阅读说明：本技术 一种用于棒状放射源均匀辐照场构建的准直器及装置 (Collimator and device for constructing uniform irradiation field of rod-shaped radioactive source ) 是由 熊立东 陆艳婷 张猛超 刘超纲 翁秀峰 王炳奎 杨文新 崔亚军 陈金跃 于 2021-08-25 设计创作，主要内容包括：本发明公开一种用于棒状放射源均匀辐照场构建的准直器及装置,涉及核辐射计量校准技术领域,准直器中设置有用于透过射线的通道,沿射线的传播方向,所述通道包括直径逐渐均匀扩大的第一锥形段及第一圆柱段,所述第一锥形段与所述第一圆柱段同轴首尾连通,且所述第一圆柱段的直径不小于所述第一锥形段的最大直径,且所述通道的中轴线与棒状放射源的中轴线垂直正对；本发明中的准直器包括首尾连通的第一锥形段与第一圆柱段,第一锥形段可以将纵向视场进行有效限束,第一圆柱段可准直并减小γ射线(γ光子)与准直器的构造材料发生的康普顿散射的低能成分,使射线能谱更单能,使剂量均匀性更好。(The invention discloses a collimator and a device for constructing a uniform irradiation field of a rod-shaped radioactive source, and relates to the technical field of nuclear radiation metering calibration.A passage for transmitting rays is arranged in the collimator, and the passage comprises a first conical section and a first cylindrical section, the diameters of which are gradually and uniformly expanded, the first conical section and the first cylindrical section are coaxially communicated end to end, the diameter of the first cylindrical section is not less than the maximum diameter of the first conical section, and the central axis of the passage is vertically opposite to the central axis of the rod-shaped radioactive source; the collimator comprises a first conical section and a first cylindrical section which are communicated end to end, the first conical section can effectively limit beams of a longitudinal field of view, and the first cylindrical section can collimate and reduce low-energy components of Compton scattering generated by gamma rays (gamma photons) and structural materials of the collimator, so that a ray energy spectrum is more unipotent, and the dose uniformity is better.)

1. A collimator for constructing a uniform irradiation field of a rod-shaped radioactive source is characterized in that a passage for penetrating rays is arranged in the collimator, and the passage comprises a first conical section and a first cylindrical section, wherein the diameter of the first conical section and the diameter of the first cylindrical section are gradually and uniformly enlarged along the propagation direction of the rays; the central axis of the channel is vertically opposite to the central axis of the rod-shaped radioactive source.

2. The collimator of claim 1, wherein the first cylindrical section is further terminated by a second cylindrical section that is coaxial or a second conical section that increases in diameter uniformly along the direction of propagation of the radiation.

3. A collimator according to claim 2, wherein the rod-shaped radiation source for the collimator is a rod-shaped radiation sourceThe diameter of two end parts of the first conical hole is 24mm and 40mm respectively, and the length of the first conical hole is 50 mm; the diameter of the first cylindrical section is 40mm, and the length is 100 mm.

4. The collimator of claim 3, wherein the second conical section is connected to the end of the first cylindrical section, and the second conical section has a diameter of 38mm and a diameter of 40mm and a length of 50 mm.

5. A collimator according to claim 2, wherein the rod-shaped radiation source for the collimator is a rod-shaped radiation sourceThe diameter of two end parts of the first conical hole is 40mm and 70mm respectively, and the length of the first conical hole is 200 mm; the diameter of the first cylindrical section is 80mm, and the length is 50 mm.

6. The collimator of claim 5, wherein the second cylindrical section is further connected to the end of the first cylindrical section, the second cylindrical section having a diameter of 40mm and a length of 50 mm.

7. The collimator of claim 1, wherein the collimator is made of stainless steel or lead.

8. A device for constructing a uniform irradiation field of a rod-shaped radioactive source is characterized by comprising a shielding cover, wherein the rod-shaped radioactive source is arranged in the shielding cover, a hole is formed in the wall of the shielding cover, the collimator according to any one of claims 1-7 is arranged in the hole, and the central axis of the channel on the collimator is vertically opposite to the central axis of the rod-shaped radioactive source.

9. The apparatus as claimed in claim 8, wherein the distance between the central axis of the rod-shaped radioactive source and the inner end of the collimator is 55 mm.

10. The apparatus of claim 8, wherein the shielding case is made of stacked lead blocks, and the lead blocks are overlapped at staggered joints.

Technical Field

The invention relates to the technical field of nuclear radiation metering calibration, in particular to a collimator and a device for constructing a uniform irradiation field of a rod-shaped radioactive source.

Background

In the prior art, common radioactive sources used for a uniform irradiation field are cesium-137 sources and cobalt-60 sources, and are point sources with low activity. The half-life period of the cobalt-60 radioactive source is 5.27 years, the activity change of an irradiation field is large, and the cobalt-60 radioactive source is less adopted; the cesium-137 radioactive source has a half-life of 30.17 years, has small activity variation of the radiation source, and is commonly used in a uniform radiation field. The construction of the radiation uniform field of the existing cesium-137 radioactive source is based on a punctiform radioactive source, and the activity of the radioactive source is low and is only hundreds of curies or lower. High activity, generally rod-like sources (e.g., cobalt-60 radioactive source having a general specification ofThe rod-shaped source and the cesium-137 radioactive source have the general specification of A rod-like source).

Because the requirement of verification and calibration on a radiation field of an isotope radioactive source is higher, a rod-shaped source is usually selected as the radioactive source, but most devices in the prior art are devices constructed by a uniform irradiation field of a point-shaped source, for example, in the invention patent with the application number of '201410679413.7' named as 'a gamma-ray collimator for referencing a gamma radiation field', the point source can be clearly known according to the description attached to fig. 1 and 2, the device capable of having a special light path channel can construct the uniform irradiation field of the point-shaped radioactive source, but the device cannot be suitable for the rod-shaped radioactive source; also as an invention patent with application number "201911305403.6" entitled "collimator for quasi-monoenergetic neutron reference radiation field", it is directed to point sources as well. Therefore, in the prior art, the application of the rod-shaped radioactive source is relatively wide, the corresponding irradiation device is relatively common, and special equipment constructed for the rod-shaped source uniform irradiation field is rarely reported.

Therefore, in order to provide a standard gamma-ray uniform radiation field with single energy and the same dose rate (the unevenness is less than 2%) in a certain space of experiments such as sensitivity calibration of a low-sensitivity radiation detection system, detection of nuclear instruments and meters and the like, so that a rod-shaped radioactive source can serve scientific experiments better, a special device constructed by the uniform radiation field is urgently needed.

Disclosure of Invention

The invention aims to provide a collimator and a device for constructing a uniform irradiation field of a rod-shaped radioactive source, which are used for solving the problems in the prior art, so that the emergent port of the rod-shaped radioactive source has higher radiation dose rate, higher signal-to-noise ratio, more simple rays and better dose uniformity.

In order to achieve the purpose, the invention provides the following scheme: the invention provides a collimator for constructing a uniform irradiation field of a rod-shaped radioactive source, wherein a channel for transmitting rays is arranged in the collimator, and the channel comprises a first conical section and a first cylindrical section, the diameters of which are gradually and uniformly expanded, along the propagation direction of the rays, the first conical section is coaxially communicated with the first cylindrical section end to end, and the diameter of the first cylindrical section is not less than the maximum diameter of the first conical section; the central axis of the channel is vertically opposite to the central axis of the rod-shaped radioactive source.

Preferably, the end of the first cylindrical section is further connected with a coaxial second cylindrical section or a second conical section with the diameter uniformly increasing along the ray propagation direction.

Preferably, the rod-shaped radioactive source suitable for the collimator isThe diameters of two end parts of the first conical hole are respectively 24mm and 40mm, and the length of the first conical hole is 50 mm; the diameter of the first cylindrical section is 40mm, and the length is 100 mm.

Preferably, the tail end of the first cylindrical section is further connected with the second conical section, the diameters of two ends of the second conical section are respectively 38mm and 40mm, and the length of the second conical section is 50 mm.

Preferably, the rod-shaped radioactive source suitable for the collimator isThe diameters of two end parts of the first conical hole are 40mm and 70mm respectively, and the length of the first conical hole is 200 mm; the diameter of the first cylindrical section is 80mm, and the length is 50 mm.

Preferably, the second cylindrical section is further connected to the tail end of the first cylindrical section, and the diameter and the length of the second cylindrical section are 40mm and 50mm respectively.

Preferably, the collimator is made of stainless steel or lead.

The invention also provides a device for constructing the uniform irradiation field of the rod-shaped radioactive source, which comprises a shielding cover, wherein the rod-shaped radioactive source is arranged in the shielding cover, a hole is formed in the wall of the shielding cover, the collimator is arranged in the hole, and the central axis of the channel on the collimator is vertically opposite to the central axis of the rod-shaped radioactive source.

Preferably, the distance between the central axis of the rod-shaped radioactive source and the inner end of the collimator is 55 mm.

Preferably, the shielding case is formed by stacking lead blocks, and the lead blocks are in staggered joint and lap joint.

Compared with the prior art, the invention has the following technical effects:

1. the collimator comprises a first conical section and a first cylindrical section which are communicated end to end, the first conical section can effectively limit beams of a longitudinal field of view, the first cylindrical section can collimate and reduce gamma rays (gamma photons) and low-energy components of Compton scattering generated by construction materials of the collimator, so that a ray energy spectrum is more unipotent, the dose uniformity is better, and the collimator can be matched with a rod-shaped radioactive source to construct a high-activity uniform irradiation field;

2. the two types of collimators in the invention can be well matchedThe ten thousand curie-level rod-shaped cesium-137 radioactive source can completely meet the requirements that the radiation rate of an emergent port is more than 50R/min, the uniformity is better than 2 percent (namely less than 2 percent), and the construction mode of the shielding cover enables the signal-to-noise ratio (SNR) of the whole device to be not less than 1000, so that the rod-shaped radioactive source can better serve scientific experiments.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of a first type of collimator;

FIG. 2 is a schematic diagram of a second type of collimator;

FIG. 3 is a schematic view of a shield formed by stacking lead blocks;

wherein, 1, a collimator; 2. a first conical section; 3. a first cylindrical section; 4. a second conical section; 5. a second cylindrical section; 6. a shield case; 7. a rod-like radioactive source; 8. and (6) opening holes.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a collimator and a device for constructing a uniform irradiation field of a rod-shaped radioactive source, which are used for solving the problems in the prior art, so that the emergent port of the rod-shaped radioactive source has higher radiation dose rate, higher signal-to-noise ratio, more simple rays and better dose uniformity.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Example 1:

as shown in fig. 1 to fig. 2, in the present embodiment, a collimator for constructing a uniform irradiation field of a rod-like radioactive source is provided, a passage for transmitting a ray is provided in the collimator 1, along a propagation direction of the ray, the passage includes a first conical section 2 and a first cylindrical section 3, the diameters of the first conical section 2 and the first cylindrical section 3 are gradually and uniformly enlarged, the first conical section 2 and the first cylindrical section 3 are coaxially communicated end to end, and the diameter of the first cylindrical section 3 is not less than the maximum diameter of the first conical section 2; the central axis of the channel is vertically opposite to the central axis of the rod-shaped radioactive source 7.

When in use, the rod-shaped radioactive source 7 is placed in a shielding case 6, a hole is formed in the shielding case 6, the collimator 1 in the embodiment is arranged in the hole, and meanwhile, the shielding effect between the hole and the collimator 1 is ensured, and the ray leakage is reduced; in the process that the rod-shaped radioactive source 7 radiates outwards, rays are emitted through the first conical section 2 and the first cylindrical section 3 in sequence; the size of the area range of the source aimed by the collimator 1 is close to that of the transverse and longitudinal aimed source areas, which is a necessary condition of the uniformity of the dose field on the end surface of the collimator 1, the first conical section 2 in the collimator 1 can effectively limit the beam of the longitudinal field of view, and the first cylindrical section 3 can reduce the low-energy components of the Compton effect generated by gamma rays (gamma photons) and the construction materials of the collimator 1, so that the ray energy spectrum is more unipotent, and the dose uniformity is better; therefore, the collimator 1 in the embodiment can be matched with the rod-shaped radioactive source 7 to construct a high-activity uniform irradiation field.

Furthermore, in the embodiment, the end of the first cylindrical section 3 is connected with a coaxial second cylindrical section 5 or a second conical section 4 with a diameter uniformly increasing along the ray propagation direction, so that the uniformity of the dose is better.

In particular, this trueThe collimator 1 in the embodiment is adapted to rod-like radiation sources 7A ten thousand curie grade rod cesium-137 radiation source; the collimator 1 can be of two different types, as a first type of the collimator 1, the two end parts of the first conical section 2 are respectively 24mm and 40mm in diameter and 50mm in length; the diameter of the first cylindrical section 3 is 40mm, the length is 100mm, and the distance between the end part of the collimator 1 and the central axis of the rod-shaped radioactive source 7 is 55 mm; the collimator 1 with the structure is obtained by continuous improvement, the radiation rate of an exit port is more than 50R/min, the uniformity is better than 2 percent (namely less than 2 percent), and the signal-to-noise ratio SNR of the whole device is not less than 1000 due to the use of the shielding cover 6. This is difficult to achieve with collimators 1 of other sizes and shapes.

The following table shows the comparison of the effects of other dimensions and different channel configurations.

In the table, the proximal end of the cone-shaped section refers to the end close to the rod-shaped radioactive source 7, and the distal end is the end far away from the rod-shaped radioactive source 7.

In order to further improve the ray uniformity, in this embodiment, the end of the first cylindrical section 3 is further connected with a second conical section 4, and the diameter of both ends of the second conical section 4 is 38mm, 40mm, respectively, and the length is 50 mm.

As a second type of the collimator 1, the two end portions of the first tapered hole in the collimator 1 have diameters of 40mm and 70mm, respectively, and a length of 200 mm; the first cylindrical section 3 has a diameter of 80mm and a length of 50 mm. The tail end of the first cylindrical section 3 is also connected with a second cylindrical section 5, the diameter of the second cylindrical section 5 is 40mm, and the length of the second cylindrical section is 50 mm. This type of collimator 1 is larger in size and more complex in structure than the previous type of collimator 1, but the dose rate and uniformity at the outlet are better, so that a person skilled in the art can select it according to practical experimental conditions.

Further, in this embodiment, the collimator 1 is made of stainless steel or lead.

Example 2:

as shown in fig. 3, the embodiment further provides a device for constructing a uniform irradiation field of a rod-shaped radioactive source, which includes a shielding case 6, the shielding case 6 is internally provided with the rod-shaped radioactive source 7, a hole is formed in the wall of the shielding case 6, the collimator 1 is arranged in the hole, the size of the hole is matched with the size of the collimator 1, and the central axis of the passage on the collimator 1 is vertically opposite to the central axis of the rod-shaped radioactive source 7. Wherein the rod-shaped radioactive source 7 is fixed in the shielding 6 and a handle for carrying the whole device can be arranged on the top of the shielding 6, which is not shown in the figure.

The distance between the central axis of the rod-shaped radioactive source 7 and the inner end of the collimator 1 is 55mm so as to match the structural size of the collimator 1.

The shielding case 6 in this embodiment may be integrally formed by using lead, or may be formed by stacking lead blocks, where the commonly used lead blocks have various specifications such as 200mm × 100mm × 50mm, 200mm × 100mm × 25mm, and when stacking, the lead blocks need to be overlapped at staggered joints, and multiple layers are arranged inside and outside to avoid ray leakage; the opening 8 is to be preset on the lead block corresponding to the position of the collimator 1, and the specific stacking method is well known to those skilled in the art and can be reasonably stacked according to their own requirements, which is not described in detail in this embodiment.

The integrated device in the embodiment can better provide a standard gamma-ray uniform radiation field with single energy and the same dose rate (the unevenness is less than 2%) in a certain space of experiments such as sensitivity calibration of a low-sensitivity radiation detection system, nuclear instrument and meter detection and the like, so that the rod-shaped radioactive source 7 can better serve scientific experiments.

The adaptation according to the actual requirements is within the protection scope of the present embodiment.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.