionization chamber housing, and the electrode lead terminal is a 12-pin board-to-board connector. All electrode signals in the upper and lower ionization chambers are led to the electrode lead terminal on the same side.

[0013] Preferably, four bolts are rotatably connected to the upper ionization chamber shell, and the bolts are threadedly connected to the lower ionization chamber shell.

[0014] The beneficial effects of the present invention are as follows: the use of a direct copper-clad ceramic substrate process improves the flatness and stability of the electrode plate, and reduces performance drift caused by thermal shock, due to the advantages of ceramics such as high thermal conductivity, high resistance to radio frequency breakdown, low dielectric constant, and high hardness; the use of a polytetrafluoroethylene "O"-shaped sealing ring design is resistant to high-temperature corrosion, and compared to the ceramic brazing process, its design is simple and its sealing reliability is high; the electrode lead-out method uses an FPC method to connect the circuits inside and outside the ionization chamber cavity, which is simple in design and does not affect the sealing design. Compared with the previous ceramic drilling and welding electrode method, it is simple and practical; by increasing the thickness of the transmission window, the dose measurement error caused by backscatter is reduced, which is simple and effective. The aluminum foil used in the traditional method can be eliminated, and the measurement is more accurate and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0016] Figure 2 This is a schematic diagram of the connection structure between the upper ionization chamber shell and the bolts of the present invention;

[0017] Figure 3 This is a schematic diagram of the connection structure between the ceramic substrate and the upper collector of the present invention;

[0018] Figure 4 for Figure 3 The enlarged structural diagram of part A is shown;

[0019] Figure 5 for Figure 3 The enlarged structural diagram of part B is shown;

[0020] Figure 6 This is a schematic diagram of the connection structure between the upper ionization chamber shell and the sealing ring of the utility model.

[0021] In the figure: 1. upper ionization chamber; 101. upper ionization chamber shell; 102. incident transmission window; 103. upper electrode; 104. upper collecting electrode; 2. lower ionization chamber; 201. lower ionization chamber shell; 202. exit transmission window; 203. lower electrode; 204. lower collecting electrode; 3. ceramic substrate; 4. groove; 5. sealing ring; 6. electrode lead terminal; 7. bolt. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] See also Figure 1-6 As shown, a ceramic substrate transmission type flat-plate ionization chamber for medical linear accelerator dose monitoring includes an upper ionization chamber 1 and a lower ionization chamber 2. The two have the same basic structure. The collectors of the upper ionization chamber 1 and the lower ionization chamber 2 share a ceramic substrate 3 as a support, wherein the upper ionization chamber 1 is composed of an upper ionization chamber shell 101, an upper electrode 103 applied on the inner side of the upper ionization chamber shell 101, an upper collector 104 and a ceramic substrate 3 providing support for the upper collector 104. The bottom end of the upper ionization chamber shell 101 abuts against the ceramic substrate 3, and the air cavity formed by the two seals serves as the air chamber of the upper ionization chamber 1. The upper electrode 103 on the inner side of the upper ionization chamber shell 101 and the upper collector 104 on the ceramic substrate 3 are both made by direct copper cladding ceramic substrate technology. The bottom end of the ceramic substrate 3 abuts against the lower electrode The ionization chamber housing 201, the upper ionization chamber housing 101, and the lower ionization chamber housing 201 are all provided with grooves, and the same sealing ring 5 is engaged in the two grooves. The sealing ring 5 is an "O"-shaped sealing ring made of polytetrafluoroethylene material. The upper ionization chamber housing 101 is installed with an incident transmission window 102, and the lower ionization chamber housing 201 is installed with an exit transmission window 202. The thickness of the exit transmission window 202 is appropriately increased, and a ceramic substrate 3 is used as a support, which improves the flatness and stability of the electrode plate and reduces performance drift caused by thermal shock. The "O"-shaped sealing ring 5 is used to seal the gas chamber, which can reduce measurement errors caused by changes in external temperature and air pressure. By increasing the thickness of the exit transmission window 202, the dose measurement error caused by backscattering caused by the lower-stage collimator can be reduced. This method is simple and effective.

[0024] As a technical optimization solution of the present invention, an incident transmission window 102 is installed on the upper ionization chamber housing 101, and an exit transmission window 202 is installed on the lower ionization chamber housing 201. The thickness of the exit transmission window 202 is greater than that of the incident transmission window 102. The upper ionization chamber housing 101 and the incident transmission window 102 are integrally molded, while the lower ionization chamber housing 201 and the exit transmission window 202 are integrally molded. By increasing the thickness of the exit transmission window 202, the dose measurement error caused by backscattering caused by the lower collimator can be reduced. This method is simple and effective, eliminating the aluminum foil used in traditional methods and achieving higher accuracy and stability.

[0025] As a technical optimization solution of the present invention, an upper electrode 103 is installed at the bottom end of the incident transmission window 102, and a lower electrode 203 is installed at the top end of the exit transmission window 202. The circuit lead-out portion on the ceramic substrate 3 is designed to be made of FPC material, attached to the ceramic substrate 3 and welded to the upper electrode 103 and the lower electrode 203 respectively. Four upper collecting electrodes 104 are installed at the top end of the ceramic substrate 3, and four lower collecting electrodes 204 are installed at the bottom end of the ceramic substrate 3. An electrode lead-out terminal 6 is fixedly connected to the outer wall of the lower ionization chamber housing 201. The electrode lead-out terminal 6 is a 12-pin board-to-board connector. All electrode signals in the upper ionization chamber 1 and the lower ionization chamber 2 are led to the electrode lead-out terminal 6 on the same side, so that the entire device is in a stable operating state.

[0026] As a technical optimization solution of the present invention, the four upper collecting electrodes 104 and the four lower collecting electrodes 204 are all symmetrical plates with a partitioned design, and the upper collecting electrodes 104 and the lower collecting electrodes 204 are all square structures; the four upper collecting electrodes 104 and the four lower collecting electrodes 204 are all symmetrical plates with a partitioned design, and the purpose of designing them into square shapes is to strictly correspond to the shape of the beam, and the symmetry of the beam signal can be calculated through the signal sampling circuit.

[0027] As a technical optimization solution of the present invention, four bolts 7 are rotatably connected to the upper ionization chamber housing 101, and the bolts 7 are threadedly connected to the lower ionization chamber housing 201; the bolts 7 make the packaging of the upper ionization chamber 1 and the lower ionization chamber 2 more secure.

[0028] When the present invention is in use, the upper collector 104 and the lower collector 204 are mounted on the same ceramic substrate 3, and the required circuit is manufactured by the direct copper-clad ceramic substrate process, and the four upper collectors 104 and the four lower collectors 204 are all symmetrical plates with partitioned design. The purpose of designing them as square is to strictly correspond to the shape of the beam. Through the signal sampling circuit, the symmetry of the beam signal, such as the left-right support in the x-axis direction and the left-right symmetry in the y-axis direction, can be calculated to achieve the purpose of real-time monitoring of the signal. The electrode is manufactured by the direct copper-clad ceramic substrate process, which is mature and has high processing accuracy. Compared with the previous aluminum film coating process, the ceramic substrate 3 can provide stable and reliable support for the circuit, has good heat resistance, and is not easy to deform; the upper electrode 103 and the lower electrode 203 are also manufactured by the direct copper-clad ceramic substrate process, and all electrode signals are led out to the electrode lead terminal 6 on the same side, which is 12 A pin board-to-board connector is fixed on the side of the lower ionization chamber 2 for easy connection to the subsequent detection and control circuit; an O-shaped sealing ring 5 is used between the upper ionization chamber 1 and the lower ionization chamber 2. The sealing ring 5 is made of polytetrafluoroethylene material and has an operating temperature of up to 260 degrees Celsius, which can meet the sealing requirements of high-temperature working conditions. Compared with the previous ceramic brazing process, the operation difficulty is greatly reduced; the circuit lead-out part is designed to be made of FPC material, and the circuit is attached to the ceramic substrate 3 and welded to the upper electrode 103 and the lower electrode 203 respectively. Due to the good ductility of FPC, no abnormal conditions such as breakage will occur when the bearing sealing ring 5 is under pressure; by appropriately increasing the thickness of the output transmission window 202, the backscattering error can be effectively reduced. The thickness of the output transmission window 202 is designed to be 3 mm, which can be corrected according to the actual measurement method. The aluminum foil in the traditional method can be omitted, and it is more accurate and stable.

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0030] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A ceramic substrate transmission type flat plate ionization chamber for medical linear accelerator dose monitoring, comprising an upper ionization chamber (1), characterized in that: The upper ionization chamber (1) comprises an upper ionization chamber shell (101), an upper electrode (103) is applied on the inner side of the upper ionization chamber shell (101), the bottom end of the upper ionization chamber shell (101) abuts against a ceramic substrate (3), an upper collecting electrode (104) is applied on the ceramic substrate (3), the upper collecting electrode (104) is manufactured by a direct copper-clad ceramic substrate process, the bottom end of the ceramic substrate (3) abuts against a lower ionization chamber (2), the lower ionization chamber (2) comprises a lower ionization chamber shell (201), a lower electrode (203) is applied on the inner side of the lower ionization chamber shell (201), and the lower ionization chamber shell (201) is provided with a lower electrode (203). The top of the body (201) contacts the ceramic substrate (3), and a lower collecting electrode (204) is applied on the ceramic substrate (3). The upper ionization chamber shell (101) and the lower ionization chamber shell (201) are both provided with grooves (4). The same sealing ring (5) is engaged in the two grooves (4). The sealing ring (5) is an "O" type sealing ring made of polytetrafluoroethylene material. The upper ionization chamber shell (101) is provided with an incident transmission window (102), and the lower ionization chamber shell (201) is provided with a lower exit transmission window (202). The thickness of the exit transmission window (202) is appropriately increased.

2. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 1, characterized in that: An incident transmission window (102) is installed on the upper ionization chamber housing (101), and an exit transmission window (202) is installed on the lower ionization chamber housing (201). The thickness of the exit transmission window (202) is greater than that of the incident transmission window (102).

3. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 2, characterized in that: The upper ionization chamber housing (101) and the incident transmission window (102) adopt an integrally formed structure, and the lower ionization chamber housing (201) and the exit transmission window (202) adopt an integrally formed structure.

4. The ceramic substrate transmission type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 3, characterized in that: An upper electrode (103) is installed at the bottom end of the incident transmission window (102), and a lower electrode (203) is installed at the top end of the exit transmission window (202).

5. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 4, characterized in that: The circuit lead-out portion on the ceramic substrate (3) is designed to be made of FPC material, is attached to the ceramic substrate (3), and is welded to the upper electrode (103) and the lower electrode (203) respectively.

6. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 5, characterized in that: Four upper collecting electrodes (104) are installed on the top end of the ceramic substrate (3), and four lower collecting electrodes (204) are installed on the bottom end of the ceramic substrate (3).

7. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 6, characterized in that: The four upper collecting electrodes (104) and the four lower collecting electrodes (204) are all symmetrical electrode plates designed in partitions, and the upper collecting electrodes (104) and the lower collecting electrodes (204) are all in a square structure.

8. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 1, characterized in that: An electrode lead-out terminal (6) is fixedly connected to the outer wall of the lower ionization chamber housing (201), and the electrode lead-out terminal (6) is a 12-pin board-to-board connector. All electrode signals in the upper ionization chamber (1) and the lower ionization chamber (2) are led to the electrode lead-out terminal (6) on the same side.

9. The ceramic-based transmission-type flat-plate ionization chamber for medical linear accelerator dose monitoring according to claim 8, characterized in that: Four bolts (7) are rotatably connected to the upper ionization chamber housing (101), and the bolts (7) are threadedly connected to the lower ionization chamber housing (201).

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