JP2003194948A - Radiation measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation measuring apparatus which can obtain a stable output without sacrificing a response speed with reference to a request for the miniaturization of a radiation detector as a radiation detection means. <P>SOLUTION: When the radiation measuring apparatus 10 is provided with an output stabilization means 14, it can obtain a quick response when the detection efficiency of an incident radiation is high, it can obtain a slow response with reference to a radiation whose detection efficiency is low, and it can obtain the stable output with reference to the request for the miniaturization of the radiation detector 11 as the radiation detection means and without sacrificing the response speed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring apparatus, and more particularly to a radiation measuring apparatus for stabilizing the output of radiation dose equivalent.

[0002]

2. Description of the Related Art A conventional radiation measuring apparatus 1 is constructed as shown in FIG. The radiation measuring apparatus 1 and calculation of the radiation dose equivalent using the radiation measuring apparatus 1 will be described.

Conventionally, the radiation measuring apparatus 1 has a radiation detecting means for detecting the radiation, a detection energy calculating means for calculating the energy of the detected radiation, and a weighting operation from the detected radiation energy to calculate the incident radiation. An incident energy calculating means for calculating energy and an integrating means for integrating incident energy for a predetermined time are provided.

When the radiation dose equivalent is calculated using the radiation measuring apparatus 1, the dose equivalent of the radiation is calculated by performing weighting calculation according to the energy of the incident radiation. The radiation incident on the radiation measuring apparatus 1 is detected by a radiation detector 2 as a radiation detecting means, and an electric signal corresponding to the detected radiation is output. The output electric signal is amplified, wave height analyzed, and wave height discriminated by the preamplifier 3 and the wave height analyzer 4 as the detected energy calculating means. The weighted calculator 5 as incident energy calculating means performs weighting calculation on the electric signal subjected to the wave height discrimination according to the wave height, that is, the energy. The incident energy is calculated by this weighting calculation. The weighted electric signals are integrated by the integrator 6 as an integrating means for a predetermined time and output from the radiation measuring apparatus 1.

The energy of the radiation detected by the radiation detector 2 does not always match the energy of the incident radiation. This is because the radiation detector 2 cannot always detect 100% of the energy of the incident radiation. The probability of detecting radiation energy with respect to the energy of incident radiation (hereinafter referred to as detection efficiency) varies depending on the energy level. Therefore, when calculating the incident radiation energy, a weighting calculation is required according to the energy detected by the radiation detector 2, that is, according to the detection efficiency.

Further, the radiation detection efficiency decreases as the radiation energy increases. This is because the material transmittance of radiation increases as the energy of radiation increases. Therefore, as the range of radiation energy that can be detected by the radiation measuring apparatus 1 is increased, the volume of the radiation detector 2, in particular, the length of the radiation sensor of the radiation detector 2 in the radiation incident direction is required. In other words,
The larger the volume of the radiation detector 2, the more stable the output for radiation having high energy.

[0007]

However, as shown in FIG.
In the radiation measuring apparatus 1 shown in Fig. 2, due to the demand for downsizing and compacting of the apparatus, when the volume of the radiation detector 2 is small, that is, when the radiation sensor is short in the radiation incident direction, the radiation energy to be measured is Even within the range, it becomes difficult to detect all the radiation. For example, the detection efficiency of the radiation detector 2 is about 100% at the lowest energy but 1% at the highest energy in the radiation energy range to be measured.
It can be a degree.

The weighting calculation for calculating the energy of the incident radiation takes into consideration the detection efficiency according to the detected energy. Therefore, as described above, in the radiation energy range to be measured, when the radiation detector 2 has a detection efficiency of about 100% at the lowest energy and about 1% at the highest energy, the weighting of the radiation on the highest energy side is performed. ,
The weighting of the radiation on the lowest energy side is increased by several orders of magnitude. Therefore, when the radiation on the highest energy side is incident, the output of the radiation measuring device 1 becomes unstable.

The output of the radiation measuring apparatus 1 can be stabilized by increasing the integration time in the integrator 6, but if the integration time is increased, the response speed will be impaired. As described above, there is a trade-off relationship between the output stabilization and the response speed of the radiation measuring apparatus 1.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a radiation measuring apparatus capable of obtaining a stable output without sacrificing the downsizing request and response speed of the radiation detector. And

[0011]

In order to solve the above-mentioned problems, a radiation measuring apparatus according to the present invention has a radiation detecting means for detecting radiation and an energy of the detected radiation as described in claim 1. A detection energy calculation means, an incident energy calculation means for performing a weighted calculation on the detection result of the detected radiation energy, and calculating the energy of the incident radiation, and an integrating means for integrating the incident energy for a predetermined time. The radiation measuring apparatus provided is characterized by including an output stabilizing means for stabilizing the output of the radiation measuring apparatus.

In order to solve the above-mentioned problems, in the radiation measuring apparatus according to the present invention, as described in claim 2, the output stabilizing means has a time constant according to the detection efficiency of incident radiation. , And a first filter circuit that outputs a constant filter output.

Such a radiation measuring device can obtain a stable output without impairing the response speed.

In order to solve the above-mentioned problems, a radiation measuring apparatus according to the present invention has the following features.
The output stabilizing means has a second filter circuit which has a time constant according to the detection efficiency of incident radiation and outputs the filter output as a function of the elapsed time from the incidence of radiation. To do.

Such a radiation measuring apparatus can satisfy a complicated response request by outputting the output as a function of the elapsed time suitable for the response request.

Further, in order to solve the above-mentioned problems,
In the radiation measuring apparatus according to the present invention, as described in claim 4, the output stabilizing means has a time constant according to the detection efficiency of the incident radiation, and the process after the radiation enters the filter output. A second filter circuit for outputting as a function of time is provided, and the second filter circuit is formed by at least one of an analog filter circuit and a digital filter circuit.

Such a radiation measuring apparatus can easily realize a filter having a time constant corresponding to the detection efficiency by providing a plurality of analog filters having a time constant corresponding to the radiation detection efficiency of the incident energy. Further, by providing a digital filter according to the radiation detection efficiency of the incident energy, it is possible to realize a filter having a time constant according to the detection efficiency, and it is possible to easily change the filter.

On the other hand, in order to solve the above-mentioned problems, the radiation measuring apparatus according to the present invention has the following features.
The output stabilizing means includes a third filter circuit formed by connecting a plurality of the first filter circuits, which are configured by filters having different time constants, in parallel, and a radiation intensity monitor for monitoring a change in radiation intensity. Means and a filter circuit selecting means for selecting an appropriate first filter circuit according to a change in radiation intensity.

Such a radiation measuring apparatus cannot be realized with a single filter circuit even when the radiation field changes, by selecting an appropriate filter circuit from the filter circuit group by the filter circuit selecting means. A stable output can be realized.

In order to solve the above-mentioned problems, the radiation measuring apparatus according to the present invention has the following features.
The output stabilizing means includes a third filter circuit formed by connecting a plurality of the first filter circuits, which are configured by filters having different time constants, in parallel, and a radiation intensity monitor for monitoring a change in radiation intensity. Means and a filter circuit weighting operation means for weighting and outputting the output of the third filter circuit according to the change of the radiation field.

In such a radiation measuring apparatus, the outputs of the filter groups having different time constants are weighted and output according to the change of the radiation field, so that a stable output cannot be realized by a single filter. Output can be realized.

Furthermore, in order to solve the above-mentioned problems, in the radiation measuring apparatus according to the present invention, as described in claim 7, the radiation intensity monitoring means uses the relation between the incident radiation intensity and the count rate. It is characterized in that the change in the counting rate is monitored and the change in the radiation intensity is calculated.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a radiation measuring apparatus according to the present invention will be described below with reference to the accompanying drawings.

[First Embodiment] A first embodiment of the radiation measuring apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 shows a radiation measuring apparatus 10 according to the present invention.
It is a schematic configuration diagram showing a first embodiment of. The radiation measuring apparatus 10 measures the radiation equivalent to the incident radiation when the dose equivalent of the radiation is measured.
The radiation energy detected by the detection energy calculation means 12 is calculated. The energy of the incident radiation is calculated by the incident energy calculating means 13 from the calculation result of the detected energy of the radiation. The calculation result of the energy of the incident radiation is input to the integrator 15 as the integrating means via the output stabilizing means 14. The integrator 15 integrates the incident radiation energy for a predetermined time to calculate the dose equivalent of the incident radiation. The output of the radiation measuring device 10 is stably output without impairing the response speed by passing the output stabilizing means 14 between the incident energy calculating means 13 and the integrator 15 as the integrating means.

Each part of the radiation measuring apparatus 10 will be specifically described.

The radiation detector 11 has a radiation sensor such as cadmium telluride (CdTe) and cadmium zinc telluride (CZT). The radiation incident on the radiation detector 11 is detected by the radiation sensor,
It is converted into an electric signal corresponding to the energy of the detected radiation.

The detected energy calculating means 12 calculates the energy of the radiation input to the radiation measuring apparatus 10 by obtaining the wave height of the input electric signal. The energy calculating means 12 includes a preamplifier 17 and a wave height analyzer 18. The input electric signal is amplified by the preamplifier 17, and the wave height analyzer 18 performs wave height analysis and wave height discrimination of the electric signal.

The incident energy calculating means 13 performs weighting calculation according to the wave height of the electric signal, that is, the energy of the detected radiation to calculate the incident radiation. The weighting calculation is performed by the weighting calculator 19 provided in the incident energy calculating means 13.

The weighting calculation of the weighting calculator 19 will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the detection efficiency and the weighting coefficient with respect to the incident energy of radiation.

Incident energies E1, E2, E3 (E1 <E
When the radiation of 2 <E3) is incident, the relationship between the incident energy and the detection efficiency ef is such that it decreases as the energy increases, as shown in FIG. Therefore, the incident energy of radiation and the weighting coefficient G for dose equivalent calculation
As for the relationship with (E), as shown in FIG. 2 (B), the weighting coefficient increases as the detection efficiency decreases. Here, G
The weighting calculation is performed as (E3) <G (E2) <G (E1).

The output stabilizing means 14 shown in FIG. 1 includes a first filter circuit 21. The first filter circuit 21 has at least one, for example, three, which has a time constant corresponding to the detection efficiency of incident radiation, more specifically, a time constant that increases as the detection efficiency decreases. It has filters 22, 23, 24 and these filters 2
2, 23, 24 are connected in parallel. Also, these filters 22, 23, 24 have different time constants,
It has time constants of τ1, τ2, and τ3. Output stabilizing means 1
Reference numeral 4 selects one filter having an appropriate time constant among the three filters based on the calculation result of the incident energy calculated by the incident energy calculation means 13.

In the first filter circuit 21, the time constants τ1, τ2, τ3 of the filters 22, 23, 24 are set, for example, in inverse proportion to the respective detection efficiencies. For example, the radiation detection efficiencies for the incident radiation energies E1, E2, E3 are ef1, ef2, ef, respectively.
3 and the selected filters are the filter 22, the filter 23, and the filter 24. At this time, the time constants τ1, τ2, τ3 of the filters 22, 23, 24 are formed to be inversely proportional to the respective detection efficiencies ef1, ef2, ef3. That is, the filters 22, 23, 24
The time constants τ1, τ2, τ3 of are detection efficiencies ef1, ef2,
ef3,

## EQU1 ## τ1 × ef1 = τ2 × ef2 = τ3 × ef3 Are formed to have a relationship of

On the other hand, the output characteristics of the filters 22, 23 and 24 included in the first filter circuit 21 will be described with reference to FIG.

FIG. 3 is a diagram showing the relationship between the filter output and the elapsed time after the radiation is incident on the radiation measuring apparatus 10. According to FIG. 3, the filter output is set to a constant value G (E) /. Tau. (0.ltoreq.t.ltoreq..tau.), Where G (E) is the weighting coefficient when the radiation of incident energy E is incident.
That is, the filter outputs of the filters 22, 23, and 24 with respect to the incident energies E1, E2, and E3 of the radiation are G (E1) / τ1, G (E2) / τ2, G (E3), respectively.
/ Τ3.

The integrator 15 integrates the radiation incident energy output from the output stabilizing means 14 for a predetermined time, and thereafter,
It is output as the output of the radiation measuring apparatus 10.

The radiation measuring apparatus 10 has a high detection efficiency when the dose equivalent is calculated by the output stabilizing means 14 including the first filter circuit 21 having the filters 22, 23 and 24 having time constants corresponding to the detection efficiency. A fast response to radiation and a slow response to radiation with low detection efficiency are obtained, and the stable output state can be maintained without impairing the response speed.

According to the first embodiment, the radiation measuring device 1
As the output stabilizing means 14 for stabilizing the output of 0, filters 22, 23, 24 having different time constants according to the detection efficiency are provided.
By including the first filter circuit 21 connected in parallel with each other, a fast response to radiation having high detection efficiency and a slow response to radiation having low detection efficiency can be obtained at the time of dose equivalent calculation. Therefore, a stable output can be obtained without impairing the response speed of the radiation measuring apparatus 10.

[Second Embodiment] A second embodiment of the radiation measuring apparatus according to the present invention will be described with reference to FIGS.

FIG. 4 shows a schematic diagram of the configuration of the radiation measuring apparatus 10A showing this embodiment. The radiation measuring apparatus 10A shown in FIG. 4 includes a second filter circuit 26 in the output stabilizing unit 14A. This radiation measuring device 10A is
Since the radiation stabilizing apparatus 14A is the same as the radiation measuring apparatus 10 shown in FIG. 1 except that the second stabilizing circuit 14A is provided, the same components as those of the radiation measuring apparatus 10 are designated by the same reference numerals. The description is omitted.

The radiation measuring apparatus 10A shown in FIG.
When calculating the radiation dose equivalent, the radiation detector 11, the detected energy calculating means 12, the incident energy calculating means 13, the output stabilizing means 14A, and the integrator are used as in the radiation measuring apparatus 10 shown in FIG. The dose equivalent is output via 15.

The output stabilizing means 14A is set as the second filter circuit 26 so that the filter output is represented by a function of the elapsed time from the incidence of radiation (hereinafter referred to as a filter output function). It has filters 27, 28 and 29, and these filters 27, 28 and 29 are connected in parallel.

FIG. 5 shows the relationship between the filter output of the filter 27 of the second filter circuit 26 and the elapsed time from the incidence of radiation. According to FIG. 5, the filter output function of the filter 27 is, for example, (G (E1) / τ1) ×
It is represented by e ^{−t / τ1} (0 ≦ t), and the time constant τ1 of the filter 27 is set to a magnitude inversely proportional to the detection efficiency ef1 like the filter 22. The filter 27 set in this way can satisfy a more complicated response request without impairing the response speed. Incidentally, the filters 28, 29
Also in the same manner as in the filter 27, the filter output function and the time constant are set.

The filter output is represented by a function of the elapsed time from the incidence of radiation, and the filters 27, 28 and 29 are formed so that the time constant of the filter is inversely proportional to the detection efficiency.
A specific example of the second filter circuit 26 having at least one of an analog filter and a digital filter in the second filter circuit 26 having is described with reference to FIGS. 6 and 7.

FIG. 6 shows RC filters 27A and 28 in the second filter circuit 26 of the radiation measuring apparatus 10A.
A schematic configuration diagram of a second filter circuit (hereinafter referred to as an analog filter circuit) 26A to which A and 29A are applied is shown.
The RC filter 27A is a circuit having at least one resistor (R) and at least one capacitor (C). For example, the RC filter 27A shown in FIG. 6 has one resistor (R1). ) And one capacitor (C1). In this case, the time constant τ1 of the RC filter 27A is the resistance value R1 (Ω: ohm) and the capacitor C.
Since it is a product of the charge capacity value C1 (F: farad) of 1, that is, R1C1, the time constant τ1 of the filter can be easily set according to the detection efficiency. Therefore, the analog filter circuit 26A including the RC filters 27A, 28A, and 29A has time constants τ1 and τ of the filters according to the detection efficiency.
2 and τ3 can be easily set.

On the other hand, FIG. 7 shows the digital filter 2 in the second filter circuit 26 of the radiation measuring apparatus 10A.
A schematic configuration diagram of a second filter circuit (hereinafter, referred to as a digital filter circuit) 26B to which 7B, 28B and 29B are applied is shown. Digital filters 27B, 28B, 2
9B, by setting each filter parameter,
The filter output function can be set freely. Therefore, not only the setting of the filter but also the change of the filter can be facilitated.

According to the second embodiment, the radiation measuring device 1
As the output stabilizing means 14A for stabilizing the output of 0A,
The filter output is expressed as a function of the elapsed time from the incidence of radiation, and for example, a second filter circuit 26 having filters 27, 28, 29 formed so that the time constant of the filter is inversely proportional to the detection efficiency is provided. With the provision, it is possible to satisfy a more complicated response request without impairing the response speed when calculating the dose equivalent. The filter output function is not limited to the above. If the final value of the filter output, that is, the value obtained by integrating the filter function up to the elapsed time is the same as the filter output, another exponential function,
It may be a monotonically decreasing linear function or the like.

In the second filter circuit 26,
The filters 27, 28 and 29 are analog filters 27A,
Analog filter circuit 26A to which 28A and 29A are applied
With this configuration, for example, it is possible to easily realize a filter having a time constant formed so as to be inversely proportional to the detection efficiency. On the other hand, the filters 27, 28 and 29 are replaced by the digital filter 2
By configuring the digital filter circuit 26B to which 7B, 28B, and 29B are applied, for example, it is possible to easily realize a filter having a time constant formed so as to be in inverse proportion to the detection efficiency and also to easily change the filter.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS.

A radiation measuring apparatus 1 showing this embodiment in FIG.
FIG. 2 shows a schematic diagram of the configuration of 0B. The radiation measuring apparatus 10B is provided with a third filter circuit 31, a filter circuit selecting means 32, and a radiation intensity monitoring means 33 in the output stabilizing means 14B. This radiation measuring apparatus 10B is provided with the output stabilizing means 1
4B includes a third filter circuit 31, a filter circuit selecting unit 32, and a radiation intensity monitoring unit 33, which is the same as the radiation measuring apparatus 10 shown in FIG. The same reference numerals are given to the parts and the description thereof will be omitted.

The radiation measuring apparatus 10B shown in FIG.
When calculating the dose equivalent of the incident radiation, the dose equivalent of the radiation is calculated in the same manner as the radiation measuring apparatus 10 shown in FIG. The radiation measuring apparatus 10B has an output stabilizing unit 14 that stabilizes the output even with respect to changes over time in energy and intensity of radiation (hereinafter referred to as changes in radiation field).
Equipped with B.

The third filter circuit 31 provided in the output stabilizing means 14B includes a plurality of, for example, two first filter circuits 21A and 21B having different time constants. Filter 2 of the first filter circuit filter 21B
The time constants of 2B, 23B, and 24B are each set to k (hereinafter, k is a time constant multiplication factor) times the time constant of the filters 22A, 23A, and 24A of the first filter circuit filter 21A. That is, the time constants of these filters are calculated by the filters 22A, 23A, and 24A as τa, τa ′,
τa ”, filters 22B, 23B, 24B are τb, τ
If b ′, τb ″ (where a ≠ b), the filter 2
The time constant τb = kτa of 2B and the time constant τb ′ = kτa ′ of the filter 23B. Note that k is a positive constant larger than 0 (except 1).

FIG. 9 shows the first filter circuits 21A and 21B.
22A, 23A, 24A and 22 provided in
The relationship between the filter outputs of B, 23B, and 24B and the time constant is shown.

The first filter circuit 21 illustrated in FIG.
Regarding the relationship between the filter outputs of A and 21B and the time constant, the time constants of the filters 22B, 23B and 24B are
It is set to be larger than the time constants of A, 23A, and 24A. That is, the time constant magnification k is set to k> 1.

The filter circuit selecting means 32 has a first filter circuit 21A having an appropriate time constant in accordance with a change in radiation intensity from the two first filter circuits 21A and 21B.
Alternatively, the first filter circuit 21B is selected. The filter selecting means 32 selects the filter circuit 21A having a filter having a short time constant when the change of the radiation field is large, and the filter 1 having the optimum time constant for the radiation energy incident from the filter circuit 21A. Select the pieces.

On the other hand, when the change in the radiation field is small, the filter circuit 21B having a filter with a long time constant is selected, and one filter having the optimum time constant for the radiation energy incident from the filter circuit 21B is selected. select.

The radiation intensity monitoring means 33 monitors changes in the radiation intensity, and determines the information for the filter circuit selecting means 32 to select a filter, that is, the magnitude of the change in the radiation intensity.

Monitoring of changes in the radiation intensity of the radiation intensity monitoring means 33 will be described with reference to FIG. FIG. 10 is an explanatory diagram showing the relationship between the radiation intensity and the incident radiation count rate. The radiation intensity monitoring means 33 previously obtains the relationship between the count rate of incident radiation and the radiation intensity,
The change in the radiation intensity is calculated from the obtained change in the count rate.

According to the third embodiment, the radiation measuring apparatus 1
As the output stabilizing means 14B for stabilizing the output of 0B,
For example, the first filter circuit 21 having a filter formed so that the filter output is inversely proportional to the detection efficiency is set to different time constant magnifications, and a third filter circuit 31 including a plurality of parallel-connected filters is provided; By providing a filter circuit selecting means 32 for selecting a filter circuit having an appropriate time constant with respect to a change in intensity and a radiation intensity monitoring means 33 for monitoring the magnitude of a change in radiation intensity, the radiation dose is calculated when the dose equivalent is calculated. An output that follows input well even when the field changes is realized, and stable output can be obtained without impairing the response speed.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 shows a schematic configuration diagram of a radiation measuring apparatus 10C showing the present embodiment. The radiation measuring apparatus 10C is provided with a third filter circuit 31, a radiation intensity monitoring means 33, and a filter circuit weighting calculation means 35 in the output stabilizing means 14C.

The radiation measuring apparatus 10C is the same as the radiation measuring apparatus shown in FIG. 1, except that the output stabilizing means 14C includes a third filter circuit 31, a radiation intensity monitoring means 33, and a filter circuit weighting calculating means 35. It is no different from the device 10. The output stabilizing means 14C is the output stabilizing means 14B included in the radiation measuring apparatus 10B shown in FIG.
On the other hand, there is no difference except that the filter circuit selection means 32 is provided and the filter circuit weighting operation means 35 is provided. Therefore, the same components as those of the radiation measuring apparatus 10 and the radiation measuring apparatus 10B are designated by the same reference numerals and the description thereof will be omitted.

Radiation measuring apparatus 10C shown in FIG.
Includes the output stabilizing unit 14C that stabilizes the output even when the radiation field changes, as in the radiation measuring apparatus 10B according to the third exemplary embodiment.

The output stabilizing means 14C inputs the output from the incident energy calculating means 13 into the filter circuit weighting calculating means 35 through the third filter circuit 31, and after the weighting calculation, outputs it to the integrator 15 as the integrating means. .

The filter circuit weight calculation means 35 receives inputs from both of the two first filter circuits 21A and 21B included in the third filter circuit 31. The filter circuit weighting calculation is performed by varying the addition ratio of the output of the first filter circuit 21A and the output of the first filter circuit 21B and adding them. Further, the addition ratio for the two first filter circuits 21A and 21B is set to 100% in total, and the input value and the output value of the third filter circuit 31 are formed to be the same.

The addition ratio of the two first filter circuits 21A and 21B is changed according to the magnitude of change in the radiation intensity monitored by the radiation intensity monitoring means 33. More specifically, the addition ratio of the filter circuit 21A having a filter with a short time constant to the two first filter circuits 21A and 21B included in the third filter circuit 31 when the change in the radiation field is large. Is increased to, for example, 90%, and the addition ratio of the other filter circuit 21B is decreased to, for example, 10%. On the other hand, when the change in the radiation field is small, the addition ratio of the filter circuit 21B having a filter with a long time constant is increased to, for example, 90%, and the other filter circuit 21
The addition ratio of A is reduced to, for example, 10%.

Radiation measuring apparatus 10C shown in FIG.
By changing the addition ratio of the filter circuits 21A and 21B provided in the third filter circuit 31 by the filter circuit weighting calculation means 35 of the output stabilizing means 14C,
When calculating the dose equivalent, a stable output can be obtained without impairing the response speed by realizing an output that follows the input even when the radiation field changes.

According to the fourth embodiment, the radiation measuring apparatus 1
As the output stabilizing means 14C for stabilizing the output of 0C,
The first filter circuit 21 having a filter formed so that the filter output is inversely proportional to the detection efficiency is set to different time constant magnifications, and a third filter circuit 31 including a plurality of filters connected in parallel is provided. By providing the radiation intensity monitoring means 33 for monitoring the magnitude of the change and the filter circuit weighting calculation means 35 for weighting the plurality of first filter circuits with respect to the change in the radiation field, when calculating the dose equivalent, An output that follows input well even when the radiation field changes is realized, and stable output can be obtained without impairing the response speed.

[0068]

As described above, the radiation measuring apparatus according to the present invention is provided with the output stabilizing means, and the output stabilizing means has the time constant corresponding to the detection efficiency of the incident radiation and the output is By providing the first filter circuit having a constant value filter, a stable output can be obtained without compromising the miniaturization request and response speed of the radiation detector when calculating the radiation dose equivalent.

Further, as the output stabilizing means, by providing a second filter circuit having a filter whose filter output is represented by a function of the elapsed time from the incidence of the radiation, it is possible to perform various dose equivalent calculation. And a stable output can be obtained without sacrificing the miniaturization requirement and response speed of the radiation detector. On the other hand, by configuring the second filter circuit to have at least one of an analog filter and a digital filter, it becomes easy to realize various responses of the filter output and change the filter.

Further, as the output stabilizing means, a third filter circuit having a plurality of first filter circuits,
By providing the filter circuit selection means and the radiation intensity monitoring means, it is possible to realize an output that follows the input even when the radiation field changes when calculating the dose equivalent, and to reduce the size of the radiation detector. And a stable output can be obtained without sacrificing the response speed. The same effect can be obtained by using a filter circuit weighting calculation means instead of the filter selection circuit.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a radiation measuring apparatus showing a first embodiment of the present invention.

FIG. 2A is an explanatory view showing a relationship between incident energy of radiation and detection efficiency, and FIG. 2B is an explanatory view showing a relationship between incident energy of radiation and a weighting coefficient.

FIG. 3A is a filter applied with incident energy E1 of radiation, and FIG. 3B is incident energy E2 of radiation.
FIG. 3C is an explanatory diagram showing the relationship between the elapsed time from the incidence of radiation and the filter output in the case of the filter applied with the incident energy E3 of the incident radiation in the case of the filter applied in FIG.

FIG. 4 is a schematic configuration diagram of a radiation measuring apparatus showing a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the relationship between filter output and elapsed time in the filter of the second filter circuit provided in the radiation measuring apparatus showing the second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a second filter circuit to which an analog filter is applied.

FIG. 7 is a schematic configuration diagram of a second filter circuit to which a digital filter is applied.

FIG. 8 is a schematic configuration diagram of a radiation measuring apparatus showing a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the relationship between the filter output of the filter circuits connected in parallel and the elapsed time in the third filter circuit included in the radiation measuring apparatus according to the third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing the relationship between radiation intensity and count rate.

FIG. 11 is a schematic configuration diagram of a radiation measuring apparatus showing a fourth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a conventional radiation measuring apparatus.

[Explanation of symbols]

10 Radiation Measuring Device 11 Radiation Detector (Radiation Detection Means) 12 Detected Energy Calculating Means 13 Incident Energy Calculating Means 14 Output Stabilizing Means 15 Integrators (Integrating Means) 17 Preamplifier 18 Wave Height Analyzer 19 Weighting Calculator 21 First Filter Circuit 22 Time constant τ1 applied to incident energy E1
Filter 23 with constant output having time constant τ2 applied to incident energy E2
Constant output filter 24 with time constant τ3 applied to incident energy E3
A filter 26 having a constant output and a second filter circuit 27. A filter 28 that changes with the lapse of time since the output applied to the incident energy E1 is incident. The output applied to the incident energy E2 is incident. The filter 29 that changes with the elapsed time from the filter 31 that changes with the elapsed time after the output applied to the incident energy E3 changes 31 the third filter circuit 32 the filter circuit selecting unit 33 the radiation intensity monitoring unit 35 the filter circuit Weighting calculation means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuyuki Maekawa             2-1, Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa             Ceremony Company Toshiba Hamakawasaki Factory (72) Inventor Hirotaka Sakai             No. 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation             Fuchu Office (72) Inventor Teruji Mizuteru             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office F term (reference) 2G088 KK01 KK24 LL05 LL15

Claims (7)

[Claims] 1. A radiation detection means for detecting radiation, a detection energy calculation means for calculating the energy of the detected radiation, and a weighted calculation for the calculation result of the energy of the detected radiation to calculate the energy of the incident radiation. In a radiation measuring apparatus comprising an incident energy calculating means for calculating and an integrating means for integrating incident energy for a predetermined time,
A radiation measuring apparatus comprising an output stabilizing means for stabilizing the output of the radiation measuring apparatus. 2. The output stabilizing means has a first filter circuit which has a time constant according to the detection efficiency of incident radiation and which outputs a constant filter output. Radiation measuring device. 3. The output stabilizing means has a time constant according to the detection efficiency of incident radiation, and outputs the filter output as a function of the elapsed time from the incidence of radiation.
The radiation measuring apparatus according to claim 1, further comprising: 4. The output stabilizing means has a time constant according to the detection efficiency of incident radiation, and outputs the filter output as a function of the elapsed time from the incidence of radiation.
2. The radiation measuring apparatus according to claim 1, further comprising: a filter circuit, wherein the second filter circuit is formed by at least one of an analog filter circuit and a digital filter circuit. 5. The output stabilizing means changes a radiation intensity with a third filter circuit formed by connecting a plurality of the first filter circuits configured by filters having different time constants in parallel. The radiation measuring apparatus according to claim 1, further comprising radiation intensity monitoring means for monitoring and filter circuit selecting means for selecting an appropriate first filter circuit according to a change in radiation intensity. 6. A third filter circuit formed by connecting a plurality of the first filter circuits, which are filters having different time constants, in parallel with each other, and the output stabilizing means controls a change in radiation intensity. The radiation measuring apparatus according to claim 1, further comprising: a radiation intensity monitoring unit for monitoring; and a filter circuit weighting calculation unit for weighting and outputting the output of the third filter circuit according to a change in the radiation field. . 7. The radiation intensity monitoring means monitors a change in the count rate from the relationship between the incident radiation intensity and the count rate,
6. A change in radiation intensity is calculated.
Alternatively, the radiation measuring device according to item 6.