JP4394966B2 - Radiation detector - Google Patents

Description

  The present invention relates to a radiation detector.

Patent Document 1 below discloses a hand-held medical radiation detector that detects a source of gamma rays.
Japanese Patent Laid-Open No. 2-198385

  In the measurement of radioisotope concentration using a hand-held radiation detector, the concentration is usually simply determined according to the magnitude of the measured value obtained by the detector. However, it is often difficult to specify the location where the radioactivity is concentrated in the region where the radioactivity is distributed only from the magnitude of the measured value.

  Then, this invention makes it a subject to provide the radiation detector which can pinpoint the location where the radioactivity concentrates easily.

The radiation detector of the present invention is a detector that detects radiation and generates a detection signal; a data acquisition unit that receives the detection signal and acquires basic data equivalent to a radiation count value per predetermined unit time; A measurement start instruction unit for inputting a start signal for instructing the start of storage of the maximum value of the basic data, a storage unit for storing the maximum value of the basic data in response to the start signal, and a threshold value for the basic data A threshold value input unit for inputting information, a data processing unit that compares basic data with a threshold value and generates a predetermined notification control signal when the basic data exceeds the threshold value, and a predetermined notification in response to the notification control signal And a threshold value calculation unit that calculates a threshold value using the maximum value stored in the storage unit, and the threshold value calculation unit sets the threshold value Ct to the following formula Ct = n × Cm (where, Cm is the maximum value , The coefficient n is 0 <calculated according satisfy n ≦ 1), and is configured so that the information that specifies the coefficients n are input using the threshold input portion.
The radiation detector of the present invention includes a detection unit that detects radiation and generates a detection signal, and a data acquisition unit that receives the detection signal and acquires basic data equivalent to a radiation count value per predetermined unit time And a measurement start instruction unit for inputting a start signal for instructing the start of storage of the maximum value of the basic data, a storage unit for storing the maximum value of the basic data in response to the start signal, and a threshold for the basic data A threshold value input unit for inputting information to be designated, a data processing unit that compares basic data with a threshold value and generates a predetermined notification control signal when the basic data exceeds the threshold value, and a predetermined value in response to the notification control signal And a measurement stop instruction unit for inputting a stop signal for instructing to stop storing the maximum value, and the storage unit stops storing the maximum value in response to the stop signal. Both Includes a single switch as measurement start instructing unit and the measurement stop instruction section is configured to start signal or a stop signal in response to the operation of the switch is input.

  In the radiation detector of the present invention, the user can specify a threshold value for determining whether or not to cause the notification unit to execute notification. The region where the notification is executed under a higher threshold value has a higher radioactivity concentration. When the measurement region is repeatedly scanned using the radiation detector of the present invention while gradually increasing the threshold value, the region where the notification is executed gradually narrows. Therefore, even when measuring a radioactivity distribution with a low contrast (concentration gradient), it is possible to easily identify a location where radioactivity is concentrated by repeating scanning while appropriately increasing the threshold value.

The radiation detector may further include a threshold value calculation unit that calculates the threshold value using the maximum value stored in the storage unit. The threshold value calculation unit sets the above threshold value Ct to the following formula Ct = n × Cm
(Here, Cm is the maximum value of the basic data, and the coefficient n satisfies 0 <n ≦ 1). Information specifying the coefficient n may be input using a threshold value input unit.

  The radiation detector may further include a measurement stop instructing unit for inputting a stop signal instructing to stop storing the maximum value. The storage unit may stop storing the maximum value in response to the stop signal.

  The radiation detector may include a single switch as a measurement start instruction unit and a measurement stop instruction unit. A start signal or a stop signal may be input according to the operation of the switch.

  The detection unit may generate a pulse signal as the detection signal. The data acquisition unit may count the pulse signal and acquire a value reflecting the count value of the pulse signal per unit time as basic data.

  The detection unit may generate a charge as a detection signal. The data acquisition unit may acquire a value reflecting the total charge received from the detection unit over a unit time as basic data.

  According to the radiation detector of the present invention, even when measuring a radioactivity distribution with a low contrast, it is possible to easily identify a location where radioactivity is concentrated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  The present embodiment relates to a hand-held cordless radiation detector 100. FIG. 1 is a plan view showing the radiation detector 100. As shown in FIG. 1, the radiation detector 100 includes an elongated housing 1 and a radiation detector 2 extending from the tip of the housing 1.

  The housing 1 is a hollow body having a substantially symmetric shape around its central axis. The housing 1 has a handle 10 that is gripped by a user of the radiation detector 100 and a body 12 that is connected to the tip of the handle 10. The body 12 is provided with a display device 14 for displaying various information related to radiation detection, and an operation unit 15 operated by a user to use the radiation detector 100.

  The radiation detection unit 2 includes an elongated cylindrical support member 20 protruding from the front end of the housing 1 and a radiation detection probe unit 22 attached to the front end of the support member 20. The base end of the support member 20 is connected to the center of the distal end portion of the housing 1. The probe unit 22 includes a radiation detection element (not shown) and a collimator (not shown). When the radiation detection element receives incoming radiation photons, the radiation detection element generates an electrical detection signal in accordance with the physical information of the radiation photons. Examples of the detection signal include a pulse signal having a peak value corresponding to the energy of radiation photons, and a charge (current) corresponding to the number and energy of radiation photons. Further, the radiation detection element may be a semiconductor element or a combination of a scintillator that emits light upon incidence of radiation and a photoelectric converter that detects the light emission. The collimator blocks radiation coming from the unwanted orientation toward the radiation detection element, thereby increasing the directivity of the radiation detector.

  FIG. 2 is a functional block diagram of the radiation detector 100. As shown in FIG. 2, the radiation detector 100 includes a control unit 30 and an output unit 32 in addition to the radiation detection unit 2. The control unit 30 and the output unit 32 and their drive power supply (not shown) are included in the body 12 and the handle 10 of the radiation detector 100.

  The control unit 30 includes a data acquisition unit 34, a maximum value storage unit 36, a threshold value calculation unit 38, a data processing unit 40, and the operation unit 15.

  The data acquisition unit 34 is a signal processing circuit that is electrically connected to the radiation detection element incorporated in the probe unit 22. Hereinafter, in the present embodiment, a case where the detection signal is a pulse signal will be described. The data acquisition unit 34 includes a preamplifier that receives and amplifies a pulse signal as a detection signal from the radiation detection element, and a main amplifier that further amplifies the pulse signal. The data acquisition unit 34 further includes a pulse height discriminator for selecting an amplified pulse signal having a desired peak value or more from a pulse signal amplified by the main amplifier (hereinafter referred to as “amplified pulse signal”). The wave height discriminator compares the wave height value of the amplified pulse signal with a predetermined count identification threshold value. This count identification threshold is used to select an amplified pulse signal having a desired peak value or higher from the amplified pulse signal. The wave height discriminator generates an output pulse signal by selecting a component equal to or higher than the count discrimination threshold from the amplified pulse signal. The data acquisition unit 34 further includes a scaler that counts the output pulse signal of the wave height discriminator. The detection signals generated by the radiation detection unit 2 are counted in this way. The data acquisition unit 34 repeatedly generates output signals corresponding to the count value of the detection signal per predetermined unit time at predetermined time intervals, and outputs the output signals to the output unit 32, the maximum value storage unit 36, and the data processing unit. Send to 40. This output signal level is equivalent to a radiation count value per predetermined unit time. The radiation count value reflects the intensity of the radiation incident on the detection unit. Hereinafter, data equivalent to the radiation count value per unit time is referred to as “basic data”.

  The maximum value storage unit 36 continuously receives basic data from the data acquisition unit 34 and stores the maximum value in the basic data. This maximum value is sent to the threshold value calculation unit 38.

  The threshold value calculation unit 38 calculates a detection sound threshold value using the maximum value of the basic data. This detection sound threshold value is used to determine whether or not to sound the detection sound, and corresponds to the threshold value in the claims. Formulas used for calculating the detection sound threshold will be described later. The threshold calculator 38 sends the calculated detection sound threshold to the data processor 40.

  The data processing unit 40 is electrically connected to the data acquisition unit 34 and receives basic data from the data acquisition unit 34. The data processing unit 40 compares the detection sound threshold value sent from the threshold value calculation unit 38 with the basic data, and determines whether or not to sound the detection sound. When the data processing unit 40 determines to sound the detection sound, the data processing unit 40 sends a notification control signal to the sound output device 42 in the output unit 32 to cause the sound output device 42 to sound the detection sound. On the other hand, when it is determined not to sound the detection sound, the notification control signal is not sent to the audio output device 42.

  The operation unit 15 includes a maximum value measurement instruction unit 16 that is operated to input a signal for starting and stopping measurement of the maximum value of the basic data, and a threshold that is operated to input information for specifying a detection sound threshold. And an input unit 18. The maximum value measurement instruction unit 16 includes a measurement start button 16a for inputting a start signal for instructing start of measurement of the maximum value, and a measurement stop button 16b for inputting a stop signal for instructing stop of the measurement. It is out. The threshold value input unit 18 is a coefficient increase button 18a for inputting a signal for increasing a coefficient (described later) used for calculation of the detected sound threshold value, a coefficient decrease button 18b for inputting a signal for decreasing the coefficient, And a threshold setting button 18c for inputting a signal for instructing start and end of designation of the detection sound threshold.

  The output unit 32 includes the display device 14 and an audio output device 42. The display device 14 sequentially receives basic data from the data acquisition unit 34 and displays a count value per unit time indicated by the basic data. The sound output device 42 is a device for notifying that the count value per unit time exceeds the detection sound threshold, and sounds the detection sound in response to the notification control signal from the data processing unit 40.

  Hereinafter, a method for identifying a location having a high radioactivity concentration using the radiation detector 100 will be described with reference to FIGS. 3 and 4. FIG. 3 is an explanatory diagram schematically showing this method, and FIG. 4 is a flowchart of this method.

  FIG. 3A shows a measurement region 50 in which the radioactivity is distributed. The user specifies the location where the radioactivity is concentrated in the measurement area 50 by the following procedure. First, the maximum count value per unit time of radiation flying from the region 50 is measured. For this purpose, the user inputs a start signal by pressing the detection start button 16a of the radiation detector 100 (step S402). Thereby, the radiation detector 100 is set to the maximum value measurement mode. As described above, the maximum value storage unit 36 is set to store the maximum value of the basic data, that is, the maximum count value per unit time, in response to the depression of the detection start button 16a.

  Next, as shown in FIG. 3B, the user moves the radiation detection probe unit 22 within the measurement area 50 and scans the entire measurement area 50 (step S404). In response to this, the data acquisition unit 34 measures radiation over the entire region to be measured 50 and sequentially sends basic data equivalent to the count value per unit time to the maximum value storage unit 36.

  The maximum value storage unit 36 stores the maximum value of basic data (step S406). The maximum value storage unit 36 includes a comparison circuit, and compares the basic data received from the data acquisition unit 34 with the basic data already stored. When the received basic data is larger than the stored basic data, the maximum value storage unit 36 updates the stored content to the received basic data. As a result, the maximum value of the basic data is held in the maximum value storage unit 36.

  When the entire scan of the measured region 50 is completed, the user presses the measurement stop button 16b and inputs a stop signal (step S408). In response to this, the maximum value measurement mode of the radiation detector 100 is canceled. The maximum value storage unit 36 is set so as not to update the stored content, and stops storing the maximum value of the basic data. In addition, the maximum value stored in the maximum value storage unit 36 is sent to the display device 14. The display device 14 displays the maximum value as the maximum count value per unit time (step S410).

  Next, the user presses the threshold setting button 18c (step S412). Thereby, the user can set a detection sound threshold value for determining whether or not to sound the detection sound. The user operates the coefficient increase button 18a and the coefficient decrease button 18b to input information specifying the coefficient n (0 <n ≦ 1), thereby specifying the detection sound threshold (step S414). Each time the coefficient increase button 18a and the coefficient decrease button 18b are pressed once, the coefficient n increases or decreases by a predetermined step value.

  When the coefficient n is determined, the user presses the threshold setting button 18c again, and the setting of the detection sound threshold is completed (step S416). The threshold calculation unit 38 calculates the detected sound threshold according to the following formula.

Ct = n × Cm (1)
Here, Ct is a detection sound threshold value, Cm is the maximum value of the basic data stored in the maximum value storage unit 36, and n is the coefficient specified by the user.

  The threshold value calculation unit 38 reads the maximum value Cm from the maximum value storage unit 36 in response to the second pressing of the threshold value setting button 18c, and uses the coefficient n designated using the coefficient increase button 18a and the coefficient decrease button 18b. Then, the above equation (1) is calculated. The calculated detection sound threshold Ct is sent to the data processing unit 40. According to the experience of the present inventor, the value of n used in the calculation of the first threshold is preferably 1/4.

Next, the user moves the radiation detection probe unit 22 in the measurement area 50 and scans the entire measurement area 50 again (step S418). In response to this, basic data is sent from the data acquisition unit 34 to the data processing unit 40. The data processing unit 40 compares this basic data with the detected sound threshold value calculated in step S416. When the basic data exceeds the detection sound threshold, the data processing unit 40 sends a notification control signal to the sound output device 42 to make the detection sound sound. On the other hand, when the basic data is equal to or lower than the detection sound threshold, the data processing unit 40 does not generate the notification control signal, and thus does not sound the detection sound. (Step S420). If the detection sound threshold is set appropriately, the region 51 where the detection sound is produced becomes narrower than the measurement region 50 as shown in FIG.

  Thereafter, the user repeats the processes after step S412. That is, the user presses the threshold setting button 18c (step S412), and re-specifies the detection sound threshold (step S414). At this time, the user presses the coefficient increase button 18a to increase the coefficient n so that the detected sound threshold becomes high. Thereafter, the user presses the threshold setting button 18c to determine the detection sound threshold (step S416). Subsequently, the radiation detection probe unit 22 is moved in the region 51 to scan the entire region 51 (step S418), and the region 52 where the detection sound is generated is specified (step S420). Since the detection sound threshold value has increased in step S414, the region 52 where the detection sound sounds is narrower than the region 51, as shown in FIG.

  By repeating such a procedure, the region where the detection sound is generated in the region to be measured 50 can be gradually reduced from region 51 to region 52 to region 53. The region where the detection sound is generated under a higher threshold has a higher radioactivity concentration. Therefore, by repeating the procedures of steps S412 to S418, it is possible to specify a location where radioactivity is concentrated.

  Below, the advantage of the radiation detector 100 is demonstrated. In the radiation detector 100, the user can specify a threshold value for determining whether or not to sound a detection sound. By repeating the scan in the measurement area while gradually increasing the threshold value and gradually narrowing the area where the detection sound is generated, it is possible to identify the location where the radioactivity is concentrated. The threshold value is calculated using the maximum value of the basic data equivalent to the maximum count value of radiation and the coefficient n. Therefore, it is not necessary to obtain a background count value for determining the threshold value. In actual radiation measurement sites, there are cases where the background count value is large due to various factors. In this case, the method of obtaining the background count value varies depending on the user. For this reason, if the threshold value is calculated using the background count value, an appropriate threshold value cannot be obtained, and the measurement accuracy may decrease. In the present embodiment that does not use the background count value, the measurement accuracy is not affected by the difference in the background acquisition method by the user. As a result, even when measuring a radioactivity distribution with a low contrast (concentration gradient), the location where radioactivity is concentrated can be easily and accurately specified by gradually increasing the threshold value.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

  In the above embodiment, the detection sound emitted from the audio output device 42 is notified that the basic data has exceeded the detection sound threshold. However, the notification unit is not limited to the audio output device, and may perform other types of notification indicating that the basic data exceeds the detection sound threshold. For example, the notification unit may be the display device 14. In this case, in response to the notification control signal from the data processing unit 40, the display device 14 may display predetermined notification information (for example, characters and graphics). The notification unit may be a vibration mechanism. In this case, the vibration mechanism may vibrate the radiation detector 100 in response to the notification control signal from the data processing unit 40. Furthermore, the radiation detector may execute a plurality of notifications when the basic data exceeds a detection sound threshold.

  In the above-described embodiment, when the entire area to be measured 50 is scanned for the second time and thereafter, the notification unit performs notification (that is, the sound output device 42 sounds a detection sound). However, the notification unit may perform notification according to the size of the basic data even when the measurement area 50 is scanned for the first time. In this case, the larger the basic data, the higher the output level of the notification unit (for example, the larger the detection sound), and the larger the basic data, the narrower the notification execution interval (for example, at regular time intervals). The time interval of the detection sound may be narrow).

  In the above embodiment, when the user operates the threshold value input unit 18 to specify the coefficient n, the detected sound threshold value is indirectly specified. However, the user may be able to directly specify the detection sound threshold value by operating the threshold value input unit. The coefficient n may be n = 1−m (the coefficient m satisfies 0 ≦ m <1), and the user may specify the coefficient m by operating the threshold value input unit 18.

  In the above-described embodiment, separate buttons 16a and 16b are provided for inputting a start signal and a stop signal instructing start and stop of measurement of the maximum value of the basic data. However, a single switch may be provided in the radiation detector for inputting the start signal and the stop signal. In this case, either a start signal or a stop signal is input according to the operation of the switch. For example, a start signal and a stop signal may be alternately input each time the switch is turned on and off, and the maximum value storage unit 36 may alternately start and stop storing the maximum value accordingly. Alternatively, either a start signal or a stop signal may be input according to the time for which the switch is pressed. For example, a signal for instructing measurement start may be input when the switch is pressed for a long time, and a signal for instructing measurement stop may be input for a short press of the switch, or vice versa. Further, only the switch for inputting the start signal may be provided in the radiation detector, and the maximum value of the basic data may be stored in the maximum value storage unit 36 for a predetermined time after the switch is turned on. In this case, it is necessary to finish scanning the entire measurement area before the predetermined time elapses.

  In the embodiment described above, two of the coefficient increase button 18a and the coefficient decrease button 18b are provided as coefficient instruction units for inputting information specifying the coefficient n. However, instead of these, a single input device such as a scale knob may be provided as the coefficient instruction section.

  In the above embodiment, the single button 18c is provided to instruct the start and end of the designation of the detection sound threshold. However, separate switches may be provided to instruct the start and end of the designation of the detection sound threshold.

  In the above embodiment, the detection signal from the radiation detection unit 2 is output as a pulse signal and counted. However, the detection signal from the radiation detection unit 2 is a charge, the data acquisition unit 34 accumulates the charge from the radiation detection unit 2 over a predetermined unit time, and a value reflecting the accumulated total charge amount is used as basic data. May be handled. In this case, the basic data is equivalent to the radiation count value per unit time.

It is a top view which shows the radiation detector of embodiment. It is a functional block diagram of the radiation detector shown by FIG. It is explanatory drawing which shows roughly the method of specifying the location with high radioactivity concentration. It is a flowchart which shows the procedure which pinpoints a location with high radioactivity concentration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Radiation detection part, 10 ... Handle, 12 ... Body part, 15 ... Operation part, 16 ... Maximum value measurement instruction | indication part, 16a ... Measurement start button, 16b ... Measurement stop button, 18 ... Threshold input part, 18a ... coefficient increase button, 18b ... coefficient decrease button, 18c ... threshold value setting button, 20 ... support member, 22 ... radiation detection probe unit, 30 ... control unit, 32 ... output unit, 34 ... data acquisition unit, 36 ... maximum value Storage unit, 38... Threshold value calculation unit, 40... Data processing unit, 42.

Claims (6)

A detector that detects radiation and generates a detection signal;
A data acquisition unit that receives the detection signal and acquires basic data equivalent to a radiation count value per unit time;
A measurement start instruction unit for inputting a start signal instructing the start of storage of the maximum value of the basic data;
A storage unit for storing the maximum value in response to the start signal;
A threshold value input unit for inputting information specifying a threshold value for the basic data;
A data processing unit that compares the basic data with the threshold and generates a predetermined notification control signal when the basic data exceeds the threshold;
A notification unit that performs predetermined notification in response to the notification control signal;
A threshold value calculation unit that calculates the threshold value using the maximum value stored in the storage unit;
Equipped with a,
The threshold value calculation unit calculates the threshold value Ct by the following formula:
Ct = n × Cm
(Here, Cm is the maximum value, and coefficient n satisfies 0 <n ≦ 1)
According to
Radiation detector information for specifying the coefficient n has are entered using the threshold input unit. A measurement stop instructing unit for inputting a stop signal instructing to stop storing the maximum value;
The storage unit stops storing the maximum value in response to the stop signal;
The radiation detector according to claim 1 . The radiation detector according to claim 2 , wherein a single switch is provided as the measurement start instruction unit and the measurement stop instruction unit, and the start signal or the stop signal is input according to an operation of the switch.   A detector that detects radiation and generates a detection signal;
  A data acquisition unit that receives the detection signal and acquires basic data equivalent to a radiation count value per unit time;
  A measurement start instruction unit for inputting a start signal instructing the start of storage of the maximum value of the basic data;
  A storage unit for storing the maximum value in response to the start signal;
  A threshold value input unit for inputting information specifying a threshold value for the basic data;
  A data processing unit that compares the basic data with the threshold and generates a predetermined notification control signal when the basic data exceeds the threshold;
  A notification unit that performs predetermined notification in response to the notification control signal;
  A measurement stop instructing unit for inputting a stop signal instructing to stop storing the maximum value;
With
  The storage unit stops storing the maximum value in response to the stop signal,
  A radiation detector comprising a single switch as the measurement start instructing unit and the measurement stop instructing unit, and receiving the start signal or the stop signal in accordance with the operation of the switch. The detection unit generates a pulse signal as the detection signal,
The data acquisition unit counts the pulse signal and acquires a value reflecting the count value of the pulse signal per unit time as the basic data.
The radiation detector in any one of Claims 1-4. The detection unit generates a charge as the detection signal,
The data acquisition unit acquires, as the basic data, a value reflecting the total charge received from the detection unit over the unit time;
The radiation detector in any one of Claims 1-4.

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