JP7054322B2 - Equipment for measuring the amount of activation and method for measuring the amount of activation - Google Patents

Description

The present invention relates to a neutron measuring member and a method for measuring an amount of activation.

In neutron capture therapy, it is necessary to appropriately control the dose of neutron rays that irradiate the irradiation target position of the irradiated object. Therefore, for example, as described in Patent Document 1, a method of attaching a gold wire for neutron measurement to a target site and estimating the distribution of neutrons from the amount of activation of the gold wire is used.

Japanese Unexamined Patent Publication No. 2004-233168

However, in order to evaluate the distribution of neutrons, it is necessary to arrange a plurality of gold wires at different positions and then measure the amount of activation of each of the plurality of gold wires. In an environment where neutron rays are irradiated, if an attempt is made to accurately arrange each of a plurality of gold wires at a target position, the amount of work increases.

The present invention has been made in view of the above, and an object of the present invention is to provide a neutron measuring member capable of accurately measuring a neutron distribution and a method for measuring an amount of activation.

In order to achieve the above object, the neutron measuring member according to one embodiment of the present invention includes a plurality of activating members made of a metal that is activated by irradiation with neutron rays, and the plurality of activating members having a predetermined interval. It has a fixed portion, which is fixed by.

According to the above-mentioned neutron measuring member, since a plurality of activating members are fixed to the fixing member at predetermined intervals, radiation is emitted as compared with the case where the plurality of activating members are individually arranged at desired positions. The chemical members can be arranged appropriately, and the distribution of neutrons can be measured accurately.

Here, the fixing portion may be in the form of a sheet-like member having plasticity.

As described above, when the fixed portion is a sheet-like member having plasticity, the fixed portion can be deformed according to the shape of the place where the neutron is to be measured, and so on. Sound that accurately measures the distribution of neutrons is possible.

Further, the activation amount measuring method according to one embodiment of the present invention is a method for measuring the activation amount of a neutron measuring member, and includes a plurality of activation members made of a metal activated by irradiation with a neutron beam. , A step of preparing a neutron measuring member after neutron irradiation, which has a fixing portion in which the plurality of activating members are fixed at predetermined intervals, and a plurality of at the same intervals as the intervals at which the activating members are fixed. The step of bringing the plurality of activation members of the neutron measuring member into contact with each of the plurality of holes of the gamma ray collimeter in which the holes are formed, and the step of bringing the plurality of activation members into contact with each of the plurality of activation members. It has a step of individually detecting radiation waveguideed in each of a plurality of holes by a radiation detector.

According to the above-mentioned activation amount measuring method, using a gamma-ray collimator in which a plurality of holes are formed at the same interval as the interval in which the plurality of activated members are fixed in the neutron measuring member, from each of the plurality of activated members. It is possible to detect the emitted radiation individually. Therefore, the amount of activation of a plurality of activation members of the neutron measurement member can be individually and accurately measured.

Further, the activation amount measuring method according to one embodiment of the present invention is a method for measuring the activation amount of a neutron measuring member, and includes a plurality of activating members made of a metal activated by irradiation with radiant rays. A step of preparing a radiant measuring member after radiant irradiation, which comprises a fixing portion in which the plurality of activating members are fixed at predetermined intervals, and an activating member of one of the plurality of activating members. The one activation member in a state where one of the plurality of activation members of the neutron measuring member is in contact with the hole of the shielding member in which the hole corresponding only to the hole is formed. The step of detecting the radiation emitted from each of the shielding members and radiating through the holes of the shielding member by the radiation detector, and the activating member in contact with the holes of the shielding member are different from the one activating member. It has a step of detecting the radiation emitted from the other activating member and waveguide through the hole of the shielding member by the radiation detector.

According to the above-mentioned activation amount measuring method, one of a plurality of activation members is activated by using a shielding member in which a hole corresponding to only one of the activation members is formed. After detecting the radiation emitted from the shielding member, the activating member in contact with the hole of the shielding member is changed from one member to another member to detect the radiation. With such a configuration, it is possible to individually detect the radiation emitted from each of the plurality of activation members. Therefore, the amount of activation of a plurality of activation members of the neutron measurement member can be individually and accurately measured.

INDUSTRIAL APPLICABILITY According to the present invention, a neutron measuring member capable of accurately measuring a neutron distribution and a method for measuring an amount of activation are provided.

It is a figure explaining the neutron measuring member and the activation amount measuring apparatus. It is a figure explaining the activation amount measuring method. It is a figure explaining one example of the method of measuring the amount of activation. It is a figure explaining another embodiment of the method of measuring the amount of activation.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a diagram showing a neutron measuring member according to an embodiment of the present invention and an activation amount measuring device used for measuring the activation amount of the neutron measuring member. FIG. 1A is a schematic configuration diagram of the neutron measuring member 1, and FIG. 1B is a schematic configuration diagram of the activation amount measuring device 2.

The neutron measuring member 1 has a plurality of activation members 11 and a fixing portion 12 for fixing the plurality of activation members 11. The neutron measuring member 1 is used for measuring the distribution of neutron intensity in an environment where a neutron beam is irradiated, such as a neutron capture therapy system. When the neutron measuring member 1 is used in a neutron capture therapy system, it is used, for example, to measure the intensity distribution along the beam axis direction of a device that irradiates a neutron beam N.

The activation member 11 of the neutron measurement member 1 is made of a metal material that activates when irradiated with neutrons. Examples of the metal material that is activated when irradiated with neutron rays include gold, iodine, and manganese. Since the amount of activation of these metals changes according to the intensity of the irradiated neutrons, the intensity of neutrons can be estimated by measuring this amount of activation.

The shape of the plurality of activation members 11 can be, for example, linear or foil-like. However, the activation member 11 has a size and a thickness that does not disturb the neutron field, respectively. Specifically, the size of the activating member 11 can be, for example, an area of about 2 mm × 2 mm and a thickness of about 0.5 mm when the gold leaf is used as the activating member 11. If the activation member 11 is too large, the measurement accuracy will decrease. On the other hand, if the activation member 11 is too small, the detection efficiency is lowered. Therefore, the size can be appropriately selected in consideration of the type of metal and the like.

The activation members 11 are arranged on the fixing portion 12 at predetermined intervals. The spacing of the activating members 11 is determined based on the measurement spacing of the neutron intensity distribution.

The fixing portion 12 to which the plurality of activating members 11 are fixed is a sheet-shaped member made of a material that does not disturb the neutron field. As the material of the fixing portion 12, for example, acrylic resin or the like can be used, but the material is not particularly limited. However, if the fixing portion 12 has plasticity, the handleability is improved. Further, if the fixed portion 12 has plasticity, for example, even if the target position for measuring the intensity distribution of neutrons is arranged in a curved shape, it can be deformed according to the shape. , It becomes possible to correspond to various measurement conditions.

The size of the fixing portion 12 is set according to the number and arrangement (interval) of the activating members 11 attached to one neutron measuring member 1. The number of radiating members 11 attached to the fixing portion 12 is not particularly limited. In addition, the arrangement can be changed as appropriate. FIG. 1A shows an example in which the activating members 11 are arranged in a row with respect to the fixing portion 12, but a plurality of activating members 11 are two-dimensionally arranged with respect to the sheet-shaped fixing portion 12. It may have been done.

The thickness of the fixed portion 12 is not particularly limited, but it is preferable to make the fixed portion 12 thinner so as not to disturb the neutron field.

The activation member 11 may be fixed to the surface of the fixing portion 12, or may be fixed by sandwiching the activation member 11 with a plurality of sheet-shaped members, for example. The fixing portion 12 is not particularly limited as long as the activation member 11 can be fixed so that the plurality of activation members 11 are held at predetermined intervals.

After calculating the amount of activation, when calculating the neutron intensity from the calculation result, the type of material (type of metal) of the activation member 11 included in the neutron measurement member 1 and the relative position (between the activation members 11). Distance) and the mass of each of the activation members 11. However, the relative positions and masses of the plurality of activation members 11 may differ depending on the neutron measurement member 1. Therefore, the neutron measuring member 1 records the above information in advance for each neutron measuring member 1 before use. Then, when calculating the neutron intensity based on the amount of activation, the amount of neutron is calculated in each activation member 11 by using the information recorded in advance for each neutron measuring member 1. The above information (material type, relative position, and mass of the activation member 11) for each neutron measurement member 1 is associated with information that individually identifies the neutron measurement member 1 (for example, a serial number, etc.) in advance. It can be managed as a database.

Next, the activation amount measuring device 2 for measuring the activation amount related to the activation member 11 of the neutron measurement member 1 will be described. As shown in FIG. 1 (b), the activation amount measuring device 2 includes a gamma ray absolute value measuring device 21, a gamma ray individual measuring device 22 (radiation detector), and a measured value calibration unit 23. The functional unit included in the activation amount measuring device is configured by combining a plurality of devices (measuring instruments).

The gamma ray absolute value measuring device 21 has a function of measuring the absolute amount of gamma rays generated by the activation of the plurality of activating members 11 of the neutron measuring member 1. As the gamma ray absolute value measuring device 21, a known gamma ray detector can be used.

The individual gamma ray measuring device 22 has a function of measuring the dose of gamma rays generated by the activation of the plurality of activation members 11 of the neutron measuring member 1 for each activation member 11. The method of measuring each activation member 11 individually will be described in detail later, but the gamma ray from the activation member 11 to be measured and the gamma ray from the adjacent activation member 11 are separately measured.

The measured value calibration unit 23 calibrates the gamma ray dose for each activation member 11 measured by the individual gamma ray measuring instrument 22 with the gamma ray dose measured by the gamma ray absolute value measuring instrument 21, and for each activation member 11. It has a function of calculating the dose of gamma rays, that is, the amount of activation for each activation member 11. The dose of gamma rays for each activation member 11 by the individual gamma ray measuring device 22 may have a small numerical value because it is measured separately from the gamma rays from the adjacent activation member 11 as described above. Therefore, the measured value calibration unit 23 can more accurately calculate the gamma ray dose for each activation member 11 by calibrating using the gamma ray dose measured by the gamma ray absolute value measuring device 21. The measured value calibration unit 23 can be configured as an electronic control unit composed of a CPU, ROM, RAM, and the like.

It is not necessary to measure the absolute value by the gamma ray absolute value measuring device 21 and calibrate by the measured value calibration unit 23. Even in that case, the dose of gamma rays can be measured for each activation member 11 and the amount of activation can be calculated.

Next, a method for measuring the amount of activation will be described with reference to FIG. First, the neutron measuring member 1 is placed in the area to be measured (S01). At this time, by appropriately arranging the neutron measuring member 1 at a desired position, each of the plurality of activating members 11 is arranged at a desired position. Next, the neutron beam is irradiated to activate each activation member 11 of the neutron measurement member 1 (S02). As a result, the neutron measuring member 1 in which each activating member 11 is activated after the neutron beam irradiation is prepared.

After that, for the neutron measuring member 1, the gamma ray absolute value measuring device 21 measures the absolute value of the gamma rays generated by the plurality of activating members 11 (S03), and the gamma rays of the gamma rays of each of the plurality of activating members 11 are individually measured. The measurement (S04) by the measuring instrument 22 is performed. These measurements (S02, S03) may be performed simultaneously or individually. Further, the measurement order is not particularly limited.

An embodiment of the measurement by the gamma ray absolute value measuring device 21 and the measurement by the gamma ray individual measuring device 22 will be described with reference to FIG.

In the embodiment shown in FIG. 3, the measurement by the gamma ray absolute value measuring device 21 and the measurement by the gamma ray individual measuring device 22 are simultaneously performed on both sides of the neutron measuring member 1. First, in the lower part of the drawing of the neutron measuring member 1, the gamma ray from each activation member 11 of the neutron measuring member 1 is measured by the gamma ray detector as the gamma ray absolute value measuring device 21. Since the gamma rays generated in the activation member 11 are emitted isotropically, the gamma ray absolute value measuring device 21 provided below the neutron measuring member 1 is emitted from the plurality of activation members 11 of the neutron measuring member 1. Half of the gamma rays can be detected. Therefore, by doubling the dose of gamma rays detected by the gamma ray absolute value measuring device 21, the absolute value of gamma rays emitted from the plurality of activating members 11 of the neutron measuring member 1 can be calculated.

On the other hand, above the drawing of the neutron measuring member 1, a gamma ray individual measuring device 22 in which a position sensitive gamma ray detector 31 (radiation detector) and a gamma ray collimeter 32 are combined is provided. The gamma ray collimator 32 has a plurality of holes 32a (openings) provided at corresponding positions of the plurality of activation members 11 of the neutron measurement member 1, and detects gamma rays from each activation member 11 as a position-sensitive gamma ray. It is waveguide to the device 31. The gamma ray collimator 32 shields radiation (gamma ray) except for the hole 32a. Further, at the time of measurement, each of the plurality of activation members 11 of the neutron measurement member 1 is in contact with each of the plurality of holes 32a of the gamma ray collimator 32. Therefore, gamma rays from the adjacent activation member 11 are prevented from entering another hole 32a.

When gamma ray measurement is performed with the gamma ray collimator 32 and the position sensitive gamma ray detector 31 arranged as described above, the gamma ray emitted from each activation member 11 passes through different holes 32a and is position sensitive. By reaching the gamma ray detector 31, the position-sensitive gamma ray detector 31 measures the gamma ray dose from each of the plurality of activation members 11 by individually measuring the gamma rays incident from the different holes 32a. can do.

However, since the gamma ray collimeter 32 is used to detect only the gamma rays emitted in a specific direction (direction toward the position-sensitive gamma ray detector 31) among the gamma rays emitted from each activation member 11. The total amount of gamma rays detected by the individual gamma ray measuring instrument 22 is smaller than the dose of gamma rays detected by the absolute gamma ray measuring instrument 21.

Therefore, in the measured value calibration unit 23 (see FIG. 2) of the activation amount measuring device 2, the absolute value of the gamma ray emitted from the plurality of activation members 11 calculated from the detection result by the gamma ray absolute value measuring device 21 is calculated. Use it to calibrate (S05). This makes it possible to calculate the dose of gamma rays emitted from each of the plurality of activation members 11.

If the calibration using the absolute value of the gamma ray detected by the gamma ray absolute value measuring device 21 is not performed, the amount of activation may be calibrated by another method. For example, the arrangement of the activation member 11, the shape and arrangement of the gamma ray collimator 32, and the radiation emitted from the activation member 11 reach the position-sensitive gamma ray detector 31 through the hole 32a of the gamma ray collimator 32. The ratio of radiation may be obtained in advance by simulation or the like, and the result may be used to calibrate the amount of radiation. Further, by measuring gamma rays from a radiation source having a known dose in advance, the amount of activation may be calibrated using the measurement results.

When the position-sensitive gamma-ray detector 31 is used as shown in FIG. 3, it is preferable that the position resolution is slightly larger than the size of the activation member 11. By adjusting the position resolution as described above, the detection accuracy can be improved.

Next, FIG. 4 describes another embodiment of the measurement by the gamma ray absolute value measuring device 21 and the measurement by the gamma ray individual measuring device 22.

In the embodiment shown in FIG. 4, the measurement by the gamma ray absolute value measuring device 21 and the measurement by the gamma ray individual measuring device 22 are simultaneously performed on both sides of the neutron measuring member 1. The gamma ray measurement from each activation member 11 of the neutron measuring member 1 by the gamma ray detector as the gamma ray absolute value measuring device 21 at the lower part of the drawing of the neutron measuring member 1 is the same as the embodiment shown in FIG.

On the other hand, in the upper part of the drawing of the neutron measuring member 1, only the single channel type single channel gamma ray detector 33 (radiation detector) and the gamma rays from one activation member 11 reach the single channel type gamma ray detector 33. An individual gamma ray measuring instrument 22 is provided which has a hole 34a to be made to be formed and a shielding member 34 which shields gamma rays from another activating member 11. In such a gamma ray individual measuring instrument 22, the neutron measuring member 1 has a hole 34a of the shielding member 34 in which the hole 34a corresponding to only one of the plurality of activating members 11 is formed. Detects radiation (gamma rays) emitted from each of the activation members 11 and waveguideed through the hole 34a of the shielding member 34 in a state where the activation member of one of the plurality of activation members 11 is in contact with the radiation member 11. do.

After that, by changing the relative position between the gamma ray individual measuring instrument 22 and the neutron measuring member 1, the gamma rays from the other activating member 11 can be detected individually. Specifically, the gamma-ray individual measuring instrument 22 is moved with the neutron measuring member 1 fixed, or the neutron measuring member 1 is moved with the gamma-ray individual measuring instrument 22 fixed. As a result, it is possible to detect the radiation (gamma ray) emitted from the other activation member 11 and guided through the hole 34a of the shielding member 34. By repeating this step, the radiation from each activation member 11 of the neutron measurement member 1 can be detected individually.

After detecting gamma rays from a plurality of activation members 11 individually, the gamma ray absolute value measuring device is used in the measured value calibration unit 23 (see FIG. 2) of the activation amount measuring device 2 in the same manner as in the embodiment shown in FIG. Calibration is performed using the absolute value of the gamma ray emitted from the plurality of activation members 11 calculated from the detection result in 21 (S05). This makes it possible to calculate the dose of gamma rays emitted from each of the plurality of activation members 11.

As in the examples shown in FIGS. 3 and 4, the absolute value of gamma rays from each activation member 11 of the neutron measuring member 1 is measured by the gamma ray absolute value measuring device 21 at the lower part of the drawing of the neutron measuring member 1. It is not necessary to simultaneously measure the gamma rays from each activation member 11 of the neutron measuring member 1 by the gamma ray individual measuring device 22 in the upper part of the drawing. Therefore, for example, the calibration may be performed in which the absolute value of the gamma ray from each activation member 11 is measured and then the gamma ray from each activation member 11 is individually measured. However, since the amount of gamma rays emitted changes depending on the elapsed time from activation, it is preferable to evaluate by combining the elapsed time and the like.

As described above, according to the neutron measuring member 1 according to the present embodiment, since the plurality of activating members 11 are fixed to the fixing portion 12 at predetermined intervals, the plurality of activating members 11 are individually fixed. It becomes possible to appropriately arrange the activation member as compared with the case of arranging it at a desired position. Therefore, it is possible to measure the distribution of neutrons with high accuracy.

Further, when the fixed portion 12 is a sheet-shaped member having plasticity as in the above-mentioned neutron measuring member 1, the fixed portion can be deformed according to the shape or the like of the place where the neutron is to be measured. .. Therefore, it is possible to make a sound that accurately measures the distribution of neutrons regardless of the location of the measurement target.

Further, according to the activation amount measuring method shown in FIG. 3, the gamma ray collimeter 32 in which a plurality of holes 32a are formed at the same interval as the interval in which the plurality of activation members 11 are fixed in the neutron measuring member 1 is used. The radiation emitted from each of the plurality of activation members 11 can be individually detected by the position-sensitive gamma-ray detector 31. Therefore, the amount of activation of the plurality of activation members 11 of the neutron measurement member 1 can be individually and accurately measured.

Further, according to the activation amount measuring method shown in FIG. 4, a shielding member 34 having a hole corresponding to only one of the plurality of activation members 11 of the neutron measuring member 1 is used. Then, after the radiation emitted from the activation member 11 of one of the plurality of activation members is detected by the single channel type gamma ray detector 33, the activation member that comes into contact with the hole 34a of the shielding member 34 is one member. Change from to another member and perform measurement. With such a configuration, it is possible to individually detect the radiation emitted from each of the plurality of activation members. Therefore, the amount of activation of a plurality of activation members of the neutron measurement member can be individually and accurately measured.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

For example, in the above embodiment, the case where the radiation emitted from the activated activation member 11 is gamma rays has been described, but the type of radiation emitted from the activation member 11 is not particularly limited.

Further, the shapes of the gamma ray collimator 32 and the shielding member 34 for individually detecting the radiation emitted from the activated activation member 11 are not particularly limited.

1 ... neutron measuring member, 2 ... activation amount measuring device, 11 ... activating member, 12 ... fixed part, 21 ... gamma ray absolute value measuring device, 22 ... gamma ray individual measuring device, 23 ... measured value calibration unit, 31 ... position Sensitive gamma ray detector, 32 ... gamma ray collimeter, 33 ... single channel gamma ray detector, 34 ... shielding member.

Claims (4)

A device for measuring the amount of activation, including a neutron measuring member and a device for measuring the amount of activation.
The neutron measuring member is
Multiple activation members made of metal that are activated by irradiation with neutron rays,
A fixing portion in which the plurality of activating members are fixed at predetermined intervals,
Have,
The activation amount measuring device is
A gamma-ray collimator in which a plurality of holes are formed at the same interval as the interval at which the activation member is fixed,
A radiation detector that individually detects radiation guided through the plurality of holes, and
Have,
Each of the plurality of holes of the gamma ray collimator individually corresponds to one of the plurality of activation members which is different from each other.
The gamma-ray collimator corresponds to each of the plurality of holes when one of the plurality of activation members corresponding to the hole is brought into contact with each other individually and simultaneously. A device that measures the amount of activation that prevents radiation emitted from an activation member different from the member from entering the hole . A device for measuring the amount of activation, including a neutron measuring member and a device for measuring the amount of activation.
The neutron measuring member is
Multiple activation members made of metal that are activated by irradiation with neutron rays,
A fixing portion in which the plurality of activating members are fixed at predetermined intervals,
Have,
The activation amount measuring device is
A hole corresponding to only one of the plurality of activation members is formed, and when a specific activation member is brought into contact with the hole, the radiation emitted from the other activation member is shielded. Shielding member and
A radiation detector that detects the radiation guided through the hole, and
A device for measuring the amount of activation. It is a method of measuring the amount of activation of neutron measuring members.
Neutron measurement after neutron irradiation, which has a plurality of activation members made of metal activated by irradiation with neutron rays and a fixed portion in which the plurality of activation members are fixed at predetermined intervals. The process of preparing the parts and
The plurality of activation members of the neutron measuring member are individually provided for each of the plurality of holes of the gamma ray collimator in which the plurality of holes are formed at the same interval as the interval at which the activation member is fixed. The process of contact and
A step of individually detecting radiation emitted from each of the plurality of activation members and guided through each of the plurality of holes by a radiation detector.
Have,
Each of the plurality of holes of the gamma ray collimator individually corresponds to one of the plurality of activation members which is different from each other.
The gamma-ray collimator corresponds to each of the plurality of holes when one of the plurality of activation members corresponding to the hole is brought into contact with each other individually and simultaneously. A method for measuring the amount of activation that prevents radiation emitted from an activation member different from the member from entering the hole . It is a method of measuring the amount of activation of neutron measuring members.
Neutron measurement after neutron irradiation, which has a plurality of activation members made of metal activated by irradiation with neutron rays and a fixed portion in which the plurality of activation members are fixed at predetermined intervals. The process of preparing the parts and
A hole corresponding to only one of the plurality of activation members is formed, and when a specific activation member is brought into contact with the hole, the radiation emitted from the other activation member is shielded. In a state where one of the plurality of activation members of the neutron measuring member is in contact with the hole of the shielding member, the radiation is emitted from the one activation member of the shielding member. The process of detecting the radiation directed through the hole with a radiation detector,
The activation member in contact with the hole of the shielding member is changed to another activation member different from the one activation member, and is discharged from the other activation member to guide the hole of the shielding member. The process of detecting the waved radiation with the radiation detector,
A method for measuring the amount of activation.

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