JP2000187077A - Apparatus and method for detection of two-dimensional radiation image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an apparatus and a method in which the pulse-height shape of a light emitting signal in a multichannel is changed easily into a time based shape and a digital signal by a method wherein, when a signal is detected by using an optical fiber so as to find a two-dimensional radiation image, a streak camera method is used. SOLUTION: An ionizing radiation is converted into light by a radiation detecting body in which a plastic scintillator is made sheetlike. An optical fiber bundle is arranged to be a face shape on the rear of the radiation detecting body in order to detect fluorescence. An optical system arranges beams of light radiated from both ends of the optical fiber bundle to be a transversely parallel shape, and the width of the beams of light corresponding to their transverse width can be made variable. A streak tube which is time-swept at high speed detects the output light of the optical system in a multichannel. An imaging camera images a streak image which is output to the streak tube. A signal processing analyzer digitizes its image signal so as to be stored as data in which the intensity of a light emitting signal is changed into a time-series shape. It is analyzed and processed, and a two-dimensional radiation image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a two-dimensional radiation image by detecting radiation using a luminous body as a radiation detector, and more particularly to a method for detecting a change in luminescence emitted from the luminous body at high speed. In addition, by reading and analyzing as digitized data with no dead time and time-series data of emission signal intensity, even if radiation enters at a high incidence rate, a two-dimensional radiation image can be accurately read with a simple device. It is a method. For this reason, medical X-ray diagnosis using X-ray generators and accelerators,
It is used for high-speed processing such as X-ray or neutron-based autoradiography, and for grasping dynamic events using real-time radiation image detection. It is used for radiation image detectors for energy physics research, as well as high-performance distribution monitoring devices for radiation including neutrons in nuclear reactors and fusion reactors.

[0002]

2. Description of the Related Art In the prior art, various signal detection methods of a two-dimensional radiation image detector using a luminous body, a luminous gas, or a luminous liquid using an optical fiber such as a wavelength shifter have been devised and used. However, when converting light into an electric signal, as shown in FIG. 12, it is composed of a photomultiplier tube, an amplifier circuit for amplifying the signal, and a wave height discrimination circuit for extracting the timing of the signal. It was necessary to prepare many modules and adjust the combination. In addition, in order to convert electric signals at high speed and to digitize them, an ultra-high-speed analog-to-digital converter is required in place of the wave height discrimination circuit, which further complicates the system and increases the cost and area. It is enormous every time resolution is improved.

On the other hand, the streak camera method has conventionally been used for reading out signals from a one-dimensional detector by utilizing its high speed, and has been used for measuring signal strength and timing.
An example in which a streak method as shown in FIG. 13 is used for two-dimensional measurement [JCCheng et al., Fiber arry technique
for subnanosecond X-ray framing camera, CONF-7608
28-10], but it has been difficult to achieve a large area and a high positional resolution because all optical signals at two-dimensional positions are input to the streak tube.

[0004]

According to the present invention, a luminous body,
Alternatively, when detecting a signal using an optical fiber such as a wavelength shifter in a two-dimensional radiation image detector using a luminescent gas or a luminescent liquid to obtain a two-dimensional radiation image, it is difficult with the conventional method as described above. High-speed acquisition of multi-channel optical signal crest shapes, signal processing and analysis to improve position resolution and enable high-speed processing to achieve large area, high position resolution or two performances. It is an object of the present invention to provide a detection device and a method thereof capable of performing a combined two-dimensional radiation image at high speed and easily. It is another object of the present invention to provide a detection device and a method thereof that can easily and quickly perform two-dimensional neutron images of neutrons as well as ionizing radiation.

[0005]

According to the present invention, there is provided a two-dimensional radiation image detector using a luminous body, a luminous gas, or a luminous liquid, in which a signal is detected using a wavelength shifter or the like. Is performed, a streak camera method is used in order to easily time-sequentially convert the crest shapes of the emission signals of the multi-channels into a digital signal and obtain a digital signal. Since the peak shape of the emission signal can be time-series and digitized at high speed, the time signal or signal intensity can be obtained with high accuracy by analyzing this time-series data, and thus the radiation incident position can be accurately obtained in two dimensions. You can ask. In addition, since the peak shape can be measured accurately, even when radiation enters the detector at a high incidence rate, it is possible to decompose the piled-up and superimposed peak shape and determine the respective time signal or signal strength. Thus, it is possible to configure a two-dimensional radiation image detector that can support high counting rate measurement of radiation. Furthermore, in the streak camera method, by using a streak tube and an image sensor, signal processing circuits such as a photomultiplier tube, an amplifier, and an analog / digital converter, which are required for the number of optical signal channels, can be replaced. It is possible to configure a two-dimensional radiation image detector with a small number of simple devices and easy maintenance.

On the other hand, since the wave form of a continuously generated light emission signal can be collected at a high speed, the radiation detector detects the light emission signal intensity of light output from both ends of the optical fiber based on time-series data. The difference between the time it takes for the light emission to reach each end of each optical fiber in the horizontal direction and the vertical direction, and the intensity of each, are analyzed, and the radiation detection object is analyzed by combining the horizontal and vertical directions, the arrival time difference, and the intensity difference. A two-dimensional radiation image can be obtained by finding the position of ionizing radiation incident on the object.

Further, based on the fact that the optical fibers are arranged in a lattice, the light emitted in one lattice in the radiation detector is separated from the two optical fibers in the horizontal direction corresponding to the lattice by the vertical direction. By applying the simultaneous measurement method utilizing the detection by the two optical fibers, the incident position of ionizing radiation on the radiation detector can be obtained, and a two-dimensional radiation image can be obtained.

In the above-mentioned apparatus, a two-dimensional radiation image is continuously obtained by continuously detecting and storing operations using two or more imaging cameras for detecting and storing streak images obtained on the fluorescent screen of the streak tube. Can be detected.

On the other hand, Gd, ⁶ which is a neutron converter material for converting neutrons into ionizable radiation in the radiation detector.
A two-dimensional neutron image can be obtained by using a neutron detector containing at least one kind of Li, ¹⁰ B or ³ He, or a mixture or a combination.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a two-dimensional radiation image detector using a luminous body, a luminous gas, or a luminous liquid, signal detection is performed using an optical fiber such as a wavelength shifter to obtain a two-dimensional radiation image. By using the streak camera method, it is possible to time-series and digitize the crest shape at high speed with a simple device,
A two-dimensional radiation image detector capable of two-dimensionally detecting a radiation incident position with high accuracy and supporting high counting rate measurement can be configured.

Further, the crest shapes of the emission signals output from both ends of the optical fiber, which are continuously generated, are collected at high speed, and based on the time-series data of the intensity of the emission signal, the waveform of the emission signal reaches the ends of the optical fiber. The position detection method using the time difference of each time and the respective intensity difference, and the position detection method using the arrangement of the optical fibers in a lattice can be easily and accurately applied. Can be obtained.

By using two or more imaging cameras for detecting and storing streak images, a two-dimensional radiation image can be continuously detected.

On the other hand, a two-dimensional neutron image can be obtained by using the neutron converter material and the luminous body in combination.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment, a sheet-like radiation detector for converting ionizing radiation into light according to the present invention,
An optical fiber bundle arranged in a plane on the rear surface of the radiation detector,
2 consisting of a device for detecting light from the optical fiber bundle, processing and analyzing the signal, and forming a two-dimensional image of radiation
The three-dimensional radiation image detection device will be described with reference to FIG.

The two-dimensional radiation image detecting apparatus according to the present embodiment has a sheet-like radiation detecting body made of a plastic scintillator for converting ionizing radiation into light, and an optical fiber for detecting fluorescence on the rear surface. The optical fiber bundle and the light emitted from both ends of the optical fiber bundle are arranged side by side in parallel, an optical system that can change the width of light corresponding to the arranged width, and a light that is output from the optical system are multiplied. Streak tube detected by channel, control circuit that sweeps the streak tube with time at high speed, imaging camera that captures streak images output to the streak tube, and digitization of video signal of imaging camera, time series of emission signal intensity A signal processing / analyzing device is stored as the converted data, and the data is analyzed and processed into a two-dimensional radiation image.

A plastic scintillator used as a material of a sheet-shaped radiation detector is a plastic scintillator B manufactured by Bicron, USA, which has been conventionally used as a medium for detecting ionizing radiation such as X-rays or α-rays.
CF-12 or the like can be used. The fluorescence lifetime is 3.2 ns. When the plastic scintillator BCF-12 is used, a central wavelength of 435 nm is emitted when ionizing radiation is incident. Therefore, a wavelength-shifted optical fiber sensitive to 435 nm light is used as an optical fiber arranged in a plane. . As this wavelength-shifting optical fiber, BCF-92 manufactured by Bicron, USA, or the like can be used. BCF-92
In the case of 435 nm, the center wavelength of the incident 435 nm fluorescence is 490 n.
m and is output from both ends of the optical fiber. The diameter of the optical fiber is desirably 0.1 mm or more because the position resolution of the detector and the fluorescence detection efficiency are closely involved. The length of the optical fiber is determined according to the detection area of the sheet-shaped radiation detector.

The detection area of the sheet-shaped radiation detector is 20 cm in width and 100 cm in height. At this time, the diameter 1
100 mm wavelength-shifted optical fibers are arranged on the rear surface of a sheet-shaped radiation detector at intervals of 2 mm. At this time, the horizontal position resolution is 2 mm at best. The length of the wavelength-shifted optical fiber is set to 3 m in consideration of the sensitive portion being 100 cm and the extension portions at both ends. After the two ends of the wavelength-shifted optical fiber bundle are arranged side by side in parallel, the width of the bundle is adjusted to a sensitive width of the streak tube by an optical system such as a lens. When the sensitive part of the horizontal width of the streak tube is short, the optical fiber bundles at both ends can be used in two stages, and the vertical width of the streak tube, that is, the effective length of the time axis can be reduced to half. When the sensitive portion of the streak tube is short, one optical fiber bundle can be divided to increase the number of stages. However, in this case, it is necessary to determine the position resolution in consideration of the fact that the effective length of the time axis becomes short and that there is a time difference between the time-series data.

As the streak tube, it is necessary to select a type having a sensible portion as large as possible in width, and a Hamamatsu Photonics C4187 having a length of 25 mm as a sensitive length.
Etc. can be used. In this case, the reduction ratio of the optical system using a lens or the like is 1/8 because the width of each optical fiber bundle is 10 cm and the two are arranged in parallel.
is necessary.

The wavelength-shifted emission signal reduced by the optical system and entered the sensitive portion of the streak tube is converted by the control circuit of the streak tube into a deflection voltage of the deflection plate of the streak tube at a time interval shorter than the emission life of the radiation detector. Is swept and detected for a time corresponding to the vertical width of the streak tube. When the plastic scintillator BCF-12 is used as the light emitter, the fluorescence lifetime is 3.2 ns. Therefore, when the waveform shape is divided into 32, the time resolution which is the resolution on the vertical axis is 0.1 n.
s. At this time, if the effective light propagation speed in the optical fiber is half of the high speed, a position resolution of 1.5 cm can be obtained. After a time sweep corresponding to the vertical width, a streak image can be obtained on the fluorescent screen of the streak tube, and this streak image is captured by an imaging camera. CCD with a detection characteristic of 1,000 pixels horizontally and 1,000 pixels vertically as an imaging camera
A camera can be used. At this time, the effective sweep time is 100 ns by multiplying 0.1 ns by 1000 since the number of pixels on the vertical axis of the CCD camera is 1000 pixels. CC
By digitizing the video signal of the D camera by the signal processing / analysis device, time-series data of the two optical fiber bundles can be obtained. This data is stored in a storage device in the signal processing / analyzing device.

The stored time-series data of the light emission signal intensity at both ends of the optical fiber bundle are analyzed by a signal processing / analyzing device. The peak shape of each light emission is analyzed based on the time-series data of the light emission signal intensity of the light output from both ends of the optical fiber. When the plastic scintillator BCF-12 is used as the luminous body, the fluorescence lifetime is 3.2 ns and the time resolution is 0.1 ns as in the embodiment, so that the peak shape can be measured accurately. For this reason, even when radiation enters the detector at a high incidence rate and is piled up and overlapped by two or more, it is necessary to analyze the wave height shape and decompose it into light emission shapes to obtain the respective time signal or signal intensity. It is possible. Further, when analyzing, one standard wave height shape is recorded in advance, and separation can be performed with high accuracy based on this data. Thus, by analyzing the peak shape of the light emission, the light emission time and the light emission intensity of each light emission can be obtained. Therefore, a two-dimensional radiation image detector capable of coping with the high counting rate measurement of radiation can be configured including the embodiments described below.

Based on the analysis results, the difference in the time required for the light emission in the radiation detector to reach both ends of each optical fiber and the respective intensities are attenuated due to poor light transmittance in the case of a plastic scintillator or the like. It can be obtained by using a generally known method utilizing the fact. Also,
It is also possible to obtain a two-dimensional radiation image by performing analysis processing based on the time difference or the light emission intensity difference or by combining the time difference and the intensity difference to obtain the position of ionizing radiation incident on the radiation detector.

In the present embodiment, a sheet-like radiation detector is used, but a plate-like detection medium using a single crystal scintillator such as CsI (Tl) or a glass scintillator such as Li glass can also be used.

In a second embodiment, a two-dimensional image of radiation is obtained by detecting light from an optical fiber bundle in which radiation-sensitive fibers made of a material emitting light by ionizing radiation are arranged in a plane and performing signal processing and analysis. 2 will be described with reference to FIG.

As an embodiment, the detection medium is replaced with the radiation-sensitive fiber from the wavelength-shifted optical fiber bundle shown in the first embodiment, and the other streak cameras and signal processing / analysis devices are the first described embodiments. It has the same configuration, and the method for obtaining the light emission position is the same.

As the radiation-sensitive fiber, a plastic scintillator fiber manufactured by Bicron Inc. of the United States can be used, and BCF-1 is used for detecting X-rays or particle beams.
Optical fibers such as 2 can be used.

As a third embodiment, a streak camera and two optical fiber bundles composed of a large number of optical fibers arranged in a lattice on the back surface of a radiation detector in the form of a sheet or a plate, which converts ionizing radiation into light. A two-dimensional radiation image detecting apparatus using the method will be described with reference to FIG.

A sheet-shaped radiation detector coated with a powdery phosphor for converting ionizing radiation into light is arranged on the rear surface of the radiation detector in a grid pattern at intervals corresponding to the positional resolution in the horizontal and vertical directions. An optical system capable of arranging two optical fiber bundles composed of a large number of optical fibers and one end of an optical fiber bundle arranged in a horizontal direction and a vertical direction in parallel in a horizontal direction, and changing a light width corresponding to the arranged horizontal width. A streak tube for detecting light output from the optical system in a multi-channel manner, a control circuit for quickly sweeping the streak tube with time, an imaging camera for capturing a streak image output to the streak tube, and an image of the imaging camera. The signal is digitized and stored as time-series data of the emission signal intensity.
It consists of a signal processing / analyzing device that produces a two-dimensional radiation image.

In an embodiment, a powdery phosphor used as a material of a sheet-shaped radiation detector is ZnS: Ag, which has been conventionally used as a medium for detecting ionizing radiation such as X-rays or α-rays. Can be used. The fluorescence lifetime is 0.2 μs. When ZnS: Ag is used as the detection medium, the center wavelength is 450 nm when ionizing radiation is incident.
The two optical fiber bundles that are arranged in a grid at intervals corresponding to the positional resolution in the horizontal and vertical directions on the rear surface of the radiation detector to emit light at a wavelength of 450 nm are wavelength-shifted optical fibers sensitive to 450 nm light. BCF manufactured by Bicron, USA
-92 or the like can be used. In the case of BCF-92, the incident fluorescence of 450 nm is converted into light having a center wavelength of 490 nm and output from both ends of the optical fiber. The diameter of the optical fiber is desirably 0.1 mm or more because the position resolution of the detector and the fluorescence detection efficiency are closely involved. The length of the optical fiber is determined according to the detection area of the sheet-shaped radiation detector. The detection area of the sheet-shaped radiation detector is 20 cm in width and 20 cm in height. At this time, a diameter of 1 mm is formed in a grid at intervals corresponding to the position resolution in the horizontal and vertical directions.
Are arranged in the horizontal and vertical directions on the rear surface of the radiation detector in the form of 100 sheets at 2 mm intervals. The length of this wavelength-shifted optical fiber is 2
The length is set to 2 m in consideration of 0 cm and the extended portions at both ends. After arranging one end of the horizontal and vertical wavelength-shifted optical fiber bundles side by side in parallel, the width of the bundle is adjusted to an insignificant width of the streak tube by an optical system such as a lens.

As the streak tube, a sensitive length of 25 is used.
Hamamatsu Photonics C4187 having a length of mm can be used. The control circuit of the streak tube sweeps the deflection voltage of the deflection plate of the streak tube at a time interval shorter than the emission life of the radiation detector for a time corresponding to the vertical width of the streak tube to detect. When ZnS: Ag is used as the luminous body, the waveform shape is 1 because the fluorescence lifetime is 0.2 μs.
When dividing by 0, the time resolution which is the resolution on the vertical axis is 20
ns. After a time sweep corresponding to the vertical width, a streak image can be obtained on the fluorescent screen of the streak tube, and this streak image is captured by an imaging camera. Horizontal 1 for imaging camera
A CCD camera having a detection characteristic of 000 pixels and 1,000 pixels vertically can be used. At this time, the effective sweep time is 20 μs by multiplying 20 ns by 1000 because the number of pixels on the vertical axis of the CCD camera is 1000 pixels. By digitizing the image signal of the CCD camera by the signal processing / analyzing device, time-series data of the two optical fiber bundles can be obtained. This data is stored in a storage device in the signal processing / analyzing device.

Based on the time-series data of the emission signal intensity of the light output from one end of each of the horizontal and vertical optical fibers stored in the signal processing / analyzing device, the ionizing radiation to the radiation detector is determined. Find the incident position. The light emission time and the light emission intensity can be obtained by analyzing the peak shape of the light emission based on the time-series data of the light emission signal intensity. Based on the calculated light emission time of each optical fiber in the horizontal and vertical directions,
Based on the fact that the optical fibers are arranged in a grid on the rear surface of the sheet-shaped radiation detector, one
Injection of ionizing radiation into the radiation detector by utilizing the fact that light emitted in one lattice is detected by two horizontal optical fibers and two vertical optical fibers corresponding to the lattice. The position can be determined and a two-dimensional radiation image can be obtained.

Although the sheet-like radiation detector is used in this embodiment, a plate-like detection medium using a single crystal scintillator such as CsI (Tl) or a glass scintillator such as Li glass can be used.

Fourth Embodiment As a fourth embodiment, a two-dimensional radiation image detecting apparatus using a radiation detector having a plate-like transparent luminous body for converting ionizing radiation into light, a horizontal and vertical optical fiber bundle, and a streak camera. About FIGS. 4 and 5
It is described based on. As shown in FIG. 4, the detection portion of the present detection device has a plate-shaped radiation detector that converts a transparent luminous body that converts ionizing radiation into light, and a grid-like detector that contacts four side surfaces of the radiation detector. , And a horizontal optical fiber and a vertical optical fiber. A large number of optical fibers in the horizontal and vertical directions are arranged in parallel to form a bundle of optical fibers in the horizontal and vertical directions. One ends of the optical fiber bundles in the horizontal direction and the vertical direction are arranged side by side as shown in the overall view of FIG. The width of light from the optical fiber bundles arranged in parallel in the horizontal direction and the vertical direction is adjusted by using an optical system having a variable width, such as a lens, and the light is incident on the sensitive part of the streak tube.

As an embodiment, an inorganic scintillator, L, is used as a radiation detector having a transparent luminous body in a plate shape.
i ₆ Gd (BO ₃ ) ₃ : 5 cm x 5 cm made of Ce
Can be used. The thickness is 3 mm. The scintillation detectors are arranged in 40 rows horizontally and 40 rows vertically, that is, 16 rows of 40 × 40.
With a detection area of about 2 m in width and about 2 m in height,
A three-dimensional radiation image detection device. A horizontal optical fiber and a vertical optical fiber are arranged in a lattice so as to be in contact with the four side surfaces of the radiation detector. As the optical fiber, the radiation detector Li ₆ Gd (BO ₃ ) ₃ : C
Since e emits light of 385 nm, BCF- manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to this light, is used.
92 optical fibers are used. The diameter of the wavelength shift fiber is 1 mm, and the length is 5 m in consideration of the extension. 490 nm light is output from this wavelength shift fiber.

As the streak tube, a sensitive length of 25
Hamamatsu Photonics C4187 having a length of mm can be used. In this case, the reduction ratio of the optical system using a lens or the like needs to be reduced to 3.2 times since the length of each optical fiber bundle is 4 cm and the two are arranged in parallel.

The wavelength-shifted emission signal reduced by the optical system and entered into the sensitive portion of the streak tube is subjected to the deflection voltage of the deflection plate of the streak tube by the control circuit of the streak tube at a time interval shorter than the emission life of the radiation detector. Is swept and detected for a time corresponding to the vertical width of the streak tube. When the waveform of the inorganic scintillator Li ₆ Gd (BO ₃ ) ₃ : Ce is 200 ns and the waveform shape is divided into ten, the time resolution, which is the resolution on the vertical axis, is 20 ns. After a time sweep corresponding to the vertical width, a streak image can be obtained on the fluorescent screen of the streak tube, and this streak image is captured by an imaging camera. As an imaging camera, a CCD camera having a detection characteristic of 1,000 pixels horizontally and 1,000 pixels vertically can be used. At this time, the effective sweep time is CCD
20n because the number of pixels on the vertical axis of the camera is 1000 pixels
s is multiplied by 1000 to become 20 μs. By digitizing the image signal of the CCD camera by the signal processing / analyzing device, time-series data of the two optical fiber bundles can be obtained. This data is stored in a storage device in the signal processing / analyzing device.

Based on the time-series data of the light emission signal intensity of the light output from the optical fiber, the peak shape of each light emission can be analyzed to determine the light emission time. Based on the emission time of each optical fiber in the horizontal and vertical directions obtained by the analysis, the radiation detection inside the radiation detection The light emitted within one of the grids is a horizontal 2 corresponding to the grid.
The two-dimensional radiation image can be obtained by obtaining the incident position of ionizing radiation on the radiation detector by utilizing the detection by the optical fiber and the two optical fibers in the vertical direction. As an example in which the position of the image detection device is determined with higher accuracy, a case where a plastic scintillator is used as a radiation detector having a transparent light-emitting body in a plate shape will be described. As a detection medium,
A plastic scintillator BCF-12 manufactured by Bicron, USA, which has been conventionally used as a medium for detecting ionizing radiation such as X-rays or α-rays, is used. Fluorescence lifetime is 3.2
ns.

This plastic scintillator BCF-1
5 is used as a detection medium. The thickness is 3 mm. Using about 40 horizontal rows and 40 vertical rows, or 1600 40 × 40 scintillation detectors, about 2
m, a two-dimensional radiation image detection device having a detection area of about 2 m in length. A horizontal optical fiber and a vertical optical fiber are arranged in a lattice so as to be in contact with the four side surfaces of the radiation detector. As the optical fiber, since the radiation detector BCF-12 emits light of 435 nm,
A BCF-92 optical fiber manufactured by Bicron, USA, which is a wavelength shift fiber sensitive to this light, is used. The diameter of the wavelength shift fiber is 1 mm, and the length is 5 m in consideration of the extension. 490 nm from this wavelength shifting fiber
Is output.

As the streak tube, a sensitive length of 25 is used.
Hamamatsu Photonics C4187 having a length of mm can be used. In this case, the reduction ratio of the optical system using a lens or the like needs to be reduced to 3.2 times since the length of each optical fiber bundle is 4 cm and the two are arranged in parallel.

The wavelength-shifted emission signal reduced by the optical system and entered the sensitive portion of the streak tube is converted by the control circuit of the streak tube into a deflection voltage of the deflection plate of the streak tube at a time interval shorter than the emission life of the radiation detector. Is swept and detected for a time corresponding to the vertical width of the streak tube. When the waveform shape is divided into 32 since the fluorescence lifetime of the luminous body BCF-12 is 3.2 ns, the time resolution, which is the resolution on the vertical axis, is 0.1 ns. After a time sweep corresponding to the vertical width, a streak image can be obtained on the fluorescent screen of the streak tube, and this streak image is captured by an imaging camera. As an imaging camera, a CCD camera having a detection characteristic of 1,000 pixels horizontally and 1,000 pixels vertically can be used. At this time, the effective sweep time is 1 pixel on the vertical axis of the CCD camera.
000 pixels, 0.1 ns is multiplied by 1000 to 100
ns. By digitizing the image signal of the CCD camera by the signal processing / analyzing device, time-series data of the two optical fiber bundles can be obtained. This data is stored in a storage device in the signal processing / analyzing device.

The stored time-series data of the light emission signal intensity at both ends of the optical fiber bundle are analyzed by a signal processing / analyzing device. The peak shape of each light emission is analyzed based on the time-series data of the light emission signal intensity of the light output from the optical fiber. When a plastic scintillator is used as the light-emitting body, the fluorescence lifetime is 3.2 ns, and the pulse height shape can be analyzed with high accuracy because the time series is 0.1 ns as the time accuracy as in the embodiment. For this reason, even when radiation enters the detector at a high incidence rate and is piled up and overlapped by two or more, it is necessary to analyze the wave height shape and decompose it into each light emission shape to obtain the respective light emission time or signal intensity. It is possible.

Based on the light emission time of each optical fiber in the horizontal and vertical directions obtained by this analysis, a plastic scintillator as a radiation detector having a transparent illuminant in a plate shape, and an optical fiber Is arranged, and the light emitted in one lattice shape in the radiation detection body is detected by two lateral optical fibers and two longitudinal optical fibers corresponding to each lattice, thereby detecting radiation. The incident position of ionizing radiation on the body can be determined to obtain a two-dimensional radiation image. At this time, two optical fibers in the horizontal direction corresponding to each lattice of the optical fibers arranged in a lattice and two
The time at which the intensity of the light emission signal in the four optical fibers is maximized is determined based on the time-series data of the optical fibers, and the light emitted in one grid in the radiation detector is detected. In this case, the fact that the light emission times in the four optical fibers coincide within the time corresponding to the set grating length of 5 cm is used. Assuming that the effective propagation speed of light in the optical fiber is half of the high speed, the time corresponding to the set grating length is 5c.
This corresponds to about 0.3 ns in m. As described above, since the accuracy of the light emission time obtained in this embodiment is 0.1 ns,
By applying the coincidence method of four signals with 0.3 ns as the shortest resolution time, the position where light is emitted within the radiation detector can be determined with extremely high accuracy, and a two-dimensional radiation image can be obtained.

As a fifth embodiment, a case in which a gas that is ionized and emits light by ionizing radiation is used as a radiation detector will be described with reference to FIG. As shown in the figure, a container for containing gas, two optical fiber bundles composed of a large number of optical fibers mounted in a lattice in the horizontal and vertical directions in the container, and an optical fiber bundle arranged in the horizontal and vertical directions. One end is arranged side by side in parallel, an optical system that can change the width of light corresponding to the arranged width, a streak tube that detects light output from the optical system in multiple channels, and a high-speed sweep of the streak tube Control circuit, an imaging camera that captures a streak image output to the streak tube, and a video signal of the imaging camera that is digitized and stored as time-series data of the emission signal intensity. It consists of a signal processing / analyzing device that produces a two-dimensional radiation image.

Ar gas or the like can be used as a gas that receives ionizing radiation and ionizes to emit light.

For the optical fiber bundle for detecting light emission, the streak camera, and the signal processing / analyzing device, the same device as that of the third embodiment can be used, and the same detecting method can be used.

In the fifth embodiment, an example in which only gas emission is used is shown. In the sixth embodiment, a metal wire is stretched in a lattice shape in a detection body and a high voltage is applied to perform gas amplification in the gas. An example of use is shown based on FIG. 7 and FIG.

FIG. 7 shows a gas used as a radiation detector, which is ionized by ionizing radiation and emits light, a container for enclosing the gas, a wire stretched in the container at a predetermined interval, and a high voltage applied to the wire. A high-voltage power supply, a vertical optical fiber bundle in which optical fibers are stretched so that the wires stretched in the container at the center become the center, and bundled outside the container, and the container is stretched at a right angle to these optical fibers at regular intervals. 3 shows a configuration of a detection unit including a bundle of optical fibers in a lateral direction bundled outside. As shown in the overall view of FIG. 8, when a high voltage is applied from a high-voltage power supply to a wire stretched in a container and ionizing radiation is incident to ionize a gas or liquid, light emitted from the gas or liquid is amplified and the emitted light is laterally changed. The light emitted from one end of each of the optical fiber bundles in the horizontal and vertical directions is condensed by the optical fiber bundles in the vertical and vertical directions, and the light emitted from one end of each optical fiber bundle in the horizontal and vertical directions is arranged side by side in parallel. Optical system that can change the wavelength, a streak tube that detects light output from the optical system in multiple channels, a control circuit that sweeps the streak tube at high speed, and an imaging camera that captures a streak image output to the streak tube And digitizing the image signal of the imaging camera, storing the data as time-series data of the intensity of the emission signal, and analyzing the data to generate a two-dimensional radiation image.
It consists of an analyzer. Except that a high voltage is applied to the metal wire, the same apparatus as that of the fifth embodiment can be used, and the same method can be used for determining the position.

As a seventh embodiment, in order to enhance the position resolution function of the device of the third embodiment, light emitted from one end of each of the optical fiber bundles in the horizontal and vertical directions as shown in FIG. Instead of arranging them vertically or arranging them vertically,
A two-dimensional radiation image detecting apparatus in which light emitted from both ends of an optical fiber bundle is arranged side by side in four rows or two in two rows or four rows will be described. In this case, when the image signal of the imaging camera is digitized and stored by the signal processing / analyzing device and then analyzed, when the analysis processing is performed, the time series of the emission signal intensity of the light output from both ends of each optical fiber in the horizontal direction and the vertical direction is obtained. Based on the obtained data, the difference between the time required for the light emission in the radiation detector to reach both ends of each optical fiber in the horizontal direction and the vertical direction and their respective intensities are calculated, and the arrival time difference and the intensity in the horizontal and vertical directions are obtained. The difference is combined and analyzed to determine the incident position of ionizing radiation on the radiation detector and to determine a two-dimensional radiation image. In addition, a two-dimensional radiation image detection device with improved position detection accuracy and position resolution can be configured by combining the above-described methods for determining the incident position. For the other optical fiber bundle for detecting light emission, the streak camera, and the signal processing / analyzing device, the same device described in the third embodiment can be used.

In the eighth embodiment, one imaging camera has been used for detecting and storing a streak image obtained on the fluorescent screen of the streak tube. However, this embodiment will be described with reference to an example in which two or more imaging cameras are used for switching. A case in which three imaging cameras are applied based on 3 will be described with reference to FIG.

Starting from the start signal input to the control circuit of the streak tube, sweeping of the streak tube is started and the streak tube is swept to obtain a streak image on the fluorescent screen of the streak tube.
The obtained streak image is taken by the first CCD camera among the three CCD cameras. After the imaging is completed, the camera is switched to the second CCD camera by the camera switching mechanism. At the same time, the radiation signal data stored in the first CCD camera is read by the signal processing / analyzing device. By synchronizing the sweeping of the streak camera, the switching of the CCD camera, and the reading operation of the accumulated radiation signal data to the signal processing / analyzing device, the radiation data accumulated in the CCD camera is transmitted through the frame scale. It is possible to reduce the dead time during the time required for reading out and reading, and to configure a two-dimensional radiation image detecting device capable of continuously repeating detection of a two-dimensional radiation image.

[0050] In the above embodiment has been described for the detection of ionizing radiation, a neutron converter material for converting the neutron radiation detector body to ionizable radiation Gd, ⁶ L
A two-dimensional neutron image detecting apparatus characterized in that a two-dimensional neutron image is obtained by using a neutron detector containing at least one kind of i, ¹⁰ B or ³ He, or a mixture or combination thereof. Can be. In the ninth embodiment, ZnS: Ag which is a phosphor is used as a material of the radiation detector in the form of a sheet in the third embodiment, and LiF containing ⁶ Li which is a neutron converter is mixed with the ZnS: Ag to form a sheet. An example in which the detection medium is formed in a shape will be described with reference to FIG. ZnS: ^{6 for} Ag
LiF using Li is mixed and formed into a sheet to form a detection medium. When neutrons enter this detection medium, ⁶ Li causes a nuclear reaction and emits α rays. A two-dimensional neutron image can be obtained by detecting this α-ray with ZnS: Ag using the same apparatus and position determination method as in the third embodiment.

Further, the present invention is applicable to a detection medium in which a powder containing Gd, ⁶ Li or ¹⁰ B itself is a neutron detection medium in the form of a sheet or a transparent detection medium. Li ₆ Gd (B) of the radiation detector described in Embodiment 4
O ₃ ) ₃ : Ce contains these and the phosphor itself is a neutron detection medium, so that a two-dimensional neutron image detection device can be constituted as it is.

[0052]

Since the present invention is configured as described above, it has the following effects.

In a two-dimensional radiation image detector using a luminous body, a luminous gas, and a luminous liquid, when a signal is detected using an optical fiber such as a wavelength shifter to obtain a two-dimensional radiation image, a streak camera method is used. Accordingly, it is possible to time-series and digitize the peak shape of the multi-channel light-emitting signal with a simple device.

By detecting a multi-channel optical signal of a two-dimensional radiation image using a streak camera method, the optical signal is once converted into an electric signal by a photomultiplier tube and analog-to-digital conversion, which is extremely high speed. It is possible to configure a two-dimensional radiation image detector capable of two-dimensionally detecting the radiation incident position with high accuracy and measuring a high counting rate.

A radiation detector in the form of a plate made of a transparent luminous body for converting ionizing radiation into light, and a number of laterally and vertically mounted lattices in contact with the four side surfaces of the radiation detector. By using a streak camera method and a detector consisting of horizontal and vertical optical fiber bundles composed of optical fibers, a two-dimensional radiation image with a large area, high positional resolution, or a combination of two performances can be produced at high speed. A two-dimensional radiation image detector that can be easily and easily performed can be configured.

By collecting the crest shapes of the emission signals output from both ends of the two optical fiber bundles in the horizontal direction and the vertical direction at high speed, it is possible to use several position detection methods in combination. It is possible to obtain a two-dimensional radiation image with high accuracy and a high counting rate.

By switching and using two or more imaging cameras for detecting and storing the streak image, a two-dimensional radiation image can be continuously detected.

A two-dimensional neutron image can be obtained by using a combination of a neutron converter material and a luminous body which emits light by ionizing radiation.

[Brief description of the drawings]

FIG. 1 is a diagram of a two-dimensional radiation image detection apparatus using a plastic scintillator sheet of Example 1 as a radiation detector.

FIG. 2 is a diagram illustrating a two-dimensional radiation image detection apparatus using a scintillation optical fiber bundle according to a second embodiment as a radiation-sensitive fiber.

FIG. 3 is a diagram of a two-dimensional radiation image detecting apparatus in which a lattice-shaped optical fiber bundle is arranged on a rear surface of a sheet-shaped detection medium according to a third embodiment.

FIG. 4 is a diagram showing a plate-shaped radiation detection medium of Example 4 and horizontal and vertical wavelength shift fiber bundles used in a two-dimensional radiation image detection apparatus.

FIG. 5 is a diagram showing a two-dimensional radiation image detection device using the radiation detection medium of FIG. 4 and a shift fiber bundle.

FIG. 6 is a diagram of a two-dimensional radiation detecting apparatus using a gas that is ionized by ionizing radiation and emits light as a radiation detector.

FIG. 7 is a diagram showing a detection unit including a gas ionized and emitted by ionizing radiation, a container for containing the gas, and horizontal and vertical optical fiber bundles arranged in the container.

8 is a diagram illustrating a two-dimensional radiation image detection device using the detection unit of FIG. 7;

FIG. 9 is a diagram showing a two-dimensional radiation image detecting apparatus in which four lights emitted from both ends of an optical fiber bundle are arranged side by side in two or four in parallel.

FIG. 10 is a diagram illustrating a two-dimensional radiation image detecting apparatus that switches and uses three imaging cameras for detecting and storing a Stokes image obtained on a phosphor screen of a Stokes tube.

FIG. 11 is a diagram showing a two-dimensional radiation image detection apparatus using a detection medium formed into a sheet by mixing a neutron converter.

FIG. 12 is a diagram illustrating a conventional two-dimensional radiation image detection device including a photomultiplier tube, an amplifier for amplifying the signal, and the like.

FIG. 13 is a diagram showing a conventional method of inputting all optical signals at two-dimensional positions to a Stokes tube.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G065 AA12 AB01 AB04 AB11 BA04 BA18 BA23 BA34 BB02 BC03 BC07 BC19 BC28 BC33 DA10 DA20 2G088 AA03 EE03 EE21 EE27 FF02 FF09 GG11 GG15 KK01 KK02 KK32 KK32 KK35

Claims (16)

[Claims] 1. A radiation detector in which a luminous body for converting ionizing radiation into light is formed into a sheet or a plate, and an optical fiber bundle arranged in a plane on a rear surface for condensing light emitted by the radiation detector. The present invention relates to a two-dimensional radiation image detecting device comprising a device for detecting light from an optical fiber bundle, and performing signal processing and analysis to produce a two-dimensional image of radiation, and detects light from the optical fiber bundle. A device for signal processing and analysis to measure a two-dimensional radiation image arranges light emitted from both ends of an optical fiber bundle horizontally in parallel or vertically in two stages, and emits light corresponding to the arranged width. Optical system capable of changing the width of the streak tube, a streak tube for detecting light output from the optical system, a control circuit for quickly sweeping the streak tube with time, and imaging for capturing a streak image output to the streak tube A two-dimensional signal processing apparatus that digitizes the video signal of the camera and the image-capturing camera, stores the data as time-series data of the intensity of the emission signal, stores the data, and analyzes and converts it into a two-dimensional radiation image. Radiation image detector. 2. A radiation-sensitive fiber bundle in which radiation-sensitive optical fibers made of a material emitting light by ionizing radiation are arranged in a plane, and a light emitted from the radiation-sensitive fiber bundle is detected and subjected to signal processing. The present invention relates to a two-dimensional radiation image detection device comprising a device for analyzing and forming a two-dimensional radiation image. The two-dimensional radiation image is detected by detecting light from a radiation-sensitive fiber bundle, and performing signal processing and analysis. An optical system that measures the light emitted from both ends of the radiation-sensitive fiber bundle is arranged in parallel horizontally or vertically in two stages, and the width of the light corresponding to the arranged width can be changed. A streak tube for detecting light output from the optical system, a control circuit for quickly sweeping the streak tube with time, an imaging camera for capturing a streak image output to the streak tube, The camera video signals are digitized and
A two-dimensional radiation image detecting device characterized by comprising a signal processing / analyzing device which stores as a time-series data of an emission signal intensity and performs an analyzing process to form a two-dimensional radiation image. 3. The method according to claim 1, wherein both ends of the optical fiber bundle are arranged side by side in parallel or vertically in two stages.
The output light is adjusted by an optical system, the width of which is set to the width of the streak tube as a perceived width, and is incident on the streak tube.
The control circuit sweeps the deflection voltage of the deflection plate of the streak tube at a time interval shorter than the emission life of the radiation detector for a time corresponding to the vertical width of the streak tube, and detects the radiation voltage during the time corresponding to the vertical width. The signal incident on the detector and emitted light is used as the streak image of the streak tube, and the streak image is captured by the imaging camera. The video signal of the imaging camera is digitized by the signal processing / analyzing device, and the emission signal intensity at both ends of the optical fiber bundle is measured. A two-dimensional radiation image that is stored as time-series data and is obtained by analyzing the light emission position based on the peak shape of each light emission signal obtained from the time-series data and obtaining a two-dimensional radiation image. Detection method. 4. The light-emitting signal intensity of light output from both ends of each optical fiber when the video signal of the imaging camera is digitized and stored by a signal processing / analyzing device and then analyzed, according to claim 1-3. Based on the peak shape of each luminescence signal obtained from the time-series data, the difference between the time until the luminescence in the radiation detector reaches each end of each optical fiber and the respective intensity are calculated, and the time difference or luminescence is calculated. A two-dimensional radiation image detection method characterized by performing analysis processing based on an intensity difference or a combination of a time difference and an intensity difference to obtain an incident position of ionizing radiation on a radiation detector and obtain a two-dimensional radiation image. 5. A radiation detector in which a luminous body for converting ionizing radiation into light is formed into a sheet or a plate, and a grid on the rear surface of the radiation detector at intervals corresponding to the positional resolution in the horizontal and vertical directions. Two optical fiber bundles composed of a large number of optical fibers arranged, and light emitted from the optical fiber bundles arranged in the horizontal and vertical directions are detected, signal processed and analyzed, and the radiation 2
The present invention relates to a two-dimensional radiation image detection device including a device for forming a two-dimensional image, and detects light from a bundle of optical fibers arranged in a grid pattern in a horizontal direction and a vertical direction, and performs signal processing and analysis on the radiation. A device for producing a two-dimensional image is arranged in parallel with the light emitted from one end of each of the optical fiber bundles in the horizontal direction and the vertical direction, or by arranging the light in two stages vertically, corresponding to the arranged width. An optical system capable of changing the width of light, a streak tube for detecting light output from the optical system, a control circuit for quickly sweeping the streak tube with time, and an imaging camera for capturing a streak image output to the streak tube And digitize the video signal of the imaging camera and store it as time-series data of the emission signal intensity,
Two-dimensional radiation image detection characterized by comprising a signal processing and analysis device that obtains a two-dimensional radiation image by analyzing the light emission position based on the peak shape of each light emission signal obtained from the time-series data apparatus. 6. A radiation detector in the form of a plate made of a transparent luminous body for converting ionizing radiation into light, and mounted in a grid in the horizontal and vertical directions so as to be in contact with four side surfaces of the radiation detector. An optical system capable of arranging light emitted from one end of two optical fiber bundles composed of a large number of optical fibers horizontally in parallel or arranging vertically in two stages, and changing the width of light corresponding to the arranged width; A streak tube for detecting light output from the optical system, a control circuit for quickly sweeping the streak tube with time, an imaging camera for capturing a streak image output to the streak tube, and digitizing a video signal of the imaging camera,
A two-dimensional radiation image detection apparatus characterized in that the two-dimensional radiation image detection apparatus is characterized in that it is stored as time-series data of the intensity of a light emission signal, and is constituted by a signal processing / analysis apparatus which analyzes this data to produce a two-dimensional radiation image. 7. A radiation detector comprising a gas or liquid which is ionized by ionizing radiation and emits light, a container for enclosing the gas or liquid, and a number of optical fibers mounted in a grid in the horizontal and vertical directions in the container. A two-dimensional radiation image composed of two optical fiber bundles and a device for detecting light emitted from the optical fiber bundles arranged in the horizontal direction and the vertical direction, and performing signal processing and analysis into a two-dimensional image of radiation. This is related to a detection device, and collects light emitted when ionizing radiation is incident and ionizes gas or liquid with bundles of optical fibers in the horizontal and vertical directions, and separates the optical fibers in the horizontal and vertical directions. An optical system in which the light emitted from one end of the bundle is arranged horizontally in parallel or vertically in two stages, and the width of the light corresponding to the arranged width can be changed, and the light output from the optical system A streak tube for detecting light, and a control circuit for sweeping time streak tube at a high speed, an imaging camera for imaging the streak image which is output to the streak tube,
The two-dimensional feature is that the video signal of the imaging camera is digitized and stored as time-series data of the emission signal intensity, and the data is analyzed and processed to form a two-dimensional radiation image. Radiation image detector. 8. A gas or liquid used as a radiation detector which ionizes and emits light by ionizing radiation, a container for enclosing the gas or liquid, a metal wire stretched at a predetermined interval in the container, and A high-voltage power supply for applying voltage, a vertical optical fiber bundle stretched at regular intervals in the container, but with an optical fiber stretched around a metal wire and bundled outside the container, and these optical fibers A horizontal optical fiber bundle stretched at a right angle at regular intervals and bundled outside the container,
The present invention relates to a two-dimensional radiation image detecting device comprising a device for detecting light emitted from both ends of a horizontal and vertical optical fiber bundle, processing and analyzing the signal, and forming a two-dimensional image of radiation. When a high voltage is applied from a high-voltage power supply to a wire stretched in a container and ionizing radiation is incident to ionize gas or liquid, the light that is amplified and emitted is collected by the horizontal and vertical optical fiber bundles. Light, and light emitted from one end of each of the optical fiber bundles in the horizontal direction and the vertical direction are arranged side by side in parallel or arranged in two stages vertically,
An optical system capable of changing the width of light corresponding to the arranged width, a streak tube for detecting light output from the optical system, a control circuit for quickly sweeping the streak tube with time, and output to the streak tube An imaging camera that captures a streak image, and a video signal of the imaging camera that is digitized and stored as time-series data of the emission signal intensity.
A two-dimensional radiation image detection device characterized by comprising an analysis device. 9. The optical system according to claim 5, wherein one end of each of the optical fiber bundles in the horizontal direction and the vertical direction is arranged in parallel in a horizontal direction or in two stages in a vertical direction, and the width of output light is controlled by an optical system. Adjust the width of the streak tube to the perceived width, enter the streak tube, collect the light emitted in response to the incidence of radiation on the radiation detector using an optical fiber, and convert the light signal of the width output from the optical system. The control circuit sweeps the deflection voltage of the deflection plate of the streak tube at a time interval shorter than the emission life of the radiation detector for a time corresponding to the vertical width of the streak tube, and within the radiation detector within a time corresponding to the vertical width. The signal that is incident and emitted is used as a streak image of the streak tube, and the streak image is captured by an imaging camera, and the video signal of the imaging camera is digitized by a signal processing / analyzing device to time-series the emission signal intensity. Stored as data, the time series of the two-dimensional radiation image detecting method featuring that the two-dimensional radiation image determined crest shape of the light-emitting signal obtained by analysis of the emission position on the basis of the data. 10. The image processing apparatus according to claim 5, wherein the video signal of the imaging camera is digitized by a signal processing / analyzing device, stored, and then analyzed, and then output from one end of each of the horizontal and vertical optical fibers. Since the optical fibers are arranged in a lattice based on the time-series data of the light emission signal intensity of the light, the light emitted in one lattice in the radiation detection body moves in the horizontal direction corresponding to the lattice. The two-dimensional radiation image is obtained by obtaining the incident position of ionizing radiation on the radiation detector by utilizing the detection by the two optical fibers and the two vertical optical fibers. Radiation image detection method. 11. The device according to claim 5-11, wherein the light emitted from the two optical fibers in the horizontal direction and the two optical fibers in the vertical direction corresponding to each lattice of the optical fibers arranged in a lattice. Based on the peak shape of each emission signal obtained from the time-series data of the signal intensity, each emission time in the four optical fibers is calculated, and the light emitted in one lattice in the radiation detector is calculated. If detected, each emission time in the four optical fibers matches within a preset time corresponding to the length of the grating. A two-dimensional radiation image detection method characterized by applying a coincidence method to determine a position where light is emitted in a radiation detector, obtain an incident position of ionizing radiation on the radiation detector, and obtain a two-dimensional radiation image. 12. In the structure of the apparatus according to claim 5-8, instead of arranging light emitted from one end of each of the optical fiber bundles in the horizontal direction and the vertical direction in parallel in a horizontal direction or in two stages in a vertical direction. A two-dimensional radiation image detecting apparatus characterized in that four light beams emitted from both ends of an optical fiber bundle are arranged in two or four rows in parallel. 13. The apparatus according to claim 12, wherein when the video signal of the imaging camera is digitized and stored by a signal processing / analyzing device and then analyzed, the output is output from both ends of each of the horizontal and vertical optical fibers. The peak shape of each light emission is analyzed based on the time-series data of the light emission signal intensity of the light, and the time required for the light emission in the radiation detector to reach both ends of each optical fiber in the horizontal and vertical directions. The difference and the respective intensities are obtained, the horizontal and vertical directions are analyzed based on the arrival time difference or the intensity difference, or a combination of the two, and the incident position of ionizing radiation to the radiation detector is obtained to obtain a two-dimensional radiation image. A two-dimensional radiation image detection method characterized in that: 14. An apparatus according to claim 12, wherein the incident position is determined by combining the incident position determining method according to claim 9 and the incident position determining method according to claim 13. Detection method. 15. A two-dimensional radiographic image according to claim 1-14, wherein two or more imaging cameras are used for detection and accumulation of a streak image obtained on the phosphor screen of the streak tube. A two-dimensional radiation image detection device characterized by repeating the detection of the radiation. 16. A neutron converter material for converting neutrons into ionizable radiation in the radiation detector according to claim 1-15, Gd, 6Li, 10B or 3He.
A two-dimensional neutron image detection apparatus characterized in that a two-dimensional neutron image is obtained by using a neutron detector containing at least one kind of, or a mixture of, or a combination of.