JP6781918B2 - Information processing equipment, imaging methods, and imaging programs - Google Patents

Description

The present invention relates to an information processing apparatus, an imaging method, and an imaging program.

There are three main types of radiation: photon beams, electron beams, and particle beams. There are many methods for measuring (imaging) the radioactivity density distribution of a radiation source (photon source) that emits photon rays such as X-rays and gamma rays. The radioactivity density distribution shows the position of the radiation source and the intensity of radiation from the radiation source at the position. Examples of the method for measuring the radioactivity density distribution include those using a physical collimator such as lead and tungsten, those using a quantum collimator based on photon-electron interaction, and those using simultaneous measurement of pair-produced photons. In either method, it is premised that the energy of the target photon beam is known, and the setting is made according to the energy of the photon beam.

An imaging device using a quantum collimator (hereinafter referred to as a quantum collimator type imaging device) measures the energy and the direction of arrival of photon rays at the quantum collimator section and the subsequent detector section. When imaging a gamma ray source, an energy peak corresponding to the gamma ray is formed on the detected energy spectrum. In general, photon rays are prone to scattering. Since the scattered photon rays lose energy during scattering, they are detected on the energy spectrum on the lower energy side than the peak energy. The quantum collimator type imaging device can measure the total energy of the photon beam by performing photoelectric absorption in the post-stage detector section, but the photon beam may also be scattered in the post-stage detector section. Again, the detected energy is lower than the original energy. Therefore, the quantum collimator type imaging device generally detects an event of energy near the peak and does not detect an event of energy lower than the energy near the peak to perform imaging.

Japanese Patent No. 4486623 Japanese Patent No. 4352122 Japanese Patent No. 5244029 JP-A-2015-07524

On the other hand, it is very difficult to image a radiation source (electron beam source) that emits an electron beam (β ray). This is because the electron beam has a very short range in the substance and hardly reaches the detector in the subsequent stage. Therefore, it is conceivable to indirectly image the electron beam source by imaging the generation position of the braking X-ray emitted when the electron beam stops in the substance.

However, when imaging a photon source with continuous energy such as braking X-rays, the incident photon rays do not have a specific energy, so no peak is observed on the observed spectrum, and imaging of the gamma ray source. It is difficult to take the same method as.

An object of the present invention is to image a radiation source of continuous energy.

The following means are adopted to solve the above problems.
That is, the first aspect is
An information processing device that calculates the position of the radiation source by detecting radiation from a substance containing a radiation source with a Compton camera including a scatterer and an absorber.
The first ratio, which is the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, and the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, the radiation scattered by the substance. The second ratio, the third ratio, which is the ratio of the radiation scattered by the absorber of the Compton camera, is calculated, and is incident on the Compton camera based on the first ratio, the second ratio, and the third ratio. For each energy lost by the Compton camera, a fourth ratio is calculated, which is the ratio of the radiation of the energy to the radiation from the radiation source scattered by the scatterer and absorbed by the absorber. Probability calculation unit and
The position of the radiation source is calculated based on the detection result of the radiation incidented on the Compton camera by the Compton camera in which the energy lost by the Compton camera is within a predetermined energy range including the fourth ratio. With the position calculation unit,
An information processing device to be provided.

Aspects of disclosure may be realized by executing the program by an information processing device. That is, the structure of the disclosure can be specified as a program for causing the information processing apparatus to execute the process executed by each means in the above-described embodiment, or as a computer-readable recording medium on which the program is recorded. Further, the structure of the disclosure may be specified by a method in which the information processing apparatus executes the processing executed by each of the above means. The configuration of the disclosure may be specified as a system including an information processing device that performs processing executed by each of the above means.

According to the present invention, it is possible to image a radiation source of continuous energy.

FIG. 1 is a diagram illustrating an operating principle of a Compton camera used in a quantum collimator type imaging device. FIG. 2 is a diagram showing an example of radiation emitted from the human body. FIG. 3 is a diagram showing an example of an energy spectrum of gamma rays emitted from a cobalt 57 radiation source. FIG. 4 is a diagram showing an example of an energy spectrum of beta rays emitted from a yttrium-90 source. FIG. 5 is a diagram showing a system configuration example of the embodiment. FIG. 6 is a diagram showing an example of a functional block of an information processing device of an imaging device. FIG. 7 is a diagram showing an example of a computer hardware configuration. FIG. 8 is a diagram showing an example of an operation flow of position calculation by the information processing device of the imaging device. FIG. 9 is a diagram showing an example of the energy (E ₁ + E ₂ ) dependence of radiation detected by a Compton camera for the percentage of correct events. FIG. 10 is a diagram showing an example of the calculation result of the position of the radiation source. FIG. 11 is a diagram showing the energy dependence of the calculation result of the position of the radiation source.

Hereinafter, embodiments will be described with reference to the drawings. The configuration of the embodiment is an example, and the configuration of the invention is not limited to the specific configuration of the disclosed embodiment. In carrying out the invention, a specific configuration according to the embodiment may be appropriately adopted.

[Embodiment]
(Operating principle of Compton camera)
FIG. 1 is a diagram illustrating an operating principle of a Compton camera used in a quantum collimator type imaging device. The Compton camera of FIG. 1 uses two position-sensitive radiation detectors, a scatterer and an absorber, and indicates the position and energy at which photon rays scatter Compton at the scatterer and the position at which photon absorption is subsequently performed by the absorber. The Compton scattering angle θ (the direction in which the photon rays fly) is calculated by accurately measuring the energy. Compton cameras use this principle to image photon sources. Compton cameras, in principle, do not require a collimator. By using silicon (Si) as the scatterer of the Compton camera and the cadmium telluride (CdTe) semiconductor element as the absorber, it is possible to image a wide energy range with high energy resolution. Scatterers and absorbers of Compton cameras are not limited to these. Scatterers and absorbers are planar and are arranged in parallel.

ここで、ｍ_ｅは電子の静止質量、ｃは真空中の光速、Ｅ_１は散乱体で電子に与えられるエネルギー、Ｅ_２は吸収体で吸収される光子のエネルギーである。Ｅ_１は、光子線が散乱体で失うエネルギーである。Ｅ_１＋Ｅ_２は、コンプトンカメラに入射される放射線がコンプトンカメラで失うエネルギーである。ここで、線源からの放射線がコンプトンカメラに入射され、散乱体で散乱して吸収体で吸収されるとすると、Ｅ_１＋Ｅ_２が線源から放出される放射線のエネルギーである。光子が散乱された位置（第１位置）と、散乱された光子が吸収された位置（第２位置）とが分かれば、光子の飛来方向を第１位置と第２位置とを結ぶ直線を中心線とし、第１位置を頂点とし、中心線と母線とのなす角をθとする円錐の側面内に線源が存在することが分かる。１つの線源から放出される複数の方向の光子を検出することで、線源が存在し得る位置を示す複数の円錐の側面を求めることができる。複数の円錐の側面の重なる位置が線源の位置であると求められる。 The scattering angle θ is obtained as follows.

Here, _me is the rest mass of the electron, c is the speed of light in vacuum, E ₁ is the energy given to the electron by the scatterer, and E ₂ is the energy of the photon absorbed by the absorber. E ₁ is the energy that photon rays lose in the scatterer. E ₁ + E ₂ is the energy that the radiation incident on the Compton camera loses in the Compton camera. Here, assuming that the radiation from the radiation source is incident on the Compton camera, scattered by the scatterer, and absorbed by the absorber, E ₁ + E ₂ is the energy of the radiation emitted from the radiation source. If the position where the photons are scattered (first position) and the position where the scattered photons are absorbed (second position) are known, the direction in which the photons fly is centered on the straight line connecting the first position and the second position. It can be seen that the radiation source exists in the side surface of the cone having the line, the first position as the apex, and the angle formed by the center line and the generatrix as θ. By detecting photons in a plurality of directions emitted from one source, it is possible to determine the side surfaces of a plurality of cones indicating the positions where the source can exist. The position where the sides of the plurality of cones overlap is determined to be the position of the radiation source.

(Radiation emitted from the human body)
FIG. 2 is a diagram showing an example of radiation emitted from the human body. By administering a radiopharmaceutical (β-ray drug) using a beta nuclide that accumulates in a tumor to the human body, the radiopharmaceutical accumulates in the tumor. Radioactive drugs emit β-rays, so if you know the location of β-ray emission, you can know the location of the tumor. In the human body, β-rays emit braking X-rays as they bend and travel. The range of β rays in the body is 11 mm or less. Here, the emission position of the braking X-ray is regarded as the same as the emission position of the β ray. Therefore, to obtain the emission position of the braking X-ray emitted from the human body is to obtain the emission position of β-ray, and to obtain the position of the tumor. Beta rays have a very short range inside the human body and are difficult to detect outside the human body. On the other hand, braking X-rays can be detected even outside the human body. Therefore, in the imaging device of the present embodiment, the position of the tumor in the human body can be obtained by arranging the Compton camera outside the human body and obtaining the emission position of the braking X-ray. The imaging device of the present embodiment is not limited to the tumor in the human body, and can determine the position of the radiation source in the substance.

In the imaging of the photon source using a quantum collimator, the energy of the incident photon beam is assumed to be the sum of the measured values of the quantum collimator (scatterer) and the measured values of the subsequent detector (absorber). In this case, if Compton scattering occurs instead of photoelectric absorption in the subsequent detector, the energy of the incident photon rays will be underestimated. The measurement event also includes photons scattered somewhere after the generation of braking X-rays and before they enter the Compton camera. This is a photon due to an event (fake event) at a position different from the position of the source of the braking X-ray.

In the case of a photon beam with continuous energy such as braking X-rays, the energy of the incident photon is not determined, so the measured energy of the regular event (photon from the source of braking X-ray) and the above fake event Difficult to distinguish. Therefore, it is difficult to perform the same method as the method of imaging a photon radiation source having a specific energy such as gamma rays. Therefore, here, by limiting the energy region used for imaging, the ratio of the fake event is minimized, and highly accurate imaging is performed.

FIG. 3 is a diagram showing an example of an energy spectrum such as gamma rays emitted from a cobalt 57 radiation source in a substance. The horizontal axis of the graph in FIG. 3 is energy, and the vertical axis is the number of detected events. Cobalt 57 undergoes γ decay and emits 122 keV gamma rays. In the example of FIG. 3, there is a gamma ray peak at 122 keV. Here, in the above Compton camera, by setting E ₁ + E ₂ to 122 keV, the position of the radiation source can be accurately obtained by performing imaging.

FIG. 4 is a diagram showing an example of an energy spectrum such as beta rays emitted from a yttrium-90 source in a substance. The horizontal axis of the graph of FIG. 4 is energy, and the vertical axis is the number of detected events. Yttrium-90 undergoes β-decay and emits 2.28 MeV beta rays. In the example of FIG. 4, there is no beta ray peak. This is because beta rays stop in matter. Here, braking X-rays are emitted as the beta rays progress. Braking X-ray energy is lower than beta ray energy. Also, the radiation at which braking X-rays are scattered in matter is lower than the energy of beta rays. The direction of radiation from which the braking X-rays are scattered in the material is often different from the direction of the beta source. Therefore, when determining the direction of the beta radiation source, the radiation from which the braking X-rays are scattered in the substance becomes noise. Noise reduction is required to accurately calculate the direction of beta radiation sources using braking X-rays.

(Configuration example)
FIG. 5 is a diagram showing a system configuration example of the present embodiment. The system 10 of this embodiment includes an imaging device 100 and a substance 200 including a radiation source. The imaging device 100 includes a Compton camera 110 and an information processing device 120. The substance 200 is arranged in the vicinity of the Compton camera 110. It is assumed that the substance 200 includes a radiation source to be positioned. The Compton camera 110 may be made movable in the vicinity of the substance 200 and may detect radiation from a plurality of positions. The information processing device 120 processes the signal acquired by the Compton camera 110. The substance 200 is, for example, a human body to which a radiopharmaceutical using a beta nuclide accumulating in a tumor has been administered. Here, it is assumed that the substance 200 emits beta rays, and the beta rays emit braking X-rays while bending in the substance 200.

Compton camera 110 includes scatterers and absorbers, as shown in FIG. Each time the radiation is incident, the Compton camera 110 detects the position and energy of the radiation incident on the scatterer (energy given to the electrons) and the position and energy of the radiation incident on the absorber (absorbed energy). To do. The Compton camera 110 outputs the detected result to the information processing device 120. As the Compton camera 110, a well-known Compton camera can be used.

FIG. 6 is a diagram showing an example of a functional block of an information processing device of an imaging device. The information processing device 120 includes an acquisition unit 121, a probability calculation unit 122, a position calculation unit 123, and a storage unit 124.

The acquisition unit 121 acquires the position and energy of the incident radiation in the scatterer and the position and energy in the absorber from the Compton camera 110. The acquisition unit 121 stores the acquired information in the storage unit 124.

The probability calculation unit 122 calculates the ratio of the radiation scattered before the incident and the ratio of the radiation scattered by the absorber of the Compton camera 110 for each energy in the range of the energy of the radiation that can be emitted from the substance 200. The probability calculation unit 122 stores the calculation result in the storage unit 124.

The position calculation unit 123 calculates the position of the radiation source based on the information acquired by the acquisition unit 121 and the calculation result calculated by the probability calculation unit 122.

The storage unit 124 stores information and the like used in the information processing device 120.

FIG. 7 is a diagram showing an example of a computer hardware configuration. The computer 90 shown in FIG. 7 has a general computer configuration. The information processing device 120 is realized by using a computer 90 as shown in FIG. 7. The computer 90 of FIG. 7 includes a processor 91, a memory 92, a storage unit 93, an input unit 94, an output unit 95, and a communication control unit 96. These are connected to each other by a bus. The memory 92 and the storage unit 93 are computer-readable recording media. The hardware configuration of the computer is not limited to the example shown in FIG. 7, and components may be omitted, replaced, or added as appropriate.

The computer 90 loads the program stored in the recording medium into the work area of the memory 92 and executes the program, and the computer 90 controls each component or the like through the execution of the program to perform a function suitable for a predetermined purpose. It can be realized.

The processor 91 is, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor).

The memory 92 includes, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory). The memory 92 is also called a main storage device.

The storage unit 93 is, for example, an EPROM (Erasable Programmable ROM) or a hard disk drive (HDD, Hard Disk Drive). Further, the storage unit 93 can include a removable medium, that is, a portable recording medium. The removable medium is, for example, a USB (Universal Serial Bus) memory or a disc recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). The storage unit 93 is also called a secondary storage device.

The storage unit 93 stores various programs, various data, and various tables in a readable and writable recording medium. The storage unit 93 stores an operating system (OS), various programs, various tables, and the like. The information stored in the storage unit 93 may be stored in the memory 92. Further, the information stored in the memory 92 may be stored in the storage unit 93.

The operating system is software that mediates between software and hardware, manages memory space, manages files, manages processes and tasks, and so on. The operating system includes a communication interface. The communication interface is a program that exchanges data with other external devices and the like connected via the communication control unit 96. External devices and the like include, for example, other computers, external storage devices, and the like.

The input unit 94 includes a keyboard, a pointing device, a wireless remote controller, a touch panel, and the like. Further, the input unit 94 can include a video or image input device such as a camera, or an audio input device such as a microphone.

The output unit 95 includes a display device such as an LCD (Liquid Crystal Display), an EL (Electroluminescence) panel, a CRT (Cathode Ray Tube) display, a PDP (Plasma Display Panel), and an output device such as a printer. Further, the output unit 95 can include an audio output device such as a speaker.

The communication control unit 96 connects to another device and controls communication between the computer 90 and the other device. The communication control unit 96 is, for example, a LAN (Local Area Network) interface board, a wireless communication circuit for wireless communication, and a communication circuit for wired communication. The LAN interface board and wireless communication circuit are connected to a network such as the Internet.

A computer that realizes the information processing device 120 functions as an acquisition unit 121, a probability calculation unit 122, and a position calculation unit 123 by loading a program stored in the auxiliary storage device into the main storage device and executing the program. To realize. On the other hand, the storage unit 124 is provided in the storage area of the main storage device or the auxiliary storage device.

The series of processes in the information processing apparatus 120 can be executed by hardware or software.

The steps of writing a program include not only processes performed in chronological order in the order described, but also processes executed in parallel or individually, although not necessarily processed in chronological order. Some steps in writing the program may be omitted.

(Operation example)
FIG. 8 is a diagram showing an example of an operation flow of position calculation by the information processing device of the imaging device.

In S101, the probability calculation unit 122 of the information processing apparatus 120 estimates the amount of the substance existing between the radiation source of the substance 200 and the Compton camera 110, and the braking X generated by the beta ray from the β radiation source in the substance 200. Calculate the ratio of photon rays (directly incident photons) that are incident on the Compton camera 110 without scattering and the ratio of photon rays (scattered photons) that are scattered at any position and incident on the Compton camera 110. To do. The probability calculation unit 122 can calculate the ratio of directly incident photons and the ratio of scattered photons by, for example, X-ray CT (Computed Tomography) data and Monte Carlo simulation with respect to the substance 200. In general, the proportion of scattered photons is higher on the low energy side. The direction of arrival of directly incident photons is considered to be the direction of the beta source.

Next, the probability calculation unit 122 estimates the rate at which scattering occurs in the absorber of the Compton camera 110. The rate at which scattering occurs in the absorber of the Compton camera 110 depends on the energy of the photons incident on the absorber. The rate at which scattering occurs in the absorber is higher on the high energy side. The probability calculation unit 122 estimates the rate at which scattering occurs in the absorber for each energy incident on the absorber.

Further, the probability calculation unit 122 determines that the directly incident photons are scattered by the scatterer and are scattered by the absorber (without being scattered) from the ratio of the directly incident photons, the ratio of the scattered photons, and the ratio of scattering in the absorber. Calculate the percentage of absorbed radiation. An event in which a directly incident photon is scattered by a scatterer and absorbed by an absorber (without being scattered) by a Compton camera is called a correct event. In the case of the correct event, the energy E ₀ of the directly incident photon is the sum of the energy E ₁ given to the electron by the scatterer and the energy E ₂ absorbed by the absorber (E ₀ = E ₁ + E ₂ ).

FIG. 9 is a diagram showing an example of the energy (E ₁ + E ₂ ) dependence of radiation detected by a Compton camera for the percentage of correct events. In the graph of FIG. 9, the horizontal axis represents the radiation energy (E ₁ + E ₂ ) detected by the Compton camera, and the vertical axis represents the percentage of correct events. In the example of FIG. 9, the percentage of correct events is highest near 250 keV. That is, when the imaging device 100 determines the direction of the beta ray source using the data in the vicinity of 250 keV, the accuracy of the position of the beta ray source is improved. The energy with the highest percentage of correct events depends on the beta source, the type and size of the substance 200, the distance to the substance 200, and the like.

In S102, the acquisition unit 121 acquires the position and energy of radiation incident on the scatterer and the position and energy of radiation incident on the absorber detected by the Compton camera 110 from the Compton camera 110. Radiation (photon rays) is incident on the Compton camera 110 from the substance 200. The acquisition unit 121 stores the acquired information in the storage unit 124.

In S103, the position calculation unit 123 determines the range of radiation energy to be acquired based on the calculation result of the probability calculation unit 122. The position calculation unit 123 determines as the energy range of the radiation to acquire the range including the energy having the highest ratio of correct events. The width of the energy range may be determined by the amount of radiation acquired by the Compton camera 110. For example, when the amount of radiation acquired by the Compton camera 110 is small (for example, when the measurement time is short), the range of energy is increased. This is because if the amount of radiation is small, the accuracy of the position of the beta radiation source may decrease. Further, for example, when the amount of radiation acquired by the Compton camera 110 is large, the range of energy is reduced. By reducing the energy width, the percentage of correct events can be increased and the accuracy of the beta radiation source position can be improved. Here, for example, assuming that the percentage of correct events is as shown in FIG. 9, the energy range is determined to be 200 keV to 300 keV.

The position calculation unit 123 extracts from the storage unit 124 that the radiation energy (E ₁ + E ₂ ) detected by the Compton camera 110 is included in the determined energy range. The position calculation unit 123 obtains the side surface of the cone indicating the radiation source for each of the extracted radiations. The more the side of the cone passes, the more likely it is the location of the radiation source.

FIG. 10 is a diagram showing an example of the calculation result of the position of the radiation source. FIG. 10 shows the calculation result of the position of the radiation source on the plane at a predetermined distance from the Compton camera 110. In the example of FIG. 10, it is shown that the side surface of the cone passes more toward the center of the figure (the darker the color). That is, in the example of FIG. 10, it is shown that the closer to the center, the higher the possibility of the position of the radiation source, and the closer to the periphery, the lower the possibility of the position of the radiation source. Is shown. As a result, the imaging device 100 can determine the position of the radiation source. Assuming that the distance from the Compton camera 110 to the radiation source is the predetermined distance, it is considered that the position of the radiation source is near the center of FIG. The position calculation unit 123 counts the number of passes through the side surface of the cone at each point in the three-dimensional space, and the point through which the most passes may be the position of the radiation source. Actually, the radiation source exists at a position corresponding to the vicinity of the center of the figure of FIG.

FIG. 11 is a diagram showing the energy dependence of the calculation result of the position of the radiation source. FIG. 11 shows the calculation result of the position of the radiation source on the plane at a predetermined distance from the Compton camera 110. In the example of FIG. 11, when the range of energy determined by the position calculation unit 123 is assumed to be 100-140 keV, 140-200 keV, 200-300 keV, 300-400 keV, 400-500 keV, 500-700 keV, 700-1300 keV. The calculation result of the position of the radiation source of is shown. The calculation result of 200-300 keV is the same as the example of FIG. In the example of FIG. 11, as in the example of FIG. 10, the darker the color, the more the side surfaces of the cone pass through. In the example of 200-300 keV, the part that is likely to be the position of the radiation source is small, but as the energy range becomes smaller from the range of 200-300 keV, it is more likely to be the position of the radiation source. The part is getting bigger. Also, as the energy range increases from the 200-300 keV range, the areas that are likely to be the location of the radiation source are mottled. That is, the farther away from the range of 200-300 keV, the lower the accuracy of the position of the radiation source. Therefore, for example, when the imaging apparatus 100 calculates using the entire energy range, the accuracy of the calculated radiation source position is reduced.

(Action and effect of the embodiment)
It has been difficult to accurately visualize a photon source with continuous energy by the conventional imaging method of "using the event of the peak part according to the energy of the generated photon". According to the imaging device 100, it is possible to calculate the position of a photon radiation source having continuous energy such as braking X-rays.

In a physical collimator type imaging device, it is necessary to use a collimator that matches the energy of the photon beam, and it is difficult to calculate the position of the photon source having continuous energy. The quantum collimator type imaging device 100 of the present embodiment can perform imaging using photon rays having a wide range of energies. If the optimum energy range can be set by the imaging apparatus 100, the position of the radiation source can be calculated with higher accuracy.

The imaging apparatus 100 calculates the ratio of directly incident photons, the ratio of scattered photons, and the ratio of scattering at the absorber. From these ratios, the imaging device 100 determines the ratio of events (correct events) in which directly incident photons are scattered by the scatterer and absorbed by the absorber, and the energy of radiation (E ₁ + E) detected by the Compton camera 110. ₂ ) Calculate for each. The radiation energy detected by the Compton camera 110 is the energy that the incident radiation loses in the Compton camera 110.

For example, in the human body, yttrium-90 labeled zevalin, a beta nuclide, has been used to treat malignant lymphoma. However, since it is difficult to image pure β-emission nuclides, zevalin labeled with iodine-111, which is a gamma nuclide, is administered in advance to measure the pharmacokinetics in a pseudo manner. However, this method is time-consuming and costly, and there is concern about differences in dynamics due to differences in labeled nuclides. If the imaging device 110 enables imaging of the yttrium-90-labeled drug as it is, it will be possible to accurately grasp the pharmacokinetics while reducing cost reduction.

The configuration of the above embodiment can be implemented by combining these as much as possible.

<Computer readable recording medium>
A program that enables a computer or other machine or device (hereinafter, computer or the like) to realize any of the above functions can be recorded on a recording medium that can be read by the computer or the like. Then, by causing a computer or the like to read and execute the program of this recording medium, the function can be provided.

Here, a recording medium that can be read by a computer or the like is a recording medium that can be read from a computer or the like by accumulating information such as data or programs by electrical, magnetic, optical, mechanical, or chemical action. To say. In such a recording medium, elements constituting a computer such as a CPU and a memory may be provided, and the CPU may execute a program.

Further, among such recording media, those that can be removed from a computer or the like include, for example, a flexible disk, a magneto-optical disk, a CD-ROM, a CD-R / W, a DVD, a DAT, an 8 mm tape, a memory card, and the like.

In addition, there are hard disks, ROMs, and the like as recording media fixed to computers and the like.

10 System 100 Imaging device 110 Compton camera 120 Information processing device 121 Acquisition unit 122 Probability calculation unit 123 Position calculation unit 124 Storage unit

Claims (3)

An information processing device that calculates the position of the radiation source by detecting radiation from a substance containing a radiation source with a Compton camera including a scatterer and an absorber.
The first ratio, which is the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, and the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, the radiation scattered by the substance. The second ratio, the third ratio, which is the ratio of the radiation scattered by the absorber of the Compton camera, is calculated, and is incident on the Compton camera based on the first ratio, the second ratio, and the third ratio. For each energy lost by the Compton camera, a probability calculation unit that calculates a fourth ratio of the radiation of the energy to the radiation scattered by the scatterer and absorbed by the absorber, and
The position of the radiation source is determined based on the detection result of the radiation by the Compton camera, in which the radiation incident on the Compton camera having the highest fourth ratio is within a predetermined energy range including the energy lost by the Compton camera. The position calculation unit to be calculated
Provided,
The radiation from the radiation source is braking X-rays by beta rays emitted from the radiation source.
Information processing device. An imaging method in which radiation from a substance containing a radiation source is detected by a Compton camera including a scatterer and an absorber to calculate the position of the radiation source.
The computer
The first ratio, which is the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, and the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, the radiation scattered by the substance. The second ratio, the third ratio, which is the ratio of the radiation scattered by the absorber of the Compton camera, is calculated, and is incident on the Compton camera based on the first ratio, the second ratio, and the third ratio. each energy radiation loses in the Compton camera, calculates a fourth fraction radiation from the radiation source to the radiation of the energy is the percentage of radiation absorbed by the absorber is scattered by the scatterer ,
The position of the radiation source is determined based on the detection result of the radiation by the Compton camera, in which the radiation incident on the Compton camera having the highest fourth ratio is within a predetermined energy range including the energy lost by the Compton camera. calculate,
It ’s an imaging method that does things
The radiation from the radiation source is braking X-rays by beta rays emitted from the radiation source.
Imaging method. An imaging program that calculates the position of the radiation source by detecting radiation from a substance containing a radiation source with a Compton camera containing a scatterer and an absorber.
The computer
The first ratio, which is the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, and the ratio of the radiation from the radiation source to the radiation incident on the Compton camera, the radiation scattered by the substance. The second ratio, the third ratio, which is the ratio of the radiation scattered by the absorber of the Compton camera, is calculated, and is incident on the Compton camera based on the first ratio, the second ratio, and the third ratio. each energy radiation loses in the Compton camera, calculates a fourth fraction radiation from the radiation source to the radiation of the energy is the percentage of radiation absorbed by the absorber is scattered by the scatterer ,
The position of the radiation source is determined based on the detection result of the radiation by the Compton camera, in which the radiation incident on the Compton camera having the highest fourth ratio is within a predetermined energy range including the energy lost by the Compton camera. calculate,
An imaging program to do that,
The radiation from the radiation source is braking X-rays by beta rays emitted from the radiation source.
Imaging program.

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