JP2014020947A - Radiation measuring device and radiation measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce statistical errors (relative errors) without increasing the size of a radiation detector or extending a radiation measurement time period.SOLUTION: In a radiation measuring device 1, a data retrieval unit 23 retrieves, from a database 30 in which previous measurement data of spatial radiation are stored in association with location information, location information matched with a current location, detected by a locating unit 9, within a predetermined allowable range to obtain previous measurement data corresponding to the retrieved location information. When spatial radiation dose rates of the previous measurement data obtained from the database 30 is, within a predetermined allowable range, matched with spatial radiation dose rates of current measurement data obtained by a radiation detector 6, on the basis of both the previous measurement data obtained from the database 30 and the current measurement data, a dose rate calculation unit 22 calculates spatial radiation dose rates and statistical errors thereof.

Description

  The present invention relates to a radiation measuring apparatus and a radiation measuring method.

  Radiation measurement devices, for example photodiode-type measurement devices used in personal dosimeters, convert the signal output when radiation passes through the light-receiving surface of the detector into a pulse signal and detect it during a predetermined measurement time It is a mechanism to count the pulse signal that is. Usually, the radiation dose rate (unit: μSv / h) and its statistical relative error (value indicating ±% error from the measured value) are displayed on the display unit of the radiation measuring apparatus.

  The radiation dose rate is obtained by multiplying a count rate value (unit: cpm (count per minute)) that is a count value per unit time by a conversion coefficient. The conversion coefficient is a value obtained using a standard radiation source for each detector. The reciprocal of the conversion coefficient is equal to the radiation detection sensitivity (unit: cpm / (μSv / h)). Statistical relative error is calculated by the reciprocal of the square root of all counts. The relative error decreases as the measurement time increases or the count rate value increases.

  Conventionally, a technique has been proposed in which the count rate value is increased by increasing the sensitivity of the radiation detector, thereby improving the measurement accuracy of radiation. For example, Japanese Patent Application Laid-Open No. 2001-208551 (Patent Document 1) discloses a scintillation type radiation detector in which a liquid crystal panel is arranged along the main surface of a scintillator plate having a large area. When scintillation light enters the liquid crystal, an electromotive force is generated due to the photoelectric effect of the liquid crystal. The incident position of the radiation is detected based on the position of the liquid crystal cell whose output voltage has changed.

  The radiation detector disclosed in Japanese Patent Laying-Open No. 2005-249483 (Patent Document 2) is configured by stacking a plurality of substrates on which photodiode type radiation detection elements are formed. The cathode electrodes and anode electrodes of the plurality of radiation detection elements are electrically connected to each other.

JP 2001-208551 A Japanese Patent Laid-Open No. 2005-249483

  Like the radiation detector described in the above-mentioned patent document, if the area of the radiation receiving surface is increased or a plurality of radiation detection elements are mounted, there arises a problem that the size of the radiation detector increases. . Furthermore, the price of the radiation detector becomes high. If the measurement time is lengthened in order to reduce the statistical error (relative error), the measurement cannot be easily performed, and the usability of the radiation measuring apparatus is deteriorated.

  The present invention has been made in consideration of the above-mentioned problems, and its purpose is to reduce statistical errors (relative errors) without increasing the size of the radiation detector or increasing the radiation measurement time. To provide a radiation measurement apparatus and a radiation measurement method that can be reduced.

  A radiation measurement apparatus according to one aspect of the present invention includes a radiation detector that detects spatial radiation, a positioning unit that detects a position, a data search unit, and a dose rate calculation unit. The data retrieval unit retrieves position information that matches the current position detected by the positioning unit within a predetermined allowable range from a database that stores the past spatial radiation measurement data in association with the position information. Acquire past measurement data corresponding to the information. The dose rate calculation unit determines whether the spatial radiation dose rate based on the past measurement data acquired from the database matches the spatial radiation dose rate based on the current measurement data obtained by the radiation detector within a predetermined allowable range. The spatial radiation dose rate and its statistical error are calculated based on both the past measurement data and the current measurement data acquired from the above.

  Preferably, the radiation measuring apparatus further includes a communication device connectable with a network. The above database is stored in network storage. The current measurement data measured by the radiation detector and the current position information detected by the positioning unit are stored in this database.

  Alternatively, preferably, the radiation measurement apparatus further includes a storage device that stores the database. The current measurement data measured by the radiation detector and the current position information detected by the positioning unit are stored in this database.

  Alternatively, preferably, the radiation measurement apparatus further includes a communication device connectable to the Internet. The database is stored in a web server that provides a website on the Internet.

  Preferably, the database stores the past spatial radiation measurement data in association with the measurement date and time. The data search unit searches the database for position information that matches the current position detected by the positioning unit within a predetermined allowable range, and corresponds to the searched position information and is measured within a predetermined period from the present time. Obtain past measurement data.

  In another aspect, the present invention is a radiation measurement method, a step of measuring current spatial radiation, a step of detecting a current position, and a database that stores past spatial radiation measurement data in association with position information From the step of searching for position information that matches the detected current position within a predetermined allowable range, acquiring past measurement data corresponding to the searched position information, and the past measurement data acquired from the database Based on both past measurement data and current measurement data obtained from the above database when the spatial radiation dose rate and the spatial radiation dose rate based on the current measurement data match within a predetermined tolerance, Calculating a radiation dose rate and its statistical error.

  According to the present invention, the statistical error (relative error) of the detected radiation dose rate can be reduced without increasing the size of the radiation detector or increasing the radiation measurement time.

2 is a block diagram illustrating an example of a hardware configuration of the radiation measuring apparatus according to Embodiment 1. FIG. It is a block diagram which shows the functional structure of the part regarding the radiation measurement of the radiation measuring device of FIG. 3 is a flowchart showing a radiation measurement procedure according to the first embodiment. 6 is a block diagram illustrating an example of a hardware configuration of a radiation measurement apparatus according to Embodiment 2. FIG. It is a block diagram which shows the functional structure of the part regarding the radiation measurement of the radiation measuring device of FIG. 6 is a flowchart showing a radiation measurement procedure according to the second embodiment. It is a block diagram which shows the functional structure of the part regarding the radiation measurement of the radiation measuring device by Embodiment 3. FIG. 10 is a flowchart showing a radiation measurement procedure according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

<Embodiment 1>
[Hardware configuration of radiation measurement equipment]
FIG. 1 is a block diagram illustrating an example of a hardware configuration of the radiation measuring apparatus according to the first embodiment. A radiation measurement apparatus 1 includes a central processing unit (CPU) 2, a random access memory (RAM) 3, a read only memory (ROM) 4, a nonvolatile memory 5, a radiation detector 6, a display unit 8, and an input unit. 7, a GPS receiver 9 and a GPS antenna 10 are included.

  The CPU 2 controls the overall operation of the radiation measuring apparatus 1 by executing programs stored in the ROM 4 and the nonvolatile memory 5. The RAM 3 and ROM 4 are used as the main memory of the CPU 2.

  The nonvolatile memory 5 is configured by, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) such as a flash memory. A hard disk may be provided in place of the nonvolatile memory. The nonvolatile memory 5 stores data output from the CPU 2. In particular, in the case of Embodiment 1, the non-volatile memory 5 stores a database storing past spatial radiation measurement data.

  The radiation detector 6 outputs a pulse signal when detecting radiation. For example, the radiation detector 6 includes a silicon PIN photodiode to which a bias voltage is applied in the reverse direction, an amplifier, and a comparator. In a silicon PIN photodiode, a pulsed current signal is generated by electron-hole pairs generated when radiation passes through a depletion layer. The amplifier converts the current pulse output from the silicon PIN photodiode into a voltage pulse and amplifies it. The comparator compares the output voltage of the amplifier with a reference voltage and becomes a high level when the output voltage of the amplifier is equal to or higher than the reference voltage and becomes a low level when the output voltage of the amplifier is lower than the reference voltage (ie, shaping). Output pulse signal).

  The display unit 8 is configured by a liquid crystal display panel, an organic EL (Electro Luminescence) panel, or the like, and displays character information or the like (for example, a radiation measurement result) based on a command from the CPU 2.

  The input unit 7 includes a hardware key for the user to input a command such as start of radiation measurement to the radiation measurement apparatus 1. The input unit 7 may be configured to include a touch panel integrated with the display unit 8. In this case, the user performs an input operation via the touch panel.

  The GPS receiver (positioning unit) 9 includes a radio frequency integrated circuit (RFIC) and a baseband IC. The RFIC generates a baseband signal by down-converting signals from four or more GPS satellites received via the antenna 10 and A / D (Analog-to-Digital) converts the generated baseband signal. Output. The baseband IC calculates its current location based on the baseband signal output from the RFIC. Instead of providing the baseband IC, the CPU 2 may perform signal processing performed by the baseband IC according to a program.

  In the case of an apparatus configuration in which a mobile phone is provided with a radiation detector, the position of the own device can be detected without using GPS radio waves. For example, an area (cell) of a radio base station with which a mobile phone is currently communicating can be set as the current location. Alternatively, it is possible to measure the time until radio waves arrive at the own device from three or more radio base stations and detect the current location of the own device based on the distance corresponding to the arrival time of the radio waves.

[About radiation measurement]
The feature of the radiation measurement method according to Embodiment 1 is that the measurement accuracy can be improved even in a short measurement time by using data measured in the past at the same place in addition to the current measurement data of spatial radiation.

  For example, using a radiation measurement apparatus that requires a measurement time of 1 minute in order to perform measurement with sufficient accuracy, measurement is performed for 30 seconds, the measurement result for 30 seconds is stored, and the measurement is temporarily interrupted. Then, after a while, measurement is started again and measurement is performed for 30 seconds. If the radiation dose rates [μSv / h] of these two measurements are equal to each other within a predetermined allowable range, it is assumed that there is no sudden dose change between the first and second measurements. The radiation dose rate and statistical error are calculated using both measurement results. In this case, since the first measurement is taken over and the second measurement is performed, a measurement result with the same accuracy as that obtained when the measurement is continuously performed for one minute is obtained.

  Next, a method for calculating the radiation dose rate and its statistical error in the case where both current and past radiation data are used as described above will be described. Below, the calculation method when only the current radiation measurement data is used as a premise will be described first.

Generally, when the total count N is detected during the measurement time t by radioactive decay, the total count N and the count per unit time (count rate) n = N / t are known to follow a Poisson distribution. For relatively large radioactivity, the Poisson distribution can approximate a Gaussian distribution. In this case, the standard deviation (absolute error) σ1 of the total count N is equal to the square root of the total count N (hereinafter referred to as “sqrt (N)”), and the standard deviation (absolute error) σ2 of the count rate n is n / Equal to the square root of t (sqrt (n / t)). Therefore, the relative error E, ie, σ1 / N and σ2 / n is
E = σ1 / N = σ2 / n = 1 / sqrt (N) (1)
It is expressed as These absolute and relative errors are called statistical errors.

  The radiation dose rate [μSv / h] is obtained by multiplying the count rate value [cpm] by the conversion coefficient. The conversion coefficient is obtained for each radiation detector using a standard radiation source, and is a reciprocal of the sensitivity of the radiation detector.

Specifically, when the conversion coefficient of the radiation detector 6 of the radiation measuring apparatus 1 is Ma, the detected count rate value is Ca [cpm], and the measurement time is Ta [minutes], the radiation dose rate Sa [μSv / h]
Sa = Ma × Ca (2)
It is expressed as The relative error Ea [%] is
Ea = (1 / (sqrt (Ta × Ca)) × 100 (3)
It is expressed as

  The relative error [%] mentioned here is a value indicating ±±% of error with respect to the measured value. For example, when measurement is performed for 1 minute using a radiation detector having a conversion coefficient of 0.05 and the count rate value is 25 cpm, the radiation dose rate is 1.25 μSv / h from the calculation formula (2). From (3), the relative error is ± 20%. This is because if this radiation detector is used for many measurements for 1 minute, 68.27% of the total number of measurements is 1.25 μSv / h ± 20%, that is, 1.00 μSv / h. It means that it is included in the range of ˜1.50 μSv / h.

  Next, a method for calculating a radiation dose rate and its statistical error using current radiation measurement data and past radiation measurement data at the same location will be described.

  It is assumed that there are n (n ≧ 1) past radiation measurement data measured at almost the same location as the current location and having a radiation dose rate approximately equal to the current dose rate. The count rate values of these past radiation measurement data are Cb (1) to Cb (n) [cpm], and the radiation measurement times are Tb (1) to Tb (n) [minutes], respectively. Since the first embodiment shows the case where radiation measurement is performed using the same radiation detector, it is assumed that the conversion coefficient corresponding to n past radiation data does not change with Ma.

In this case, the radiation dose rate S based on the current and past radiation measurement data includes the radiation dose rate Sa based on the current radiation measurement data and the radiation dose rates Sb (1) to Sb (n) based on the past n measurement data. Is equal to the arithmetic mean of That is, the radiation dose rate S is
S = (Sa + Sb (1) + ... + Sb (n)) / (n + 1) (4)
= Ma x (Ca + Cb (1) + ... + Cb (n)) / (n + 1) ... (5)
It is expressed as

The relative error E [%] based on the current and past radiation measurement data is obtained by adding the total count value Na currently detected by the radiation detector 6 and the total count values Nb (1) to Nb (n) detected in the past. Equal to the reciprocal of the square root of the value. That is, the relative error E [%] is
E = (1 / sqrt (Na + Nb (1) +... + Nb (n))) × 100 (6)
= (1 / sqrt (Ta × Ca + Tb (1) × Cb (1) +... + Tb (n) × Cb (n))) × 100 (7)
It is expressed as

[Functional configuration of radiation measurement equipment]
Hereinafter, the radiation measurement function of the radiation measurement apparatus 1 of FIG. 1 will be specifically described.

  FIG. 2 is a block diagram showing a functional configuration of a part related to radiation measurement of the radiation measurement apparatus of FIG. With reference to FIG. 2, the CPU 2 of the radiation measurement apparatus 1 has functions as a measurement control unit 21, a dose rate calculation unit 22, and a data search unit 23. These functions are realized by the CPU 2 executing a program for radiation measurement.

  When the user inputs a radiation measurement start command to the input unit 7 in FIG. 1, the measurement control unit 21 measures the spatial radiation over a predetermined measurement time by the radiation detector 6, and further, the GPS receiver 9 Get location information. After the radiation measurement is completed, the measurement control unit 21 transmits the radiation measurement data including the count rate value, the measurement time, the conversion coefficient, and the like together with the measurement date and time information and the position information obtained by the GPS receiver 9 to the nonvolatile memory 5. It stores in the radiation database 30 inside.

  The radiation database 30 stores radiation data (count rate value, measurement time, conversion coefficient, etc.) measured so far by the radiation measurement apparatus 1 in association with measurement position information and measurement date information. . The data search unit 23 searches the radiation database 30 for position information that matches the current position detected by the GPS receiver 9 within a predetermined allowable range, and acquires past radiation measurement data corresponding to the searched position information. To do. In this case, a search condition that measurement is performed within a predetermined time from the present time may be further added.

  Subsequently, the data search unit 23 determines that the spatial radiation dose rate based on the past radiation measurement data acquired from the radiation database 30 and the spatial radiation dose rate based on the current radiation measurement data obtained by the radiation detector are within a predetermined allowable range. To determine whether they match. The space radiation dose rate [μSv / h] is obtained by multiplying the count rate value [cpm] by the conversion coefficient. As a result, when both coincide, the dose rate calculation unit 22 calculates the above-described formulas (5) and (7) based on both the past radiation measurement data and the current radiation measurement data acquired from the radiation database. To calculate the spatial radiation dose rate and its statistical error. The calculated space radiation dose rate and its statistical error are displayed on the display unit 8.

[Measurement procedure of spatial radiation]
FIG. 3 is a flowchart showing a radiation measurement procedure according to the first embodiment. Hereinafter, with reference to FIG. 1 to FIG. 3, a procedure for measuring spatial radiation using both measurement data measured in the past by the radiation measurement apparatus 1 and measurement data measured this time using the same radiation measurement apparatus 1. This will be specifically described.

1. Location information measurement:
When the user operates the input unit of the radiation measurement apparatus 1 and inputs a radiation measurement start command, the CPU 2 (measurement control unit 21) of the radiation measurement apparatus 1 can first acquire the GPS receiver 9 (or current location information). The current location information is acquired by other means) (step S1).

2. Spatial radiation measurement:
Next, the CPU 2 (measurement control unit 21) starts measurement of spatial radiation by the radiation detector 6 (step S2), and ends measurement of spatial radiation when a predetermined measurement time has elapsed (step S3). The measurement time is generally determined in advance for each model of the radiation measuring apparatus based on the allowable statistical error (relative error) and the sensitivity of the radiation detector 6 [cpm / (μSv / h)]. However, the measurement may be terminated at an arbitrary timing designated by the user.

3. Saving measurement results:
After the measurement of the spatial radiation, the CPU 2 (measurement control unit 21) transmits the measurement data including the conversion coefficient, the position information, the measurement date and time, the measurement time, and the count rate value of the radiation detector 6 to the radiation in the nonvolatile memory 5. Save in the database 30 (step S4). It is assumed that measurement data measured in the past at the same place is already stored in the radiation database 30.

4). Search for past radiation measurement data:
Next, the CPU 2 (data search unit 23) searches for measurement data having the same position information from past measurement data stored in the radiation database 30 in the nonvolatile memory 5 (step S5). In this case, the position information may match if it is within a predetermined allowable range in consideration of position detection accuracy.

5. Comparison of radiation dose rates:
When past radiation data measured in the same place is found (YES in step S6), the CPU 2 (data search unit 23) determines the radiation dose rate [μSv / h] based on the past radiation measurement data found by the search. Is compared with the radiation dose rate [μSv / h] obtained by this measurement (step S7). Since the radiation dose rate [μSv / h] is represented by the product of the conversion coefficient and the count rate value [cpm] as in the above-described calculation formula (2), the conversion coefficient and the count rate value included in the measurement data Can be obtained using.

6). Calculation of radiation dose rate and statistical error:
If the past radiation dose rate and the current radiation dose rate are equal (YES in step S8), the CPU 2 (dose rate calculation unit 22) determines that the past radiation measurement data can be used, and the past radiation measurement data and this time The radiation dose rate and the statistical error (relative error) are calculated from the measured data (step S9). Specifically, the CPU 2 (dose rate calculation unit 22) calculates the radiation dose rate and the statistical error (relative error) according to the above-described calculation formulas (5) and (7).

  If the criteria for determining that the past radiation dose rate is equal to the current radiation dose rate are too strict, the number of cases where there is no past radiation measurement data that can be used increases. Therefore, the determination criteria may be widened so that they are determined to be equal within a predetermined allowable range (for example, within ± X (%) with respect to the current radiation dose rate). .

  When the past radiation dose rate and the current radiation dose rate are different from each other beyond a predetermined allowable range (NO in step S8), the CPU 2 (dose rate calculation unit 22) has changed the dose rate at that location. The radiation dose rate and the statistical error (relative error) are calculated from the current measurement data without using the past radiation measurement data (step S10). Specifically, the CPU 2 (dose rate calculation unit 22) calculates a radiation dose rate and a statistical error (relative error) according to the above-described calculation formulas (2) and (3).

7). Display of measurement results:
After completing the calculation of the radiation dose rate [μSv / h] and the statistical error (relative error) [%], the CPU 2 (dose rate calculation unit 22) displays the calculation result on the display unit (step S11).

[Effect of Embodiment 1]
For example, if the measurement time included in the past radiation measurement data is 25 minutes and the count rate value is 1 cpm, the statistical error in this case is 20% from the calculation formula (3). If the measurement time included in the current measurement data is 25 minutes and the count rate value is 1 cpm, the statistical error in this case is also 20%. On the other hand, when both the past radiation measurement data and the current measurement data are used according to the calculation formula (7), the statistical error is reduced to about 14%.

  As described above, according to the radiation measuring apparatus of the first embodiment, radiation data measured in the past is stored in the memory of the main body, and this stored data is used to perform statistical errors (relative errors) during radiation measurement. ) And the measurement accuracy can be increased. Furthermore, since it is possible to measure from the continuation of past data measured for a short time (several minutes), radiation measurement can be performed easily, and data with a short measurement time can be used effectively. it can.

<Embodiment 2>
In the second embodiment, the radiation database 30 for storing measurement data is stored in the network storage 31 instead of the main body memory (nonvolatile memory 5). The network storage is a file server that can read and write data via a network, and is accessible from a plurality of terminals. Therefore, the measurement data can be written in the radiation database 30 not only by the device itself but also by other radiation measurement devices. Data written in the radiation database 30 is shared by a plurality of radiation measurement apparatuses. Hereinafter, a specific description will be given with reference to FIGS.

[Configuration of radiation measurement equipment]
FIG. 4 is a block diagram illustrating an example of a hardware configuration of the radiation measuring apparatus according to the second embodiment. The radiation measurement apparatus 101 in FIG. 4 is different from the radiation measurement apparatus 1 in FIG. 1 in that it further includes a communication device 11 that can be connected to a network. In the case of FIG. 4, a case where wireless communication is performed via the antenna 12 is shown, and a wireless LAN (Local Area Network) communication device or a mobile phone communication device is an example. Although different from the case of FIG. 4, the communication device 11 for wired LAN may be used. The network storage 31 may be provided on a wireless LAN or a wired LAN, or may be provided on the Internet connected via a wireless LAN, a wired LAN, or a mobile phone network.

  Since the other points of FIG. 4 are the same as those of FIG. 1, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 5 is a block diagram showing a functional configuration of a part related to radiation measurement of the radiation measuring apparatus of FIG. It is assumed that the network storage 31 is accessible from any of the radiation measurement apparatuses 101A, 101B, 101C,. Hereinafter, the radiation measurement apparatus 101A will be described as a representative.

  With reference to FIG. 5, the CPU 2 of the radiation measurement apparatus 101 </ b> A has functions as a measurement control unit 21, a dose rate calculation unit 22, and a data search unit 23. These functions are realized by the CPU 2 executing a program for radiation measurement.

  When the user inputs a radiation measurement start command to the input unit 7 in FIG. 4, the measurement control unit 21 causes the radiation detector 6 to detect spatial radiation over a predetermined measurement time, and further, the GPS receiver 9 Get location information. After the radiation measurement is completed, the measurement control unit 21 transmits the radiation measurement data including the count rate value, the measurement time, and the conversion coefficient together with the measurement date and time information and the position information obtained by the GPS receiver 9 to the communication device 11. And stored in the radiation database 30 in the network storage 31.

  The data search unit 23 accesses the network storage 31 via the communication device 11, and from the radiation database 30 in the network storage 31, position information that matches the current position detected by the GPS receiver 9 within a predetermined allowable range. And the past radiation measurement data corresponding to the searched position information is acquired. In this case, a search condition that measurement is performed within a predetermined time from the present time may be further added.

  Subsequently, the data search unit 23 determines that the spatial radiation dose rate based on the past radiation measurement data acquired from the radiation database 30 and the spatial radiation dose rate based on the current radiation measurement data obtained by the radiation detector are within a predetermined allowable range. To determine whether they match. As a result, when they match, the dose rate calculation unit 22 determines the spatial radiation dose rate [μSv / h] and its statistics based on both the past radiation measurement data and the current radiation measurement data acquired from the radiation database. Calculate the error (statistical error).

  Here, it is assumed that there are n (n ≧ 1) past radiation measurement data measured at substantially the same location as the current location and having a radiation dose rate substantially equal to the current dose rate. In the case of the second embodiment, these n pieces of data are not limited to those measured by the same radiation measuring apparatus. The count rate values of these past radiation measurement data are Cb (1) to Cb (n) [cpm], the radiation measurement times are Tb (1) to Tb (n) [minutes], respectively, and the radiation dose rate [μSv / H] are conversion coefficients Mb (1) to Mb (n). The count rate value of the current radiation measurement data measured by the radiation measurement apparatus 101A is Ca [cpm], the radiation measurement time is Ta [minutes], and the conversion coefficient is Ma.

In this case, the radiation dose rate S based on the current and past radiation measurement data is obtained by rewriting the above formula (5).
S = (Ma × Ca + Mb (1) × Cb (1) +... + Mb (n) × Cb (n)) / (n + 1) (8)
Given in. The relative error E [%] based on the current and past radiation measurement data is given by the aforementioned equations (6) and (7). The calculated space radiation dose rate and its statistical error are displayed on the display unit 8.

[Measurement procedure of spatial radiation]
FIG. 6 is a flowchart showing a radiation measurement procedure according to the second embodiment. The flowchart of FIG. 6 differs from the flowchart of FIG. 3 in that steps S4A and S5A are executed instead of steps S4 and S5.

  That is, in FIG. 6, after the measurement of spatial radiation, the CPU 2 (measurement control unit 21) transmits measurement data including the conversion coefficient, position information, measurement date and time, measurement time, and count rate value of the radiation detector 6 to the network. It saves in the radiation database 30 in the storage 31 (step S4A). Next, the CPU 2 (data search unit 23) searches for measurement data having the same position information from past radiation measurement data stored in the radiation database 30 in the network storage 31 (step S5A). In this case, the position information may match if it is within a predetermined allowable range in consideration of position detection accuracy.

  Since the other steps in FIG. 6 are the same as those in FIG. 3, the same or corresponding steps are denoted by the same reference numerals and description thereof will not be repeated.

[Effect of Embodiment 2]
As described above, according to the radiation measuring apparatus of the second embodiment, the radiation data of the own apparatus and other apparatuses measured in the past are stored in the network storage, and by using the data stored in the network storage, Statistical errors (relative errors) can be reduced during radiation measurement, and measurement accuracy can be increased.

<Embodiment 3>
On the Internet, there is a website where people who have measured the radiation dose rate can post measurement results consisting of the measured value of the radiation dose rate, measurement location, measurement date, measurement device name, etc. Can be seen by anyone on the Internet. For example, there are websites such as “Radiation dose maps made by everyone” (http://minnade-map.net/) and “Measure and Geiger!” (Http://hakatte.jp/).

  In the third embodiment, a method will be described in which measurement errors at the time of radiation measurement are reduced and measurement accuracy is increased by using measurement results obtained from such a website.

[Configuration of radiation measurement equipment]
FIG. 7 is a block diagram showing a functional configuration of a part related to radiation measurement of the radiation measuring apparatus according to the third embodiment. The hardware configuration of the radiation measuring apparatus 102 according to the third embodiment is the same as that in FIG. However, in the case of Embodiment 3, the communication device 11 can be connected to the Internet.

  With reference to FIG. 7, the CPU 2 of the radiation measuring apparatus 102 has functions as a measurement control unit 21, a dose rate calculation unit 22, and a data search unit 23. These functions are realized by the CPU 2 executing a program for radiation measurement.

  When the user inputs a radiation measurement start command to the input unit 7 in FIG. 4, the measurement control unit 21 causes the radiation detector 6 to detect spatial radiation over a predetermined measurement time, and further, the GPS receiver 9 Get location information. After the radiation measurement is completed, the measurement control unit 21 transmits the radiation measurement data including the count rate value, the measurement time, the conversion coefficient, and the like together with the measurement date and time information and the position information obtained by the GPS receiver 9 to the nonvolatile of the main body. Stored in the measurement data storage area 51 in the memory 5.

  The data search unit 23 accesses the web server 32 that provides a website (posting site for measurement data of the spatial radiation dose rate) on the Internet via the communication device 11. The web server 32 stores a radiation database 30 that stores data including a measurement value of a spatial radiation dose rate, a measurement location, a measurement date and time, a measurement device name, and the like. The data search unit 23 searches the radiation database 30 for position information that matches the current position detected by the GPS receiver 9 within a predetermined allowable range, and obtains past radiation measurement data corresponding to the searched position information. get. In this case, a search condition that measurement is performed within a predetermined time from the present time may be further added.

  Subsequently, the data search unit 23 determines that the spatial radiation dose rate based on the past radiation measurement data acquired from the radiation database 30 and the spatial radiation dose rate based on the current radiation measurement data obtained by the radiation detector are within a predetermined allowable range. To determine whether they match. As a result, when the two values match, the dose rate calculation unit 22 calculates the spatial radiation dose rate [μSv / h] and its radiation rate based on both the past radiation measurement data and the current radiation measurement data acquired from the radiation database 30. Statistical error (statistical error) is calculated according to the above-described calculation formulas (4) and (7). The calculated space radiation dose rate and its statistical error are displayed on the display unit 8.

  Here, in order to calculate the relative error E [%] according to the equation (7), information on the measurement time and information on the count rate value are required. For this purpose, a measuring instrument database 52 for storing information related to the measuring apparatus is prepared in advance. The measuring instrument database 52 stores a measuring device name, a conversion coefficient, and a standard measuring time. The measuring instrument database 52 may be on the memory (nonvolatile memory 5) of the radiation measuring apparatus 102 main body, or may be in a storage on the network. The dose rate calculation unit 22 acquires the conversion coefficient and the standard measurement time of the measuring device from the measuring device database 52 using the name of the measuring device acquired from the radiation database 30 as a search key. In this case, the count rate value can be calculated by dividing the radiation dose rate by the conversion factor.

  If the past radiation data provided by the website contains information on statistical error (relative error) “%”, the relative error E [ Specifically, the radiation dose rate based on the current radiation measurement data is Sa [μSv / h], the statistical error is Ea [%], and the total count is Na. , The radiation dose rate is Sb (1) to Sb (n) [μSv / h], and the corresponding statistical error (relative error) is Eb (1), respectively. ) To Eb (n) [%], and the total count values are Nb (1) to Nb (n), respectively.

In this case, the radiation dose rate S based on the current and past radiation measurement data can be calculated according to the above-described equation (4). In order to calculate the relative error E [%] based on the current and past radiation measurement data, first, the total count value Na, Nb (i) (1 ≦ i ≦ n) and the relative errors Ea, Eb (i) Relational expression:
Na = (100 / Ea) ² (9)
Nb (i) = (100 / Eb (i)) ² (10)
Are used to calculate total count values Na and Nb (1) to Nb (n) from relative errors Ea and Eb (1) to Eb (n), respectively. Next, the relative error E [%] is calculated by using the above-described calculation formula (6).

[Measurement procedure of spatial radiation]
FIG. 8 is a flowchart showing a radiation measurement procedure according to the third embodiment. In the flowchart of FIG. 8, step S5B is executed instead of step S5, step S61 is executed between steps S6 and S7, and steps S81 and S82 are executed between steps S8 and S9. This is different from the flowchart of FIG. In the following, different steps will be mainly described in detail, and the same or corresponding steps may be denoted by the same reference symbols, and description thereof may not be repeated.

1. Location information measurement:
7 and 8, when the user operates the input unit of the radiation measurement apparatus 1 and inputs a radiation measurement start command, the CPU 2 (measurement control unit 21) of the radiation measurement apparatus 1 starts with a GPS receiver. 9 is used to obtain information on the current location (step S1).

2. Spatial radiation measurement:
Next, the CPU 2 (measurement control unit 21) starts measurement of spatial radiation by the radiation detector 6 (step S2), and ends measurement of spatial radiation when a predetermined measurement time has elapsed (step S3).

3. Saving measurement results:
After the measurement is completed, the CPU 2 (measurement control unit 21) stores measurement data including the conversion coefficient, position information, measurement date and time, measurement time, and count rate value of the radiation detector 6 in the measurement data storage area in the nonvolatile memory 5. Save to 51.

4). Search for past radiation measurement data:
Next, the CPU 2 (data search unit 23) accesses the radiation dose rate posting site via the communication device 11, and searches for measurement data having the same position information from the past radiation measurement data posted. (Step S5B).

5. Comparison of radiation dose rates:
When past radiation data measured at the same place is found (YES in step S6), the CPU 2 (data search unit 23) acquires the radiation dose rate [μSv / h] data and the information of the measuring device name. (Step S61). Next, the CPU 2 (data search unit 23) compares the radiation dose rate [μSv / h] based on the past radiation measurement data found by the search with the radiation dose rate [μSv / h] obtained by this measurement. (Step S7).

6). Search the instrument database:
If the past radiation dose rate and the current radiation dose rate are equal to each other within a predetermined allowable range (YES in step S8), CPU 2 (dose rate calculation unit 22) determines that past radiation measurement data can be used, and the web Using the name of the measuring device acquired from the site as a search key, the conversion coefficient of the measuring device and the standard measurement time are acquired (step S81).

7). Calculation of radiation dose rate and statistical error:
Next, the CPU 2 (dose rate calculation unit 22) calculates the radiation dose rate and the statistical error (relative error) from the past radiation measurement data and the current measurement data according to the above-described calculation formulas (4) and (7). (Step S9).

  When the past radiation dose rate and the current radiation dose rate are different from each other beyond a predetermined allowable range (NO in step S8), or when the conversion coefficient or the like cannot be obtained from the measuring instrument database 52 (NO in step S82). ), The CPU 2 (dose rate calculation unit 22) does not use the past radiation measurement data, and calculates the radiation dose rate and the statistical error (relative error) from the current measurement data according to the above-described calculation formulas (2) and (3). Calculate (step S10).

8). Display of measurement results:
After completing the calculation of the radiation dose rate [μSv / h] and the statistical error (relative error) [%], the CPU 2 (dose rate calculation unit 22) displays the calculation result on the display unit (step S11).

[Effect of Embodiment 3]
As described above, according to the radiation measurement apparatus of the third embodiment, by obtaining and using radiation data measured in the past from a website, the statistical error (relative error) at the time of radiation measurement is reduced, Measurement accuracy can be increased.

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1, 101, 102 Radiation measurement device, 2 CPU, 3 RAM, 4 ROM, 5 Non-volatile memory, 6 Radiation detector, 7 Input unit, 8 Display unit, 9 GPS receiver (positioning unit), 10, 12 Antenna, DESCRIPTION OF SYMBOLS 11 Communication apparatus, 21 Measurement control part, 22 Dose rate calculation part, 23 Data search part, 30 Radiation database, 31 Network storage, 32 Web server, 51 Measurement data storage area, 52 Measuring instrument database.

Claims (6)

A radiation detector for detecting spatial radiation;
A positioning unit for detecting the position;
From the database that stores the past spatial radiation measurement data in association with the position information, the position information that matches the current position detected by the positioning unit within a predetermined allowable range is searched, and the position information corresponding to the searched position information A data search unit for acquiring past measurement data;
Obtained from the database when the spatial radiation dose rate based on the past measurement data obtained from the database and the spatial radiation dose rate based on the current measurement data obtained by the radiation detector match within a predetermined allowable range. A radiation measurement apparatus comprising a dose rate calculation unit that calculates a spatial radiation dose rate and a statistical error thereof based on both past measurement data and current measurement data. A communication device that can be connected to a network;
The database is stored in network storage,
The radiation measurement apparatus according to claim 1, wherein current measurement data measured by the radiation detector and current position information detected by the positioning unit are stored in the database. A storage device for storing the database;
The radiation measurement apparatus according to claim 1, wherein current measurement data measured by the radiation detector and current position information detected by the positioning unit are stored in the database. A communication device that can be connected to the Internet;
The radiation measurement apparatus according to claim 1, wherein the database is stored in a web server that provides a website on the Internet. The database further stores past spatial radiation measurement data in association with measurement date and time,
The data search unit searches the database for position information that matches the current position detected by the positioning unit within a predetermined allowable range, and corresponds to the searched position information and measures within a predetermined period from the present time. The radiation measurement apparatus according to claim 1, wherein the acquired past measurement data is acquired. Measuring the current spatial radiation;
Detecting the current position;
From the database that stores past spatial radiation measurement data in association with the position information, search for position information that matches the detected current position within a predetermined allowable range, and past measurement data corresponding to the searched position information Step to get the
When the spatial radiation dose rate based on the past measurement data acquired from the database and the spatial radiation dose rate based on the current measurement data match within a predetermined allowable range, the past measurement data acquired from the database and the current measurement And a step of calculating a spatial radiation dose rate and a statistical error thereof based on both of the data and the radiation measurement method.

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