CN212341056U - Detecting instrument - Google Patents

Abstract

The utility model discloses a detection instrument, include: a support; the pinhole collimator is arranged on the bracket; the radioactive source is arranged on the focal part of the pinhole collimator and is used for continuously emitting photon pairs from the focal part, the photon pairs comprise detection photons and position resolution photons, the emission directions of the detection photons and the position resolution photons are opposite, and the detection photons are emitted to an object to be detected to be scattered to generate scattered photons; the position sensitive detector is arranged on the end face of the large end of the pinhole collimator and used for detecting the position resolution photons with preset energy and generating position signals; and the scattering detector is arranged on the support and used for detecting the scattered photons within a preset energy range, wherein an included angle between the axis of the probe of the scattering detector and the axis of the pinhole collimator is an obtuse angle. The detector improves the number and energy of detected scattered photon events, so that the energy resolution, the signal-to-noise ratio and the total detection efficiency are greatly improved.

Description

Detecting instrument

Technical Field

The utility model relates to a nondestructive detection technology field, more specifically relates to a detection instrument.

Background

Nondestructive detection is a general term for all technical means for detecting whether a detected object has defects or non-uniformity under a detection surface by using characteristics such as sound, light, magnetism, electricity and the like, giving information such as the size, position, property, quantity and the like of the defects, and further judging the technical state (such as qualification, residual life and the like) of the detected object. Nondestructive detection has significant advantages over destructive detection and is therefore widely used.

In the prior art, a non-destructive detector mostly adopts a back scattering detection technology, and the scattering angle is greater than 90 degrees, so that scattering events are few, and the detection efficiency is low; low scattered photon energy, poor energy resolution, and poor signal-to-noise ratio.

For example, GFE corporation, under the name GSI, germany, uses sodium 22 with a diameter of 1 mm and an intensity of 1MBq to 10MBq as a radioactive source, and on the same side of the radioactive source, calculates the shape of the buried object under the ground surface or the true image of the corroded state of the inner wall of the pipeline corresponding to the backscattered gamma rays by measuring and comparing two opposite gamma ray photons generated by the decay of the positron emitted by the radioactive sodium 22 element. However, the detection device also has the problems of poor detection result reliability and low detection efficiency, and the application range is limited.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model aims at providing a detection instrument that has higher detection accuracy reliability and detection efficiency to have fabulous suitability, with the problem that exists among the solution prior art.

According to the utility model provides a detection instrument, include:

a support;

the pinhole collimator is arranged on the bracket;

the radioactive source is arranged on a focus part of the pinhole collimator and is used for continuously emitting photon pairs from the focus part, the photon pairs comprise detection photons and position resolution photons, the emission directions of the detection photons and the position resolution photons are opposite, and the detection photons are emitted to an object to be detected and scattered to generate scattered photons;

the position sensitive detector is arranged on the end face of the large end of the pinhole collimator and is used for detecting the position resolution photons with preset energy and generating position signals;

and the scattering detector is arranged on the support and used for detecting the scattered photons within a preset energy range, wherein an included angle between the axis of the probe of the scattering detector and the axis of the pinhole collimator is an obtuse angle.

Preferably, the large end of the pinhole collimator is remote from the scatter detector relative to the focal portion.

Preferably, the radiation source further comprises a shielding plate, wherein the shielding plate is arranged between the position sensitive detector and the scattering detector and is used for shielding photons emitted by the radiation source.

Preferably, the system further comprises a signal acquisition and processing system, and the signal acquisition and processing system is electrically connected with the position-sensitive detector and the scattering detector respectively.

Preferably, the probe of the position sensitive detector is made of discrete crystals, a plurality of pixel points are arranged on the probe, and photons are emitted to the pixel points, so that photon position signals are formed.

Preferably, the probe of the position sensitive detector is made of a continuous crystal, and the signal acquisition and processing system comprises two pulse amplitude converters for analog-to-digital conversion of the position signal from the position sensitive detector, thereby forming a digital pattern of the position signal.

Preferably, the radioactive source is a positron-emitting source and the photons are gamma photons;

the energy value of the position resolution photon with the preset energy is E, the E is more than 490keV and less than or equal to 511keV, and the preset energy range is 250 keV-E.

Has the advantages that:

the detector can be used for detecting objects such as underground pipelines and the like, an included angle between the axis of a probe of the scattering detector and the axis of the pinhole collimator is set to be an obtuse angle, so that the included angle between detected photons and scattered photons which are emitted to the object to be detected is positioned in a 90-degree range to the maximum extent when the object is detected, scattering events are increased, the scanning speed is higher, the position-resolved photons with preset energy are further distinguished by the position sensitive detector, the scattered photons with preset energy range are distinguished by the scattering detector, front angle zone scattering is formed during detection, the energy resolution and the signal-to-noise ratio are improved, and the detection accuracy and reliability and the detection efficiency are greatly improved; in addition, the detector has wide application range, and the position sensitive detector and the scattering detector are positioned at the same side of an object to be detected during detection, so that the detector is convenient to detect some occasions with complex structures, particularly unfavorable to or incapable of using an imaging system in a transmission measurement mode for detection.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 shows a schematic structural diagram of a detecting instrument according to an embodiment of the present invention.

Fig. 2 shows a graph of scattered photon energy as a function of scattering angle according to an embodiment of the invention.

Fig. 3 shows a flow chart of a detection method according to an embodiment of the present invention.

Fig. 4 shows a flowchart of step S02) of the detection method according to the embodiment of the present invention.

In the figure: the device comprises a radioactive source 100, a support 1, a pinhole collimator 2, a focal part 21, a cone part 22, a flange part 23, a position sensitive detector 4, a scattering detector 5, a signal acquisition and processing system 6 and a shielding plate 7.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.

As shown in fig. 1, the utility model provides a detection instrument, this detection instrument includes support 1, pinhole collimator 2, radiation source 100, position sensitive detector 4 and scatter detector 5. The pinhole collimator 2 is arranged on the bracket 1; the radiation source 100 is arranged on the focal part 21 of the pinhole collimator 2, the radiation source 100 is used for continuously emitting photon pairs from the focal part 21, the photon pairs comprise detection photons and position-resolved photons, the emission directions of the detection photons and the position-resolved photons are opposite, and the detection photons are emitted to an object to be detected to be scattered to generate scattered photons; the position sensitive detector 4 is arranged on the end face of the large end of the pinhole collimator 2 and used for detecting the position resolution photons with preset energy and generating position signals; and the scattering detector 5 is arranged on the pinhole collimator 2 and used for detecting the scattered photons within a preset energy range, wherein an included angle between the axis of the probe of the scattering detector 5 and the axis of the pinhole collimator 2 is an obtuse angle.

This is described in more detail below with reference to the accompanying drawings.

The support 1 is used for installing and bearing various components and parts, and enables the whole detector to be capable of moving integrally, adjusting and detecting during detection. In this embodiment, the support 1 is a flat plate, and the pinhole collimator 2, the position sensitive detector 4, and the scatter detector 5 are all disposed on the same plane of the flat plate. When the detector is used for detection, the bracket 1 can carry out horizontal moving type detection, for example, when a pipeline buried under the ground is detected, the bracket can carry out horizontal sliding type detection, and in this case, the lower part of the flat plate can be provided with a roller for rolling movement; of course, when the detector is used, the support 1 can also be vertically placed or placed at other angles.

The pinhole collimator 2 includes a focus portion 21, a tapered cylindrical portion 22, and a flange portion 23, wherein the focus portion 21 is connected to an end face of a small end of the tapered cylindrical portion 22, and the flange portion 23 is provided on an outer peripheral wall of an end of a large end of the tapered cylindrical portion 22. Wherein, focus portion 21 is the cylindric structure with awl section of thick bamboo portion 22 intercommunication, and the open end that focus portion 21 kept away from the one end of awl section of thick bamboo portion 22 is the horn structure, and the main aspects of horn structure sets up towards outside, and the detection photon that radiation source 100 sent of being convenient for of this kind of structure is from focus portion 21 and is jetted out. The cone part 22 is used for guiding and constraining the position-resolved photons emitted by the radiation source 100, which is beneficial to the position-resolved photons detected by the position-sensitive detector 4, and can also play a role in shielding to prevent the position-resolved photons from being emitted from multiple directions and multiple angles without constraint.

The radiation source 100 is housed in the focal portion 21 of the pinhole collimator 2. in this embodiment, the radiation source 100 is selected to be sodium-22, the half-life of the sodium-22 radiation source 100 is about 2.6 years, and the radiation source 100 needs to be replaced after the system is generally used for 8 years. The activity of the positron radiation source 100 cannot be too strong, otherwise, the dead time of the position sensitive detector 4 is too long, the counting loss is too large, meanwhile, the activity of the positron radiation source 100 cannot be too weak, otherwise, the counting rate of the scattering detector 5 is too low, the data acquisition time is too long, and the signal-to-noise ratio is poor.

The position sensitive detector 4 is arranged on the end face of the large end of the pinhole collimator 2, specifically, the position sensitive detector 4 can be fixed on the flange part 23 of the pinhole collimator 2, and the probe of the position sensitive detector 4 is coaxially arranged with the pinhole collimator 2.

In one embodiment, the probe of the position-sensitive detector 4 may be made of a discrete crystal, and the probe is provided with a plurality of pixels, and in this embodiment, the probe is divided into a plurality of pixels, and the position-resolved photons are emitted onto the pixels, so as to form a photon position signal. In an alternative embodiment, the probe of the position sensitive detector 4 is made of a continuous crystal, and the corresponding signal acquisition and processing system comprises two pulse amplitude converters for analog-to-digital conversion of the position signal from the position sensitive detector 4, so as to form a digital pattern of the position signal.

The scattering detector 5 and the position sensitive detector 4 are arranged at a preset distance interval and used for detecting scattered photons within a preset energy range, wherein an included angle between the axis of the probe of the scattering detector 5 and the axis of the pinhole collimator 2 is an obtuse angle. The large end of the pinhole collimator 2 is located away from the scatter detector 5 with respect to the focal point 21, that is, the focal point 21 of the pinhole collimator 2 is located close to the scatter detector 5 with respect to the large end of the cone 22.

Furthermore, still be equipped with shielding plate 7 on the support 1, shielding plate 7 sets up perpendicularly relative to support 1, shielding plate 7 is located position sensitive detector 4 with between the scatter detector 5 for the photon that shielding radiation source 100 jetted out prevents that the photon that radiation source 100 launched from directly shooting to scatter detector 5 on causing the influence to the detection result not waiting to detect the object scattering.

Furthermore, the detector also comprises a signal acquisition and processing system, and the signal acquisition and processing system 6 is respectively and electrically connected with the position sensitive detector 4 and the scattering detector 5.

In this embodiment, the radiation source 100 is a positron emitting source and the photons are gamma photons. Referring to fig. 2, as the scattering angle becomes smaller, the energy of the scattered photon becomes larger. The scattering angle is reduced to improve the energy resolution and the signal-to-noise ratio, considering that the fundamental noise is not changed. In this embodiment, the energy value of the position-resolved photon with the predetermined energy is E, 490keV < E ≦ 511keV, the value of E is preferably 511keV, and the predetermined energy range is 250keV to E. In this way, the scattering angle of the detected photon can be reduced as much as possible, so that the scattering of the photon is front angle region scattering, and the position-resolved photon and the scattered photon have the maximum energy, so that the energy resolution and the signal-to-noise ratio can be improved to the maximum extent.

As shown in fig. 3, the present invention also relates to a detection method, which can be implemented by using the detection instrument of the present application.

The detection method comprises the following steps:

s01), the radioactive source 100 continuously emits photon pairs, the photon pairs comprise detection photons and position-resolved photons, the emission directions of the detection photons and the position-resolved photons are opposite, the detection photons are emitted to an object to be detected and scattered to generate scattered photons, and the scattering of the photons forms front angle region scattering;

in step S01), the positron emission source continuously emits positrons, each of which annihilates with a negative electron near the focal portion 21 of the pinhole collimator 2 to generate a pair of gamma photons having an energy value E and opposite directions, and the pair of gamma photons includes a probe photon and a position-resolved photon. The position resolution photons are emitted towards the direction departing from the focus of the pinhole collimator 2, one part of the position resolution photons directly irradiate the position sensitive detector 4, the energy is not lost, the energy value can be regarded as E, the part of the position resolution photons is position resolution photons with preset energy, the part of the position resolution photons with the preset energy is effective position resolution photons, the subsequent position resolution photons can be identified and collected by the position sensitive detector 4, the other part of the position resolution photons is scattered after being irradiated onto the inner wall of the pinhole collimator 2, the energy value of the scattered position resolution photons can be lost and reduced to be below E, the part of the scattered position resolution photons can be called invalid position resolution photons, and the subsequent position resolution photons can be ignored by the position sensitive detector 4; the detection photons are emitted in the direction of the object to be detected and scattered to generate scattered photons.

S02), detecting the scattered photons, detecting the position-resolved photons, and generating an image of the object to be detected according to the detection result of the scattered photons and the detection result of the position-resolved photons.

Referring to fig. 4, in step S02), further comprising:

s021), detecting the scattered photons, and if the scattered photons within a preset energy range are detected, generating a door opening signal ts;

referring to fig. 2, in step S021), the scattering detector 5 determines an amplitude of the scattered photon pulse, screens out scattered photons within a preset amplitude range, where the photon amplitude represents energy of the photons, and only scattered photon events corresponding to energy values of 250keV to E are valid, and scattered photon events corresponding to energy values of 250keV to E are scattered corresponding to a front angle region where a scattering angle is smaller than 90 °, and then extracts a door-open signal ts.

In particular, the scatter detector 5 generates a door-open signal ts and sends this signal to the signal acquisition and processing system.

S022), detecting the position-resolved photons, generating an event signal te if the position-resolved photons with preset energy are detected within a time window delta t after a door opening signal ts is generated, judging that the door opening signal ts is in accordance with the event signal te, and obtaining a corresponding group of position signals according to the detection result of the detected position-resolved photons;

specifically, the position sensitive detector 4 detects the position-resolved photon, discriminates the amplitude of the position-resolved photon, screens out the effective position-resolved photon, extracts the arrival time signal only when the photon event corresponding to the energy value E is detected, and generates the event signal te after a certain delay. After the signal acquisition and processing system receives a door opening signal ts, in a time window delta t, if the signal acquisition and processing system receives a time signal te from the position sensitive detector 4, the door opening signal ts is judged to be in accordance with the event signal te, an enabling signal En is sent to the position sensitive detector 4, and after the position sensitive detector 4 receives the enabling signal En, a group of position signals is sent to the signal acquisition and processing system according to the detection result of distinguishing photons from the effective position, wherein the corresponding position signals can be represented by position coordinates X and Y.

It should be noted that, in this step, when the probe of the position sensitive detector 4 is made of a discrete crystal, the probe is divided into a plurality of pixel points, and the position-resolved photons are emitted onto the pixel points, so as to form a photon position signal, which is a digital signal and can be directly transmitted to a signal acquisition and processing system for subsequent data processing. When the probe of the position sensitive detector 4 is made of continuous crystals, the position signal acquired by the position sensitive detector 4 under the condition is an analog signal, and the corresponding signal acquisition and processing system comprises two pulse amplitude converters which perform analog-to-digital conversion on the position signal from the position sensitive detector 4, so that a digital position signal is formed and then subsequent data processing is performed.

S023) repeating the steps to obtain a plurality of groups of position signals, and generating the image of the object to be detected according to the plurality of groups of position signals.

And repeating the step S021) to the step S022), obtaining a plurality of groups of position signals by the signal acquisition and processing system, generating a distribution diagram reflecting the scattering intensity of the object according to the obtained plurality of groups of position signals, and further obtaining an image of the object to be detected.

When an object to be detected is detected, the detector can be moved to change the relative position between the detector and the object to be detected, and the detector can be detected and imaged at different positions.

The imaging display of the object to be detected can be directly imaged on the signal acquisition and processing system, or the imaging unit can be displayed on the position-sensitive detector for imaging, and in addition, a separate imaging device can be arranged and electrically connected with the signal acquisition and processing system for displaying the detected object image.

In addition, in this embodiment, the radiation source 100 is a positron emission source 100. Referring to fig. 2, as the scattering angle becomes smaller, the energy of the scattered photon becomes larger. The scattering angle is reduced to improve the energy resolution and the signal-to-noise ratio, considering that the fundamental noise is not changed. In this embodiment, the energy value of the position-resolved photon with the predetermined energy is E, 490keV < E ≦ 511keV, the value of E is preferably 511keV, and the predetermined energy range is 250keV to E. In this way, the scattering angle of the detected photon can be reduced as much as possible, so that the scattering of the photon is front angle region scattering, and the position-resolved photon and the scattered photon have the maximum energy, so that the energy resolution and the signal-to-noise ratio can be improved to the maximum extent.

The detector can be used for detecting objects such as underground pipelines and the like, an included angle between the axis of a probe of the scattering detector 5 and the axis of the pinhole collimator 2 is set to be an obtuse angle, so that the included angle between a detected photon and a scattered photon which are emitted to the object to be detected when the object is detected is located in a range of 90 degrees to the maximum extent, scattering events are increased, the scanning speed is higher, the position sensitive detector 4 is used for distinguishing a position resolution photon with preset energy, the scattering detector 5 is used for distinguishing the scattered photon with the preset energy range, front angle region scattering is formed when the object is detected, the energy resolution and the signal to noise ratio are improved, and the detection accuracy and reliability and the detection efficiency are greatly improved; in addition, the detector has wide application range, and the position sensitive detector 4 and the scattering detector 5 are positioned at the same side of an object to be detected during detection, so that the detection is convenient for detecting some occasions with complex structures, particularly unfavorable to or incapable of using an imaging system in a transmission measurement mode for detection.

The detection method in the application improves the quantity and energy of detected scattered photon events, and enables energy resolution, signal-to-noise ratio and total detection efficiency to be greatly improved. In addition, the detection method has wide application range, is convenient for detecting occasions with complex structures, and is particularly unfavorable for or can not be carried out by using an imaging system in a transmission measurement mode.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious changes and modifications may be made without departing from the scope of the present invention.

Claims (7)

1. A probe, comprising:

a support;

the pinhole collimator is arranged on the bracket;

the radioactive source is arranged on a focus part of the pinhole collimator and is used for continuously emitting photon pairs from the focus part, the photon pairs comprise detection photons and position resolution photons, the emission directions of the detection photons and the position resolution photons are opposite, and the detection photons are emitted to an object to be detected and scattered to generate scattered photons;

the position sensitive detector is arranged on the end face of the large end of the pinhole collimator and is used for detecting the position resolution photons with preset energy and generating position signals;

and the scattering detector is arranged on the support and used for detecting the scattered photons within a preset energy range, wherein an included angle between the axis of the probe of the scattering detector and the axis of the pinhole collimator is an obtuse angle.

2. The detector of claim 1, wherein a larger end of the pinhole collimator is distal from the scatter detector relative to the focal portion.

3. The detector of claim 1, further comprising a shield disposed between the position sensitive detector and the scatter detector for shielding photons emitted from the radiation source.

4. The probe according to claim 1, further comprising a signal acquisition and processing system electrically connected to the position sensitive detector and the scatter detector, respectively.

5. The detector of claim 4, wherein the probe of the position sensitive detector is made of a discrete crystal, and the probe is provided with a plurality of pixels to which photons are emitted, thereby forming a photon position signal.

6. The probe of claim 4, wherein the probe of the position sensitive detector is made of a continuous crystal and the signal acquisition and processing system includes two pulse amplitude converters for analog-to-digital conversion of the position signal from the position sensitive detector to form a digital pattern of the position signal.

7. The detector according to any one of claims 1 to 6, wherein the radioactive source is a positron emitting source;

the energy value of the position resolution photon with the preset energy is E, the E is more than 490keV and less than or equal to 511keV, and the preset energy range is 250 keV-E.

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