A pulse X-ray reference radiation field generating device based on a pulse X-ray machine

Abstract

The present invention relates to a pulse X-ray reference radiation field generating device based on a pulse X-ray machine, belonging to the field of pulse radiation testing technology, including a pulse X-ray machine for radiodiagnosis, wherein the exit port of the pulse X-ray machine for radiodiagnosis is provided with a Be window and a built-in aperture, and an additional filtering device, a collimating aperture and a monitoring ionization chamber are sequentially provided along the axis of the X-ray radiation field generated by the pulse X-ray machine for radiodiagnosis; the millisecond-level pulse X-rays generated by the pulse X-ray machine for radiodiagnosis are emitted from the Be window and the built-in aperture, and are filtered by the additional filtering device to form a pulsed filtered beam X-ray, which is then collimated by the collimating aperture to form a millisecond-level pulse X-ray reference radiation field. The pulse X-ray reference radiation field device provided by the present invention can realize the radiation performance parameter test of the nuclear radiation dosimeter under the pulse dynamic part and the nuclear critical accident alarm system test, etc., and solve the traceability problem of the measuring instrument for pulse radiation dose monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of pulse radiation testing, and in particular relates to a pulse X-ray reference radiation field generating device based on a pulse X-ray machine. Background Art

[0002] International research on radiation protection dosimetry is mainly focused on continuous radiation, but pulsed radiation has been widely used in industrial flaw detection, X-ray diagnosis and scientific research. Pulsed radiation has a wide range of applications in nuclear technology fields such as the development of new detectors, pulsed ionizing radiation measurement, transient imaging and nuclear accident emergency response.

[0003] Active electronic dosimeters are widely used for dose monitoring of ionizing radiation. Their direct-reading display and alarm functions provide important monitoring methods for radiation practitioners. Active electronic dosimeters are divided into many types based on radiation detection methods, including GM counter type, scintillator detector type, semiconductor detector type and ionization chamber type, with real-time display and dose alarm functions. Pulsed X-rays have the characteristics of short duration and high instantaneous dose rate, and their radiation dose measurement is extremely difficult. Taking ns-level radiation pulses as an example, the single pulse dose often reaches more than 1μSv, and the instantaneous dose rate can reach 10 5 Sv / h or more. For GM counters, semiconductor detectors, etc., there are measurement accumulation and detection dead time problems, which make it difficult to achieve such a high dose rate response, that is, the instrument has an over-response problem, which will inevitably affect the accuracy of the monitoring results; active electronic dosimeters have a measurement time cycle. In order to reduce the energy consumption of the dosimeter, the interval between two measurement cycles can be up to several seconds. If the pulse radiation occurs within the interval of the instrument measurement cycle, it is very likely that an omission event will occur, which will greatly affect the accuracy of the measurement result and cause the measurement result to be seriously low; an accident in which a person accidentally enters a radiation field is also a large-dose pulse event for active personal dosimeters. In addition, a nuclear criticality accident is also a typical pulse radiation. A nuclear criticality accident refers to an unexpected critical or supercritical event caused by some unexpected reason in a system containing fissile materials. Taking a typical nuclear criticality accident as an example, a total of about 10 19 The fission occurred about 10 times in the first 0.5 seconds. 18 The fissions continue for several hours, with a fission pulse generated every 10 minutes, and each fission lasts no longer than 0.5 seconds. Therefore, the neutrons, X-rays and gamma rays produced by nuclear criticality accidents are typical pulse radiation.

[0004] Pulse radiation dose testing is extremely difficult, and existing measurement and testing technologies lag far behind the needs of pulse radiation field application technology, which directly affects the performance of related pulse radiation fields. At the same time, the lack of pulse standard radiation fields also restricts the development of pulse testing technology. Carrying out research on related calibration technologies has become an important direction for the future development of my country's ionizing radiation measurement and transmission system. Therefore, this invention is of great significance for solving the traceability problem of measuring instruments for pulse radiation dose monitoring.

[0005] IEC60846-1:2009 states that the response time of an active radiation dosimeter should not be greater than 10 seconds, so the present invention classifies ionizing radiation with a duration of less than 10 seconds as pulse radiation. Pulse X-rays in the fields of medical diagnosis, material testing, radiographic inspection, and scientific research are classified as shown in Table 1.

[0006] Table 1 Typical pulse radiation parameters

[0007]

[0008] Millisecond pulse X-rays are mainly used in fields such as radiological diagnosis, radiographic flaw detection, and personnel and object detection, and have a wide range of applications; microsecond pulse X-rays are mainly generated by electron accelerators and are mainly used in fields such as radiotherapy and irradiation processing; nanosecond pulse X-rays are mainly used in fields such as flash X-ray technology, transient imaging, and object detection. Summary of the invention

[0009] In order to solve the defects of the prior art, the purpose of the present invention is to provide a pulse X-ray reference radiation field generating device based on a pulse X-ray machine, which can realize the radiation performance parameter testing of nuclear radiation dosimeters under pulsed dynamic parts and solve the traceability problem of measuring instruments for pulse radiation dose monitoring.

[0010] In order to achieve the above object, the first technical solution adopted by the present invention is:

[0011] A pulse X-ray reference radiation field generating device based on a pulse X-ray machine, comprising a pulse X-ray machine for radiodiagnosis 1, wherein the exit port of the pulse X-ray machine for radiodiagnosis is provided with a Be window 2 and a built-in aperture 3, and an additional filtering device 4, a collimating aperture and a monitoring ionization chamber 5 are sequentially provided along the axis of the X-ray radiation field generated by the pulse X-ray machine for radiodiagnosis;

[0012] The collimating aperture and monitoring ionization chamber 5 are an integrated structure, including two collimating apertures and a monitoring ionization chamber located between the two collimating apertures;

[0013] The millisecond pulse X-ray generated by the pulse X-ray machine 1 for radiological diagnosis is emitted from the Be window 2 and the built-in aperture 3, filtered by the additional filtering device 4 to form a pulse filtered beam X-ray, and then collimated by the collimating aperture to form a millisecond pulse X-ray reference radiation field.

[0014] Furthermore, as described above, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine, the tube voltage, tube current and output pulse width of the pulse X-ray machine for radiological diagnosis are all adjustable, and the output pulse width ranges from 1ms to 10s. The instantaneous dose rate of the output pulse X-ray is changed by adjusting the tube current.

[0015] Furthermore, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine as described above, the additional filtering device 4 is used to filter out the low-energy part of the pulse X-ray to form a pulse filtered beam X-ray reference radiation.

[0016] Furthermore, as described above, the pulse X-ray reference radiation field generating device based on the pulse X-ray machine also includes a positioning device 6 for auxiliary positioning, an experimental platform 7 for carrying the instrument under test, and a pad 8 for reducing ground scattered radiation, which are arranged in sequence along the axis of the X-ray radiation field.

[0017] Furthermore, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine as described above, the positioning device 6 is located in the middle of the two collimating apertures, and the positioning device utilizes the prism refraction principle to generate laser along the axis of the radiation field, and positions the tested instrument on the axis of the radiation field according to the indicated direction of the laser.

[0018] Furthermore, as described above, the pulse X-ray reference radiation field generating device based on the pulse X-ray machine, the experimental platform 7 has X, Y, and Z three-dimensional movement and positioning functions, with a positioning accuracy of 1 mm, and the precise positioning of the instrument under test can be achieved by fine-tuning the position of the experimental platform.

[0019] Furthermore, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine as described above, the distance between the pad and the focus of the pulse X-ray machine for radiological diagnosis is greater than 1.5m, the material is aluminum, and the thickness is 5mm.

[0020] The second technical solution adopted by the present invention is:

[0021] A pulse X-ray reference radiation field generating device based on a pulse X-ray machine comprises a portable pulse X-ray generator, along the radiation field axis of the portable pulse X-ray generator are arranged an additional filtering device, a collimating aperture and a monitoring ionization chamber in sequence, the additional filtering device is located at the exit of the portable pulse X-ray generator, and the nanosecond pulse X-rays generated by the portable pulse X-ray generator are filtered by the additional filtering device and collimated by the collimating aperture to form a nanosecond pulse X-ray reference radiation field.

[0022] Furthermore, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine as described above, the filtering material used by the additional filtering device is aluminum sheet with a thickness ranging from 0.1mm to 5mm, which is used to filter out the low-energy part of the X-ray to form a pulse filtered beam X-ray reference radiation.

[0023] Furthermore, in the pulse X-ray reference radiation field generating device based on the pulse X-ray machine as described above, the collimating aperture and the monitoring ionization chamber are arranged at a distance of 15 cm from the focus of the portable pulse X-ray generator, and the divergence angle is adjustable within the range of 15°-40°.

[0024] The pulse X-ray reference radiation field generating device of the present invention has the following significant technical effects:

[0025] The present invention establishes a pulse reference radiation field based on a pulse X-ray machine, which can realize the radiation performance parameter test of the nuclear radiation dosimeter under the pulse dynamic part, and solves the traceability problem of the measuring instrument for pulse radiation dose monitoring; the pulse width of the established pulse X-ray reference radiation field is adjustable between 50ns-10s, and the instantaneous dose rate range is: 2.5mSv / h-6.7×10 5 Sv / h, covering the range of radiation dosimeters such as environmental level, protection level, diagnosis and treatment level, emergency level and nuclear critical accident level. It can be used to carry out research on the pulse radiation response characteristics of various radiation protection instruments and personal dosimeters, and can also be used to carry out testing, calibration and verification of nuclear accident critical alarm systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a device for establishing a millisecond-level pulse X-ray reference radiation field based on a pulse X-ray machine for radiodiagnosis provided in a specific embodiment of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of a device for establishing a nanosecond pulse X-ray reference radiation field based on a portable pulse X-ray generator provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention establishes a pulse reference radiation field based on a pulse X-ray machine for radiological diagnosis and a portable pulse X-ray generator. The technical solution of the present invention is further described below in conjunction with specific embodiments and drawings of the specification.

[0029] Example 1: Establishing a millisecond pulse X-ray reference radiation field based on a pulse X-ray machine for radiological diagnosis

[0030] A pulsed X-ray machine for radiological diagnosis is a typical device capable of generating millisecond-level pulsed X-rays, and has the advantages of high power and adjustable pulse width. This embodiment establishes a millisecond-level pulsed X-ray reference radiation field based on a pulsed X-ray machine for radiological diagnosis. The schematic diagram of the structure of the device is shown in FIG. Figure 1 As shown, the device comprises a pulse X-ray machine 1 for radiodiagnosis, the exit port of the pulse X-ray machine 1 for radiodiagnosis is provided with a Be window 2 and a built-in aperture 3, and an additional filtering device 4, a collimating aperture and a monitoring ionization chamber 5, a positioning device 6, an experimental platform 7 and a pad 8 are sequentially arranged along the axis of the exit port. The millisecond pulse X-rays generated by the pulse X-ray machine 1 for radiodiagnosis are emitted after passing through the Be window 2 and the built-in aperture 3, and then the low-energy rays are filtered out by the additional filtering device 4 to form a pulse filtered beam X-ray, and the pulse filtered beam X-ray is collimated by the collimating aperture 5 to form a millisecond pulse X-ray reference radiation field.

[0031] The pulse X-ray machine 1 for radiological diagnosis includes a main high-voltage generator, a rotating anode X-ray tube, an anode target material, and a cathode filament, etc. The high-voltage generator uses the "electronic lever" technology to accurately control the pulse time Tpulse, and the pulse voltage signal has no mechanical inertia delay and is sensitive to control. In this embodiment, the pulse rise and fall times are 0.6ms and 1.2ms respectively; the target material of the rotating anode X-ray tube is a tungsten-rhenium alloy. The main technical indicators of the pulse X-ray machine for radiological diagnosis are: the tube voltage range is 40 to 150kV, and 1kV is continuously adjustable; the tube current adjustment range is 1 to 800mA; the pulse duration range is: 1ms to 10s.

[0032] The additional filtering device 4 is used to properly filter the original pulse X-rays, remove the useless low-energy parts, and form a pulse filtered beam X-ray.

[0033] The collimating diaphragm and monitoring ionization chamber 5 integrate the collimating diaphragm and the monitoring ionization chamber into one, which includes multiple collimating diaphragms and a monitoring ionization chamber. In this embodiment, the number of collimating diaphragms is 2. The collimating diaphragms are used to collimate and shape the pulsed filtered beam X-rays and control the divergence angle of the filtered beam X-rays within a set range; the monitoring ionization chamber is used to monitor the stability of the pulsed X-ray field.

[0034] The positioning device 6 is located between the two collimating apertures. In this embodiment, the positioning device is a laser that uses the principle of prism refraction to generate laser light along the axis of the radiation field. The instrument being tested can be positioned on the axis of the radiation field according to the indicated direction of the laser light.

[0035] The instrument under test is placed on the experimental platform 7. In this embodiment, the size of the experimental platform is 30cm×30cm, and it has X, Y, and Z three-dimensional movement and positioning functions with a positioning accuracy of 1mm. The precise positioning of the instrument under test is achieved by fine-tuning the position of the experimental platform.

[0036] The pad 8 is located at the bottom of the pulse X-ray reference radiation, more than 1.5 m away from the focus of the pulse X-ray machine for radiological diagnosis, and is made of 5 mm thick aluminum material to effectively reduce the scattered radiation from the ground.

[0037] Example 2: Establishing a nanosecond pulse X-ray reference radiation field based on a portable pulse X-ray generator

[0038] Nanosecond pulsed X-rays are mainly used in accelerator irradiation applications, radiation processing, radiotherapy, transient imaging, plasma research and other fields, and are widely used. This embodiment establishes a nanosecond pulsed X-ray reference radiation field based on a portable pulsed X-ray generator. The schematic diagram of the structure of the device is shown in the figure. Figure 2 As shown, the device comprises a portable pulse X-ray generator 9, an additional filter device 4, a collimating aperture and a monitoring ionization chamber 5, wherein the additional filter device 4 is located at the exit of the portable pulse X-ray generator, the collimating aperture and the monitoring ionization chamber 5 are arranged on the axis of the X-ray radiation field and at a certain distance from the focus, and the entire device is fixed on a system bracket 10. The portable pulse X-ray generator 9 generates nanosecond pulse X-rays, which are filtered by the additional filter device 4 to form nanosecond filtered beam pulse X-rays, and then collimated and shaped by the collimating aperture to form a nanosecond pulse X-ray reference radiation field.

[0039] In this embodiment, the tube voltage of the portable pulse X-ray generator 1 is 270 kV, the pulse width is 25 ns, and the frequency is 15 Hz.

[0040] The additional filter device 4 is used to filter out low-energy X-rays. In this embodiment, the filter material used by the additional filter device is an aluminum sheet with a thickness ranging from 0.1 mm to 5 mm.

[0041] The collimating aperture and the monitoring ionization chamber 5 are arranged at a distance of 15 cm from the focal point of the portable pulse X-ray generator, and the divergence angle is adjustable within the range of 15°-40°.

[0042] The parameter measurement method of the pulsed X-ray reference radiation field established by the device of the present invention is as follows:

[0043] (1) Pulse time measurement

[0044] The pulse time measurement system is used to measure the pulse time of the pulse X-ray reference radiation field. The pulse time measurement system consists of a scintillator detection element, a light collector, a photoelectric conversion device (Si-PIN photodiode), a preamplifier, an oscilloscope and a DC power supply. When the scintillator probe is irradiated by pulsed X-rays, fluorescence is generated. The fluorescence is transmitted to the photoelectric conversion device (Si-PIN photodiode) through the light collector to generate an electrical signal, which is displayed by the electronic system. According to the general requirements of time measurement, the test system response must be more than 3 times faster than the pulse signal to be measured. This measurement uses CsI (Tl) crystal as a detector to obtain ms-level pulse X-ray time, and uses the S3590-19 Si-PIN photodiode of Hamamatsu Company in Japan as the photoelectric converter of the CsI crystal output. The spectral response range of this type of silicon photodiode is (340~1100)nm, which is suitable for CsI crystals. Its photosensitivity is about 0.58A / W, the maximum dark current is about 10nA, and the cut-off frequency is 40MHz.

[0045] The pulse time measurement system will display the pulse X-ray output waveform on the oscilloscope, and the pulse time is calculated by the following formula:

[0046] t pulse =t a -t b (1)

[0047] In the above formula, t pulse is the pulse time, t a is the pulse start time, t b is the pulse end time. Determine the pulse time based on the pulse output waveform displayed by the oscilloscope.

[0048] (2) Pulse X-ray dose measurement

[0049] The pulse X-ray secondary standard ionization chamber is used to measure the dose of the pulse X-ray reference radiation field. The tube voltage range of the pulse X-ray machine for radiodiagnosis is: 40-150kV; the tube current adjustment range is: 1-800mA; the pulse duration range is T pulse : 1ms~10s, the instantaneous dose rate of pulsed X-rays can be changed by adjusting the tube current, and the resulting instantaneous dose rate range is about 186mSv / h~777Sv / h.

[0050] The portable pulsed X-ray generator has a tube voltage of 270 kV, a pulse width of 25 ns, and a frequency of 15 Hz. The device cannot adjust the tube voltage, tube current, and pulse width. The instantaneous dose rate can be as high as 6.68 × 10 5 Sv / h.

[0051] The pulse X-ray reference radiation field dose based on the diagnostic X-ray machine was measured using an SSPR type pulse X-ray flat-panel ionization chamber. The measurement unit was air kerma. The ambient dose equivalent and personal dose equivalent could be obtained by multiplying the corresponding conversion coefficient. The distance from the measurement position to the focus of the X-ray machine was 1m. The pulse X-rays generated by the portable pulse X-ray generator were measured using a 34035 type flat-panel ionization chamber produced by PTW of Germany. The measurement unit was personal dose equivalent. The distance from the measurement position to the focus of the portable pulse X-ray generator was 1m.

[0052] With reference to IEC61267 and ISO4037-1 standards, the present invention establishes radiation qualities such as N-series, L-series, H series, W series) and medical diagnostic series pulsed X-ray reference radiation fields (RQR-series, RQA-series, RQB-series, RQN-series, RQT-series, RQC-series) based on pulsed X-ray machines for radiological diagnosis and portable pulsed X-ray generators. The single pulse doses and instantaneous dose rates of some radiation qualities are shown in Table 2.

[0053] Table 2 Pulse X-ray reference radiation field dose measurement results

[0054]

[0055] As can be seen from Table 2, the pulse X-ray reference radiation field dose rate range established by the present invention covers the radiation dosimeter ranges such as environmental level, protection level, diagnosis and treatment level and emergency level, and can be used to carry out research on the pulse radiation response characteristics of various radiation protection instruments and personal dosimeters, and can also be used to carry out testing, calibration and verification of nuclear accident critical alarm systems.

[0056] (3) Radiation dosimeter pulse response test

[0057] The pulse response test of four active radiation dosimeters was carried out using the pulse X-ray reference radiation field based on the pulse X-ray machine for radiological diagnosis described in the present invention. The active radiation dosimeter was placed on the axis of the pulse X-ray reference radiation field, and the distance from the focus to the reference point of the active radiation dosimeter was 1m, wherein the personal dosimeter was equipped with a phantom. The tube voltage and tube current of the pulse X-ray machine were adjusted, and the exposure time was 10ms (single pulse exposure) and 25ns (99 pulse exposures), respectively. The response of the active radiation dosimeter was calculated according to formula (2):

[0058]

[0059] Where: R pulse is the pulse response of the active radiation dosimeter; M is the reading of the active radiation dosimeter; D pulseIt is the agreed true value at the reference point in the pulsed X-ray radiation field, which is obtained from the developed secondary standard ionization chamber.

[0060] Type A and B of the four active radiation dosimeters are personal dosimeters that measure the physical quantity H. P (10), during the measurement, an ISO phantom was placed, and the C and D types were portable radiation dosimeters. The measured physical quantity was H * (10), the pulse response results of the four active detectors are shown in Tables 3 and 4. The pulse width T used in Table 3 is pulse =10ms, instantaneous dose rate The reference radiation used in Table 4 consists of 99 consecutive pulses, T pulse =25ns, instantaneous dose rate Pulse frequency f pulse =15Hz.

[0061] Table 3 Dose response of active radiation dosimeter in single pulse radiation field

[0062]

[0063] Table 4 Dose response of active radiation dosimeter in continuous pulse radiation field

[0064]

[0065] As shown in Table 3, the pulse width T pulse =10ms, pulse instantaneous dose rate Under the single pulse irradiation of , only two electronic personal dosimeters responded, 78.1% and 114% respectively, and the readings of the two active ambient dose equivalent meters were background and no alarm was displayed. As shown in Table 4, at the pulse width T pulse =25ns, pulse instantaneous dose rate Under 99 consecutive pulse irradiation, only one electronic personal dosimeter had a 4.1% response, and the other three active dosimeters had no response. The test results show that active radiation dosimeters have insufficient response in pulse radiation fields, with low readings, and are not suitable for dose measurement in short pulse and high dose rate radiation fields.

[0066] The present invention establishes a pulse X-ray reference radiation field based on a pulse X-ray machine for radiological diagnosis and a portable pulse X-ray generator, which can realize the radiation performance parameter test of a nuclear radiation dosimeter under a pulse dynamic component, and solves the traceability problem of the measuring instrument for pulse radiation dose monitoring; the pulse width of the established pulse X-ray reference radiation field is adjustable between 50ns and 10s, and the instantaneous dose rate range is: 2.5mSv / h-6.7×105 Sv / h, covering the measurement range of radiation dosimeters such as environmental level, protection level, diagnosis and treatment level, emergency level and nuclear critical accident level. It can be used to carry out research on the pulse radiation response characteristics of various radiation protection instruments and personal dosimeters, and can provide test conditions for nuclear critical accident γ radiation alarms.

[0067] The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be considered illustrative rather than restrictive in any respect. The scope of the present invention should be described by the appended claims, and any changes equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A pulse X-ray reference radiation field generating device based on a pulse X-ray machine, characterized in that: The portable pulse X-ray generator (9) comprises an additional filter device (4), a collimating aperture and a monitoring ionization chamber (5) arranged in sequence along the radiation field axis of the portable pulse X-ray generator, the additional filter device (4) being located at the exit of the portable pulse X-ray generator (9), the filter material used by the additional filter device (4) being an aluminum sheet with a thickness ranging from 0.1 mm to 5 mm, and being used to filter out the low-energy part of the X-ray to form a pulse filtered beam X-ray reference radiation; the collimating aperture and the monitoring ionization chamber (5) being arranged at a distance of 15 cm from the focal point of the portable pulse X-ray generator, and having a divergence angle adjustable within a range of 15° to 40°; the nanosecond pulse X-rays generated by the portable pulse X-ray generator (9) are filtered by the additional filter device (4) and collimated by the collimating aperture to form a nanosecond pulse X-ray reference radiation field.

2. The pulse X-ray reference radiation field generating device based on a pulse X-ray machine according to claim 1, characterized in that: The tube voltage of the portable pulse X-ray generator (9) is 270 kV.

3. The pulse X-ray reference radiation field generating device based on a pulse X-ray machine according to claim 2, characterized in that: The portable pulse X-ray generator (9) has a pulse width of 25 ns.

4. The pulse X-ray reference radiation field generating device based on a pulse X-ray machine according to claim 3, characterized in that: The frequency of the portable pulse X-ray generator (9) is 15 Hz.

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